[Role of dopamine in the regulation of the thyrotropic function of the pituitary gland].

Acute experiments on sexually mature mongrel male rats showed that microinjection of dopamine into the area of paraventricular nucleus of the hypothalamus and the anterior lobe of the hypophysis failed to influence the secretion from the hypophysis of the thyrotropic hormone (TTH), the content of which was determined radioimmunologically. Dophamine injections in the mediobasal hypothalamus decreased the TTH content in the blood of euthyroid rats. In animals given thyroxin preliminarily, an increase in the TTH level occurred in the blood serum in response to dophamine administration into the mediobasal hypothalamus. A conclusion was drawn that dophamine of the mediobasal hypothalamus took part in the TTH secretion from the anterior lobe of the hypophysis. The normalizing action of the given mediator is expressed under conditions of the changed functional activity of the hypophysis-thyroid gland system.