Distribution And Expression Of Nesfatin-1/NUCB2 In The Digestive System Of Dogs

Nesfatin-1 is an 82 amino acid polypeptide derived from NUCB2,which is the precursor of nesfatin-1 including signal peptide of 24 amino acid and protein of 396 amino acid.These amino acid sequences are highly conserved across species.NUCB2 can be cleaved into three fragments by prohormone convertase: that is nesfatin-1(1–82 aa),nesfatin-2(85–163 aa)and nesfatin-3(166–396 aa).It plays important roles in regulating food intake and energy homeostasis.The expression of nesfatin-1/NUCB2 protein and NUCB2 mRNA in the canine digestive organs were evaluated in present study.Through exploring the expression of nesfatin-1/NUCB2 in different digestion tissue,the research of the regulation in food intake and digestion will be abundant.The tissues of the digestive system were collected from twelve Chinese rural female dogs in good health at different developmental stages: infantile(1.5 M),juvenile(4.5 M),pubertal(7 M)and adult(10 M).Digestive organs such as esophagus,stomach,duodenum,jejunum,ileum,cecum,colon,rectum,liver and pancreas were removed.One part of them were fixed in 4% paraformaldehyde,processed for conventional paraffin by a microtome with five-?m-thick slice,detected by immunohistochemistry,were observed under an optical microscope and photographed.Another part of them were put in to-80°C freezer.Then the expression of NUCB2 mRNA at the developmental stages was analyzed by real-time fluorescence quantitative PCR(qRT-PCR).The results showed that nesfatin-1 / NUCB2 protein was mainly distributed in the gastric glands of the stomach tissue,and the cells were irregular in shape(oval,tapered,triangular-shaped,etc.),which was similar to the endocrine cells;it was also distributed in the islet area and exocrine portions of the pancreas,but there was no expression in other digestive tissues.However,NUCB2 mRNA was found in all digestive organs.Quantitative PCR showed that NUCB2 mRNA had no significantly different among esophagus,stomach,duodenum,jejunum,ileum,cecum,colon,rectum and liver in infantile,juvenile,pubertal and adult dogs(P>0.05),but NUCB2 mRNA in pancreas was significantly higher compare to other tissues(P <0.05).On the same developmental stage of digestion organ,NUCB2 mRNA expression was the highest in the pancreatic tissue,followed by stomach tissue,and the other tissues expression levels were low(P <0.05).In the intestinal tissues,NUCB2 mRNA in juvenile dogs were significantly higher than pubertal dogs(P <0.05).We can conclude that nesfatin-1 / NUCB2 protein was mainly distributed in the stomach tissue of gastric glands,islets and exocrine pancreas of dog;NUCB2 mRNA expression in different developmental stages of canine digestive organs,in which the expression levels in the stomach and pancreatic tissues were higher than the other organizations.And the level of NUCB2 mRNA showed a downward trend from juvenile to pubertal dog.