电针干预面神经损伤模型兔面神经核团中神经生长因子及其受体的表达

Effect of electroacupuncture on nerve growth factor and its receptor expression in facial nerve nucleus after facial nerve injury in rabbits

背景:研究发现周围性面神经损伤能引起神经生长因子表达变化,而电针穴位治疗对神经生长因子的影响机制尚不清楚。目的:通过建立兔周围性面神经损伤模型,予以电针刺激后,观察其对兔面瘫症状和面神经核团形态学的影响以及对神经生长因子及其受体表达的影响,探讨电针在周围性面神经损伤治疗中的作用机制。方法:将42只新西兰大白兔随机分为正常组(n=6)、模型组(n=18)、电针组(n=18)。正常组不做处理,其他2组兔建立右侧面神经上颊支压榨损伤模型。造模成功后,电针组每日取“合谷”穴埋针,“颊车”“地仓”“四白”“阳白”“翳风”“颧髎”6个穴位予以疏密波刺激;模型组不作治疗。电针治疗28 d采用苏木精-伊红染色观察面神经核团的形态学,免疫组织化学染色检测面神经核团中神经生长因子及其受体TrkA和p75NTR的表达部位及强度,并通过荧光定量PCR法检测面神经核团中神经生长因子及其受体mRNA的表达。实验经西南医科大学动物伦理学委员会批准,批准号为20170120001。结果与结论:①苏木精-伊红染色可见:电针组神经元术后形态恢复较模型组快且完全;②免疫组织化学染色显示:术后各时间点电针组神经生长因子的平均吸光度均高于模型组(P<0.05),电针组TrkA、p75NTR的平均吸光度在术后7,14,28 d均高于模型组(P<0.05);③荧光定量PCR检测结果显示:术后14,28天,电针组中神经生长因子和p75NTR mRNA相对表达量高于模型组;术后7,14,28天,电针组TrkA mRNA的相对表达量高于模型组(P<0.05);④结果提示:电针可以提高面神经核团中神经生长因子、TrkA、p75NTR的表达,并可能促进神经生长因子与TrkA和p75NTR的分别结合,这可能是电针在促进面神经损伤后修复的机制之一。

BACKGROUND:Preliminary studies have found that peripheral facial nerve injury can cause changes in the expression of nerve growth factor,but the mechanism of electroacupuncture in the expression of nerve growth factor is unclear.OBJECTIVE:Based on a model of peripheral facial nerve injury in rabbits,to observe the effects of electroacupuncture on facial paralysis symptoms,morphology of facial nerve nuclei and expression of nerve growth factor and its receptor and to explore the mechanism of electroacupuncture in the treatment of peripheral facial nerve injury.METHODS:Forty-two New Zealand white rabbits(n=66)were randomized into normal group(n=6),model group(n=30)and electroacupuncture group(n=30).A crushing injury model of superior buccal branch of the right facial nerve was established in the latter two groups.There was no deal with normal group.After successful modeling,a needle was imbedded at Hegu in the electroacpuncture group,followed by electric stimulations with dilatational wave at Jiache,Dicang,Sibai,Yangbai,Yifeng,and Quanliao.No treatment was done in the model group.At 28 days of electroacupuncture,morphological changes of facial nerve nuclei were observed using hematoxylin-eosin staining and the expression of nerve growth factor,TrkA and p75NTR in facial nerve nuclei was detected using immunohistochemical staining.The expression of nerve growth factor,TrkA and p75NTR mRNA was detected using fluorescent quantitative PCR.The study protocol was approved by the Animal Ethics Committee of Southwest Medical University,with an approval No.20170120001.RESULTS AND CONCLUSION:Hematoxylin-eosin staining results showed that the morphology of neurons recovered faster and more completely in the electroacupuncture group than the model group after surgery.The results of immunohistochemical staining showed that the average absorbance value of nerve growth factor in the electroacupuncture group was higher than that in the model group at every time point(P<0.05),and the average absorbance value of TrkA and p75NTR in the electroacupuncture group was higher than that in the model group on the 7^(th),14^(th),and 28^(th) days after surgery(P<0.05).Fluorescent quantitative PCR results revealed that the relative expression of nerve growth factor and p75NTR mRNA in the electroacupuncture group was higher than that in the model group on the 14^(th) and 28^(th) days after surgery(P<0.05).The TrkA mRNA expression in the electroacupuncure group was higher than that in the model group on the 7^(th),14^(th),and 28^(th) days after surgery(P<0.05).To conclude,electroacupuncture can improve the expression of nerve growth factor,TrkA,and p75NTR in facial nerve nuclei,and may promote the binding between nerve growth factor with TrkA and p75NTR,which may be the mechanism by which electroacupuncture promotes the repair of facial nerve injury.