聚DL-天冬氨酸对庆大霉素耳毒性拮抗作用的实验研究

目的　研究聚ＤＬ天冬氨酸（ｐｏｌｙ ＤＬａｓｐａｒｔｉｃ ａｃｉｄ,ＰＡＡ） 对Ｆ３４４ 大鼠庆大霉素（ｇｅｎｔａｍｉｃｉｎ,ＧＭ） 耳毒性的拮抗作用。方法　选用健康Ｆ３４４ 大鼠５０ 只,随机分４ 组：Ⅰ为ＧＭ、Ⅱ为ＰＡＡ＋ ＧＭ、Ⅲ为ＰＡＡ、Ⅳ为生理盐水对照组;通过观测４ 组大鼠不同时期、不同频率听性脑干反应（ａｕｄｉｔｏｒｙ ｂｒａｉｎｓｔｅｍ ｒｅｓｐｏｎｓ,ＡＢＲ）阈值的改变;计数耳蜗毛细胞死亡率,以观察ＰＡＡ对Ｆ３４４ 大鼠ＧＭ 耳蜗毒性的拮抗作用;用双向扩散血清培养基检测法观察ＰＡＡ 对ＧＭ 抗菌活性的影响。结果　Ⅰ组短纯音１０ ｋＨｚ、８ ｋＨｚ ＡＢＲ阈值与其他３ 组差异有显著性（ Ｐ＜ ０．０１） ,给药１８ ｄ 耳蜗毛细胞死亡率与其他３ 组间差异也有显著性（ Ｐ＜０ ．０１）。结论　ＰＡＡ对庆大霉素的耳毒性具有拮抗作用,且不减低其抗菌活性。     

甲磺酸去铁胺抗庆大霉素耳毒性作用及机理研究

目的 探讨铁螯合剂甲磺酸去铁胺对抗庆大霉素耳毒性作用及其机理。方法 豚发为ＧＭ组（１７只）、ＤＦＯ组（８只）、ＧＭ＋ＤＦＯ组（１７只）及对照组（８只）,采用听性脑干反应,耳蜗铺片及透射电镜技术,观察用药前后听反应阈及形态学变化,检测血清尿素氮、革以及ＧＭ浓度,同时测定耳蜗和肾皮质组织中丙二醛、超氧化物歧化酶和铁离子含量。结果 ＧＭ组８ｋＨｚＡＢＲ阈移为４－６０ｄＢ;ＧＭ＋ＤＦＯ组阈移为１５－２５ｄ     

甲磺酸去铁胺抗庆大霉素耳毒性作用及机理研究

目的探讨铁螯合剂甲磺酸去铁胺（ｄｅｆｅｒｏｘａｍｉｎｅｍｅｓｙｌａｔｅ,ＤＦＯ）对抗庆大霉素（ｇｅｎｔａｍｉｃｉｎ,ＧＭ）耳毒性作用及其机理。方法豚鼠随机分为ＧＭ组（１７只）、ＤＦＯ组（８只）、ＧＭ＋ＤＦＯ组（１７只）及对照组（８只）,采用听性脑干反应（ａｃｏｕｓｔｉｃｂｒａｉｎｓｔｅｍｒｅｓｐｏｎｓｅ,ＡＢＲ）、耳蜗铺片及透射电镜技术,观察用药前后听反应阈及形态学变化,检测血清尿素氮、肌苷以及ＧＭ浓度,同时测定耳蜗和肾皮质组织中丙二醛、超氧化物歧化酶和铁离子含量。结果ＧＭ组８ｋＨｚＡＢＲ阈移为４０～６０ｄＢ;ＧＭ＋ＤＦＯ组阈移为１５～２５ｄＢ,差异有显著性（Ｐ＜０．０５）。形态学改变与听力变化一致。ＤＦＯ对ＧＭ血药浓度没有影响。ＧＭ组肾功明显损伤,但肾皮质丙二醛、超氧化物歧化酶和铁离子变化差异无显著性（Ｐ＞０．０５）,ＧＭ＋ＤＦＯ组耳蜗组织丙二醛和铁离子含量较ＧＭ组明显减少（Ｐ＜０．０５）,超氧化物歧化酶含量明显高于ＧＭ组（Ｐ＜０．０５）。结论自由基和铁离子在ＧＭ的耳毒性中起重要作用,ＤＦＯ能有效减轻ＧＭ的耳毒性作用,可能成为有希望的预防药物。     

甲磺酸去铁胺对抗庆大霉素耳毒性的实验研究

目的观察铁螯合剂———甲磺酸去铁胺（ｄｅｆｅｒｏｘａｍｉｎｅｍｅｓｙｌａｔｅ,ＤＦＯ）对抗庆大霉素（ｇｅｎｔａｍｉｃｉｎ,ＧＭ）耳毒性的作用。方法将豚鼠随机分为ＧＭ组、ＤＦＯ组、ＧＭ＋ＤＦＯ组及对照组,采用听性脑干反应（ＡＢＲ）、耳蜗铺片及透射电镜技术,观察用药前后听阈及形态学改变,并检测ＤＦＯ对庆大霉素血药浓度的影响。结果ＧＭ组８ｋＨｚＡＢＲ阈值逐渐升高４０～６０ｄＢ;ＧＭ＋ＤＦＯ组阈移为１５～２５ｄＢ,差异显著（Ｐ＜０．０５）。高频听阈损伤明显比低频更重（Ｐ＜０．０１）。形态学变化与听力变化平行。ＤＦＯ对庆大霉素血药浓度没有影响。结论证实ＤＦＯ能有效减轻ＧＭ的耳毒性作用,ＤＦＯ可能成为预防庆大霉素耳毒性的有效药物。     

自由基清除剂二甲基亚砜对庆大霉素耳蜗毒性的影响

观察豚鼠同时注射二甲基亚砜（ＤＭＳＯ）与庆大霉素（ＧＭ）及单独注射ＧＭ等几组动物后，耳蜗听功能、扫描电镜所见及耳蜗和血清中脂质过氧化物（ＬＰＯ）丙二醛（ＭＤＡ）含量的变化。结果表明ＧＭ＋ＤＭＳＯ组动物ＡＰ阈值较ＧＭ组明显降低，ＡＰ（Ｎ＿１）潜伏期ＧＭ组较ＧＭ＋ＤＭＳＯ组显著延长，耳蜗扫描电镜显示ＧＭ＋ＤＭＳＯ组毛细胞受损程度较ＧＭ组明显为轻。耳蜗中ＭＤＡ检测表明，ＧＭ组耳蜗中ＭＤＡ含量较ＧＭ＋ＤＭＳＯ组明显增高（Ｐ＜０．０１）。提示自由基引起耳蜗ＬＰＯ可能是ＧＭ耳毒性机制之一；ＤＭＳＯ可减轻ＧＭ的耳毒性。     

GDNF转基因表达对庆大霉素所致的耳蜗和前庭毒性的影响

神经胶质细胞源性神经营养因子（ｇｌｉａ ｃｅｌｌ ｌｉｎｅ－ｄｅｒｉｖｅｄ ｎｅｕｒｏｔｒｏｐｈｉｃ ｆａｃｔｏｒ ＧＤＮＦ）是转化生长因子－β超家族的一个远亲成员,在发育和成熟的耳蜗中均起潜在作用。为了解ＧＤＮＦ转基因表达对庆大霉素所致的耳蜗和前庭毒性的影响,该文作者将３２只豚鼠分为６组：（１）人工外淋巴组（４只）;（２）Ａｄ．ＬａｃＺ组（４只）;（３）庆大霉素组（４只）;（４）Ａｄ．ＬａｃＺ＋庆大霉素组（６只）;（５）Ａｄ．ＧＤＮＦ＋庆大霉素组（救援组,８只）;（６）应用庆大霉素后７天＋Ａｄ．Ｇ…     

内皮舒张因子对豚鼠耳蜗血管纹血管的保护作用

本实验利用活体显微镜摄像技术、透射电镜技术,观察了内皮舒张因子（ＥＤＲＦ）对豚鼠耳蜗微循环的保护作用。结果提示：（１）速尿组（Ｆ）动物,经静脉注射药１０ｍｉｎ后,耳蜗微动脉缺血,血管内皮细胞损伤;（２）地速尿／Ｌ－精氨酸组（Ｆ／Ｌ－Ａｒｇｉｎｉｎｅ）动物,ＥＤＲＦ能使速尿引起的微动脉缺血明显改善,血管纹血管超微结构的损伤程度较单纯Ｆ组减轻;（３）速尿／Ｌ－硝基－精且（Ｆ／Ｌ－ＮＮＡ）动物,耳蜗的缺     

成纤维细胞生长因子耳蜗内灌注防治爆震性聋的实验研究

选用豚鼠１９只，震前于圆窗龛放银球电极测复合动作电位（ＣＡＰ）反应阈，爆震后测ＣＡＰ，于耳蜗底回打孔，分别灌注酸性成纤维细胞生长因子（ａＦＧＦ）和碱性成纤维细胞生长因子（ｂＦＧＦ），４８小时后再测ＣＡＰ，处死动物做耳蜗琥珀酸脱氢酶（ＳＤＨ）组化染色铺片。结果爆震后灌注ｂＦＧＦ、ａＦＧＦ两组动物４８小时ＣＡＰ平均阈值分别为８８．７ｄＢ和９３．２ｄＢ，而单纯打孔组和灌注外淋巴组ＣＡＰ平均阈值分别为１１９．４ｄＢ和１０７．５ｄＢ，差异有显著性（Ｐ＜０．０５和０．０１）。铺片结果示灌流生长因子两组动物耳蜗毛细胞损伤程度比其他两组要轻。结果提示ｂＦＧＦ、ａＦＧＦ耳蜗内灌注对爆震性聋ＣＡＰ反应阈恢复有促进作用，在耳蜗声损伤过程中有保护和修复功用。     

内皮舒张因子对耳蜗微循环作用的实验研究

为探讨内皮依赖性舒张因子（ＥＤＲＦ）对耳蜗微循环的调节作用，本实验应用活体显微镜结合电视摄象的图像分析技术及血管纹螺旋韧带铺片技术，观察了不同剂量ＥＤＲＦ合成前体Ｌ－精氨酸（Ｌ－Ａｒｇ）及ＥＤＲＦ的合成制抑制Ｌ－硝基－精氨酸（Ｌ－ＮＮＡ）对耳蜗血清（ｃｏｃｈｌｅａｒｂｌｏｏｄｆｒｏｗ，ＣｏＢＦ）的作用，结果显示：Ｌ－Ａｒｇ１００ｍｇ／ｋｇ组药物在给药５分钟后蜗血管流速开始加快，２０分钟时平均增加达     

丹参对庆大霉素耳蜗毒性的防护作用

目的 探讨丹参对庆大霉素耳蜗毒性的防护作用。方法 择蒙古沙鼠３０只,随机分为３组：（１）庆大霉素组（ＧＭ组）;（２）庆大霉素＋丹参保护组（ＧＤ组）;（３）对照组（ＮＳ组）,每组１０只。ＧＭ组和ＧＤ组臂部肌肉注射庆大霉素１５０ｍｇ／ｋｇ／ｄ,ＧＤ组同时注射丹参１ｇ／ｋｇ／ｄ,对照组注射生理盐水１ｍｌ／ｄ,连续用药１４ｄ后观察耳蜗的形态和功能,结果 ＧＭ组耳蜗功能和结构损害严重,ＧＤ组耳蜗功能和结构损     

Experimental study on polyaspartic acid inhibition of gentamicin-induced generation of reactive oxygen species in guinea pig cochlea]

OBJECTIVE: To observe the polyaspartic acid(PAA) inhibition of gentamicin-induced reactive oxygen species generation in cochlea of guinea pig and to investigate the protective mechanism of polyaspartic acid on gentamicin ototoxicity. METHODS: Eighty-eight guinea pigs were divided randomly into four groups (GM, PAA + GM, PAA, and Saline). Gentamicin-induced reactive oxygen species (ROS) formation in cochlear tissue was detected directly with electron paramagnetic resonance (EPR) spectrometry at 1st, 5th and 10th day after administration of the drugs. At the same time, ABRs of guinea pigs were recorded and ultrastructural changes of lysosomes in the cochlear hair cells were observed with transmission electron microscopy. RESULTS: 1. At 1st day after administration of PAA and GM, there was some increase in EPR spectrometry in group GM and PAA + GM, There was no significant difference of ABR thresholds and ultrastructural changes of lysosomes in the cochlear hair cells among four groups(P > 0.05). 2. At 5th day, there was significant increase in of EPR spectrometry in group I (37.74 +/- 4.10, P < 0.01). At 10th day after administration of PAA and GM, there was no significant difference in EPR spectrometry among four groups (P > 0.05). In GM group, ultrastructural changes of lysosomes beneath cuticular plate of cochlear hair cells were more significant at 10th day than those at 5th day, including the increased number and volume of lysosome. In group GM, the longer the gentamicin administrated, the more significant increase in ABR thresholds had been noted. CONCLUSION: PAA significantly inhibits gentamicin-induced reactive oxygen species generation in cochlea of guinea pig, which showed that PAA has protective effect on gentamicin-ototoxicity and -phospholipidosis in guinea pigs.     

庆大霉素对豚鼠耳肾毒性的相关性实验研究

目的 探讨豚鼠庆大霉素耳性与肾毒性的关系。方法 通过ＡＢＲ测试,耳蜗铺片毛细胞片数,血液庆大霉素药代动力学分析,血ＢＵＮ、Ｃｒ值测定,肾标光镜下观察等方法,观察肌注庆大霉互后豚鼠的耳蜗功能及肾功能变化。结果 肌注庆大霉素二周组ＡＢＲ的ＩＶ波反应阈阈移明显高于肌注庆大霉素一周组及其生理盐水对照组。光镜下耳蜗铺片毛细胞计数二周组毛细胞缺失数明显多于一周组对于对照组。肌注纱二周组的血清庆大霉素清除率明显     

Circadian rhythm dependent kanamycin-induced hearing loss in rodents assessed by auditory brainstem responses.

An antimicrobial agent, kanamycin, has been shown to produce as an untoward effect, ototoxicity. The purpose of this study was to investigate differential effects of kanamycin ototoxicity as a function of Rx timing with regard to circadian rhythms. Four groups of comparable weight Sprague-Dawley rats received a daily subcutaneous dosage of 225 mg/kg kanamycin sulfate with each receiving the antibiotic at a different time: 8 AM (8A), 2 PM (2P), 8 PM (8P), and 2 AM (2A). The rats were housed in separate cages, in a room on a light-dark (12:12) illumination cycle with light between 6 AM and 6 PM. Hearing loss was assessed with the auditory brainstem response (ABR) using pure tone stimuli at 8, 16, 24, and 32 kHz. ABR measures were obtained before dosing began and 2, 4, and 6 weeks after the initial dosing. Kanamycin produced a hearing loss which reflected the total dosage given to each group. Significant differences in physiologic thresholds were observed for both timing of the daily dosage (p less than 0.05), and the 2, 4 and 6 week testings (p less than 0.001). After 2 weeks, the 8A group showed an average hearing loss of 11.5 dB at 32 kHz, with the other timed treatment groups exhibiting minimal effects (3.0-6.5 dB). For the 8A group at this frequency, the loss progressed at 4 (19.5 dB) and 6 (22.5 dB) weeks. The 2P group after 4 weeks exhibited similar losses as the 8A group for this frequency, with the loss at 6 weeks being even greater (34.0 dB). The 8P and 2A groups exhibited only slight losses over all frequencies.(ABSTRACT TRUNCATED AT 250 WORDS)     

应用畸变产物耳声发射观察褪黑素对庆大霉素耳毒性拮抗作用

目的 研究褪黑素（melatonin,MLT)对庆大霉素（gentamicin,GM)耳毒性的拮抗作用。方法 实验分为GM组，MTL＋GM组及生理盐水对照组，采用豚鼠畸变产物耳声发射（distortion product otoacoustic emission,DPOAE)，观察用药后DPOAE幅值及I／O曲线斜率的变化。结果 GM组用药3后，4，6，8kHz DPOAE幅值同对照组相比有显著性差异（P＜0．01）；I／O曲线斜率变小，在4，6，8kHz与对照组相比有显著性差异（P＜0．01）。GM＋MLT组用药后各频率段DPOAE幅值，与对照组相比地显著性差异；I／O曲线斜率无明显改变，同对照组相比无显著性差异（P＞0．05）。结论 MLT能有效拮抗庆大霉素的耳毒性作用。     

Investigation of the ototoxicity of gadoteridol (ProHance) and gadodiamide (Omniscan) in mice

Conclusion: In the mouse, when a tympanic perforation is present, gadoteridol does not seem to cause ototoxicity. Gadodiamide may cause mild ototoxicity other than toxicity to the outer hair cells of the cochlea.

Objectives: Endolymphatic hydrops have been visualized through intra-tympanic injection of gadolinium-based contrast agents (GBCAs) and three-dimensional fluid-attenuated inversion recovery (3-D FLAIR) magnetic resonance imaging. However, reports on the safety of GBCAs are limited. This study aimed to assess ototoxicity of gadoteridol and gadodiamide.

Method: In a prospective, randomized, controlled trial, myringotomies in the left ear were performed in 20 male C57 BL/6 mice. After testing the baseline auditory brainstem response (ABR) (range?=?8–32?kHz), the test solution (gadoteridol, gadodiamide, saline, or cisplatin) was injected into the left ear. ABR testing was repeated 14 days after test solution application. In morphological experiments, images of post-mortem surface preparations were assessed for cochlear hair cell status.

Results: At 14 days following gadoteridol application, there was no significant change in ABR thresholds at 8, 16, or 32?kHz. Gadodiamide application caused a significant change in the ABR threshold at 8?kHz. Apparent cochlear hair cell loss was not observed in the surface preparation after gadoteridol or gadodiamide application.     

Ginkgo biloba extract (EGb 761) protects against cisplatin-induced ototoxicity in rats.

HYPOTHESIS: A standardized Ginkgo biloba extract, EGb 761, may have protective effect against cisplatin-induced ototoxicity in rats. BACKGROUND: Cisplatin-induced ototoxicity is a major dose-limiting side effect in anticancer chemotherapy. Cisplatin-induced ototoxicity has been correlated to depletion of the cochlear antioxidant system and increased lipid peroxidation. EGb 761 contains potent antioxidants capable of scavenging free radicals, inhibiting nitric oxide synthesis, reducing lipid peroxidation, and protecting against apoptosis. The purpose of this study was to investigate the effect of EGb 761 on cisplatin-induced ototoxicity in rats. METHODS: Male Wistar rats were divided into four groups and were treated as follows: 1) vehicle control; 2) cisplatin (13 mg/kg, intraperitoneally) plus vehicle; 3) EGb 761 (200 mg/kg, intraperitoneally); and 4) EGb 761 plus cisplatin. Auditory brainstem responses (ABRs) were measured pretreatment and 72 hours posttreatment, and threshold shifts were analyzed. Endocochlear potentials (EPs) were also obtained at 72 hours posttreatment. Cochleae were harvested and processed for scanning electron microscopy after completion of auditory testing. RESULTS: Cisplatin-treated rats showed significant ABR threshold shifts across all frequencies (click, and 2-, 4-, 8-, 16-, and 32-kHz tones) compared with each of the other groups (p < 0.001). Rats treated with EGb 761 plus cisplatin did not show significant ABR threshold shifts (p > 0.05). Similarly, the EPs of cisplatin-treated rats were decreased significantly approximately 50% in comparison with the other groups (p < 0.001). The EPs of EGb 761 plus cisplatin-treated rats were decreased less than 20% compared with vehicle control group or the EGb 761 only group (p < 0.01). The scanning electron microscopy observation indicated severe outer hair cell loss in the basal turn of cochleae of cisplatin-treated rats, whereas outer hair cells remained intact in the rats treated with EGb 761 plus cisplatin. CONCLUSION: These results demonstrate that EGb 761 protects against cisplatin-induced ototoxicity.     

The protective effect of brain-derived neurotrophic factor after gentamicin ototoxicity.

HYPOTHESIS: Brain-derived neurotrophic factor (BDNF) influences the process of hair cell recovery in the vestibular sensory epithelium of the chinchilla after local application of gentamicin (GM). BACKGROUND: Hair cell regeneration in the inner ear after GM ototoxicity has been demonstrated. However, the mechanisms responsible for this recovery have yet to be completely elucidated. This report examines the protective and proliferative effects that BDNF exerts on vestibular hair cells in experiments designed to further elucidate the mechanisms of hair cell regeneration. METHODS: The inner ears of three separate groups of chinchillas were treated with GM only, GM and BDNF simultaneously, and GM followed by BDNF 1 week later. The numbers of hair and supporting cells in the horizontal cristae of each group were then estimated at 1, 2, 4, and 8 weeks, and the data were compared. RESULTS: Type I hair cells after GM treatment completely disappeared. After simultaneous BDNF and GM treatment, their numbers decreased to 23% at 1 week and progressively disappeared by week 8. When BDNF was applied 1 week after GM administration, type I hair cells recovered to 12% at week 4 and 28% at week 8. Type II hair cells after GM treatment decreased to 15%, but recovered to 83% 4 weeks later. Simultaneous administration of BDNF and GM prevented the ototoxic effects of GM alone. When BDNF was administered 1 week after GM, type II hair cell recovery was accelerated and was greater than after GM alone (81% versus 18%). Supporting cells after GM treatment decreased to 74% at 1 week after treatment, recovered to 91% at 2 weeks, and remained at 86% at 4 weeks and 85% at 8 weeks. With the simultaneous administration of BDNF and GM, supporting cells significantly decreased at 2 weeks after treatment (63%), but recovered to normal by week 8. CONCLUSIONS: These results suggest that BDNF provided simultaneously with GM minimizes the ototoxic effect of GM on type II hair cells. The increase in the number of new hair cells when BDNF is provided after ototoxic damage is evidence of the proliferative capacity of this neurotrophic factor.     

Chinchilla models of selective cochlear hair cell loss

Although it is well known that ethacrynic acid (EA) can enhance gentamicin (GM) ototoxicity, there has been no systematic study of the relationship between dosing parameters and inner ear pathology. We examined the effects of two parameters, GM dose and time delay between GM and EA administration, on cochlear and vestibular hair cell loss in chinchillas. 'No delay' groups received one injection of GM (125, 40, 20, or 10 mg/kg i.m.) followed immediately by EA (40 mg/kg i.v.); 'delay' groups received GM (10 mg/kg i.m.) followed by EA 1 or 1.5 h later. Animals were sacrificed 7 days later for evaluation of hair cell loss in the cochlea and vestibular end organs (cristae, saccule and utricle). Vestibular function was assessed prior to sacrifice by measuring the duration of nystagmus induced by cold caloric stimulation. No delay groups had approximately 100% loss of outer hair cells and dose-dependent losses of inner hair cells, ranging from approximately 100% to 58%. In 1 and 1.5 h delay groups, inner hair cell losses were approximately 19% and 0%, outer hair cell losses were approximately 74% and 47%, and outer hair cell loss followed a typical base to apex gradient. Two results were remarkable. First, the three groups with partial inner hair cell loss showed an atypical lesion pattern in which losses were substantially greater in the apical half than in the basal half of the cochlea. Second, there was no vestibular pathology in any group. The results establish dosing parameters that can be used to produce animal models with defined patterns and magnitudes of cochlear hair cell damage, but normal vestibular function and morphology.     

Ebselen attenuates cochlear damage caused by acoustic trauma

Ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one), a seleno-organic compound, mimics glutathione peroxidase and reacts with peroxynitrite. It is reported to protect against gentamicin- and cisplatin-induced ototoxicity. We investigated whether it protects the cochlea from acoustic trauma. Male pigmented guinea pigs (250-300 g) with normal auditory brainstem response (ABR) thresholds were exposed for 5 h to 125 dB sound pressure level octave band noise centered at 4 kHz. One hour before and 18 h after exposure, they received orally 0.25 ml chloroform solution containing 0, 10, or 30 mg/kg ebselen (n=6, 5 and 5, respectively). The protective effect of ebselen was evaluated by ABR measurement and quantitative hair cell assessment. Treatment significantly (P<0.01) reduced the extent of permanent threshold shifts and outer hair cell loss. Interestingly, the protective effect of a 30 mg/kg dose was less than that of a 10 mg/kg dose. There were no adverse systemic or auditory function effects in three unexposed control subjects given 30 mg/kg ebselen. These findings indicate that ebselen attenuates noise-induced cochlear damage. The concentration that provides optimal protection against such damage has now to be determined.