The formation of 16,17-dihydroxylated C19 steroids from 10-dehydro C19 steroids in liver microsomes from male and female rats

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The metabolism of the following substrates in liver microsomes from male and female rats was studied: 4,16-[7α-3H]androstadien-3-one, 5,16-androstadien-3β-ol, 5α-[7α-3H]androst-16-en-3α-ol, 5α-androst-16-en-3β-ol, 16α,17α-epoxy-5α-androstan3α-ol, 16α,17α-epoxy-5α-androstan-3β-ol and 3β-hydroxy-5,16-pregnadien-20-one. Liver microsomes from male rats were considerably more efficient in converting the 16-dehydro-C19-steroids than were liver microsomes from female rats. Male liver microsomes metabolized 4,16-androstadien-3-one, 5α-androst-16-en-3α-ol and 5α-androst-16-en-3β-ol into isomers of 5α-androstane-3,16β,17α-triol and 3,17β-dihydroxy-5α-androstan-16-one whereas female liver microsomes formed isomers of both 5α-androstane-3, 16α,17β-triol and 5α-androstane-3,16β,17α-triol from the same substrates. 5,16-Androstadien-3β-ol was metabolized into 5-androstene-3β,16β,17α-triol by liver microsomes from male rats ; liver microsomes from female rats did not form any 16,17-dioxygenated steroids from this substrate. No 16,17-dioxygenated metabolites were formed from 3β-hydroxy-5,16-pregnadien-2o-one, neither with microsomes from male rats, nor with microsomes from female rats. When 16α,17α-epoxy steroids were used as substrates both male and female liver microsomes formed 16β,17α-dihydroxylated metabolites. The large sexual differences characterizing the metabolism of 16-dehydro C19 steroids in liver microsomes from rats make the conversions described suitable assay systems for studying factors that regulate sexual differences in microsomal oxygenation reactions.

Original languageEnglish (US)
Pages (from-to)179-188
Number of pages10
JournalBiochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism
Issue number1
StatePublished - Jan 19 1973

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Endocrinology

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