Blunted Vagal Cocaine- and Amphetamine-Regulated Transcript Promotes Hyperphagia and Weight Gain

Abstract

Summary: The vagus nerve conveys gastrointestinal cues to the brain to control eating behavior. In obesity, vagally mediated gut-brain signaling is disrupted. Here, we show that the cocaine- and amphetamine-regulated transcript (CART) is a neuropeptide synthesized proportional to the food consumed in vagal afferent neurons (VANs) of chow-fed rats. CART injection into the nucleus tractus solitarii (NTS), the site of vagal afferent central termination, reduces food intake. Conversely, blocking endogenous CART action in the NTS increases food intake in chow-fed rats, and this requires intact VANs. Viral-mediated Cartpt knockdown in VANs increases weight gain and daily food intake via larger meals and faster ingestion rate. In obese rats fed a high-fat, high-sugar diet, meal-induced CART synthesis in VANs is blunted and CART antibody fails to increase food intake. However, CART injection into the NTS retains its anorexigenic effect in obese rats. Restoring disrupted VAN CART signaling in obesity could be a promising therapeutic approach. : Lee et al. report that consumption of an obesogenic diet inhibits calorie-induced synthesis and release of the neuropeptide CART from sensory vagal neurons. CART knockdown in these neurons mimics the hallmarks of obesity, weight gain, and overeating. Bypassing the vagus nerve with central CART administration effectively reduces feeding in obese rats. Keywords: diet-induced obesity, neuropeptide, vagus nerve, food intake, cholecystokinin, nucleus tractus solitarii, NTS, ingestion, nodose ganglia, vagal afferent neurons