Roles of Catecholamines in the Regulation of Stress-induced Hypothalamo-Pituitary Adrenal(HPA) axis Stimulation

It is generally recognized that central nervous 1; ystem plays an essential role in the regulation of synthesis and release of ACTH. It is now firmly estabilished that the hypothalamus is the focal point at which neural stimuli converge to influence the secretion of ACTH, and the median eminence is regarded as the final common path through which information is transmitted to the anterior pituitary. In recent years, efforts have been directed toward and progress has been made in identifying some of the neurotransmitters that control the release of corticotropin-releasing factor (CRF). Among them, monoaminergic neural systems in the hypothalmic control of pituitary function have been widely studied. A possible role of brain catecholamines in the regulation of ACTH secretion has been con sidered by numerous investigators. The cate cholamines are not per se the hypothalamic corticotropin releasing factors (Saffran and Schal1y, 1966; Guillemin and Rosenberg, 1965; Martini et aI. , 1960; Fischer and Moriarty, 1977) . Several groups of investigators have reported increased adrenal corticosteroid secretion following the injection of catecholamines directly into the brain (Endrocozi et aI. , 1963; Krieger and Krieger, 1966). On the other hand numerous studies have failed to support an excitatory role of brain catecholamines in the regulation of ACTH secretion but have led to the opposite (Smelik, 1967; Carr and Moore , 1968; Van Loon et aI. , 1971a,b,c; Scapagnini et aI. , 1970, 1971; Ganong et aI., 1976; Ganong, 1977; Buckingham and Hodges , 1977; Steiner and Grahame-Smith, 1980) . This study was undertaken to try to clarify the role of catecholamines (norepinephrine and dopamine) in the hypothalamo-pituitary-adrenocortical response to stress. Thε aims of the present study ￦ere to check the kinetic parameters of turnover of catecholamines as well as steady state concentrations before and after ether stress