摘要
目的观察模拟高原环境暴露下大鼠肠黏膜屏障的损伤及谷氨酰胺(Gln)的保护作用,探讨高原肠黏膜屏障损伤与多器官功能障碍综合征(MODS)的关系。方法 30只SD大鼠按随机数字表法分为平原对照组(C组)、高原缺氧组(H组)和Gln保护组(HG组),每组10只。H和HG组动物在模拟海拔7000m的低压舱内生存72h,C组在平原环境下生存72h。观察各组大鼠小肠黏膜组织病理改变、肠上皮细胞凋亡、肠道细菌移位情况,并应用邻联二回香胺显色剂法检测血清和小肠黏膜二胺氧化酶(DAO)的活性,硫代巴比妥酸(TBA)法测定血清丙二醛(MDA)的含量,酶法测定血清超氧化物歧化酶(SOD)的活性和一氧化氮(NO)、Gln的含量。结果 H、HG组大鼠肠黏膜损伤严重,紧密连接间隙增宽,硝酸镧示踪法可见镧颗粒进入上皮细胞紧密连接间隙内以及基底膜外侧周围组织间隙或细胞内。H组肠系膜淋巴结和脾脏有细菌移位,移位细菌数为0.47±0.83CFU/g;HG组各器官移位细菌明显减少,细菌移位数为0.22±0.42CFU/g(P<0.05)。原位末端标记切口平移双标记法(TUNEL法)检测显示,H组肠上皮细胞凋亡细胞数增多,凋亡指数为16.2%±2.2%;与H组比较,HG组肠黏膜损伤明显减轻,肠上皮细胞凋亡细胞数明显减少,凋亡指数为13.3%±4.6%(P<0.05)。与C组血清内毒素(0.032±0.003kEU/L)、血清DAO(0.861±0.359kU/L)、血清Gln(3.083±0.186mmol/L),小肠DAO(0.516±0.062kU/L)、小肠Gln(0.573±0.032mmol/L)比较,H组血清内毒素(0.277±0.053kEU/L)和DAO(3.533±0.584kU/L)水平显著增高,血清Gln(1.472±0.079mmol/L)及小肠DAO(0.325±0.0533kU/L)、Gln(0.377±0.010mmol/L)水平显著降低(P<0.05或P<0.01);与H组比较,HG组血清内毒素(0.113±0.015kEU/L)和DAO(1.810±0.450kU/L)水平显著降低,血清Gln(1.951±0.070mmol/L)及小肠DAO(0.431±0.049kU/L)、Gln(0.448±0.021mmol/L)水平均显著增高(P<0.05)。结论高原缺氧能引起严重的肠黏膜屏障功能损伤,促进细菌和内毒素移位,引发全身炎症反应,是高原MODS发病的重要原因之一。Gln对高原肠黏膜损伤具有一定的保护作用,可降低肠黏膜通透性,减少细菌移位,减轻全身炎症反应。
Objective To investigate the relationship between high altitude gastrointestinal mucosal barrier injury and multiple organ dysfunction syndrome（MODS） by observing SD rats with damage of gastrointestinal mucosal barrier,and explore the protective effect of glutamine（Gln） under the simulated high altitude exposure environment.Methods Thirty adult male SD rats were randomly divided into plain control group（group C）,high altitude hypoxia group（group H） and Gln protection group（group HG）（10 each）.Rats in group H and group HG were allowed to live in a low-pressure chamber（simulated altitude 7000m） for 72 hours,and in group C in plain environment for a same period.Small intestinal mucosa tissue pathology,intestinal epithelium cell apoptosis and intestinal bacterial translocation were observed by light and electron microscopy.The diamine oxidase（DAO） activity in serum and small intestinal mucosa was detected with dianisidine developer,the serum malondialdehyde（MDA） content was detected with thiobarbituric acid（TBA） reagent,and the serum superoxide dismutase（SOD） activity,nitric oxide（NO） and glutamine（Gln） contents were detected with enzymatic method.Results The intestinal mucous had been seriously injured in group H and group HG,the junction gap widened,and the lanthanum nitrate tracing indicated that lanthanide entered into epithelial cells’ junction gap and the gaps or cells in peripheral basement membrane tissue.In H group,the bacterial translocation was observed in mesenteric lymph node（MLN） and spleen with translocation number of 0.47±0.83CFU/g;while the translocation number in HG group reduced to 0.22±0.42CFU/g（P〈0.05）.Under terminal deoxynucleotidyl transferase dUTP nick end labeling（TUNEL） observation,the apoptotic intestinal epithelial cells increased significantly with an apoptosis index of 16.2%±2.2%（P〈0.05） in H group,while the injury was abated obviously in HG group,with an apoptosis index of 13.3%±4.6%（P〈0.05）,since the Gln protection.Compared with the C group（serum endotoxin 0.032±0.003kEU/L,serum DAO 0.861±0.359kU/L,serum Gln 3.083±0.186mmol/L,small intestine DAO 0.516±0.062kU/L,small intestine Gln 0.573±0.032mmol/L）,the serum endotoxin（0.277±0.053kEU/L） and serum DAO（3.533±0.584kU/L） increased significantly,and serum Gln（1.472±0.079mmol/L）,intestinal DAO（0.325±0.053kU/L） and Gln（0.377±0.010mmol/L） decreased significantly in H group（P〈0.05 or P〈0.01）;Compared with H group,the levels of serum endotoxin（0.113±0.015kEU/L） and DAO（1.810±0.450kU/L） decreased significantly,serum Gln（1.951±0.070mmol/L）,small intestine DAO（0.431±0.049kU/L） and Gln（0.448±0.021mmol/L） increased obviously（P〈0.05） in HG group.Conclusions Hypoxia may induce severe primary intestinal barrier dysfunction,promote bacterial and endotoxic translocation,cause systemic inflammatory response,and is the major factor causing high altitude MODS.Gln may provide a protection against intestinal mucosa injury in high altitude,attenuate the intestinal mucosal permeability,and reduce bacterial translocation and systemic inflammatory response.
出处
《解放军医学杂志》
CAS
CSCD
北大核心
2011年第3期301-306,共6页
Medical Journal of Chinese People's Liberation Army
基金
军队“十一五”攻关课题(08G093)
国家科技支撑计划课题(2009BAI085B03)
关键词
高海拔
环境暴露
肠黏膜屏障
缺氧
谷氨酰胺
altitude
environmental exposure
intestinal mucosal barrier
anoxia
glutamine
