title: Addiction and its reward process through polymorphisms of the D2 dopamine receptor gene: a review.
abstract: Since 1990, association studies have amassed strong evidence implicating the D(2) dopamine receptor (DRD2) gene in alcoholism. Specifically, the TaqI A minor (A1) allele of the DRD2 gene has been associated with alcoholism. The DRD2 gene has also been found to be involved in other substance use disorders including cocaine, nicotine and opioid dependence, and obesity. Beyond association studies, pharmacologic studies have shown reduced brain D(2) dopamine receptor numbers in A1(+) allele carriers (A1A1 and A1A2 genotypes) compared to A1(-) allele carriers (A2A2 genotype). Through a number of other approaches, different phenotypes have also been identified in subjects with the A1(+) and A1(-) alleles. These include metabolic, neurophysiological, neuropsychological, personality, stress and treatment studies. It is hypothesized that in an effort to compensate for deficiencies in the dopaminergic system, substance abusers may seek to stimulate the mesocorticolimbic circuits of the brain, long thought to be important in behavioral reward and reinforcement. In effect, one form of the DRD2 gene, the A1 allele, renders the dopaminergic system inefficient and rewards substance abuse that increases brain dopamine levels.
authors.affiliation: Department of Psychiatry and Biobehavioral Sciences, and the Brain Research Institute, University of California, Los Angeles, CA USA.
authors.forename: E P
authors.initials: EP
authors.lastname: Noble
mesh_terms: D000437:Alcoholism / Q000235:genetics; D000483:Alleles; D016739:Behavior, Addictive / Q000235:genetics*; D001667:Binding, Competitive / Q000502:physiology; D001921:Brain / Q000378:metabolism; D003072:Cognition Disorders / Q000235:genetics; D015870:Gene Expression / Q000235:genetics*; D006801:Humans; D009765:Obesity / Q000235:genetics; D010468:Perceptual Disorders / Q000235:genetics; D010554:Personality Disorders / Q000235:genetics; D011110:Polymorphism, Genetic / Q000235:genetics*; D017448:Receptors, Dopamine D2 / Q000235:genetics* / Q000378:metabolism; D012201:Reward; D013028:Space Perception / Q000502:physiology; D019966:Substance-Related Disorders / Q000235:genetics*; D014029:Tobacco Use Disorder / Q000235:genetics; D014796:Visual Perception / Q000502:physiology
chemical_list: D017448:Receptors, Dopamine D2