The endocannabinoid system in bull sperm and bovine oviductal epithelium: role of anandamide in sperm–oviduct interaction

Abstract

Anandamide binds to cannabinoid receptors and plays several central and peripheral functions. The aim of this work was to study the possible role for this endocannabinoid in controlling sperm-oviduct interaction in mammals. We observed that bull sperm and bovine oviductal epithelial cells express cannabinoid receptors, CB1 and CB2, and fatty acid amide hydrolase, the enzyme that controls intracellular anandamide levels. A quantitative assay to determine whether anandamide was involved in bovine sperm-oviduct interaction was developed. R(C)-methanandamide, a non-hydrolysable anandamide analog, inhibited sperm binding to and induced sperm release from oviductal epithelia. Selective CB1 antagonists (SR141716A or AM251) completely blocked R(C)-methanandamide effects. However, SR144528, a selective CB2 antagonist, did not exert any effect, indicating that only CB1 was involved in R(C)-methanandamide effect. This effect was not caused by inhibition of the sperm progressive motility or by induction of the acrosome reaction. Overall, our findings indicate for the first time that the endocannabinoid system is present in bovine sperm and oviductal epithelium and that anandamide modulates the sperm-oviduct interaction, by inhibition of sperm binding and induction of sperm release from oviductal epithelial cells, probably by activating CB1 receptors.

Is there a role for endocannabinoids in sperm–oviduct interaction?

“…In the present paper, the presence of CB1 and CB2 in bovine spermatozoa has been demonstrated by both immunocytochemistry and western blot analysis, confirming a previous report by Gervasi et al (2009). The different localizations of receptors detected herein could be due to the use of different antibodies in the immunolocalization procedure.…”

“…An ECS has been demonstrated in human (Rossato et al 2005, Francavilla et al 2009), boar (Maccarrone et al 2005), mouse (Ricci et al 2007, Sun et al 2009), and bovine (Gervasi et al 2009). In mice, ECS modulates sperm motility during epididymal maturation, and high levels of endocannabinoids have been detected in mouse spermatozoa isolated from the caput of the epididymis, where they are functionally immotile, while low levels have been found in those isolated from the cauda where they acquire motility (Ricci et al 2007, Cobellis et al 2010.…”

“…Recently, Gervasi et al (2009) showed that nanomolar concentrations of AEA inhibited sperm-oviduct binding and induced sperm release in vitro. In the present study, AEA was tested at 2 nM and 5 mM (nZ4).…”

“…In human spermatozoa, the effect of AEA on the depression of motility has been demonstrated at both nanomolar (Aquila et al 2009) and micromolar concentrations (Rossato et al 2005), even though in the latter case the drop of motility was associated with a loss of sperm viability (Rossato et al 2005, Rossato 2008). In bovine spermatozoa, observational analysis demonstrated that AEA at nanomolar concentrations does not affect motility (Gervasi et al 2009). Herein, micromolar concentrations of AEA did not affect sperm viability but induced a rapid and persistent decrease in percent progressive motility and kinetic parameters.…”

“…in the spermreservoir, raises the hypothesis that endocannabinoids have a role during the sperm ascension along the oviduct. In this respect, AEA has been reported to inhibit in vitro sperm-oviduct binding, and promotes sperm release (Gervasi et al 2009). However, in the present study, we observed that AEA has no effects on sperm-oviduct binding and sperm release, even at a concentration of 5 mM.…”