Evaluation of cannabinoid receptors Type 1 and Type 2 mRNA expression in mature versus immature spermatozoa from fertile and infertile males
In Summary: The endocannabinoid system (ECS) is a signalling system of the human body that comprises endogenous cannabinoids and their targets, cannabinoid receptors. Endogenous cannabinoids are lipid-derived signalling molecules produced by the human body. The main cannabinoid receptors come in two variants, CB1 – which is most highly expressed in the brain, and CB2 – which is most highly expressed in immune cells. These receptors alter the activities of various biological systems such as nervous system and immune system upon being activated by endogenous cannabinoids, as well as phytocannabinoids such as THC, the most known active constituent of cannabis, and other synthetic cannabinoids.
In the past decade, the significance of the ECS to the reproductive system has become more evident. In the male reproductive system in particular, cannabinoid receptors are demonstrated to be expressed in organs including the prostate gland and testicle, in male germ cells at different stages of differentiation, and in the hypothalamic region of the brain, which regulates production of reproductive hormones. Endocannabinoids are also found in the prostate gland, testicle, sperm, and their levels are correlated with the levels of hormones such as testosterone.
Most recently, scientists identified an association between the expression of cannabinoid receptors in sperm cells with sperm maturation. From a research study conducted on semen samples of fertile and infertile men, it was found that mature sperm cells always show significantly higher levels of CB1 and CB2 than immature sperm cells. However, the increment was markedly greater in the fertile group. Finally, in mature sperm cells, CB1 expression was related to variation in sperm morphology, and CB2 was related to both sperm morphology and motility.