Reward circuitry dopaminergic activation regulates food and drug craving behavior

Abstract

Neural circuits implicated in drug conditioning, craving and relapse overlap extensively with those involved in natural reward and reinforcement like food. Exposure to drug-related cues in human addicts results in drug craving and localized activation of central circuits that are known to mediate cue-induced reinstatement of drug-seeking behavior in animal models of relapse. Similar regional activation patterns occur in humans in response to cues associated with foods. Furthermore, drug- and food-related cues not only activate common neuroanatomical regions but also result in similar activity-regulated gene expression programs within these shared areas. Cues predictive of food availability are powerful modulators of appetite as well as food-seeking and ingestive behaviors. The upregulation of a number of early genes in unique patterns within corticostriatal, thalamic, and hypothalamic networks suggests that food cues are capable of powerfully altering neuronal processing in areas mediating the integration of emotion, cognition, arousal, and the regulation of energy balance. The dopaminergic, enkephalinergic, and fos gene expressions are important regulatory genetic pathways for food craving behaviors. An umbrella term to describe common genetic antecedents of multiple impulsive, compulsive and addictive behaviors is Reward Deficiency Syndrome (RDS). Individuals possessing a paucity of serotonergic and/or dopaminergic receptors and an increased rate of synaptic dopamine catabolism, due to high catabolic genotype of the COMT gene, are predisposed to self-medicating any substance or behavior that will activate dopamine release including alcohol, opiates, psychostimulants, nicotine, glucose, gambling, sex, and even excessive internet gaming, among others. Finally, utilizing the long term dopaminergic activation approach will ultimately lead to a common safe and effective modality to treat RDS behaviors including aberrant food and drug craving behaviors.