NF-κB活化及iNOS基因表达在急性胰腺炎肺损伤中的作用

Role of intrapulmonary expression of inducible nitric oxide synthase gene and nuclear factor-κB activation in lung injury in rats with acute necrotizing pancreatitis

目的 探讨急性坏死性胰腺炎 (ANP)大鼠肺组织核因子 κB (NF κB)活化及诱生型一氧化氮合酶 (iNOS)mRNA表达与肺损伤的关系。方法 33只Wistar大鼠随机分为正常对照空白组、盐水对照和胰腺炎组。以 3 5 %牛磺胆酸钠溶液逆行注入胰胆管制作ANP模型 ,并将N 乙酰半胱氨酸(NAC ;30 0mg/kg体重 )于造模前和后 1h用于ANP模型 ,造模后 12h取材 ,采用SP免疫组化方法检测肺组织NF κB活性。利用逆转录 聚合酶链反应 (RT PCR)法检测ANP肺组织iNOSmRNA表达 ,同时观察血淀粉酶、肺及胰腺组织湿 /干重比率、肺组织髓过氧化物酶 (MPO)及病理改变等。结果 正常对照组肺组织几乎无NF κB活化及iNOSmRNA的表达 ,ANP时肺组织NF κB活化及iN OSmRNA高表达 ,NAC对肺NF κB活性有抑制作用 ,可使肺iNOSmRNA表达降低 ,并可降低淀粉酶、胰腺组织湿 /干重比率及肺MPO。肺组织NF κB活化与iNOSmRNA表达及肺iNOSmRNA表达与MPO均呈正相关 ,相关系数分别为 0 79及 0 6 6 (P <0 0 1)。结论 肺组织NF κB活化及iNOSmRNA过度表达可能是ANP肺损害发生的原因之一。NAC可能通过抑制肺NF κB活性及iNOSmRNA的表达 ,减轻肺损害。

Objective To explore the relationship between intrapulmonary expression of inducible nitric oxide synthase (iNOS) mRNA,nuclear factor-κ B (NF-κ B) activation and pulmonary injury in rats with acute necrotizing pancreatitis (ANP). Methods Thirty-three Wistar rats were randomized into the normal group,normal saline solution group,ANP group and prophylactic and therapeutic groups with N-acetylcysteine (NAC). ANP was inflicted with 3.5% sodium taurocholate by the method of retrograde pancreatic injection. In the prophylactic group,rats received one intravenous injection of NAC (300 mg/kg) 1 h before taurocholate injection. In the therapeutic group,a similar dose of NAC was intravenously injected 1 h after taurocholate injection. All the animals were sacrificed in 12 h after induction of pancreatitis. Activation of NF-κB in pulmonary tissues was determined with immunohistochemistry. Intrapulmonary expression of iNOS mRNA was assayed by RT-PCR. Meanwhile,plasma level of amylase,pancreatic wet/dry weight ratio and histological grading,histological grading of lung injury and intrapulmonary content of myeloperoxidase (MPO) were determined. Results NF-κB binding activity was markedly increased after induction of pancreatitis. There were intrapulmonary overexpression of iNOS mRNA and elevation of intrapulmonary content of MPO. When NAC was given 1 h before induction of pancreatitis,the activation of NF-κB was prevented and plasma level of amylase,pancreatic wet/dry weight ratio and intrapulmonary content of MPO remarkably decreased. Intrapulmonary expression of iNOS mRNA had positive correlation with activation of NF-κB and intrapulmonary content of MPO (r=0.79 and 0.66,P<0.01). Conclusions The expression of iNOS mRNA and activation of NF-κB are associated with lung injury in ANP. Early blockage of NF-κB activation with NAC is effective for reducing severity of lung injury.