Increased enkephalin gene expression in the hippocampus following seizures

Bilateral, recurrent seizures were induced in adult male rats by a unilateral, electrolytic lesion of the dentate gyrus hilus. This treatment led to a bilateral depletion of enkephalin-like immunoreactivity in the hippocampal mossy fibers by 12 hours (h) post-lesion, a rebound above normal levels by 24 h, a further rise by 4 days than a fall to control values by 10 days post-lesion. The mRNA for preproenkephalin was elevated in the granule cells by 3h post-lesion, reached a maximal 24-fold rise by 30 h then fell again to control values by 4-10 days post-lesion.