Catecholamines and stress.

The subject of catecholamines and stress has occupied researchers for many years and filled many books. A brief revew such as this cannot cover such a broad topic. Instead, provided here are a few concepts, reflecting somewhat different viewpoints from those in standard textbooks. The first of these concepts is that there are three distinct peripheral catecholamine systems, each with different effectors, regulation, and roles. The three systems are the sympathetic nervous system, adrenomedullary hormonal system, and DOPA-dopamine autocrine/paracrine system. This contrasts with the traditional concept, promulated by WALTER B. CANNON, of a unitary sympathoadrenal system. It also contrasts with the notion of HANS SELYE that release of “adrenalines” characterizes the acute phase of what he called the “General Adaptation Syndrome.” Both these investigators held to the view that all forms of stress lead to the same stereotyped response. Indeed, in line with this “doctrine of nonspecificity,” SELYE defined stress as the nonspecific response of the body to any demand imposed upon it [1]. According to a relatively new concept, however, stress responses have a primitive kind of specificity, with differential responses of the sympathetic nervous and adrenomedullary hormonal systems, depending on the type and intensity of the stressor as sensed by the organism and interpreted in light of experience [2]. Another concept in this paper that contrasts with CANNON'S teachings is that instead of the sympathetic nervous system becoming active only in emergencies, tonic sympathetic nervous outflows to several vascular beds, organs, and glands maintain levels of a variety of monitored variables, both under resting conditions and in response to everyday challenges such as orthostasis, locomotion, the post-prandial state, and altered temperature. This paper also notes a closer association between the hypothalamo-pituitary-adrenocortical system and adrenomedullary hormonal system in several forms of stress than between the sympathetic nervous and adrenomedullary hormonal systems (Table 1). In fainting, adrenomedullary activation with concurrent sympathoinhibition precedes and may precipitate the acute neurocirculatory collapse. Finally, offered for consideration here is the notion that stress and distress can contribute to acute and chronic diseases, by worsening independent pathologic states and inducing “allostatic load.” These concepts may provide a theoretical basis for scientific integrative medicine in the post-genome era.