Adrenal Protein Synthesis and Corticosteroid Production in Man 1

Abstract

An intimate association between adrenal protein synthesis and the ACTH stimulation of corticosteroid production has been suggested on the basis of several careful studies (1, 2). The exact relationship between protein synthesis and hormone action has not been clearly defined, and most of the attempts to study this relationship have been done in vitro utilizing adrenals from animal sources. A previous attempt to study the association between protein synthesis and adrenal function in man was done in vivo with patients receiving fluorinated pyrimidines as cancer chemotherapy (3). Under the conditions of the study, it was impossible to demonstrate that the fluorinated pyrimidines had an inhibitory effect on adrenal function. Since species differences exist with regard to adrenal function, it was of interest to study the relationship in man between adrenal protein synthesis and corticosteroid production in vitro.

Material and Methods. Adrenals were obtained at the time of operation from three patients undergoing bilateral adrenalectomy for Cushing's Disease. The glands were hyperplastic with a combined weight of 15 g in two cases, and 23 g in the other. Histological examination revealed generalized hyperplasia in two instances and cortical nodular hyperplasia in one. The glands were kept in ice immediately after removal and sectioned in a Stadie-Riggs microtome within 30 min.

Approximately 125 mg of adrenal tissue was preincubated in Krebs-Ringer-bicar-bonate buffer (KRB) at 37° for 15–30 min. The buffer was changed, 1.0 μCi of ¹⁴C-leucine (0.1 mM final concentration) was added, and the incubation was carried out for 120 min. Various flasks also contained ACTH 1 U/ml, cyclic AMP 2.5 mM, cyclo-heximide 1.0 mM, or testosterone 100 μg/ml. In some instances 0.5-ml aliquots of incubation medium were removed at 30-min intervals. At the end of the incubation, the adrenal tissue was homogenized in 10% TCA with 0.5% ¹²C-leucine, and the medium along with a subsequent wash was saved for steroid determination.