Moclobemide-induced gynecomastia in rats

AIM: To study the toxic effect of moclobemide on male breast and to elucida te its mechanism of action. METHODS: Routine histopathological analysis was used to diagnose the effect of moclobemide on male breast in mts. Plasma c oncentrations of estrogen, androgen, and prolactin were measured by a ratio immunometer and relative receptors of mammary gland tissue were detected im munohistochemically. RESULTS: After 180-d moclobemide treatment, the presen ce of gynecomastia was 0, 5, 5, 7/10 rats in 0, 60, 240, and 600 mg/kg grou ps, respectively. After 30-d convalescence, only one rat in 600 mg/kg group got the incidence of gynecomastia. Serum prolactin concentration had a tre nd to decrease with increasing dose and prolactin receptors in mammary glan d were up-regulated. CONCLUSION: Long-term treatment with moclobemide cause s gynecomastia in rats, which is reversible. The mechanism of moclobemide-i nduced gynecomastia may be related to the increase in prolactin receptors i n mammary glands.