Vagal Innervation of the Hepatic Portal Vein and Liver Is Not Necessary for Roux-En-Y Gastric Bypass Surgery-Induced Hypophagia, Weight Loss, and Hypermetabolism.
Shin, Andrew C. PhD; Zheng, Huiyuan PhD; Berthoud, Hans-Rudolf PhD
[Article] Annals of Surgery. 255(2):294-301, February 2012.

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Objective: To determine the role of the common hepatic branch of the abdominal vagus on the beneficial effects of Roux-en-Y gastric bypass (RYGB) on weight loss, food intake, food choice, and energy expenditure in a rat model.

Background: Although changes in gut hormone patterns are the leading candidates in RYGB's effects on appetite, weight loss, and reversal of diabetes, a potential role for afferent signaling through the vagal hepatic branch potentially sensing glucose levels in the hepatic portal vein has recently been suggested in a mouse model of RYGB.

Methods: Male Sprague-Dawley rats underwent either RYGB alone (RYGB; n = 7), RYGB common hepatic branch vagotomy (RYGB HV; n = 6), or sham procedure (sham; n = 9). Body weight, body composition, meal patterns, food choice, energy expenditure, and fecal energy loss were monitored up to 3 months after intervention.

Results: Both RYGB and RYGB HV significantly reduced body weight, adiposity, meal size, and fat preference, and increased satiety, energy expenditure, and respiratory exchange rate compared with sham procedure, and there were no significant differences in these effects between RYGB and RYGB HV rats.

Conclusions: Integrity of vagal nerve supply to the liver, hepatic portal vein, and the proximal duodenum provided by the common hepatic branch is not necessary for RYGB to reduce food intake and body weight or increase energy expenditure. Specifically, it is unlikely that a hepatic portal vein glucose sensor signaling RYGB-induced increased intestinal gluconeogenesis to the brain depends on vagal afferent fibers.

(C) 2012 Lippincott Williams & Wilkins, Inc.