EFFECTS OF DELTA(9)-TETRAHYDROCANNABINOL ON COPULATORY-BEHAVIOR AND NEUROENDOCRINE RESPONSES OF MALE-RATS TO FEMALE CONSPECIFICS

Male rats exposed to sexually receptive females, exhibit a rapid incre ase in plasma levels of luteinizing hormone (LH) and prolactin, and co ncomitant increases in noradrenergic activity in the medial basal hypo thalamus (MBH) and median eminence (ME) as well as in dopaminergic act ivity in the MBH. Delta-9-tetrahydrocannabinol (THC; 5 mg/kg b.wt., PO ), the chief psychoactive constituent of marijuana, blocked the MBH an d ME noradrenergic response and the dopaminergic response in the MBH i n male rats exposed for 20 min to sexually receptive females, and supp ressed the expected increases in plasma LH and prolactin levels. Moreo ver, THC treatment decreased the percentage of animals exhibiting copu latory behavior and increased the latency periods to mount and intromi t. These findings indicate that THC interferes with the neuroendocrine and behavioral responses of male rats to the presence of a receptive female.