豚鼠耳蜗一氧化氮合酶的分布

目的 用组织化学法,通过观察NADPH-黄递酶的活性了解一氧化氮合酶在豚鼠耳蜗内分布。方法 经4％多聚甲醛心脏灌注固定后,取出耳蜗,经3％依地酸脱钙后,作厚10μm冰冻切片,用辅酶Ⅱ孵育液在37℃条件下孵育l小时。结果 发现在耳蜗内、外毛细胞底部与耳蜗神经末梢接头处及毛细血管球内皮细胞有明显NADPH-黄递酶活性,此外在内、外柱细胞、支持细胞、血管纹及螺旋神经节细胞也有NADPH-黄递酶活性反应。结论 NO在维持耳蜗正常神经传导及毛细血管张力中起着重要作用。     

大鼠耳蜗一氧化氮合酶的分布和表达

目的 本实验先用组织化学法，通过观察还原型辅酶Ⅱ－黄递酶（NADPH－黄递酶）的性了解一氧化氮合酶（nitric oxide synthase,NOS）在大鼠耳蜗内分布。再用亲合免疫细胞组织化学技术，研究大鼠耳蜗内神经元型NOS（neuronal NOS,nNOS）与内皮型NOS（endthelial NOS,eNOS）的表达。方法 组化组大鼠耳蜗切片用辅酶Ⅱ孵育液在37℃条件下孵育1小时。免疫组化组大鼠耳蜗切片经消除内源性过氧化物酶，3％山羊正常血清封闭非正常结合点后，用兔抗nNOS抗体、兔抗eNOS抗体，室温下孵60发钟，再用生物素标记的山羊抗兔第二抗体孵育、滴加ABC试剂，以DAB试剂显色。结果 大鼠耳蜗血管球内皮细胞有明显NADPH－黄递酶活性，血管纹及螺旋神经节细胞也有NADPH－黄递酶活性反应。大鼠耳蜗内、外毛细胞、螺旋神经节细胞nNOS、eNOS的表达呈阳性。血管纹细胞处有阳性nNOS、eNOS的表达。耳蜗血管球的内皮细胞无nNOS的表达，但eNOS的表达呈强阳性。结论 由nNOS及eNOS合成的NO在维持耳蜗正常神经传导及耳蜗毛细血管张力和正常血液供应中起着重要作用。     

豚鼠耳蜗一氧化氮合酶异型体的定位

目的研究一氧化氮合酶(NOS)的异型体在豚鼠耳蜗的定位分布,以探讨一氧化氮(NO)在内耳听觉生理和病理生理机制中的作用。方法使用特异性NOS异型体抗体,采用ABC免疫组化染色法,观察NOS异型体在正常豚鼠耳蜗的定位表达。结果NOS Ⅰ主要分布在内骨膜、螺旋神经节的核周体、螺旋韧带和Corti's器的细胞。NOSⅢ是耳蜗的主要NOS异型体免疫染色,其主要免疫染色分布于耳蜗神经、螺旋神经节核周体、螺旋韧带和耳蜗毛细血管球的内皮细胞,也见于Corti's器的细胞和神经纤维。NOS Ⅱ在正常豚鼠耳蜗内不表达。 结论结构型NOS(cNOS)表达在耳蜗的多个部位,表明NO参与内耳的正常生理功能,包括神经突触的神经传导、耳蜗血流的调节和耳蜗的骨代谢。     

豚鼠耳蜗一氧化氮合酶异型体的定位

目的 研究一氧化氮合酶(NOS)的异型体在豚鼠耳蜗的定位分布，以探讨一氧化氮(NO)在内耳听觉生理和病理生理机制中的作用。方法 使用特异性NOS异型体抗体，采用ABC免疫组化染色法，观察NOS异型体在正常豚鼠耳蜗的定位表达。结果 NOS Ⅰ主要分布在内骨膜、螺旋神经节的核周体、螺旋韧带和Corti’s器的细胞。NOS Ⅲ是耳蜗的主要NOS异型体免疫染色，其主要免疫染色分布于耳蜗神经、螺旋神经节核周体、螺旋韧带和耳蜗毛细血管球的内皮细胞，也见于Corti’s器的细胞和神经纤维。NOS Ⅱ在正常豚鼠耳蜗内不表达。结论 结构型NOS(cNOS)表达在耳蜗的多个部位，表明NO参与内耳的正常生理功能，包括神经突触的神经传导、耳蜗血流的调节和耳蜗的骨代谢。     

诱生型一氧化氮合酶在顺铂所致豚鼠耳蜗损伤中的表达

目的：检测诱生型一氧化氮合酶（iNOS）在顺铂所致豚鼠耳蜗损伤中的表达。方法：实验组豚鼠腹腔注射顺铂造成耳蜗损伤，对照组豚鼠腹腔注射等量生理盐水。用免疫组织化学的方法检测iNOS在耳蜗中的表达。结果：iNOS在实验组耳蜗的表达呈阳性，在对照组耳蜗的表达呈阴性。结论：iNOS在顺铂损伤耳蜗中呈阳性表达，iNOS催化产生大量NO而致耳蜗损伤。     

心钠素在豚鼠耳蜗蜗管外壁的分布

采用免疫组织化学ＡＢＣ法检测心钠素在正常豚鼠耳蜗外壁的分布。结果表明，在耳蜗１－４回蜗管外壁的血管纹，螺旋凸，外沟细胞及前庭附中间阶外壁的螺旋韧带均发现有ＡＮＰ反应阳性产物，即有ＡＮＰ存在；而鼓阶外壁的螺旋韧带ＡＮＰ－ＩＲ为阴性，即无ＡＮＰ存在。提示耳蜗蜗管外壁ＡＮＰ对内耳淋巴液的生成可能起着重要的作用；虽然螺旋韧带组织结构相同，但由于ＡＮＰ的分布不同其生理功能则各异。     

噪声刺激对耳蜗一氧化氮合酶的影响

目的：探讨一氧化氮（ＮＯ）在噪声性聋发病中的作用。方法：用中高频连续稳态噪声制作噪声性聋的动物模型,用ＮＡＤＰＨ－黄递酶组织化学、原位杂效和Ｎｏｒｔｈｅｒｎ印迹法,观察噪声刺激对耳蜗一氧化氮合酶（ＮＯＳ）表达的影响。结果：组织化学法显示ＮＯＳ主要分布于内外毛细胞、螺旋神经节细胞和血管纹边缘细胞;原位杂效法发现ＮＯＳｍＲＮＡ在内外毛细胞、螺旋神经节细胞胞浆内均可见阳性染色,但血管纹边缘细胞无阳性染色     

白噪声对豚鼠耳蜗核一氧化氮合酶活性的影响

采用硫辛酰胺脱氢酶组织化学方法及图象分析技术，研究白噪声暴露后豚鼠耳蜗核一氧化氮合酶（ＮＯＳ）神经元及ＮＯＳ活性的变化与听阈的关系，探讨豚鼠耳蜗核ＮＯＳ神经元在白噪声损伤过程中可能的作用。结果表明，白噪声暴露后耳蜗核ＮＯＳ阳性神经元的数量及染色强度明显增加，２周达到高峰，３￣４周持续高表达，至５周有所恢复，仍高于正常水平。白噪声暴露后７ｄ以内，耳蜗核ＮＯＳ活性与ＡＢＲ阈值有分离现象，７ｄ后，ＮＯＳ     

雏鸡耳蜗中的一氧化氮合成酶分布

应用冰冻切片组织化学技术，以还原型尼克酰胺腺嘌呤二核苷酸磷酸-黄递酶特异性地确定一氧化氮合成酶（NOS）在小鸡耳蜗中存在，观察其分布情况，发现听毛细胞底部颗粒较集中，染色深，毛细胞周围亦有散在颗粒，基底乳头近端与远端染色强弱相似。阳性反应神经纤维连接毛细胞底部。螺旋神经节细胞胞浆中有大量的蓝色颗粒，细胞核无着色，这些细胞大小均匀，呈圆形或椭圆形，周围有多量阳性神经纤维，提示可能为神经性NOS。血管盖内皮细胞胞浆中酶活性较强。对这些分布特点和意义进行了讨论。     

Lipopolysaccharide-induced expression of nitric oxide synthase II in the guinea pig vestibular end organ

The purpose of the investigation was to ascertain whether inoculation of bacterial lipopolysaccharide (LPS) into the vestibular organ of the guinea pig might induce formation of nitric oxide synthase (NOS) II. Forty-eight hours after the animals were injected with 1 mg transtympanic LPS, varying degrees of impaired caloric responses were observed with similar degeneration of vestibular hair cells. These effects could be blocked with N-nitro-l-arginine methylester, a competitive inhibitor of NOS. Findings suggested that NOS II, which was not normally detectable in the guinea pig vestibular organ but was present following inoculation of LPS, produced the nitric oxide as the toxic factor causing cell damage. If true, LPS may represent a reproducible method for studying the vestibular pathogenesis of inner ear disease. Received: 22 July 1997 / Accepted: 18 September 1997     

Lipopolysaccharide-induced expression of inducible nitric oxide synthase in the guinea pig organ of Corti

The purpose of the investigation was to ascertain whether inoculation of bacterial lipopolysaccharide (LPS) into the cochlea of the guinea pig could elicit formation of inducible nitric oxide synthase (iNOS). Immunohistochemical study revealed that immunoreactivity to iNOS was seen below outer hair cells representing nerve fibers and synaptic nerve endings. iNOS-staining could also be observed in phalangeal dendrites of Deiter’s cells pointing to the cuticular membrane, Hensen’s cells and on stria vascularis 48 h after inoculation with LPS. Immunohistochemical investigation with a specific anti-nitrotyrosine antibody also revealed intense immunoreactivity identical to that of iNOS, suggesting formation of peroxynitrite in the organ of Corti by the reaction of NO with O₂⁻. On the basis of these findings, it can be concluded that NO together with O₂⁻, which form the more reactive peroxynitrite, are the most important pathogenic agents in LPS-induced damage of cochlea in the guinea pig.     

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     

Electron microscopic localization of nitric oxide I synthase in the organ of Corti of the guinea pig

Nitric oxide synthase (NOS) activity has been detected previously in the mammalian cochlea at a light microscopic level. Here we present results of electron microscopic analysis for post-embedding immunoreactivity of neural-type NOS I in the cochlea of the guinea pig. Strong enzyme immunoreactivity was identified in the cytoplasm of inner and outer hair cells. Gold-labeled NOS I antibodies were mainly located in electron-dense areas of the cytoplasm, whereas electron-lucent regions of the receptor cells were nearly free from any immunoreactivity. In both types of hair cells anti-NOS I antibodies were also visible in the cuticular plates, hair bundles and nuclei. Further ultrastructural analysis revealed that the submembranous cisternae of the outer hair cells were nearly free from any reaction product, demonstrating that the whole cytoplasm of this hair cell was not immunoreactive. Other NOS I immunoreactivity was identified in the cuticular plates of the inner and outer pillar cells and in the cytoskeletal elements located in the apical parts of Deiter cells, forming the lamina reticularis or in cytoskeletal-containing regions in basal Deiter cells. Anti-NOS antibodies were visible in the nuclei of various cell types. Our findings suggest that nitric oxide produced by NO I synthase in the organ of Corti may act as a modulator of hair cell physiology during the processes of signal transduction with frequence selectivity.     

Ischemia-reperfusion injury of the cochlea: effects of an iron chelator and nitric oxide synthase inhibitors

Release of free iron from cellular stores and activation of nitric oxide synthase (NOS) has been implicated in a wide variety of cochlear injuries. In order to evaluate the effects of deferoxamine (a iron chelator), 3-bromo-7-nitroindazole (a relatively selective neuronal NOS (nNOS) inhibitor) or aminoguanidine (a relatively selective inducible NOS (iNOS) inhibitor) on the post-ischemic cochlear dysfunction, albino guinea pigs were subjected to 30 min ischemia, and the threshold shifts of the compound action potential (CAP) from pre-ischemic values were compared with those of control animals 4 h after the onset of reperfusion. A statistically significant reduction in the post-ischemic CAP threshold shift was observed in the animals treated with deferoxamine or 3-bromo-7-nitroindazole. However, aminoguanidine did not affect the post-ischemic CAP threshold shift. These results suggest that free iron and nNOS play deleterious roles in the cochlear injury induced by transient ischemia.     

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。     

Immunocytochemical detection of peptides in the guinea pig cochlea

Summary The cochleae of juvenile guinea pigs were investigated for the presence of several neuropeptides. Glucagon, insulin, CCK and -endorphin immunoreactive neurons and nerve fibers as well as hair cells were demonstrated by the peroxidase antiperoxidase technique. Small amounts of substance P were also found in different sites in the inner ear. In contrast, prolactin-like material could not be found at all. These findings have significance with regard to the putative role of neuropeptides in neuromodulation.     

一氧化氮合酶抑制剂和神经营养因子3对噪声暴露下豚鼠耳蜗的保护作用

目的观察一氧化氮合酶抑制剂——N-硝基左旋精氨酸甲酯（N^G-nitro-L-arginine methyl ester，L-NAME）和神经营养因子3（neurotrophin 3，NT3）对噪声性听力损失的保护作用。方法80只雄性杂色豚鼠按区组随机分为非噪声组（n=20）和噪声暴露组（n=60），噪声暴露组又分为生理盐水组（n=20）、L-NAME组（n=20）、L-NAME＋NT3组（n=20）。L-NAME组和L-NAME＋NT3组动物在噪声暴露（4kHz倍频程、声压级115dB，5h）之前2d和噪声暴露前30min给予L-NAME 10mg／kg（腹腔注射），生理盐水组动物给予等体积的生理盐水。NT3（10μg／ml）在噪声暴露前4d经微量渗透泵（200μl，0．5μl／h）输入到L-NAME＋NT3组动物的右侧耳蜗鼓阶，持续到噪声暴露后10d。噪声暴露前和暴露后10d测试听性脑干反应（auditory brainstem response，ABR），暴露后3d测试耳蜗组织一氧化氮（nitric oxide，NO）水平，最后一次ABR测试后计数耳蜗毛细胞的存活率。结果无噪声暴露组动物无明显的听力改变和毛细胞缺失；生理盐水组动物的ABR阈移、毛细胞缺失率及耳蜗组织NO水平均高于L-NAME组和L-NAME＋NT3组，差异有统计学意义（P值均〈0．01）；与L-NAME组相比，L-NAME＋NT3组豚鼠的ABR阈移减小，差异有统计学意义（P〈0．01），而耳蜗组织NO水平和毛细胞缺失率差异则没有统计学意义（P=0．197及P=0．095）。结论与单独给予L-NAME相比，联合使用NT3可以更大程度减轻噪声对豚鼠耳蜗的损伤。