Effects of Substrates and Cofactors on Steroid Synthesis in Hyperplastic Adrenals

Abstract

Homogenized hyperplastic adrenal tissue from a 13-year-old boy with classic Cushing''s syndrome was incubated with either progesterone-4-14C or pregnenolone-7[alpha]-3h as substrate. The addition of DPN or a TPNH-generating system to the incubation medium resulted in almost quantitative conversion of substrate to metabolites. The presence of added TPN and glucose-6-phosphate favored the conversion of pregnenolone to cortisol and androstenedione. DPN favored the conversion of pregnenolone to progesterone and cortisol. Under none of these conditions was progesterone converted to androstenedione. Evidence is presented for the conversion of progesterone-4-14C to 16[alpha]-hydroxyprogesterone-14C and 16[alpha], 17-dihydroxyprogesterone-14C. 16[alpha]-Hydroxyprogesterone was formed from pregnenolone when DPN was added to the medium. The conversion of pregnenolone-7[alpha] -3h to 16[alpha] -hydroxypregnenolone-3H was demonstrated also. There was no evidence of a lack of any of the enzymes involved in the conversion of pregnenolone to steroid hormones; however, the activities of these enzymes varied considerably, depending upon the experimental conditions.