| Objective: By establishing severe acute pancreatitis(SAP) model in Sprague-Dawley rats, we observe the pathology changes of pancreas and intestinal, the expression of COX-2 in the intestinal mucosa, the serum levels of inflammatory mediators such as TNF-α,TXA2,PGI2. In our study, we expect to investigate the relation between COX-2 with associated inflammatory mediators and SAP associated gut barrier injury. Further, we aim to investigate the effect of selective cyclooxygenase-2 inhibitor(Celecoxib) on SAP associated gut barrier injury and explore the mechanism.Methods: Seventy-two adult male Sprague-Dawley rats weighting 300-340g were randomly divided into three groups: control group(group C), severe acute pancreatitis group(group SAP) and treatment group with Celecoxib(group T). Each group was randomly divided into three subgroups as the phases of 3h,6h,12h after operation. Rats in group SAP were induced by the retrograde injection of bilio-pancreatic duct with 5% sodium taurocholate(1.0ml/kg), but rats in group C , 5% sodium taurocholate was displaced by 0.9% sodium chloride. In group T, Celecoxib(30mg/kg) was administrated affusedly down alimentary canal from mouth to stomach at 2 hours before the inducement of SAP. Rats were killed after observed on schedule. The blood samples and the tissues samples including mesentery lymph nodes, liver, kidney, lung, pancreas and terminal ileum were harvested. The level of serum AMS was detected by iodine-amylum colorimetric method, while the serum level of TNF-αby ELISA. Serum endotoxin was determined by chromogenic end-point tachypleus amebocyte lysate. Serum levels of TXB2 and 6-keto-PGF1αwere detected by radioimmunoassay. The bacterial culture of samples from mesentery lymph nodes, liver, kidney, lung, pancreas were made respectively. The pancreas and ileum samples were processed for microscopic histologic lesion score. Expression of COX-2 and NF-κB in ileum tissues were determined by immunohistochemical technique.Results: 1. In comparison with group C, the serum levels of AMS, TNF-α, ET, TXB2, 6-keto-PGF1αand the ratio of TXB2/6-keto-PGF1αwere significantly increased in group SAP(P<0.01). Compared with group C, the bacterial translocation rate of tissues and the pathological scores of pancreas and ileum tissue injury were markedly increased in group SAP(P<0.01). 2. Expression of COX-2 in ileum tissues in group C was almost not detected, but overexpression of COX-2 could be observed in group SAP. Expression of NF-κB in intact ileum tissues was almost not detected, but overexpression could be observed in group SAP, and overexpression of NF-κB reach peak in 3 hours after sodium taurocholate induction. 3. There was positive correlation between the serum level of endotoxin and pathological scores of ileum injury(rs=0.874,P<0.01), the same as the expression of COX-2 in ileum tissues (rs=0.859,P<0.01). There was positive correlation between the ratio of TXB2/6-keto-PGF1αand the expression of COX-2 in ileum tissues (rs=0.886,P<0.01). In addition to, the expression of COX-2 in ileum was positively correlated with the serum level of TNF-α(rs=0.902,P<0.01). 4. In comparison with group SAP, the serum levels of AMS, TNF-α, ET, TXB2 and the ratio of TXB2/6-keto-PGF1αwere significantly decreased in group T(P<0.05). Compared with group SAP, the bacterial translocation rate of organs and the pathological scores of pancreas and ileum tissues injury were markedly decreased in group T(P<0.05), while expression of COX-2 and NF-κB in ileum tissues was significantly down-regulated in group T (P<0.05).Conclusions: 1. The gut barrier in rats is damaged in the early phase of SAP, which results in bacterial translocation and intestinal endotoxemia. 2. The expression of COX-2 and NF-κB in ileum tissues in rats is significantly up-regulated in the early phase of SAP. 3. Celecoxib can relieve gut barrier injury in experimental SAP. There are some possible mechanisms: one can be inferred that Celecoxib may inhibit TNF-αproduction and down-regulate the expression of COX-2 and NF-κB so as to alleviate systemic inflammatory response ; another can be deduced that Celeeoxib may decrease the level of TXB2 and 6-keto-PGF1αand correct the imbalance between TXB2 and 6-keto-PGF1αto improve microcirculation disturbance in pancreas and ileum tissues.
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