目的 探讨MiR-34a/Bcl-2凋亡通路在老年性聋发病机制中的可能作用. 方法 采用C57BL/6年龄相关性聋小鼠模型,4周龄小鼠和12月龄小鼠为研究对象,采用听性脑干诱发电位检查(ABR)进行听力测试,并检测听皮层神经元凋亡情况,采用聚合酶链反应(PCR)及免疫印迹分析(Western Blot)检测miR-34a/Bcl-2通路在年龄相关性聋小鼠听皮层的表达情况,并检测经典凋亡通路Caspase3的活化情况. 结果 ABR结果显示12月龄小鼠在频率为4 kHz、8 kHz、16 kHz、32kHz的阈值分别为(80.0±2.5)dBHL、(74.0±3.5) dBHL、(86.0±4.6)dBHL、(87.0±6.6)dBHL,高于4周龄小鼠的(32.0±4.5)dBHL、(51.0±1.2)dBHL、(51.0±3.5)dBHL、(56.0±1.5)dBHL(均P＜0.05).12月龄小鼠听皮层神经元数量减少,凋亡神经元增多,miR-34a的表达升高(t=6.02,P=0.001),Bcl-2的表达下降(t=7.12,P=0.032),Bax的表达升高(t=6.51,P=0.012),Caspase-3表达升高,4周龄小鼠与12月龄小鼠比较,差异有统计学意义(P=0.023). 结论 MiR34a/Bcl-2介导的凋亡通路可能是年龄相关性聋发病的机制之一.%Objective To explore the possible mechanism of miR 34a/Bcl-2 apoptotic pathway in the mouse model of age-related hearing loss.Methods A C57BL/6 mouse model of age-related hearing loss was conducted,and 4-week-old and 12-month-old mice were considered as the objects.The auditory brainstem response (ABR) was used to test the hearing function.The TdT-mediated dUTP nick end labeling (TUNEL) was used to observe the apoptosis of neuron in auditory cortex.The mRNA and protein levels of miR-34a,Bcl-2 and caspase 3 were detected by real-time PCR and Western bloting,respectively.Results The ABR showed that the hearing threshold level at 4,8,16,32 kHz were higher in 12-month-old mice than in 4-week-old mice [(80.0±2.5) dBHL vs.(32.0 ±4.5) dBHL,(74.0±3.5) dBHL vs.(51.0±1.2) dBHL,(86.0±4.6) dBHL vs.(51.0±3.5) dBHL,(87.0±6.6) dBHL vs.(56.0±1.5) dBHL,all P＜0.05].Compared with 4 week-old mice,the total number of neurons in auditory cortex was decreased,the number of apoptosis neurons was increased,the expressions of miR-34a (t=6.02,P=0.001),Bax (t=6.51,P=0.012) and Caspase 3 (P=0.023) rised,and the expression of Bcl-2 (t=7.12,P=0.032) declined in 12 month-old mice.Conclusions The activation of miR-34a/Bcl-2 apoptotic pathway may be one of the mechanisms of age-related hearing loss.
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