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.
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.
Neurobiology of Nutrition Laboratory, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808, USA.
Andrew C
AC
Shin
Huiyuan
H
Zheng
Hans-Rudolf
HR
Berthoud
D000818:Animals; D001069:Appetite Regulation / Q000502:physiology*; D004195:Disease Models, Animal; D004734:Energy Metabolism / Q000502:physiology*; D015390:Gastric Bypass; D006503:Hepatic Veins / Q000294:innervation; D008099:Liver / Q000098:blood supply / Q000294:innervation*; D008297:Male; D009767:Obesity, Morbid / Q000601:surgery*; D011169:Portal Vein / Q000294:innervation*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D016896:Treatment Outcome; D014628:Vagotomy; D014630:Vagus Nerve / Q000502:physiology* / Q000601:surgery; D015431:Weight Loss / Q000502:physiology*