Role Of Pi3K∕PKB Signal Pathway And The Specific Inhibitor Wortmannin In Intestinal Injuries Induced By Acute Pancreatitis In Rats

Acute pancreatitis (AP) is one of the most frequent clinical acute abdominal, in addition to pancreatic lesions, often complicated with multiple-organ dysfunction syndrome(MODS), intestinal injury is one of the most important complications. When intestinal mucosa damage, lots of endotoxin, bacteria are released into the blood, cause endotoxemia or bacteremia, aggravating systemic inflammation, even causing MODS. Therefore, the actively prevention and treatment of intestinal damage has become important influence factors of AP. Intestinal injury mainly performance for dyskinesis, the damage of dilated bowel and mucous membrane barrier function, the mechanism mainly with inflammatory cells infiltrating loops, the releasing of inflammatory mediators-tumor necrosis factor (TNF alpha)and cytokines, oxygen-free radicals and bacteria excessive breeding in intestinal canal. Phosphatidylinositol 3-kinase(PI3K) is a second messenger that is related to intracellular signal transduction. Protein kinase B(PKB) is a downstream effector of PI3K. PI3K∕PKB signal pathway is an important signal system which causes celluar response through mediating extracelluar signaling. It plays important roles in the following fields: activation and chemotaxis of inflammatory factors, cancer progression, ischemia-reperfusion, interstitial fibrosis and so on. Recently, the relationship between PI3K∕PKB signal pathway and pancreatitis obtain more and more attention. When PI3K∕PKB signal pathway is activated in pancreatitis, its products can activate the downstream factors. These activated downstream factors can recruit neutrophil to produce inflammatory factors and lead to cascaded amplification, which called"cytokine storm". Mutiple organs are damaged in the reactions. By increasing the intra-cellular Ca2+ level, PI3K can activate trypsinogen and promote the development of pancreatitis. Normally, phosphorylated P-PKB can measure the activation of PI3K∕PKB signal pathway. In our test, the expressional levels of P-PKB and PKB in intestine were measured ,which is used to study the relationship between PI3K∕PKB signal pathway and intestinal injuries induced by AP in rat. Our study use the specific inhibitor of PI3K wortmannin to interfere in intestinal injuries induced by AP and investigate its possible mechanism.Objective: To investigate the role of wortmannin in intestinal injuries induced by acute pancreatitis in rats and its mechanism.Methods: Fifty-four healthy male SD rats were randomly divided into 3 groups: SO group(sham operation group), AP group (acute pancreatitis group),WAP group(acute pancreatitis plus wortmannin).(n=18 per group). AP modle was induced by retrograde injection of 50g/L sodium taurocholate into the biliopancreatic duct of rats. wortmannin was administered to WAP group introperitoneally with the dosage of 0.35mg/kg 4 hours before the modle was made. The serum levels of amylase, tumor necrosis factor-alpha ( TNF-α), endotoxin were measured; myeloperoxidase (MPO) activity in intestine was minitored; the expressional levels of PKB and P- PKB were measured by western blot; intestine and pancreas were collected to examine pathological changes.Results: The serum levels of tumor necrosis factor-alpha ( TNF-α), amylase, endotoxin and myeloperoxidase (MPO) activity in intestine of AP group were significantly elevated ( P < 0. 05) compared with SO group. The pathological changes in intestine and pancreas were worsened as time prolonging; all indices in WAP group were significantly elevated ( P < 0. 05) compared with SO group and significantly decreased ( P < 0. 05) compared with AP group. There is no significant difference of PKB expression among the 3 groups. The P-PKB expression in AP group and WAP group was significantly elevated ( P < 0. 05) compared with SO group, and the P-PKB expression in WAP group was significantly decreased ( P < 0. 05) compared with AP group . Conclusions: PI3K∕PKB signal transduction pathway is involved in the pathogenesis of intestine injuries induced by acute pancreatitis in rats, pretreatment with wortmannin can inhibit the PI3K∕PKB signal transduction pathway, thus relieving the intestinal injuries induced by acute pancreatitis. The mechanism is related to the inhibition of activation and chemotaxis of inflammatory factors and neutrophil aggregation.