Protective Effect Of MG-132 And Its Mechanism In Rats With Acute Pancreatitis

Objectives: This study was aim to study the protective effect of the proteasome inhibitor MG-132 in rats of acute pancreatitis established with retrograde injection of 3.5% sodium taurocholate into the biliary-pancreatic duct and to explore its possible mechanisms.Methods:1 Experimental model of acute pancreatitis A totally 30 healthy and clean male SD rats, weight 150 + 20 g, were randomly divided into the control group(C)(n=10), the acute pancreatitis group(A)(n=10) and the MG-132 treatment group(T)(n=10). Experimental model of acute pancreatitis was made by retrograde injection of 3.5% sodium taurocholate(1ml/kg) into the biliary-pancreatic duct with the speed of 0.2 m L/min. The control group was treated by the same operation mode, but not for the injection of sodium taurocholate instead of turning the pancreas and duodenum gently. The MG-132 treatment group were injected MG-132(0.25 ml two 10mg/kg dissolved in DMSO) intraperitoneally at 30 minutes before making modes. The acute pancreatitis group and control group were injected the 0.25 ml DMSO intraperitoneally at the same time point. All rats after operation were fasted, but could drink. The 2ml blood samples of rats in each group were collected at 6h after operation though heart cavity puncture and operated centrifugal by 3000r/min in 15 min and stored in a refrigerator at-80℃.Then quickly cuted the pancreas tissue and fixed with 10% formalin solution immediately.2 The level of serum amylase was measured by colorimetric method.3 The level of interleukin-6(IL-6) was measured by ELISA method.4 The expressions of Monocyte chemoattractant protein-1(MCP-1) and macrophage inflammatory protein-2(MIP-2) in pancreatic tissue were determined by Westen-blot method.5 Pancreas tissue of rats were changes by HE staining and the evaluation of pancreas pathology was according to Schmidt’s method.6 The activity of NF-κB was determined by immunohistochemistry and applied the immunohistochemistry score.7 The data were analyzed by SPSS 18.0,the levels of amylase、IL-6、MCP-1and MIP-2 serum used SNK method of analysis of variance. The immunohistochemistry score and the pathology score used Kruskal-Wallis H test. P<0.05 means there were statistical significance in these groups.Results:1 The level of serum amylase: The level of serum amylase in the control group was 158.04±0.91U/L;the level of serum amylase in the acute pancreatitis group was 634.38±3.07U/L; the level of serum amylase in the MG-132 of treatment group was 396.03±1.74U/L. The level of serum amylase in the acute pancreatitis group and MG-132 treatment group were higher than that in the control group(P <0.05).And the level of serum amylase in the treatment group was lower than that in the acute pancreatitis group(P<0.05).2 The level of IL-6: The level of IL-6 in the control group was 3.52±1.94U/L; the level of IL-6 in the acute pancreatitis group was 14.97±2.89U/L; the level of IL-6 in the MG-132 treatment group was 6.04±2.73U/L. Compared with the control group, the level of IL-6 of in treatment group was lower than in the acute pancreatitis group(P<0.05).3 The expression level of MCP-1 and MIP-2: The expression level of MCP-1 and MIP-2 in the control group were 0.23±0.10U/L and 0.27±0.08U/L respectively; the expression level of MCP-1 and MIP-2 in the acute pancreatitis group were 0.59± 0.10U/L and 0.56± 0.12U/L respectively; the expression level of MCP-1 and MIP-2 in the MG-132 treatment group were 0.38±0.07U/L and 0.43±0.10U/L respectively. The expression level of MCP-1 and MIP-2 in the acute pancreatitis group and MG-132 treatment group were significantly higher than that in the control group(P<0.05). Compared with the acute pancreatitis group, the expression level of MCP-1 and MIP-2 in treatment group were lower(P<0.05).4 Gross specimen of pancreatic tissues: there were nearly no hyperemia, edema and effusion in the control group; the acute pancreatitis group showed the pancreas congestion, edema and little ascites in abdomen; the MG-132 treatment group showed less congestion, edema in pancreas, and there were nearly no ascites in abdomen.5 Pancreas pathology score: the pancreas pathology score of the control group was 0 score and there was no hyperemia, edema or inflammatory cells infiltration; The acute pancreas group showed a widen pancreatic lobules gaps, acinar edema, patchy necrosis and a large number of inflammatory cells infiltration and the pathology score was 8.21±1.73 scores; there were less hyperemia, edema and inflammatory in the MG-132 treatment group than that in the acute pancreatitis group and the pathology score was 4.63±0.86 scores. The pathology score in this three groups had significantly differences(P<0.05).6 Immunohistochemistry demonstration: the expression of NF-κB of pancreatic tissue in the control group showed a small amount, and the immunohistochemistry score was 2.10±0.99 scores; NF-κB in the acute pancreatitis group expressed strongly and the immunohistochemistry score was 7.70±2.95 scores; the expression of NF-κB of pancreatic tissue in the MG-132 treatment group, the immunohistochemistry score of which was 4.20±2.25 scores, was less than that in the acute pancreatitis group,but it was more than that in the control group significantly. Compared with the control group, the immunohistochemistry score of the MG-132 treatment group and acute pancreatitis group had significant difference(P<0.05).Conclusions:1 The levels of IL-6 and the expression of MCP-1、MIP-2 and NF-κB were significantly increased which played an important role in the pathogenesis of acute pancreatitis.2 This study suggested that proteasome inhibitor MG-132 played a protective role in acute pancreatitis of rats. The protective mechanism may be related to the inhibition of NF-κB, so as to control the inflammatory reaction.