THE ROLE OF THE HYPOTHALAMUS IN THE CONTROL OF THYROID FUNCTION*

Abstract

FOR many years it has been suspected that the nervous system exerts a controlling influence on thyroid function. It has been difficult, however, to obtain unequivocal evidence of this influence. Denervation or transplantation of the thyroid gland does not seem to interfere significantly with its function; it has therefore been assumed that there is no direct secretomotor innervation. Since hypophysectomy will reduce thyroid function to a minimum and, conversely, the administration of pituitary extracts will increase thyroid activity, any neural control of the thyroid gland would in all probability be mediated through the pituitary gland. Several investigations have been made in the past of a possible hypothalamic influence on thyroid metabolism, but the criteria used were generally so inadequate that definite conclusions were not possible. These earlier investigations have been reviewed by Harris (1) and Ingram (2), hence an extensive discussion will not be undertaken here. A few experiments may be briefly noted, however.