【作者】 单信芝；

【导师】 马爱国； 韩磊；

【作者基本信息】 青岛大学 ， 营养与食品卫生学， 2009， 硕士

【摘要】 目的:本研究通过建立急性放射性肠炎大鼠模型,研究β-胡萝卜素(beta-carotene)对急性放射性肠炎大鼠小肠黏膜功能保护作用的影响,并探讨其可能的作用机制。方法:1.动物分组及模型建立:健康成年雌性Sprague-Dawley远交群大鼠(SD)40只,采用随机数字表进行分组,分别为:空白对照组(C组)、单纯照射组(R组)、β-胡萝卜素5mg/(kg·d)组(T1组)、β-胡萝卜素10mg/(kg·d)组(T2组)。每组10只。T1组、T2组均按2.5ml/kg灌胃β-胡萝卜素油剂,C组、R组灌胃等量花生油,连续灌胃14天,第15天R、T1、T2组以直线加速器用9Gy照射剂量自剑突下至肛门进行全腹一次性照射。照射后第4天处死大鼠,处死前12h以0.5g/kg剂量灌胃D-木糖,收集12h尿液。2.一般状况的观察:照射后观察大鼠大便性状、进食情况、精神状态和体重的变化。3.肠黏膜形态学评价:屈氏韧带下8-10cm取长度2cm左右的空肠,制作石蜡切片,光镜下观察绒毛和腺体损伤程度。用计算机图像分析仪分别测定绒毛隐窝轴(theCrypt-Villus Axis,CVA)长度。4.肠黏膜屏障功能评价:分别测定血清肿瘤坏死因子-α(TNF-α)浓度、黏膜TNF-α浓度、血浆内毒素浓度和二胺氧化酶(DAO)活性。5.肠黏膜吸收功能评价:采用还原法测定尿D-木糖排出量。结果:1.单纯照射组大鼠出现稀薄的粘液便,潜血实验阳性。补充β-胡萝卜素5mg/(kg·d)组和10mg/(kg·d)组大鼠出现粘液便,潜血实验阴性。2.灌胃结束时,各组大鼠体重无显著性差异,p＞0.05。处死前,空白对照组(C组)、单纯照射组(R组)、β-胡萝卜素5mg/(kg.d)组(T1组)、β-胡萝卜素10mg/(kg·d)组(T2组)大鼠体重分别为227.48±3.60g、218.77±3.42g、221.71±2.54g、224.32±2.37g,R组、T1组与C组比较有显著性差异,p＜0.05;T2组与C组比较无显著性差异,p＞0.05。自照射开始至处死大鼠时,C组、R组、T1组、T2组大鼠体重分别增长了2.48±0.75g、-4.96±2.79g、-1.05±0.91g、-0.20±1.29g,R组、T1组、T2组与C组比较有显著性差异,p＜0.05;T1组、T2组与R组比较有显著性差异,p＜0.05。实验初至实验末大鼠体重均出现了不同程度的增长,C组、R组、T1组、T2组分别增长了14.98±0.94g、7.16±3.23g、10.61±1.21 g、12.6l±1.01g,R组、T1组与C组比较有显著性差异,p＜0.05;T2组与C组比较无显著性差异,p＞0.05。C组、T2组与R组比较有显著性差异,p＜0.05;T2组与T1组比较具有显著性差异,p＜0.05。3.单纯照射组大鼠肠腔明显扩张、充血,小肠绒毛出现水肿、坏死、脱落,与固有层分离,固有层可见大片的以淋巴细胞为主的炎性细胞浸润。补充β-胡萝卜素5mg/(kg·d)组肠腔无明显扩张、充血,有轻度水肿,黏膜结构相对完整,局部可见以淋巴细胞为主的炎性细胞浸润。补充β-胡萝卜素10mg/(kg-d)组肠腔无扩张、充血,黏膜结构完整。与空白对照组比较,单纯照射组、补充β-胡萝卜素5mg/(kg·d)组绒毛隐窝轴长度变短,黏膜损伤明显,有显著性差异;补充β-胡萝卜素10mg/(kg·d)组绒毛隐窝轴长度无明显改变,黏膜损伤轻微,无显著性差异。4.与空白对照组比较,补充β-胡萝卜素10mg/(kg·d)组血浆内毒素、血清TNF-α浓度、黏膜TNF-α浓度无明显升高,p＞0.05。补充β-胡萝卜素5mg/(kg·d)组和单纯照射组血浆内毒素、血清TNF-α浓度、黏膜TNF-α浓度明显升高,有显著性差异,p＜0.05。5.各组血浆DAO含量差异无统计学意义,p＞0.05。6.空白对照组、单纯照射组、β-胡萝卜素5mg/(kg·d)组、β-胡萝卜素10mg/(kg·d)组大鼠12h尿液D-木糖排出量分别为:148.03±39.78mg、25.54±7.66mg、59.89±13.07mg、95.33±20.29mg。β-胡萝卜素10mg/(kg·d)组与空白对照组比较无显著性差异,p＞0.05。单纯照射组和补充β-胡萝卜素5mg/(kg·d)组与空白对照组比较有显著性差异,p＜0.05。结论:1.用直线加速器以9Gy照射剂量从剑突下至肛门进行全腹一次性照射可以建立稳定的急性放射性肠炎大鼠模型。2.β-胡萝卜素10mg/(kg·d)剂量补充可以减轻X线辐照对大鼠小肠黏膜绒毛的损伤,减少黏膜和黏膜下的炎症反应,减轻大鼠腹部辐射损伤后的消化道症状,抑制TNF-α的表达,减轻炎症性反应,在一定程度上可维持肠黏膜屏障功能。3.一定剂量的β-胡萝卜素通过减轻X线对肠黏膜的损害,增加肠黏膜对D-木糖的吸收,维护肠黏膜的吸收功能。更多还原

【Abstract】 Effects ofβ-carotene on the small intestine mucosal barrier and the absorption function of acute X-ray caused abdominal injury ratsAbstract Objective To investigate effects ofβ-carotene on the barrier and absorption function of acute X-ray caused abdominal injury rats.Method:40 female SD rats were randomly divided into 4 groups:Group C was the blank control group.Group R was the radiation group that accepted only X-ray radiation.Group T1 acceptedβ-carotene 5mg/ kg-d,and group T2 acceptedβ-carotene10mg/kg·d.After 14 days of continuous administration of peanut oil in groups C and R or beta-carotene（2.5ml/kg） in groups T1 and T2,the rats were radiated under X-ray of a 9 Gy dose.Then the rats were fed 0.5g/kg D-xylose orally at the 3^rd day of the radiation.The 12 hours’urine was collected to test the content of D-xylose.3 days later,the rats were killed and the amount of diamine oxidase（DAO） and the level of bacterial endotoxin and TNF-αwere detected.The structure and length of the crypt-villus axis（CVA） and TNF-αof jejunum mucosa were also observed and analyzed.Resμlts Obvious damaged structures of jejunum were observed in group R,including villus adema,necrosis,and the focal exfoliation of the epithelial cell.Damage of jejunum in groups T1 and T2 were relatively minor compared to group R with less adema,necrosis,et al.CVA length of group T2 was significantly longer than those of groups R and T1（p＜0.05）.Furthermore,the level of endotoxin and TNF in blood and gut mucosa were lower than those of groups R and T1（p＜0.05）.The content of D-xylose in urine was higer than those in groups R and T1（p＜0.05）.But there was no significant difference in amount of DAO among all the groups（p＞0.05）. Conclusions Beta-carotene may decrease the X-ray radiation damage on jejunum and maintain the normal function of gut mucosa barrier damaged by X-ray radiation in rats.更多还原