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Serotonin, Norepinephrine, and the Hypothalamic Ventromedial Nucleus: a Proposed Mechanism Mediating Hyperphagia and Obesity

Description: Serotonin has been implicated as a modulator of feeding behavior. This experiment was designed to alter brain serotonin levels through dietary means in hypothalamic ventromedial-lesioned and unlesioned rats. Daily food, water, and animal weights were measured. The purpose was to determine if VMH lesions altered the feeding pattern found in unlesioned rats. Although food intake for tryptophanenriched diets and tryptophan-deficient diets did not differ from their respective control groups, in some cases gross animal weights did differ significantly between experimental and control groups and between lesioned and unlesioned groups. A proposed model explains how a "low" energy signal and a "high" protein signal cycles amino acids through gluconeogenesis to comPensate for an energy deficit.
Date: May 1981
Creator: McDermott, Kathy Howard
Partner: UNT Libraries

Role of Calcium and Phospholipids in Transepithelial Sodium Ion and Water Transport in Amphibian Epithelia

Description: The present investigation is concerned with determining the role of calcium, phospholipids, and phospholipid metabolites on transepithelial sodium and water transport in response to antidiuretic hormone (ADH). These studies utilize the frog skin for determining sodium transport and amphibian urinary bladder for water flow measurements and scanning electron microscopy of cell surface morphology. The results demonstrate that phospholipids and phospholipid metabolites containing arachidonic acid stimulate transepithelial sodium transport through amiloride sensitive channels and the action of these lipids involves the synthesis of prostaglandins. These lipids also inhibited the increase in water flow induced by ADH, and this effect was prevented with prostaglandin synthesis inhibitors. Prostaglandins alter intracellular calcium concentrations and agents effecting calcium metabolism alter cell surface morphology and the changes in surface substructure induced by ADH. These observations support the hypothesis that alterations in membrane permeability to water and ions may involve metabolism of membrane phospholipids and prostaglandin biosynthesis.
Date: August 1983
Creator: Tarapoom, Nimman
Partner: UNT Libraries