Altered dopamine D2 receptor function and binding in obese OLETF rat.

Brain Res Bull

Department of Neural and Behavioral Sciences, The Pennsylvania State University, College of Medicine, Hershey, PA 17033, USA.

Published: January 2008

AI Article Synopsis

  • Research shows that obese individuals and drug addicts have decreased D2-like receptor (D2R) binding in the brain's striatum, raising questions about its impact on overeating.
  • In a study with OLETF rats, a model for diet-induced obesity, researchers found these rats had lower D2R binding in the brain compared to lean control rats, indicating altered receptor signaling.
  • Administration of the D2R agonist quinpirole affected locomotor activity and sucrose intake differently in OLETF rats than in lean ones, suggesting obesity may change how these receptors influence reward and eating behavior.

Article Abstract

A decrease in D2-like receptor (D2R) binding in the striatum has been reported in obese individuals and drug addicts. Although natural and drug rewards share neural substrates, it is not clear whether such effects also contribute to overeating on palatable meals as an antecedent of dietary obesity. Therefore, we investigated receptor density and the effect of the D2R agonist quinpirole (0.05, 0.5 mg/kg, S.C.) on locomotor activity and sucrose intake in a rat model of diet-induced obesity, the CCK-1 receptor-deficient Otsuka Long Evans Tokushima Fatty (OLETF) rat. Compared to age-matched lean controls (LETO), OLETF rats expressed significantly lower [125I]-iodosulpride binding in the accumbens shell (-16%, p<0.02). Whereas the high dose of quinpirole increased motor activity in both strains equally, the low dose reduced activity more in OLETF. Both doses significantly reduced sucrose intake in OLETF but not LETO rats. These findings demonstrate an altered D2R signaling in obese OLETF rats similar to drug-induced sensitization and suggest a link between this effect and avidity for sucrose in this model.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2225542PMC
http://dx.doi.org/10.1016/j.brainresbull.2007.07.019DOI Listing

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