Selective potentiation of N-methyl-D-aspartate-induced current by protein kinase C in Xenopus oocytes injected with rat brain RNA

Glutamate receptors and protein kinase C (PKC) may play significant roles in long-term potentiation in hippocampus. To clarify the regulatory involvement of PKC in the functions of glutamate receptors, we examined the effects of PKC activation on current response induced by the activation of each subtype of glutamate receptor in Xenopus oocytes injected with rat brain RNA. Treatment with the PKC activator, 12-O-tetradecanoylphorbol-13-acetate (TPA), potentiated N-methyl-D-aspartate (NMDA)-induced current by about 2.5-fold, although it did not affect kainate-induced current at all. Quisqualate-mediated oscillatory current was almost abolished by this treatment. The TPA-induced potentiation of NMDA current was suppressed by staurosporine, an inhibitor of protein kinases. Pretreatment with 4-O-methyl-TPA, an inactive phorbol ester, had no effect on NMDA current. Current response mediated by NMDA receptors would thus appear to be modulated by PKC.