Differential expression of 3 beta -hydroxysteroid dehydrogenase mRNA in rat testes exposed to endocrine disruptors.

摘要

Expression of 3 beta -hydroxysteroid dehydrogenase (3 beta -HSD) is mainly found in the Leydig cells from which steroid hormones are biosynthesized in the testes. To investigate whether endocrine disruptors affect the microenvironment of the testes, the mRNA expression of 3 beta -HSD as a molecular marker for androgen biosynthesis was analysed in rat testes exposed to several endocrine disruptors using a reverse transcription-polymerase chain reaction technique. Testosterone [50, 200 and 1000 micro g/kg body weight (BW)], flutamide (1, 5 and 25 mg/kg BW), ketoconazole (0.2, 1, 5 and 25 mg/kg BW), diethylhexyl phthalate (10, 50 and 250 mg/kg BW), nonylphenol (10, 50, 100 and 250 mg/kg BW), octylphenol (10, 50 and 250 mg/kg BW), and diethylstilbestrol (10, 20 and 40 micro g/kg BW) were orally administered to 4-week-old Sprague-Dawley rats for 3 weeks daily. Although testosterone at a low dose (50 micro g/kg/day) increased the expression of 3 beta -HSD mRNA, it was significantly decreased in the rats treated with 200 or 1000 micro g/kg/day testosterone compared with the control group (P<0.05). Furthermore, ketoconazole, diethylhexyl phthalate, nonylphenol, octylphenol and diethylstilbestrol caused significant downregulation of 3 beta -HSD mRNA in the testes at all doses (P<0.05). However, flutamide remarkably increased the level of 3 beta -HSD mRNA in the testes (P<0.05). These results suggest that endocrine disruptors may influence androgen biosynthesis in the testes by alteration of 3 beta -HSD mRNA expression..