STUDIES ON THE THYROTROPIC HORMONE OF THE ANTERIOR PITUITARY

Abstract

A study of the physiologic activity of the thyrotropic hormone of the anterior pituitary has shown that the stimulating effect of the hormone on the thyroid gland is only temporary and that retrogressive changes actually take place in spite of continued injections of the hormone. Korenchevsky¹ injected rats with a glycerol extract of the anterior pituitary for periods of from six to eleven weeks. A decrease in the weight of the thyroid gland was found, which averaged 17 per cent below the control weight. Siebert and Smith² and Verzar and Wahl³ noted that the rise in metabolic rate of guinea-pigs injected with thyrotropic hormone reached a peak by the tenth day and then returned to the normal level. The latter showed that a marked drop in basal metabolic rate occurred when the hormone was injected into thyroidectomized guinea-pigs. Houssay, Biasotti and Mazzocco⁴ have reported that anterior