Protective Effects Of Exogenous Leptin On Liver Injury Induced By Acute Pancreatitis In Rats

Objective：We observed the effects of the exogenous leptin onthe apoptotic index of liver cell, the expression of NF-κB, and the serum tumornecrosis factor-a (TNF-α）, Alanine aminotransferase (ALT), aminotransferaseaspartate (AST), serum amylase level of amylase(AMY) in rats with severeacute pancreatitis(SAP), in order to investigate the protective effect andmechanism of Leptin on liver injury induced by acute pancreatitis in rats.Methods:30male SD rats, weighting250g-300g, were randomly divided intothree groups: sham operation group, severe acute pancreatitis model group(SAP group), leptin treatment for severe acute pancreatitis group (leptin group).The rat’s abdomen of the sham operation group was opened, slightly moved theduodenum and pancreas, and then sutured the cut. The models of SAP groupand leptin group were induced by retrograde infusion of3.5%sodiumtaurocholate (1ml/kg,0.2ml/min speed) into the biliopancreatic duct. After themodel was successfully established, leptin was administered to the rats of leptingroup by intraperitoneal injection at a dose of20ug/kg, and equivalent volumeof normal saline (NS) was given by tail intravenous injection to the SAP groupsand sham operation group. After fasting, drinking freely. The rats weresacrificed at12h after modeling. We observed the pancreas and liver tissue ofthe rats in each group, and assessed the pathologic grading usinghematoxylin-eosin (HE) staining. The expression of NF-κB in liver tissue wasdetected by immunohistochemical staining. Serum ALT, AST, AMY from theinferior vena cava was measured by an automated biochemistry analyzer. SerumTNF-α levels was assayed by enzyme-linked immunosorbent assay (ELISA).The apoptosis index of liver tissue was assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling, and the expression of NF-κB p65was tested by immunohistochemical staining. All the above results wereanalyzed using SPSS12.0software. Results:1. Death of the rats, there was notrat dead in sham operation group, but three rats dead in SAP group, one rat deadin Leptin group at12h.2. Intraperitoneal appearance change of eachexperimental group: there were not ascites in the peritoneal cavity and visiblepathological changes of pancreas and liver, meanwhile, tissue peritoneal cavitywithout saponification plaque formation, intestinal cavity without pneumatosisin Sham operation group. Pancreatic tissue in SAP group presented extremeedema of gray color, the decrease of tissue elasticity, extensive adhesion withsurrounding tissue, the pancreatic tissue necrosis, hemorrhage around thepancreas and abdominal fat necrosis, and a lot of saponification spot. Livercapsular tension increased, the volume slightly enlarged, the surface is dark red,which was adhesion to the pancreatic tissue with visible petechial hemorrhageon subcapsular region. Increased the hepatic tissue became fragile and easy torupture. There were more yellowish ascites in the peritoneal cavity, andextensive intestinal cavity pneumatosis was more visible. The dilatation of thestomach caused the gastric contents retention, and the posterior abdominal wallwas visible mesentery and being with more saponification plaque attached.Pancreatic tissue in leptin group was gray with adhesion to the surroundingtissue and a small amount of bleeding. Compared to the SAP group, surroundingfat tissue necrosis decreased significantly, pancreatic peripheral saponificationplaque was reduced, and saponification plaque of mesenteric and celiac wasinvisible. The volume of liver tissue did not change significantly, and the colorwas dark red, uniform, no bleeding, no adhered to pancreatic tissue. A smallamount of yellowish ascites in the peritoneal cavity and partial intestinal cavitypneumatosis were visible.3. Each experimental group pancreatic changes underlight microscope: sham operation group, pancreatic tissue under light microscope, HE staining under light microscope pancreatic tissue structuralintegrity. There were not edemas, bleeding, and inflammatory cell infiltration inpancreatic tissue. The SAP group showed pancreatic tissue of leaf interval,interlobular septa and pancreatic acinar interval widen, pancreatic acinar cellswelling, and inflammatory cell infiltration in pancreatic acinar interval,pancreatic tissue hemorrhage, extensive necrosis, pancreatic lobule structuredisappeared. Partial necrosis was calcification. Leptin group visible part ofpancreatic lobular structure disorder, infiltration of inflammatory cells in theinterstitial, pancreatic acinar cell swelling, and showed different degree ofpancreatic tissue hemorrhage, necrosis and other pathological change, but thedegree of necrosis, hemorrhage and inflammatory cell infiltration were milderthan those in SAP group.4. Changes of liver pathology: sham operation groupliver tissue and liver cells were arranged regularly, and there were no edema, nocell gap widened, and no cell necrosis and apoptosis. The SAP group showedliver cell edema, intercellular space widened, see more eosinophilicdegeneration of cells, the cells showed spotty necrosis, interstitial visible redblood cells, hepatic sinusoids and periportal visible more amount ofinflammatory cell infiltration and packed red cells. In SAP group, mild edemaof liver cells, cell gap widened, a small amount of eosinophilic cells wasinvisible, but no significant liver necrosis, hepatic sinusoids and periportalinflammation cells were significantly decreased compared with that in SAPgroup. The organization did not see red cells.5. Liver cell apoptosis index,expression of NF-κB in liver tissue of group SAP and leptin were higher thanthose in the sham operation group (P<0.05), leptin group compared with theSAP group decreased (P<0.05). Leptin group compared with SAP group, serumAMY, AST, ALT, TNF-α detection levels decreased (P<0.05), SAP groupincreased compared with the sham operation group (P<0.05). Conclusion:1.The protective effect of exogenous leptin on liver injury induced by acute pancreatitis can inhibit the inflammatory reaction, reduce the severity of livercell apoptosis, may provide a new way for the clinical treatment of severe acutepancreatitis complicated with liver injury.2. TNF-α has played an important rolein the occurrence and progression of a evolution process of liver injury inducedby severe acute pancreatitis in individual. We could reduce tissue damage causedby inflammation through inhibits TNF-α.3, Liver cell apoptosis played animportant role in liver injury induced by SAP，reduce the severity of liver cellapoptosis through inhibiting the expression of NF-κB, so as to protect the liver.