GABA P(1) RECEPTOR - INHIBITION BY PROTEIN-KINASE-C ACTIVATORS

The effects of protein kinase C (PKC) activators on gamma-aminobutyric acid (GABA) rho(1) receptor function were studied in rho(1)-expressin g Xenopus oocytes. The PKC activator phorbol 12-myristate 13-acetate ( PMA) but not the inactive analog phorbol 12-mono-myristate inhibited t he GABA-gated chloride currents. Mezerein, a non-phorbol ester type PK C activator, also inhibited the rho(1) responses, but 8-chlorophenylth io-cyclic AMP, a protein kinase A activator, had no effect. The effect of PMA was significantly reduced by a PKC inhibitor, staurosporine. T hese results suggest that GABA rho(1) receptor function can be regulat ed by PKC-mediated phosphorylation events.