Steroid Hormone Influences on Cyclic AMP-Generating Systems

This chapter reviews the evidence that steroids influence the activity of the cyclic adenosine monophosphate (cAMP)-generating system and describes the structure and function of adenylate cyclase. Steroid hormones, especially glucocorticoids, have profound effects on the biochemistry of liver and fat tissues, and steroid regulation of cAMP metabolism in cells derived from liver and adipose tissues has been known for some time. Adrenalectomy also makes the liver refractory to cAMP-induced glycogenolysis and gluconeogenesis, whereas glucocorticoid replacement allows intracellular cAMP to once again stimulate glucose metabolism. Although regulation of cAMP levels by glucocorticoids in adipocytes differs in some ways from that in the liver, the general story is very much the same––namely, effects at both the level of cAMP and in postadenylate cyclase, cAMP-dependent biochemical phenomena. However, steroid regulation differs somewhat among the tissues, in that adrenalectomy has a biphasic effect on adenylate cyclase in adipose tissue, with an initial increase followed by a long-term decrease.