Effects of Δ 9-tetrahydrocannabinol on the levels of cyclic adenosine 3',5'-monophosphate in mouse brain

The effects of intraperitoneal injections of various doses of Δ 9-tetrahydrocannabinol ( Δ 9-THC) on brain levels of cyclic adenosine 3',5'-monophosphate (cyclic AMP) have been studied in mice. Doses of Δ 9-THC in the range of 0.1 to 1.0 mg/kg cause a 50–160 per cent elevation of cyclic AMP levels compared to controls (P < 0.0005), while doses of Δ 9-THC in the range of 2.0 to 10.0 mg/kg cause a 30–60 per cent depression of cyclic AMP levels (P = 0.025 to 0.0005). This pattern was obtained in whole brain, as well as in dissected samples of cortex, cerebellum and medulla. This over-all biphasic effect of THC on cyclic AMP levels correlates with known changes in biogenic amines, temperature regulation, and behavior caused by this drug.