Possible involvement of protein kinase C (PKC) in the regulation of electrically evoked serotonin (5-HT) release from rabbit hippocampal slices

Protein kinase C (PKC)-activating phorbol esters enhanced the electrically evoked 5-HT release from rabbit hippocampal slices preincubated with [3H]5-HT. The release was diminished by polymyxin B, an inhibitor of PKC. These results are compatible with a stimulatory effect of PKC on the 5-HT release induced by action potentials. The mutual effects of PKC affecting drugs on 5-HT release suggest a functional but not a competitive interaction. The attenuation or the enhancement of effects of 5-HT autoreceptor ligands at various 5-HT biophase concentrations found after PKC-affecting drugs are in line with the view that autoreceptor-mediated events are not directly influenced by the enzyme PKC.