重型颅脑损伤对小鼠小肠Cajal间质细胞与缝隙连接蛋白43影响的实验研究

Experiment study on effects of severe head injury on interstitial cells of Cajal and protein Cx43 in mice small intestine

目的通过观察重型颅脑损伤(SHI)后小鼠末端回肠离体肌条运动,肠肌丛Cajal间质细胞(ICC)数量和小肠组织缝隙连接蛋白43(Cx43)表达的变化,探讨SHI后肠动力障碍的可能机制。方法将36只8周龄清洁级健康雄性C57BL/6小鼠,按随机数字表法分为创伤组(参照Feeney自由落体法建立小鼠SHI模型)和对照组(仅开骨窗不打击),每组18只。于伤后3、7、14d取末端回肠,多通道生物信号采集与处理系统RM6280监测离体肌条自主收缩运动、激光共聚焦和Western blot检测ICC细胞数量及Cx43蛋白表达。结果创伤组伤后3d平滑肌收缩模式与对照组比较,差异有统计学意义(P<0.05),且收缩节律紊乱;7d时张力下降(P<0.05);14d时张力、频率与对照组比较,差异有统计学意义(P<0.05)。创伤组各时相点ICC细胞数量显著低于对照组(P<0.01),ICC分支变少且网络稀疏。创伤组Cx43表达量显著低于对照组(P<0.01)。结论小鼠SHI后肠道平滑肌自主收缩运动紊乱,ICC数量和Cx43表达的减少或缺失,可能是造成肠神经-ICC-平滑肌网络结构电信号传递障碍,引起肠道收缩模式紊乱,导致肠动力障碍发生的机制之一。

Objective To observe the change of isolated muscle movement,and interstitial cells of Cajal（ICC） and protein Cx43 in the small intestine after severe head injury（SHI）,and to study the possible mechanism of intestinal motility disturbance induced by SHI.Methods The model of SHI was built in 36 healthy adult C57BL/6 mice by the improved Feeney′ s weight-dropping method.The mice were randomly divided into the control group（opening skull but avoiding brain injury） and the trauma group,18 mice in each group.The in vitro terminal ileum smooth muscle strips were taken at the time points 3,7,14 d after SHI,and the spontaneous contraction movement,number of terminal ileum ICC and protein Cx43 expression were observed by the RM6280 system,the laser confocal microscopy and Western blot.Results Compared with the control group,the smooth muscle contraction amplitude was diminished,the contraction rhythm was irregular at 3d after SHI in the trauma group（P0.05）,the average tension was reduced at 7 d（P0.05）,the average tension and the contraction frequency were reduced significantly at 14 d（P0.05）.Compared with the control group,the number of ICC was significantly decreased at 3,7,14 d after SHI in the trauma group（P0.01）,and ICC showed fewer branches and sparse network.Compared with the control group,the protein expression of Cx43 after SHI in the trauma group was reduced significantly（P0.01）.Conclusion Spontaneous rhythmic contraction movement disorder of smooth muscle in small intestine emerges after SHI,the number of ICC and the expression of Cx43 are decreased or missed,which is one of the factors leading to electrical signals passing obstacles in network of enteric nerve-ICC-smooth muscle,causing intestinal contraction pattern disorder and resulting in intestinal motility disorder after SHI.