同种异体内耳组织免疫后豚鼠听功能与内耳形态学变化的关系

目的 观察豚鼠接受环磷酰胺处理及免疫后其听功能与内耳形态学变化的关系。方法 采用86只白色红目豚鼠作为实验对象，其中32只动物提供粗制内耳抗原。实验组（42只）动物于腹腔注射环磷酰胺2d后用粗制内耳抗原接种，接种后4．6、8、10、12、14、20d时接受ABR检测及内耳形态光镜观察。对照组1（6只）不行任何处理，对照组2（6只）注射环磷酰胺，但不接种抗原。结果 接种后4d时67％动物ABR阈值明显提高，8d时为83％，14d时降为58％，20d时所有动物阈值恢复正常。光镜观察发现：接种后4d时，实验动物听功能受损耳出现炎性细胞浸润；8—12d时，所有实验动物内耳均有类似改变；6—14d时，内耳尚有血管周围炎、螺旋神经节细胞变性等改变，相关形态变化均以听功能受损耳明显为重；接种14d时，内耳炎性细胞浸润明显减轻，20d时，绝大多数动物内耳形态基本恢复正常。结论 豚鼠接受环磷酰胺预处理及同种异体内耳抗原接种后，其听功能与内耳形态学的变化基本相一致。     

腺病毒携带的LacZ基因在豚鼠耳蜗中的表达

目的 带有LacZ基因的腺病毒注入豚鼠耳蜗后,观察不同时间段LacZ基因的表达和分布情况及手术操作对听力的影响,为内耳基因治疗提供理论依据。方法 24只白色豚鼠术前及术后行听性脑干反应(ABR)检查。空白对照组经圆窗注入人工外淋巴液,实验组注入带有LacZ基因的腺病毒。分别于2天、l周、2周后取材。耳蜗标本经β-半乳糖苷酶(X-Gal)组织化学染色后做石蜡切片和耳蜗铺片。结果 腺病毒注入耳蜗后对听力影响不大。经X-Gal染色后整个耳蜗被染成蓝色。2天组表达产物最高,l周后逐渐降低。表达产物主要分布于柯蒂器的内外毛细胞、螺旋神经节细胞、基底膜下的间皮细胞。对照组均未着色。结论 通过圆窗注入腺病毒对听力没有影响,单一位点的接种就能使因子通过耳蜗液扩散到整个耳蜗。有效的基因转移在耳蜗是可行的,但表达相对短暂。     

Application of a corticosteroid (Triamcinolon) protects inner ear function after surgical intervention

HYPOTHESIS: Opening of the inner ear during stapes surgery or cochlear implantation may result in trauma to inner ear structures and possible hearing loss. The dual aim of the present study was to evaluate the effectiveness of locally applied Triamcinolon* to protect the inner ear against surgically induced trauma and to exclude possible ototoxic effects. METHODS: In an animal model (guinea pig), a corticosteroid (Triamcinolon) was topically applied to the inner ear, either by extracochlear application and diffusion through the round window membrane or by direct intracochlear application via a cochleostomy. Physiological effects of the steroid were investigated by monitoring the hearing of steroid treated animals in comparison to control animals treated with Ringer solution instead of Triamcinolon. Thresholds as well as input/output functions (I/O function) of compound action potentials (CAPs) in response to auditory stimuli were determined before the cochleostomy and at specific intervals up to 4 weeks after application of Triamcinolon. RESULTS: Extracochlear application of Triamcinolon induced only minor shifts of mean CAP thresholds but significantly increased mean maximal amplitudes of I/O function 14 d after application. No detrimental effects on cochlear function were noted; thus, indicating absence of ototoxicity for extracochlear application in the concentrations used. After the surgical trauma of cochleostomy, CAP thresholds increased by 12.5 dB directly after surgery and by 15.8 dB at day 3. Amplitudes of CAPs diminished. Intracochlear application of Triamcinolon resulted in significantly enhanced recovery of CAP thresholds and amplitudes of I/O function from initial loss over a period of 4 weeks. CONCLUSIONS: From these results, we conclude that extracochlear topical application of Triamcinolon has no ototoxic effect in the concentrations that were used and that intracochlear application supports an increased recovery of cochlear functions after surgical trauma. Furthermore, the results indicate a protective effect of corticosteroids, partially preventing progressive loss of hearing after cochleostomy over a period of 4 weeks. Intracochlear application of Triamcinolon may be useful to prevent hearing loss after surgical intervention on the inner ear; however, clinical safety and efficacy remain to be proven in clinical studies.     

Investigation of neural stem cell-derived donor contribution in the inner ear following blastocyst injection

BACKGROUND: Utilising the enormous proliferation and multi-lineage differentiation potentials of somatic stem cells represents a possible therapeutical strategy for diseases of non-regenerative tissues like the inner ear. In the current study, the possibility of murine neural stem cells to contribute to the developing inner ear following blastocyst injection was investigated. METHODS: Fetal brain-derived neural stem cells from the embryonic day 14 cortex of male mice were isolated and expanded for four weeks in neurobasal media supplemented with bFGF and EGF. Neural stem cells of male animals were harvested, injected into blastocysts and the blastocysts were transferred into pseudo-pregnant foster animals. Each blastocyst was injected with 5-15 microspheres growing from single cell suspension from neurospheres dissociated the day before. The resulting mice were investigated six months POST PARTUM for the presence of donor cells. Brainstem evoked response audiometry (BERA) was performed in six animals. To visualize donor cells Lac-Z staining was performed on sliced cochleas of two animals. In addition, the cochleas of four female animals were isolated and genomic DNA of the entire cochlea was analyzed for donor contribution by Y-chromosome-specific PCR. RESULTS: All animals had normal thresholds in brainstem evoked response audiometry. The male-specific PCR product indicating the presence of male donor cells were detected in the cochleas of three of the four female animals investigated. In two animals, male donor cells were detected unilateral, in one animal bilateral. CONCLUSION: The results suggest that descendants of neural stem cells are detectable in the inner ear after injection into blastocysts and possess the ability to integrate into the developing inner ear without obvious loss in hearing function.     

经完整圆窗膜途径EGFP基因在大鼠耳蜗中的表达

目的 研究经完整圆窗膜途径进行耳蜗基因转导的可行性及安全性，为内耳基因治疗提供实验基础和理论依据。方法 24只SD大鼠术前及术后分别行听性脑干反应(ABR)检查。实验组(18只)用阳离子脂质体携带的增强型绿色荧光蛋白(enhanced green fluoresent protein，EGFP)基因，对照组(6只)用生理盐水，注入置于圆窗龛处的明胶海绵内。分别于术后3、7、14天取双侧耳蜗标本做基底膜铺片观察。结果 于圆窗龛处放置明胶海绵的转导方法对听力无明显影响。转染耳蜗呈明显的绿色荧光。3天组表达产物最高，7天组逐渐降低，14天组更弱。对侧及对照组耳蜗均未见荧光表达。结论 于圆窗龛处放置明胶海绵进行基因转导的方法对听力没有影响，且能够成功转染耳蜗组织，是一种行之有效的方法。     

Augmented ototoxic effect of cisplatin in heterozygotes of the German waltzing guinea pig

It has previously been demonstrated that the carriers of the German waltzing guinea pig are less susceptible to noise trauma. To explore whether this represents a general resistance to inner ear trauma, carriers of the German waltzing guinea pig were exposed to the ototoxic agent cisplatin. Two doses of cisplatin were injected intravenously into anesthetized carriers and weight-matched control animals. Prior to and 96 h after the injections hearing thresholds were established by recording the auditory brainstem responses at 3.5, 7, 14, and 28 kHz. The cochleae were harvested to estimate hair cell loss and to analyze total platinum content. The carriers of the German waltzing guinea pig strain suffered from a more pronounced cisplatin-induced hearing loss compared to the control animals. The results suggest that mechanisms responsible for the protection against acoustic stress do not provide any protection against cisplatin in carriers of the German waltzing guinea pig.     

实验性自身免疫性内耳病耳蜗热休克蛋白70的表达

目的　探讨自身免疫性内耳病模型动物耳蜗热休克蛋白的表达。方法　利用同种异体内耳抗原免疫豚鼠 ,以建立自身免疫性内耳病 (autoimmuneinnereardisease ,AIED)动物模型 ,并应用免疫组织化学及原位杂位技术 ,研究热休克蛋白 (heatshockprotein ,hsp) 70在正常对照组及AIED模型动物实验组耳蜗中的表达情况。结果　对照组豚鼠螺旋神经节细胞中存在hsp70样蛋白基础表达 ;实验组 2 8耳中 10耳 (35 7% )听阈提高≥ 10dB ;此组动物螺旋神经节细胞和血管纹、螺旋韧带hsp70及其mRNA表达明显增强。结论　以粗制膜迷路抗原免疫豚鼠 ,听阈提高动物hsp70在螺旋神经节细胞和血管纹、螺旋韧带合成增加。     

自身免疫性内耳病的实验研究

用同种异体内耳抗原免疫豚鼠，观察听阈、血清免疫学、形态学及免疫病理学的改变，结果发现部分豚鼠ＡＰ（Ｎ＿１）反应阈明显升高、血清中出现抗内耳自身抗体，且表现有膜迷路积水、蜗轴血管炎、螺旋神经元细胞空泡变性、细胞数减少，特别是部分动物蜗轴血管和血管纹毛细血管内皮有ＩｇＧ沉积。提示通过这种实验方法可在部分动物成功地建立实验性自身免疫性内耳病动物模型。此外，就该模型与该病临床表现的相似性进行了比较。     

丹参酮滴耳液在豚鼠急性化脓性中耳炎中的作用研究

目的观察丹参酮滴耳液治疗豚鼠急性化脓性中耳炎中的药效学作用。方法18只豚鼠，左耳作为实验耳，右耳作为对照耳，应用金黄色葡萄球菌菌苗中耳腔注射法制备急性化脓性中耳炎模型，然后随机分为3组（6只/组），分别应用生理盐水、丹参酮滴耳液和氯霉素滴耳液中耳腔给药治疗，各0.2ml/次，2次/d，连续给药7d。实验结束时处死动物，取中耳黏膜，冰冻切片，光镜观察炎症细胞浸润情况并评分，同时行中耳腔分泌物细菌培养和菌落计数。造模前后及实验结束后均行ABR反应阈值记录。结果与生理盐水组比较，丹参酮滴耳液组炎症表现轻，炎症细胞浸润程度轻，菌落计数低，组间差异有统计学意义（P〈0.05），而且其ABR平均听阈明显低于另外两组（P〈0.05）。结论丹参酮滴耳液的抗菌效应可以应用于急性化脓性中耳炎的治疗，并发挥内耳保护作用。     

Relationship between three inner ear antigens with different molecular weights and autoimmune inner ear disease

Crude inner ear antigen (CIEAg) can induce autoimmune inner ear disease (AIED) although it is not known which subcomponent of CIEAg is involved. In this study, we investigated the relationship between 3 purified inner ear antigens (31, 42-45 and 60 kD proteins) and AIED, and determined their distribution in normal guinea pig cochlea. Three groups of guinea pigs were immunized with the three inner ear antigens and one group served as a control. The hearing thresholds, serum IgG level and morphological changes in the inner ear were observed. The expression of the three antigens in the cochlea was detected using immunohistochemical techniques. No obvious changes in hearing thresholds or inner ear morphology were observed between the control and 42-45 kD groups. Animals immunized with the 31 or 60 kD proteins showed a significant increase in hearing thresholds (p < 0.05 vs control), accompanied by morphological changes in the inner ear. The serum IgG level was increased significantly (p < 0.05) in all immunized animals. The 31 kD protein was distributed in the cochlear nerve and spiral ganglion, while the 42-45 and 60 kD proteins were distributed widely, being found in the spiral ganglion, organ of Corti, stria vascularis and spiral ligament. These results suggest that two subcomponents of CIEAg (the 31 and 60 kD proteins) may induce AIED independently, that several inner ear antigens may contribute to the pathogenesis of AIED and that the 31 kD protein is of high tissue specificity and may be used as a marker protein for the clinical diagnosis of AIED.     

Effects of intraoperatively applied glucocorticoid hydrogels on residual hearing and foreign body reaction in a guinea pig model of cochlear implantation

Conclusion: The intraoperative application of glucocorticoid-loaded hydrogels seems to cause a reduction in neutrophil infiltration. No beneficial effect on hearing thresholds was detected. Objectives: To evaluate the application of dexamethasone- and triamcinolone acetonide-loaded hydrogels for effects on hearing preservation and foreign body reaction in a guinea pig model for cochlear implantation (CI). Methods: A total of 48 guinea pigs (n = 12 per group) were implanted with a single channel electrode and intraoperatively treated with 50 μl of a 20% w/v poloxamer 407 hydrogel loaded with 6% dexamethasone or 30% triamcinolone acetonide, a control hydrogel, or physiological saline. Click- and tone burst-evoked compound action potential thresholds were determined preoperatively and directly postoperatively as well as on days 3, 7, 14, 21, and 28. At the end of the experiment, temporal bones were prepared for histological evaluation by a grinding/polishing technique with the electrode in situ. Three ears per treatment group were serially sectioned and evaluated for histological alterations. Results: The intratympanic application of glucocorticoid-loaded hydrogels did not improve the preservation of residual hearing in this cochlear implant model. The foreign body reaction to the electrode appeared reduced in the glucocorticoid-treated animals. No correlation was found between the histologically described trauma to the inner ear and the resulting hearing threshold shifts.     

Cell proliferation in endolymphatic sac during the immune response of inner ear]

OBJECTIVE: To study the cell proliferation in endolymphatic sac(ES) during the secondary immune response in inner ear. METHODS: Fifteen healthy, female SD rats were employed in the experiment. Sensitized systematically with keyhole limpet hemocyanin (KLH), the animals were inoculated with the same antigen through cochlea basal turn into the labyrinth. Administrated 5-bromo-2'-deoxyuridine (BrdUrd) intraperitoneally, the rats were sacrificed and the temporal bones were harvested at 3, 7, 14 day after labyrinth vaccination respectively. The frozen sections of the decalcified samples were dealt with H-E staining and immunohistochemical methods to investigate the cellular infiltration, BrdUrd and IgG positive cells in the ES. RESULTS: While the ES lumen and perisaccular region were infiltrated with mononuclear-phagocyte at the 3rd day post-vaccination, plasmocyte and lymphatic cells become the predominant infiltrating cells in the ES at the 7th day. The KLH in the ES lumen were phagocytized at the 3-7th day post-vaccination. S-phase cells and IgG positive cells in ES increased markedly in the 3rd day and 7-14 days post-vaccination respectively with similar localization. CONCLUSION: The activity of cell proliferation in the ES enhance and local proliferated cells may differentiate in situ into immunocompetent cells during the secondary immune response against TD antigen in the inner ear. This indicates that ES plays an important role in immune response of inner ear.     

adenoviral-mediated hath1-egfp gene transfer into guinea pig cochlea through intact round window membrane

Objective To study expression of adenovira1-mediated Hathl-EGFP gene in the guinea pig cochlea after transfer through intact round window membrane (RWM), and to assess its effects on hearing. Methods Twenty adult guinea pigs were used, of which: 12 were surgically inoculated with AdHath1-EGFP in the bony groove of round window niche, and 8 with artificial perilymph. Auditory brainstem response(ABR) thresholds were determined in all animals before and 5 days after surgery. On post-surgery day 5 and day 14, animals were sacrificed and whole mounts of cochlea and fro zensections were examined. Results ABR tests showed no significant change of hearing after the surgery.Strong fluorescence staining in the cochleae was seen in Ad-Hathl-EGFP groups. The highest levels of gene expression were seen in the post-surgery day 5 group with tittle decrease on post-surgery day 14.The contralateral cochlea and those in the control groups were free of fluorescence staining. Conclusion The transgenic Hath1-EGFP can be effectively delivered into the inner ear through intact RWM, in an atraumatic manner.     

Histologic changes after semicircular canal occlusion in guinea pigs.

HYPOTHESIS: Histologic changes occurring after varying degrees of surgical trauma to the inner ear in guinea pigs can reveal the mechanism of hearing preservation/loss. BACKGROUND: Surgical approaches to the inner ear that allow for hearing preservation have gained increasing acceptance in neurotologic surgery. The mechanisms responsible for hearing preservation and hearing loss after partial labyrinthectomy are as yet poorly understood. METHODS: Ten animals underwent semicircular canal occlusion, suctioning of perilymph, ampullectomy, or wide vestibulotomy. Tone-burst auditory brain stem response (ABR) thresholds were performed at weekly intervals after surgery. After 4 weeks, temporal bone specimens were processed to obtain 10-jim sections from plastic-embedded ears. The histologic findings were correlated with the initial and final ABR thresholds. RESULTS: After surgical occlusion of one or more semicircular canals, ABR thresholds were preserved, as the authors reported previously. Suctioning of inner ear fluid led to transient loss of thresholds with recovery. Ampullectomy produced dichotomous results, with some subjects preserving auditory function and others losing auditory function. Wide vestibulotomy resulted in permanent loss of auditory function in most cases. Histologically, there was intraluminal fibrosis and inflammation near the site of surgical entry. Most specimens showed normal cochlear architecture and hair cell counts, irrespective of the degree of hearing loss. Vestibular hair cells were also well preserved, even when they were close to the site of surgical injury. CONCLUSIONS: These findings suggest that electromechanical changes, rather than cell death, are responsible for changes in auditory and vestibular function after partial labyrinthectomy.     

同种异体内耳组织免疫后豚鼠内耳形态学变化

目的建立一高阳性率、可供圆窗给药治疗内耳病研究用的自身免疫性内耳病动物模型。方法实验动物为86只豚鼠,其中32只用于制备粗制内耳抗原。其余动物随机分为实验组42只,对照组1、2各6只。将实验组动物腹腔注射环磷酰胺进行预处理,2d后用粗制内耳抗原行皮下多点接种,分别于接种后4、6、8、10、12、14、20d时用光镜观察动物内耳形态学变化,并检测其血清中IgG、IgM、C3、CH50、循环免疫复合物(CIC)水平。对照组1不行任何处理,对照组2不接种内耳抗原,余同试验组。结果接种后豚鼠耳蜗、前庭、内淋巴囊等部位出现以淋巴细胞为主的炎性细胞浸润,尤以前庭阶、鼓阶、螺旋神经节区域及耳蜗底圈等部位为重。接种后4d时,67%动物内耳有炎性细胞浸润;8~12d时,100%动物出现炎性细胞浸润;接种14d后,炎性细胞浸润明显减少。接种6~14d时,内耳尚有血管周围炎、螺旋神经节细胞变性、内淋巴积水等改变。结论将豚鼠采用环磷酰胺预处理及同种异体内耳抗原接种,可建立一高阳性率的自身免疫性内耳病动物模型。     

Effects of aging on normal hearing loss and noise-induced threshold shift in albino and pigmented guinea pigs

In a previous investigation into noise-induced hearing loss by comparing 2-month-old albino with pigmented guinea pigs, albinos displayed significantly greater shifts in cochlear microphonic (CM) threshold and less recovery than the pigmented animals 7 days after noise exposure. The present study compared the responses of 14-month-old albino and pigmented guinea pigs to the same noise parameters used previously. Thresholds for the first detectable elicitation of CM for three pure tones were recorded prior to, at 90 min and at 7 days after a 45-min exposure to 126 dB broadband noise. Before exposure to noise, thresholds for pigmented guinea pigs were 24 dB higher than those in the albinos. Following noise exposure, the pigmented animals showed less than half the amount of threshold shift displayed by the albinos. This change ws attributed to the higher pre-exposure thresholds in the pigmented guinea pigs. Converging lines of evidence suggest that cochlear pigmentation may have both protective and toxic influences on the inner ear.     

Inner ear autoantibodies in patients with rapidly progressive sensorineural hearing loss

Recognition of immune-mediated sensorineural deafness that responds to immunosuppressive therapy has led to a search for a diagnostic assay to identify inner ear autoantibodies. Without a confirmed diagnosis of autoimmune disease, many patients have undergone inappropriate immunosuppressive treatment or developed irreversible inner ear damage. Serum from patients with progressive sensorineural hearing loss (n = 54), ulcerative colitis (N = 5), normal controls (N = 14), and animals with experimental autoimmune sensorineural hearing loss (EASNHL) were analyzed by Western blot against fresh bovine inner ear antigen preparations. The hearing loss group (19 [35%]) showed a single-or double-band migrating at 68,000 molecular weight (MW), differing from the normal group (1 of 14 [7%]) which showed a similar band (P = .031). Upon analysis by two-dimensional gel electrophoresis both the EASNHL guinea pigs and a patient reacted against identical components of inner ear antigen. These results suggest an autoimmune basis for disease in patients reacting against the 68,000 MW antigen.     

Auditory outcomes following implantation and electrical stimulation of the semicircular canals

We measured auditory brainstem responses (ABRs) in eight Rhesus monkeys after implantation of electrodes in the semicircular canals of one ear, using a multi-channel vestibular prosthesis based on cochlear implant technology. In five animals, click-evoked ABR thresholds in the implanted ear were within 10 dB of thresholds in the non-implanted control ear. Threshold differences in the remaining three animals varied from 18 to 69 dB, indicating mild to severe hearing losses. Click- and tone-evoked ABRs measured in a subset of animals before and after implantation revealed a comparable pattern of threshold changes. Thresholds obtained five months or more after implantation--a period in which the prosthesis regularly delivered electrical stimulation to achieve functional activation of the vestibular system--improved in three animals with no or mild initial hearing loss and increased in a fourth with a moderate hearing loss. These results suggest that, although there is a risk of hearing loss with unilateral vestibular implantation to treat balance disorders, the surgery can be performed in a manner that preserves hearing over an extended period of functional stimulation.     

Mitigation of hearing loss from semi-circular canal transection in pseudomonas otitis media with ciprofloxacin-dexamethasone irrigation.

HYPOTHESIS: Irrigation of the mastoid with a quinolone antibiotic-steroid solution may mitigate hearing loss caused by iatrogenic semicircular canal injury in the presence of Pseudomonas aeruginosa (PA) otitis media (OM). BACKGROUND: Studies have shown the cochlea to be more vulnerable to semicircular canal transection (SCT)-related hearing loss in the presence of PA OM. Prophylactic systemic antibiotics and steroids may decrease this hearing loss, but SCT is usually not planned. The aim of this study was to determine if irrigation with ciprofloxacin-dexamethasone (cipro-dex) could improve hearing outcomes following SCT in PA OM. METHODS: PA OM was induced in 28 animals. After three to five days, unilateral SCT was performed in each animal, with sham SCT on the contralateral ear. At surgery, half of the animals (n = 14) underwent irrigation of the both mastoid bullae with cipro-dex; the second group of animals (n = 14) underwent irrigation of the bullae with sterile saline. Auditory thresholds were obtained immediately prior to SCT and 7-10 days after SCT. RESULTS: SCT ears treated with cipro-dex showed a mean click threshold improvement of 4.6 dB from pre-transection to 7-10 days post-transection, whereas thresholds in the SCT ears treated with saline worsened by 7.5 dB (p = 0.15). CONCLUSION: Irrigation of the guinea pig bulla with cipro-dex following SCT in the setting of PA OM appears safe and may yield beneficial effects on hearing.     

Folic acid improves inner ear vascularization in hyperhomocysteinemic mice

More than 29 million adults in the United States have been diagnosed with hearing loss. Interestingly, elevated homocysteine (Hcy) levels, known as hyperhomocysteinemia (HHcy), are also associated with impaired hearing. However, the associated mechanism remains obscure. The collagen receptor such as discoidin domain receptor 1 and matrix metalloproteinase (MMP) play a significant role in inner ear structure and function. We hypothesize that HHcy increases hearing thresholds by compromise in inner ear vasculature resulted from impaired Hcy metabolism, increased oxidative stress, collagen IVa and collagen Ia turnover. The treatment with folic acid (FA) protects elevated hearing thresholds and prevents reduction in vessel density by lowering abundant collagen deposition and oxidative stress in inner ear. To test this hypothesis we employed 8 weeks old male wild type (WT), cystathionine-beta-synthase heterozygote knockout (CBS+/-) mice, WT + FA (0.0057 μg/g/day, equivalent to a 400 μg/70 kg/day human dose in drinking water); and CBS(+/-) +FA. The mice were treated for four weeks. The hearing thresholds were determined by recording the auditory brainstem responses. Integrity of vessels was analyzed by perfusion of horseradish peroxidase (HRP) tracer. Endothelial permeability was assessed, which indicated restoration of HRP leakage by FA treatment. A total Hcy level was increased in stria vascularis (SV) and spiral ligament (SL) of CBS+/- mice which was lowered by FA. Interestingly, FA treatment lowered Col IVa Immunostaining by affecting its turnover. The levels of MMP-2, -9, methylenetetrahydrofolate reductase (MTHFR) and cystathione gamma lyase (CSE) were measured by Western blot analysis. The oxidative stress was high in SV and SL of CBS+/- compared to WT however the treatment with FA lowered oxidative stress in CBS+/- mice. These data suggested that hearing loss in CBS+/- mice was primarily due to leakage in inner ear circulation, also partly by induced collagen imbalance, increase in Hcy and oxidative stress in inner ear.