Effects of cannabis resin on learning by repetition in the rat.

Studies were made of the effects of cannabis resin in differing doses on a type of learning by repetition, using the water-filled maze technique, and on the conditioned avoidance reflex in the rat. When administered at a dose corresponding to 0.5 mg of delta9-THC per kg, the resin led to improved learning in both the types of test employed; opposite effects were observed with the higher dose (corresponding to 5 mg of delta9-THC per kg). These effects are probably attributable to complex reciprocal action between the active constituents of the resin, particularly THC, and the metabolisms of the cerebral monoamines and c-AMP.