Progesterone metabolism by major salivary glands of rat—II. Parotid gland

Abstract

The metabolism of [4- 14C]progesterone in the parotid salivary glands of nonpregnant female, pregnant female and male rats was investigated in vitro. The metabolic activity of the male rats was significantly lower than in either of the female groups. The pregnant group was metabolically more active than the nonpregnant female group, but this difference was not statistically significant. In homogenates and soluble fractions the main metabolite was 20α-hydroxy-4-pregnen-3-one in female rats. In male rats the main metabolites were 20α-hydroxy-4-pregnen-3-one and 3α-hydroxy-5α-pregnan-20-one in homogenates and 20α-hydroxy-4-pregnen-3-one in soluble fractions. In the microsomal fractions of both sexes polar compounds predominated. The results indicated the presence of at least the following progesterone metabolizing enzymes in rat parotid salivary glands: 3α-, 3β-, 20α- and 20β-hydroxysteroid dehydrogenase, 5α- and 5β-steroid hydrogenase and 17α-steroid hydroxylase activities. In the homogenates and soluble fractions of female rats 20α-hydroxysteroid dehydrogenase activity was significantly higher than in males.