Dual Effects of the Neurohypophysial Hormone on the Thyroid Activities of Mice

Abstract

Our previous experiments in rats have failed to demonstrate any stimulative effect of Pitressin on the thyroid activities but rather showed suppressive one, indicated by T/S ratio, 131I uptake, histological examination1) and plasma PB131I concentration2), as their parameters. CROSSON, FALCH and REICHLIN also reported the failure in stimulating the thyroids of rats by

Thyrotrophin-Releasing Factor: Purification, Mechanism and Blockage of Action (a Review)

“…Elevations of the hypothalamic TRF content in peripheral hypothy roidism, the thyroxine block of TRF action, and, last but not least, difficulties in explaining TSH regulation without the participation of some hypothalamic humoral influence testify in favor of the physio logical action of TRF. In spite of all this, the final proof can only be (and probably soon will be) afforded by elucidation o f its mole cular structure and by demonstrating the effect of a synthetic mole cule; even then, two of H arris' (44,45) points, i.e., 1. the demon stration of its presence in the blood of the hypophyseal portal system in greater amounts than in the general circulation; and 2. changes in this concentration following hypothalamic activation and in relation to adenohypophyseal activity, still require explanation.…”