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目的 :分析大鼠内耳组织线粒体DNA(mtDNA)片段缺失与氨基苷类抗生素 (AmAn)致聋的对应关系 ,探讨线粒体DNA片段缺失在老年大鼠AmAn耳毒易感中的可能作用。方法 :将Wistar大鼠 30只按月龄分为A组 (老龄鼠 ,>2 4个月龄 )和B组 (4个月龄鼠 ) ,每组 15只 ;均连续腹腔注射卡那霉素 (KM ) ,每日 5 0 0mg/kg ,共 10d。用药前、后测试听性脑干反应 (ABR)阈值 ,并用聚合酶链反应 (PCR)对大鼠内耳组织mtDNA483 4 缺失片段进行检测。结果 :①A ,B组大鼠用KM前、后 ,ABR反应阈提高 ,阈移均值分别为 :(42 .0 8± 8.5 9)dBpeSPL ,(12 .71± 4 .4 2 )dBpeSPL ,二者间差异有统计学意义 (P <0 .0 1) ;②A组大鼠有 10只存在mtDNA483 4 缺失 ,其中检测到mtDNA483 4 缺失的 10只大鼠和未检测到此缺失的 5只大鼠 ,阈移均值分别为 (45 .0 0± 7.6 7)dBpeSPL ,(33.33± 4 .0 8)dBpeSPL ,两者间差异亦有统计学意义 (P <0 .0 1) ;而B组大鼠未发现此片段缺失。结论 :老龄大鼠内耳组织存在mtDNA片段缺失 ,且此片段缺失可能增加其对AmAn耳毒作用的敏感性
OBJECTIVE: To analyze the relationship between mitochondrial DNA (mtDNA) fragment deletion and amylase-induced deafness in rat inner ear tissue and to explore the possible role of deletion of mitochondrial DNA fragment in susceptibility to AmAn ototoxicity in aged rats. Methods: Thirty Wistar rats were divided into A group (aged rats,> 24 months old) and B group (4 months old rats) by the age of 15, each group was given continuous intraperitoneal injection of kanamycin (KM), daily 500 mg / kg, a total of 10d. The threshold of auditory brainstem response (ABR) was measured before and after treatment, and the mtDNA483 4 deletion fragment in rat inner ear tissue was detected by polymerase chain reaction (PCR). Results: ① The ABR thresholds of both groups before and after KM were increased in group A and B, and the mean threshold shifts were (42.0 ± 8.8) dBpeSPL and (12.71 ± 4.42) dBpeSPL, respectively (P <0.01). ② There were 10 mtDNA483 4 deletion in group A, in which 10 mtDNA483 4 deletion and 5 mtDNA deletion were detected, The mean threshold shift values were (45.0 ± 7.67) dBpeSPL and (33.33 ± 4.80) dBpeSPL, respectively, with significant differences between the two groups (P <0.01) This fragment is missing. CONCLUSION: The absence of mtDNA fragment in the inner ear of aged rats and the loss of this fragment may increase its sensitivity to AmAn ototoxicity