A SHORT EPISODE OF SEIZURE ACTIVITY PROTECTS FROM STATUS EPILEPTICUS-INDUCED NEURONAL DAMAGE IN RAT-BRAIN

Kainic acid (KA)-induced status epilepticus (SE) in adult rats results in extensive neuronal damage throughout the Limbic system and the los s of selectively vulnerable neuronal populations, particularly CA3 neu rons. We investigated the effects of a short episode of seizure activi ty on neuronal death elicited by a subsequent prolonged SE episode. A short episode of seizure activity was produced by sub-cutaneous (s.c.) injection of KA followed after 1 h by pentobarbital administration. T wenty-four hours later, KA was administered again, and animals were sa crificed 3 days later. Neuronal damage was estimated by visual analysi s of neuronal density. Our results show that a short episode of seizur e activity did not produce neuronal damage but almost completely prote cted vulnerable neurons from KA-induced neuronal damage. These results extend to epileptic tolerance the notion of tolerance previously desc ribed in the case of ischemia. (C) 1998 Elsevier Science B.V. All righ ts reserved.