Effect of the posterior pituitary hormone on the function of the thyroid gland.

Abstract

1. In male albino rats, adapted to live at29.5°C. for a period of more than 8weeks, and then exposed to cold environmental temperature between10°and 15°C. for 10 days, a rise in oxygen consumption occurred. The histological picture of the thyroid indicated hyperactivity of the gland. However, change in the level of PBI was small.2. In the heat adapted rats, which were successively given vasopressin or oxytocin, there was no significant change in oxygen consumption. However, the level of PBI became lower in the case of vasopressin but not in the case of oxytocin. Histological picture indicated a slightly depressed activity of the thyroid after vasopressin and also after oxytocin.3. Rats were adapted to live at29.5°C. for the same time and then exposed to cold temperature between10°C and15°C. for10days and they were successively administered with the posterior pituitary hormone during a period of cold exposure. In the case of vasopressin the rate of rise in oxygen consumption and the level of PBI were remarkably lower than that of control ones which were exposed to cold but not given any vasopressin. Histological examination also showed an evidence of inhibitory effect on increasing of thyroid activity due to cold exposure. In the case of oxytocin these effects were hardly found.