实验性自身免疫性脑脊髓炎大鼠听神经损害研究

目的建立实验性自身免疫性脑脊髓炎(experimental autoimmune encephalomyelitis,EAE)大鼠模型,研究其脑干听觉诱发电位(brainstem auditory evoked potential,BAEP)Ⅰ波和听神经组织学改变。方法40只Wistar大鼠分为实验组和对照组,实验组(EAE组)用含卡介苗的豚鼠全脊髓匀浆为抗原免疫Wistar大鼠建立EAE动物模型,对照组用生理盐水混合完全福氏佐剂注射,采用诱发电位仪检测EAE组急性发病的大鼠和对照组大鼠的BAEP,通过透射电镜观察发病大鼠听神经外周段组织学改变。结果急性发病实验组大鼠BAEP的Ⅰ波潜伏期较对照组显著延长(P<0.01)。透射电镜下观察听神经外周段髓鞘松散,板层分离,局部变薄,呈不完全性脱髓鞘改变,轴突完整。对照组大鼠未见组织学改变。结论急性发病EAE大鼠听神经外周段脱髓鞘可能引起脑干听觉诱发电位Ⅰ波的改变。

The study on damage of acoustic nerve in experimental allergic encephalomyelitis (EAE) in rats

Objective To study the wave I of brainstem auditory evoked potential(BAEP) and morphological changes of the acoustic nerve in a rat model of allergic encephalomyelitis(EAE).Methods Forty Wistar rats were randomly divided into experimental and control groups.EAE model was created by injecting animals with guinea pig spinal cord homogenate(GPSCH) in complete Freund's adjuvant(CFA) Bacillus Calmette-GuerinVaccine(BCG) and control animals were injected with mixed Sodium Chloride and complete Freund's adjuvant(CFA).Brainstem auditory evoked potential was assayed at onset of symptoms.The pathological changes of the peripheral cochlear nerves were examined using transmission electron microscopy.Results In the BAEP study,the latencies of wave I were significantly prolonged in the EAE rats during the acute phase.Transmission electron microscopy revealed morphological features of incomplete demyelination in peripheral cochlear nerve including loose myelin,separation of myelin lamellae and local reduction in myelin thickness in the EAE rats.However,the axons were intact in the EAE rats.There were no significant changes in the myelin of the control animals.Conclusions Our study indicates that demyelination develops in the peripheral acoustic nerves of rats after EAE which may be responsible for the wave I of BAEP abnormalities during the acute phase.