The extracellular signal-regulated kinase cascade is required for NMDA receptor-independent LTP in area CA1 but not area CA3 of the hippocampus.
We have examined the requirement for protein kinase activity in long-term potentiation (LTP) induced by activation of voltage-dependent Ca2+ channels (VDCCs) in hippocampal slices. We previously demonstrated that LTP induced by application of the K+ channel blocker tetraethylammonium (TEA-LTP) consisted of two distinct components, an NMDA receptor-dependent component and a VDCC-dependent component. The results herein demonstrate that both the NMDA and VDCC-dependent components of TEA-LTP are blocked by K-252a, a broad spectrum protein kinase inhibitor. Furthermore, VDCC-dependent TEA-LTP is attenuated by KN-62, a specific inhibitor of Ca2+/calmodulin dependent protein kinase II (CaM-KII). These results demonstrate that LTP induced by VDCC activation requires protein kinase activity and suggest that different routes of postsynaptic Ca2+ influx activate protein kinases to trigger the induction of LTP but that these enzyme systems may be contained in different cell compartments.