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.
R(+)-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(+)-methanandamide effects.However, SR144528, a selective CB2 antagonist, did not exert any effect, indicating that only CB1 was involved in R(+)-methanandamide effect.This effect was not caused by inhibition of the sperm progressive motility or by induction of the acrosome reaction.(2007) found that annexins (that contain fucose residues) might be possible candidates for sperm receptors on bovine oviductal epithelium.
Besides, it is known that sulfated glycoconjugates are powerful inducers of sperm release .
1994), suggesting a critical role for this lipid during cell signaling (Schuel 2006).
CB-R are widely distributed in neuronal cells and in somatic cells from peripheral organs including the reproductive system (Paria . Recently, it has been reported that human and boar sperm express CB1 and that CB1 activation modulates motility, capacitation, and acrosome reaction, events that take place in the oviduct (Maccarrone .
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.
The mammalian oviduct acts as a functional sperm reservoir providing a suitable environment that allows the maintenance of sperm fertilization competence until ovulation takes place (Harper 1994).
After mating, mammalian spermatozoa (SPZ) are sequestered in the lower oviduct through adhesion to the epithelial cells lining its lumen (Smith & Yanagimachi 1990).