Biomodulators of glucocorticoid: amplifiers and suppressors of glucocorticoid action.

We have found several compounds that specifically modulate the action of glucocorticoid in vivo and in vitro without themselves having any glucocorticoid-like action and have proposed the concept of "Glucocorticoid Action Biomodulators". These biomodulators consist of "Glucocorticoid Sensitivity Amplifier" (GSA), "Glucocorticoid Potency Amplifiers" (GPAs), and suppressors of glucocorticoid action. GSA increased the incorporation of glucocorticoid into the liver and its binding to cytosol receptor without changing the total receptor concentration in liver cytosol and the equilibrium constant of the glucocorticoid binding reaction. GPAs, potent activators of protein kinase C, markedly enhanced the glucocorticoid action and the glucocorticoid action was inhibited by the inhibitors of protein kinase C. H-7, an inhibitor of protein kinase C, inhibited the translocation of glucocorticoid-receptor complex into nuclei without affecting the extent of phosphorylation of glucocorticoid receptor. These findings suggest that GPA(s) and the suppressors modulate some protein(s) which regulates the translocation of glucocorticoid receptor into nuclei.