Regulation of delta 5-3 beta-hydroxysteroid dehydrogenase-isomerase activity in adrenocortical cell cultures by adrenocorticotropin.

Δ⁵-3β-Hydroxysteroid dehydrogenase-isomerase activity was found to decay in primary cultures of normal rat adrenocortical cells maintained in the absence of adrenocorticotropin for more than 7 days. Physiological concentrations of adrenocorticotropin induced the enzyme complex with a lag period of about 4 hours. Studies with actinomycin D and cycloheximide suggested that both RNA and protein synthesis are required for the induction of steroid dehydrogenase-isomerase activity.