Testosterone-metabolizing capacity and characteristics of adrenal microsomes in human fetus in vitro.

Hui Wang, Dan Xu, R X Peng, Jiang Yue

Index: J. Pediatr. Endocrinol. Metab. 23(1-2) , 143-52, (2010)

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Abstract

We describe the metabolite spectrum of testosterone (T) in human fetal adrenal in vitro, and verify possible roles of CYP3A and 2C isoforms of human fetal adrenal in T metabolism which respond to T metabolism in liver. Isolation and identification of T and its metabolites were carried out by isocratic high-performance liquid chromatography. CYP isoforms involved in T metabolism were examined by an inhibition study. Four metabolites formed by fetal adrenal microsomes were androstenedione (A), 16alpha-hydroxytestosterone (16alpha-HT), 16beta-hydroxytestosterone (16beta-HT) and 6beta-hydroxytestosterone (6beta-HT), which made up 61%, 25%, 12% and 2%, respectively, of the total. However, fetal liver microsomes produced six metabolites, which were, from high to low: A, 2alpha-HT, 6beta-HT, 2beta-HT, 16beta-HT and 16alpha-HT. Generation of A, 16alpha-HT and 16beta-HT in the adrenals was much greater than that in the liver. Erythromycin inhibited the formation of 6beta-HT and 16beta-HT with maximal inhibition of 76% and 47%. Sulfaphenazole and omeprazone had no inhibitive effect on the formations of T metabolites. The predominant metabolites of T in fetal adrenal, A and 16alpha-HT, were not decreased by these three inhibitors. These results suggest that the human fetal adrenal has greater T-metabolizing ability and a different metabolizing pathway from adult and fetal liver. Some other CYPs but not CYP3A7, CYP2C9 and CYP2C19 might play the most important part in the metabolism of T in human fetal adrenal although CYP3A7 is responsible for the formation of 6beta-HT and partly participates in the formation of 16beta-HT.