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目的探讨模拟失重条件下,飞船内稳态噪声对豚鼠耳蜗形态与功能的影响。方法32只豚鼠随机分为单纯失重组16只、失重+稳态噪声组16只。后肢悬吊法模拟失重,暴露于模拟飞船内在天飞行段的噪声环境,共5天。实验前、实验结束后即刻和实验结束后3天测试脑干诱发电位(ABR)阈值,取耳蜗标本行扫描电镜和透射电镜观察。结果实验组实验结束后即刻ABR阈值较实验前及实验结束后3天均增高(P<0.01);实验结束后3天ABR阈值较实验前高(P<0.05);实验结束后即刻及实验结束后3天失重+稳态噪声组ABR阈值均较单纯失重组高(P<0.01)。扫描电镜观察实验组实验结束后即刻耳蜗内、外毛细胞均受损。实验结束后3天,单纯失重组少数耳蜗各回内、外毛细胞的损伤程度比实验结束即刻加重;失重+稳态噪声组耳蜗各回内毛细胞损伤较实验结束即刻重,外毛细胞损伤较实验结束即刻轻。实验组各时间段内毛细胞的损伤均重于外毛细胞,自第一回至第四回毛细胞损伤逐渐加重。透射电镜观察实验组耳蜗毛细胞及神经节细胞均可见空泡样改变,线粒体分布减少,细胞核固缩,可见细胞凋亡和细胞坏死两种细胞死亡现象。结论失重及失重+稳态噪声均可造成豚鼠耳蜗形态和功能损伤,后者造成的损伤更重。失重对耳蜗毛细胞损伤以内毛细胞为重,损伤从底回至顶回逐渐加重。实验结束后3天较实验后即刻的听功能有所恢复但内毛细胞损伤加重。
Objective To investigate the effects of spacecraft internal noise on the morphology and function of guinea pig cochlea under simulated weightlessness. Methods Thirty-two guinea pigs were randomly divided into simple weight loss group (n = 16), weight loss + steady-state noise group (n = 16) The hindlimb suspension method simulates weightlessness and is exposed to a noise environment simulating the inner flight section of the spacecraft for 5 days. The brainstem response (ABR) thresholds were measured before the experiment, immediately after the experiment and 3 days after the experiment. The cochlear specimens were observed under scanning electron microscope and transmission electron microscope. Results The threshold of ABR immediately after the end of experiment in experimental group was higher than that before experiment and 3 days after the end of experiment (P <0.01). The ABR threshold of experimental group at 3 days after the end of experiment was higher than that before experiment (P <0.05) After 3 days of weight loss and steady-state noise ABR threshold group than the simple weight loss group (P <0.01). Scanning electron microscopy observation experimental group immediately after the end of the cochlear outer and outer hair cells were damaged. Three days after the end of the experiment, the damage of inner and outer hair cells in all the cochlear cells in the simple weightlessness group was aggravated as compared with the end of the experiment. The damage of inner hair cells in the inner cochlear of the weightlessness and steady-state noise group was heavier than the end of the experiment, End immediately light. The damage of hair cells in the experimental group was heavier than that of the outer hair cells in each time period, and the damage of the first hair cell back to the fourth was gradually aggravated. Transmission electron microscopy showed that the cochlear hair cells and ganglion cells in the experimental group were all vacuolar-like changes, mitochondria distribution decreased, nuclear condensation, visible cell death and cell necrosis two kinds of cell death phenomenon. Conclusion Both weightlessness and weightlessness + steady-state noise can cause morphological and functional impairment of guinea pig cochlea, which results in more severe damage. Weight loss of hair cells within the cochlear hair cells within the injury, injury from the end back to the top gradually increased. Three days after the experiment, the auditory function recovered immediately after the experiment, but the injury of inner hair cells increased.