A comparison of the roles of protein kinase C in long-term potentiation in rat hippocampal areas CA1 and CA3.

1. Using agonists and antagonists with specificity toward various isozymes, we have examined the role of protein kinase C (PKC) in long-term potentiation (LTP) in rat hippocampal areas CA1 and CA3. 2. Agonists (indolactum V but not phorbol ester) and antagonists (sphingosine, staurosporine, chelerytherene) acting at all PKC isozymes reduce or block LTP induction at both sites. 3. However ingenol, a relatively specific agonist at the delta and epsilon isozymes, blocks LTP in the MF-CA3 pathway, but not in the SC-CA1 pathway. 4. Go6976, a relatively specific antagonist of the alpha and beta isozymes, blocks LTP in the SC-CA1 pathway at both ages tested (30- and 60-day-old animals), but blocks LTP in the MF-CA3 in 60 but not 30-day-old animals. 5. Our studies indicate that different PKC isozymes are crucial to LTP induction in these two areas of hippocampus, and that there are development changes in the profile of isozymes.