| Gastrointestinal tract is the main place of digesting and absorbing nutritive materials in living organisms. Various stresses are apt to destroy the normal mucosa tissue structure of gastrointestinal tract and decrease the ability of absorbing and digesting nutritive materials. Previous studies showed that polypeptides growth factors, such as epidermal growth factor, transforming growth factor, insulin-like growth factor-1, took part in regulation of growth of intestinal epithelium and promoted regeneration and reparation of intestinal mucosa, but their clinical applications were limited due to the lack of tissue specificity and possible adverse reaction brought. Glucagon like peptide 2 (GLP-2) was discovered laterly, it could obviously and specifically promote intestinal tract to absorb nutritive materials, and more studies on the relations between GLP-2 and growth regulation of intestinal epithelium were reported in the recent decade.Moreover, it has been reported that GLP-2 promoted the development of normal small intestine and recovering of pathological intestinal mucosa. GLP-2 stimulates generation and restraints its apoptosis by GLP-2R distributing in the enterocyte, and also plays the recuperative role of protecting intestinal cells and promoting intestinal function by GLP-2R distributing in the other parts of intestine. GLP-2 implements its biological effect by combining with GLP2 receptor (GLP-2R). GLP-2R-mediated cAMP-dependent signal transduction and phosphatidyl inositol 3-kinase (PI3-K) and mitogen-activated protein kinase ( MAPK ) presumbly are involved in the various effects of GLP2. However, the mechanism remains unclear. In this study, we try to observe the proliferative effect of GLP2 and GLP2R expression in gastrointestinal tract.Objectives:The effect of GLP-2 on gastrointestinal mucosa is observed and expression and distribution of GLP-2R are examined in the different parts of different organs in mice.Methods:Male and healthy BALB/C mice (5-6 weeks old) weighing 17-20g are used. The mice are divided into control group (n=8) and GLP-2 treated group (n=9) randomly. GLP-2 treated group mice are given GLP-2 (250μg/kg) intraperitoneal injection twice per day for three days. Control group mice are given physiological saline intraperitoneal injection twice per day for three days. Three days later, mice are sacrificed and samples are taken in each group for morphological observations. The histological changes of gastrointestinal mucosa in mice are observed by dyeing with hematoxylin and eosin staining.The expression and distribution of GLP-2R in gastrointestinal tissue are detected by Immunohistochemistry.Results:1. After treating with GLP-2, the muscosa epithelium of stomach thickens and gastric pit deepens in mice.2. Mucosal villus in different section of small intestine grow obviously higher in GLP-2 treated group compared with control group (P<0.05); Villus in small intestinal segment grows higher, crypt deepens, and colon mucosa epithelium thickens.3. GLP-2R is widely expressed in each part of gastrointestinal tract in mice. The expression of GLP-2R is not observed in liver, lung, kidney and bladder.4. No difference was observed in the expression of GLP-2R between GLP-2 treated group and control group(P﹥0.05).Conclusions:1. GLP-2 is able to stimulate gastric mucosa and colon epithelium mucosa to grow and increase mucosal villus height in different section of small intestine.2. GLP-2R is widely expressed gastric, duodenal, jejunum, ileum and colon in mice, the expression of GL P-2R in liver,lung, kidney and bladder was not observed.3. There is no difference for GLP-2R expression in the gastrointestinal tract in the mice between the normal group and GLP-2 treated group.
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