THE SYMPATHETIC NERVOUS SYSTEM AS A HOMEOSTATIC MECHANISM. II. EFFECT OF ADRENOCORTICAL HORMONES ON BODY TEMPERATURE MAINTENANCE OF COLD-EXPOSED ADRENALECTOMIZED RATS

¹ Laboratory of Chemical Pharmacology, National Heart Institute, Bethesda, Maryland and Departments of Pharmacology and Psychology, Indiana University, Bloomington, Indiana

Intact rats exposed to low environmental temperature (4°C) maintain body temperature by piloerection, vasoconstriction, shivering and mobilization of glucose and free fatty acids. In contrast, totally adrenalectomized rats are unable to activate any of these systems; they lose body heat rapidly and die in a few hours when exposed to low temperature. The sugar- and lipid-mobilizing actions of exogenous catecholamines are also markedly reduced by adrenalectomy. The inability of adrenalectomized rats to survive in the cold can be reversed by acute treatment with glucocorticoids such as cortisone, dexamethasone or prednisolone or by chronic treatment with aldosterone. This treatment also restores responsiveness to catecholamines, suggesting that the adrenalectomized rat may be considered as a functionally sympathectomized animal because of impaired responsiveness of effector systems which normally are activated by sympathetic function.