Abstract

SUMMARY: Since normal sperm parameters can be altered by organophosphorous pesticides, this study intended to determine if melatonin is able to prevent the damage on sperm quality after an acute exposure to diazinon. Adult male mice were injected intraperitoneally with melatonin, diazinon (1/3 or 2/3 LD50) or both, and sperm parameters were evaluated on days 1 or 32 post injection. Groups treated with diazinon showed elevated lipid peroxidation levels on day 1 post treatment, while groups pretreated with melatonin before diazinon showed no difference compared to control. Sperm count showed a significant decrease in both diazinon- treated groups only on day 32 post injection; no differences were observed in groups pretreated with melatonin prior to diazinon compared to control. The percentage of abnormal sperm morphology increased in the diazinon-treated groups only on day 32 postinjection. The administration of melatonin prior to exposure to diazinon prevents the alteration of sperm parameters commonly caused by organophosphates, possibly due to its antioxidant properties.