快速老化小鼠听功能及耳蜗组织中p-ERK1/2的增龄性变化

Degenerative Changes of Auditory Functions and Age-related Expression of p-ERK1/2 in the Cochlea of the Senescence Accelerated Mouse

目的探讨快速老化小鼠的听功能及耳蜗组织中磷酸化的细胞外信号调节激酶1/2(phosphorylated extracellular signal-regulated protein kinases,p-ERK1/2)表达的增龄性变化。方法选用3、5、7月龄的快速老化小鼠亚系8(SAMP8)各6只,分别进行8kHz短纯音听性脑干反应(ABR)检测,并用免疫组化染色方法分别检测各月龄组小鼠耳蜗组织p-ERK1/2的表达,分析其増龄性变化。结果 3、5、7月龄SAMP8小鼠ABR阈值左耳分别为31.817±1.228、54.329±1.459、58.330±1.252dB SPL,右耳分别为32.474±1.041、53.485±1.385、57.842±1.173dB SPL,SAMP8小鼠双耳听性脑干反应阈值随月龄增加而明显提高(P<0.05);3月龄小鼠螺旋神经节细胞、毛细胞中p-EPK1/2平均光密度值分别为0.699 7±0.018 8、0.651 9±0.025 2;5月龄小鼠螺旋神经节细胞、毛细胞中p-EPK1/2平均光密度值分别为0.621 5±0.014 7、0.591 2±0.010 2;7月龄小鼠螺旋神经节细胞、毛细胞中p-EPK1/2平均光密度值分别为0.575 3±0.015 5、0.559 3±0.006 7,p-EPK1/2在不同月龄快速老化小鼠耳蜗组织中的表达光密度值随着月龄增加而显著降低(P<0.05)。结论快速老化小鼠耳蜗组织中p-EPK1/2蛋白的表达水平随着年龄相关性听功能减退而降低,推测p-EPK1/2可能与维持耳蜗功能状态及听觉形成有关。

Objective To investigate degenerative changes of auditory functions and age -related expression of phosphorylated extracellular signal -regulated protein kinases1/2（p-ERK1/2） in the cochlea of the senescence accelerated mouse .Methods The 3 ,5 ,7 months old mice were selected for the study and each group had 6 mice . The 8 kHz tone burst auditory thresholds and age -related expression of p -ERK1/2 in the cochlea were studied in the senescence accelerated mouse/prone 8（SAMP8） at 3 ,5 ,7 months .The expression of p -ERK1/2 was analyzed by the optical density of immunohistochemical staining .Results For the auditory function evaluation ：The SAMP 8 developed a progressive hearing loss at 8 kHz which showed an age -related significant increase （P〈 0 .05） .The ABR thresholds in 3 ,5 ,7 months old groups in the left ear were 31 .817 ± 1 .228 ,54 .329 ± 1 .459 ,58 .330 ± 1 .252 dB SPL ,respectively .In the right ears ,the ABR threshold were 32 .474 ± 1 .041 ,53 .485 ± 1 .385 ,57 .842 ± 1 .173 dB SPL ,respectively .p-ERK1/2 protein expressed in the cochlea of the SAMP8 throughout the development sta‐ges ,which developed an age-related significant decrease （P〈0 .05） .The average optical density of p -ERK1/2 in the spiral ganglion cells in the 3 ,5 ,7 months old mice were 0 .699 7 ± 0 .018 8 ,0 .621 5 ± 0 .014 7 ,0 .575 3 ± 0 .015 5 ,respectively .In the hair cells ,they w ere 0 .651 9 ± 0 .025 2 ,0 .591 2 ± 0 .010 2 ,0 .559 3 ± 0 .006 7 respec‐tively .Conclusion The expression level of p -ERK1/2 protein decreases when the SAMP 8 develops a progressive hearing loss .This indicates that p-ERK1/2 protein probably has relationship with maintaining functional status of the cochlea and the auditory formation .