Neurochemical and behavioral responses to stress.

The relationship between the hypothalamic - pituitary - adrenocortical (HPA) and the sympathetic - adrenomedullary (SA) systems is discussed by considering their role at the central and peripheral level. HPA and SA responses are not independent of each other, which indicates a number of hormonal, monoaminergic and peptidergic reactions at the brain level. It is demonstrated that a number of interacting systems and feedback mechanisms take part in stress responses.