Comparison of effect of environmental and preoptic heating and pyrogen on plasma cortisol

Abstract

-Elevation of preoptic temperature by means of implanted thermodes activated heat-loss mechanisms and produced a significant elevation of plasma cortisol levels in dogs. Both the temperature-regulatory response and the elevation in plasma cortisol were not sustained during continued preoptic warming. Sudden elevation of environmental temperature evoked a sustained temperature-regulatory response and elevation in plasma cortisol. Only a minimal elevation in cortisol was observed when environmental temperature was gradually raised. When bacterial pyrogen was injected, a more marked elevation in plasma cortisol occurred. Plasma cortisol began to rise before an appreciable rise in body temperature was present and declined while body temperature was still elevated.