Varenicline increases striatal dopamine D2/3 receptor binding in rats

Increasing dopamine D-2/3 receptor availability is postulated to be a treatment for drug addiction. Varenicline, an alpha 4 beta 2-nicotinic partial agonist, is effective for nicotine dependence. We hypothesize that varenicline increases dopamine D-2/3 receptor availability. Twenty male drug-naive rats were randomized to varenicline (2 mg/kg) or placebo for 14 days, and then injected with the dopamine D-2/3 radiotracer I-123-IBZM. We found significantly higher striatum-to-cerebellum binding ratios in both dorsal and ventral striatum for the varenicline group compared with placebo. Varenicline increases dopamine D-2/3 receptor availability in drug-naive rats. Therefore, varenicline may be an effective treatment for addictions other than smoking.