Food restriction markedly increases dopamine D2 receptor (D2R) in a rat model of obesity as assessed with in‐vivo μPET imaging ([¹¹C] raclopride) and in‐vitro ([³H] spiperone) autoradiography

Abstract

The lower D2R binding in Ob U than Le U rats observed with ARG most likely reflects decreases in striatal D2 receptors levels whereas the increased availability observed with muPET is likely to reflect reduced DA release (resulting in decreased competition with endogenous DA). Lack of a significant difference between Ob R and Le R suggests that the differences in dopamine activity and D2R levels between Ob and Le Zucker rats are modulated by access to food. The ARG finding of an attenuation of the age-related loss of D2R binding corroborates previous studies of the salutary effects of food restriction in the aging process. Because [11C] raclopride is sensitive to competition with endogenous DA, the higher D2R binding in obese rats with raclopride despite the lower D2R levels shown with spiperone could reflect lower extracellular DA in the Ob rats and merits further investigation.