The hypothalamic neurosecretory phenomena and the activity of thyroid gland in partially thyroidectomized rats.

In the present times, it has been strongly postulated, from various experimental data of stalk section or hypothalamic lesion, that the secretory maintenance and regulation of trophic hormone by the adenohypophysis have certain relationship to some neural mechanisms in hypothalamus, and that some chemical transmitters from hypothalamus are liberated into the adenohypophysis to exert a specific influence on its activity(Cahne and Cahne, 1938;Westmann and Jacobson, 1938;Brolin, 1947;Barrnett and Greep, 1951;Greer, 1951, 1952;Harris and Jacobson, 1952;Bogdanove and Halmi, 1953;Greer and Erwin, 1954;Harris, 1955; Ganong et al. , 1955;Yamada, 1957). In consideration of these facts, it should be mentioned that stalk section, a prolonged administration of posterior hormone, and total thyroidectomy(Purves and Griesbach, 1955)result in changes in the cytology of hypophyseal basophile cells which are responsible for production of thyrotrophic hormone. Since it seemed, from the above mentioned points, very likely that the activity of thyroid is more or less under the control of the neurosecretory activity of the hypothalamic nuclei, many investigaters have studied the effects of methylthiouracil (M. T. U. )and total thyroidectomy on the hypothalamic neurosecretion and thyroid gland(Shibusawa, et al. , 1956;Shiozaki, 1956;Yamada, 1957). In the present report, it is intended to clear up the problems related to the mechanisms regulating the pituitary thyroid axis by means of partial thyroidectomy of rats.