ENHANCEMENT BY THYROXINE OF THE ADRENAL-STIMULATING EFFECT OF SOMATOTROPHIC HORMONE

Abstract

SUMMARY: Experiments on intact Sprague-Dawley rats indicate that the adrenal enlargement produced by somatotrophic hormone (STH) can be greatly augmented by simultaneous treatment with comparatively small doses of thyroxine. Within a certain dosage range, the corticotrophic effect of STH is even proportionate to the dose of thyroxine given. The adrenal enlargement produced by adrenocorticotrophic hormone (ACTH), on the other hand, is not enhanced by concurrent treatment with thyroxine. Attention is called to the fact that, in rats in which adrenocortical hypertrophy is produced, either by STH plus thyroxine or by ACTH plus thyroxine, many of the changes in the extra-adrenal organs, which are generally considered to be indicative of increased glucocorticoid production (inhibition of body weight gain, splenic atrophy, involution of the thymus and lymph nodes, inhibition of inflammatory exudate formation), do not parallel the increase in adrenal weight.