Ontogeny of testicular steroid dehydrogenase enzymes in pig (3 alpha/beta-, 20 alpha- and 20 beta-): evidence for two forms of 3 alpha/beta-hydroxysteroid dehydrogenase.
Three enzymatic activities (3 alpha/beta-hydroxysteroid dehydrogenase, 20 beta- and 20 alpha-hydroxysteroid dehydrogenases) were measured in testes of pigs as a function of age. Earlier studies reported a highly purified 20 beta-hydroxysteroid dehydrogenase from neonatal pig testes that also showed strong 3 alpha/beta-hydroxysteroid dehydrogenase activity [Ohno et al., J. Steroid Biochem. Molec. Biol. 38 (1991) 787-794]. We report here that neonatal pigs testis is rich in 3 alpha/beta- and 20 beta-hydroxysteroid dehydrogenase activities, both of which fall to low levels (measured as specific activity) at 60 days. Thereafter the activity of 3 alpha/beta-reduction rises to high levels whereas 20 beta-reduction remains low. Activity of 20 alpha-reduction is of intermediate level in the neonate, falls to a nadir at 60 days and rises to high levels in the mature animal. Western blots of cytosolic proteins show that the bifunctional enzyme (3 alpha/beta-plus 20 beta-hydroxysteroid dehydrogenase) is high in neonatal testes and falls to low levels at maturity. It is proposed that the neonatal testis possesses the bifunctional enzyme which is replaced by a second enzyme at maturity, that is a 3 alpha/beta-hydroxysteroid dehydrogenase without 20 beta-reductase activity. The possible functional significance of these changes is considered.
Ohno
S
S
Department of Biochemistry, Faculty of Pharmaceutical Sciences, Hoshi University, Tokyo, Japan.
Nakajin
S
S
Shinoda
M
M
D015089:20-Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D043607:20-alpha-Hydroxysteroid Dehydrogenase; D015096:3-Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific); D000375:Aging / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D015153:Blotting, Western; D003349:Cortisone Reductase / Q000378:metabolism*; D008297:Male; D013552:Swine; D013737:Testis / Q000201:enzymology*
D015096:3-Hydroxysteroid Dehydrogenases; D015089:20-Hydroxysteroid Dehydrogenases; D043607:20-alpha-Hydroxysteroid Dehydrogenase; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific); D003349:Cortisone Reductase