Temporal profile of neuronal injury following pilocarpine or kainic acid-induced status epilepticus

Systemic administration of pilocarpine and kainic acid (KA) has been extens ively used to model temporal lobe epilepsy in rats. Here the regional distr ibution of selectively vulnerable neurons and the temporal evolution of suc h neuronal injury after status epilepticus (SE) are compared in both models . Using the silver staining technique of Gallyas, argyrophilic neurons were measured on a 0-3 (least-most) scale in 53 different brain areas. Few neur ons were silver-stained 2.5 h after kainate-induced SE, but many silver-sta ined cells could be seen in most neocortical, hippocampal, amygdaloid and h ypothalamic structures for pilocarpine group. In general, 8 or 24 h interva ls between SE onset and perfusion times yielded the most intense neuronal s ilver-impregnation. Pilocarpine-induced neuronal silver impregnation was mo re prominent than that induced by kainate treatment for many areas in corte x, hippocampus. endopiriform nucleus, amygdaloid complex and hypothalamus. On the other hand, in the thalamus, some cortical areas, claustrum, lateral septum and caudoputamen, kainate-induced neuronal silver staining was also prominent, but occurred later than in pilocarpine-treated animals. Neurona l injury was found in almost the same brain areas in both models of SE but with different intensity levels and time course profiles. It was suggested that such differences in the temporal profile of cell damage should be take n into account when searching for neuroprotective agents. (C) 2000 Elsevier Science B.V. All rights reserved.