ACTIVATION OF THE CANNABINOID RECEPTOR BY DELTA(9)-TETRAHYDROCANNABINOL REDUCES GAMMA-AMINOBUTYRIC-ACID UPTAKE IN THE GLOBUS-PALLIDUS

The interaction between GABA (gamma-aminobutyric acid) and cannabinoid s in the globus pallidus was investigated by evaluating the effects of Delta(9)-tetrahydrocannabinol on [H-3]GABA uptake into slices of rat globus pallidus. Delta(9)-Tetrahydrocannabinol caused a concentration- dependent decrease in GABA uptake (51% decrease at 100 mu M Delta(9)-t etrahydrocannabinol, IC50=18.95 mu M). This effect was reversed in a c oncentration-dependent manner (IC50=11.9 mu M) by the cannabinoid rece ptor antagonist SR 141716A )-4-methyl-1H-pyrazole-3-arboxiamidehydroch loride. SR 141716A alone did not affect GABA uptake. These results sho w that cannabinoid receptor activation reduces GABA uptake in the glob us pallidus.