Role of MiR-34a/Bcl-2 apoptotic pathway in age-related hearing loss of mouse model / 中华老年医学杂志

ABSTRACT

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.