delta-9-tetrahydrocannabinol (THC) increases brain prostaglandins in the rat

Intraperitoneal administration of 9-trans-delta-tetrahydrocannabinol (THC), the major psychoactive component of cannabis, in doses of 0.5, 1.0 and 2.0 mg/kg, produced a dose-related increase in the brain concentrations of prostaglandin (PG) E2 and PGF2 alpha in male rats 4 h after THC administration, as assessed by radioimmunoassay. A time-course investigation indicated that THC (2 mg/kg, IP) induced maximal increases in rat brain concentration of both PGs 2 and 4 h after administration; PG levels declined appreciably by 8 h and were normal by 24 h. A time-course study on the hexobarbitone (100 mg/kg, IP)-induced hypnosis potentiating effect of THC (2.0 mg/kg, IP) in male rats revealed that this pharmacological action of the cannabinoid correlated well with the time-course of the THC-induced increase in rat brain PG concentrations. The present study lends support to earlier reports contending that PGs may mediate some of the central actions of THC.