Effect of administered 20 β-hydroxysteroid dehydrogenase on serum progesterone in the rat

Administration of 20 β-hydroxysteroid dehydrogenase from Streptomyces hydrogenans to rats either intravenously or intraperitoneally results in decreases in serum progesterone. Detectable quantities of the enzyme were present in serum 2 days after intravenous injection. Intraperitoneal injections of 1.3 to 1.9 units of enzyme were effective in reducing serum progesterone over a longer period of time than the corresponding i.v. injections despite the failure of the enzyme to be absorbed into blood in detectable amounts; the serum concentration 2 hours after injection was 23% of that present before injection. The response was similar in diestrous and proestrous rats.