Neuroendocrine peptides of the gastrointestinal tract of an animal model of human type 2 diabetes mellitus

We studied ten obese diabetic mice (Umea/Bom-ob) and 10 homozygous lean controls aged 21 weeks. The concentration of several neuroendocrine peptides was determined by radioimmunoassay of tissue extracts of antrum, duodenum and distal colon. The neuroendocrine peptides that we investigated were: secretin, gastric inhibitory polypeptide (GIP), gastrin, motilin, peptide YY (PYY), somatostatin, vasoactive intestinal polypeptide (VIP), substance P, neurotensin, neuropeptide Y (NPY) and galanin. In the antrum, gastrin, somatostatin, VIP, substance P and NPY concentrations were significantly lower in obese diabetic mice than in the lean controls. There was no statistical difference between the obese mice and lean controls for neurotensin and galanin content. In the duodenum, the concentration of substance P was lower in the obese diabetic mice than in lean mice. There was no statistical difference between obese diabetic mice and lean controls regarding the concentration of secretin, GIP, motilin, gastrin, somatostatin, VIP, neurotensin, NPY or galanin. In the colon, the levels of PYY, somatostatin, VIP, substance P, NPY and galanin were significantly lower in the obese diabetic mice than the lean controls. The concentration of neurotensin in the obese mice did not differ from that in the lean controls. The present study showed that the neuroendocrine system is disturbed in an animal model of human type 2 diabetes and that this disturbance differs from that observed in other animal models of human type I diabetes. The present findings may have some implications for the gastrointestinal dysfunction observed in patients with type 2 diabetes.