风洞噪声对小鼠听性脑干反应和耳蜗超微结构的影响及雌激素的防护作用

发布时间：2019-06-09 13:00

【摘要】：目的根据现场采集相关数据模拟风洞噪声，建立小鼠噪声性耳聋模型，观察风洞噪声对小鼠听性脑干反应和耳蜗超微结构的损伤。脱离风洞噪声后给予雌激素干预，观察雌激素对小鼠ABR阈值及耳蜗超微结构的作用，探讨雌激素对噪声性听力损伤的影响，为噪声性耳聋的预防和治疗提供依据。方法40只昆明种小鼠（雄性）随机分为单纯噪声组（A组）、雌激素治疗组（B组），每组20只，分别暴露于模拟风洞噪声环境中，每天8小时，连续7天。B组噪声暴露结束后30min肌肉注射苯甲酸雌二醇0.15mg/只，而A组则不给予注射苯甲酸雌二醇。分别于实验前、噪声暴露3天、噪声暴露7天、脱离噪声后恢复3天、脱离噪声后恢复7天共5个时间节点测试各组小鼠听性脑干反应(ABR)阈值，并于噪声暴露7天和脱离噪声后恢复7天时将小鼠快速断头、迅速取出耳蜗，2.5％戊二醛固定液进行离体耳蜗灌注，并在固定液中固定4小时。(1)采用硬剥法暴露出基底膜，然后进行脱水、干燥、镀金等处理，扫描电镜观察并拍照。(2)将标本浸入10％乙二胺四乙酸中脱钙3周，然后进行脱水、包埋、固化、切片及染色处理，透射电镜下观察并拍照。结果两组小鼠实验前ABR阈值无统计学差异，接触噪声后两组小鼠均有明显听力损失，表现为阈值随噪声暴露时间延长而升高，噪声暴露3天、噪声暴露7天的ABR阈值均比实验前增高，但两组组间无统计学差异。当脱离噪声后，两组听力均有不同程度恢复，脱离噪声后恢复3天、脱离噪声后恢复7天时雌激素治疗组ABR阈值较单纯噪声组低，两组间有统计学差异。扫描电镜显示：在噪声暴露7天后两组小鼠耳蜗损伤严重，内、外毛细胞限局性片状广泛缺失，Corti器塌陷、变形。脱离噪声恢复7天时，单纯噪声组小鼠耳蜗内、外毛细胞限局性点状缺失，Corti器塌陷、皱缩、变形；而雌激素治疗组小鼠耳蜗病变较轻，只有内毛细胞轻度散乱、融合，外毛细胞基本正常。透射电镜显示：在噪声暴露7天后两组小鼠耳蜗内、外毛细胞胞浆内均有较多空泡形成，细胞线粒体减少。脱离噪声恢复7天时，单纯噪声组小鼠耳蜗外毛细胞线粒体大致正常，，基本无空泡，内毛细胞虽有空泡形成，但较噪声暴露7天时数量减少；雌激素治疗组小鼠耳蜗内毛细胞胞浆内仅有很少量空泡形成，外毛细胞线粒体均正常，无空泡形成。结论风洞噪声能明显损伤小鼠听性脑干反应，其ABR阈值随噪声暴露时间延长而升高，脱离噪声后两组均有不同程度恢复，雌激素治疗组恢复效果好于单纯噪声组。风洞噪声同时造成小鼠耳蜗超微结构的损伤，雌激素治疗组损伤较单纯噪声组明显减轻，与听力检查结果相吻合。雌激素对小鼠风洞噪声性耳聋具有保护作用。
[Abstract]:Objective to establish a model of noise-induced deafness in mice according to the relevant data collected in the field, and to observe the damage of auditory brainstem response and cochlear ultrastructure induced by wind tunnel noise in mice. The effects of estrogen on ABR threshold and cochlear ultrastructure in mice were observed after breaking away from wind tunnel noise, and the effect of estrogen on noise-induced hearing loss was discussed, which provided the basis for the prevention and treatment of noise-induced deafness. Methods 40 Kunming mice (male) were randomly divided into simple noise group (group A) and estrogen treatment group (group B), with 20 mice in each group, exposed to simulated wind tunnel noise environment for 8 hours a day. For 7 days, group B received intramuscular injection of Estradiol benzoate 0.15mg/ into 30min after noise exposure, while Group A was not injected with Estradiol benzoate. Before the experiment, noise exposure for 3 days, noise exposure for 7 days, recovery from noise for 3 days, and recovery for 7 days after noise, five time nodes were used to test the (ABR) threshold of auditory brainstem response in each group. When the mice were exposed to noise for 7 days and recovered from noise for 7 days, the mice were quickly decapitated, the cochlea were quickly removed, and 2.5% glutaraldehyde fixation solution was perfused into the isolated cochlea. And fixed in the stationary solution for 4 hours. (1) the basement membrane was exposed by hard stripping method, then dehydrated, dried and gilded, observed and photographed by scanning electron microscope. (2) the specimens were immersed in 10% ethylenediamine tetraacetic acid for 3 weeks. Then dehydration, embedding, curing, slicing and staining were carried out, and observed and photographed under transmission electron microscope. Results there was no significant difference in ABR threshold between the two groups before the experiment. After exposure to noise, the mice in the two groups had obvious hearing loss, which showed that the threshold increased with the prolongation of noise exposure time and exposed to noise for 3 days. The ABR threshold of noise exposure for 7 days was higher than that before the experiment, but there was no significant difference between the two groups. When the noise was removed, the hearing of the two groups recovered to varying degrees, and the ABR threshold of the estrogen treatment group was lower than that of the simple noise group 3 days after the noise removal and 7 days after the noise removal, and there was significant difference between the two groups. Scanning electron microscope (SEM) showed that after 7 days of noise exposure, the cochlea of the two groups was seriously damaged, the localized flakes of inner and outer hair cells were widely deleted, and the Corti apparatus collapsed and deformed. After 7 days of recovery from noise, focal punctate deletion of outer hair cells, collapse, shrinkage and deformation of Corti apparatus were found in the cochlea of mice in the simple noise group. In the estrogen treatment group, the cochlear lesions were mild, only the inner hair cells were slightly scattered, fusion and the outer hair cells were basically normal. Transmission electron microscope showed that more vacuoles were formed in the cytoplasm of outer hair cells and the number of mitochondria decreased in the cochlea of the two groups after 7 days of noise exposure. When the isolated noise recovered for 7 days, the mitochondria of the outer hair cells of the cochlea in the noise group were about normal, and there were no vacuoles. Although the vacuoles were formed in the inner hair cells, the number of the inner hair cells was lower than that in the noise exposure group at 7 days. In estrogen treatment group, only a small number of vacuoles were formed in the cytoplasm of hair cells in cochlea of mice treated with estrogen, and the mitochondria of outer hair cells were normal and no vacuoles were formed. Conclusion Wind tunnel noise can significantly damage auditory brainstem response in mice, and the ABR threshold increases with the prolongation of noise exposure time. Both groups recovered to varying degrees after noise removal. The recovery effect of estrogen treatment group was better than that of simple noise group. Wind tunnel noise also caused the damage of cochlea ultrastructure in mice. The damage in estrogen treatment group was significantly less than that in simple noise group, which was consistent with the results of hearing examination. Estrogen has protective effect on wind tunnel noise induced deafness in mice.
【学位授予单位】：安徽医科大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R764

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