Adrenergic mechanisms in the control of corticotrophin secretion

Although the data on the effects of adrenergic mechanisms on the secretion of ACTH had seemed confusing, most of the discrepancies are probably explicable on the basis of methodological differences. In the present state of knowledge, the following conclusions seem reasonable. (1) In both man and rat, activation of central alpha-1 adrenoceptors is followed by increased ACTH secretion and this mechanism is important in the control of secretion of this hormone under some physiological circumstances. (2) In man, peripheral circulating catecholamines do not stimulate ACTH secretion under physiological conditions. This conclusion probably also applies to the anterior pituitary corticotrophs of the rat. (3) In the rat, beta-2 adrenoceptor agonists stimulate the intermediate lobe by a direct action that is physiologically relevant. (4) The role of central beta and alpha-2 adrenoceptors requires further investigation.