My long term objectives are to understand the effects of hormones on the brain and behavior. Specifically, I am seeking support to study the effects of aldosterone on brain and behavior. Aldosterone is a steroid hormone secreted from the adrenal gland during bouts of body fluid depletion which plays a fundamental role in sodium homeostasis. Aldosterone also generates an appetite for salt. Excess salt intake is a clinical hazard for cardiovascular and renal diseases and is a matter of concern for the general welfare. Steroids are known to have profound effects on the central nervous system, e.g. on sexually dimorphic brain regions, and on neurochemical regulatory responses to imbalances in homeostatis. I plan to use modern neuroendocrine techniques in analyzing the behavioral effects of aldosterone's action on the brain, specifically the cortico-medial region of the amygdala. These will include electrolytic lesions, systemic and central hormone treatment, protein synthesis changes and autoradiographic receptor studies, and neuroanatomical analysis. Specifically, I will 1) study in detail the effects of the medial amygdala lesions on aldosterone-induced and sodium depletion and renin- angiotension-induced salt hunger, 2) to test the idea that the appetite can be elicited by direct application of the hormone to this brain region, 3) to study the cellular mechanisms of aldosterone's action on brain cells by looking at the role of protein synthesis changes in the expression of the hormone induced appetite, 4) to study by autoradiographic techniques changes in aldosteroen receptors following sodium depletion, and 5) to further analyze the antomical connectivity of this brain region which may play a role in the execution of the behavioral end point-the ingestion of salt and the restoration of body fluid homeostasis. The combined approach should provide fundamental data about a neuroendorine system which organizes a basic biological drive, salt hunger.
