EFFECTS OF ANANDAMIDE (ENDOGEN CANNABINOID) ON ANTERIOR-PITUITARY HORMONE-SECRETION IN ADULT OVARIECTOMIZED RATS

It has been shown that the main psychoactive component of marihuana, D elta(9)-tetrahydrocannabinol (THC) has mainly inhibitory effects on pi tuitary luteinizing hormone (LH), prolactin (PRL) and growth hormone ( GH) and has no or little effect on follicle stimulating hormone (FSH) secretion. Recently the purification and availability of the putative endogenous ligand for the cannabinoid receptor, anandamide (arachidony l ethanol-amide, anandamide) (ANA) provided us the opportunity to comp are the effects of THC and ANA. on the female neuroendocrine system in ovariectomized (OVX) rats. OVX was performed three weeks prior to the experimental period to avoid cyclic differences. OVX rats were inject ed i.p. with either THC or ANA (0.02mg/kg.b.w./day, respectively) or v ehicle for two weeks. The results show that both ANA and THC decrease serum LH level although THC with a higher degree, No significant diffe rences were observed in serum FSH level. Both drugs decreased serum PR L. Serum GH was increased after THC administration and significantly d ecreased after ANA. The results indicate that ANA and THC alter pituit ary hormone secretion, mainly by inhibitory action. The site of action requires further investigations.