Effect of Epinephrine on Metabolism of Thyroxine by Pituitary and Brain

Abstract

Summary

The influence of epinephrine on the metabolism of thyroxine (T4) by brains, pituitaries, kidneys, and sera of I¹³¹-radiothyroidectomized mice was studied with I¹³¹-labeled T4. All mice received I¹³¹-labeled T4, and half also received epinephrine. Several organs were then investigated chromato-graphically, each at the same two time intervals. Kidneys and sera indicated I^- and T4; brain and pituitaries indicated I^-, T4, and triiodothyronine (T3). These results confirm findings previously reported. This study has also provided evidence that epinephrine increases conversion of T4 to T3 in the brain. For this reason, a new mechanism is postulated to explain how epinephrine might affect uptake and release of I¹³¹ by the thyroid gland.