THE ADRENERGIC STRESS-RESPONSE IN FISH - CONTROL OF CATECHOLAMINE STORAGE AND RELEASE

In fish, the catecholamine hormones adrenaline and noradrenaline are r eleased into the circulation, from chromaffin cells, during numerous ' stressful' situations. The physiological and biochemical actions of th ese hormones (the efferent adrenergic response) have been the focus of numerous investigations over the past several decades. However, until recently, few studies have examined aspects involved in controlling/m odulating catecholamine storage and release in fish. This review provi des a detailed account of the afferent limb of the adrenergic response in fish, from the biosynthesis of catecholamines to the exocytotic re lease of these hormones from the chromaffin cells. The emphasis is on three particular topics: (1) catecholamine biosynthesis and storage wi thin the chromaffin cells including the different types of chromaffin cells and their varying arrangement amongst species; (2) situations el iciting the secretion of catecholamines (e.g. hypoxia, hypercapnia, ch asing); (3) cholinergic and non-cholinergic (i.e. serotonin, adrenocor ticotropic hormone, angiotensin, adenosine) control of catecholamine s ecretion. As such, this review will demonstrate that the control of ca techolamine storage and release in fish chromaffin cells is a complex processes involving regulation via numerous hormones, neurotransmitter s and second messenger systems. (C) 1998 Elsevier Science Inc. All rig hts reserved.