Melatonin Negatively Regulates Fertility: A Study in Albino Rat (Rattus norvegicus)

This study was performed to evaluate the biological activity of melatonin on the fertility of male and female albino rat. The tested dose (1.0 mg/kg) of melatonin and reference drug "primovlar" were administered through oral route daily to female rats 2 cycles before mating (group I) and from the first day of mating till 21 days (group II). On the other hand, the male rats were administered only the tested dose of melatonin for two weeks before mating (group III). The effects of melatonin and primovlar administration on fertility index, pregnancy percentage, sperm count, hormonal levels (prolactin, FSH, LH, progesterone and estradiol) and some biochemical parameters (total lipid and cholesterol) were investigated. Also, histopathological changes of ovaries and testes of rats treated with melatonin were examined. The results showed significant decrease in the pregnancy percentage and fertility index and non-significant decrease in the sperm count after melatonin treatment. The data also showed significant increase in prolactin level and significant decrease of FSH, LH, estradiol and progesterone levels of male and female albino rats treated with melatonin or primovlar versus those of controls. In the same domain, biochemical analysis revealed significant elevation in total lipid and cholesterol levels. Histological examination showed little changes in ovarian and testicular structure in melatoninadministered animals versus those of controls.

In conclusion, the tested dose of melatonin affected the fertility in negative manner and exerted a more potent effect than primovlar.