QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

HOME  |   SEARCH  |   ARCHIVE  |   SUBSCRIBE  |   CONTACT  |   HELP

This Article Abstract Full Text (PDF) Submit an eLetter Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (173) Citing Articles via Google Scholar Google Scholar Articles by Weldon, D. T. Articles by Mantyh, P. W. Search for Related Content PubMed PubMed Citation Articles by Weldon, D. T. Articles by Mantyh, P. W.

 Previous Article  |  Next Article 

The Journal of Neuroscience, March 15, 1998, 18(6):2161-2173

Fibrillar -Amyloid Induces Microglial Phagocytosis, Expression of Inducible Nitric Oxide Synthase, and Loss of a Select Population of Neurons in the Rat CNS In Vivo

Derik T. Weldon¹, Scott D. Rogers², Joseph R. Ghilardi², Matthew P. Finke², James P. Cleary^{3, 5}, Eugene O'Hare^{4, 5}, William P. Esler⁶, John E. Maggio⁶, and Patrick W. Mantyh²

¹ School of Medicine, Departments of ² Preventive Sciences, ³ Psychology, and ⁴ Pharmacology, University of Minnesota, Minneapolis, Minnesota 55455, ⁵ Geriatric Research Education and Clinical Center, Veterans Affairs Medical Center, Minneapolis, Minnesota 55417, and ⁶ Department of Pharmacology and Cell Biophysics, University of Cincinnati, Cincinnati, Ohio 45267

	ABSTRACT

Top Abstract Introduction Materials & Methods Results Discussion References

To determine the stability of -amyloid peptide (A) and the glial and neuronal changes induced by A in the CNS in vivo, we made single injections of fibrillar A (fA), soluble A (sA), or vehicle into the rat striatum. Injected fA is stable in vivo for at least 30 d after injection, whereas sA is primarily cleared within 1 d. After injection of fA, microglia phagocytize fA aggregates, whereas nearby astrocytes form a virtual wall between fA-containing microglia and the surrounding neuropil. Similar glial changes are not observed after sA injection. Microglia and astrocytes near the injected fA show a significant increase in inducible nitric oxide synthase (iNOS) expression compared with that seen with sA or vehicle injection. Injection of fA but not sA or vehicle induces a significant loss of parvalbumin- and neuronal nitric oxide synthase-immunoreactive neurons, whereas the number of calbindin-immunoreactive neurons remains unchanged. These data demonstrate that fA is remarkably stable in the CNS in vivo and suggest that fA neurotoxicity is mediated in large part by factors released from activated microglia and astrocytes, as opposed to direct interaction between A fibrils and neurons.

Key words: Alzheimer's disease; glia; microglia; astrocyte; neurotoxicity; nitric oxide synthase; inducible nitric oxide synthase

	INTRODUCTION

Top Abstract Introduction Materials & Methods Results Discussion References

Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive memory loss and dementia. The pathological hallmarks of AD are extracellular plaques containing -amyloid (A), dystrophic neurites, activated microglia, reactive astrocytes, and neuronal loss (Selkoe, 1991). Several lines of evidence suggest that A is directly involved in the neuropathology observed in AD. A deposition is an invariant feature of AD, and there is a strong correlation between amyloid burden at death and the degree of dementia in life (Selkoe, 1994; Cummings and Cotman, 1995). Most importantly, several genetically heritable forms of AD are tightly linked to mutations of the amyloid precursor protein gene on chromosome 21 (Goate et al., 1991), which cause an increase in A production (Citron et al., 1992). Heritable forms of AD linked to mutations on chromosomes 14 and 1 also seem to alter A processing (Scheuner et al., 1996; Selkoe, 1997).

A is a 39-43-amino-acid hydrophobic peptide encoded by the gene for the much larger amyloid precursor protein (Glenner and Wong, 1984; Kang et al., 1987). A is constitutively produced in cells, and soluble A (sA) is present at similar concentrations (10⁹ M) in normal and AD CSF, indicating that A is a natural rather than a pathogenic product (Haass et al., 1992; Seubert et al., 1992; Shoji et al., 1992; Busciglio et al., 1993; van Gool et al., 1995). Several studies have shown that sA will spontaneously form insoluble aggregates at high concentrations (10³ to 10⁵ M) and that the presence of other factors, such as metals, proteoglycans, or apoliopoprotein E4, can influence A aggregation (Fraser et al., 1992; Mantyh et al., 1993; Bush et al., 1994; Ma et al., 1994; Sanan et al., 1994; Wisniewski et al., 1994; Evans et al., 1995; Esler et al., 1996).

Conversion of sA to insoluble, fibrillar A (fA), an A conformation similar to that found in the AD brain, has been reported to increase greatly A toxicity in neuronal cultures (Pike et al., 1991a,b, 1993, 1995; Mattson et al., 1992). However, other studies have reported that sA at concentrations near that found in human CNS (10⁹ M) has marked neurotoxic and/or neuroprotective effects on neurons in vitro (Koh et al., 1990; Yankner et al., 1990; Harrigan et al., 1995; Kelly et al., 1996). Although much of the above data suggest that A is neurotoxic in vitro, substantial uncertainty remains as to the form of A that is neurotoxic in vivo, the long-term stability of A, and the mechanism(s) via which A may induce neurotoxicity in vivo.

In the present study, we use microglia, astrocyte, and neuronal markers to study the glial and neuronal changes induced by soluble and fibrillar forms of A in the CNS in vivo. The use of microglia and astrocyte markers allows us to address the question of direct versus indirect toxicity of A and to determine whether microglia and astrocytes are differentially involved in the CNS response to A. We chose the striatum as the CNS area in which to examine the effects of A, because this forebrain area is affected in AD (Selden et al., 1994), is a relatively homogeneous brain area that allows quantification of A-induced cellular changes, and has well defined neuronal subpopulations that are readily quantifiable using immunohistochemical methods (Kawaguchi et al., 1995). In the present study, we have also used confocal microscopy, because this imaging technique allows us to visualize simultaneously several fluorescent markers while providing unequivocal single-cell and intracellular resolution of the changes that A induces in the CNS.

	MATERIALS AND METHODS

Top Abstract Introduction Materials & Methods Results Discussion References

Preparation and characterization of fibrillar and soluble A. A1-40, synthesized by fluorenylmethoxycarbonyl chemistry and purified to near homogeneity (>98%), was obtained (Quality Control Biochemicals, Hopkinton, MA) and stored lyophilized at 20°C. Peptides used to produce fA and sA were characterized by reverse phase (RP)-HPLC, laser desorption mass spectroscopy (LD-MS), amino acid analysis (Benson et al., 1981), and size exclusion fast-protein liquid chromatography (SE-FPLC) (Soreghan et al., 1994).

Fibrillar A was prepared from solutions of 10⁴ M A in filtered PBS (10.0 mM NaH₂PO₄/Na₂HPO₄ and 100.0 mM NaCl, pH 7.5). Peptide solutions were initially clear, with no evidence of flocculation or incomplete dissolution; visible precipitate appeared only after extended agitation. The fresh A solution was allowed to incubate under vigorous agitation (Teflon-coated stir bar at 800 rpm) (Jarrett and Lansbury, 1992; Jarrett et al., 1993, 1994; Evans et al., 1995) at 23°C for 26-36 hr. After this incubation, the A solution was distinctly turbid, and >80% of the peptide could be sedimented by centrifugation (15,000 × g; 10 min). The fA solution was aliquoted (100 µl per vial), frozen on dry ice, and stored at 20°C until use.

To better characterize the fA assembly reaction, we performed time course experiments in triplicate with mixtures of ¹²⁵I-A and unlabeled A in microcentrifuge tubes (Evans et al., 1995) under conditions similar to those described above. At each time point, a 15 µl aliquot was taken from each tube and centrifuged (15,000 × g; 10 min), and the amount of ¹²⁵I-A in each of two 3 µl aliquots of the resulting supernatants was quantified using a gamma counter. Fibrillar A assembly followed a distinctly nonlinear time course with a lag time, indicative of a nucleation-dependent aggregation process (Jarrett and Lansbury, 1993). Fibrillar A from the preparative procedure described above was characterized by thioflavin S, Congo red, and anti-A immunohistochemical staining and then was examined for size distribution using light-field or fluorescence microscopy and image analysis. Individual fA aggregates had a median diameter of 12.3 µm, which compares favorably with the diameter of plaque cores (5-30 µm) purified from human AD brain (Selkoe and Abraham, 1986). Like amyloid plaques found in the AD brain, fA prepared in this manner displays typical Congo red birefringence under polarized light and is thioflavin S-positive, establishing that A prepared in this manner has a fibrillar morphology (Kirschner et al., 1986, 1987; Evans et al., 1995). Additionally, fA prepared in this manner serves as a template for A deposition in vitro in a manner similar to A deposition onto authentic AD tissue amyloid (Esler et al., 1997). Preparations of A not deliberately aggregated (sA) did not display Congo red birefringence or thioflavin S staining.

Fibrillar A prelabeled with thioflavin S was prepared from unlabeled fA described above. Aliquots were thawed, centrifuged (15,000 × g; 10 min), resuspended in 100 µl of thioflavin S solution (1% in distilled water; Sigma, St. Louis, MO), and allowed to incubate overnight on a shaking platform at 23°C. The solution was then centrifuged as described above, and the fA was resuspended and washed twice in 70% ethanol to remove excess dye. This thioflavin S-labeled fA was then prepared for injection by resuspending, after the second ethanol wash, in sterile artificial CSF (aCSF; 128.6 mM NaCl, 2.6 mM KCl, 2.0 mM MgCl₂, and 1.4 mM CaCl₂, pH 7.4) to a total A concentration of 10⁴ M. Unlabeled fA was prepared for injection by pelleting the unstained fA as described above and resuspending in sterile aCSF at an fA concentration of 10⁴ M. Soluble A solution was prepared by dissolving A (Quality Control Biochemicals) in sterile water to a concentration of 10⁴ M and was stored at 20°C in 100 µl aliquots until injection. No evidence of A aggregation was observed in the sA aliquots before or during the injection process.

Injection of A and preparation of brain tissue. Sprague Dawley rats (male; 200-250 gm; Harlan Sprague Dawley, Indianapolis, IN) were deeply anesthetized with sodium pentobarbital (60 mg/kg; Abbott Labs, Irving, TX) and then mounted in a small-animal stereotaxic instrument. The fA solution (10 µl) was injected stereotaxically into the striatum (anterior, 0.5 mm; lateral, 3.0 mm; and ventral, 6.5 mm) using a 26 gauge needle (Fig. 1A). Stereotaxic coordinates were measured from bregma (Paxinos and Watson, 1986). Injections of vehicle or 10⁴ M sA (10 µl) were made into the contralateral striatum. Each 10 µl injection of fA contained ~2400 individual aggregates.

View larger version (113K): [in this window] [in a new window]   Figure 1.   A, A confocal photomicrograph shows the location of fA injection into the rat striatum. The fA shown here (arrow) was prelabeled with thioflavin S before injection anterior 0.5 mm, lateral 3.0 mm, and ventral 6.5 mm relative to bregma (Paxinos and Watson, 1986). The image was constructed from six optical sections acquired at 1.0 µm intervals using a 4× lens. B-G, Fluorescent confocal images of injected fA in the striatum show that fA is stable in vivo. B-D, Injected fA is identified in tissue by labeling with anti-A. E-G, Injected fA prelabeled with thioflavin S is also readily observable in the striatum. Note that, although variability in the shape of the injection site is evident in the images, there is little decrease in the total amount of injected fA present over time. Also, no significant decrease in thioflavin S fluorescence is observed over time, suggesting injected fA monomers are not being replaced with endogenous rat A. Images were projected from six optical sections acquired at 1.0 µm intervals using a 10× lens. Scale bars: A, 1.0 mm; B-G, 75 µm.

Seventy-five animals were used in the present study. Injections of either unlabeled or thioflavin S-prelabeled fA were made into the striatum, with injections into the contralateral striatum of either sA or vehicle (aCSF or sterile water). The effects of fA, sA, and vehicle injections were analyzed 1, 7, 14, and 30 d after injection (n  3 for each treatment group). None of the animals used in the above experimental procedures showed signs of infection in the injection area before killing or after histological examination. Animals were group-housed with food and water available ad libitum in an American Association for Accreditation of Laboratory Animal Care-approved animal research facility. After the appropriate survival time, rats were killed by CO₂ asphyxiation and then rapidly perfused through the ascending aorta with 200 ml of PBS (3.0 mM Na₂HPO₄, 0.9 mM KH₂PO₄, and 154.0 mM NaCl, pH 7.4; 23°C) followed by 500 ml of PBS containing 4% formaldehyde (Sigma, 4°C). After perfusion, the brain was removed, blocked in the transverse plane, post-fixed in 4% formaldehyde (4°C; 1 d), and then placed in a 30% sucrose solution (4°C; 1 d). The brains were then serially sectioned at 20 µm using a cryostat microtome (Model OTF/AS; Bright Instrument Co.) and collected in PBS.

Immunohistochemical examination of A, glia, and neuronal markers. Immunohistochemical identification of A was performed by washing sections in Tris-buffered saline (TBS; 140 mM NaCl, 2.7 mM KCl, and 24.8 mM Tris base, pH 7.4) for 20 min and then in ethanol/distilled water (1:1) for 10 min. Sections were washed three times for 10 min each in TBS, washed in blocking solution containing TBS and 10% normal goat serum (NGS) for 30 min, and then incubated overnight at 23°C in TBS containing 1% NGS and polyclonal anti-A (R1282; 1:1500; a kind gift from Dr. D. Selkoe) raised against uncoupled synthetic A1-40 (Haass et al., 1992). Sections were washed three times for 10 min each in TBS and then incubated 1 hr at 23°C in TBS containing 1% NGS and biotinylated donkey anti-rabbit IgG (1:500; Jackson ImmunoResearch, West Grove, PA). Sections were washed three times for 10 min each in TBS and then incubated 45 min at 23°C in TBS containing 1% NGS and fluorescein (FITC)-conjugated avidin (1:200; Jackson ImmunoResearch). Sections were washed three times for 10 min each in TBS, then mounted by floating onto gelatin-coated slides, and coverslipped using PBS/glycerol (1:1).

Immunohistochemical identification of microglia was performed by washing sections in blocking solution containing PBS and 1% NGS for 30 min and then incubating overnight at 23°C in PBS containing 1% NGS and monoclonal anti-CD11b equivalent (OX-42; 1:10; Serotec, Indianapolis, IN). OX-42 is specific for the C3b_i complement protein receptor that is expressed in the CNS primarily, if not exclusively, by microglia. Sections were washed three times for 10 min each in PBS and then incubated 3 hr at 23°C in PBS containing 1% NGS and cyanine 3.18 (Cy3)-conjugated donkey anti-mouse IgG (1:600; Jackson ImmunoResearch). Sections were washed three times for 10 min each in PBS and then mounted and coverslipped as described above.

Immunohistochemical identification of astrocytes was performed by washing sections in blocking solution containing PBS, 1% NGS, and 0.3% Triton X-100 (Sigma) for 30 min and then incubating overnight at 23°C in PBS containing 1% NGS, 0.3% Triton X-100, and either monoclonal or polyclonal anti-glial fibrillary acidic protein (GFAP; 1:400; Sigma). Sections were washed three times for 10 min each in PBS and then incubated 3 hr at 23°C in PBS containing 1% NGS, 0.3% Triton X-100, and cyanine 5.18 (Cy5)-, Cy3-, or FITC-conjugated donkey anti-mouse or anti-rabbit IgG (Jackson ImmunoResearch) at concentrations of 1:600 (Cy3), 1:450 (Cy5), or 1:150 (FITC). Sections were washed three times for 10 min each in PBS and then mounted and coverslipped as described above.

Immunohistochemical identification of inducible nitric oxide synthase (iNOS) was performed by washing sections in blocking solution containing PBS and 10% bovine serum albumin (BSA; Sigma) for 1 hr and then incubating overnight at 4°C in PBS containing 10% BSA and polyclonal anti-iNOS (1:200; Biomol, Plymouth Meeting, PA), which is specific for the iNOS 130 kDa protein with no advertised cross-reactivity to endothelial nitric oxide synthase or neuronal nitric oxide synthase (nNOS). Cross-reactivity of the iNOS antibody was not tested in this study. Sections were washed three times for 10 min each in PBS and then incubated 3 hr at 23°C in PBS containing 10% BSA and Cy3-conjugated donkey anti-rabbit IgG (1:600; Jackson ImmunoResearch). Sections were washed three times for 10 min each in PBS and then mounted and coverslipped as described above.

Immunohistochemical examination of parvalbumin, nNOS, and calbindin neurons were performed by washing sections in blocking solution containing PBS, 1% NGS, and 0.3% Triton X-100 (Sigma) for 30 min and then incubating overnight at 23°C in PBS containing 1% NGS, 0.3% Triton X-100, and either monoclonal anti-parvalbumin (1:1000; Sigma), polyclonal anti-nNOS (1:500; Chemicon, Temecula, CA), or monoclonal anti-calbindin (1:300; Sigma). Sections were washed three times for 10 min each in PBS and then incubated 3 hr at 23°C in PBS containing 1% NGS, 0.3% Triton X-100, and Cy3-conjugated donkey anti-mouse or anti-rabbit IgG (1:600; Jackson ImmunoResearch). Sections were washed three times for 10 min each in PBS and then mounted and coverslipped as described above.

Image analysis. Size characterization of fA was done using a Leitz Orthoplan II microscope equipped for epifluorescence (Leitz, Wetzlar, Germany). Fibrillar A was labeled with thioflavin S as described above; then 10 µl of this solution was placed on a microscope slide, coverslipped, and visualized under fluorescence. The size distribution of 120 randomly selected fA aggregates was analyzed using the National Institutes of Health Image version 1.51 software program (National Institutes of Health, Bethesda, MD).

Immunofluorescence in brain tissue was examined using a MRC-1024 Confocal Imaging System equipped with a krypton/argon ion laser (Bio-Rad, Hercules, CA) in conjunction with an Olympus BX-75 microscope equipped for epifluorescence (Olympus Immunochemicals, Lake Success, NY). Labeled sections were imaged using filters appropriate for the specific visualization of fluorescein, cyanine 3.18, and cyanine 5.18 (Brelje et al., 1993; Kennedy et al., 1994). Images were acquired using two different methods. The first method involved collecting multiple scans of optical sections (z-series) that were acquired at 1.0 µm intervals. The second method involved collecting multiple scans of a single optical section using the Kalman imaging program, which allowed collection of low power confocal images while conserving the intensity and resolution of the original tissue staining. The optical sections were then projected into single images using image-processing software provided with the confocal system (Bio-Rad).

The total number of OX-42-immunoreactive microglia in fA, sA, or vehicle injection tracks was counted using confocal microscopy by optical sectioning (2.0 µm confocal z-series) in 200 × 300 µm grids (0.06 mm²). Astrogliosis and iNOS expression were quantified using confocal microscopy by measuring the total GFAP or iNOS immunofluorescence over a similarly defined area. Data units for total immunofluorescence calculations are in gray scale pixel values, ranging from 0 (dark) to 255 (saturation level). Because individual astrocytes grouped closely together in the injection were impossible to count accurately, it was necessary to quantify astrocytes (GFAP) and iNOS expression using total fluorescence.

To determine whether microglia or astrocytes in the injection site contained phagocytized fA or sA, we imaged A and OX-42 immunofluorescence from the same tissue section simultaneously. The four experimental time points were compared by averaging the percentage of total glia in the measured area (defined above) that contained phagocytized A. Twenty-four animals were used for this analysis (n = 3 animals per treatment group at each time point; seven sections analyzed per animal). The average number of microglia in each confocal gridded section at 1, 7, 14, and 30 d after injection was 20, 57, 73, and 75 (fA) and 20, 61, 33, and 15 (sA). Images of iNOS immunofluorescence with OX-42 or GFAP immunofluorescence were created using pairs of confocal images (iNOS + OX-42 and iNOS + GFAP) from the same tissue section. The pairs of images were imported using the National Institutes of Health Image version 1.51 software program, and the area of colocalization was computed by finding the regions of maximum signal overlap between the two images. To determine the percentage of microglia or astrocytes that express iNOS in the fA injection area, we counted iNOS-immunoreactive microglia or astrocytes using the confocal imaging system (area defined above).

To quantify neurons in and surrounding the defined fA and sA injection areas, we imaged GFAP immunofluorescence (marking the astrogliosis surrounding the fA and sA needle tracks) and parvalbumin, nNOS, or calbindin immunofluorescence on the same tissue sections simultaneously. Using a gridded eyepiece on a Leitz Orthoplan II microscope, we counted neurons in bins of increasing distance on both sides of the needle track at 10× magnification. The bins measured 0-125, 126-250, and 251-375 µm outward (medial and lateral) from the margin of the GFAP-immunoreactive astrogliosis. Fifteen animals, with fA and sA injected contralaterally, were used for this analysis (total number of sections = 55; total neurons counted within defined area, 862 [nNOS], 823 [parvalbumin], and 1529 [calbindin]). The total area of quantification was the same for each section.

Statistical analysis. All data are expressed as mean ± SEM. One-way ANOVA was performed using the StatView statistical software program (Abacus Concepts, Calabasas, CA).

	RESULTS

Top Abstract Introduction Materials & Methods Results Discussion References

Stability of fibrillar and soluble A

In the normal (noninjected) striatum or after injection of vehicle alone, no A immunofluorescence, Congo red birefringence, or thioflavin S staining is observed at any time point. After injection of sA, A immunofluorescence is only faintly visible and, when present, is almost invariably observed inside microglia immediately around the needle track at 1, 7, 14, and 30 d. At 1 d after sA injection, 9% of microglia within 150 µm of the needle track contain anti-A-immunoreactive material. By 30 d after injection, the percentage of microglia in the same area containing A-immunoreactive material increases to 19% (Fig. 2), but no difference in total A immunofluorescence in the area surrounding the injection site is observed at any time point (data not shown). The A-immunoreactive material detectable in microglia after sA injection does not display Congo red birefringence or thioflavin S staining at any time point, suggesting that this A is present in a nonfibrillar form.

View larger version (25K): [in this window] [in a new window]   Figure 2.   A is phagocytized by microglia over time. Fluorescent confocal images of fA (circles) or sA (triangles) labeled with anti-A were merged with confocal images of OX-42-immunoreactive microglia from the same tissue sections, allowing intracellular resolution and quantification of A inside microglia. Microglia actively phagocytize fA over time, because 93% of microglia within 150 µm of the fA needle track contain material that is both A-immunoreactive and Congo red-birefringent at 30 d after injection. In contrast, a relatively small percentage of microglia (10-20%) within 150 µm of the sA needle track contain A immunoreactivity at the observed time points; this A-immunofluorescent material is neither Congo red-birefringent nor thioflavin S-positive (data not shown) and thus lacks the characteristics of fA.

After injection of fA or of fA prelabeled with thioflavin S into the striatum, intense A immunoreactivity or thioflavin S fluorescence, respectively, is present at 1, 7, and 14 d after injection. Although the shape of the individual fA injection sites varied slightly between animals, no significant decrease in the quantity of fA in the striatum is observed at these time points, as measured by A immunofluorescence or thioflavin S fluorescence. Also, no decrease in thioflavin S fluorescence is observed, suggesting that the injected human fA remains stable in vivo and is not exchanged for endogenous rat A monomers at these time points (Fig. 1B-G). The fA remains stable and detectable within the striatum up to at least 30 d after injection (Fig. 3) and displays typical Congo red birefringence under polarized light at all time points (data not shown). Although the overall quantity of fA does not appear to decrease significantly after injection, there is a clear increase in the percentage of total fA that is phagocytized and concentrated within microglia over time. At 1 d after injection, the majority of fA remains in the extracellular space (Fig. 3A), although a significant minority of microglia (38%) within 150 µm of the needle track already contain phagocytized fA at this time point (Fig. 2). With increasing time after injection, nearly all of the injected fA is phagocytized and concentrated within microglia (Fig. 3B,C). By 30 d after injection, 93% of microglia within 150 µm of the needle track contain phagocytized fA (Fig. 2).

View larger version (156K): [in this window] [in a new window]   Figure 3.   Fluorescent confocal images show that microglia actively phagocytize injected fA, whereas astrocytes wall-off fA-containing microglia from the surrounding neuropil. A-C, fA prelabeled with thioflavin S appears red, and microglia labeled with anti-CD11b (OX-42) appear yellow. A, At 1 d after injection, activated microglia, characterized by short, thickened processes and marked cytoplasmic swelling, are observed surrounding injected fA. Note that some of these microglia are associated with injected fA along the outer margins of the needle track. B, C, At 30 d after injection, fA is not cleared from the site of injection but rather is contained almost exclusively within microglia in the needle track. D-F, fA prelabeled with thioflavin S appears red, and astrocytes labeled with anti-GFAP appear yellow. D, At 1 d after injection, no significant astrogliosis is observed surrounding injected fA. E, F, In contrast, a marked astrogliosis, characterized by activated astrocytes with swollen processes and increased GFAP immunofluorescence, is observed at 30 d after injection. Astrocytes are shown walling-off fA-containing microglia from surrounding tissue. Images of fA and microglia or astrocytes were taken from the same double-labeled tissue sections. Images were projected from 12 optical sections acquired at 1.0 µm intervals using a 10× or 40× lens. Scale bars: A, B, D, E, 50 µm; C, F, 10 µm.

Glial responses to injections of fibrillar A, soluble A, or vehicle

In the normal striatum, both microglia and astrocytes display a characteristic resting morphology. Microglia detectable using OX-42 immunoreactivity are evenly distributed throughout the striatum and possess long, thin, highly ramified processes connected to a cell body that has little observable cytoplasm (Barron, 1995). Astrocytes in the normal striatum that are GFAP-immunoreactive are also relatively evenly distributed, possessing a morphology characterized by a distinctly stellate-shaped cell body with little observable cytoplasm and long, thin radially extending processes (Eddleston and Mucke, 1993).

At 1 d after injection of vehicle alone, a large percentage of microglia surrounding the needle track have an activated morphology, characterized by short, thickened processes and marked cytoplasmic swelling (Barron, 1995). A gradient of microglial activation is observed at this time point, because nearly all microglia within 100 µm of the needle track assume this activated morphology, whereas microglia that are >150 µm from the needle track display a resting morphology similar to that observed in the normal striatum. At 7 d after injection, nearly all microglia observed up to 300 µm from the needle track possess an activated morphology. At the 14 and 30 d time points, the area showing microglial activation is significantly decreased, so that by 30 d after injection, only a thin line of activated microglia marking the needle track remain in the vehicle-injected striatum (Fig. 4A). This change in microglial morphology is mirrored by a change in the total number of microglia surrounding the needle track, which peaks at 7 d after injection and is followed by a gradual decline at days 14 and 30 (Fig. 5A). No differences in microglial morphology or number are observed at any time point when comparing vehicle injections of aCSF and sterile water.

View larger version (161K): [in this window] [in a new window]   Figure 4.   Microglia and astrocyte responses 30 d after vehicle or sA injection are shown. A, B, No difference in OX-42 immunofluorescence is observed in the needle track after vehicle or sA injection. C, D, Similarly, no difference in GFAP immunofluorescence is observed in the needle track after vehicle or sA injection. Images are Kalman averages of a single optical section acquired using a 20× lens. Scale bar, 50 µm.

View larger version (20K): [in this window] [in a new window]   Figure 5.   Injected fA induces a larger and more-sustained gliosis compared with that seen with injected sA or vehicle alone. A, The number of OX-42-immunoreactive microglia, quantified in 0.06 mm2 grids centered on fA (open circles), sA (closed triangles), or vehicle (open squares) needle tracks, is similar at 1 and 7 d after injection but is significantly increased in the fA injection area relative to the sA and vehicle injection areas at 14 and 30 d after injection. Note that at 1 d after injection, the number of microglia in the fA, sA, or vehicle injection area does not differ significantly from the number of microglia present in a comparable area of normal striatum. B, Astrogliosis, measured by computing the total intensity of GFAP immunofluorescence in 0.06 mm2 grids centered on fA (open circles), sA (closed triangles), or vehicle (open squares) needle tracks, is similar at 1, 7, and 14 d after injection. At 30 d after injection, GFAP immunofluorescence is significantly increased in the fA injection area relative to the sA and vehicle injection areas. Images used for microglia counts and GFAP immunofluorescence measurements were Kalman averages of a single optical section acquired using a 10× lens (*fA vs sA or vehicle, both p < 0.05).

Injection of vehicle alone also induces changes in the morphology and GFAP immunofluorescence of astrocytes surrounding the needle track. Astrocytes undergo a swelling of processes and show an increase in GFAP immunofluorescence, indicative of activation (Eddleston and Mucke, 1993; O'Callaghan et al., 1995). Evidence of astrocyte activation is faintly observable at 1 d after injection and is clearly evident at days 7 and 14. At 30 d after injection, this astrocyte activation decreases so that only a thin line of activated astrocytes marking the needle track remain in the vehicle-injected striatum (Fig. 4C). This change in astrocyte morphology is mirrored by a change in GFAP immunofluorescence, which peaks at 14 d after injection and is followed by a marked decline at day 30 (Fig. 5B). No differences in astrocyte morphology or GFAP fluorescence are observed at any time point when comparing vehicle injections of aCSF and sterile water.

Striatal injection of sA induces microglial and astrocyte changes that are nearly indistinguishable from those observed after injection of vehicle alone. However, one significant difference between the injection of sA and vehicle is that although vehicle injection alone never induces any detectable accumulation of A, injection of sA results in accumulation of anti-A immunoreactivity in ~10-20% of microglia in the needle track at the time points examined (Fig. 2). Those microglia that contain A immunoreactivity invariably have an activated morphology and maintain this morphology up to at least 30 d after injection. Even with the presence of microglia containing A immunoreactivity after sA injection, only a thin line of activated microglia and astrocytes, similar in appearance to the vehicle-injected striatum, remain at 30 d after sA injection (Fig. 4B,D). Neither the number of microglia nor the GFAP immunofluorescence surrounding the needle track differs significantly at any time point when comparing sA with vehicle injection (Fig. 5A,B).

Injection of fA induces several changes in microglia and astrocytes that are significantly different from those observed after injection of either vehicle or sA. The earliest difference observed when comparing fA and sA injection sites is in the percentage of microglia that contain A immunoreactivity. At 1 d after injection of fA, 38% of microglia within 150 µm of the needle track contain phagocytized fA. The percentage of microglia containing fA continues to rise until day 30, at which point 93% of microglia in the same area contain detectable concentrations of A immunoreactivity (Figs. 2, 3). At all time points examined, microglia that contain fA invariably have an activated morphology. No significant increase in astrocyte activation is observed at 1 d after fA injection (Fig. 3D). However, at 30 d after injection, a marked astrogliosis, characterized by activated astrocytes with swollen processes and increased GFAP immunofluorescence, is observed in the fA injection area. A virtual wall of activated, GFAP-immunoreactive astrocytes is observed surrounding the fA-containing microglia at 30 d after injection (Fig. 3E,F). Although changes in the number of microglia and in the GFAP immunofluorescence induced by injection of fA may initially be masked by changes induced by the damage associated with needle placement alone, there are significantly greater numbers of microglia within 150 µm of the needle track after fA compared with sA or vehicle injection at days 14 and 30 (Fig. 5A). Similarly, there is a significantly greater concentration of GFAP immunofluorescence within 150 µm of the needle track after fA compared with sA or vehicle injection at day 30 (Fig. 5B).

Fibrillar A induces iNOS expression in microglia and astrocytes

In the normal striatum, <20% of the microglia and <5% of astrocytes display iNOS immunoreactivity, and those microglia and astrocytes that do express iNOS do so at low levels. Within 150 µm of the needle track, there is a significant increase in iNOS immunofluorescence above those levels observed in the normal striatum at 30 d after vehicle (64% increase) or sA (75% increase) injection, but this difference between vehicle and sA injection did not reach statistical significance (data not shown). Those microglia and astrocytes that express iNOS at 30 d after vehicle or sA injection seem to be from the same small population of microglia and astrocytes that remain activated and mark the thin line of the needle track. No increase in iNOS immunofluorescence above the level in the normal striatum is observed in tissue areas outside of the vehicle or sA needle tracks.

Compared with that in the normal striatum, iNOS immunofluorescence is 121% higher within 150 µm of the needle track at 30 d after fA injection. Injection of fA also promotes an increase in iNOS expression that significantly exceeds the iNOS expression observed after vehicle or sA injection (data not shown). Simultaneous imaging of iNOS and OX-42 or GFAP immunofluorescence on the same tissue sections confirms that fA induces iNOS expression in both microglia and astrocytes (Fig. 6). At 30 d after injection, nearly 100% of microglia that contain phagocytized fA are also iNOS-immunoreactive. Similarly, nearly 100% of astrocytes within 100 µm of microglia containing A are iNOS-immunoreactive. Outside of this area, iNOS expression closely resembles that of the normal striatum described above.

View larger version (123K): [in this window] [in a new window]   Figure 6.   iNOS expression by microglia and astrocytes is increased 30 d after fA injection. A, B, D, E, Tissue sections were labeled with anti-iNOS and with either OX-42 or anti-GFAP. C, F, Using the National Institutes of Health Image 1.51 software program, we merged iNOS and OX-42 or GFAP images, and the area of maximum signal overlap between the images was computed to show immunofluorescence colocalization. Note that microglia in the fA injection area, which were shown in Figure 3 to contain fA, also express iNOS at 30 d after injection, whereas most microglia outside the injection area do not. Also note that only those astrocytes forming a virtual wall around the injected area, within 100 µm of the A-containing microglia, express high levels of iNOS. The iNOS, OX-42, and GFAP images were taken from the same double-labeled tissue sections and are Kalman averages of a single optical section acquired using a 10× lens. Scale bar, 50 µm.

Fibrillar A-induced loss of specific neuronal populations

To determine the effects of fA and sA injections on striatal neurons, we labeled a population of projection neurons using anti-calbindin and two distinct populations of interneurons using anti-parvalbumin and anti-nNOS. Spiny projection neurons represent ~90% of total neurons in the striatum, and aspiny interneurons represent ~10%. Calbindin labels nearly all projection neurons, whereas among interneurons, parvalbumin labels 40-50%, and nNOS labels 10-20% (Kawaguchi et al., 1995). These three antibodies label distinct subpopulations of neurons, with only a small percentage of interneurons showing colocalization of calbindin and nNOS immunoreactivity (Bennett and Bolam, 1993). The numbers of parvalbumin-, nNOS-, and calbindin-immunoreactive neurons were compared in tissue areas surrounding injected fA and sA at 30 d after injection and in the normal (noninjected) striatum (Figs. 7, 8). Compared with levels in both the sA injection area and the normal striatum, a significant decrease in the number of parvalbumin-immunoreactive neurons is observed in the areas 0-125 µm (51% reduction) and 126-250 µm (24% reduction) from the margin of the astrogliosis surrounding the injected fA (Figs. 7, 8). Similarly, fA induces a significant decrease in nNOS-immunoreactive neurons in the area 0-125 µm from the margin of the injection track compared with both the sA injection area and the normal striatum (46% reduction). In contrast, no significant decrease in the number of calbindin-immunoreactive neurons is observed in tissue areas surrounding fA or sA injection compared with the normal striatum (Fig. 8).

View larger version (86K): [in this window] [in a new window]   Figure 7.   Injection of fA induces a reduction in the number of parvalbumin-immunoreactive neurons. A, B, Anti-parvalbumin and anti-GFAP were used to label parvalbumin neurons (blue) and the astrogliosis (yellow) surrounding sA and fA needle tracks. A, C, Note that in tissue areas surrounding injected sA, parvalbumin neurons are evenly distributed outward from the margin of the astrogliosis. B, D, In contrast, a significant reduction in the number of parvalbumin neurons is observed near the astrogliosis surrounding injected fA (red; image of fA from a serial section labeled with anti-A). Images of parvalbumin neurons and astrocytes were taken from the same double-labeled tissue sections and are Kalman averages of a single optical section acquired using a 10× lens. Scale bar, 125 µm.

View larger version (32K): [in this window] [in a new window]   Figure 8.   Injected fA induces a reduction in the number of parvalbumin- and nNOS- but not calbindin-immunoreactive neurons. A-C, Subpopulations of striatal neurons were labeled on separate tissue sections using anti-parvalbumin, anti-nNOS, or anti-calbindin, and on all sections the needle track was double-labeled using anti-GFAP. Numbers of parvalbumin-, nNOS-, and calbindin-immunoreactive neurons are compared over identical areas around sA and fA needle tracks at 30 d after injection and in the normal (noninjected) striatum. A, A significant reduction in the number of parvalbumin-immunoreactive neurons is observed up to 250 µm from the margin of the fA injection track relative to the sA injection track and normal striatum. B, In the fA injection area, a significant reduction is also observed in the number of nNOS-immunoreactive neurons up to 125 µm from the injection track relative to the sA injection track and normal striatum. C, In contrast, no significant difference in the number of calbindin-immunoreactive neurons is observed when comparing fA and sA injection areas and the normal striatum. (**p < 0.01; *p < 0.05)

	DISCUSSION

Top Abstract Introduction Materials & Methods Results Discussion References

Stability of fibrillar A in the rat CNS in vivo

In the present study, injected fA is remarkably stable in the rat CNS in vivo, contrasting with previous reports that noted an apparent lack of A stability after injection or infusion. An early review of AD animal models (Price et al., 1992) reported that sA or its fragments injected into various brain regions were either neurotoxic, nontoxic, or neurotrophic depending on the aggregation state of the peptide. One consistent feature of these studies, however, was the difficulty encountered in visualizing A after injection of sA. In the present study, sA was not stable in vivo, appearing to be cleared rapidly from the site of injection. Rapid clearance of sA may also explain the inability to visualize injected A in the previous studies.

Aggregates of injected fA, which are of comparable size to AD plaque cores found in the human brain, are highly stable in the present study. The stability of fA contrasts with a previous study that showed that human AD plaque cores injected into the rat brain were cleared by microglia from their site of injection within 30 d (Frautschy et al., 1992). This difference in stability between fA and AD plaque cores may be explained in part by the presence of a variety of extracellular, non-A components in the plaque cores obtained from humans. For example, complement proteins C1q, C4d, and C3d, which help facilitate phagocytosis of foreign material by macrophages and microglia, are bound to A in AD plaques (McGeer and McGeer, 1996). The presence of these proteins and other non-A components in the injected plaque cores may explain their rapid clearance from the rat brain in the previous study. In contrast, injected fA aggregates that remain stable in the rat striatum up to 30 d after injection are composed of synthetic A without any non-A components.

Injection of fibrillar A induces a differential response in microglia and astrocytes

In the present study, fA of a known quantity, size range, and fibrillar character was injected into one striatum, with injections of sA or vehicle made into the contralateral striatum. Using this model system, we demonstrate that fA alone is sufficient to induce a marked gliosis and iNOS induction in microglia and astrocytes in the rat brain in vivo. Although it cannot be excluded that, once in the brain, A may be interacting with other endogenous, plaque-associated components to exert its effects, our results demonstrate that injection of synthetic fA alone is sufficient to cause an increase in iNOS expression and to induce a marked gliosis similar to that observed in the human AD brain (Itagaki et al., 1989; Uchihara et al., 1995). Previous reports have suggested that iNOS expression may serve as an index of reactive gliosis (Murphy et al., 1993; Brosnan et al., 1994); thus, the present results strongly suggest that injection of fA activates both microglia and astrocytes. One surprising observation in the present study is a low level of iNOS immunoreactivity present in a small minority of microglia and astrocytes in the normal (noninjected) striatum. A recent study (Wong et al., 1996) reported no detectable iNOS gene expression in the normal (noninduced) rat brain. The low level of iNOS immunoreactivity in the normal striatum may be caused by slight cross-reactivity between the iNOS antibody and other agents in the striatum.

In contrast to injections of fA, contralateral injection of sA produces no significant increase in gliosis and iNOS expression above that observed for injection of vehicle alone. One reason for the lack of sA-induced gliosis may be that sA is rapidly cleared from brain parenchyma, suggested here by the fact that 30 d after sA injection, A immunofluorescence is only detected in a minority of microglia surrounding the needle track. The total amount of A present within these microglia is a small fraction of the total sA originally injected. Furthermore, the A present in microglia is neither Congo red-birefringent nor thioflavin S-positive, suggesting that it is not in a fibrillar form. Together, these results suggest that although sA may be neurotoxic in vitro, in the rat CNS in vivo, injected sA is cleared rapidly and does not induce a sustained glial response that characterizes acute and subchronic neurotoxicity (Gramsbergen and van den Berg, 1994; O'Callaghan et al., 1995).

Although both microglia and astrocytes show a dramatic upregulation of iNOS expression in response to injection of fA, there are marked spatial and morphological differences in the microglia and astrocyte responses to fA. Whereas microglia surround and phagocytize fA, astrocytes show no evidence of A phagocytosis but rather form a virtual wall between microglia containing fA and the surrounding neurons. Previous studies of human AD tissue (Itagaki et al., 1989; Uchihara et al., 1995) and the brains of mice overexpressing a mutant APP gene (Games et al., 1995) have also noted that reactive microglia are concentrated toward the center of AD plaques, whereas reactive astrocytes are present at the margins of plaques. Microglia containing intracellular A have been noted in AD brain (Akiyama et al., 1996), but these microglia lack detectable mRNA encoding A, suggesting an extracellular A origin (Scott et al., 1993). Similar findings have also been noted in vitro, where microglia have been shown to scavenge and accumulate A intracellularly (Frackowiak et al., 1992; Shaffer et al., 1995; Ard et al., 1996; Paresce et al., 1996), whereas astrocytes envelop and wall-off fA (Canning et al., 1993; Pike et al., 1994; DeWitt and Silver, 1996).

A-induced neuronal loss

In the current study, no significant difference in the number of calbindin-immunoreactive projection neurons was observed when comparing fA and sA injection areas and the normal striatum. In the AD striatum, the density of calbindin neurons has been shown previously not to differ significantly from that of normal controls (Selden et al., 1994). The current findings differ, however, from previous studies that showed a decrease in calbindin immunoreactivity in AD versus normal cortex (Ferrer et al., 1993; Nishiyama et al., 1993). In contrast, the number of parvalbumin- and nNOS-immunoreactive interneurons in the current study is significantly reduced in the fA injection area compared with the sA injection area and the normal striatum. Previous studies have shown that parvalbumin neurons in the rat striatum are more sensitive to excitotoxic injury than are calbindin neurons (Waldvogel et al., 1991). Although the results of the current study strongly suggest that fA induces a selective loss of neurons in the rat striatum, this effect could also be explained by a selective downregulation of parvalbumin and nNOS in neurons surrounding the injected fA. A1-40, the peptide length examined in the present study, has also been shown to cause glial-induced inhibition of neurite outgrowth in vitro (Canning et al., 1993) and to reduce numbers of choline acetyltransferase-immunoreactive neurons after injection in vivo (Giovannelli et al., 1995).

Mechanisms of A toxicity

After injection of fA, microglia and astrocytes rapidly separate fA from the surrounding neuropil, suggesting that A-induced neurotoxicity may not result from direct contact between A fibrils and surrounding neurons. If fA is not directly toxic to neurons, how might the intervening glia mediate fA toxicity? Recent studies have demonstrated that the receptor for advanced glycation end products (RAGE) and class A and B scavenger receptors on microglia bind A, which leads to microglial activation (El Khoury et al., 1996; Paresce et al., 1996; Yan et al., 1996). Glial activation, in turn, results in enhanced expression of a variety of bioactive molecules, including neurotoxic phenolic amines, cytokines, growth factors, protease inhibitors, adhesion molecules, and nitric oxide (Boje and Arora, 1992; Dickson et al., 1992; Ishii and Haga, 1992; Haga et al., 1993; Giulian et al., 1995; Mrak et al., 1995). Of particular interest is a recent study (Giulian et al., 1996) showing that human A1-40 and A1-42, but not rodent A, induce microglial adherence of A and killing of neurons in vitro. This finding, together with those of the present study in vivo, underscores the importance of using the human A peptide to induce neuronal toxicity in rodent models of AD.

A-induced NOS expression and NO production in cultured microglia and macrophages have also been reported previously (Klegeris et al., 1994; Goodwin et al., 1995; Meda et al., 1995), and NOS induction has also been linked to neuronal impairment and death in several neurological disorders involving multiple sclerosis and acquired immunodeficiency syndrome dementia (Bo et al., 1994; Adamson et al., 1996). The present study demonstrates that fA induces neuronal loss and a significant increase in iNOS expression by microglia and astrocytes in vivo, suggesting that it is the release of bioactive molecules like nitric oxide by microglia and astrocytes, rather than direct contact between A fibrils and neurons, that mediates A neurotoxicity in AD. Note, however, that the expression of NOS by human microglia remains controversial, because evidence supporting induction of reactive nitrogen species in human microglia seems strongly dependent on the experimental methodologies used (Brosnan et al., 1994).

A critical question that must be addressed in examining any animal model of a human disease is how well the animal model mimics the mechanisms and ultimate pathology observed in the human disease. Clearly, there are differences between the present rat model and human AD. First, whereas in the present study gliosis and pathology are observed over a time course of 30 d, in human AD the time course is on the order of decades. Second, the amyloid load per unit of brain area is generally higher and the amyloid distribution more extensive in the human AD brain than in our rat model. However, a key difficulty in addressing the mechanisms of pathology in human AD is that one rarely looks at human brain tissue at the initiation of the disease but rather examines the AD brain at the end stage of the disease, long after the initial mechanisms of pathology occur. A major advantage of the present rat model of fA-induced gliosis and neurotoxicity is that it provides a time- and space-compressed view of the initial changes that fA induces in the CNS in vivo. Thus, determining how glia serve as intermediaries in the apparent fA-induced neurotoxicity observed in the present model should shed significant light on the mechanisms of fA-induced neurotoxicity and allow one to test whether therapeutic interventions can block this effect.

	FOOTNOTES

Received Aug. 18, 1997; revised Dec. 16, 1997; accepted Dec. 31, 1997.

This work was supported by National Institutes of Health Grants AG11852, NS23970, and AG12853, by the Veterans Administration Merit Review, and by Alzheimer's Association Grant PRG94-194. We thank Dr. Dennis Selkoe for the contribution of anti-A R1282 and Evelyn Stimson for preparation of the ¹²⁵I-A tracer.

Correspondence should be addressed to Dr. Patrick W. Mantyh, Department of Preventive Sciences, University of Minnesota, 515 Delaware Street, Minneapolis, MN 55455. 

	REFERENCES

Top Abstract Introduction Materials & Methods Results Discussion References

• Adamson DC, Wildemann B, Sasaki M, Glass JD, McArthur JC, Christov VI, Dawson TM, Dawson VL (1996) Immunologic NO synthase-elevation in severe AIDS dementia and induction by HIV-1 Gp41. Science 274:1917-1921[Abstract/Free Full Text].
• Akiyama H, Schwab C, Kondo H, Mori H, Kametani F, Ikeda K, McGeer PL (1996) Granules in glial cells of patients with Alzheimer's disease are immunopositive for C-terminal sequences of beta-amyloid protein. Neurosci Lett 206:169-172[Web of Science][Medline].
• Ard MD, Cole GM, Wei J, Mehrle AP, Fratkin JD (1996) Scavenging of Alzheimer's amyloid beta-protein by microglia in culture. J Neurosci Res 43:190-202[Web of Science][Medline].
• Barron KD (1995) The microglial cell. A historical review. J Neurol Sci 134:57-68.
• Bennett BD, Bolam JP (1993) Two populations of calbindin D28k-immunoreactive neurones in the striatum of the rat. Brain Res 610:305-310[Web of Science][Medline].
• Benson JR, Louie PC, Bradshaw RA (1981) Amino acid analysis of peptides. In: The peptides, Vol 4 (Gross E, Mienhofer J, eds), pp 217-260. New York: Academic.
• Bo L, Dawson TM, Wesselingh S, Mork S, Choi S, Kong PA, Hanley D, Trapp BD (1994) Induction of nitric oxide synthase in demyelinating regions of multiple sclerosis brains. Ann Neurol 36:778-786[Web of Science][Medline].
• Boje KM, Arora PK (1992) Microglial-produced nitric oxide and reactive nitrogen oxides mediate neuronal cell death. Brain Res 587:250-256[Web of Science][Medline].
• Brelje TC, Wessendorf M, Sorenson RL (1993) Multicolor laser scanning confocal immunofluorescence microscopy: practical application and limitations. In: Methods in cell biology, Vol 38 (Matsumoto B, ed), pp 97-181. San Diego: Academic.
• Brosnan CF, Battistini L, Raine CS, Dickson DW, Casadevall A, Lee SC (1994) Reactive nitrogen intermediates in human neuropathology: an overview. Dev Neurosci 16:152-161[Web of Science][Medline].
• Busciglio J, Gabuzda DH, Matsudaira P, Yankner BA (1993) Generation of beta-amyloid in the secretory pathway in neuronal and nonneuronal cells. Proc Natl Acad Sci USA 90:2092-2096[Abstract/Free Full Text].
• Bush AI, Pettingell WH, Multhaup G, Paradis M, Vonsattel JP, Gusella JF, Beyreuther K, Masters CL, Tanzi RE (1994) Rapid induction of Alzheimer A beta amyloid formation by zinc. Science 265:1464-1467[Abstract/Free Full Text].
• Canning DR, McKeon RJ, DeWitt DA, Perry G, Wujek JR, Frederickson RC, Silver J (1993) Beta-amyloid of Alzheimer's disease induces reactive gliosis that inhibits axonal outgrowth. Exp Neurol 124:289-298[Web of Science][Medline].
• Citron M, Oltersdorf T, Haass C, McConlogue L, Hung AY, Seubert P, Vigo-Pelfrey C, Lieberburg I, Selkoe DJ (1992) Mutation of the beta-amyloid precursor protein in familial Alzheimer's disease increases beta-protein production. Nature 360:672-674[Medline].
• Cummings BJ, Cotman CW (1995) Image analysis of beta-amyloid load in Alzheimer's disease and relation to dementia severity. Lancet 346:1524-1528[Web of Science][Medline].
• DeWitt DA, Silver J (1996) Regenerative failure: a potential mechanism for neuritic dystrophy in Alzheimer's disease. Exp Neurol 142:103-110[Web of Science][Medline].
• Dickson DW, Ksiezak-Reding H, Liu WK, Davies P, Crowe A, Yen SH (1992) Immunocytochemistry of neurofibrillary tangles with antibodies to subregions of tau protein: identification of hidden and cleaved tau epitopes and a new phosphorylation site. Acta Neuropathol (Berl) 84:596-605[Medline].
• Eddleston M, Mucke L (1993) Molecular profile of reactive astrocytes-implications for their role in neurologic disease. Neuroscience 54:15-36[Web of Science][Medline].
• El Khoury J, Hickman SE, Thomas CA, Cao L, Silverstein SC, Loike JD (1996) Scavenger receptor-mediated adhesion of microglia to beta-amyloid fibrils. Nature 382:716-719[Medline].
• Esler WP, Stimson ER, Jennings JM, Ghilardi JR, Mantyh PW, Maggio JE (1996) Zinc-induced aggregation of human and rat beta-amyloid peptides in vitro. J Neurochem 66:723-732[Web of Science][Medline].
• Esler WP, Stimson ER, Ghilardi JR, Felix AM, Lu Y, Vinters HV, Mantyh PW, Maggio JE (1997) A-beta deposition inhibitor screen using synthetic amyloid. Nature Biotech 15:258-263. [Web of Science][Medline]
• Evans KC, Berger EP, Cho CG, Weisgraber KH, Lansbury Jr PT (1995) Apolipoprotein E is a kinetic but not a thermodynamic inhibitor of amyloid formation: implications for the pathogenesis and treatment of Alzheimer disease. Proc Natl Acad Sci USA 92:763-767[Abstract/Free Full Text].
• Ferrer I, Tunon T, Soriano E, del Rio A, Iraizoz I, Fonseca M, Guionnet N (1993) Calbindin D-28k immunoreactivity in the temporal neocortex in patients with Alzheimer's disease. Clin Neuropathol 12:53-58[Web of Science][Medline].
• Frackowiak J, Wisniewski HM, Wegiel J, Merz GS, Iqbal K, Wang KC (1992) Ultrastructure of the microglia that phagocytose amyloid and the microglia that produce beta-amyloid fibrils. Acta Neuropathol (Berl) 84:225-233[Medline].
• Fraser PE, Nguyen JT, Chin DT, Kirschner DA (1992) Effects of sulfate ions on Alzheimer beta/A4 peptide assemblies: implications for amyloid fibril-proteoglycan interactions. J Neurochem 59:1531-1540[Web of Science][Medline].
• Frautschy SA, Cole GM, Baird A (1992) Phagocytosis and deposition of vascular beta-amyloid in rat brains injected with Alzheimer beta-amyloid. Am J Pathol 140:1389-1399[Abstract].
• Games D, Adams D, Alessandrini R, Barbour R, Berthelette P, Blackwell C, Carr T, Clemens J, Donaldson T, Gillespie F, Guido T, Hagopian S, Johnson-Wood K, Khan K, Lee M, Leibowitz P, Lieberburg I, Little S, Masliah E, McConlogue L, Montoya-Zavala M, Mucke L, Paganini L, Penniman E, Power M, Schenk D, Seubert P, Snyder B, Soriano F, Tan H, Vitale J, Wadsworth S, Wolozin B, Zhao J (1995) Alzheimer-type neuropathology in transgenic mice overexpressing V717F -amyloid precursor protein. Nature 373:523-527[Medline].
• Giovannelli L, Casamenti F, Scali C, Bartolini L, Pepeu G (1995) Differential effects of amyloid peptides -(1-40) and -(25-35) injections into the rat nucleus basalis. Neuroscience 66:781-792[Web of Science][Medline].
• Giulian D, Haverkamp LJ, Li J, Karshin WL, Yu J, Tom D, Li X, Kirkpatrick JB (1995) Senile plaques stimulate microglia to release a neurotoxin found in Alzheimer brain. Neurochem Int 27:119-137[Web of Science][Medline].
• Giulian D, Haverkamp LJ, Yu JH, Karshin W, Tom D, Li J, Kirkpatrick J, Kuo YM, Roher AE (1996) Specific domains of beta-amyloid from Alzheimer plaques elicit neuron killing in human microglia. J Neurosci 16:6021-6037[Abstract/Free Full Text].
• Glenner GG, Wong CW (1984) Alzheimer's disease and Down's syndrome: sharing of a unique cerebrovascular amyloid fibril protein. Biochem Biophys Res Commun 122:1131-1135[Web of Science][Medline].
• Goate A, Chartier-Harlin MC, Mullan M, Brown J, Crawford F, Fidani L, Giuffra L, Haynes A, Irving N, James L, Mant R, Newton P, Rooke K, Roques P, Talbot C, Pericak-Vance M, Roses A, Williamson R, Rossor M, Owen M, Hardy J (1991) Segregation of a missense mutation in the amyloid precursor protein gene with familial Alzheimer's disease. Nature 349:704-706[Medline].
• Goodwin JL, Uemura E, Cunnick JE (1995) Microglial release of nitric oxide by the synergistic action of beta-amyloid and IFN-gamma. Brain Res 692:207-214[Web of Science][Medline].
• Gramsbergen JB, van den Berg KJ (1994) Regional and temporal profiles of calcium accumulation and glial fibrillary acidic protein levels in rat brain after systemic injection of kainic acid. Brain Res 667:216-228[Web of Science][Medline].
• Haass C, Schlossmacher MG, Hung AY, Vigo-Pelfrey C, Mellon A, Ostaszewski BL, Lieberburg I, Koo EH, Schenk D, Teplow DB, Selkoe DJ (1992) Amyloid beta-peptide is produced by cultured cells during normal metabolism. Nature 359:322-325[Medline].
• Haga S, Ikeda K, Sato M, Ishii T (1993) Synthetic Alzheimer amyloid beta/A4 peptides enhance production of complement C3 component by cultured microglial cells. Brain Res 601:88-94[Web of Science][Medline].
• Harrigan MR, Kunkel DD, Nguyen LB, Malouf AT (1995) Beta amyloid is neurotoxic in hippocampal slice cultures. Neurobiol Aging 16:779-789[Web of Science][Medline].
• Ishii T, Haga S (1992) Complements, microglial cells and amyloid fibril formation. Res Immunol 143:614-616[Web of Science][Medline].
• Itagaki S, McGeer PL, Akiyama H, Zhu S, Selkoe D (1989) Relationship of microglia and astrocytes to amyloid deposits of Alzheimer disease. J Neuroimmunol 24:173-182[Web of Science][Medline].
• Jarrett JT, Lansbury Jr PT (1992) Amyloid fibril formation requires a chemically discriminating nucleation event: studies of an amyloidogenic sequence from the bacterial protein OsmB. Biochemistry 31:12345-12352[Medline].
• Jarrett JT, Lansbury Jr PT (1993) Seeding "one-dimensional crystallization" of amyloid: a pathogenic mechanism in Alzheimer's disease and scrapie? Cell 73:1055-1058[Web of Science][Medline].
• Jarrett JT, Berger EP, Lansbury Jr PT (1993) The carboxy terminus of the beta amyloid protein is critical for the seeding of amyloid formation: implications for the pathogenesis of Alzheimer's disease. Biochemistry 32:4693-4697[Medline].
• Jarrett JT, Costa PR, Griffin RG, Lansbury Jr PT (1994) Models of the beta protein C-terminus: differences in amyloid structure may lead to segregation of "long" and "short" fibrils. J Am Chem Soc 116:9741-9742.
• Kang J, Lemaire HG, Unterbeck A, Salbaum JM, Masters CL, Grzeschik KH, Multhaup G, Beyreuther K, Muller-Hill B (1987) The precursor of Alzheimer's disease amyloid A4 protein resembles a cell-surface receptor. Nature 325:733-736[Medline].
• Kawaguchi Y, Wilson CJ, Augood SJ, Emson PC (1995) Striatal interneurones: chemical, physiological and morphological characterization. Trends Neurosci 18:527-535[Web of Science][Medline].
• Kelly JF, Furukawa K, Barger SW, Rengen MR, Mark RJ, Blanc EM, Roth GS, Mattson MP (1996) Amyloid beta-peptide disrupts carbachol-induced muscarinic cholinergic signal transduction in cortical neurons. Proc Natl Acad Sci USA 93:6753-6758[Abstract/Free Full Text].
• Kennedy WR, Wendelschafer-Crabb G, Brelje TC (1994) Innervation and vasculature of human sweat glands: an immunohistochemistry-laser scanning confocal fluorescence microscopy study. J Neurosci 14:6825-6833[Abstract].
• Kirschner DA, Abraham C, Selkoe DJ (1986) X-ray diffraction from intraneuronal paired helical filaments and extraneuronal amyloid fibers in Alzheimer disease indicates cross-beta conformation. Proc Natl Acad Sci USA 83:503-507[Abstract/Free Full Text].
• Kirschner DA, Inouye H, Duffy LK, Sinclair A, Lind M, Selkoe DJ (1987) Synthetic peptide homologous to beta protein from Alzheimer disease forms amyloid-like fibrils in vitro. Proc Natl Acad Sci USA 84:6953-6957[Abstract/Free Full Text].
• Klegeris A, Walker DG, McGeer PL (1994) Activation of macrophages by Alzheimer beta amyloid peptide. Biochem Biophys Res Commun 199:984-991[Web of Science][Medline].
• Koh JY, Yang LL, Cotman CW (1990) Beta-amyloid protein increases the vulnerability of cultured cortical neurons to excitotoxic damage. Brain Res 533:315-320[Web of Science][Medline].
• Ma J, Yee A, Brewer Jr HB, Das S, Potter H (1994) Amyloid-associated proteins alpha 1-antichymotrypsin and apolipoprotein E promote assembly of Alzheimer beta-protein into filaments. Nature 372:92-94[Medline].
• Mantyh PW, Ghilardi JR, Rogers S, DeMaster E, Allen CJ, Stimson ER, Maggio JE (1993) Aluminum, iron, and zinc ions promote aggregation of physiological concentrations of beta-amyloid peptide. J Neurochem 61:1171-1174[Web of Science][Medline].
• Mattson MP, Cheng B, Davis D, Bryant K, Lieberburg I, Rydel RE (1992) Beta-amyloid peptides destabilize calcium homeostasis and render human cortical neurons vulnerable to excitotoxicity. J Neurosci 12:376-389[Abstract].
• McGeer PL, McGeer EG (1996) Anti-inflammatory drugs in the fight against Alzheimer's disease. Ann NY Acad Sci 777:213-220[Web of Science][Medline].
• Meda L, Cassatella MA, Szendrei GI, Otvos Jr L, Baron P, Villalba M, Ferrari D, Rossi F (1995) Activation of microglial cells by beta-amyloid protein and interferon-gamma. Nature 374:647-650[Medline].
• Mrak RE, Sheng JG, Griffin WS (1995) Glial cytokines in Alzheimer's disease: review and pathogenic implications. Hum Pathol 26:816-823[Web of Science][Medline].
• Murphy S, Simmons ML, Agullo L, Garcia A, Feinstein DL, Galea E, Reis DJ, Minc-Golomb D, Schwartz JP (1993) Synthesis of nitric oxide in CNS glial cells. Trends Neurosci 16:323-328[Web of Science][Medline].
• Nishiyama E, Ohwada J, Iwamoto N, Arai H (1993) Selective loss of calbindin D28K-immunoreactive neurons in the cortical layer II in brains of Alzheimer's disease: a morphometric study. Neurosci Lett 163:223-226[Web of Science][Medline].
• O'Callaghan JP, Jensen KF, Miller DB (1995) Quantitative aspects of drug and toxicant-induced astrogliosis. Neurochem Int 26:115-124[Web of Science][Medline].
• Paresce DM, Ghosh RN, Maxfield FR (1996) Microglial cells internalize aggregates of the Alzheimer's disease amyloid beta-protein via a scavenger receptor. Neuron 17:553-565[Web of Science][Medline].
• Paxinos G, Watson C (1986) In: The rat brain in stereotaxic coordinates. North Ryde, New South Wales, Australia: Academic.
• Pike CJ, Walencewicz AJ, Glabe CG, Cotman CW (1991a) Aggregation-related toxicity of synthetic beta-amyloid protein in hippocampal cultures. Eur J Pharmacol 207:367-368[Web of Science][Medline].
• Pike CJ, Walencewicz AJ, Glabe CG, Cotman CW (1991b) In vitro aging of beta-amyloid protein causes peptide aggregation and neurotoxicity. Brain Res 563:311-314[Web of Science][Medline].
• Pike CJ, Burdick D, Walencewicz AJ, Glabe CG, Cotman CW (1993) Neurodegeneration induced by beta-amyloid peptides in vitro: the role of peptide assembly state. J Neurosci 13:1676-1687[Abstract].
• Pike CJ, Cummings BJ, Monzavi R, Cotman CW (1994) Beta-amyloid-induced changes in cultured astrocytes parallel reactive astrocytosis associated with senile plaques in Alzheimer's disease. Neuroscience 63:517-531[Web of Science][Medline].
• Pike CJ, Walencewicz-Wasserman AJ, Kosmoski J, Cribbs DH, Glabe CG, Cotman CW (1995) Structure-activity analyses of beta-amyloid peptides: contributions of the beta 25-35 region to aggregation and neurotoxicity. J Neurochem 64:253-265[Web of Science][Medline].
• Price DL, Borchelt DR, Walker LC, Sisodia SS (1992) Toxicity of synthetic A peptides and modeling of Alzheimer's disease. Neurobiology of Aging 13:623-625[Web of Science][Medline].
• Sanan DA, Weisgraber KH, Russell SJ, Mahley RW, Huang D, Saunders A, Schmechel D, Wisniewski T, Frangione B, Roses AD, Strittmatter WJ (1994) Apolipoprotein E associates with beta amyloid peptide of Alzheimer's disease to form novel monofibrils. Isoform apoE4 associates more efficiently than apoE3. J Clin Invest 94:860-869.
• Scheuner D, Eckman C, Jensen M, Song X, Citron M, Suzuki N, Bird TD, Hardy J, Hutton M, Kukull W, Larson E, Levy-Lahad E, Viitanen M, Peskind E, Poorkaj P, Schellenberg G, Tanzi R, Wasco W, Lannfelt L, Selkoe D, Younkin S (1996) Secreted amyloid beta-protein similar to that in the senile plaques of Alzheimer's disease is increased in vivo by the presenilin 1 and 2 and APP mutations linked to familial Alzheimer's disease. Nat Med 2:864-870[Web of Science][Medline].
• Scott SA, Johnson SA, Zarow C, Perlmutter LS (1993) Inability to detect beta-amyloid protein precursor mRNA in Alzheimer plaque-associated microglia. Exp Neurol 121:113-118[Web of Science][Medline].
• Selden N, Geula C, Hersh L, Mesulam MM (1994) Human striatum: chemoarchitecture of the caudate nucleus, putamen and ventral striatum in health and Alzheimer's disease. Neuroscience 60:621-636[Web of Science][Medline].
• Selkoe DJ (1991) The molecular pathology of Alzheimer's disease. Neuron 6:487-498[Web of Science][Medline].
• Selkoe DJ (1994) Alzheimer's disease: a central role for amyloid. J Neuropathol Exp Neurol 53:438-447[Web of Science][Medline].
• Selkoe DJ (1997) Alzheimer's disease-genotypes, phenotype, and treatments. Science 275:630-631[Free Full Text].
• Selkoe DJ, Abraham CR (1986) Isolation of paired helical filaments and amyloid fibers from human brain. Methods Enzymol 134:388-404[Web of Science][Medline].
• Seubert P, Vigo-Pelfrey C, Esch F, Lee M, Dovey H, Davis D, Sinha S, Schlossmacher M, McCormack R, Wolfert R, Selkoe D, Lieberburg I, Schenk D (1992) Isolation and quantification of soluble Alzheimer's beta-peptide from biological fluids. Nature 359:325-327[Medline].
• Shaffer LM, Dority MD, Gupta-Bansal R, Frederickson RC, Younkin SG, Brunden KR (1995) Amyloid beta protein (A beta) removal by neuroglial cells in culture. Neurobiol Aging 16:737-745[Web of Science][Medline].
• Shoji M, Golde TE, Ghiso J, Cheung TT, Estus S, Shaffer LM, Cai XD, McKay DM, Tintner R, Frangione B, Younkin SG (1992) Production of the Alzheimer amyloid beta protein by normal proteolytic processing. Science 258:126-129[Abstract/Free Full Text].
• Soreghan B, Kosmoski J, Glabe C (1994) Surfactant properties of Alzheimer's A beta peptides and the mechanism of amyloid aggregation. J Biol Chem 269:28551-28554[Abstract/Free Full Text].
• Uchihara T, Kondo H, Akiyama H, Ikeda K (1995) Single-laser three-color immunolabeling of a histological section by laser scanning microscopy: application to senile plaque-related structures in post-mortem human brain tissue. J Histochem Cytochem 43:103-106[Abstract].
• van Gool WA, Kuiper MA, Walstra GJ, Wolters EC, Bolhuis PA (1995) Concentrations of amyloid beta protein in cerebrospinal fluid of patients with Alzheimer's disease. Ann Neurol 37:277-279[Web of Science][Medline].
• Waldvogel HJ, Faull RL, Williams MN, Dragunow M (1991) Differential sensitivity of calbindin and parvalbumin immunoreactive cells in the striatum to excitotoxins. Brain Res 546:329-335[Web of Science][Medline].
• Wisniewski T, Castano EM, Golabek A, Vogel T, Frangione B (1994) Acceleration of Alzheimer's fibril formation by apolipoprotein E in vitro. Am J Pathol 145:1030-1035[Abstract].
• Wong M-L, Rettori V, Al-Shekhlee A, Bongiorno PB, Canteros G, McCann SM, Gold PW, Licinio J (1996) Inducible nitric oxide synthase gene expression in the brain during systemic inflammation. Nat Med 2:581-584[Web of Science][Medline].
• Yan SD, Chen X, Fu J, Chen M, Zhu HJ, Roher A, Slattery T, Zhao L, Nagashima M, Morser J, Migheli A, Nawroth P, Stern D, Schmidt AM (1996) RAGE and amyloid-beta peptide neurotoxicity in Alzheimer's disease. Nature 382:685-691[Medline].
• Yankner BA, Duffy LK, Kirschner DA (1990) Neurotrophic and neurotoxic effects of amyloid beta protein: reversal by tachykinin neuropeptides. Science 250:279-282[Abstract/Free Full Text].

---

Copyright © 1998 Society for Neuroscience  0270-6474/98/1862161-13$05.00/0

This article has been cited by other articles:

				R. M. Cohen The Role of the Immune System in Alzheimer's Disease Focus, January 1, 2009; 7(1): 28 - 35. [Abstract] [Full Text] [PDF]

				C. Wang, E. Bomberg, C. Billington, A. Levine, and C. M. Kotz Brain-derived neurotrophic factor in the hypothalamic paraventricular nucleus reduces energy intake Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2007; 293(3): R1003 - R1012. [Abstract] [Full Text] [PDF]

				K. Chen, P. Iribarren, J. Huang, L. Zhang, W. Gong, E. H. Cho, S. Lockett, N. M. Dunlop, and J. M. Wang Induction of the Formyl Peptide Receptor 2 in Microglia by IFN-{gamma} and Synergy with CD40 Ligand J. Immunol., February 1, 2007; 178(3): 1759 - 1766. [Abstract] [Full Text] [PDF]

				S. Franciosi, J. K. Ryu, H. B. Choi, L. Radov, S. U. Kim, and J. G. McLarnon Broad-Spectrum Effects of 4-Aminopyridine to Modulate Amyloid beta1-42-Induced Cell Signaling and Functional Responses in Human Microglia. J. Neurosci., November 8, 2006; 26(45): 11652 - 11664. [Abstract] [Full Text] [PDF]

				S. Qin, C. Colin, I. Hinners, A. Gervais, C. Cheret, and M. Mallat System Xc- and apolipoprotein E expressed by microglia have opposite effects on the neurotoxicity of amyloid-beta peptide 1-40. J. Neurosci., March 22, 2006; 26(12): 3345 - 3356. [Abstract] [Full Text] [PDF]

				K. Chen, P. Iribarren, J. Hu, J. Chen, W. Gong, E. H. Cho, S. Lockett, N. M. Dunlop, and J. M. Wang Activation of Toll-like Receptor 2 on Microglia Promotes Cell Uptake of Alzheimer Disease-associated Amyloid beta Peptide J. Biol. Chem., February 10, 2006; 281(6): 3651 - 3659. [Abstract] [Full Text] [PDF]

				A. K. Stalder, F. Ermini, L. Bondolfi, W. Krenger, G. J. Burbach, T. Deller, J. Coomaraswamy, M. Staufenbiel, R. Landmann, and M. Jucker Invasion of Hematopoietic Cells into the Brain of Amyloid Precursor Protein Transgenic Mice J. Neurosci., November 30, 2005; 25(48): 11125 - 11132. [Abstract] [Full Text] [PDF]

				M. Kitazawa, S. Oddo, T. R. Yamasaki, K. N. Green, and F. M. LaFerla Lipopolysaccharide-Induced Inflammation Exacerbates Tau Pathology by a Cyclin-Dependent Kinase 5-Mediated Pathway in a Transgenic Model of Alzheimer's Disease J. Neurosci., September 28, 2005; 25(39): 8843 - 8853. [Abstract] [Full Text] [PDF]

				R.A Quinlan and B Straughan Decay bounds in a model for aggregation of microglia: application to Alzheimer's disease senile plaques Proc R Soc A, September 8, 2005; 461(2061): 2887 - 2897. [Abstract] [Full Text] [PDF]

				B. G. Ramirez, C. Blazquez, T. G. del Pulgar, M. Guzman, and M. L. de Ceballos Prevention of Alzheimer's Disease Pathology by Cannabinoids: Neuroprotection Mediated by Blockade of Microglial Activation J. Neurosci., February 23, 2005; 25(8): 1904 - 1913. [Abstract] [Full Text] [PDF]

				A. Cordle and G. Landreth 3-Hydroxy-3-Methylglutaryl-Coenzyme A Reductase Inhibitors Attenuate {beta}-Amyloid-Induced Microglial Inflammatory Responses J. Neurosci., January 12, 2005; 25(2): 299 - 307. [Abstract] [Full Text] [PDF]

				V. Laporte, Y. Lombard, R. Levy-Benezra, C. Tranchant, P. Poindron, and J.-M. Warter Uptake of A{beta} 1-40- and A{beta} 1-42-coated yeast by microglial cells: a role for LRP J. Leukoc. Biol., August 1, 2004; 76(2): 451 - 461. [Abstract] [Full Text] [PDF]

				J. B. El Khoury, K. J. Moore, T. K. Means, J. Leung, K. Terada, M. Toft, M. W. Freeman, and A. D. Luster CD36 Mediates the Innate Host Response to {beta}-Amyloid J. Exp. Med., June 16, 2003; 197(12): 1657 - 1666. [Abstract] [Full Text] [PDF]

				A. Klegeris and P. L. McGeer Toxicity of human monocytic THP-1 cells and microglia toward SH-SY5Y neuroblastoma cells is reduced by inhibitors of 5-lipoxygenase and its activating protein FLAP J. Leukoc. Biol., March 1, 2003; 73(3): 369 - 378. [Abstract] [Full Text] [PDF]

				K. J. Moore, J. El Khoury, L. A. Medeiros, K. Terada, C. Geula, A. D. Luster, and M. W. Freeman A CD36-initiated Signaling Cascade Mediates Inflammatory Effects of beta -Amyloid J. Biol. Chem., November 27, 2002; 277(49): 47373 - 47379. [Abstract] [Full Text] [PDF]

				M. H. Mohajeri, K. Saini, J. G. Schultz, M. A. Wollmer, C. Hock, and R. M. Nitsch Passive Immunization against beta -Amyloid Peptide Protects Central Nervous System (CNS) Neurons from Increased Vulnerability Associated with an Alzheimer's Disease-causing Mutation J. Biol. Chem., August 30, 2002; 277(36): 33012 - 33017. [Abstract] [Full Text] [PDF]

				M. E. Bamberger and G. E. Landreth Inflammation, Apoptosis, and Alzheimer's Disease Neuroscientist, June 1, 2002; 8(3): 276 - 283. [Abstract] [PDF]

				M. T. Heneka, E. Galea, V. Gavriluyk, L. Dumitrescu-Ozimek, J. Daeschner, M. K. O'Banion, G. Weinberg, T. Klockgether, and D. L. Feinstein Noradrenergic Depletion Potentiates beta -Amyloid-Induced Cortical Inflammation: Implications for Alzheimer's Disease J. Neurosci., April 1, 2002; 22(7): 2434 - 2442. [Abstract] [Full Text] [PDF]

				P. T. Jantzen, K. E. Connor, G. DiCarlo, G. L. Wenk, J. L. Wallace, A. M. Rojiani, D. Coppola, D. Morgan, and M. N. Gordon Microglial Activation and beta -Amyloid Deposit Reduction Caused by a Nitric Oxide-Releasing Nonsteroidal Anti-Inflammatory Drug in Amyloid Precursor Protein Plus Presenilin-1 Transgenic Mice J. Neurosci., March 15, 2002; 22(6): 2246 - 2254. [Abstract] [Full Text] [PDF]

				J. Y.H. Chan, L.-L. Wang, K. L.H. Wu, and S. H.H. Chan Reduced Functional Expression and Molecular Synthesis of Inducible Nitric Oxide Synthase in Rostral Ventrolateral Medulla of Spontaneously Hypertensive Rats Circulation, October 2, 2001; 104(14): 1676 - 1681. [Abstract] [Full Text] [PDF]

				A. Stephan, S. Laroche, and S. Davis Generation of Aggregated {beta}-Amyloid in the Rat Hippocampus Impairs Synaptic Transmission and Plasticity and Causes Memory Deficits J. Neurosci., August 1, 2001; 21(15): 5703 - 5714. [Abstract] [Full Text] [PDF]

				K. ISHII, F. MUELHAUSER, U. LIEBL, M. PICARD, S. KÜHL, B. PENKE, T. BAYER, M. WIESSLER, M. HENNERICI, K. BEYREUTHER, et al. Subacute NO generation induced by Alzheimer's {beta}-amyloid in the living brain: reversal by inhibition of the inducible NO synthase FASEB J, August 1, 2000; 14(11): 1485 - 1489. [Abstract] [Full Text]

				C. K. Combs, D. E. Johnson, J. C. Karlo, S. B. Cannady, and G. E. Landreth Inflammatory Mechanisms in Alzheimer's Disease: Inhibition of beta -Amyloid-Stimulated Proinflammatory Responses and Neurotoxicity by PPARgamma Agonists J. Neurosci., January 15, 2000; 20(2): 558 - 567. [Abstract] [Full Text] [PDF]

				M. T. Fitch, C. Doller, C. K. Combs, G. E. Landreth, and J. Silver Cellular and Molecular Mechanisms of Glial Scarring and Progressive Cavitation: In Vivo and In Vitro Analysis of Inflammation-Induced Secondary Injury after CNS Trauma J. Neurosci., October 1, 1999; 19(19): 8182 - 8198. [Abstract] [Full Text] [PDF]

				D. W. Dickson Microglia in Alzheimer's Disease and Transgenic Models : How Close the Fit? Am. J. Pathol., June 1, 1999; 154(6): 1627 - 1631. [Full Text] [PDF]

				T. V. Petrova, K. T. Akama, and L. J. Van Eldik Cyclopentenone prostaglandins suppress activation of microglia: Down-regulation of inducible nitric-oxide synthase by 15-deoxy-Delta 12,14-prostaglandin J2 PNAS, April 13, 1999; 96(8): 4668 - 4673. [Abstract] [Full Text] [PDF]

				K. J. Ivins, J. K. Ivins, J. P. Sharp, and C. W. Cotman Multiple Pathways of Apoptosis in PC12 Cells. CrmA INHIBITS APOPTOSIS INDUCED BY beta -AMYLOID J. Biol. Chem., January 22, 1999; 274(4): 2107 - 2112. [Abstract] [Full Text] [PDF]

				S. A. Frautschy, D. L. Horn, J. J. Sigel, M. E. Harris-White, J. J. Mendoza, F. Yang, T. C. Saido, and G. M. Cole Protease Inhibitor Coinfusion with Amyloid beta -Protein Results in Enhanced Deposition and Toxicity in Rat Brain J. Neurosci., October 15, 1998; 18(20): 8311 - 8321. [Abstract] [Full Text] [PDF]

				N. Y. Barnes, L. Li, K. Yoshikawa, L. M. Schwartz, R. W. Oppenheim, and C. E. Milligan Increased Production of Amyloid Precursor Protein Provides a Substrate for Caspase-3 in Dying Motoneurons J. Neurosci., August 1, 1998; 18(15): 5869 - 5880. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Submit an eLetter Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (173) Citing Articles via Google Scholar Google Scholar Articles by Weldon, D. T. Articles by Mantyh, P. W. Search for Related Content PubMed PubMed Citation Articles by Weldon, D. T. Articles by Mantyh, P. W.

Home  |   Search  |   Archive  |   Subscribe  |   Contact  |   Help