Striatal dopamine regulates systemic glucose metabolism in humans and mice

Lorcaserin is a selective serotonin 2C receptor agonist that could be useful in reducing body weight. In this double-blind clinical trial, we randomly assigned 3182 obese or overweight adults (mean body-mass index [the weight in kilograms divided by the square of the height in meters] of 36.2) to receive lorcaserin at a dose of 10 mg, or placebo, twice daily for 52 weeks. All patients also underwent diet and exercise counseling. At week 52, patients in the placebo group continued to receive placebo but patients in the lorcaserin group were randomly reassigned to receive either placebo or lorcaserin. Primary outcomes were weight loss at 1 year and maintenance of weight loss at 2 years. Serial echocardiography was used to identify patients in whom valvulopathy (as defined by the Food and Drug Administration) developed. At 1 year, 55.4% of patients (883 of 1595) receiving lorcaserin and 45.1% of patients (716 of 1587) receiving placebo remained in the trial; 1553 patients continued into year 2. At 1 year, 47.5% of patients in the lorcaserin group and 20.3% in the placebo group had lost 5% or more of their body weight (P<0.001), corresponding to an average loss of 5.8+/-0.2 kg with lorcaserin and 2.2+/-0.1 kg with placebo during year 1 (P<0.001). Among the patients who received lorcaserin during year 1 and who had lost 5% or more of their baseline weight at 1 year, the loss was maintained in more patients who continued to receive lorcaserin during year 2 (67.9%) than in patients who received placebo during year 2 (50.3%, P<0.001). Among 2472 patients evaluated at 1 year and 1127 evaluated at 2 years, the rate of cardiac valvulopathy was not increased with the use of lorcaserin. Among the most frequent adverse events reported with lorcaserin were headache, dizziness, and nausea. The rates of serious adverse events in the two groups were similar. In conjunction with behavioral modification, lorcaserin was associated with significant weight loss and improved maintenance of weight loss, as compared with placebo. (Funded by Arena Pharmaceuticals; ClinicalTrials.gov number, NCT00395135.) 2010 Massachusetts Medical Society

Obsessive-compulsive disorder (OCD) is a chronic psychiatric disorder that affects 2% of the general population. Even when the best available treatments are applied, approximately 10% of patients remain severely afflicted and run a long-term deteriorating course of OCD. To determine whether bilateral deep brain stimulation of the nucleus accumbens is an effective and safe treatment for treatment-refractory OCD. The study consisted of an open 8-month treatment phase, followed by a double-blind crossover phase with randomly assigned 2-week periods of active or sham stimulation, ending with an open 12-month maintenance phase. Academic research. Patients Sixteen patients (age range, 18-65 years) with OCD according to DSM-IV criteria meeting stringent criteria for refractoriness to treatment were included in the study. Treatment with bilateral deep brain stimulation of the nucleus accumbens. Primary efficacy was assessed by score change from baseline on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). Responders were defined by a score decrease of at least 35% on the Y-BOCS. In the open phase, the mean (SD) Y-BOCS score decreased by 46%, from 33.7 (3.6) at baseline to 18.0 (11.4) after 8 months (P < .001). Nine of 16 patients were responders, with a mean (SD) Y-BOCS score decrease of 23.7 (7.0), or 72%. In the double-blind, sham-controlled phase (n = 14), the mean (SD) Y-BOCS score difference between active and sham stimulation was 8.3 (2.3), or 25% (P = .004). Depression and anxiety decreased significantly. Except for mild forgetfulness and word-finding problems, no permanent adverse events were reported. Bilateral deep brain stimulation of the nucleus accumbens may be an effective and safe treatment for treatment-refractory OCD. isrctn.org Identifier: ISRCTN23255677.

Microdialysis studies in animals have shown that addictive drugs preferentially increase extracellular dopamine (DA) in the n. accumbens (NAc). Brain imaging studies, while extending these finding to humans, have shown a correlation between psychostimulant-induced increase of extracellular DA in the striatum and self-reported measures of liking and 'high' (euphoria). Although a correlate of drug reward independent from associative learning and performance is difficult to obtain in animals, conditioned taste avoidance (CTA) might meet these requirements. Addictive drugs induce CTA to saccharin most likely as a result of anticipatory contrast of saccharin over drug reward. Consistently with a role of DA in drug reward, D2 or combined D1/D2 receptor blockade abolishes cocaine, amphetamine and nicotine CTA. Intracranial self-administration studies with mixtures of D1 and D2 receptor agonists point to the NAc shell as the critical site of DA reward. NAc shell DA acting on D1 receptors is also involved in Pavlovian learning through pre-trial and post-trial consolidation mechanisms and in the utilization of spatial short-term memory for goal-directed behavior. Stimulation of NAc shell DA transmission by addictive drugs is shared by a natural reward like food but lacks its adaptive properties (habituation and inhibition by predictive stimuli). These peculiarities of drug-induced stimulation of DA transmission in the NAc shell result in striking differences in the impact of drug-conditioned stimuli on DA transmission. It is speculated that drug addiction results from the impact exerted on behavior by the abnormal DA stimulant properties acquired by drug-conditioned stimuli as a result of their association with addictive drugs.