Inhibition of human and rat 11β-hydroxysteroid dehydrogenases activities by bisphenol A

Bisphenol A (BPA) is a potential endocrine disruptor. It has been shown that it can interfere with steroid biosynthesis and metabolism. However, the mechanism is unclear. The objective of the present study is to investigate the effects of BPA on two isoforms of 11 beta-hydroxysteroid dehydrogenases (11 beta-HSD1 and 11 beta-HSD2) in human and rat tissues. Human liver, rat testis microsomes as well as rat adult Leydig cells were used for measurement of 11 beta-HSD1 activity, and human and rat kidney microsomes for 11 beta-HSD2 activity. BPA inhibited human and rat 11 beta-HSD1 activities with the half maximal inhibitory concentrations (IC(50)s) of 14.81 +/- 0.06 mu M (mean +/- SEM) for human and 19.39 +/- 0.09 mu M for rat enzyme, respectively. BPA inhibited rat 11 beta-HSD1 activity in intact rat Leydig cells. BPA also weakly inhibited both human and rat 11 beta-HSD2 activities. At 100 mu M, BPA inhibited human and rat enzymes by 51.16% and 41.61%, respectively. In conclusion, BPA is an inhibitor for both 11 beta-HSD1 and 11 beta-HSD2, with selectivity against the type I enzyme. (C) 2012 Elsevier Ireland Ltd. All rights reserved.