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目的 :探讨线粒体DNA缺失的组织器官间差异及其与老化和老年性耳聋的关系。方法 :依月龄将大鼠分为青年、中年和老年组 ;测试ABR阈值后从其不同器官组织和外周血中提取DNA ;PCR检测线粒体DNA4 83 4缺失 ,定量分析 ;克隆、测序。结果 :①随年龄增加 ,大鼠的ABR平均阈值明显升高 ;②所有老年大鼠的耳蜗、蜗核、大脑、心肌 (1例除外 )、肝脏和肌肉组织中均存在mtDNA4 83 4缺失 ,外周血仅少数缺失 ;③中青年组线粒体DNA4 83 4缺失的发生率和缺失占总mtDNA的百分比均低于老年组 (P <0 0 1) ;④mtDNA4 83 4缺失存在明显的器官组织间差异 ,肝脏组织中缺失占总mtDNA的百分比最高。结论 :大鼠多种器官组织中mtDNA4 83 4缺失随增龄而增加 ,而且存在器官组织间差异 ,检测外周血白细胞的mtDNA缺失并不能反映体内各器官组织中mtDNA缺失的发生情况 ,与听觉有关的耳蜗、蜗核组织中mtDNA缺失与老年聋的发生有关。
Objective: To investigate the difference of mitochondrial DNA-deleted tissues and organs and its relationship with senile deafness and senile deafness. Methods: Rats were divided into young, middle-aged and old groups according to age. DNA was extracted from different organs and peripheral blood after ABR threshold test. Mitochondrial DNA4 83 4 deletion was detected by PCR and cloned and sequenced. Results ① The average threshold of ABR in rats increased significantly with age; ② The mtDNA4 83 4 deletion in cochlear, cochlear nucleus, brain, myocardium (except 1), liver and muscle tissues of all the aged rats, (3) The incidence of mtDNA 4 83 4 deletion and the percentage of total mtDNA deletion in young group were lower than those in the elderly group (p 0 01). There was a significant difference in organ tissue between the deletion of mtDNA4 83 4 and liver Tissues lost the highest percentage of total mtDNA. CONCLUSION: The mtDNA4 83 4 deletion in multiple organs and tissues of rats increases with aging, and there are differences between organs and tissues. Detection of mtDNA deletions in peripheral blood leukocytes does not reflect the occurrence of mtDNA deletion in various organs and tissues and is related to hearing Of the cochlea, cochi nuclear mitochondrial DNA deletion and senile deaf occurred.