c-Maf基因在小鼠耳蜗内外毛细胞中的表达及意义

目的研究c-Maf基因在小鼠耳蜗内、外毛细胞中的表达、分布特点及意义。方法 1)根据形态上的差异分离收集成年小鼠内、外毛细胞,利用Microarray基因芯片技术分别检测内、外毛细胞c-Maf基因RNA水平的表达;2)全耳蜗基底膜铺片,免疫组织化学染色后激光共聚焦显微镜观察c-Maf蛋白在不同发育阶段小鼠耳蜗内、外毛细胞中的分布特点及表达,并使用软件Image Pro Plus进行c-Maf蛋白定量分析。结果 1)耳蜗内、外毛细胞c-Maf基因RNA水平相近;2)c-Maf蛋白主要表达于成年小鼠的耳蜗内外毛细胞胞质,在内毛细胞的核下区表达强于核上区,且在内、外毛细胞的表达强度相近;3)c-Maf蛋白在小鼠出生后0天、7天、12天及成年小鼠耳蜗内、外毛细胞稳定表达。结论 c-Maf蛋白从出生开始在小鼠耳蜗内、外毛细胞上稳定表达,且在成年小鼠内毛细胞的核下区表达较强,表明其可能在毛细胞生长发育以及功能维持中发挥重要的作用。     

小鼠耳蜗内外毛细胞胞吞功能的实验研究

目的研究小鼠内外毛细胞胞吞功能的异同,探讨毛细胞胞吞功能与动物听功能之间的关系。方法选择出生后1月龄的正常C57BL/6J小鼠耳蜗基底膜在体外培养,以染料FM1-43为胞吞示踪剂,应用活细胞成像技术观察耳蜗内外毛细胞胞吞现象。结果内毛细胞的胞吞活动主要集中在细胞底部及核下区,而外毛细胞的胞吞活动则主要集中在核上区和外侧壁区。而且,在不同的观察时间点上,内毛细胞对FM1-43的摄入量均显著高于外毛细胞(P<0.05)。结论内毛细胞的胞吞活动集中出现在细胞底部及核下区,说明这种胞吞活动与内毛细胞带状突触的功能密切相关;外毛细胞的胞吞活动主要出现在核上区及细胞外侧壁,表明这种活动更多参与了外毛细胞纤毛及离子通道。内毛细胞比外毛细胞具有更强大的胞吞功能,表明内毛细胞在听功能的发育和维持中发挥着更为关键的作用。     

谷氨酸-天冬氨酸转运体在豚鼠耳蜗的分布

目的研究谷氨酸-天冬氨酸转运体(glutamate—aspartate transporters，GLAST)在正常豚鼠耳蜗内的分布，为探讨GLAST在防止耳蜗谷氨酸(Glu)神经毒性中的作用提供形态学基础。方法选取健康红目豚鼠6只，采用免疫组织化学方法，以山羊抗GLAST抗体为标记物，观察正常豚鼠耳蜗中GLAST的表达及分布。结果在正常豚鼠耳蜗的内、外毛细胞，内、外毛细胞周围的支持细胞，螺旋神经节细胞，血管纹边缘细胞和螺旋缘上皮，均有GLAST阳性表达。结论GLAST在正常豚鼠耳蜗内主要分布于内、外毛细胞，内、外毛细胞周围的支持细胞，螺旋神经节细胞、血管纹边缘细胞和螺旋缘上皮，其功能尚需进一步的研究。     

大鼠耳蜗L-型电压门控钙通道亚型的表达

目的 :研究大鼠耳蜗毛细胞电压门控性钙通道 (VGCC)mRNA的表达及其意义。方法 :利用RT PCR和原位杂交技术检测了L 型VGCC的 4种亚单位在大鼠耳蜗毛细胞的表达。 结果 :以耳蜗基底膜中提取的总RNA为模板可以检测到α1C和α1D钙通道的表达 ,原位杂交显示内、外毛细胞被特异性的探针标记。结论 :耳蜗Corti器表达的VGCC主要是α1C和α1D亚型     

豚鼠耳蜗毛细胞丝状肌动蛋白表达

目的研究正常生理状态下丝状肌动蛋白(F-actin)的结构特征和分布规律。方法应用免疫细胞化学方法,采用单克隆抗体及免疫荧光标记技术,借助荧光显微镜和激光扫描共聚焦显微镜,逐层观察耳蜗毛细胞骨架蛋白-丝状肌动蛋白的分布特点。结果在连续的光学切片上,可以看到静纤毛、表皮板和外毛细胞(outerhaircells,OHCs)的周围环都有明亮的鬼笔环肽染色。除基底转外,其余各转皮板下网络(infracuticularnetwork,ICN)均有鬼笔环肽显色,外毛细胞侧壁着色亮度自基底转到顶转逐渐减弱。内、外柱细胞和Deiters细胞染色明亮,其中耳蜗各转外柱细胞头板的显色亮度都强于OHCs。结论豚鼠耳蜗OHCs中F-actin的结构和分布存在差异,内毛细胞(innerhaircells,IHCs)的结构和分布无差异,表明局部结构的梯度决定局部功能的差异。     

CBA小鼠内耳感觉上皮的参考数据

目的测量成年CBA小鼠耳蜗和前庭的有关数据,为内耳感受器定量分析提供参考依据。方法将6只出生后3个月左右的成年CBA小鼠(12耳)的耳蜗和前庭各终器取出并制备成全耳蜗基底膜铺片和全前庭终器铺片。测量全耳蜗基底膜的总长度,以及基底膜和Corti器在耳蜗不同部位的宽度。观察并记录全耳蜗毛细胞的总数和基底膜上不同区间的毛细胞密度。观察并记录椭圆囊斑和球囊斑毛细胞的总数及其微纹区和周边区的毛细胞密度,记录壶腹嵴上的毛细胞密度。结果正常成年CBA小鼠的耳蜗基底膜长度为(5.76±0.196)毫米(平均数±标准差,下同),基底膜的宽度在耳蜗底部距起始端约1.5毫米处为(339.1±9.87)微米,在耳蜗中部距起始端约3毫米处为(304.5±11.82)微米,在耳蜗顶部距起始端约5毫米处为(300.1±7.22)微米,说明小鼠耳蜗基底膜的宽度从底回到顶回逐渐变窄。Corti器的宽度在耳蜗底部距起始端1.5毫米处为(37.80±2.24)微米,在耳蜗中部距起始端约3毫米处为(45.00±2.67)微米,在耳蜗顶部距起始端约5毫米处为(52.20±3.16)微米,可见Corti器的宽度从底回到顶回逐渐变宽。CBA小鼠全耳蜗毛细胞的总数为(3116.41±151.91)个,其中内毛细胞总数为(680.67±17.50)个,而外毛细胞的总数是(2435.8±143.46)个。耳蜗内、外毛细胞的平均密度为(541.1±9.36)个/毫米,其中内毛细胞的平均密度为(118.3±2.68)个/毫米,外毛细胞的平均密度为(422.8±11.87)个/毫米,耳蜗毛细胞在耳蜗基底膜上不同区间的毛细胞密度无明显差异(P>0.05)。小鼠椭圆囊斑上的毛细胞总数为(3300±177.51)个,球囊斑上的毛细胞总数为(3045±361.57)个。前庭球囊斑和椭圆囊斑微纹区和周边区的毛细胞密度基本相同(P>0.05),两个囊斑微纹区的平均毛细胞密度为(40.2±6.59)个/0.0025mm2,两个囊斑周边区的平均毛细胞密度为(53.2±7.18)个/0.0025mm2,可见囊斑微纹区的毛细胞密度低于周边区。尽管小鼠上半规管和后半规管壶腹嵴的毛细胞区被位于嵴中央的上皮细胞分隔为两个区域,但三个壶腹嵴上的毛细胞密度基本相同,其平均密度为(44.7±7.15)个/0.0025mm2。结论本实验所得CBA小鼠耳蜗和前庭测量数据,为进一步定量观察CBA小鼠内耳病理学改变提供了重要的参考依据。     

卡那霉素耳中毒后豚鼠耳蜗热休克蛋白的表达

目的　观察卡那霉素对热休克蛋白 70 (HSP70 )在豚鼠耳蜗中表达的影响。方法　取听力正常豚鼠随机分为实验组和对照组各 5只 ,分别给予 2 5 0mg·kg-1·d-1卡那霉素和生理盐水肌注 ,10天后处死。左耳铺片 ,右耳石蜡包埋切片。用免疫组织化学方法检测各组石蜡切片HSP70表达情况 ,通过计算机图像分析系统分析HSP70表达强度。结果　对照组中Corti器、血管纹、螺旋韧带、内螺旋缘、螺旋神经节HSP70表达呈弱阳性 ;耳蜗铺片显示内 ,外毛细胞正常。实验组中Corti器、血管纹、螺旋韧带、内螺旋缘HSP70表达呈强阳性 ,而在螺旋神经节呈弱阳性 ;耳蜗铺片显示外毛细胞大部分缺损。结论　卡那霉素能够诱导HSP70在豚鼠耳蜗中表达     

声音在耳内的信号转导及其分子生物学机制(2)

1．3耳蜗的机械一电转换机制 1．3．1柯蒂器的机械一电转换作用柯蒂器是耳蜗内的声音感受器，包括毛细胞和各种支持细胞，它们乘载于基底膜之上，并沿着基底膜的长轴进行延伸。柯蒂器中的大多数细胞功能不清，但已明确内、外毛细胞功能主要是感受声音刺激的。基底膜本身的机械特性及其与毛细胞、听神经的有序组合排列，使基底膜的任何位置都对应某一特定频率，     

头面部常规^60钴照射及顺铂应用对豚鼠耳蜗的影响

将实验豚鼠分成60钴70Gy照射组，60钴50Gy照射组，顺铂治疗组，60钴50Gy照射加顺钱治疗组，对照组，共5组每组9耳，顺铂腹腔注射2mg/kg/次，共10次，用电瓜在测听仪分别在实验前、60钴照射后或应用顺铂后10周测定ABR阈值，对全耳蜗铺片基底膜上的内、外毛细胞及柱细胞缺损九进行定量观察计数。结果各组实验耳在ABR阈值测定上均无显著性差异。在基底膜内、外毛细胞及柱细胞缺损方面，提示随着放射剂量的增大，耳蜗毛细胞的损伤也随之增加。应用顺铂后可加重放射对耳蜗的损害，但按临床常规应用顺铂的剂量则对耳蜗是安全的。     

离体培养时bFGF对顺铂耳蜗毒性的拮抗作用

目的 研究不同浓度的顺铂对耳蜗基底膜毛细胞的损伤、不同浓度的bFGF对顺铂耳蜗基底膜毛细胞损伤的保护作用以及caspase-9的表达。方法 对耳蜗基 底膜进行离体培养,用荧光染色方法对毛细胞数量和caspase-9的表达进行观察。结果 在不同浓度中,15μg/ml顺铂对基底膜毛细胞损伤最大;bFGF浓度≥100ng/ml时,对顺铂所致的基底膜毛细胞损伤具有良好的拮抗作用。结论 顺铂对耳蜗基底膜上毛细胞的损伤具有剂量依赖性; bFGF拮抗顺铂所致的耳蜗基底膜毛细胞的损伤;caspase-9的表达与bFGF对顺铂耳蜗毒性的拮抗作用相关。     

Ultrastructural damage in cochleas used for studies of basilar membrane mechanics

Cat cochleas used for interferometric studies of basilar membrane mechanics were examined with the electron microscope. The structures most severely damaged in the experimental cochleas are the outer hair cells and the radial afferent fibers to the inner hair cells. Since the basilar membrane and other supporting structures appear to be normal, mechanical changes observed in the experimental cochleas are most probably due to outer hair cell damage. Individual animals with varying degrees of damage showed large differences in the frequency of basilar membrane resonance at the same place in the cochlea. Shifts in tuning of this magnitude could occur as a consequence of hair cell damage only if the stiffness of the stereocilia and associated structures was greater initially than the stiffness of the basilar membrane and gradually decreased with damage. The present series of observations, therefore, suggest that the stiffness of the outer hair cell stereocilia determines basilar membrane tuning.     

Noise-induced inner ear damage in newborn and adult guinea pigs

Two-day (Group A), eight-day (Group B), and eight-month (Group C) old guinea pigs were exposed to 30 continuous hours of white noise at 119–120 db SPL. One month later pathology of the organ of Corti was evaluated and quantitated by use of the surface preparation technique. Percent cell damage was determined for outer hair, inner hair, outer pillar, and inner pillar cells at each of the four turns of the cochlea and for the cochlea as a whole. Comparisons of pathology of each cell type were made between groups. Mean percent outer hair cell damage per cochlea (± 1 S.E.) was 23.72 ± 3.69 for Group A, 36.98 ± 5.76 for Group B, and 7.24 ± 1.75 for Group C. There was no significant difference in outer hair cell damage between Groups A and B. Outer hair cells of Group A were significantly more damaged than those of Group C when damage in the cochlea as a whole was considered due to significantly greater damage in Group A at three and one half turns; likewise, outer hair cells of Group B were significantly more damaged than those of Group C when damage in the cochlea as a whole was considered due to significantly greater damage in Group B at two and one half and at three and one half turns. A similar effect was observed in terms of pathology of inner hair cells and pillar cells: there was a trend toward increased damage in animals of Groups A and B compared with C. Group C showed no outer or inner pillar cell damage, and only one of six animals had alterations in inner hair cells. In contrast, outer and inner pillar cells were damaged in Groups A and B, and four of six animals of Group A and six of eight of Group B showed inner hair cell damage. Recent electrophysiological and audiometric studies are discussed which, with the results of the present study, indicate greater susceptibility of young cochleas when compared with older cochleas, to noise-induced physiological and pathological alterations. It would seem medically prudent to take special precautions to avoid exposing newborns to excessive noise.     

蛋氨酸对离体培养小鼠耳蜗毛细胞顺铂耳毒性的拮抗作用

目的 在培养基中加入顺铂,建立离体培养小鼠耳蜗毛细胞的顺铂损害模型,探讨蛋氨酸对毛细胞的保护作用.方法 32只出生后2 d昆明小鼠,取出耳蜗基底膜,分为4组,每组16个样本,分别用无血清培养液、含顺铂的无血清培养液、含顺铂+蛋氨酸的无血清培养液以及含蛋氨酸的无血清培养液进行离体培养.采用肌球蛋白Ⅵ(myosinⅥ)免疫荧光染色,通过激光共聚焦显微镜、光镜、毛细胞计数等方法,观察蛋氨酸对顺铂引起的耳蜗毛细胞损伤的保护作用.结果 对照组和蛋氨酸组基底膜内、外毛细胞未见损伤缺失;顺铂组耳蜗基底膜内、外毛细胞均有不同程度的损伤,与对照组和蛋氨酸组比较,差异均具有统计学意义(P值均＜0.05);顺铂+蛋氨酸组基底膜内、外毛细胞的损伤程度与顺铂组相比明显减轻,差异具有有统计学意义(t内毛细胞=3.929、t外毛细胞=8.582,P值均＜0.05).结论 顺铂能损伤离体培养的小鼠耳蜗基底膜毛细胞,蛋氨酸可以在一定程度上拮抗顺铂对毛细胞的损伤.

Abstract：

Objective To establish an in vitro model of mouse cochlear basilar membrane impairment using cisplatin, and observe the protective effect of methionine on the hair cells. Methods The cochlear basilar membrane samples of thirty two Kunming mice were harvested on the 2nd day after birth and randomly divided into four groups. Each group had 16 samples. Overnight preincubation the cochlear organ followed by appropriate treatment respectively as follows: the serum-free culture medium, the serum-free culture medium with methionine and cisplatin, the cisplatinum-containing serum-free culture medium, and the methionine-containing serum-free culture medium. The protective effect of methionine for injury of cochlea hair cells induced by cisplatin was observed by myosin-Ⅵ immunofluorescence, lightmicroscop,laser confocal scanning microscope and hair cells counting. Results The outer hair cells(OHC) and inner hair cells(IHC) of control group and methionine group were not damaged. The outer and inner hair cells of cisplatin group were damaged in various degree, and had remarkable difference compared with control group and methionine group(P ＜ 0. 05). The outer hair cells and inner hair cells of cisplatin + methionine group were damaged less than the cisplatin group with remarkable difference (tIHC = 3. 929, tOHC = 8. 582, P ＜0. 05). Conclusions Cisplatinum could damage the cochlear hair cells of the basal membrane in Kunming mice. Methionine might protect against cisplatin's damage on the cochlear hair cells.     

Acoustic lesions in the mammalian cochlea: implications for the spatial distribution of the 'active process'.

The spatial contribution of mechanically active hair cells to tuning and sensitivity at a single point in the mammalian cochlea has been investigated in the basal turn of the guinea pig cochlea. Following the destruction of outer hair cells with acoustic overstimulation it was possible to record apparently normal tuning and sensitivity from spiral ganglion neurones innervating inner hair cells located on the apical edges of substantial lesions. The distance between the recording site, where neurones showed normal sensitivity, and areas of the cochlea showing 60-100% of the outer hair cells either damaged or missing varied between 0.2 and 1.3 mm which incorporates approximately 70 to 450 outer hair cells. In one animal neurones that demonstrated normal sensitivity were recorded within 0.2 mm of a lesion where 67% of the outer hair cells were either missing or showed severe damage to their stereocilia and within 0.5 mm of areas of the organ of Corti showing damage to 97% of the outer hair cells. This distance includes approximately 50 inner hair cells or 180 outer hair cells. The location of these neurones, whose sharp tuning presumably mirrors basilar membrane mechanics, suggests that a substantial proportion of point tuning in the cochlea may be derived over a distance of less than 0.5 mm and involve fewer than 200 active outer hair cells.     

Immunohistochemical localization of urea transporters A and B in the rat cochlea

Urea is present in the inner ear, and when it is administered, induces rapid changes in the volume and osmolality of the inner ear fluid. However, the regulating mechanisms are unknown. Two groups of urea transporters (UTs), the renal urea transporter (UT-A) and the erythrocyte urea transporter (UT-B) have been cloned recently. The aims of the current study were to investigate the cellular localization of UTs in the cochlea of male Sprague-Dawley rats by immunohistochemistry. Both UT-A1 and UT-B were expressed in the inner and outer pillar cells, inner and outer hair cells, Boettcher's cells, and Deiters' cells in the organ of Corti. Immunoreactivity for UT-A3 was localized only in the mesothelial cells underlying the basilar membrane. In the stria vascularis, UT-A1 was expressed only in the marginal cells, whereas UT-B was expressed only in the basal cells. In the spiral ganglion, most cells had strong UT-A1 immunoreactivity whereas UT-B was not expressed. In the spiral limbus, UT-B was expressed in the interdental cells whereas UT-A was not expressed. In the crista ampullaris, UT-A1 was expressed in the dark cells, and UT-B expressed in the apical membrane of supporting cells in the neuroepithelium. The distribution of UT-A and UT-B in the inner ear suggests that the cells that surround the inner ear fluids may be involved in urea transport and thus play an important role in fluid homeostasis in the inner ear. The expression of UT-A and UT-B in the hair cells raises the possibility that UTs may be involved in volume regulation in these cells and mediate hair cell turgor.     

Phase opposition between inner and outer hair cells and auditory sound analysis.

Recordings of single-unit responses in the auditory nerve of normal and kanamycin-treated Mongolian gerbils indicate that inner and outer hair cells of the cochlea interact in phase opposition. After kanamycin treatment, the firing rate in some fibers is increased during the basilar membrane motion toward scala vestibuli, in others, during its motion towards scala tympani. Because of statistical correlation with anatomical changes and characteristic time patterns, the first response polarity is associated with inner hair cells, the second, with outer hair cells. It is shown that normal responses can be reconstructed from the two kinds of responses seen after kanamycin treatment. The phase opposition between inner and outer hair cells, in connection with the expected effect of spiral fibers, provides an explanation for neural sharpening of mechanical filter action in the cochlea.     

Phase opposition between inner and outer hair cells and auditory sound analysis

Recordings of single-unit responses in the auditory nerve of normal and kanamycin-treated Mongolian gerbils indicate that inner and outer hair cells of the cochlea interact in phase opposition. After kanamycin treatment, the firing rate in some fibers is increased during the basilar membrane motion toward scaly vestibule, in others, during its motion towards scaly tympani. Because of statistical correlation with anatomical changes and characteristic time patterns, the first response polarity is associated with inner hair cells, the second, with outer hair cells. It is shown that normal responses can be reconstructed from the two kinds of responses seen after kanamycin treatment. The phase opposition between inner and outer hair cells, in connection with the expected effect of spiral fibers, provides an explanation for neural sharpening of mechanical filter action in the cochlea.     

Immunoelectron microscopic localization of nitric oxide synthase III in the guinea pig organ of Corti

Nitric oxide synthase III (NOS III) was identified in the guinea pig cochlea on an ultrastructural level using a post-embedding immunolabeling procedure. Ultrathin sections of London Resin (LR) White-embedded specimens were incubated with various concentrations of a commercially available antibody to NOS III and the immunoreactivity visualized by a gold-labeled secondary antibody. Analysis of ultrathin sections of the organ of Corti in the second turn of the cochlea showed that NOS III could be localized in the endothelial cells of the blood vessels under the basilar membrane, which was comparable to its location in similar cells types in various biological systems. Besides this, NOS III was also found in the cytoplasm and in the nuclei of inner and outer hair cells. Immunoreactivity was not distributed homogeneously within receptor cells. Numerous gold particles could be identified at the border of the cuticular plates, in the middle parts of the stereocilia and in the cytoplasm. Gold-labeled anti-NOS III antibodies in these sites were seen mostly on the cytoplasmic side of the submembranous cisterns in the vicinity of mitochondria and in the central parts of the hair cells, whereas the cisterns were nearly free from any immunoreactivity. NOS III was also detected in the efferent and afferent nerve endings that were located at the basal and basolateral side of the outer hair cells. Some immunoreactivity was visible in different nerve fibers of the inner and outer spiral tunnels. Besides this, gold-labeled antibodies were also present in the cuticular plate of inner and outer pillar cells, in the cytoskeletal elements located in the apical parts of Deiters cells, forming the lamina reticularis, and in the cytoskeletal-containing region of the cytoplasm of those Deiters cells located at the basal side of the outer hair cells. The role of the NOS III immunoreactivity identified in the organ of Corti was consistent with respect to hair cell and tissue modulation. Received: 24 September 1997 / Accepted: 26 June 1998     

Postnatal development of the organ of Corti in the wild house mouse, laboratory mouse, and their hybrid

Length of the basilar membrane, number and distribution of cochlear receptors, and the width of the triad of outer hair cells were analyzed in the course of the postnatal development and in adult individuals in wild and laboratory house mice and in hybrids of these species. While in newborn animals the triad of outer hair cells was wide at the base and narrow at the apex, the opposite was true for adult animals. The parameter decreased at the base and increased at the apex during postnatal development. The center of differentiation of (the reticular lamina of) the organ of Corti was localized at 40-50% of the basilar membrane length from the base and corresponded to the region with the maximum density of inner hair cells. The reticular lamina in the apical half of the cochlea matured earlier than in the basal half. Distribution of receptors did not change after birth. The shortest basilar membrane and the slowest rate of maturation were found in wild mice. Hybrids had the longest basilar membrane and the highest rate of maturation. These facts are considered an effect of heterosis.     

新生小鼠耳蜗基底膜体外培养的实验研究

目的建立可靠的新生小鼠离体耳蜗基底膜的培养方法,为内耳的研究提供新的条件和模型。方法在显微镜下完整分离出新生1～5 d小鼠的耳蜗基底膜组织,采用组织贴壁法在无血清培养基中进行培养,免疫荧光法检测新生小鼠离体耳蜗基底膜培养组织中毛细胞及螺旋神经元的生长状态。结果新生小鼠耳蜗基底膜离体培养24 h后,显微镜下观察可见基底膜贴壁生长良好,外周有新生上皮细胞和成纤维细胞长出;高倍显微镜下可见耳蜗内外毛细胞和支持细胞等结构;免疫荧光法检测可见毛细胞和螺旋神经元生长良好,并能保持较长一段时间。结论组织贴壁法无血清培养新生小鼠离体耳蜗基底膜是一种理想的耳科实验造模方法。