CHRONIC CEREBROVENTRICULAR GALANIN DOES NOT INDUCE SUSTAINED HYPERPHAGIA OR OBESITY

Acute central administration of galanin has been reported to increase fat consumption. These experiments were designed to test the hypothesi s that repeated injections of galanin would elicit hyperphagia and wei ght gain and that this response would depend on the available diet. Ma le Sprague-Dawley rats were fed high (56% energy) or low (10% energy) fat diets. Galanin (300 pmol) or saline vehicle was injected into the third ventricle twice daily for 7 days and three times daily for anoth er 6 days. On both the high-carbohydrate and high-fat diets, twice dai ly galanin increased daytime food intake, but there was a compensatory decrease in nighttime intake. The addition of a third, nighttime inje ction of galanin was ineffective in producing an increase in total 24- h intake. There was no significant increase in body weight during gala nin treatment in rats eating either diet although animals eating the h igh-fat diet gained more weight as reflected by a significant increase in epididymal fat pad weight. Galanin treatment had no effects on ser um insulin, glucose or corticosterone concentrations, measured at the end of the experiment. However, animals fed the high-fat diet had sign ificantly higher insulin concentrations at the time of sacrifice. Alth ough repeated central infusions of galanin reliably stimulated daytime intake of both diets, they failed to increase total daily energy inta ke or body weight.