Anandamide exerts a suppressive effect on sperm binding to oviduct explants through CB1 receptors in the water buffalo (Bubalus bubalis)

•The effect of Anandamide (AEA) and its receptor antagonist on sperm-oviduct binding was studied in the water buffalo.•AEA significantly decreased the number of sperm bound to the oviduct explant at 1 nM concentration.•At 1 micromolar concentration AEA did not affect the number of sperm bound to the oviduct explant.•The effect of AEA on sperm-oviduct binding was mediated through CB1 receptor.•CB1 antagonist (SR141716A) reversed the inhibitory effect of AEA on sperm oviduct binding.

An endocannabinoid system comprising of Anandamide (AEA) and its receptor has been shown to play a role in sperm acquisition of fertilizing potential and sperm-oviduct interaction. In the present study, we assessed the effect of sperm pre-treatment with AEA or co-incubation of sperm-oviduct explants with AEA in the presence or absence of CB1 receptor antagonist (SR141716A) on sperm-oviduct binding in the water buffalo. Cryopreserved spermatozoa from 3 Murrah buffalo bulls (3 ejaculates from each bull) were utilized for the study. Oviduct explants were prepared by overnight culture of epithelial cells in TCM- 199 and washed spermatozoa were added to the oviduct explants and incubated for 1 h. Then, sperm-oviduct explants were stained with a fluorescent stain (JC-1) and sperm binding index (BI - No. of bound spermatozoa/unit area of oviduct explants) was assessed. The results indicate that BI decreased significantly (P < 0.05) when spermatozoa were either pre-treated with AEA (14.16 ± 0.87) or sperm-oviduct explants were co-incubated with AEA (16.27 ± 0.86) at 1 nM concentration compared to the control group (29.12 ± 2.17), however such effect was not observed when AEA was used at 1 μM concentration. Incorporation of SR141716A in the incubation medium inhibited the suppressive effect of AEA on BI. It was concluded that AEA, at 1 nM concentration, decreased the number of spermatozoa bound to the oviduct explants and the suppressive effect of AEA on sperm-oviduct binding was inhibited by CB1 receptor antagonist suggesting that the effect of AEA was mediated through CB1 receptor in the water buffalo.