Effects of baclofen and naltrexone, alone and in combination, on the consumption of palatable food in male rats.

Excess consumption of palatable food has been shown to affect reward-related brain regions, and pharmaceutical treatments for drug addiction may also be effective in treating overeating of such foods. The GABA-B agonist baclofen and opioid antagonist naltrexone have both been used to treat addiction, and have been shown to suppress intake of certain foods. The combination of these drugs has shown to be more effective in reducing alcohol consumption than either drug alone. The present study assessed the effects of naltrexone and baclofen, alone and in combination, on intake of foods comprised of various macronutrients. Male Sprague-Dawley rats were given 12-hr daily access to chow and a fat emulsion, sugar-fat emulsion, or a sugar solution for 21 days. Rats were then administered (intraperitoneal) baclofen-naltrexone combinations (0.1 mg/kg naltrexone and 1.0 mg/kg baclofen, 1.0 mg/kg naltrexone and 1.8 mg/kg baclofen), and naltrexone (0.1, 1.0 mg/kg) and baclofen (1.0, 1.8 mg/kg) alone. The high dose of the baclofen-naltrexone combination reduced palatable food intake in both the fat and sugar-fat groups compared with vehicle, without affecting chow consumption in these groups. Naltrexone showed little significant effects on intake of either palatable food or chow. Baclofen also reduced palatable food intake in the fat and fat-sugar groups, but differences were only noted between the low and high dose. The combination of baclofen and naltrexone may be a useful tool in selectively targeting the consumption of high-fat and sugar- and fat-rich foods.