Steroid Biosynthesis in Vitro by Dysgenetic Ovaries Induced by Neonatal Thymeetomy in Mice

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Abstract
The small dysgenetic gonads which are induced in mice by neonatal thymeetomy are characterized by predominance of interstitial cells and absence of corpora lutea and follicles. In addition, the animals have stimulated uteri and masculinization of the salivary gland. Since these latter features suggested an abnormal pattern of steroid formation in vitro, ovarian steroid biosynthesis was studied. When 10 nmoles of 3H-3β hydroxy- pregn-S-en-20-one, 14C-progesterone or 14C-17-hydroxyprogesterone was incubated with 5 or 10 mg of ovarian homogenates, androstenedione and testosterone were synthesized by the dysgenetic ovaries, while much less of these C19- steroids was formed by control ovaries of normal mice. Enzyme activities related to steroid conversion were also estimated. In homogenates, the activity of 20α-hydroxysteroid dehydrogenase per g tissue was found to be about 15 times higher in the control ovaries than in the dysgenetic ovaries, while 3β-hydroxysteroid dehydrogenase activity per g tissue was similar. The activities of 17- hydroxylase and the lyase per mg protein in the microsomes were much higher in the dysgenetie ovaries than in the control ovaries. These results seem to support our previous in vivo observations that the dysgenetic ovaries have the ability to produce abnormally large quantities of androgens. (Endocrinology93: 786, 1973)

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