Resistance to the nitrogen-mobilizing, diabetogenic action of cortisol in a small wallaby (Setonix brachyurus).

Abstract

Abstract Treatment with coritsol acetate at dose rates of 1 mg/kg for 3 days, then 5 mg/kg for a further 4 days, had no effect on urinary N excretion by female quokkas, although the higher dose was associated with an abrupt, minor increase in the males, which declined immediately after treatment. These dose rates raised plasma cortisol concentration to or above those found during stress or maximal ACTH stimulation. Treatment with ACTH at 5 IU/kg/day caused an early, minor increase in urinary N excretion by both sexes which declined to control values during the 5-day treatment period, even though plasma corticosteroid concentration was significantly raised. Treatment with 5 mg cortisol acetate/kg for 5 days had no effect on fasting plasma glucose concentration and caused a small but significant increase in the hypoglycemic effect of insulin. It is suggested that the minor changes in urinary N excretion were more likely a consequence of changes in renal clearance than tissue N metabolism and that the quokka, like the red kangaroo, is resistant to the nitrogen-mobilizing, diabetogenic actions of glucocorticoids.