Addiction-like reward dysfunction and compulsive eating in obese rats: Role for dopamine D2 receptors

We found that development of obesity was coupled with the emergence of a progressively worsening brain reward deficit. Similar changes in reward homeostasis induced by cocaine or heroin is considered a critical trigger in the transition from casual to compulsive drug-taking. Accordingly, we detected compulsive-like feeding behavior in obese but not lean rats, measured as palatable food consumption that was resistant to disruption by an aversive conditioned stimulus. Striatal dopamine D2 receptors (D2R) were downregulated in obese rats, similar to previous reports in human drug addicts. Moreover, lentivirus-mediated knockdown of striatal D2R rapidly accelerated the development of addiction-like reward deficits and the onset of compulsive-like food seeking in rats with extended access to palatable high-fat food. These data demonstrate that overconsumption of palatable food triggers addiction-like neuroadaptive responses in brain reward circuitries and drives the development of compulsive eating. Common hedonic mechanisms may therefore underlie obesity and drug addiction.