Avenues of investigation for the role of catecholamines in anxiety.

Many of the cardinal somatic symptoms associated with anxiety states are produced by the sympathoadrenal medullary discharge of catecholamines (CA) described over 50 years ago as 'fight or flight' responses. During the last decade, development of sensitive convenient assays for CA and their metabolites in tissues, cerebrospinal fluid, plasma and urine has made possible assessment of brain and peripheral adrenergic activity during stress, in neuropsychiatric disorders, and after administration of drugs. Studies in animal models of stress and anxiety parallel studies in humans. In rats, there are genetic differences in the graded adrenergic alerting responses to administered or anticipated stress, analogous to trait anxiety in humans. Behavioral responses to stress may be attenuated in rats by pharmacological blockade of peripheral CA release, suggesting a positive feedback process in which released CA augment behavioral responses, possibly analogous to use of clonidine or beta-adrenergic blocking agents to diminish somatic symptoms attending anxiety-provoking situations in humans. The biochemical evaluation of adrenergic responses by examination of CA and their metabolites in body fluids of humans with various levels of sympathetic activation will be discussed.