DELTA-9-TETRAHYDROCANNABINOL INHIBITS PULSATILE LUTEINIZING-HORMONE SECRETION IN THE MALE-RAT - EFFECT OF INTRACEREBROVENTRICULAR NOREPINEPHRINE INFUSION

An inhibitory dose of delta-9-tetrahydrocannabinol (THC) reduced plasm a LH levels by 50% and abolished the pulsatile pattern of LH release i n castrate, testosterone-treated rats. Norepinephrine (NE) was infused into the third ventricle of the brain in vehicle and THC-treated rats and the effects on LH release were examined. Although the lower dose of NE (10 mu g) did not alter plasma LH levels, the 100 mu g dose of N E induced a significant increase in LH in both vehicle and THC-treated animals. Pretreatment with the NE receptor antagonist phenoxybenzamin e prevented the NE-induced increase in plasma LH concentrations. Thus, THC does not block the stimulatory effect of NE on LH secretion in vi vo which suggests that other CNS mechanisms may be involved in the abi lity of THC to inhibit LH secretion.