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

Systemic administration of pilocarpine and kainic acid (KA) has been extensively used to model temporal lobe epilepsy in rats. Here the regional distribution of selectively vulnerable neurons and the temporal evolution of such 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 neurons were silver-stained 2.5 h after kainate-induced SE, but many silver-stained cells could be seen in most neocortical, hippocampal, amygdaloid and hypothalamic structures for pilocarpine group. In general, 8 or 24 h intervals between SE onset and perfusion times yielded the most intense neuronal silver-impregnation. Pilocarpine-induced neuronal silver impregnation was more prominent than that induced by kainate treatment for many areas in cortex, 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. Neuronal 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 taken into account when searching for neuroprotective agents.