STEROID PROFILES FORMED BY RAT ADRENOCORTICAL WHOLE TISSUE AND CELL-SUSPENSIONS UNDER DIFFERENT CONDITIONS OF STIMULATION

The production of five steroids, corticosterone, deoxycorticosterone (DOC), 18-hydroxydeoxycorticosterone (18-OH-DOC), 18-hydroxycorticosterone (18-OH-B) and aldosterone, has been measured following incubations of rat adrenal tissue. The following tissue preparations were used: whole gland minces, whole glands quartered, capsules and inner zones intact, or as cell suspensions. Stimulation by ACTH, LH and potassium was also studied. The steroid profile elaborated by the tissue varies in a striking manner depending both on the method of tissue preparation and on the mode of stimulation. In inner zones the variation is found in the relative amounts of corticosterone and 18-OH-DOC produced. In unstimulated cell suspensions, or in whole tissue subjected to preincubation, the corticosterone/18-OH-DOC ratio is less than 1, possibly as little as 0.2. After stimulation, or in other preparations the ratio can rise to as much as 1.6. In capsules, the most important effect is on the capacity to produce the 18-oxygenated steroids as a whole. Even under conditions of maximal stimulation by ACTH or potassium, this capacity is greatly impaired in cell suspensions compared with whole tissue, while corticosterone is unaffected. The findings are not compatible with the theory that ACTH (or other stimulants) act at a single site in the biosynthetic pathway. They are compatible with the view put forward from these laboratories over the years, that control of steroidogenesis is also effected through maintenance of separated pools of steroid within the tissue which have different metabolic fates. In particular it appears that the 18-oxygenated steroids (in contrast to corticosterone) may be sequestered within tissue stores, and that in part their secretion is controlled by release from such stores. © 1979.