In vitro metabolism of testosterone in hepatic tissue of a hagfish, Eptatretus burgeri

The metabolism of testosterone in hepatic tissue (combined microsomal and cytosol fractions) of a hagfish, Eptatretus burgeri, was examined in the presence of NADPH and in aerobic or CO-saturated atmosphere. The metabolites formed in CO atmosphere were identified as 4-androstene-3,17-dione, 5α-dihydrotestosterone, 3β-hydroxy-5α-androstan-17-one, and 5α-androstane-3β,17β-diol. From formation of these metabolites of testosterone, the activities of 5α-reductase, 3β- and 17β-hydroxysteroid dehydrogenases were indicated. Under aerobic condition, 7α-hydroxytestosterone, 7α-hydroxy-5α-dihydrotestosterone, 3β,7α-dihydroxy-5α-androstan-17-one and 5α-androstane-3β,7α,17β-triol were formed, in addition to 4-androstene-3,17-dione. These results demonstrate the presence of 5α-reductase, 3β- and 17β-hydroxysteroid dehydrogenases and 7α-hydroxylase in the hagfish liver. Since the hagfish is regarded as a very primitive vertebrate, it may be suggested that these enzymes are phylogenetically old and that the 7α-hydroxylase represents one of the first forms of hepatic cytochrome P-450 appearing during development.