delta 9-Tetrahydrocannabinol and anandamide enhance the ability of muscimol to induce catalepsy in the globus pallidus of rats.

Doses of 3 or 30 micrograms of delta 9-tetrahydrocannabinol markedly increased the ability of 25 ng of muscimol to delay the descent of rats from a horizontal bar (descent latency) when these drugs were coadministered bilaterally into the globus pallidus. Intrapallidal injections of 30 micrograms of the putative endogenous cannabinoid, anandamide, also increased the effect of muscimol on descent latency. These data indicate that the production of catalepsy by cannabinoids may depend at least in part on an ability to enhance GABAergic transmission in the globus pallidus and support the hypothesis that anandamide is indeed an endogenous ligand for the cannabinoid receptor.