FUNCTIONAL ZONATION OF THE ADRENAL CORTEX: PATHWAYS OF CORTICOSTEROID BIOGENESIS

Abstract

Direct proof that aldosterone is produced by the glomerulosa of beef and rat adrenals has recently been provided. In the present investigation, the functional zonation of beef adrenal cortex has been further studied in vitro. When progesterone, desoxycorticosterone and corticosterone are added to the incubationmedia of beef adrenal slices they are metabolized in radically different ways depending on whether the slices originate in the glomerulosa (G) or in the fasciculata-reticularis (F.R.). I n the presence of tissue taken from G these steroids increase the production of aldosterone. Desoxycorticosterone increases the formation of corticosterone both in G and F.R. Progesterone enhances the production of hydrocortisone in F.R. only, whereas it increases corticosterone and aldosterone production in G. 21-hydroxypregnenolone increases the production of aldosterone in G and that of corticosterone in both G and F.R. 17α-hydroxyprogesterone and 17α-hydroxy-11-desoxycorticosterone markedly enhance the production of hydrocortisone in F.R. and lead to the formation of this compound in G where normally it is not formed. Progesterone, desoxycorticosterone and corticosterone increase the production of aldosterone by G to the same extent. These findings provide indirect evidence for an enzymatic specificity within the different types of cortical cells which is responsible for the anabolism of different types of hormones from a possibly identical precursor. Thus, the evidence tends to indicate the occurrence of 18-oxygenation in G but not in F.R., of 17- hydroxylase activity in F.R. but not in G, and that of 3β-dehydrogenase activity and 11- and 21-hydroxylase activities in both.