-
Views
-
Cite
Cite
N. KELLER, U. I. RICHARDSON, F. E. YATES, Protein Binding and the Biological Activity of Corticosteroids: In Vivo Induction of Hepatic and Pancreatic Alanine Aminotransferases by Corticosteroids in Normal and Estrogen-Treated Rats, Endocrinology, Volume 84, Issue 1, 1 January 1969, Pages 49–62, https://doi.org/10.1210/endo-84-1-49
Close - Share Icon Share
A new hypothesis concerning the physiological role of corticosteriod-binding proteins is proposed: These proteins increase the specificity of the adrenocortical system by determining the distribution of corticosteroid signals. Increases in the levels of the binding proteins are postulated to distribute adrenocortical hormonal signals toward organs with proteinpermeable vascular beds. The hypothesis was found to have physicochemical consistency by computer simulation of the multiple mass action and transport equations involved. Liver and pancreas of the rat appear to be members of 2 different classes of corticosteroid-sensitive target tissues. The enzyme alanine aminotransferase (AAT) is corticosteroid-inducible in both tissues, yet when transcortin levels and the total corticosteronecorticosterone concentration are both increased by prolonged estrogen treatment, only the hepatic enzyme responds with increased activity. Hepatic and pancreatic AAT were also induced in both sexes by dexamethasone, a synthetic steroid which is more potent than corticosterone. In contrast, corticosterone, which is more extensively bound in the plasma of females than of males, increases the enzymes in male liver and pancreas and female liver, but not in the female pancreas. The failure of the dexamethasonesensitive enzyme in the female pancreas to respond to a dose of corticosterone which is effective in the liver of both sexes and in the pancreas of the male rat was assumed to be based on the increased binding of corticosterone by the plasma of females. (Endocrinology84: 49, 1969)
