Effect of melatonin on reproductive system in male rat, treated with estrogen in the first day of life.

The study aimed at demonstrating the possible stimulating or inhibitory effect of melatonin on reproductive system of male rats, the function of which was altered by single diethylstilbestrol dose introduced in the first day of life. The single estrogen dose in the first day of life induced in the studied rats, after they reached the adult age, inhibition of spermatogenesis as well as morphological and functional alterations in accessory sexual glands. This was associated with high level of LH gonadotrophin and with lowered testosterone level in the serum. Additional administration of melatonin between 45th and 84th day of life accentuated the above described changes induced by the single estrogen injection. Results of the studies demonstrated that melatonin in the experimental model not only failed to stimulate but provided an additional inhibitory effect on reproductive system in male rat.