豚鼠线粒体DNA4568缺失与老年性聋的关系

目的 探讨豚鼠听觉器官中线粒体DNA(mitochondrial DNA, mtDNA)4568缺失与老年性聋的关系.方法 将44只豚鼠分为两组A组青年豚鼠22只;B组老年豚鼠22只.再将B组分为B1组(老年听力正常组6只)和B2组(老年聋组16只).应用听觉脑干反应(auditory brainstem response, ABR)测试豚鼠听力阈值,以左耳听阈为评判标准,并提取耳蜗螺旋器、听神经、大脑颞叶组织和外周血中的DNA,采用PCR技术检测mtDNA4568大片段缺失的情况,并与耳聋程度作比较. 结果 老年聋组(B2)豚鼠的ABR平均听阈值为(57.33±4.65)dBSPL,明显高于老年听力正常组B1[(23.00±1.43)dBSPL]和青年组[A组(15.90±1.05)dBSPL];老年组不同器官组织中mtDNA4568缺失率均明显高于青年组;老年聋组耳蜗螺旋器组织和听神经组织中mtDNA4568缺失率明显高于老年听力正常组;而大脑颞叶组织mtDNA4568缺失率在两组间差异无统计学意义;血液中仅极少数存在mtDNA缺失,未纳入统计分析.结论 豚鼠mtDNA4568缺失的发生与老龄有关;与听觉有关的耳蜗螺旋器组织和听神经组织中mtDNA4568缺失与老年性聋有关;大脑颞叶组织和外周血中mtDNA4568缺失与老年性聋的关系尚待进一步研究.

Mitochondrial DNA4568 deletions in guinea-pig associated with presbycusis

Objective To determine weather or not the mtDNA~(4568)deletions in guinea-pig contribute to the development of presbycusis.Methods Forty-four guinea-pigs were divided into 2 groups:group A(young control group,normal hearing,22 guineas)and group B(aged group).The group B was subdivided into group B_1(old normal hearing,6 guineas)and group B_2(old hearing loss,16 guineas).First the guineas were tested by auditory brainstem response(ABR),and then the Cortis's tissues,auditory nerve tissues,brain and blood were harvested and the total DNA was extracted.The mtDNA~(4568)deletion was analyzed by PCR.Results Hearing loss was occurred with age.The mtDNA~(4568)deletion incidence of aged group in all tissues was significant higher than that of young control group(P<0.05).The incidence of mtDNA deletion in Cortis's and auditory nerve with presbycusis(B_2 group)were significant higher than that of aged normal hearing group(B_1 group)(P<0.05).The incidence of mtDNA deletion in brain and blood was not significantly different between presbycusis and aged normal hearing group(P>0.05).Conclusion mtDNA~(4568)deletion of guinea-pig possibly contributes to aging and mtDNA~(4568)deletion in Cortis's and auditory nerve tissues of guinea-pig may be associated with presbycusis.There is no enough evidence to prove that the mtDNA~(4568)deletions in brain and blood are related with presbycusis.