耳蜗毁损后小鼠听觉中枢的退行性改变

目的 观察双侧耳蜗损毁对小鼠听觉中枢蜗神经核群的影响.方法 40只健康成年BABL/c小鼠,随机数字表法分为对照组和实验组,每组20只.实验组小鼠在解剖显微镜下切除鼓室后壁,损毁双侧耳蜗.手术后第2天与4个月时进行听性脑干反应(ABB)测试.术后4个月处死小鼠,取脑组织进行脑干连续切片,通过尼氏染色和银染观察蜗神经核的腹侧前核、腹侧后核、背侧核、章鱼样细胞核群的形态变化.结果 术后第2天及4个月时实验组小鼠ABR测试未检测出反应波形.脑干切片实验组蜗神经核内各核群的体积均较对照组明显减少,其中腹侧前核下降22%,腹侧后核下降40%,背侧核下降24%.神经元数量也减少,其中腹侧前核下降25%,腹侧后核下降47%,背侧核下降39%.腹侧后核的章鱼样细胞群变化最显著,细胞群体积下降达47%,神经元数量下降达60%,神经元面积下降19%.经Mann-Whimey U检验,P值均<0.05,差异具有统计学意义.结论经过4个月的听觉剥夺,成年小鼠蜗神经核出现以核群体积缩小、神经元数量减少为特征的退行性改变.

Neuronal degeneration of the auditory nervous center in the mouse model of cochlear ablation

Objective To study the long-term effect of cochlear ablation on cochlear nucleus (CN). Methods A total of 40 BABL/c adult mice were used in the present study. Mice were divided into experimental group and central group at random- In experimental group, the cochlea was destroyed with stainless steel needle under the anatomy microscopy. Mice were tested for ABR thresholds at second day and 4 months after operation to assess hearing sensitivity. Animals were allowed to survive for four months. Histological sections of the cochlear nucleus were evaluated with serial sections stained with Nissl staining and sliver staining alternatively. Morphological change in anteroventral cochlear nucleus (AVCN), posteroventral cochlear nucleus (PVCN), dorsal cochlear nucleus (DCN) and octopus cell area (OCA) was observed evaluated four month later after the cochlear ablation. Results In the experimental group, after operation, early components of ABR couldn't be recognized. The volume of CN was decreased dramatically and the cells were less comparing to the control group. The volume of AVCN after cochlear ablation showed a decline to 22% less than the control group, and the number of neurons also dropped by 25%. In PVCN, the decreased volume by 40% with significant neuronal loss of 47% was observed four month later after the cochlear ablation. And in DCN, the volume shrinking to 24% and the loss of neurons reached to 39%. The most significant change was observed in OCA (octopus ceU area), with the neuron numbers, the area and the volume of OCA decreased by 60%, 19%, and 47% respectively. There was a statistically significant difference (P < 0. 05, Mann-Whitoey U test) in the morphological changes between the two groups. Conclusion Neuronal degeneration was observed in cochlear nucleus after four months cochlear ablation.