去乙酰化酶 SIRT1在 C57BL／6小鼠耳蜗的年龄相关性表达

摘要

Objective To investigate the NAD+ - dependent protein deacetylase SIRT1 expression in the cochlea of C57BL/6 mice ,a mouse model of age - related hearing loss(AHL) .Methods A total of 46 C57BL/6 mice were used ,and were divided into 2 groups ;according the age ,there were young group (1 ~ 2 months old ,23 mice) and old group (12 ~ 16 months old ,23 mice) .ABR measurements were performed on young and old C57BL/6 mice . The expression of SIRT1 in the cochlea was detected by qRT - PCR and immunofluorescence .Results The ABR thresholds in the old mice(4 kHz :82 .7 ± 7 .32 dB SPL ,8 kHz :80 .9 ± 7 .8 dB SPL ,16 kHz :89 .3 ± 5 .5 dB SPL ,32 kHz :89 .9 ± 4 dB SPL) were significantly higher than those in the young C57BL/6 mice(4 kHz :52 .1 ± 8 .3 dB SPL ,8 kHz :40 .5 ± 6 .1 dB SPL ,16 kHz :50 .7 ± 9 .4 dB SPL ,32 kHz :57 .6 ± 11 .9 dB SPL)(P < 0 .001) .SIRT1 mRNA expression was significantly decreased in the cochlea of old C57BL/6 mice in comparison with young mice ( P <0 .01) .SIRT1 protein was abundantly expressed in the inner hair cells ,outer hair cells ,supporting cells ,strial marginal cells ,strial intermediated cells ,and spiral ganglion neurons .The positive area and the average flourescence intensity of SIRT1 protein were reduced in old C57BL/6 mice(P< 0 .001) .Conclusion The down - regulation of SIRT1 mRNA and protein expression in the older C57BL/6 mouse cochlea may be correlated with the pathogenesis of AHL .%目的：探讨依赖烟酰胺腺嘌呤二核苷酸（nicotin-amide adenine dinucleotide ，NAD＋）的去乙酰化酶沉默信息调节因子2（silent information regulator2，Sir2）相关酶1（sirtuin1，SIRT1）在不同月龄C57BL/6小鼠耳蜗的表达及其与年龄相关性听力损失（age-related hearing loss ，AHL）的关系。方法检测1～2月龄（青年组，23只）和12～16月龄（老年组，23只）C57BL/6小鼠的听性脑干反应（ABR ）阈值，并应用实时定量聚合酶链反应（real-time quantitative polymerase chain reaction ，qRT -PCR）和免疫荧光检测SIRT1在两组动物耳蜗中的表达。结果老年组小鼠4、8、16、32 kHz的ABR反应阈分别为82．7±7．32、80．9±7．8、89．3±5．5、89．9±4．0 dB SPL ，明显高于青年组（分别为52．1±8．3、40．5±6．1、50．7±9．4、57．6±11．9 dB SPL ）（P＜0．001）；青年组及老年组小鼠耳蜗均有SIRT1 mRNA表达，但其在老年组的表达明显低于青年组（P＜0．01）；SIRT1蛋白主要表达在内毛细胞、外毛细胞、支持细胞、血管纹细胞和螺旋神经节神经细胞，老年组耳蜗SIRT1蛋白免疫荧光的阳性面积和平均荧光强度均较青年组明显下降（P＜0．001）。结论 C57BL/6小鼠耳蜗中SIRT1 mRNA和蛋白表达随年龄增长而下调，提示SIRT1可能参与AHL的发生。