Food-specific addictions: brain mechanisms and pharmacological treatment approaches

Abstract

This work was supported by University of Florida, the National Eating Disorders Association, and USPHS grant DA-03123. ! • Rats with a history of binge eating palatable foods show characteristics that resemble addiction to drugs of abuse, including craving, use despite averse consequences, and cross-sensitization to other drugs.1! • Rats with a history of sugar-bingeing have also exhibited symptoms of withdrawal, such as tremors and teeth-chattering, when sugar is no longer provided or when administered an opioid antagonist, naloxone.2 However, withdrawal has not been observed in rats that binge eat fat3, suggesting that fat may have a differential effect on brain mechanisms involved in addiction. ! • Withdrawal from nicotine has been associated with an increase in phosporylated cAMP response element-binding protein (pCREB) in the nucleus accumbens (NAc)4, a brain region associated with reward. Likewise, the neuropeptide galanin (GAL) has been shown to inhibit signs of opiate withdrawal in transgenic animals.5 Fat intake has been shown to increase GAL6, providing a potential mechanism by why which pCREB levels may be reduced. Exp. 1a was designed to investigate whether injections of GAL into the PVN may alter pCREB levels in the NAc. Exp. 1b was aimed at studying whether chronic or acute access to a high-fat diet (HFD) may also affect pCREB levels in the NAc.! • Due to the behavioral and neurochemical similarities between overconsumption of palatable food and addiction to drugs of abuse, pharmacological agents that have been used to treat drug addiction may also reduce addictive overeating. Previous findings from our laboratory have found balcofen, a GABA-B agonist that has been used to treat drug addiction7, to reduce binge consumption of palatable food in rats8, however, this was only seen in animals overeating fat. Exp 2 was designed to see if naltrexone, an opioid antagonist used to treat drug dependence9, would also reduce overconsumption of palatable foods and whether if administered together, this combination of drugs would limit consumption of multiple macronutrients. ! • Both GAL injections into the PVN and chronic fat consumption were associated with decreased accumbal levels of pCREB. !