Adrenergic Regulation of Hypothalamic Neurosecretory Functions

Abstract

It may now be regarded as certain that the mediobasal hypothalamus controls the hormonopoietic functions ofthe anterior pituitary (at least in mammals and humans). The small neurosecretory cells of the mediobasal hypothalamus produce specific oligopeptide adenohypophysiotropic hormones. However, the reactions associated with an increase or decrease of one or another anteriorpituitary hormone secretion are often accompanied by marked changes in the functional activity of the large “Gomori-positive” cells of the anterior hypothalamus. In particular, intensification of the hypophyseal thyrotropic function, observed after thyroidectomy or cervical sympathectomy, in many cases coincides with an obvious decrease in the secretory activity of the supraoptic nucleus cells. In contrast, after an increase of antidiuretic hormone secretion (elicited, for example, by administration of hypertonic saline solutions) and hence, a rise in the Gomori-positive cell activity, the hypophyseal thyrotropic function decreases, and the thyroid shows signs of depression (ALESHIN, 1971, 1974). On the other hand, intensification of the hypophyseal adrenocorticotropic function (for example in response to stress or superior cervical sympathetic ganglia (GCS) stimulation) occurs simultaneously with a pronounced increase in the secretory activity of the supraoptic nucleus cells. These observations would support the hypothesis of a participation of this magnocellular nucleus in the regulation of adenohypophyseal hormonopoiesis by suppression of the pituitary thyrotropic function and stimulation of the adrenocorticotropic function. However, the Gomori-positive neurosecretory cells, the main function of which is control of the water metabolism and maintenance of the organism’s osmotic balance, do not participate directly in regulation of the anterior pituitary. Hence, involvement of Gomori-positive cells in the reactions controlled by the mediobasal hypothalamus suggests that both neurosecretory hypothalamic formations (the adenohypophysiotropic area of the mediobasal hypothalamus and the magnocellular nuclei of the anterior hypothalamus) are influenced by the same regulatory mechanisms.