老年性聋小鼠耳蜗带状突触损伤特点及机制研究
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摘要
目的研究老年性聋耳蜗带状突触数量在耳蜗各回的变化特点及其可能机制的研究。方法根据年龄将C57BL/6J小鼠分为1月龄组和12月龄组(每组12只),听性脑干反应(Auditory Brain Response, ABR)检测两组小鼠听功能,免疫组织化学染色检测两组小鼠耳蜗带状突触数量,Western blot检测两组小鼠耳蜗Ucp2蛋白的表达。结果和1月龄小鼠相比较,12月龄小鼠ABR阈值在8kHz显著升高(t=12.226, P<0.01),在16kHz和32kHz阈值均超过90dB SPL;12月龄小鼠在90dB SPL声强下ABR I波幅值在8kHz显著降低(t=5.102, P<0.01);12月龄小鼠耳蜗带状突触数量在耳蜗顶回(t=10.230, P<0.01)、中回(t=3.386, P<0.05)和底回(t=17.076, P<0.01)均显著减少,其中耳蜗底回数量减少最明显;12月龄小鼠耳蜗Ucp2蛋白水平显著增加(t=11.429, P<0.01)。结论在小鼠老化的过程中,耳蜗底回的带状突触最容易损伤丢失,其次是耳蜗顶回和中回,线粒体Ucp2可能在耳蜗带状突触损伤过程中起到重要作用。
Objective To report changes of cochlear ribbon synapses in all turns associated with age-related hearing loss(ARHL) and possible underlying mechanisms. Methods One-and 12-months old C57 BL/6 J mice received auditory brain response(ABR) tests and their ribbon synapses were marked by Ctbp2 using immunohistochemical analysis.Protein expression of uncoupling protein 2(Ucp2) was assessed by Western Blot. Results Compared with the 1-month old mice, ABR thresholds at 8 k Hz were significantly increased in 12-months old mice(t=12.226, P<0.01), and over 90 dB SPL at 16 and 32 kHz. Amplitudes of wave I at 90 dB SPL for 8 kHz in these mice were also lower than in 1-month old mice(t=5.102, P<0.01). Compared with 1-month old mice, the number of ribbon synapses in all turns were decreased in 12-months old mice, especially in the basal turn(t=17.076, P< 0.01), followed by the apical(t=10.230, P<0.01) and middle(t=3.386, P<0.05) turns. Protein expression of Ucp2 in the cochlea of 12-months old mice was higher than in 1-month old mice(P<0.01). Conclusion In ARHL, ribbon synapses in the basal turn appear to be most vulnerable to damage, followed by those in the apical and middle turns. Mitochondrial Ucp2 may play an important role in the damage of cochlear ribbon synapses in ARHL.
Objective To report changes of cochlear ribbon synapses in all turns associated with age-related hearing loss(ARHL) and possible underlying mechanisms. Methods One-and 12-months old C57 BL/6 J mice received auditory brain response(ABR) tests and their ribbon synapses were marked by Ctbp2 using immunohistochemical analysis.Protein expression of uncoupling protein 2(Ucp2) was assessed by Western Blot. Results Compared with the 1-month old mice, ABR thresholds at 8 k Hz were significantly increased in 12-months old mice(t=12.226, P<0.01), and over 90 dB SPL at 16 and 32 kHz. Amplitudes of wave I at 90 dB SPL for 8 kHz in these mice were also lower than in 1-month old mice(t=5.102, P<0.01). Compared with 1-month old mice, the number of ribbon synapses in all turns were decreased in 12-months old mice, especially in the basal turn(t=17.076, P< 0.01), followed by the apical(t=10.230, P<0.01) and middle(t=3.386, P<0.05) turns. Protein expression of Ucp2 in the cochlea of 12-months old mice was higher than in 1-month old mice(P<0.01). Conclusion In ARHL, ribbon synapses in the basal turn appear to be most vulnerable to damage, followed by those in the apical and middle turns. Mitochondrial Ucp2 may play an important role in the damage of cochlear ribbon synapses in ARHL.
引文
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14 Cai R,Montgomery SC,Graves KA,et al.The FBN rat model of aging:investigation of ABR waveforms and ribbon synapse changes[J].Neurobiol Aging,2018,6253-63.
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18 Stowers RS,Megeath LJ,Gorska-Andrzejak J,et al.Axonal transport of mitochondria to synapses depends on Milton,a novel Drosophila protein[J].Neuron,2002,36(6):1063-1077.
19 Li Z,Okamoto K,Hayashi Y,et al.The importance of dendritic mitochondria in the morphogenesis and plasticity of spines and synapses[J].Cell,2004,119(6):873-887.
20王驰,柳柯,赵立东,等.老年性聋耳蜗带状突触数量在时空上的改变[J].中华耳科学杂志,2016,14(1):32-36.Wang C,Liu K,Zhao LD,et al.Time and frequency dependent changes of cochlear ribbon synapses in age related hearing loss.Chinese Journal of otology,2016,14(1):32-36.
21 Someya S,Prolla TA.Mitochondrial oxidative damage and apoptosis in age-related hearing loss[J].Mechanisms of Ageing and Development,2010,131(7-8):480-486.
22 Huang Q,Tang JG.Age-related hearing loss or presbycusis[J].European Archives of Oto-Rhino-Laryngology,2010,267(8):1179-1191.
23 Krauss S,Zhang CY,Lowell BB.The mitochondrial uncoupling-protein homologues[J].Nat Rev Mol Cell Bio,2005,6(3):248-261.
24 Mailloux RJ,Harper ME.Uncoupling proteins and the control of mitochondrial reactive oxygen species production[J].Free Radical Bio Med,2011,51(6):1106-1115.
2 Gates GA,Mills JH.Presbycusis[J].Lancet,2005,366(9491):1111-1120.
3 Goman AM,Lin FR.Prevalence of hearing loss by severity in the united States[J].Am J Public Health,2016,106(10):1820-1822.
4 Sergeyenko Y,Lall K,Liberman MC,et al.Age-related cochlear synaptopathy:An Early-Onset Contributor to Auditory Functional Decline[J].Journal of Neuroscience,2013,33(34):13686-13694.
5 Wang Y,Manis PB.Synaptic transmission at the cochlear nucleus endbulb synapse during age-related hearing loss in mice[J].JNeurophysiol,2005,94(3):1814-1824.
6 Matthews G,Fuchs P.The diverse roles of ribbon synapses in sensory neurotransmission[J].Nature Reviews Neuroscience,2010,11(12):812-822.
7 Du Z,Yang Q,Liu L,et al.Nadph oxidase 2-dependent oxidative stress,Mitochondrial Damage and Apoptosis in the Ventral Cochlear Nucleus of D-Galactose-Induced Aging Rats[J].Neuroscience,2015,286281-292.
8 Pecqueur C,Alves-Guerra MC,Gelly C,et al.Uncoupling protein 2,in vivo distribution,induction upon oxidative stress,and evidence for translational regulation[J].Journal of Biological Chemistry,2001,276(12):8705-8712.
9 Bo JS,Xie SY,Guo Y,et al.Methylglyoxal impairs insulin secretion of pancreatic beta-Cells through increased production of ROS and mitochondrial dysfunction mediated by upregulation of Ucp2 and MAPKs[J].J Diabetes Res,2016(2016):2029854.
10 Mikaelian DO.Development and degeneration of hearing in the C57/b16 mouse:relation of electrophysiologic responses from the round window and cochlear nucleus to cochlear anatomy and behavioral responses[J].Laryngoscope,1979,89(1):1-15.
11 Li HS,Borg E.Age-related loss of auditory sensitivity in two mouse genotypes[J].Acta Otolaryngol,1991,111(5):827-834.
12 Henry KR,Chole RA.Genotypic differences in behavioral,physiological and anatomical expressions of age-related hearing loss in the laboratory mouse[J].Audiology,1980,19(5):369-383.
13李晓瑞,蒋兴旺,张延平.C57BL/6J小鼠随年龄增长耳蜗内毛细胞带状突触数量变化的观察[J].中华耳科学杂志,2015,23(2):176-180.Li XR,Jiang XF,ZhangYP.The changes of the number of ribbon synapse in inner hair cells of C57BL/6J mice with age[J].Chinese Journal of Otology,2015,23(2):176-180.
14 Cai R,Montgomery SC,Graves KA,et al.The FBN rat model of aging:investigation of ABR waveforms and ribbon synapse changes[J].Neurobiol Aging,2018,6253-63.
15 Paquette ST,Gilels F,White PM.Noise exposure modulates cochlear inner hair cell ribbon volumes,correlating with changes in auditory measures in the FVB/nJ mouse[J].Sci Rep-Uk,2016,6.
16 Liu K,Chen DS,Guo WW,et al.Spontaneous and Partial Repair of Ribbon Synapse in Cochlear Inner Hair Cells After Ototoxic Withdrawal[J].Mol Neurobiol,2015,52(3):1680-1689.
17 Verstreken P,Ly CV,Venken KJT,et al.Synaptic mitochondria are critical for mobilization of reserve pool vesicles at Drosophila neuromuscular junctions[J].Neuron,2005,47(3):365-378.
18 Stowers RS,Megeath LJ,Gorska-Andrzejak J,et al.Axonal transport of mitochondria to synapses depends on Milton,a novel Drosophila protein[J].Neuron,2002,36(6):1063-1077.
19 Li Z,Okamoto K,Hayashi Y,et al.The importance of dendritic mitochondria in the morphogenesis and plasticity of spines and synapses[J].Cell,2004,119(6):873-887.
20王驰,柳柯,赵立东,等.老年性聋耳蜗带状突触数量在时空上的改变[J].中华耳科学杂志,2016,14(1):32-36.Wang C,Liu K,Zhao LD,et al.Time and frequency dependent changes of cochlear ribbon synapses in age related hearing loss.Chinese Journal of otology,2016,14(1):32-36.
21 Someya S,Prolla TA.Mitochondrial oxidative damage and apoptosis in age-related hearing loss[J].Mechanisms of Ageing and Development,2010,131(7-8):480-486.
22 Huang Q,Tang JG.Age-related hearing loss or presbycusis[J].European Archives of Oto-Rhino-Laryngology,2010,267(8):1179-1191.
23 Krauss S,Zhang CY,Lowell BB.The mitochondrial uncoupling-protein homologues[J].Nat Rev Mol Cell Bio,2005,6(3):248-261.
24 Mailloux RJ,Harper ME.Uncoupling proteins and the control of mitochondrial reactive oxygen species production[J].Free Radical Bio Med,2011,51(6):1106-1115.