9319097 Engeland Stress Activates the neuroendocrine system through a feedback mechanism involving the hypothalamic-pituitary-adrenal system. Corticotropin releasing factor, a peptide hormone, is released from the hypothalamus and travels to the pituitary where it triggers the release of adrenocorticotropic hormone (ACTH). ACTH travels in the blood to the adrenal glands where it stimulates the release of glucocorticoids, such as cortisol and corticosterone. This system is also involved in the maintenance of the body's normal internal functioning. Glucocorticoids not only help the body respond to stress but play an integral part of daily life and adaptation to environmental change. Recently, Dr. Engeland and others have found changes in plasma glucocorticoids in the absence of changes in plasma ACTH under both stressful and non-stress conditions. The finding challenges our simplistic view of adrenocortical secretion and indicates that other mechanisms are involved in the release of adrenal hormones. Recent evidence suggests a role for the adrenal nerves but the specific contribution of adrenal neural input to physiological responses are not known. Using a variety of innovative techniques, Dr. Engeland will characterize the contribution of adrenal neural activity to non-stress and stress- induced secretion of adrenal glucocorticoids. He will then determine which neurotransmitters are mediating its effect. Finally Dr.Engeland will identify the adrenal cellular mechanisms that mediate neural effects on steroidogenesis. These results will provide a new understanding about why exposure to the same environmental conditions that appear to have similar effects on ACTH release may produce different adrenocortical responses. The function of most tissues is dependent on the maintenance of normal plasma glucocorticoids levels. Aberrant adrenal hormone secretion can result in weaken muscles and suppressed organ systems. Understanding the nature of the interaction between adrenal nerve input and ACTH will provide a new perspective on physiological and pathological alternations in adrenocortical secretion. Thus, findings resulting from this basic research may eventually lead to the development of new pharmacological or surgical approaches to control adrenal secretion of glucocorticoids. ***
