Increased intake of ethanol and dietary fat in galanin overexpressing mice

Evidence suggests that the orexigenic peptide, galanin (GAL), in the hypothalamic paraventricular nucleus (PVN) has a role in stimulating the consumption of ethanol, in addition to a high-fat diet. This possibility was further examined in mutant mice that overexpress the GAL gene. Two sets of GAL-overexpressors (GALOE) compared with wild-type (WT) controls, maintained on laboratory chow and water, were trained to voluntarily drink increasing concentrations of ethanol, from 3 to 15%. In the GALOE versus WT mice, the results revealed the following: (1) a 35–40% increase in ethanol intake and ethanol preference, which was evident only at the highest (15%) ethanol concentration, in male but not female mice, and was seen with comparisons to littermate and nonlittermate WT controls, (2) a significantly larger, 60–75% increase in ethanol intake and ethanol preference after a day of food deprivation, again only in male GALOE mice, (3) no change in consumption of sucrose or quinine solutions in preference tests, and (4) a 55% increase in consumption of a fat-rich diet during a 2-h test period, in both male and female GALOE mice. These results obtained with overexpression of the GAL gene provide strong support for a physiological role of this peptide in stimulating the consumption of ethanol and a fat-rich diet. They reveal gender differences in the behavioral phenotype, which may reflect GAL's functional relationship to reproductive hormones in the stimulation of consummatory behavior.