Corticosteroidogenesis in Isolated Adrenal Cells of Rats. I. Effect of Corticotropins and 3′,5′-Cyclic Nucleotides on Corticosterone Production

By the use of trypsin digestion, a modified method for the preparation of isolated adrenal cells (IAC) from the rat has been described. The response of IAC to varying concentrations of ACTH,¹ β^1-24-corticotropin (Synacthen) and the ribonucleoside 3′,5′-cyclic phosphate of adenosine (c-AMP), cytidine (c-CMP), guanosine (c-GMP), inosine (c-IMP), thymidine (c-TMP), and uridine (c-UMP), as well as N⁶-2′-O-dibutyryl-adenosine-3′,5′-monophosphate (dc-AMP), has been assessed by measuring corticosterone production. ACTH, Synacthen, c-AMP, dc-AMP, c-IMP and c-GMP all stimulated corticosteroidogenesis in IAC. The halfmaximal dose calculated from their respective sigmoid dose-response curves for ACTH, Synacthen, c-AMP, dc-AMP, c-IMP and c-GMP was 6 μU, 70 pg, 2.3 μumoles, 0.08 μmole, 2.5 μmoles, and 8.0 μmoles/ml of incubation, respectively. The noncyclic ribonucleoside-5′-phosphate of adenosine, guanosine and inosine, as well as c-TMP, c-UMP and c-CMP, had no steroidogenic effect on IAC. Hormones such as glucagon, insulin, proinsulin, epinephrine and growth hormone had no effect on IAC in the presence or absence of ACTH. Cycloheximide, but not actinomycin D, blocked the steroidogenic effect of ACTH and dc-AMP in IAC. These results suggest that the continued presence of the cycloheximide-sensitive factor is important in the corticosteroidogenic properties of ACTH in IAC. These studies demonstrate the suitability of IAC for carrying out biochemical investigations and suggest that in IAC other cyclic nucleotides, in addition to c-AMP, may play a role in the mediating action of ACTH. (Endocrinology88: 1109, 1971)