CORTICOSTERONE-INDUCED INSULIN-RESISTANCE IS NOT ASSOCIATED WITH ALTERATIONS OF INSULIN-RECEPTOR NUMBER AND KINASE-ACTIVITY IN CHICKEN KIDNEY

Chicken renal insulin receptors have been recently characterized; thei r number and kinase activities vary in response to altered nutritional status. In the present study, the effect of chronic corticosterone tr eatment was examined in 5-week-old chickens. The development of an ins ulin resistance following corticosterone was suggested after 1 and 2 w eeks of treatment by a significant decrease in the hypoglycemic effect of exogenous insulin and after 2 weeks by significant increases in pl asma insulin levels (1.63 +/- 0.13 vs 0.56 +/- 0.14 ng insulin/ml in c ontrols) and in renal cytosolic phosphoenolpyruvate carboxykinase acti vity (17.2 +/- 0.8 vs 13.7 +/- 0.7 nm/mn/mg tissue in controls). No si gnificant changes were present at the level of insulin receptor number and kinase activity. Therefore, in kidney and, as previously observed , in muscles, corticosterone can induce insulin resistance at postrece ptor steps in the cascade of events leading to insulin action. (C) 199 4 Academic Press, Inc.