On the role of cyclic AMP and cyclic GMP in steroid production by bovine cortical cells.

The time course of corticotropin-induced steroidogenesis and changes in intracellular cyclic AMP and cyclic GMP levels were investigated in isolated bovine adrenocortical cells prepared by trypsin digestion. Corticotropin produced a peak rise in cyclic AMP during the first 5 min of stimulation and enhanced steroid production after 15 min. Corticotropin also caused a decrease in cortical cyclic GMP at 5 min; this decrease in cyclic GMP reverted to a 2-3 fold increase at 15-30 min which gradually subsided by 60 min. A steroidogenic concentration of prostaglandin E2 also produced an elevation in the levels of both nucleotides, but the rise in cyclic GMP preceded the rise in cyclic AMP. These results suggest that the relative amounts of cyclic AMP and cyclic GMP, rather than the absolute levels of cyclic AMP, may be a key factor in the regulation of steroidogenesis.