Cannabis and Phencyclidine Self-Administration by Animals

Most studies of drug self-administration have concerned either opiate, depressant, or stimulant drugs (Schuster and Thompson, 1969). Few studies have involved hallucinogenic drug self-administration, primarily because of technical problems (e.g., long duration of action, lack of water solubility) associated with the use of these drugs. The present study investigates the intravenous self-administration of phencyclidine and Δ9-THC, and the self-administration by smoking of a natural cannabis substance (hashish). Phencyclidine is a synthetic anticholinergic drug with hallucinogenic properties (Brawley and Duffield, 1972). Cannabis compounds have been used by man for thousands of years primarily for their behavioral effects and contain Δ9-THC as the principal active ingredient (Mechoulam, 1970). Deneau and Kaymakcalan (1971) have reported intravenous self-administration of THC by monkeys, but only after physical dependence had been established to the drug. No report of phencyclidine self-administration by animals has been found.