The effects of cannabinoids on the regulation of reproduction

It has been shown that the main psychoactive component of marihuana, Delta( 9)- tetrahydrocannabinol (THC) has mainly inhibitory effects on the regulat ion of reproduction. Recently, the purification and availability of the end ogenous ligand of the cannabinoid receptor, arachidonyl ethanolamide, anand amide, (ANA) and its specific long lasting antagonist, the SR 141716 (SR) p rovided us the opportunity to compare the effects of THC and ANA on the neu roendocrine regulation of reproduction. ANA decreases serum luteinizing hor mone (LH) and prolactin (PRL) levels in rats of both sexes. It has no actio n on serum follicle stimulating hormone (FSH) level. When ANA was administe red to pregnant rats it resulted in an increase of the duration of pregnanc y and in the frequency of stillbirths. The postnatal development of hypotha lamo-pituitary axis in offspring was temporarily inhibited. In conclusion, we found that exogenous and endogenous cannabinoids have only slightly diff erent effects on the reproductive parameters. These effects may occur via t he central cannabinoid receptor. It is possible that the sites of action ar e at both hypothalamic and pituitary levels. The results further support th e view that ANA may be a central neurotransmitter or neuromodulator.