CONICET | Buscador de Institutos y Recursos Humanos

The endocannabinoid system (ECS) is an evolutionarily conserved system and has been detected in most reproductive tissues and fluids. ECS is composed of the metabolizing enzymes, the cannabinoid (CBs and TRPVs) receptors and the endocannabinoids. Anandamide (AEA) is the major endocannabinoid and plays a crucial role in sperm function. In addition, AEA is present in uterine and oviductal fluids, and in this sense, spermatozoa are exposed to AEA when they swim through the female´s reproductive tract which might affect their sperm fertilizing ability. Previously, we found in bovines that AEA is involved in sperm capacitation by activation of CB1 and TRPV1, but not CB2 receptors. Furthermore, we recently characterized in bull spermatozoa a novel cannabinoid receptor, G protein-coupled receptor 55 (GPR55), which is also modulated by AEA. The weight of evidence points to GPR55 as a receptor that is activated by certain cannabinoid ligands, such as AEA, and by the bioactive lipid l-α-lysophosphatidylinsoitol (LPI). GPR55 is coupled to different G proteins that activate a widespread of signaling cascades that include cAMP/PKA and PLC/PKC pathways. We demonstrated that GPR55 is localized in the equatorial segment and in the flagellum of capacitated spermatozoa. Also, the activation of GPR55 by AEA is involved in the regulation of sperm motility in bull spermatozoa. In this work, we aimed to study the possible molecular pathways triggered by the activation of GPR55 involved in the regulation of sperm motility. First, we confirmed the participation of GPR55 in sperm motility by using different pharmacological tools. Results of computer-assisted sperm analysis supported that the increase of progressive motility by AEA 1 nM and Met-AEA 1.4 nM (a non-hydrolysable analogue of AEA) was reverted by 10 μM CID16020046, a selective GPR55 antagonist (p