Acute Increase of Thyroid Hormone Secretion in Response to Cold and Its Inhibition by Drugs which Act on the Autonomic or Central Nervous System

Abstract

In an attempt to study the neural control of the pituitary—thyroid axis in response to cold, an a—adrenergic blocking agent (phentolamine), a tranquilizer (reserpine), an anticholinergic drug (artopine sulfate), anesthetics (phenobarbital and ether), and an analgesic drug (pentazocine) were administered to rats acclimatized to a high room temperature and the animals were then exposed to cold (4 c) for 30 min. Exposure of rats to cold produced an acute and marked increase of intrathyroidal colloid droplets, but this increase was blocked almost completely by the administration of phentolamine, reserpine, atropine sulf ate, phenobarbital and ether. Pentazocine was without effect in this respect. Since phentolamine, reserpine and atropine sulfate did not interfere with pituitary— thyroid responsiveness to thyrotropin—releasing hormone (TRH), it seemed that these 5 drugs specifically inhibited the neural mechanism involved in augmenting TRH release in response to cold.(Endocrinology92: 265,1973)