| The effect of cannabinoids on oocyte and sperm competence
Cannabis (marijuana) has been used for many years for both therapeutic and recreational purposes. The discovery of the Cannabis components and their classification as cannabinoids as well as the endocannabinoid system lead to an intense research. The main component, Δ9-tetrahydrocannabinol (Δ9-THC), found as the psychoactive compound, while other cannabinoids, mainly cannabidiol (CBD) does not have any psychoactive effects. Cannabis plants contain varying amounts of Δ9-THC and CBD, depending on the strain, and they can therefore be used for different purposes. A relatively higher percentage of CBD with a maximum 3% Δ9-THC refers to low-potency marijuana and usually entails medical benefits. In contrast, a higher percentage (>9%) of Δ9-THC refers to high-potency marijuana that is usually used for recreational purposes. Δ9-THC binds to cannabinoid receptors (CB1R and CB2R), and plays a dual role by either block or activates the receptors, depending on their density and coupling efficiencies. In contrast, CBD has low-affinity binding and can acts as a Δ9-THC antagonist. CB1 receptors are mainly expressed in the brain, but also in the peripheral tissues. CB2 receptors are mostly expressed in immune cells, but are also found in the female and male reproductive tissues. Localization of CB receptors in the ovary and testis suggesting that reproductive tissues are a target for exogenous cannabinoids. Females seem to be more sensitive to high-potency marijuana then males, as reflected in behavioral and physiological effects. Consumption of high-potency marijuana affects women's menstrual cycle and ovulation, in amount- and use-dependent manners.
Given the current trend of legalizing of Cannabis use and its increased use as a therapeutic drug, the impact on female fertility should be examined more closely. Data are limited to epidemiological and retrospective research, and there is a lack of knowledge about the specific effect of cannabinoids on the ovarian pool of oocytes and the developing embryo. Our main goal is to better understand the effect of different cannabinoids on oocyte maturation mechanism as well as on sperm quality, fertilization competence and further embryonic development along with the quality evaluation of the developed embryo.