How Long Does It Take for Hilar Basal Dendrites To Form on Granule Cells Following Status Epilepticus?
Abstract number :
1.024
Submission category :
Year :
2001
Submission ID :
906
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
K. Dashtipour, MD, PhD, Anatomy and Neurobiology, University of California, Irvine, CA; A.M. Wong, BS, Anatomy and Neurobiology, University of California, Irvine, CA; I. Spigelman, PhD, Division of Oral Biology and Medicine, UCLA School of Dentistry, Los
RATIONALE: Granule cells with hilar basal dendrites (HBDs) are found after status epilepticus (SE) in three rat models of temporal lobe epilepsy, but not following a single electroconvulsiveshock-induced seizure. These granule cells are commonly located at the hilar border and are newly generated granule cells. Because HBDs are postsynaptic to mossy fibers, they provide additional recurrent excitatory circuitry for granule cells in the hippocampal dentate gyrus. The aim of this study was to determine how long it takes for HBDs to form after SE.
METHODS: Pilocarpine was used to induce SE and rats were euthanized at 3, 7, 8, 15, 19 and 20 days after SE. Biocytin was injected into CA3 stratum lucidum of hippocampal slices from these rats to label granule cells with HBDs. The number, morphology and length of HBDs were analyzed at the different time points.
RESULTS: Granule cells with HBDs were detected as early as 7 and 8 days after pilocarpine-induced SE. The basal processes of granule cells from rats that survived for 3 days after pilocarpine injection were judged not to be HBDs because they were short in length and did not ramify in the hilus. The number of detected granule cells with HBDs increased at the later time points.
CONCLUSIONS: This study shows that it takes at least one week following SE for HBDs to form on granule cells. These results are consistent with the hypothesis that seizure-induced neurogenesis and hilar neuronal loss are required for the formation of HBDs on granule cells.