Endocrine Abstracts

BACKGROUND: The reason for reduction in appetite following gastro intestinal bypass procedures in man and in animal models remains unclear. Rats following jejunum intestinal bypass eat significantly less compared to sham operated rats and this seem due to a transferable factor in plasma. Such a humoral factor may be a therapeutic option for obesity. PYY, produced from the distal small bowel and colon is elevated in man and rodents following small bowel resection and ilial bypass. PYY is also a highly selective agonist for the NPY Y2 receptor and causes reduction in food intake in man and rodent. This study aimed to evaluate PYY concentrations and reduction in food in a rat model of jejunum intestinal bypass. METHOD: 18 male Wistar rats of 300g were randomised to jejunum intestinal bypass (BP) or sham bypass operations (SBP). Food intake and weight were measured daily for 28 days. On day 28, following a 24 hour fast, blood was collected and PYY measured. RESULTS: Both groups lost similar amounts of weight post operation, but the SBP started regaining weight earlier. At the end of the study the SBP animals were 21% heavier than the BP group (p=0.0001). The food intake of the BP animals were 16% reduced in comparison to the SBP animals (p =0.01). There was no evidence of malabsorption based on faecal production in either group (p=0.7). The PYY levels in the fasted BP animals were 90 plus/minus 15 pmol/L (mean plus/minus SEM) and in the SBP animals 33 plus/minus 7 pmol/L (p <0.007). CONCLUSION: The PYY levels in the fasted BP rats were significantly elevated and in the postprandial range. The findings are consistent with PYY being the factor that causes the reduction in appetite and weight loss following gastro intestinal bypass procedures.