Progestogen metabolism by ovaries of the roach (Rutilus rutilus L.) and the rudd (Scardinius erythrophthalmus L.)

Roach ovaries converted 17-hydroxyprogesterone to 17,20α-dihydroxy-4-pregnen-3-one (17,20αP) and to glucuronides of testosterone and 17,20αP. Small amounts of 5α-pregnane-3α- and -3β, 17, 20α-triols, 7α-hydroxy-5α-reduced metabolites and 17,20β-dihydroxy-4-pregnen-3-one (17,20βP) were also formed. Rudd ovaries converted this substrate mainly to 17,20αP, 5α-pregnane-3α- and -3β,17,20α-triols, 17,20α-dihydroxy-5α-pregnan-3-one and testosterone glucuronide. The main metabolites of progesterone with both species were 17,20αP, 5α-pregnane-3β,17,20α-triol and 7α-hydroxy-5α-reduced steroids. Rudd ovaries formed, in addition, 17,20α-dihydroxy-5α-pregnan-3-one from progesterone. The pattern of metabolites was markedly altered when the concentration of substrate was increased from 42ng to 1 µg or 100 µg. At the highest concentration, glucuronides and polar steroids were not detectable, while at low concentrations they accounted for over 50% of the metabolites. 20α-Hydroxysteroid dehydrogenase was shown to have a very high capacity, producing 21-47 µg 17,20αP from 100 µg 17-hydroxyprogesterone substrate with 200 mg ovarian tissue in 5h.