Mossy fiber Synaptic Reorganization and the Pattern of Sprouting 
in the Pilocarpine Epilepsy Model

J Korean Neurol Assoc > Volume 16(4); 1998 > Article

Journal of the Korean Neurological Association 1998;16(4): 547-556.

Pilocarpine 간질 모델에서 태상섬유의 신경연접 재구성 및 축삭의 발아 양상

영남대학교 의과대학 신경과학 교실

Mossy fiber Synaptic Reorganization and the Pattern of Sprouting in the Pilocarpine Epilepsy Model

Mee-Yeong Park, M.D.

Department of neurology, College of medicine, Yeungnam university.

Abstract

Background: The purpose of this study is to evaluate the synaptic reorganization and pattern of mossy fiber sprouting as a pathologic mechanism of chronic seizure in pilocarpine epilepsy model through histological alterations of hippocampus. Mathod: Sprague-Dawley, a sensitively damaged by pilocarpine stimulation, served as a experimental group(n=20). And the same dose of saline injected rats were served as a control group(n=10). They were implanted depth electrode in the hippocampus by a stereotaxic surgery, and injected pilocarpine 300mg/Kg intraperitoneally. They produced status epilepticus and the survival rats were monitored by a video-EEG monitoring system whether the spontaneous recurrent seizures occurring for more than 4 weeks. If more than 3 times spontaneous recurrent seizures were identified, then the rat hippocampus was examined by light microscope. Result: The pilocarpine injected group produced acute limbic seizure and developed to status epilepticus. The survival rats(n=10) became to chronic epilepsy state after silent period of everage 16.5 days. H＆E staining demonstrated that loss of hilar polymorphic cell with ischemic changes and destruction of CA1 with damages of pyramidal cells in hippocampal subfields. Timm stains showed mossy fiber synatic reorganization in the supragranular and intragranular layer of dentate gyrus and infrapyramidal layer of CA3 hippocampal subfieid in pilocarpine induce seizure rats.
Conclusion: These results suggest that chronic seizures in the pilocarpine epilepsy model is largely due to mossy fiber synatic reorganization, a consequence of supragranular mossy fiber sprouting. But intragranular and infrapyramidal axonal sprouting might have parts of role in synaptic reorganization. Additional research is required to determine the various patterns of axonal sprouting. Key words; Pilocarpine epilepsy model, hippocampal cell loss, intra and supragranular axonal sprouting, infrapyramidal axonal sprouting, mossy fiber synaptic reorganization.