ABSTRACT
Cannabinoid exerts its effects via interactions with two types of cannabinoid receptors, braintype receptor (CB1) and spleen-type receptor (CB2). While both receptors are expressed in preimplantation mouse embryos, our findings suggest that the effects of cannabinoids on embryo development and implantation are primarily mediated by CB1. The levels of CB1 in mouse blastocyst are much higher than in the brain. Furthermore, the mouse uterus has anandamide synthesizing and hydrolyzing capacities that are differentially regulated during the periimplantation period. The uterus also contains high levels of endogenous cannabinoid, anandamide. Natural, synthetic and endogenous cannabinoid ligands interfere with preimplantation embryo development and blastocyst implantation, and these effects are completely reversed by specific CB1 antagonists. These results suggest that preimplantation mouse embryos are possible targets for cannabinoid ligand-receptor signaling during early pregnancy in the mouse.
