听觉器官线粒体DNA缺失在老年聋发病中的意义

目的 探讨听觉器官中线粒体DNA缺失在老年聋发病中的意义。方法:饲养不同年龄组的大鼠,测试ABR阈值,PCR检测其耳蜗、蜗核、大脑、颞肌和外周血中是否存在mtDNA~(4834)缺失,对存在的缺失进行定量分析;PCR产物进行克隆、测序。结果:老年组大鼠的ABR平均阈值为92.22±10.60dBSPL(n=20),中年组为42.75±5.73dBSPL(n=24),青年组为30.50±1.54dBSPL(n:24),老年组大鼠的ABR阈值明显高于中年组和青年组,其差别具有非常显著性的意义(方差分析,P<0.01);(2)所有老年大鼠的听觉器官和颞肌中均存在mtD-NA~(4834)缺失,其缺失发生率高于中年组,青年组mtDNA~(4834)缺失发生率最低;(3)定量分析显示不同年龄大鼠听觉器官中mtDNA~(4834)缺失占总mtDNA的百分比不同,老年组mtDNA~(4834)缺失占总mtDNA的百分比高于中年组。结论:老年大鼠的ABR阈值明显升高,其包括耳蜗、蜗核在内的多种组织中普遍存在的mtDNA~(4834)缺失,提示mtDNA缺失在老化和老年聋的发生中具有重要意义。

Mitochondrial DNA deletions associated with age- related hearing loss

Objective To determine weather or not the mtDNA deletions associated with aging and age - related hearing loss in wistar rats. Methods Wistar rats from 3 age groups were used. All animals were tested for auditory sensitivity using the auditory brainstem response (ABR). The cochlea, cochlear nucleus, brain, temporal muscle and blood were harvested and the total DNA was extracted. The presence of mtDNA4834 deletions, corresponding to mtDNA4977 deletions in human, in hearing organs was examined using polymerase chain reaction (PCR), and the mtDNA4834 deletions were quantitated. Results (1) The results showed a progressive reduction in auditory sensitivity with age. (2) The mtDNA studies identify a significant increase in the presence of the mtDNA4834 deletion in the hearing organs of the aged subjects compared with the young subjects (P <0. 01). (3) Quantitation showed the mtDNA4834 level is an age - related manner in all hearing organ tissues. The mtDNA4834 deletions were found to be at its highest level in aged subjects. Conclusions These findings raise the possibility that the mtDNA4834 deletions associated with presbyacusis, as well as with aging.