Synaptic transmission between cultured rat hippocampal neurons is enhanced by activation of protein kinase-C

Synaptic connections between rat hippocampal neurons were studied in dissociated cell culture. Activation of a cultured neuron by pulse application of glutamate could produce postsynaptic currents (PSCs) in other neurons in the culture dish. Activation of protein kinase C (PKC) by a phorbol ester caused an enhancement of the magnitude of the PSCs without affecting much the delay and decay time constant of the recorded PSCs. The increased reactivity to synaptic activation was not accompanied by a postsynaptic change in sensitivity to topical application of an excitatory amino acid, glutamate. A PKC inhibitor polymyxin B reduced the effects of the phorbol ester. It is suggested that PKC activation plays an important role in the regulation of release of neurotransmitters from cultured central neurons.