Expression of 3beta-hydroxysteroid
dehydrogenase (3beta-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 3beta-HSD as a molecular marker for
androgen biosynthesis was analyzed in rat testes exposed to several
endocrine disruptors using a reverse transcription-polymerase chain reaction technique.
Testosterone [50, 200 and 1,000 microg/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 microg/kg BW) were orally administered to 4-week-old Sprague-Dawley rats for 3 weeks daily. Although
testosterone at a low dose (50 microg/kg/day) increased the expression of 3beta-HSD
mRNA, it was significantly decreased in the rats treated with 200 or 1,000 microg/kg/day
testosterone compared with the control group (P<0.05). Furthermore,
ketoconazole,
diethylhexyl phthalate,
nonylphenol,
octylphenol and
diethylstilbestrol caused significant downregulation of 3beta-HSD
mRNA in the testes at all doses (P<0.05). However,
flutamide remarkably increased the level of 3beta-HSD
mRNA in the testes (P<0.05). These results suggest that
endocrine disruptors may influence
androgen biosynthesis in the testes by alteration of 3beta-HSD
mRNA expression.