In vitro on an HCG responsive, testosterone secreting adrenal cortical adenoma

Clinical and biochemical investigation of a virilized woman has shown an adrenal cortical adenoma to be the source of elevated plasma testosterone levels and to be responsive to gonadotropin administration $\text{in vivo}$ (Givens et al.) (2). In the present study, the gonadotropin responsiveness and biosynthetic potential of the adenoma were evaluated $\text{in vitro}$. Incubation of minced adrenal tumor with hCG resulted in increased ¹⁴C-acetate incorporation into pregnenolone, progesterone, dehydroepiandrosterone (DHA), androstenedione, and testosterone. Androstenedione and testosterone were the major products, accounting for 27% and 20% respectively of the total radio-activity added, when ³H-pregnenolone was incubated with homogenized tissue. Estrogen synthesis was not observed in the tumor. The adenoma contained 9.0 μg/g testosterone and 1.9 μg/g androstenedione as determined by radio immunoassay. 17β-hydroxysteroid oxido-reductase was active in the adenoma. Androstenedione was reduced to testosterone at a rate of 0.6 μg/100mg/hr. Under the same conditions, reduction of estrone to estradiol was undetectable. The reductase activity was present in both the mitochondrial and microsomal fractions. NADPH was the required cofactor. When NADH was substituted, the rate was less than 10% of that with NADPH in both particulate fractions.The experimental results indicate the presence of steroid path-way(s) necessary to synthesize testosterone, and represent the first $\text{in vitro}$ demonstration of gonadotropin sensitive steroidogenesis in an adrenal cortical adenoma.