Control of body weight by lower gut signals.

The importance of the terminal ileum in the control of food intake and body weight was studied in rats made obese by VMH knife cuts and in lean controls. In the first study, 35 rats had either jejunoileal bypass, antibiotic infusion into the bypassed segment, resection of the bypassed segment of sham operation. All three experimental treatments reduced food intake and produced large and statistically equivalent weight losses compared to the sham surgery control. Apparently, physiological signals or bacterial toxins arising in the bypassed segment are not essential to the loss of body weight. In the second study, 38 rats had either 5 or 10 cm segments of the terminal ileum transposed to mid-duodenum or upper jejunum or served as surgical controls. As in the previous study, the experimental rats reduced their food intake and sustained a substantial loss of body weight. Stimulation of the terminal ileum with nutrient-rich chyme was sufficient to cause most of the weight loss seen after jejunoileal bypass.