An investigation of the neural mechanisms underlying the efficacy of the adjustable gastric band

Abstract

BackgroundThe mechanisms via which adjustable gastric band (AGB) surgery provides effective and durable weight loss remain unclear. ObjectivesThis study defines the role of sensory vagal fibers in the efficacy of the adjustable gastric banding using capsaicin to eliminate unmyelinated afferent fibers in the vagus nerve in a rodent model. SettingUniversity. MethodsA miniaturized AGB was fitted at the gastroesophageal junction of obese rats with either intact or sensory fiber depleted vagus nerves where deafferentation involved intraperitoneal (125 mg/kg) or topical (1% to the stomach) application of capsaicin. The extent of sensory fiber lesion was assessed using c-fiber-mediated reduction in cholecystokinin-induced feeding. Food intake, weight, and composition, as well as shifts in central neural activity (measured by elevation of Fos protein), were assessed after either control or AGB inflation with or without vagal deafferentation. ResultsAGB inflation caused a significant reduction in food intake, weight, and fat mass (P<.05) in obese rats. The effect of AGB on these parameters was prevented in capsaicin pretreated (vagal sensory lesioned) rats. Elevations in neural activity in the nucleus of the solitary tract and parabrachial nucleus after AGB inflation were ameliorated in capsaicin-treated rats. ConclusionVagal sensory fibers are integral to the efficacy of the AGB.