Bombesin reduces alcohol choice in nutritive expectancy and limited-access procedures

Bombesin is a bioactive tetradecapeptide found in nerves of the brain and gut and previously shown to inhibit intake of ethanol in forced-choice, one-bottle tests in water-deprived rats. In the present experiments, intraperitoneal bombesin (4-100 micrograms/kg) reduced selection of alcohol in two-bottle choice tests with water. In an application of the "nutritive expectancy" procedure, weight-reduced rats received access to 4% w/v ethanol and water. Bombesin injection suppressed the intake of ethanol, but not of water, in rats with prior ethanol experience. In an application of the "limited access" procedure, nondeprived rats received access to 6% w/v ethanol and water in nonhome cages during either the light or the dark phase of a 12:12 h lighting cycle. Bombesin injection lowered the intake of ethanol, but not of water, in both phases of the lighting cycle and in both sexes. Water deprivation is not necessary for bombesin to inhibit alcohol intake and this effect cannot be explained by hypodipsia, nonspecific debilitation, or conditioned aversion. Endogenous bombesin-like neuropeptides may specifically reduce choice of alcohol by signaling satiation with ethanol.