The induction of heme oxygenese-1 in intestinal mucosa of septic rat

背景：胆红素是一种生理性抗氧化剂。血红素氧合酶（HO）-1是血红素降解的限速酶，在肝、肾、脑中可被氧化应激诱导，但在肠中的诱导作用尚不清楚。方法：雄性Wistar大鼠腹腔注射大肠杆菌内毒素（LPS）10 mg/kg/体重。在0、1、3、5、7.5、10和24小时处死它们，收获它们的小肠粘膜。在肠粘膜中，测定还原型谷胱甘肽（GSH）、脂质过氧化物、HO-1 mRNA、HO-1蛋白、胆红素和胆红素氧化代谢产物（BOM）。结果：小肠GSH水平在3 ~ 5小时后显著下降，下降幅度为对照组的40%。脂质过氧化物水平在5小时时是对照水平的1.7倍。注射LPS后3 h，HO-1 mRNA水平增加至对照组的3倍，7.5h后HO-1蛋白表达增强。胆红素水平在10小时时增加至对照（峰值水平）的4倍，BOM在10小时时显示峰值水平的5倍增加。结论：脓毒症降低了GSH含量，增加了脂质过氧化物。这种肠道氧化应激诱导HO-1 mRNA的表达以及肠粘膜中蛋白质的产生。胆红素的产生和随后氧化为BOM表明胆红素起抗氧化剂的作用。这表明，在脓毒症中，小肠不仅是消化吸收器官，而且具有对氧化应激的快速反应能力。

Backgrounds : Bilirubin is known to be a physiological antioxidant. Heme oxygenase (HO)-1, the rate-limiting enzyme in the heme degradation, is known to be induced by oxidative stress in the liver, kidney, or brain, but its induction has not yet been known in the intestine, We studied the expression of HO-1 in intestinal mucosa induced by oxidative stress using a rat septic model. Methods : Male Wistar rats were given with lipopolysaccharide (LPS) from E.coli (10mg/kg/body weight) by peritoneal injection. They were killed at 0, 1, 3, 5, 7.5, 10 and 24 hrs and their small intestinal mucosa was harvested. In intestinal mucosa, reduced glutathione (GSH), lipid peroxide, HO-1 mRNA, HO-1 protein, bilirubin, and bilirubin oxidative metabolites (BOM) were measured. Results : Intestinal GSH level was significantly decreased after 3 to 5 hrs by 40% of the control level. Lipid peroxides level was 1 .7-folds of control level at 5 hrs. The level of HO-1 mRNA increased to 3 times of the control at 3 hrs and HO-1 protein was strongly detected 7.5 hrs after LPS injection. Bilirubin level increased to 4-folds of control (peak level) at 10 hrs and BOM showed 5-folds increase with the peak level at 10 hrs. Conclusions : Sepsis reduced the GSH content and increased lipid peroxides. This intestinal oxidative stress induced the expression of HO-1 mRNA as well as the production of the protein in the intestinal mucosa. Bilirubin production and subsequent oxidation to BOM indicates that bilirubin acted as an antioxidant. This suggested that small intestine had ability to respond quickly to oxidative stress in sepsis, not just as a digestive and absorptive organ.