The endocannabinoid oleoylethanolamide increases human sperm motility

Abstract

Oleoylethanolamide (OEA) is a bioactive fatty acid amide present in human seminal plasma and is purported to modulate human sperm functions through its antioxidant and anti-inflammatory properties. The aim of this study was to determine the relationship between seminal plasma levels of OEA and sperm functions and the effects of in-vitro exposure of human sperm to physiological concentrations of OEA. Laboratory based clinical study. Seminal Fluid was obtained from 90 human donors with normal and abnormal semen parameters after 2-5 days of sexual abstinence. Seminal plasma lipids were extracted by a solid-phase method and OEA was quantified by UHPLC-ESI-MS/MS utilizing an isotope dilution method and selective ion monitoring. We evaluated in vitro, the effects of OEA on human sperm motility by incubation of highly motile sperm isolated by direct swim-up with different concentrations of OEA from 1nM to 1μM. The seminal plasma OEA concentration (mean ± SEM, nM) was significantly lower in men with asthenozoospermia (0.581 ± 0.106; P=0.01), oligoasthenoteratozoospermia (0.631 ± 0.078; P=0.0005) and azoospermia (0.298 ± 0.033; P=0.004) compared to normozoospermic levels (1.785 ± 0.284). After a 15–90 min incubation, OEA exerted a significant time-dependent increase on progressive motility (74, 76, 78, 78 and 78% vs 69, 68, 68, 67, and 65% of the control at the corresponding time). The effect of different concentrations of OEA from 10 nM to 1μM showed a significant dose-dependent increase in progressive sperm motility after 45 min incubation. Our results suggest that OEA plays an essential role in sperm functions by stimulating human sperm motility and that maintenance of OEA levels in human seminal plasma may be necessary for the preservation of normal sperm motility.