Dopamine has been found in both semen and oviductal fluid and dopamine receptors (DRs) have been detected in male genital tract and spermatozoa, suggesting that dopamine system may control important reproductive functions in humans. Dopamine improves sperm motility and viability in animal models, although the underlying molecular mechanisms have not been fully elucidated. The aims of this study were to investigate DRs expression in human spermatozoa and to evaluate the in vitro effects of DRs agonists and antagonists on human sperm motility, kinetics and viability. DRs expression was assessed by immunofluorescence and western blot in spermatozoa from healthy volunteers and the effects of D2DR-like agonist cabergoline, D2DR-selective antagonist L-sulpiride, D4DR-selective agonist PD168,077 and D4DR-selective antagonist U-101958 on sperm motility, kinetics and viability were tested after 1 hour of treatment with serial doses of compounds. Sperm motility and kinetics were analyzed by Sperm Class Analyzer [SCA] 5.0, sperm viability was assessed by Vital Stain Dye. D2DR and D4DR are both expressed in human spermatozoa. Cabergoline significantly increased rapid progressive motile spermatozoa (RPMS) and decreased non motile spermatozoa (NMS). L-sulpiride showed opposite, although not significant, effects on sperm motility. PD168,077 and U-101958 did not significantly change sperm motility. Moreover, L-sulpiride significantly decreased curvilinear velocity (VCL) and increased wobble (WOB). All tested compounds did not affect sperm viability. Both cabergoline and PD168,077 induced Akt phosphorylation, compared to untreated spermatozoa. The results of the current study demonstrated that dopamine pathway may be involved in the modulation of human sperm motility and kinetic parameters, without affecting sperm viability, and that Akt could be regarded as a putative mediator; however, further experiments are being performed to identify the molecular mechanisms driving these effects.
28 - 31 May 2016
European Society of Endocrinology