Vagal innervation of intestine contributes to weight loss After Roux-en-Y gastric bypass surgery in rats.

Background: It is conceivable that overstimulation of chemo- and mechano-sensors in the Roux and common limbs by uncontrolled influx of undigested nutrients after Roux-en-Y gastric bypass surgery (RYGB) could lead to exaggerated satiety signaling via vagal afferents and contribute to body weight loss. Because previous clinical and preclinical studies using vagotomy came to different conclusions, the aim was to examine the effects of selective and histologically verified celiac branch vagotomy on reduced food intake and body weight loss induced by RYGB.

Methods: Male Sprague-Dawley rats underwent either RYGB + celiac branch vagotomy (RYGB/VgX, n=15), RYGB + sham celiac branch vagotomy (RYGB/Sham VgX; n=6), Sham RYGB + celiac branch vagotomy (Sham/VgX; n=6), or sham RYGB + sham celiac branch vagotomy (Sham/Sham; n=6), and body weight, body composition, and food choice were monitored for 3 months after intervention.

Results: In rats with RYGB, histologically confirmed celiac branch vagotomy significantly moderated weight loss during the first 40 days after surgery, compared to either sham or failed vagotomy (P<0.05). In contrast, celiac branch vagotomy slightly, but non-significantly, reduced body weight gain in sham RYGB rats compared to sham/sham rats. Furthermore, the significant food intake suppression during the first 32 days after RYGB (P<0.05) was also moderated in rats with verified celiac branch vagotomy.

Conclusions: The results suggest that signals carried by vagal afferents from the mid and lower intestines contribute to the early RYGB-induced body weight loss and reduction of food intake.