Neuropeptide contents in the duodenum of non-obese diabetic mice

Twelve pre-diabetic and 12 diabetic female NOD mice aged 22-24 weeks were studied. As controls, 12 female BALB/cJ of the same age and sex were used. The duodenal content of several neuropeptides, namely vasoactive intestinal polypeptide (VIP), neurotensin, neuropeptide Y (NPY), galanin, gastrin-releasing peptide (GRP) and enkephalin was determined by radioimmunoassay of tissue extracts. The VIP content in duodenal extracts from both pre-diabetic and diabetic NOD mice was significantly higher than that of the controls. The enkephalin content of the duodenum of diabetic mice was significantly higher than that of the controls, while no significant difference was found between the controls and pre-diabetic mice. There was no statistically significant difference between controls and NOD mice regarding the duodenal content of neurotensin, NPY, galanin or GRP. It has been suggested that the high duodenal content of VIP appears to be primary to the onset of diabetes and that the high enkephalin content may be attributable to the diabetic state. The changes in the duodenal content of VIP and enkephalin reported here in an animal model for diabetes type I might be of relevance for the gastrointestinal complications occurring in human diabetes.