Objective To investigate effects of EGB761 on ABR threshold, hair cell nucleus staining and manga-nese superoxide dismutase (Mn-SOD) activity in the inner ear in rats with by impulse noise induced deafness. Methods SD rats (n=80) were randomly divided into a blank control (n=20) and an experiment (n=60) group. Rats in the experi-ment group received impulse noise exposure (150 dB SPL, pulse width=30 ms, repetition rate=1/min, total=3), and were then randomly selected to be examined immediate, or to receive intraperitoneal injection of EGB761 (Ginaton 4 ml/kg) or equivalent volume of saline, bid for 7 consecutive days before being examined. Results ABR thresholds in the ex-periment group were significantly elevated following impulse noise exposure (P<0.01), regardless of timing or treat-ment (P>0.05). After 7 days, ABRs thresholds improved in both saline and EGB761 treated animals, but more so in those treated with EGB761 than in those treated with saline (P=0.02). Immunofluorescence showed normal arrangement of outer hair cells nuclei in rats without noise exposure. Immediately following noise exposure, punctate deletion of out-er hair cell nuclei was noticed in the basal turn. On Day 7, significant lamellar deletion of outer hair cell nuclei was re-corded in rats treated with saline, more severe than immediately following exposure and than in those treated with EGB761 whose loss of outer hair cells nuclei was sparse and scattered. Mn-SOD results showed no statistically signifi-cant difference between noise exposed and non-exposed animals immediately following exposure (P>0.05);whereas on Day 7, inner ear Mn-SOD activity in rats treated with normal saline was significantly lower than immediately following exposure (P<0.01) and then in EGB761 treated rats (P=0.01). Conclusions EGB761 appears to mitigate auditory func-tion decline, hair cell loss and oxidative stress reaction, and improve the prognosis in pulse noise induced deafness.%目的 探究银杏叶提取物(Ginkgo biloba extract,EGB761)对脉冲所致噪声性聋的大鼠内耳ABR阈值、毛细胞核染色、及锰超氧化物歧化酶(Manganese superoxide dismutase,Mn-SOD)活性的影响.方法 80只SD大鼠随机分为2组:空白对照组20只、实验组60只.实验组大鼠均给予声压级为150dB脉冲噪声,脉宽为30ms,重复率为1/min,连续3发.脉冲噪声暴露后随机分成暴露即刻组、生理盐水组和EGB761组.EGB761组腹腔注射金纳多4ml/kg,2/日,连续注射7天;生理盐水组腹腔注射生理盐水4ml/kg,2/日,连续注射7天.结果 听觉脑干反应(Audi-tory Brain-Stem Response,ABR)结果显示噪声暴露后实验组大鼠ABR阈值显著高于暴露前,差异有统计学意义(P<0.01),各实验组大鼠间无统计学差异(P>0.05).治疗7天后,生理盐水组及EGB761组大鼠ABR阈值均下调,EGB761组大鼠ABR阈移明显高于生理盐水组,差异有统计学意义(P<0.05).免疫荧光结果显示空白对照组大鼠内耳底回外毛细胞细胞核排列整齐;噪声暴露即刻组大鼠内耳底回外毛细胞核排列稀疏,较正常对照组缺失明显增多,但仍以点状缺失为主;生理盐水组底回外毛细胞核缺失明显,且出现片状缺失,较暴露即刻组损伤严重;EGB761组较生理盐水组底回外毛细胞核排列稀疏散乱,但缺失明显减少,以点状缺失为主.Mn-SOD结果显示噪声暴露即刻组内耳Mn-SOD活性与空白对照组无统计学差异(P>0.05);生理盐水组Mn-SOD活性显著低于暴露即刻组,差异有统计学意义(P<0.01),EGB761组Mn-SOD活性明显高于生理盐水组,差异有统计学意义(P<0.05).结论 EGB761能明显改善脉冲所致噪声性聋的听功能下降、减少毛细胞消失及氧化应激反应,对脉冲所致噪声性聋的预后意义显著.
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