ACTA ENDOCRINOLOGICA (BUC)

Introduction. Antigonadotropic effect of melatonin in seasonally breeding rodents is due to the influence of this indol on the reproductive axis hypothalamicpituitary-gonads, although it is known that melatonin has a negative effect on the hormonal function of the reproductive axis, and is unknown whether it can affect the fertility of male Wistar rats.\r\nAim. The objective of this study was to investigate the effects of melatonin application on the fertility of the male Wistar rat.\r\nMaterials and Methods. Sixteen male Wistar rats were used. Rats were divided into two groups, Control and the group of animals treated with melatonin 1mg/kg (M) injected i.p. daily for two months. The evaluation of fertility was\r\ndetermined by the number of pregnant female rats. In addition, it was quantified the number of spermatozoa and Leydig cells in the seminiferous tubules. After removing\r\nthe treatment for two months, the experiments were repeated, to determine the possible recovery.\r\nResults. The results showed that rats treated with melatonin were able to impregnate only 25% of the mated female rats\r\n(p<0.05). In this group, the number of sperm decreased with a significance of p< 0.001 while the number of Leydig cells increased with respect to the control group with a significance of p< 0.001. After removing the treatment for two months, both the sperm and the Leydig cells were recovered at similar levels as the control group, while the fertility was not totally recovered in the group treated\r\nwith melatonin. These results suggest that the exogenous melatonin application (1mg/kg i.p) induces infertility.