Quantitative and qualitative gender-related differences in jejunal glutathione S-transferase in the rat - Effect of testosterone administration

Gender-related differences and the regulation by testosterone of glutathion e S-transferase were studied in rat jejunum. We analyzed enzyme activity an d the relative content of GST subunits. Four experimental groups of adult r ats were studied: normal males, castrated males, castrated males injected w ith testosterone and normal females. Glutathione S-transferase activity was assayed using 1-chloro-2,4-dinitrobenzene and 1,2-dichloro-4-nitrobenzene as substrates. Differences in subunit composition among groups were evaluat ed by western blot analysis. The results demonstrated that 1-chloro-2,4-din itrobenzene conjugation rate is higher in normal males than in normal femal es and castrated males. Testosterone administration to castrated males rais ed the activity up to the level observed in normal males. No significant di fference in glutathione S-transferase activity towards 1,2-dichloro-4-nitro benzene was observed among groups. Western blot analysis revealed that male s and females differ in all subunits tested that is, rGSTA2, rGSTM1, rGSTM2 and rGSTP1, and that testosterone regulates the content of rGSTM1, rGSTM2 and rGSTP1. In conclusion, jejunal GST shows a gender-dependent regulation affecting both enzyme activity and subunit composition, and testosterone ap pears to be one of the factors involved. (C) 2000 Elsevier Science Inc. All rights reserved.