脑源性神经营养因子对耳蜗螺旋神经节的保护作用

目的　观察腺病毒携带的脑源性神经营养因子 (brainderivedneurotrophicfactor,BDNF)在豚鼠耳蜗中的表达 ,及噪声损伤后对螺旋神经节的保护作用。方法　 2 7只白色纯种豚鼠 ,暴露于135dBSPL ,4kHz的窄带噪声 4h。 7d后 ,12只经圆窗注入腺病毒携带BDNF(adenoviral mediatedBDNF ,ad BDNF) ,12只经圆窗注入ad LacZ ,3只注入人工外淋巴液。分别于 1、4、8周后取材 ,石蜡包埋中轴切片后 ,用免疫组化方法 (ABC法 )检测BDNF的表达。于光镜下计数螺旋神经节细胞。结果　在耳蜗各回中BDNF均有表达 ,4、8周组动物较 1周组动物表达弱。在 8周 ,注入ad BDNF组较ad LacZ组和人工外淋巴组螺旋神经节发生退行性病变的数目少 ,螺旋神经节细胞计数结果经统计学t检验 ,P <0 0 1,差异有显著性。结论　腺病毒携带的神经营养因子在耳蜗中能高效表达 ,在噪声损伤情况下腺病毒携带的脑源性神经营养因子对螺旋神经节有保护作用。该研究为基因治疗感音神经性聋提供了坚实的实验基础     

NT3重组腺病毒对耳蜗螺旋神经节的保护作用

目的　观察含有神经营养素 - 3(neurotrophin - 3,NT3)的重组腺病毒在豚鼠耳蜗中的表达及其在噪声损伤后对螺旋神经节的保护作用。方法　 2 7只白色纯种豚鼠 ,暴露于 135dBSPL、4kHz的窄带噪声中 4h。 7天后 ,12只经圆窗注入ad -NT3,12只经圆窗注入腺病毒携带的Lac2基因 (adenviruslacopron ,ad -LacZ) ,3只注入人工外淋巴液。分别于 1、4、8周后取材 ,石蜡包埋中轴切片后 ,用免疫组化方法 (ABC法 )检测NT3的表达。于光镜下计数螺旋神经节细胞。结果　在耳蜗各回中NT3均有表达 ,4、8周组动物较 1周组动物染色弱。注入ad -NT3组较ad -LacZ组和人工外淋巴组螺旋神经节发生退行性病变的数目少 ,螺旋神经节细胞计数结果经t检验有显著性差异 (P <0 .0 1)。结论　含有NT3的重组腺病毒在耳蜗中能高效表达 ,且在噪声损伤情况下对螺旋神经节有保护作用     

噪声诱导豚鼠耳蜗应激蛋白表达的研究

目的：探讨噪声对耳蜗应激蛋白（ＳＰ,亦即ＨＳＰ）的诱导。方法：用免疫组织化学结合图像分析技术检测噪声刺激后豚鼠耳蜗ＨＳＰ７０的表达。结果：在正常状态下耳蜗表达ＨＳＰ７０的部位（Ｃｏｒｔｉ器,螺旋神经节,血管纹,齿间细胞）经１００ｄＢ声强级的白噪声暴露４５ｍｉｎ后,其ＨＳＰ７０的表达均增强,其中以Ｃｏｒｔｉ器和螺旋神经节更明显,Ｐ值均小于０．０１。结论：白噪声对豚鼠耳蜗ＨＳＰ７０表达具有明显的诱导作用。     

Morphological changes in spiral ganglion cells after intracochlear application of brain-derived neurotrophic factor in deafened guinea pigs

When guinea pigs are deafened with ototoxic drugs spiral ganglion cells (SGCs) degenerate progressively. Application of neurotrophins can prevent this process. Morphological changes of rescued SGCs have not been quantitatively determined yet. It might be that SGCs treated with neurotrophins are more vulnerable than SGCs in cochleae of normal-hearing guinea pigs. Therefore, the mitochondria and myelinisation of type-I SGCs were studied and the perikaryal area, cell circularity and electron density were determined. Guinea pigs were deafened with a subcutaneous injection of kanamycin followed by intravenous infusion of furosemide. Brain-derived neurotrophic factor (BDNF) delivery was started two weeks after the deafening procedure and continued for four weeks. Four cohorts of cochleae were studied: (1) cochleae of normal-hearing guinea pigs; (2) of guinea pigs two weeks after deafening; (3) six weeks after deafening; (4) cochleae treated with BDNF after deafening. The deafening procedure resulted in a progressive loss of SGCs. Six weeks after deafening the size of mitochondria, perikaryal area and cell circularity of the remaining untreated SGCs were decreased and the number of layers of the myelin sheath was reduced. In the basal part of the cochlea BDNF treatment rescued SGCs from degeneration. SGCs treated with BDNF were larger than SGCs in normal-hearing guinea pigs, whereas circularity had normal values and electron density was unchanged. The number of layers in the myelin sheath of BDNF-treated SGCs was reduced as compared to the number of layers in the myelin sheath of SGCs in normal-hearing guinea pigs. The morphological changes of SGCs might be related to the rapid loss of SGCs that has been reported to occur after cessation of BDNF treatment.     

脑源性神经营养因子基因修饰的骨髓间充质干细胞在药物致聋豚鼠内耳的表达及保护作用

目的 探讨脑源性神经营养因子(brain-derived neurotrophic factor,BDNF)基因修饰的骨髓间充质干细胞(mesenchymal stem cell,MSC)在药物致聋豚鼠内耳的表达及对螺旋神经节细胞(spiral ganglion cell,SGC)的保护作用.方法 阿米卡星致聋的豚鼠随机数字表法分为两组,治疗组经鼓阶开窗注射BDNF基因修饰的MSC,对照组注射外淋巴液.各组分别在术后7 d及28 d处死动物,荧光定量反转录聚合酶链反应(RT-PCR)检测耳蜗组织中BDNF mRNA的表达,耳蜗切片计算SGC细胞密度,末端脱氧核苷酸转移酶介导dUTP缺口末端标记法(terminal deoxynucleotidyl transferase mediated dUTP nick end labeling,TUNEL)检测SGC凋亡情况.结果 治疗组在术后7 d和28 d的BDNF mRNA相对表达量均明显高于对照组,差异具有统计学意义(P值均＜0.01).治疗组术后7 d及28 d的SGC密度均高于对照组,并且治疗组术后7 d及28 d的SGC凋亡指数也比对照组明显下降,差异具有统计学意义(P值均＜0.01).结论 BDNF基因修饰的MSC在致聋豚鼠内耳中的表达时间超过28 d,对SGC具有保护作用.     

Expression and significance of endothelin 1 in spiral ganglion cells of guinea pig

OBJECTIVES: Endothelin 1 has many biological activities including actions in the nervous system. This study aimed to investigate the expression of the endothelin 1 in spiral ganglion cells of guinea pig and its significance in the auditory transmission. METHODS: Healthy guinea pigs were sacrificed and cardiac perfused with saline followed by 4% paraformaldehyde. Temporal bones were removed and fixed, decalcified in 10% EDTA, embedded in paraffin block and serially sectioned in 5 microm thick slice. Rabbit anti-endothelin 1 polyclonal antibody was used as primary antibody to examine the expression of endothelin 1 in the spiral ganglion by immunohistochemistry. RESULTS: Endothelin 1 expression was detected in spiral ganglion cells from the basal turn to the apical turn of the cochlea. CONCLUSIONS: The endothelin 1 presents in spiral ganglions cells of the guinea pig and might play a role in the auditory transmission.     

Exogenous BDNF rescues rat spiral ganglion neurons in vivo.

OBJECTIVE: To determine if exogenous neurotrophins can prevent spiral ganglion neuron degeneration in the rat cochlea. BACKGROUND: The loss of hair cells resulting in sensorineural hearing loss also leads to the secondary degeneration of spiral ganglion neurons. The effectiveness of cochlear implantation in patients with profound sensorineural hearing loss relies in part on the survival of spiral ganglion neurons; therefore, any therapy that can prevent or halt the loss of these neurons would be of potential clinical benefit. Previous research has shown that intracochlear infusion with neurotrophins can provide trophic support to SGNs in deafened guinea pigs. Whether this effect is seen in other species remains to be determined. METHODS: After documenting the rate of spiral ganglion neuron degeneration after ototoxic deafening, we investigated the trophic effects of exogenous brain-derived neurotrophic factor (BDNF) on rat spiral ganglion neurons. The left cochleae of profoundly deafened rats were implanted with a drug delivery system connected to a mini-osmotic pump. BDNF or artificial perilymph was infused for 28 days; then the cochleae were prepared for histological study. RESULTS: Treatment with BDNF led to a statistically significant increase in spiral ganglion neuron density and a highly significant increase in spiral ganglion neuron soma area compared with artificial perilymph-treated and untreated deafened cochleae. CONCLUSION: The study has demonstrated the trophic advantage of exogenous BDNF in the mature rat cochlea and provides confidence that spiral ganglion neuron rescue after sensorineural hearing loss with exogenous BDNF may have clinical application.     

脑活素拮抗豚鼠庆大霉素耳毒性机理的研究

目的探讨脑活素拮抗豚鼠庆大霉素耳毒性作用机理。方法取听力正常豚鼠60只,随机分为4组,每组15只A组(脑活素组),肌肉注射脑活素360mg·kg-1·d-1;B组(庆大霉素组),肌肉注射庆大霉素120mg·kg-1·d-1;C组(庆大霉素 脑活素组),肌肉注射庆大霉素 脑活素,剂量同上;D组(生理盐水组),肌肉注射等量生理盐水。各组均连续用药10d再饲养一周,第17d处死,取左侧听泡,进行琥珀酸脱氢酶化学组织染色观察其活性;取右侧听泡行石蜡包埋切片,在光镜下进行螺旋神经节细胞计数,免疫组织化学SP法检测脑源性神经生长因子(brain-derivedneurotrophicfactor,BDNF)在耳蜗中的表达。结果庆大霉素 脑活素组螺旋神经节细胞退行性病变数目明显低于庆大霉素组,神经纤维变性明显较少,琥珀酸脱氢酶活性明显增高,BDNF在耳蜗中呈阳性表达。结论脑活素对庆大霉素所致耳毒性有明显保护作用,其机理在于脑活素能拮抗庆大霉素对毛细胞有氧代谢的抑制,与BDNF对螺旋神经元的营养修复作用有关。     

A new method for drug application to the inner ear

Inner ear sensory cells are very susceptible to injuries and recovery after damage is very difficult. Recently several drugs including neurotrophic factors have been reported to protect against inner ear injury. The purpose of this experimental study is to find new methods for applying drugs to the inner ear that effectively protect against inner ear damage. Biodegradable hydrogel was used as a carrier for application of brain-derived neurotrophic factor (BDNF) into the inner ear of guinea pigs through the round window membrane. After application of BDNF the number of surviving spiral ganglion neurons increased following injury of inner ear hair cells and spiral ganglion neurons by ototoxic treatment. This result indicates that BDNF provides effective protection against inner ear damage and that biodegradable hydrogel is useful for application of drugs to the inner ear.     

噪声损伤和苯扎贝特干预对豚鼠耳蜗脂肪酸转运蛋白1和4表达的影响

目的观察豚鼠耳蜗脂肪酸转运蛋白1和4(fatty acid transport protein,FATP1,FATP 4)在噪声损伤和促脂肪酸代谢药物苯扎贝特干预前后的变化,探讨噪声性听力损失与FATP1、FATP4的关系。方法正常听力健康成年雄性Dunkin Hartley豚鼠21只随机分为对照组(15只)和干预组(6只),对照组在噪声暴露前随机选取3只(6耳)动物行耳蜗取材作为正常对照组,其余12只(24耳)与干预组(6只,12耳)一起予以白噪声(110 dB SPL,每天4小时,连续12天)暴露,干预组在噪声暴露的同时给予苯扎贝特(5 mg·kg-1·d-1)灌胃干预;在开始噪声暴露第6、12、24天行听性脑干反应(ABR)检测,采用脂肪酸特异性探针荧光标记技术检测脂类物质在豚鼠耳蜗的分布,采用免疫荧光染色技术、Western blot技术检测噪声暴露前后FATP1、PATP4在两组豚鼠耳蜗的表达变化。结果噪声暴露后对照组和干预组click声及4、8、16 kHz短纯音(tone burst)ABR(tb-ABR)反应阈较噪声暴露前显著升高,在噪声暴露的第12天,干预组4 kHz tb-ABR反应阈(16.25±5.82 dB SPL)明显低于对照组(32.27±5.92 dB SPL)(P<0.05);特异性脂肪酸探针荧光染色提示正常对照组豚鼠耳蜗脂类物质主要分布于基底膜外侧的Hensen细胞、螺旋神经节、血管纹,噪声暴露前免疫荧光染色显示FATP1主要表达于Corti器、螺旋唇,在螺旋神经节细胞、螺旋韧带、血管纹等少量表达;FATP4主要表达于耳蜗Corti器及螺旋韧带,在Corti器外侧的Hensen细胞、螺旋神经节、血管纹极少表达或不表达。噪声暴露后对照组(第12天)FATP1在Corti器、Hensen细胞、螺旋突、螺旋韧带的表达较噪声暴露前明显增加(P<0.01),对照组(第12天)和干预组(第24天)FATP4在Hensen细胞、螺旋唇、螺旋神经节的表达均较噪声暴露前明显增加(P<0.01),干预组(第24天)FATP4在血管纹的表达均较噪声暴露前增加(P<0.05),但对照组(第12天)FATP4在血管纹的表达均较噪声暴露前及干预组(第24天)明显降低(P<0.05);Western blot结果则提示对照组和干预组FATP1和FATP4在全耳蜗的表达均较噪声暴露前增加(P<0.05)。结论噪声损伤可提高FATP1和FATP4在豚鼠耳蜗部分组织的表达水平,促进耳蜗内脂肪酸转运;促脂肪酸代谢药物(苯扎贝特)干预可进一步改变FATP4在耳蜗的表达分布,从而在一定程度上防止噪声性听力损失或促进噪声性听力损失恢复;提示耳蜗内脂肪酸代谢水平可能是改善噪声性听力损失的重要因素。     

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     

用于毛细胞再生研究的噪声性聋动物模型的建立

目的观察高强度脉冲噪声暴露后豚鼠听功能及耳蜗结构的变化,探讨用于毛细胞再生研究的噪声性聋动物模型的建立方法。方法健康成年白色红目豚鼠50只,雌雄不限,体重250～300g。随机分成2组,正常对照组10只,噪声暴露组40只。给予脉冲噪声（压力峰值为175．0dB SPL,脉宽0．25ms,间隔时间20秒）连续暴露200次。于噪声暴露前及暴露后1周、4周、8周检测听性脑干反应（auditory brainstem respons,ABR）,毛细胞计数及耳蜗铺片免疫组化观察耳蜗结构变化。结果高强度脉冲噪声暴露后1周,40只豚鼠中有21只（52．5％）双耳各频率ABR阈值≥95dBSPL。继续观察至噪声暴露后4周及8剧,ABR阈值没有恢复,1周、4周、8周各频率ABR阈值比较无统计学差异（P〉0．05）。毛细胞计数结果显示,噪声暴露敛极重度聋后1周,内毛细胞平均缺失率为91．4％,外毛细胞平均缺失率为97．2％。免疫组化染色分析结果显示,噪声暴露致聋后1周,内、外毛细胞胞核大部分缺失,内毛细胞内侧及外毛细胞外侧的支持细胞的胞核存存。结论高强度脉冲噪声暴露可造成豚鼠极重度感音神经性聋,耳蜗毛细胞广泛缺失且无法内行恢复,而支持细胞夫部分仔留,是进行毛细胞再生研究的理想动物模型。     

稳态噪声性听神经损伤后耳蜗内人神经营养素-3基因重组腺病毒的表达与观察

目的观察含有人神经营养素-3(human neurotrophin-3,hNT-3)的重组腺病毒(Ad-NT3)在稳态噪声性听神经损伤后耳蜗内的表达。方法30只听力正常豚鼠暴露于稳态强噪声(130 dB SPL×5 h),3天后经鼓阶外淋巴腔内导入目的基因,24只注射Ad-NT3,6只注射人工外淋巴液作为对照。分别于基因导入后第11、28、56天取材,用免疫组织化学染色方法观察Ad-NT3在耳蜗内的转染。结果基因导入后第11天可见Ad-NT3在耳蜗内成功转染,耳蜗各回均有表达,表达强度在各回基本相等;第28天仍可见Ad-NT3在耳蜗内表达,蜗轴区表达最强,但较第11天表达减弱;56天时未见表达。结论NT-3重组腺病毒能在稳态噪声性听神经损伤后耳蜗内实现高效表达,表达可以持续相当长时间。     

The effect of Hath1 r-expression in of guinea pig cochlea at one month after noise damage

Objective To study effects of Adenovirus-mediated Hath1 expression in guinea pig cochlea at one month after exposure to intensive noise. Methods Normal hearing guinea pigs, weighing 250-300g, received exposure to 200 rounds of impulse noise at 170 dB sound pressure level (SPL). The virus vector was inoculated into the left cochlea 1 month after noise exposure. Animals were tested using ABR and prepared for morphological examinations includeing immunocytochemistry and SEM 4 weeks after vector inoculation. Results The adenovirus mediated report gene expressed in the damaged area. There were no significant differences between treated and control animal in ABR threshold and morphologic changes. No new hair cells appeared in the Hath1 reated animals. Conclusion Forced hath1 ver-expression in the cochlea 1 month after noise exposure does not lead to appearance of new hair cells.     

Cochlear implants and ex vivo BDNF gene therapy protect spiral ganglion neurons

Spiral ganglion neurons often degenerate in the deaf ear, compromising the function of cochlear implants. Cochlear implant function can be improved by good preservation of the spiral ganglion neurons, which are the target of electrical stimulation by the implant. Brain derived neurotrophic factor (BDNF) has previously been shown to enhance spiral ganglion survival in experimentally deafened ears. Providing enhanced levels of BDNF in human ears may be accomplished by one of several different methods. The goal of these experiments was to test a modified design of the cochlear implant electrode that includes a coating of fibroblast cells transduced by a viral vector with a BDNF gene insert. To accomplish this type of ex vivo gene transfer, we transduced guinea pig fibroblasts with an adenovirus with a BDNF gene cassette insert, and determined that these cells secreted BDNF. We then attached BDNF-secreting cells to the cochlear implant electrode via an agarose gel, and implanted the electrode in the scala tympani. We determined that the BDNF expressing electrodes were able to preserve significantly more spiral ganglion neurons in the basal turns of the cochlea after 48 days of implantation when compared to control electrodes. This protective effect decreased in the higher cochlear turns. The data demonstrate the feasibility of combining cochlear implant therapy with ex vivo gene transfer for enhancing spiral ganglion neuron survival.     

睫状神经营养因子防治强脉冲噪声对豚鼠内耳损伤的实验研究

目的探索应用睫状神经营养因子（ｃｉｌｉａｒｙｎｅｕｒｏｔｒｏｐｈｉｃｆａｃｔｏｒ,ＣＮＴＦ）防治强脉冲噪声对豚鼠内耳损伤的可能性,为强脉冲噪声致聋的防治提供新的方法。方法制作强脉冲噪声致聋豚鼠模型３６只,１８只应用ＣＮＴＦ肌内注射３周,１８只等量的生理盐水作对照,正常对照豚鼠１８只,进行耳蜗铺片计算机图像分析毛细胞计数,螺旋神经节细胞计数、耳蜗乙酰胆碱酯酶染色铺片观察和ＡＢＲ反应阈测定。结果正常对照组、噪声暴露后２１ｄ的生理盐水对照组和ＣＮＴＦ组耳蜗毛细胞平均总数（ｘ±ｓ,下同）分别为９０９４±１０３．６、７３５１±１９６．５、８５２２±２０３．１;而螺旋神经节细胞计数在耳蜗中轴切片第二回下段３组间差异有显著性,分别为５１±４．７２、２７±６．９４、３７±１０．４。乙酰胆碱酯酶染色铺片结果示ＣＮＴＦ组较生理盐水对照组耳蜗乙酰胆碱酯酶活性损失轻、范围小。结论ＣＮＴＦ在一定程度上能防止受损的螺旋神经节细胞及外毛细胞发生变性坏死,并可能促进其损伤的修复。     

Brain-Derived Neurotrophic Factor Modulates Auditory Function in the Hearing Cochlea

Neurotrophins prevent spiral ganglion neuron (SGN) degeneration in animal models of ototoxin-induced deafness and may be used in the future to improve the hearing of cochlear implant patients. It is increasingly common for patients with residual hearing to undergo cochlear implantation. However, the effect of neurotrophin treatment on acoustic hearing is not known. In this study, brain-derived neurotrophic factor (BDNF) was applied to the round window membrane of adult guinea pigs for 4 weeks using a cannula attached to a mini-osmotic pump. SGN survival was first assessed in ototoxically deafened guinea pigs to establish that the delivery method was effective. Increased survival of SGNs was observed in the basal and middle cochlear turns of deafened guinea pigs treated with BDNF, confirming that delivery to the cochlea was successful. The effects of BDNF treatment in animals with normal hearing were then assessed using distortion product otoacoustic emissions (DPOAEs), pure tone, and click-evoked auditory brainstem responses (ABRs). DPOAE assessment indicated a mild deficit of 5 dB SPL in treated and control groups at 1 and 4 weeks after cannula placement. In contrast, ABR evaluation showed that BDNF lowered thresholds at specific frequencies (8 and 16 kHz) after 1 and 4 weeks posttreatment when compared to the control cohort receiving Ringer’s solution. Longer treatment for 4 weeks not only widened the range of frequencies ameliorated from 2 to 32 kHz but also lowered the threshold by at least 28 dB SPL at frequencies ≥16 kHz. BDNF treatment for 4 weeks also increased the amplitude of the ABR response when compared to either the control cohort or prior to treatment. We show that BDNF applied to the round window reduces auditory thresholds and could potentially be used clinically to protect residual hearing following cochlear implantation.     

The effect of Hath1 over–expression in of guinea pig cochlea at one month after noise damage

ObjectiveTo study effects of Adenovirus–mediated Hath1 expression in guinea pig cochlea at one month after exposure to intensive noise.MethodsNormal hearing guinea pigs, weighing 250–300g, received exposure to 200 rounds of impulse noise at 170 dB sound pressure level (SPL). The virus vector was inoculated into the left cochlea 1 month after noise exposure. Animals were tested using ABR and prepared for morphological examinations includeing immunocytochemistry and SEM 4 weeks after vector inoculation.ResultsThe adenovirus mediated report gene expressed in the damaged area. There were no significant differences between treated and control animal in ABR threshold and morphologic changes. No new hair cells appeared in the Hath1 treated animals.ConclusionForced hath1 over–expression in the cochlea 1 month after noise exposure does not lead to appearance of new hair cells.     

The protective effects of ciliary neurotrophic factor on inner ear damage induced by intensive impulse noise]

OBJECTIVE: To evaluate the feasibility of using ciliary neurotrophic factor(CNTF) to treat intensive impulse noise-induced inner ear damage. METHODS: The guinea pigs were given either CNTF (CNTF group) or 0.9% sodium chloride (NS group) for 3 weeks after impulse noise exposure. The animals receiving neither medicine nor noise served as a control group. ABR threshold shifts, the cochlear AchE staining as well as the hair cell and spiral ganglion cell counting were carried out in three groups of animals. RESULTS: The numbers of damaged hair cells and spiral ganglion cells in the CNTF group was less than that in the NS group. AchE activity alteration was also less severe in the CNTF group. Similar to the morphological results, changes in the auditory function, represented by the ABR threshold shifts, was less in the CNTF group. CONCLUSION: CNTF can protect cochlear hair cells and spiral ganglion cells against intensive impulse noise exposure by decreasing degeneration and necrosis of the hair cells in some extent and expedite hearing recovery.     

Expression of heat shock protein 70 in immune response of the guinea pig inner ear]

OBJECTIVE: To explore whether the immune response of the inner ear could induce heat shock protein (hsp) 70 in guinea pig cochlea. METHODS: A model of autoimmune inner ear disease (AIED) was established by systemically immunizing the guinea pig with the homologous crude inner ear antigen (CIEAg). The immunized cochleae and normal control cochleae were examined for the expression of hsp70 with techniques of immunohistochemistry and in situ hybridization. RESULTS: In the control animals, the expression of the hsp70-like protein appeared only in the spiral ganglion, whereas in the cochleae with CIEAg immunization, strong expression of the hsp70-like protein and its mRNA appeared in the spiral ganglion as well as in the stria vascularis and the spiral ligament. The hearing thresholds were significantly increased in 10 out of 28 cochleae (35.7%) with CIEAg immunization. CONCLUSION: The results suggest that the immune response of the inner ear can induce the expression of hsp70 in the guinea pig cochlea.