Melatonin and aromatase stimulating activity of human seminal plasma

Melatonin concentrations and aromatase stimulating activity were determined in human seminal plasma and correlated with sperm density and motility. Aromatase stimulating activity was determined with an in vitro rat granulosa cell system and melatonin by radioimmunoassay. Compared to normal semen, aromatase stimulating activity was lower in azoospermic individuals, while melatonin was higher in oligospermic and azoospermic samples. Aromatase stimulating activity correlated positively with sperm concentrations and a negative correlation was found between melatonin and sperm progression. These findings suggest that low sperm production is associated with low aromatase stimulating bioactivity in seminal plasma; and melatonin may have an effect upon both sperm production and motility.