Moclobemide-induced gynecomastia in rats.

AIM: To study the toxic effect of moclobemide on male breast and to elucidate its mechanism of action.

METHODS

Routine histopathological analysis was used to diagnose the effect of moclobemide on male breast in rats. Plasma concentrations of estrogen, androgen, and prolactin were measured by a ratioimmunometer and relative receptors of mammary gland tissue were detected immunohistochemically.

RESULTS

After 180-d moclobemide treatment, the presence of gynecomastia was 0, 5, 5, 7/10 rats in 0, 60, 240, and 600 mg/kg groups, respectively. After 30-d convalescence, only one rat in 600 mg/kg group got the incidence of gynecomastia. Serum prolactin concentration had a trend to decrease with increasing dose and prolactin receptors in mammary gland were up-regulated.

CONCLUSION

Long-term treatment with moclobemide causes gynecomastia in rats, which is reversible. The mechanism of moclobemide-induced gynecomastia may be related to the increase in prolactin receptors in mammary glands.