Effects of Pubertal Treatment with Bisphenol A and Bis-GMA on Sex Hormone Level in Male Rats

摘要

Environmental estrogens (xenoestrogens) are a diverse group of chemicals that mimic estrogenic actions. In the present study, we reported the in vivo evaluation of the effects of the environmental estrogenic chemicals, 2,2-bis-(4-hydroxyphenyl)-propane (bisphenol A, BPA) and 2,2-bis[4'-(2-hydroxy-3'-methacryloxyl) phenyl] propane (Bis-GMA) on the levels of testosterone (T) and estradiol-17beta (E_2) in plasma of pubertal male rats. The chemicals, BPA (5 mug or 5 mg/day), Bis-GMA (5 mug or 5 mg/day), E_2 (5 mug/day), and diethylstilbestrol (DES, 5 mug/day) were injected subcutaneously into male rats every two days from 3 to 11 weeks of age. The rats were sacrificed at 13 weeks of age and their plasma T and E_2 levels were analyzed. Neither BPA nor Bis-GMA injections changed the body weight, while E_2 and DES reduced the gain in body weight. E_2, DES and low-dose (5 mug) Bis-GMA reduced the testis weight. Although the T levels in plasma were not affected by high-dose treatments (5 mg) with BPA and Bis-GMA, treatment with E_2, DES and low-dose BPA and Bis-GMA reduced the T levels. Significant increases in plasma E_2 levels were observed in animals treated with E_2, DES and high-dose BPA compared with those treated with the vehicle control. Bis-GMA and BPA at a low dose had no effects on the E_2 level in plasma. BPA and Bis-GMA were found to distrubed the sex hormone production in male rats during puberty. BPA and Bis-GMA have similar potency in reducing T production, while BPA was found to more activity increase the plasma E_2 level than Bis-GMA. We postulate that chemicals at low doses exhibit multiple endocrine activities via complex mechanisms.