| The pathogenesis of sever acute pancreatitis has not yet been fully elucidated, recent studies have shown that the excessive activation and release of inflammatory cytokines, leading to systemic inflammatory response syndrome (SIRS), are the core of the problem of SAP. In addition to the inflammatory cytokines, pancreatic microcirculation disorder is another important mechanism influencing the occurrence and development of SAP. Pancreas is different with other organs,it has unique microcirculation model , which makes it more likely ischemia and necrosis. Cyclooxygenase -2 (COX-2) can induce neutrophil adhesion and infiltration, start inflammatory response; mediate capillary injury, increase permeability, cause pancreatic microcirculation. Studies have confirmed that curcumin can reduce the inflammatory factor levels, reduce the pancreatic pathological damage, playing a protective role in SAP. At home and aborad, there was no report about curcumin on COX-2 and signal pathway of p38MAPK in the SAP model.Objective:This study examined the expression of COX-2 protein and the activity of p38MAPK signaling pathway in AHNP models and these models treat with curcumin. By studying the relationship between p-p38MAPK and COX-2 protein.We try to clarify the mechanism of the protective effects of curcumin on SAP.Methods:54 male Sprague-Dawley rats(200-250g weight)were randomly allocated into three groups:sham operated group(SO group); acute hemorrhagic necrotic pancreatitis(AHNP group); pretreatment with curcumin group (CUR group).each group was provided into three time points,each time point has six rats.The model of AHNP was induced by the retrograde injection of 5% sodium taurocholate in the pancreatic duct, 200mg curcumin per 1kg was injected intraperitoneally two hours prior to STC;but which was replaced dimethyl sulphoxide(DMSO)in SO and AHNP groups.Sham-operated animals was executed operation,but nothing was injected, pancreas was just flipped and striked gently a few times. Rats were killed by abdominal aorta exsanguination at 3h,6h and 12h after pancreatitis induced.The levels of serum amylase were measured, pancreatic tissue,pancreas was divided into two parts:one for immunohistochemistry (IMH) was fixed in 10%formalin, anther for western blotting was rapidly frozen in liquid nitrogen and then restored at-80℃.The activity of p38MAPK was tested by western blotting. we observed the effects of curcumin on serum amylase, pancreatic pathological change,expression of COX-2 protein and phosphorylation p38MAPK protein, further clarify the exact mechanism of anti-inflammatory effects of curcumin on SAP.RESULTS:1. Pancreatic macroscopic change: After Autopsy, no significant change in SO group; the glandular tissue became dull surface, edema, hemorrhage, and has a few of Saponification spots, bloody ascites in AHNP group. the degree of pancreatic damage in CUR group was lighter than AHNP group at the same time points.2. Pancreatic histologic score: SO group histopathological score was zero; AHNP group of three observation time points (3,6,12 h) scores were 4.40±0.19,5.63±0.47,6.65±0.73; CUR group of three observation time points scores were 3.92±1.13,4.37±0.48,5.05±1.14, the difference between AHNP group and CURgroup at 6h, 12h observation points was significant (P <0.05).3. Levels of serum amylase: At each observation time point, comparing with SO group, serum amylase was significantly increased in AHNP group (5472.00±2414.04,6330.70±2674.20,5606.80±1752.47) and CUR group (4959.50±1626.93,3645.20±1344.67,3656.70±788.3). and the difference was significant (P <0.05); at 6h, 12h two time points, the CUR group were statistically significant compared with AHNP (P <0.05).4. Expression of pancreatic COX-2 protein: SO group was found weak expression of COX-2, the pancreas acinar cells were stained yellow; AHNP group acinar cells were stained brown, the observation points were 8.45±0.68,8.78±1.31,10.10±1.22; CUR group acinar cells were stained yellow, the observation time points were 6.83±1.45,5.88±1.49,6.30±0.72. Three groups compared with each other,the differences are statistically significant (P <0.05).5. The activity of p38 MAPK: A small amount of protein expression was found in SO group;the AHNP group protein level was higher than SO group, the scores were 0.65 ±0.10,0.43±0.13,0.29±0.11 at the observation points, comparing with the SO group, the difference was significant (P <0.05); in CUR group,the scores were 0.45±0.12,0.30±0.08,0.22±0.04 at each observation time point ,comparing with AHNP group,the difference at 3h, 6h two observation time points were significant differences (P <0.05).6. Correlation analysis: In AHNP group and the CUR group, it was was positively correlated that pancreatic pathological damage compared with COX-2 protein expression (r = 0.699, p <0.01)and time (r = 0.585, p <0.01). p-p38MAPK and COX-2 was positively correlated at three time points in AHNP and CUR groups, and correlation coefficients were: 0.786,0.823,0.866 (p <0.01).Conclusions:(1) Curcumin can reduce the degree of pathological damage in pancreatic tissue of SAP in rats,suggesting that curcumin has a protective effect to SAP.(2) In severe acute pancreatitis, COX-2 and p-p38MAPK protein expression was more than nomal pancreas. Suggesting that COX-2 and p38MAPK signaling pathway involved in the early development of severe acute pancreatitis.(3) Curcumin treatment and untreatment groups showed an positive correlationship between p-p38MAPK and COX-2 protein expression, suggesting that curcumin reduced the expression of COX-2 protein by inhibiting p38MAPK/NF-κB pathway.
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