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

HOME  |   SEARCH  |   ARCHIVE  |   SUBSCRIBE  |   CONTACT  |   HELP

The Journal of Neuroscience, January 28, 2004, 24(4):853-864; doi:10.1523/JNEUROSCI.1619-03.2004

This Article Full Text 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 ISI 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 ISI Web of Science (25) Citing Articles via Google Scholar Google Scholar Articles by Zappone, C. A. Articles by Sloviter, R. S. Search for Related Content PubMed PubMed Citation Articles by Zappone, C. A. Articles by Sloviter, R. S.

 Previous Article  |  Next Article 

Neurobiology of Disease
Translamellar Disinhibition in the Rat Hippocampal Dentate Gyrus after Seizure-Induced Degeneration of Vulnerable Hilar Neurons

Colin A. Zappone and Robert S. Sloviter

Departments of Pharmacology and Neurology, and the Graduate Program in Neuroscience, University of Arizona College of Medicine, Tucson, Arizona 85724

Longitudinally restricted axonal projections of hippocampal granule cells suggest that transverse segments of the granule cell layer may operate independently (the "lamellar" hypothesis). Longitudinal projections of excitatory hilar mossy cells could be viewed as antithetical to lamellar function, but only if longitudinal impulse flow effectively excites distant granule cells. We, therefore, determined the effect of focal granule cell discharges on granule cells located >2 mm along the longitudinal axis. During perforant pathway stimulation in urethane-anesthetized rats, passive diffusion of the GABA_A receptor antagonist bicuculline methiodide from the tip of a glass recording electrode evoked granule cell discharges and c-Fos expression in granule cells, mossy cells, and inhibitory interneurons, within a 400 µm radius. This focally evoked activity powerfully suppressed distant granule cell-evoked responses recorded simultaneously 2.5–4.5 mm longitudinally. Three days after kainic acid-induced status epilepticus or prolonged perforant pathway stimulation, translamellar inhibition was intact in rats with <40% hilar neuron loss but was consistently abolished after extensive (>85%) hilar cell loss. Retrograde transport of Fluoro-Gold (FG) from the rostral dentate gyrus revealed that few inhibitory interneurons were among the many retrogradely labeled hilar neurons 2.5–4.5 mm longitudinally. Although many somatostatin-positive hilar interneurons effectively transported FG from the distant septum, few of these neurons transported detectable FG from much closer hippocampal injection sites. Inhibitory basket and chandelier cells also exhibited minimal longitudinal FG transport. These findings suggest that translamellar disinhibition may result from the loss of vulnerable, longitudinally projecting mossy cells and may represent a network-level mechanism underlying postinjury hippocampal dysfunction and epileptic network hyperexcitability.

Key words: lamellar hypothesis; inhibitory interneurons; hippocampus; epilepsy; c-Fos; lateral inhibition

---

Received July 18, 2003; revised November 25, 2003; accepted November 25, 2003.

This article has been cited by other articles:

				A. Carneiro, M. Assuncao, V. D. Freitas, M. M. Paula-Barbosa, and J. P. Andrade Red Wine, but not Port Wine, Protects Rat Hippocampal Dentate Gyrus Against Ethanol-Induced Neuronal Damage--Relevance of the Sugar Content Alcohol Alcohol., July 1, 2008; 43(4): 408 - 415. [Abstract] [Full Text] [PDF]

				A. K. Sharma, R. Y. Reams, W. H. Jordan, M. A. Miller, H. L. Thacker, and P. W. Snyder Mesial Temporal Lobe Epilepsy: Pathogenesis, Induced Rodent Models and Lesions Toxicol Pathol, December 1, 2007; 35(7): 984 - 999. [Abstract] [PDF]

				J. Dyhrfjeld-Johnsen, V. Santhakumar, R. J. Morgan, R. Huerta, L. Tsimring, and I. Soltesz Topological Determinants of Epileptogenesis in Large-Scale Structural and Functional Models of the Dentate Gyrus Derived From Experimental Data J Neurophysiol, February 1, 2007; 97(2): 1566 - 1587. [Abstract] [Full Text] [PDF]

				H. Xiang, H.-X. Chen, X.-X. Yu, M. A. King, and S. N. Roper Reduced Excitatory Drive in Interneurons in an Animal Model of Cortical Dysplasia J Neurophysiol, August 1, 2006; 96(2): 569 - 578. [Abstract] [Full Text] [PDF]

				L. S. Overstreet-Wadiche, D. A. Bromberg, A. L. Bensen, and G. L. Westbrook Seizures Accelerate Functional Integration of Adult-Generated Granule Cells J. Neurosci., April 12, 2006; 26(15): 4095 - 4103. [Abstract] [Full Text] [PDF]

				S. M. Moenter and R. A. DeFazio Endogenous {gamma}-Aminobutyric Acid Can Excite Gonadotropin-Releasing Hormone Neurons Endocrinology, December 1, 2005; 146(12): 5374 - 5379. [Abstract] [Full Text] [PDF]

				M. E. Calcagnotto, M. F. Paredes, T. Tihan, N. M. Barbaro, and S. C. Baraban Dysfunction of Synaptic Inhibition in Epilepsy Associated with Focal Cortical Dysplasia J. Neurosci., October 19, 2005; 25(42): 9649 - 9657. [Abstract] [Full Text] [PDF]

Home  |   Search  |   Archive  |   Subscribe  |   Contact  |   Help