The gamma-aminobutyric acid system in rat cerebellum during cannabinoid-induced cataleptoid state.

Repeated, but not single, intraperitoneal injections of delta1,6-tetrahydrocannabinol (delta1,6-THC) 20 mg/kg to rats administered daily for two weeks, produced increased gamma-aminobutyric acid (GABA) concentration and decreased glutamic acid decarboxylase (GAD) activity in the cerebellum, as well as enhancement of [3H]-GABA uptake by cerebellar crude synaptosomes. It seems that the motor impairment elicited by delta1,6-THC was not associated with the GABA system, but presumably might be related to changes in brain excitability.