The Journal of Neuroscience, 1999:RC10:1-5
RAPID COMMUNICATION
Histochemically Reactive Zinc in Plaques of the Swedish Mutant
-Amyloid Precursor Protein Transgenic Mice
Joo-Yong
Lee,
Inhee
Mook-Jung, and
Jae-Young
Koh
National Creative Research Initiative Center for the Study of CNS
Zinc and Department of Neurology, University of Ulsan College of
Medicine, Seoul 138-736, Korea
Endogenous metals such as zinc may contribute to
-amyloid (A
)
aggregation and hence the plaque formation. In the present study, we
examined brains of four Swedish mutant amyloid precursor protein (APP)
transgenic mice at 12 months of age for histochemically reactive zinc
in the plaques. Here, we report that all the Congo red (+)
mature plaques contained chelatable zinc, as demonstrated by
staining with the zinc-specific fluorescent dye
6-methoxy-8-quinolyl-para-toluenesulfonamide (TSQ). On the other hand, Congo red (
) preamyloid A
deposits were
not stained with TSQ. Interestingly, although cerebellum contained
similar degree of preamyloid A
deposits as cerebral cortex, it was
completely devoid of Congo red- or TSQ-stained mature plaques. Although
zinc from plaques was only slowly and partially removed by a specific
zinc remover, dithizone, treatment of brain sections with
heparinase-III, which degrades heparan sulfate proteoglycan (HSPG),
another major constituent of plaques, greatly fastened the zinc removal
with dithizone.
The present study has demonstrated the presence of histochemically
reactive zinc in plaques, but not preamyloid A
deposits, of the
Swedish mutant APP transgenic mice. Because preamyloid A
deposits
fail to develop into congophilic plaques in cerebellum where synaptic
vesicle zinc is deficient, the synaptic zinc may be a necessary element
in the plaque formation. In holding zinc inside plaques, HSPG may
contribute in addition to A
.
Key words:
-amyloid; Alzheimer's disease; heparan sulfate
proteoglycan; metal; cortex; cerebellum
Copyright © 1999 Society for Neuroscience 0270-6474/99/$05.00/0