对灰鼠延迟性神经元死亡模型中螺旋神经节细胞缺损的评估

目的探索观察耳蜗螺旋神经节细胞的简便定量研究方法 ,并在灰鼠延迟性螺旋神经节细胞死亡动物模型中验证本方法的实用性和可靠性。方法 15只成年灰鼠平均分为3组,第1组用于正常对照;第2组一次性同时肌肉注射庆大霉素（125mg/kg）和静脉注射利尿酸钠（40mg/kg）,并在用药后2个月处死;第3组接受与第2组同样的药物注射,但在用药后4个月处死。耳蜗样品被常规应用环氧树脂包埋并制作成耳蜗中轴半薄切片,计数耳蜗各回蜗轴螺旋管腔切片截面内的螺旋神经节数量并进行统计分析。结果灰鼠耳蜗底回起始端的蜗轴螺旋管腔比耳蜗底回中部和耳蜗中回大,因此耳蜗底回起始端蜗轴螺旋管内的螺旋神经节细胞数量多于耳蜗底回中部和耳蜗中回。耳蜗毛细胞被彻底破坏后2个月,与正常灰鼠耳蜗各回蜗轴螺旋管腔切片截面内的螺旋神经节细胞数量相比,耳蜗底回蜗轴螺旋管切片截面内的螺旋神经节细胞减少数量比耳蜗中回严重,提示延迟性螺旋神经节细胞死亡可能遵循着从耳蜗底回向顶回扩展的规律。耳蜗毛细胞被彻底破坏后4个月,全耳蜗蜗轴螺旋管内的螺旋神经节细胞基本上丧失殆尽。结论计数耳蜗中轴切片各回蜗轴螺旋管腔切片截面内的螺旋神经节细胞数量是一种简便可靠的定量分析方法 。

Evaluation of spiral ganglion neuron missing in delayed neuron death model in chinchilla

Objective To seek a handy method to quantitatively evaluate the missing of spiral ganglion neurons in delayed neuron death model in chinchillas. Methods 15 adult chinchillas were divided averagely into three groups. Animals in group 1 were used as normal control. Animals in group 2 were sacrificed two months after co-administration of gentamicin （125 mg/kg） and ethacrynic acid （40 mg/kg）. Animals in group 3 were terminated four months after gentamicin and ethacrynic acid injection. The cochleae were routinely embedded in Epon-812 for cochlear sections. The number of spiral ganglion neurons in sections of Rosenthal＇s canal at various locations was counted and statistically analyzed. Results The size of Rosenthal＇s canal in cochlear hook region in chinchilla was bigger than that of the upper turns of the cochlea that containing more spiral ganglion neurons in the base. Two months after the cochlear hair cell removal,more spiral ganglion neurons missing was found in the hook. This suggested that the delayed spiral ganglion neuron missing might develops from the base of the cochlea with gradient towards apex. Four months after co-administration of gentamicin and ethacrynic acid,most spiral ganglions disappeared due to lacking neuronotrophins. Conclusion Evaluation of cochlear spiral ganglion neurons in sections at Rosenthal＇s canal at different locations is a reliable approach to quantitative observations.