醋酸铅对豚鼠耳蜗橄榄束传出神经毒性的研究

目的探讨醋酸铅对豚鼠内侧橄榄耳蜗传出神经的损害。方法 70只成年健康豚鼠随机分为对照组和实验组。对照组(10只)豚鼠腹腔注射生理盐水1ml,共7次。实验组又分为高铅组和低铅组(各30只),分别每天1次腹腔注射0.25%醋酸铅溶液40mg/kg和10mg/kg,连续一周,分别于停药后14、28天(各15只))进行血铅含量和畸变产物耳声发射(DPOAE)检测,检测完成后断头处死,行基底膜铺片染色。结果实验组醋酸铅染毒后,血清中铅含量迅速升高。对照组和低铅组耳蜗传出神经分布均匀,神经纤维连续,DPOAE出现了不同程度的对侧声抑制效应,低铅组14天和28天抑制幅度分别为3.06±1.19dB和2.86±1.33dB;高铅组14天后耳蜗传出神经纤维连续性中断,乙酰胆碱酯酶终末反应物减少,DPOAE对侧声抑制幅度下降为0.74±0.61dB;高铅组28天后传出神经损害最为显著,DPOAE未引出。结论铅可对豚鼠内侧橄榄耳蜗传出神经产生不可逆性的损害。

The Toxic Effect of Lead Acetate on Media Oilvocochlear Efferent Nerve in Guinea Pigs

Objective To investigate the toxic effect of lead acetate on media olivocochlear efferent nerve in guinea pig.Methods 70 healthy adult guinea pigs were randomly divided into 3 groups:10 guinea pigs as the control group,a group of 30 guinea pigs exposed to high dosage and low dosage in another group.For the control group,1 ml saline was injected into animal’s abdominal cavity,seven times in total.In the high dosage group,0.25% lead acetate solution was injected at 40 mg/kg,and in the low dosage group at 10 mg/kg both in the same way as that of in the control group.The content of lead acetate and distortion product otoacoustis emission was tested on the the 14th and 28th days after the last drug injection.The cochlear samples were obtained after sacrifice and underwent histochemical stain for acetylchlinesterase on the surface preparation.Results The blood lead content of exposure guinea pigs increased.After two weeks of enterocoelia injected lead acetate,the efferent nerves in the animals in the high dose lead group were impaired and showed some degree of cochlear contralateral suppression.Since four weeks after leading administration,the impairment of efferent nerves in high dose lead acetate with guinea pigs was aggravated progressively.The efferent nerve in low lead group was not impaired.Conclusion The lead slowly impairs the media olivochlear efferent nerve in a irreversible manner.