Steroid 17-hydroxylation and androgen production by incubated rat adrenal tissue

Rat adrenal tissue was decapsulated, and capsules (considered to consist largely of zona glomerulosa) and inner zones were separately incubated with [4-¹⁴C]-progesterone. Testosterone was found to be formed by both tissue types in yields at least 1% of those of corticosterone, confirming earlier observations. In addition, evidence was found for the production of radioactive 17-hydroxyprogesterone. androstenedione, 11-deoxycortisol and cortisol, in addition to the usual 17-deoxysteroids. Yields of cortisol were up to 20% of those of corticosterone, yields of the other steroids were about the same as testosterone. No significant differences in the yields of these products were found in capsule and inner zone incubations. From endogenous precursors, cortisol was again found to be formed in similar amounts by both tissue types. In some incubations, testosterone was apparently produced in larger amounts by the capsules, in others amounts were similar in capsules and inner zones. Addition of ACTH (20 mU per ml) increased the yields of testosterone in capsules but not inner zones. Sodium depletion had no effect on testosterone production. It is concluded that 17-hydroxylation can and does occur in the rat adrenal cortex, and it is likely that the pathways for the formation of cortisol and the androgens are similar to those described for other tissues. It is unlikely that 17-hydroxylation occurs in the cells of the glomerulosa, but the evidence suggests that it may be prominent in a region of the fasciculata directly underlying the glomerulosa, in the position of the zona intermedia.