Activation of pre- and postsynaptic protein kinase C during tetraethylammonium-induced long-term potentiation in the CA1 field of the hippocampus

Tetraethylammonium (TEA) induces a form of long-term potentiation (LTP) tha t is independent on N-methyl-D-aspartate (NMDA) receptor activation (LTPK). LTPK may be a suitable chemical model to study molecular mechanisms under lying LTP. We monitored the phosphorylation state of two identified neural- specific protein kinase C (PKC) substrates (the presynaptic protein GAP-43/ B-50 and postsynaptic protein RC3) after different chemical depolarisations , TEA induced a long-lasting increase in synaptic efficacy in the CA1 field of the hippocampus and increased the phosphorylation of both GAP-43/B-50 a nd RC3 (51 and 56.1%, respectively). These effects were blocked by the volt age-dependent calcium channel antagonist nifedipine, but not by the NMDA re ceptor antagonist AP5. These data show that in LTPK the in situ phosphoryla tion of pre-and postsynaptic PKC substrates is increased, indicating that N MDA receptor-dependent and NMDA receptor-independent LTP share common Ca2+- dependent expression mechanisms, including activation of pre- and postsynap tic PKC. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.