Hepatic vagotomy increases consumption of a novel-tasting diet presented immediately after surgery

To further characterize the possible effect of hepatic vagotomy on food intake, rats adapted to a medium-fat diet (MF diet) were offered a novel-tasting diet immediately after hepatic branch vagotomy (HBX rats) or sham vagotomy (SHAM rats) and food intake as well as diet selection (novel-tasting vs. familiar diet) was measured. When a novel-tasting sweet medium-fat diet (SMF diet) was offered immediately after surgery, HBX rats ate transiently more (days 1-4 after surgery) and selected more (days 5 and 6 after surgery) of the SMF diet than SHAM rats. Similar results were obtained when a novel-tasting bitter diet (AMF diet) was offered instead of the SMF diet. In contrast, when rats adapted to the AMF diet prior to surgery were given normal MF diet as novel-tasting diet immediately after surgery, HBX and SHAM rats' postoperative food intake and diet selection did not differ. When rats were given only MF or SMF diet before and after surgery, HBX and SHAM rats' food intake during the initial postoperative period also did not differ. The results indicate that hepatic branch vagotomy and sham vagotomy have different aversive effects which lead to transient differences in postoperative food intake when diets with a novel and strong taste are presented during the initial postoperative period. Therefore, information conveyed by the hepatic branch of the vagus can apparently lead to a conditioned feeding response. This is evidence for a more subtle role of the liver in the control of food intake than previously thought.