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目的制作实验性自身免疫性脑脊髓炎(experimntalautoimmuneencephalomyelitis,EAE)动物模型,研究髓鞘蛋白脂质蛋白(proteolipidprotein,PLP)139-151多肽诱导的EAE大鼠听觉和听觉传导径路组织学改变,探讨其对大鼠听力的影响。方法动物分实验组和对照组,实验组大鼠用PLP139-151和含结核杆菌的完全福氏佐剂混合制成的抗原配剂行双侧后肢足垫下注射,制作EAE大鼠模型,对照组用生理盐水混合完全福氏佐剂注射。观察大鼠免疫前后体重变化和临床症状评分,检测EAE大鼠免疫前后听性脑干反应(auditorybrainstemresponse,ABR)、听神经复合动作电位(compoundactionpotential,CAP)、中潜伏期反应(middlelatencyresponse,MLR)及畸变产物耳声发射(distor-tionproductsotoacousticemissions,DPOAE)的变化,并利用电镜、免疫组织化学染色和Westernblot等方法观察EAE大鼠听神经及脑干组织学改变。结果免疫后EAE大鼠体重降低,症状评分在免疫后第14~21天达最高峰;ABR反应阈升高,ABR的波Ⅱ、Ⅴ潜伏期,Ⅰ-Ⅴ、Ⅱ-Ⅴ波间期和CAP的N2波潜伏期延长、波幅降低;MLR的Na、Pa潜伏期明显延长;DPOAE可正常引出,于免疫早期可见低频幅值升高;对照组听力学检测无明显改变。电镜下可见EAE大鼠听神经中枢端髓鞘松散、局部变薄或融合,免疫组织化学染色可见脑干白质局灶性脱髓鞘改变,可累及耳蜗核;Westernblot显示听神经PLP蛋白表达减少,髓鞘碱性蛋白(MBP)未见明显改变。结论EAE大鼠的病理改变主要浸润白质,可引起听觉中枢和听神经中枢端少突胶质细胞脱髓鞘,导致听觉中枢传导径路的听力学改变。
OBJECTIVE: To establish an experimental animal model of experimental autoimmune encephalomyelitis (EAE) and investigate the pathological changes of auditory and auditory pathways in EAE rats induced by proteolipid protein (PLP) 139-151 polypeptide Effect on rat hearing. Methods Animals were divided into experimental group and control group. Rats in experimental group were injected with footpad and injected with PLP139-151 and complete Freund’s adjuvant containing Mycobacterium tuberculosis to make EAE rat model. Group with normal saline mixed with Freund’s adjuvant injection. The changes of body weight and score of clinical symptoms before and after immunization were observed. The changes of auditory brainstem response (ABR), compound action potential (CAP), middlelatency response (MLR) and distortion products Otoacoustic emissions (DPOAE) were measured. The changes of auditory nerve and brainstem in EAE rats were observed by electron microscopy, immunohistochemical staining and Western blotting. Results The body weight of EAE rats decreased after immunization, and the symptom score reached the peak on the 14th to 21st days after immunization. The ABR threshold increased, the wave Ⅱ, Ⅴ latency, Ⅰ-Ⅴ, Ⅱ-Ⅴ wave interval and CAP The latency of N2 wave was prolonged and the amplitude was decreased. The latency of Na and Pa in MLR was prolonged obviously. DPOAE could be normally elicited, and the amplitude of low frequency increased in the early stage of immunization. There was no significant change in the control group. Electron microscope shows that the central nervous system of EAE rat is loose, local thinning or fusion of the central part of the myelin sheath. Immunohistochemical staining shows focal demyelination of white matter in the brainstem and can affect the cochlear nucleus. Western blot shows decreased expression of PLP protein in the auditory nerve, Alkaline protein (MBP) no significant change. Conclusion The pathological changes in EAE rats mainly infiltrated the white matter, which can cause the demyelination of the oligodendrocytes in the central auditory nerve and auditory nerve center, resulting in the audiological changes of the auditory central conduction pathway.