Differential Expression of Calbindin (CaBP) and c-fos Immunoreactivity (IR) in Dentate Gyrus Granule Cells (GC) After Pilocarpine-Induced Status Epilepticus (SE) and Recurrent Seizures (SZ)
Abstract number :
1.001
Submission category :
Year :
2000
Submission ID :
2330
Source :
www.aesnet.org
Presentation date :
12/2/2000 12:00:00 AM
Published date :
Dec 1, 2000, 06:00 AM
Authors :
Jeffrey H Goodman, Helen E Scharfman, Helen Hayes Hosp, West Haverstraw, NY; Helen Hayes Hosp & Columbia Univ, West Haverstraw, NY
RATIONALE: GC expression of CaBP, a calcium-binding protein, has been shown to change after experimentally-induced SZ and in human epileptic tissue. We observed a differential expression of CaBP-IR within the GC layer after pilocarpine-induced SE and spontaneous SZ. We also stained for c-fos-IR to examine the possibility that differential GC activation was the reason for variations in CaBP-IR after SZ. METHODS: Adult male S-D rats (180-250g)were injected with pilocarpine (380mg/kg). Diazepam (5mg/kg) was injected 1hr after the onset of SE. Rats were perfusion-fixed 4-5hr after a spontaneous behavioral SZ. Tissue sections 40m thick were processed for CaBP-IR and c-fos-IR. Some sections were double-labeled for CaBP and c-fos. CaBP-stained tissue was also Nissl-stained to visualize cells that were not CaBP-positive. RESULTS: In rats sacrificed 4-5hr after a spontaneous SZ (n=8), the expression of CaBP-IR was altered. Within the GC layer of the septal dentate, but not the temporal dentate, CaBP-IR was greatly decreased. When present, CaBP-IR often occurred in patches, located predominantly in GCs within the middle of the layer. Often there was no staining in GCs located closest to the inner molecular layer or to the hilus. We stained for c-fos-IR to determine if this alteration in CaBP-IR was related to differential activation of the GCs by the SZ. There was no evidence of c-fos-IR in GCs in the septal hippocampus in 4/8 rats; similar to what has been reported by Mello et al., (1996). However, in the remaining 4 rats we observed a selective expression of c-fos-IR in those GCs that failed to express CaBP-IR. CONCLUSIONS: There are septotemporal and intralaminar differences in CaBP-IR within the GC layer after spontaneous SZ in pilocarpine-treated rats. The expression of c-fos-IR, precisely in those GCs that do not express CaBP-IR, suggests that differential activation of GCs during spontaneous SZ contributes to the changes in CaBP-IR. The observation that similar behavioral SZ may or may not lead to GC expression of c-fos-IR suggests that not all behavioral SZ are alike.