STEROID METABOLISM BY ADULT RAT ADRENOCORTICAL CELLS IN MONOLAYER CULTURE

Abstract

SUMMARY The patterns of exogenous steroid metabolism by rat adrenocortical zona fasciculata and zona reticularis cells cultured together as a monolayer have been examined. In the continued presence of corticotrophin (ACTH), the cultured cells synthesized corticosterone, 18-hydroxydeoxycorticosterone and deoxycorticosterone from [3H]pregnenolone. In the prolonged absence of ACTH, however, [3H]pregnenolone was metabolized mainly to progesterone, 20α-dihydroprogesterone, 20α-hydroxy-5α-pregnan-3-one and 5α-pregnane-3β,20α-diol with small amounts of 5α-pregnane-3,20-dione, 11β-hydroxyprogesterone and 11β-hydroxy-20α-dihydroprogesterone, while virtually no corticosterone, 18-hydroxydeoxycorticosterone or deoxycorticosterone were produced. While 5-ene-3β-hydroxysteroid dehydrogenase-isomerase activity persisted at a substantial level in unstimulated cells and the 11β- and 18-hydroxylases were reduced but still present, 21-hydroxylase activity was almost completely lost when ACTH was omitted from the culture medium. These changes in enzyme activities were completely reversed by the addition of ACTH, cyclic AMP or dibutyryl cyclic AMP to unstimulated cultures for 4–5 days, during which time no proliferation of adrenal cells was observed.