目的 本研究建立短肠后的肠适应代偿模型,对短肠综合征发生后剩余肠管的适应性形态和功能改变进行研究,为进一步深入了解短肠后剩余肠管的变化以及如何治疗提供理论依据。方法 将20只SD大鼠随机分成2组,一组为SBS大鼠模型组,即通过肠切除肠吻合手术制造SBS大鼠模型; 另一组为假手术组,即对照组。通过苏木精-伊红(HE)和AZAN胶原染色研究短肠综合征大鼠肠适应后肠管形态学的改变; 通过免疫组化实验研究短肠综合征后肠管神经元、神经纤维、ICC细胞、平滑肌细胞的改变; 通过器官浴槽实验研究乙酰胆碱诱导平滑肌肌条收缩功能的变化情况。结果 实验前两组大鼠体重无明显差异(t=0.890,P=0.382),术后1周,SBS组与对照组大鼠体重分别为(264.83±64.30)g和(319.50±42.89)g,两组差异有统计学意义(t=-2.292,P=0.033); 术后2周,SBS组与对照组大鼠体重分别为(317.71±63.50)g和(355.10±36.11)g,但两组差异有统计学意义(t=-1.672,P=0.109); 术后2周,SBS组大鼠吻合口近端肠管及远端肠管周长分别为(28.88±2.71)mm和(19.65±1.66)mm,对照组分别为(14.50±1.50)mm 和(15.10±3.10)mm,两组差异有统计学意义(t=15.346,P<0.001; t=4.006,P=0.002); 术后2周,SBS大鼠与对照组标记两点之间肠管长度分别为(56.19±2.97)mm 和(52.10±2.10)mm,两组差异有统计学意义(t=8.329,P<0.001); HE染色结果提示SBS组与对照组肠壁平滑肌层分别为(124.38±56.01)μm和(64.75±26.81)μm,两组差异有统计学意义(t=6.789,P<0.001); SBS组与对照组绒毛长度分别为(488.16±123.31)μm和(311.63±67.68)μm,两组差异有统计学意义(t=4.884,P<0.001); SBS组与对照组隐窝深度分别为(164.28±42.31)μm和(122.69±19.92)μm,两组差异有统计学意义(t=5.226,P<0.001)。AZAN染色结果提示SBS组的部分肌纤维被胶原替代。免疫组化结果提示短肠综合征大鼠增生肠管的肠神经系统中,神经元和神经纤维较对照组数量增多,ICC细胞减少,平滑肌肥厚明显; 器官浴槽实验提示在中低浓度(10-7mol/L,10-6 mol/L,10-5 mol/L)的乙酰胆碱刺激后,SBS组大鼠平滑肌活动的强度明显弱于对照组,两组差异有统计学意义(三组不同浓度的t值和P值依次为t=-3.465,P=0.001; t=-3.312,P=0.002; t=-2.080,P=0.042)。在高浓度时(10-4mol/l)两者差异无统计学意义(t=1.782,P=0.083)。结论 短肠综合征使得大鼠肠道平滑肌层的运动模式有所改变,其中神经元的数量增加,但对乙酰胆碱的反应减弱,ICC细胞数量减少,肌纤维被胶原蛋白替代。这一系列变化都是肠管结构和功能适应的结果。
Objective To investigate the contractile functions and Immunohistochemical characteristics of remnant ileum after intestinal adaptation in rats with short bowel syndrome. Methods The model of short bowel syndrome(SBS)was created by using surgical induction method.20 Sprague Dawley rats were divided into 2 groups in which they underwent intestinal resection and anastomosis or a sham surgery respectively.The morphological changes were observed by HE staining and AZAN staining; The variations of intestinal neurons,nerve fibers,ICC cells and smooth muscle cells were investigated by Immunohistochemistry.And the contractility of the ileum strips was measured by the organ-bath experiment. Results There was no significant difference in weight between the two groups before the experiment.1 week after the operation,the weight of the SBS group and the control group was(264.83±64.30)g and(319.50±42.89)g respectively,and there was a statistical difference between the two groups(t=-2.292,P=0.033).After 2 weeks of surgery,the weight of the SBS group and the control group was(317.71±63.50)g and(355.10±36.11)g respectively,but there was no statistical difference between the two groups(t=-1.672,P=0.109).2 weeks after surgery,the perimeter of the proximal bowel and the distal bowel of SBS group rats was(28.88±2.71)mm and(19.65±1.66)mm respectively,with the control group(14.50±1.50)mm and(15.10±3.10)mm,respectively,and there were statistical significance(t=15.346,P<0.001; t=4.006,P=0.002).2 weeks after surgery,the length of the intestinal tube between SBS rats and the control group was(56.19±2.97)mm and(52.10±2.10)mm respectively,and there was a statistical significance(t=8.329,P<0.001).HE staining results indicated that the smooth muscle layer of the intestinal wall of the SBS group and the control group was(124.38±56.01)μm and(64.75±26.81)μm,and there was a statistical difference between the two groups(t=6.789,P<0.001).The length of villi of SBS group and control group was(488.16±123.31)μm and(311.63±67.68)μm,and there was a statistical difference between the two groups( t=4.884,P<0.001).The crypt depth of SBS group and control group were(164.28±42.31)μm and(122.69±19.92)μm respectively,and there was a statistical difference between these two groups(t=5.226,P<0.001).The results of AZAN staining indicated that some muscle fibers in SBS group were replaced by collagen.The immunohistochemistry results indicated that the number of neurons and nerve fibers in the enteric nervous system of rats with the hyperplasia of the rats was more than that of the control group,and the ICC cells were decreased and the smooth muscle hypertrophy was obvious.Organ bath experiment hinted the strength of the SBS group of smooth muscle activity of rats significantly weaker than the control group at low concentration(10-7 mol/L,10-6 mol/L,10-5 mol/L)after acetylcholine stimulation,two groups had statistical significance(t value and P values of three groups of different concentrations of t=3.465,P=0.001; t=3.312,P=0.002; t=2.080,P=0.042).But at high concentration(10-4 mol/L),there was no statistical significance(t=1.782,P=0.083). Conclusion The circular muscle motility of SBS showed normal but weaker pattern,and SBS cause increased neurons but impaired response to parasympathetic stimuli.SBS also cause some cases with reduced distribution of ICC.SBS cause some cases of muscular changes and replaced by collagen.Both of the structure adaptation and function adaptation met the needs of metabolism and growth of the body,in that many of them could gradually recovered from intestinal failure.
