CEFYBO   02669
CENTRO DE ESTUDIOS FARMACOLOGICOS Y BOTANICOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
The endocannabinoid anandamide (AEA) regulates the oviductal sperm selection in bovines by inducing sperm capacitation
Autor/es:
GERVASI MARÍA GRACIA, OSYCKA-SALUT CLAUDIA, BURDET JULIANA, FRANCHI ANA MARÍA AND PEREZ MARTINEZ SILVINA
Lugar:
Holderness
Reunión:
Simposio; Gordon Research Conferences, Fertilization and Activation of Development; 2013
Resumen:
Mammalian oviduct acts as a reservoir for spermatozoa and provides an environment in which they may compete to fertilize an oocyte. Sperm-oviduct interaction is essential for sperm capacitation, and is a tightly regulated process influenced by the local microenvironment. Endocannabinoids are lipid mediators involved in many reproductive functions. Previously, we reported that the endocannabinoid AEA promotes sperm release from bovine oviductal epithelial cells by activating cannabinoid receptors (CB1) and vanilloid receptors (TRPV1). The aim of this work was to study the regulation and the mechanism of action of AEA in the oviductal selection of spermatozoa. We characterize the main metabolic pathway of AEA through the estrous cycle in the bovine oviduct. The expression and localization of FAAH (enzyme that degrades AEA) and NAPE-PLD (enzyme that synthesize AEA) protein in the oviduct did not change between the different stages of the estrous cycle. However the AEA concentrations from the oviductal fluid fluctuate between nanomolar levels, and the highest intracellular levels of this endocannabinoid were found in the post-ovulatory stage (p<0,05). This suggests that ovarian hormones may be regulating the oviductal AEA metabolic pathway. Then we studied the possible modulation by ovarian hormones of the AEA-induced sperm release. Using in vitro co-cultures of oviductal epithelial cells with spermatozoa, we found that estradiol and progesterone promote sperm release from bovine oviductal epithelial cells at 2 and 4 h incubation (p<0,05). Interestingly, only estradiol promotes sperm release by activating a pathway that involves CB1 and TRPV1 receptors (p<0,05). Taking together, our results indicate that estradiol may regulate oviductal AEA levels that are involved in the regulation of sperm release from the oviductal reservoir. Finally, we studied the molecular way of AEA in sperm selection by the oviductal epithelium in bovines. Due to sperm capacitation is one of the proposed causes of sperm release from the oviduct, we analyzed if AEA is involved in this process. Our results indicated that AEA (1 nM) induces events related to sperm capacitation by the activation of the CB1 and TRPV1 receptors (p<0,05). As indicative of sperm capacitation, we also measured Ca2+i in spermatozoa co-cultured with oviductal epithelial cells. The proportion of spermatozoa that increased Ca2+i was similar in all treatments (~40%). However, the Ca2+i levels were higher in spermatozoa incubated with AEA (1 nM), capsaicin (selective agonist of TRPV1; 0,1 µM) or URB597 (FAAH inhibitor, 5 nM) as compared with control (p<0,05). This increase was reversed by the incubation with CB1 and TRPV1 selective antagonists. Taking into account our results, we propose that in the peri-ovulatory moment, stimuli such as ovarian hormones could induce an increase of oviductal AEA levels. And this endocannabinoid regulates the oviductal sperm selection by inducing an increase in sperm Ca2+i levels and sperm capacitation with the consequent sperm release from the oviductal reservoir.