EFFECT OF SEIZURE ACTIVITY AND CALPAIN INHIBITOR-I ON LTP IN JUVENILE HIPPOCAMPAL SLICES

Kainic acid-induced seizure activity in adult rats produces an impairment of long-term potentiation induction in hippocampal slices. As the consequences of seizure activity are different in adult and juvenile rats, we tested the ability of hippocampal slices prepared from kainate-treated juvenile rats to exhibit long-term potentiation. Long-term potentiation was induced by theta-burst stimulation and was not significantly different in slices prepared from control or kainate-injected juvenile rats (16-18 postnatal days). Short-term potentiation, however, was reduced in the kainate-treated juveniles. Calpain inhibitor I has been shown to prevent long-term potentiation formation in adult hippocampal slices, and we evaluated its effect on long-term potentiation in hippocampal slices from juvenile rats. Calpain inhibitor I produced a significant reduction in the degree of long-term potentiation induced by theta-burst stimulation in hippocampal slices prepared from 14-20 postnatal day-old animals. The results are consistent with the notion that, although similar mechanisms participate in the formation of long-term potentiation in juvenile and adult animals, juvenile animals are much more resistant than adult animals to the consequences of seizure activity.