PATHWAYS OF CORTICOSTEROID BIOSYNTHESIS BY HOMOGENATES OF ADRENAL TISSUE FROM RABBITS STIMULATED WITH ADRENOCORTICOTROPIN

The mechanism by which adrenocorticotropic hormone stimulates rabbit adrenal tissue to produce cortisol was investigated by following the time course of the metabolism of pregnenolone-4-14C by homogenates of adrenal tissue from adrenocorticotropin-stimulated rabbits. Both on the basis of 14C content and total mass of products formed the sequence of intermediates between pregnenolone and cortisol appeared to be 17α-hydroxy pregnenolone, 17α-hydroxyprogesterone, and 11-deoxycortisol, although the data did not permit the definite exclusion of 17α,21-dihydroxypregnenolone as a possible intermediate between 17α-hydroxypregnenolone and 11-deoxycortisol. The rate of progesterone and corticosterone formation exceeded that of 17α-hydroxypregnenolone and cortisol, respectively. Results of incubations in which 1.0 μmole of unlabeled 17α-hydroxypregnenolone or 17α-hydroxy progesterone was included as traps were consistent with the metabolic pathway from pregnenolone to cortisol indicated by the time-course studies. © 1969, American Chemical Society. All rights reserved.