Inhibition by some phenolic antioxidants of Ca2+ uptake and neurotransmitter release from brain synaptosomes

We present observations on the action of the phenolic antioxidants 2,3-tert-butyl-4-methoxyphenol (BHT); 2,6-di-tert-butyl-4-methylphenol (BHA); n-propyl-gallate and nordihydroguaiaretic acid (NDGA) on the function of guinea pig cerebral cortex synaptosomes. While the Ca2+ uptake observed under non depolarizing conditions is not affected by these agents, the depolarization induced Ca2+ uptake is strongly inhibited. Similarly the phenolic antioxidants studied inhibit the Ca2+ plus depolarization induced exocytosis of GABA and glutamate. These results which are similar to those previously obtained in blood platelets (Alexandre, A. et. al. Biochem. Biophys. Res. Comm. 139, 509-514, 1986), may indicate that free radical intermediates are involved in stimulus-secretion coupling.