一氧化氮合酶和心钠素在豚鼠耳蜗的分布

目的 观察豚鼠耳蜗局部心钠素（atral natruretc peptde，ANP）和一氧化氮合酶（nitric oxide synthase，NOS）免疫组化反应产物的分布，为研究ANP和NOS在豚鼠耳蜗局部血流、淋巴以及神经调节中的相互作用提供形态学依据。方法 采用免疫组织化学双标法检测ANP和NOS在正常豚鼠耳蜗的分布特征。结果 在耳蜗各转螺旋动脉和血管纹．螺旋缘、螺旋韧带和Corti器显示双阳性染色，螺旋神经节细胞及囊斑神经上皮细胞膜及轴突NOS阳性染色，胞质ANP阳性染色；盖膜、前庭膜阴性染色。结论 ANP和NOS在内耳血 流调节，内、外淋巴平衡调节以及神经信号传递等方面可能具有重要作用，二者之间可能存在密切的相互作用机制，其分布特点与功能密切相关。     

快速老化小鼠的听功能和耳蜗螺旋神经元的增龄性变化

目的探讨快速老化小鼠听觉功能和耳蜗螺旋神经元的增龄性变化。方法选取1、3、5、7、9月龄的快速老化小鼠亚系1( Senescence accelerated mouse/prone 1, SAMP 1)作为实验组，而同龄抗快速老化小鼠亚系1(Senescence accelerated mouse/resistance 1, SAMR 1) 作为SAMP 1的正常对照组。分别观察其8kHz短纯音听觉脑干反应阈值、耳蜗螺旋神经节细胞透射电镜形态学、末端脱氧核苷酸转移酶介导的dUTP原位切口末端标记［terminal deoxynucleotidyl transferase(TdT) dUTP nick end labeling］ TUNEL免疫组化染色等方面的增龄性变化。结果① 听功能检测。第7、9个月龄SAMP 1小鼠跟同龄SAMR 1小鼠比较听觉脑干反应阈值差异有统计学意义；② 耳蜗螺旋神经节细胞形态学检测。第7、9个月龄SAMP 1小鼠可见螺旋神经元凋亡，而同龄SAMR 1小鼠罕见螺旋神经元凋亡；③ 耳蜗中轴位切片TUNEL染色。第7个月龄SAMR 1小鼠SGN细胞核基本上不着色［TUNEL染色阳性率为（2.27±2.43）%］，第7个月龄SAMP 1小鼠部分SGN胞核着色［染色阳性率为（11.36±4.96）%］，两者的染色阳性率差异有统计学意义。结论SAMP 1小鼠随月龄增长耳蜗螺旋神经元凋亡、听功能减退，7月龄SAMP 1小鼠即出现明显的听功能老化特征，可作为老年聋动物模型用于耳聋的相关研究。     

降钙素基因相关肽在豚鼠耳蜗中的分布

目的：观察降钙素基因相关肽(CGRP)在成年豚鼠耳蜗中的分布。方法：采用免疫组织化学，光镜观察的方法，对CGRP在豚鼠耳蜗中的分布进行研究。结果：CGRP阳性反应物分布于螺旋神经元．骨螺旋板神经孔，内毛细胞、外毛细胞与外支持细胞交界区，螺旋韧带血管纹。结论：CGRP广泛分布于豚鼠耳蜗，是耳蜗传出神经系统重要的神经递质或神经凋质，CGRP可能通过调节螺旋神经元、毛细胞和支持细胞等影响听功能．也可能影响耳蜗的血流。     

大鼠单侧耳蜗损毁后下丘r-氨基丁酸及其神经元的变化

目的：研究大鼠单侧耳蜗损毁前后不同时期，下丘中r-氨基丁酸（gamma-aminobutyric acid，GABA）含量及其阳性神经元的分布变化，初步探讨去传入损伤后GABA在听觉中枢重组中的作用和意义。方法：健康SD大鼠随机分为4组：正常组和单侧耳蜗损毁后1周、2周及1个月组。于规定时间内检测并比较耳蜗损毁前后GABA含量及其阳性神经元的数量。结果：与正常组相比，损毁后1周，下丘中GABA含量及其神经元数量明显下降，差异有统计学意义（P〈0．05）；术后2周，下丘中GABA含量及其神经元数量稍上升但仍低于正常组（P〈0．05）；至术后1个月，下丘中GABA含量及其神经元数量上升，与正常组比较差异均无统计学意义（P〉0．05）。结论：单侧耳蜗损毁后，GABA含量及其阳性神经元数量在下丘中呈一明显的动态变化过程，说明GA—BA作为一种神经递质参与了耳蜗毁损后听功能的重组过程，提示GABA在单侧耳蜗损毁后听觉中枢的重组过程中可能起重要作用。     

腱糖蛋白-W在不同发育阶段C57BL/6小鼠耳蜗中的表达

目的研究Tnn基因编码的腱糖蛋白-W(tenascin-W,TN-W)在出生后不同发育阶段小鼠耳蜗内的表达,初步探讨tenascin-W在听觉系统中的功能。方法以出生后(postnatal day,P)1、3、14、28天(P1、P3、P14、P28)各6只及出生后7天(P7)9只C57BL/6小鼠作为研究对象,通过免疫荧光标记观察tenascin-W在耳蜗中的表达及定位,运用实时荧光定量PCR(real-time quantitative PCR,RT-qPCR)检测各发育阶段小鼠耳蜗中Tnn mRNA相对表达水平,Western blot法检测tenascin-W在小鼠耳蜗中的表达。结果免疫荧光标记显示tenascin-W在P1、P3、P7、P14、P28小鼠耳蜗中均有表达。在P1、P3、P7小鼠耳蜗螺旋神经节、Corti器中均有表达,在P14、P28小鼠仅在螺旋神经节高表达,在Corti器中不表达,在各发育阶段小鼠耳蜗血管纹均有表达;共染显示其与Ⅲ型β-tubulin共定位在螺旋神经节神经元胞体的胞浆中。RT-qPCR显示Tnn mRNA在P7小鼠耳蜗相对表达量最高,Western blot法检测到tenascin-W在P7小鼠耳蜗中有表达。结论Tenascin-W在小鼠耳蜗各发育阶段均有表达,在P7表达量最高,且主要定位于螺旋神经节神经元,提示该蛋白可能影响耳蜗螺旋神经元发育及功能,对小鼠正常听觉的维持发挥重要作用。     

前庭学

20050401脉鼠耳蜗和内淋巴囊水通道蛋白的表达/钟时勋…//听力学及言语疾病杂志.2004,12(5).337～339目的:研究脉鼠耳蜗和内淋巴囊组织中水通道蛋白(AQP)不同亚型的定位表达及其意义。方法:用兔抗大鼠AQP1、AQP2、AQP3、AQP4的多克隆抗体,采用免疫组化SP法分别检测相应AQP蛋白亚型在豚鼠耳蜗和内淋巴囊组织中的表达模式。结果:在耳蜗组织中,AQP1、4广泛分布于耳蜗的各个区域,如血管纹、螺旋韧带、Corit器、螺旋缘、螺旋神经节等,AQP3除了在血管纹表达呈弱阳性外,其余区域的表达与AQP1和AQP4相似,AQP2则仅表达于Reissner膜。…     

斯里兰卡肉桂碱受体在不同鼠龄大鼠耳蜗中的表达差异

目的 研究不同鼠龄大鼠耳蜗内斯里兰卡肉桂碱受体(ryanodine receptor,RyR)的差异表达.探讨RyR表达与耳蜗发育成熟的关系.方法 分别选取出生后1天(P1)、5天(P5)、10天(P10)、14天(P14)、28天(P28)以及成年SD大鼠(＞2月龄)各5只耳蜗作冰冻切片.运用免疫荧光的方法 ,比较各组大鼠耳蜗组织RyR的表达差异.结果 P1组和P5组大鼠耳蜗Corti器内RyR表达不明显,P10组出现的RyR染色均匀,而P14组大鼠耳蜗Corti器内RyR的表达出现明显特征性变化,毛细胞突触区RyR强表达,而支持细胞内的表达相对较为广泛.大鼠出生后耳蜗螺旋神经元内RyR的表达由广泛的胞内表达,逐渐趋近细胞膜突触区.结论 RyR在大鼠出生后14天表达基本成熟,与耳蜗的发育成熟基本保持一致.感觉毛细胞和螺旋神经元的RyR表达可能与神经传递等功能相关.在发育早期的螺旋神经元细胞中RyR的广泛表达,可能参与了螺旋神经元发育成熟中的细胞凋亡过程.     

颈上神经节切除对豚鼠耳蜗血流及听性脑干反应阈的影响

目的研究豚鼠颈交感神经节对耳蜗血流及听觉生理功能的调节作用。方法在正常豚鼠单侧耳蜗螺旋蜗轴动脉局部滴加逆行追踪剂辣根过氧化物酶(horseradishperoxidase,HRP),观察双侧交感颈上神经节、星状神经节内的阳性神经元分布;建立单侧颈上神经节切除模型,观察术后不同时间点双侧耳蜗血流、听性脑干反应的情况;建立单侧颈上神经节切除后噪声性听损伤模型,观察颈上神经节切除对噪声损伤导致的听觉阈移是否有保护作用。结果耳蜗螺旋蜗轴动脉局部给予逆行追踪剂后同侧颈上神经节内可见阳性神经元;单侧颈上神经节切除1周后,术侧耳蜗底回血管纹处血流较对侧升高,听性脑干反应阈值无明显变化;颈上神经节切除对噪声导致的听损伤有一定的保护作用。结论交感颈上神经节切除对豚鼠耳蜗血流及听觉生理功能有一定的影响。     

P2嘌呤受体在内耳中的分布特性和功能

在听觉系统中,外源性三磷酸腺苷(ATP)除作为耳蜗活性物质外,还可作为神经递质或调质,参与Corti器内感觉毛细胞及支持细胞的各种生理功能,从而产生一系列效应,调节耳蜗听觉生理功能;ATP的这种作用主要是通过P2嘌呤受体介导的信号传导完成的,现就P2嘌呤受体在内耳的分布特点及介导的信号传导在耳蜗听功能中的生物学作用作一综述.     

大鼠单侧耳蜗损毁对耳蜗核中γ-氨基丁酸能神经元的影响

目的:研究大鼠单侧耳蜗损毁前后耳蜗核中γ-氨基丁酸(GABA)能阳性神经元的分布及数量。方法:应用免疫组织化学方法(SP法)行耳蜗核中GABA能阳性神经元分布的检测。结果:耳蜗核中GABA能神经元的体积较小、数量较多、着色很深。单侧耳蜗毁损后耳蜗核中GABA能阳性神经元的数量:术后1～2周术侧明显低于对侧(均P<0.01);术后3周上升,但仍低于对侧(P<0.05);术后1个月,术侧略低于对侧,但差异无统计学意义(P>0.05)。结论:单侧耳蜗损毁前后,GABA能阳性神经元的分布及数量在耳蜗核中呈一明显的动态变化过程,说明GABA能神经元参与了耳蜗毁损后初级听觉中枢的可塑性变化或功能重组的过程,提示GABA能神经元数量的增减可能为初级听觉中枢的重组所必需。     

Distribution of serotonin immunoreactivity in the spiral ganglion neurons of mouse cochlea

OBJECTIVE: Serotonin (5-hydroxytryptamine, 5-HT) is a neuromodulator/neurotransmitter with multiple biological functions. Spiral ganglion cells in the cochlea are the primary neurons of the afferent system in the auditory transmission. In this study, we used the immunohistochemical technique to investigate the distribution of serotonin in the spiral ganglion of mouse cochlea. MATERIALS AND METHODS: The cochlea tissue of four adult mice was dissected and fixed. The immunohistochemical staining was applied by using goat anti-serotonin polyclonal antibody as primary antibody. Tissue sections were treated with biotin-labeled rabbit anti-goat immunoglobulin G, followed by adding streptavidin-biotin-peroxidase complex. Finally, the sections were stained with 3,3-diaminobenzidine (DAB) solution. RESULTS: The spiral ganglion exhibited pronounced immunoreactivity for serotonin. Specifically, serotonin immunoreactivity was detected in the cytoplasma of spiral ganglion neurons located in Rosenthal's canal of the bony modiolus of mouse cochlea. CONCLUSIONS: Since spiral ganglion neurons are the afferent neurons to the auditory sense organ, our result strongly suggests that serotonin molecule may function as a neuromodulator/neurotransmitter in the peripheral auditory processing.     

Die Wirkung von Fibroblastenwachstumsfaktor-1 (FGF-1) auf Spiralganglienzellen der Säugetiercochlea

Transient expression by hair cells, increasing levels of FGF-1 mRNA in neonatal rat spiral ganglion neurons and strong expression in adulthood, make FGF-1 a candidate to be associated with development and maintenance of the mammalian spiral ganglion. To test this hypothesis, dissociated spiral ganglion cells from 5 day old rats were cultured in the presence of FGF-1 at 100 ng/ml plus heparan sulfate proteoglycans (HSPG) at 500 ng/ml for 72 hours. Spiral ganglion cells incubated with FGF-1/HSPG achieved an average neurite length of 323 microns while control cells gained an average neurite length of 203 microns. The results of this study are consistent with our previous findings in whole spiral ganglion explants (3) where FGF-1 incubation significantly stimulated neurite outgrowth at about the same range. However, stimulation of neurite outgrowth in dissociated spiral ganglion cells suggests that FGF-1 directly binds to FGF receptors on the surface of spiral ganglion neurons and/or neurites instead of acting via intermediate cells such as glia. Since FGF receptor mRNA was found to be expressed only at very low levels in neonatal spiral ganglion neurons (7) it is possible that the receptors are highly localized, perhaps to neurite growth cones. Alternatively, an unknown FGF receptor or splice variant may be expressed in these cells. Adequate FGF-1 application to the human inner ear may stimulate spiral ganglion cell survival and neurite extension after hair cell loss in patients suitable for cochlear implant treatment. By creating a closer contact between spiral ganglion cells and the electrode, FGF-1 might also improve the efficacy of cochlear implants.     

Detection of apoptosis by RT-PCR array in mefloquine-induced cochlear damage

Objective To investigate the occurrence and possible mechanisms of apoptosis in cochlear epithelium and spiral ganglion neurons after mefloquine treatment.Methods We used quantitative RT-PCR apoptosis-...     

Hypoplasia of spiral and Scarpa's ganglion cells in GABA(A) receptor beta(3) subunit knockout mice

This study documents morphologic alterations in the spiral ganglion and Scarpa's ganglion from gamma-aminobutyric acid A (GABA(A)) receptor beta(3) subunit null mutant mice. The ganglion cells of the mutant mice were hypoplastic in hematoylin&eosin-stained sections. Hypoplasia was observed at every location of the spiral ganglion and Scarpa's ganglion except the apical cochlear turn. Calretinin immunostaining demonstrated a selective hypoplasia of calretinin-negative cells at every location of spiral and Scarpa's ganglion cells, while the soma area of calretinin-positive cells was not affected by the gene deletion. Meanwhile, in the spiral ganglion of both wild type and knockout mice, there were apical to basal gradients in the soma size and the proportion of calretinin-positive cells. The absence of statistically significant hypoplasia in hematoylin&eosin sections through the apical turn of the cochlea can be explained by the relatively higher proportion of calretinin-positive ganglion cells, which were unaffected by the gene deletion. These findings suggest that GABA(A) receptor isoforms containing the beta(3) subunit may play an important role in the development and differentiation of non-calyceal terminals of Scarpa's ganglion cells and type II and smaller type I spiral ganglion cells.     

Idiopathic sudden sensorineural hearing loss: temporal bone histopathologic study

We microscopically examined the temporal bones of 12 ears with idiopathic sudden sensorineural hearing loss (iSSNHL), 10 ears with presbycusis, 11 ears with normal hearing, and 8 unaffected contralateral ears of patients with iSSNHL. The degeneration of the spiral ligament, vascular stria, hair cells, dendrites, and apical spiral ganglion cells was greater in ears with iSSNHL than in the other groups. The apical ganglion cells were significantly more affected than the basal ganglion cells, and the spiral ganglion cell loss increased as a function of duration of iSSNHL. Cochlear ossification was found in 1 ear with iSSNHL, and hydrops in 2. These findings suggest a viral rather than a vascular or ruptured inner ear membrane origin for iSSNHL.     

Immunohistochemical localization of histamine receptors in rat cochlea

OBJECTIVE: Histamine may have physiologic functions in the inner ear. The locations of histamine receptors, however, have not yet been identified in the mammalian cochlea. The aim of this study was to investigate the localization of histamine receptor subtypes (H1, H2, and H3 receptors) in rat cochlea. METHODS: Immunohistochemistry was performed with antibodies specific for each of the histamine receptors (H1, H2, and H3). To identify the type I and II spiral ganglion cells in the cochlea, some cryostat sections were double stained with antibodies to both a histamine receptor and neurofilament 200 kD, which predominantly stains type II spiral ganglion cells in the cochlea. RESULTS: All H1, H2, and H3 receptor immunoreactive staining was limited to the spiral ganglion cells of the cochlea. Spiral ganglion cells with positive immunoreactivity to the neurofilament 200 kD antibody were stained only slightly by histamine H1, H2, and H3 receptor antibodies, indicating that histamine receptor immunoreactivity is specific to type I ganglion cells. CONCLUSIONS: These findings indicate that histamine receptors are present in the cochlea and support the hypothesis that histamine plays a physiologic role in the cochlea.     

Expression of endothelin receptor subtypes in the spiral ganglion neurons of the guinea pig

Objective

Endothelin 1 has many biological activities including regulating the functions of auditory system. The present study aimed to investigate the expression of the endothelin receptors in spiral ganglion neurons and its significance in the auditory transmission.

Methods

The cochleae of healthy guinea pigs were fixed, decalcified, embedded in paraffin and serially sectioned. The expression of endothelin receptor subunits, ET receptor A (ET-A) and ET receptor B (ET-B), was examined in the spiral ganglion neurons of guinea pig using immunohistochemical technique.

Results

Different degrees of ET-A and ET-B positive reactivity appeared in all spiral ganglion neurons from the basal turn to the apical turn.

Conclusions

These findings support the suggestion that endothelin via the endothelin receptor may play a physiological role in the spiral ganglion neurons.     

Frequency representation and spiral ganglion cell density in the cochlea of the gerbil Pachyuromys duprasi.

The tonotopic map of the cochlea in the gerbil Pachyuromys duprasi was analysed by local iontophoretic HRP-application into physiologically defined regions of the cochlear nucleus and mapping of subsequent HRP transport patterns in cochlear spiral ganglion cells. Furthermore the spiral ganglion cell density along the cochlear duct was determined. The cochlear tonotopic map was established in the frequency range between 0.6 and 17.5 kHz. These frequencies corresponded to locations between 86 and 3% basilar membrane length (0% = cochlear base). It was found that the slope of the place-frequency map varied with frequency, the maximum slope being found between 1 and 4 kHz. This frequency range corresponds to the frequency range of highest auditory sensitivity as determined from cochlear microphonic recordings (Plassmann et al., 1987). The density of spiral ganglion cells also varied along the cochlear duct. A pronounced maximum (1927 cells/mm) was located at around 70% basilar membrane length, compared to values of 800 cell per mm near the cochlear apex and base. This region of high ganglion cell density also corresponds to the frequency range of highest auditory sensitivity.