INFLUENCE OF SECURININE ON 5 KINDS OF NEUROTRANSMITTER RECEPTORS AND MEMBRANE POTENTIAL OF FROG SPINAL CORD

Using radioligand binding assay method, securinine was shown to be specifically bound to GABA receptors of rat brain with IC₅₀ of 10^(-4)～10^-5mol/L. However, securinine did not exhibit affinity for a₁-, a₂- adrenoceptors and M-cholinergic receptors of rat brain and the β-adrenoceptors of duck erythrocyte membrane. In isolated and perfused bullfrog spinal cord experiment, the depolarization induced by GABA was slightly depressed by securinine (1 mmol/L), but no antagonistic effect on glycine or taurine evoked depolarization was observed with securinine. These results indicate that securinine is a weak GABA antagonist.