Baclofen suppresses binge eating of pure fat but not a sugar-rich or sweet-fat diet

Baclofen is a γ-aminobutyric acid-B agonist that is known to reduce the intake of some drugs of abuse. Binge eating of sugar or fat has been shown to have behavioral and neurochemical similarities to drug abuse, and may be special cases suggestive of natural addiction. To determine whether a treatment for drug abuse would have an effect on binge eating, and if so, which type of food intake might be affected, this study compared the effects of baclofen on binge eating sucrose, fat, and a sweet-fat combination. Rats were maintained for 21 days on a schedule of 12-h daily access to (i) a 10% sucrose solution, (ii) vegetable fat, or (iii) a commercially available sweet-fat chow. A fourth group had only 2-h daily access to vegetable fat. All four experimental groups, plus a control group, had ad libitum access to water and standard rodent chow. Food intake was then measured after intraperitoneal administration of baclofen (0, 0.6, 1.0, or 1.8 mg/kg). Results showed that although there was no effect of drug on standard chow intake of rats in any group, baclofen stimulated binge eating of sweet-fat food, suppressed binge eating of pure fat (vegetable shortening) in the group with 2-h access, and had no effect on sucrose binges. These results support earlier findings of a suppressive effect of baclofen on binge eating of fat and introduce a new finding that the drug differentially affects binge eating of sucrose and a sugar-fat combination.