This project was initiated to study the role of Catecholamines in the central and peripheral system in experimental and genetic hypertension and stress, and has now been extended to study the participation of other biogenic amines, estrogens, and prostaglandins in the central regulation of neurovegatative functions. Central catecholamines, histamine, serotonin and several neuropeptides are involved in the regulation of spontaneous and sodium-sensitive genetic hypertension. There are specific and selective changes in catecholamine metabolism in hypothalamic and brain stem nuclei in genetic, sodium dependent hypertension in the rat, and in sodium depleted dogs. There are large changes in catecholamine metabolism in the heart and adrenal medulla of genetic, sodium sensitive hypertensive rats. Specific binding of prostaglandin E2 has been described in rat brain membranes. Electrical stimulation of selective cerebellar nuclei produces increases in plasma catecholamines.