Effect of oxytocin on fertility of male rats

It is now recognised that oxytocin (OT) modulates several aspects of male reproduction. However, its overall impact on male fertility remains unknown. Thus, the aim of this study was to examine the effect of OT on male fertility. This was investigated in rats using three doses [0.1 International Units (IU) of OT once a day (n = 9), twice a . day and thrice a day, given intraperitoneally for 7 consecutive days] and a non competitive serial mating trial (on days 1,3 and 7 of treatment and day 7 posttreatment). The OT caused marked oligozoospermia without provoking toxic side effects (in terms of teratozoospermia, overt signs of toxicity, renotoxicity, hepatotoxicity or haemotoxicity) or compromising libido, mating performance and fertility (in terms of quantal pregnancy, number of uterine implants and indices of implantation and fertility). The oligozoospermia was mediated by retrograde ejaculation and by impairment of ejaculatory contraction of vas (as judged by inhibition of electrically elicited contraction of isolated vas) and probably epididymis. It is possible that OT analogues may be developed as post-testicular male contraceptives.