Relations between brain pathology and temporal lobe epilepsy.
Temporal lobe epilepsy, the most common type of epilepsy in adult humans, is characterized clinically by the progressive development of spontaneous recurrent seizures of temporal lobe origin and pathologically by hippocampal neuronal loss and mossy fiber sprouting. In this study, we sought to test the prominent hypothesis that neuronal loss and mossy fiber sprouting play a critical role in the genesis and progression of temporal lobe epilepsy. Rats receiving a single kainic acid injection experienced a single sustained episode of epileptic status with massive neuronal loss and mossy fiber sprouting, whereas rats receiving triple kainic acid injections experienced two priming episodes and one sustained episode of epileptic status with no detectable neuronal loss and mossy fiber sprouting. Early in the process of chronic seizure development, primed rats that failed to show detectable neuronal loss and mossy fiber sprouting exhibited a starting date and a frequency of spontaneous recurrent seizures similar to those of nonprimed rats that showed massive neuronal loss and mossy fiber sprouting. However, nonprimed rats displayed significantly prolonged episodes of spontaneous recurrent seizures over the whole process of chronic seizure development and more frequent severe seizures later in the process. Similar results were observed in both Fischer-344 and Wistar rats as well as in the rat pilocarpine preparation of temporal lobe epilepsy. These results fail to reveal a relation between neuronal loss-mossy fiber sprouting and the genesis of temporal lobe epilepsy but suggest that neuronal loss, mossy fiber sprouting, or both contribute to the intensification of chronic seizures.
Neuropsychiatry Research Unit, Department of Psychiatry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E4. zhangxia@duke.usask.ca
Xia
X
Zhang
Shu-Sen
SS
Cui
Amy E
AE
Wallace
Darren K
DK
Hannesson
Larry C
LC
Schmued
Deborah M
DM
Saucier
William G
WG
Honer
Michael E
ME
Corcoran
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000473:pathology* / Q000503:physiopathology; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002908:Chronic Disease; D004195:Disease Models, Animal; D018450:Disease Progression; D004833:Epilepsy, Temporal Lobe / Q000139:chemically induced / Q000473:pathology* / Q000503:physiopathology; D007608:Kainic Acid; D008032:Limbic System / Q000187:drug effects / Q000503:physiopathology; D008297:Male; D019599:Mossy Fibers, Hippocampal / Q000187:drug effects / Q000473:pathology; D009474:Neurons / Q000187:drug effects / Q000473:pathology; D010862:Pilocarpine; D051381:Rats; D011916:Rats, Inbred F344; D017208:Rats, Wistar; D011930:Reaction Time; D012008:Recurrence; D015996:Survival Rate
D010862:Pilocarpine; D007608:Kainic Acid