Effect of prenatal melatonin exposure on gonadotropins and prolactin secretion in male and female rat pups

We evaluated whether melatonin administration to pregnant rats during the f inal week of pregnancy affects prepubertal secretion of luteinizing hormone (LH), follicle stimulating hormone (FSH), and prolactin in offspring. Mela tonin was administered in the drinking water from day 14 to delivery. LH, F SH and prolactin concentrations were determined in plasma sampled from offs pring between 5 and 30 days in the dark portion of the diurnal cycle. Admin istration of 2 or 20 mug/ml melatonin did not affect LH or FSH in male or f emale offspring. The 20-mug/ml dose caused a significant increase in prolac tin. in males and females at day 15. In contrast, melatonin, 2 or 20 mug/ml , decreased prolactin at days 25 and 30 in females and day 25 in males. Thu s, prenatal melatonin exposure alters prolactin secretion, but not that of LH and FSH in infantile and prepubertal male and female rats. (C) 2001 Publ ished by Elsevier Science B.V.