Adrenergic Manipulation and Thyrotropin-Releasing Hormone (TRH)-Induced Thyrotropin (TSH) Release1

Abstract

At weekly intervals, five healthy volunteers received 100 μg of synthetic thyrotropin releasing hormone (TRH) 60 min into a four-hr infusion of each of the following agents: normal saline, isoproterenol, phentolamine, norepinephrine, and propranolol. Plasma thyrotropin (TSH) was determined serially in all five subjects, while in two plasma cortisol and growth hormone were also determined. Neither ∝ or β adrenergic stimulation nor blockade affected TRH induced TSH release and the mean maximal incremental rise of TSH during all infusions was not significantly different from the saline control. Plasma GH remained undetectable in both subjects in whom it was measured and plasma cortisol remained constant in one subject while in another a small but significant rise occurred after TRH, irrespective of infusion.