In Vivo Effect Of Duodenal Infusion On Glucose Metabolism In Nesfatin-1 Knockout Rats

Backgroud:Nesfatin-1 is an anorectic peptide containing 82 amino acid residues encoded by the N-terminal region of the protein precursor Nucleobindin 2（NUCB2）,which is involved in mediating feeding and energy metabolism.It is highly conservative between humans and rodents.Nesfatin-1 is widely expressed in the gastrointestinal tract and can enter the brain from the periphery through non-saturated transmembrane diffusion.It is reported to induce satiety,resulting in weight loss,thereby improving insulin sensitivity.With the deepening of the research on nesfatin-1,it is found that nesfatin-1 is not only involved in food intake,but also involved in the regulation of glucose metabolism and energy metabolism.Objective:To investigate the effect of intestinal infusion on glucose metabolism in nesfatin-1 knockout rats.Methods:The nesfatin-1 heterozygotes were mated with heterozygotes,and the wild type（SD）and homozygous(Nucb2^-/-)of the littermate were used in this experiment.A duodenal infusion model was established.Intestinal infusion group of 10-week-old homozygous rats were defined as follows:Saline group,Nesfatin-1 group（Nucb group）,Tetracaine group（Tetrac group）,Tetracaine+nesfatin-1 Group（Tetrac+Nucb group）,Saline group and Nesfatin-1 group of fasted re-feeding,GLP-1 receptor antagonist-Exending Fragment 9-Group 39（Ex-9 group）,Exending Fragment 9-39+nesfatin-1 group（Ex-9+Nucb group）.The intestinal perfusion model were performed at 10 weeks of age,carotid artery and catheterization,fed on three-day high fat diet（3Days-HFD）,SD and Nucb2^-/-rats were divided into:Saline group,Glucose group and Lipid group.A insulin resistance model was initiated at6 weeks of age in rats,which were fed on HFD for 10weeks（10Week-HFD）.SD and Nucb2^-/-rats were divided into Saline group,Glucose group and Lipid group after modeling.Pancreaticeuglycemic clamps,glucose tolerance test GTT,insulin tolerance test（ITT）and other methods were used to evaluate the effect of intestinal infusion on glucose metabolism in each group of rats.Plasma lipid and insulin levels were measured by ELISA.The level of insulin receptor in rat liver was measured by Western blot.Results:The glucose infusion rate（GIR）was significantly higher in the nesfatin-1 group than in the saline group,but after infusion of tetracaine+nesfatin-1,GIR returned to the the level of control group.Compared with Saline group,fasting and refeeding with infusion of nesfatin-1 reduced food intake and blood glucose in rat.The Ex-9+nesfatin-1 group had a lower GIR than that of the nesfatin-1 group which was statistically significant.After a long period of HFD,the glucose infusion rate was significantly lower than that of the normal diet group,but there was no significant decrease in GIR in the three-days HFD group.Duodenal infusion of sugar and lipids can inhibit glucose production and increase glucose infusion,but this effect of knockout rats is weaker than that of SD rats.However,the GIR levels of three-days and 10-weeks HFD were no longer observed these results.Conclusion:Intestinal infusion of nesfatin-1 can increase insulin sensitivity.