| Background and ObjectiveOrthotopic Liver Transplantation(OLT)is the most effective treatment for end-stage Liver disease(eg: acute and chronic severe hepatitis,cirrhosis in the liver decompensation).Although the use of new immunosuppressant reduced the incidence of rejection after transplantation,but it increases the chance of infection and cancer.Blocking the portal vein during the anhepatic phase of orthotopic liver transplantation causes superior mesenteric vein circumfluence suffocate,and the small intestinal mucosa undergo congestion.After opening the blood flow,intestinal blood back to normal,and small intestine undergo reperfusion,which cause inevitable injury to intestine,leading to intestinal mucosa cells apoptosis、barrier function impaired and bacterial translocation.However,enterogenic infection after liver transplantation which is easy to cause systemic inflammatory response syndrome and even primary graft non function and multiple organ dysfunction syndrome is an important factor of blocking receptors and the increase of graft survival rate.Glucagon like peptide-2(GLP-2)is an intestinal epithelial growth factor,and its specific role is in gut.Studies suggest that GLP-2 can promote the growth of normal small intestinal mucosa,and enhance the intestinal barrier function,promote the repairing and healing of intestinal mucosa damage caused by intestinal inflammation.By promoting proliferation and inhibiting apoptosis of intestinal epithelial cell,GLP-2 can relieve intestinal ischemia/reperfusion injury and promote the recovery of transplanted small intestinal structure and absorption function.Studies about GLP-2 on the model of small intestine congestion reperfusion during liver transplantation have not seen.The purpose of this study is to explore the changes of small intestinal mucosa and mitochondria in the model of small intestinal congestion-reperfusion dealing with GLP-2,and explain the effect of GLP-2 in reducing congestion reperfusion injury of the small intestine and the role of mitochondria in the process of small intestinal injury and apoptosis,which provids new feasible method and theoretical support for the protection measures of the small intestine in the process of liver transplantation.Method40 healthy male C57BL/6 mice in total were used in this study.They were randomized into 8 groups:(1): normal control group(A);preconditioned groups,include(2): pretreatment with GLP-2 group(B1),(3): pretreatment with GLP-2 then undergo intestinal congestion-reperfusion group(B2),(4): pretreatment with PBS then undergo intestinal congestion-reperfusion group(B3);(5): pretreatment and treatment with GLP-2 and undergo intestinal congestion-reperfusion group(C);treatment groups,include(6): treatment with GLP-2 and undergo intestinal congestion-reperfusion group(D1),(7): treatment with PBS and undergo intestinal congestion-reperfusion group(D2);(8)intestinal congestion-reperfusion group(E).The animal model was constructed by clip-open superior mesenteric vein(i.e.small intestinal congestion-reperfusion injury)to simulate anhepatic phase during liver transplantation,and tissue was collected for detecting.The morphologic and the ultra-structural changes of small intestine under light microscope and transmission electron microscope were observed.We also detected the distribution of Ki67 in small intestinal crypts by immunohistochemistry and apoptosis in intestinal villus by TUNEL.In addition,we tested the expression of cleaved caspase-3 in small intestine tissue.Results(1)The morphologic and ultra-structural changes of small intestine in the model of small intestinal congestion-reperfusion: Compared with normal control group,we oberserved expanded central lacteals and cell vacuoles degeneration in intestinal congestion-reperfusion group.In contrast with normal control group,intestinal villus of pretreatment with PBS and then undergo intestinal congestion-reperfusion group were shorter and thicker,and central lacteals expanded.Other groups also had varying degrees of damage but were lighter than pretreatment with PBS and then undergo intestinal congestion-reperfusion group.The changes of ultrastructure were easy to see.Compared with normal control group,in pretreatment with PBS and then undergo intestinal congestion-reperfusion group and intestinal congestion-reperfusion group,we found nuclear chromatin pyknosis and edge accumulation.As to mitochondria,we saw obvious damage phenomenon like swelling、vacuolar degeneration、mitochondrial crest fracture or disappear in pretreatment with PBS and then undergo intestinal congestion-reperfusion group.Except for normal control group,mitochondria of other groups also had different degrees of damage.Compared with treatment with GLP-2 and undergo intestinal congestion-reperfusion group,the damage of mitochondria in treatment with PBS and undergo intestinal congestion-reperfusion group was more serious;in pretreatment with GLP-2 and then undergo intestinal congestion-reperfusion group and pretreatment and treatment with GLP-2 and undergo intestinal congestion-reperfusion group the damage of mitochondria was lighter,and pretreatment and treatment with GLP-2 and undergo intestinal congestion-reperfusion group was more obvious to see.(2)The distribution of Ki67 in small intestinal crypts: In groups dealed with GLP-2,we observed obviously expression of Ki67.Compared with groups pretreated or treated with PBS and undergo intestinal congestion-reperfusion,more expression of Ki67 in groups pretreated or treated with GLP-2 and undergo intestinal congestion-reperfusion were obeserved,while the pretreatment and treatment with GLP-2 and undergo intestinal congestion-reperfusion group was the most obvious to see.(3)The distribution of apoptosis in intestinal villus: Compared with Normal control group,obvious apoptosis existed in other groups and pretreatment with PBS and then undergo intestinal congestion-reperfusion group were most obvious.Compared with pretreatment with PBS and then undergo intestinal congestion-reperfusion group,apoptosis in pretreatment with GLP-2 and then undergo intestinal congestion-reperfusion group was markedly decreased.Compared with treatment with GLP-2 and undergo intestinal congestion-reperfusion group,apoptosis increased in treatment with PBS and undergo intestinal congestion-reperfusion group,although no statistical significance existed;apoptosis in pretreatment and treatment with GLP-2 and undergo intestinal congestion-reperfusion group decreased largely and had statistical significance when compared with above two groups.(4)The expression of cleaved caspase-3 in small intestine tissue: The expression of cleaved caspase-3 all increased except for normal control group,especially pretreatment with PBS and then undergo intestinal congestion-reperfusion group.Compared with pretreatment with PBS and undergo intestinal congestion-reperfusion group,expression of cleaved caspase-3 in pretreatment with GLP-2 and then undergo intestinal congestion-reperfusion group decreased markedly.Compared with treated with PBS and undergo intestinal congestion-reperfusion group,the expression of cleaved caspase-3 decreased in treatment with GLP-2 and undergo intestinal congestion-reperfusion group and pretreatment and treatment with GLP-2 and undergo intestinal congestion-reperfusion group.But,no statistical significance existed among them.Conclusion 1.GLP-2 reduces intestinal mucosa injury and promotes intestinal epithelial proliferation in the model of small intestinal congestion-reperfusion.2.GLP-2 decrease the apoptosis of injuried small intestine in the model of small intestinal congestion-reperfusion,and the process may be related to the mitochondria3.To relieve intestinal damage caused by liver transplantation,preoperative administration of GLP–2 is better than postoperative,while combined administration of GLP–2 is better than preoperative administration. |
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