Chronic cerebroventricular galanin does not induce sustained hyperphagia or obesity

Abstract

Acute central administration of galanin has been reported to increase fat consumption. These experiments were designed to test the hypothesis that repeated injections of galanin would elicit hyperphagia and weight gain and that this response would depend on the available diet. Male 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 another 6 days. On both the high-carbohydrate and high-fat diets, twice daily galanin increased daytime food intake, but there was a compensatory decrease in nighttime intake. The addition of a third, nighttime injection of galanin was ineffective in producing an increase in total 24-h intake. There was no significant increase in body weight during galanin treatment in rats eating either diet although animals eating the high-fat diet gained more weight as reflected by a significant increase in epididymal fat pad weight. Galanin treatment had no effects on serum insulin, glucose or corticosterone concentrations, measured at the end of the experiment. However, animals fed the high-fat diet had significantly higher insulin concentrations at the time of sacrifice. Although repeated central infusions of galanin reliably stimulated daytime intake of both diets, they failed to increase total daily energy intake or body weight.