中文摘要：

目的观察噪声暴露耳蜗损伤后豚鼠下丘神经元对纯音刺激编码机制的电生理改变以及神经递质γ-氨基丁酸（GABA）的改变，为探索噪声性耳鸣、听觉过敏、响度重振等症状发生的可能机制提供实验依据。方法观察噪声暴露后1d组和11-21d组豚鼠下丘神经元对纯音刺激的反应，以正常豚鼠下丘神经元为对照组。以反转录（RT）-PCR方法检测下丘神经元GABA受体的表达。结果（1）实验组频率反应面积图类型与对照组（V-shoe型84．8％，W-shoe型8．9％，N．shape型，6．3％）相同，但其类型构成百分比在噪声暴露后1d组（V-shape型63．9％，W-shoe型18．1％，N-shoe型18．1％）和11-21d组（V-shoe型84．2％，W-shape型12．3％，N-shoe型3．5％）明显不同。（2）实验组特征频率（CF）与深度函数图在相当于4kHz的频率段有一个明显的断层。CF随着深度的增加而升高的线性函数斜率变小。对照组、噪声暴露后1d组、噪声暴露后11-21d组中，CF与深度线性函数的斜率分别为：6．6、5．8、5．2。（3）噪声暴露后1、11、21d组中，GABA。和GABA。受体的含量明显减少，随着噪声暴露后天数的增加，GABA。受体和GABA。受体的含量逐渐增加。下丘神经元GABA受体含量随着噪声暴露后时间的延长而变化的规律与其电生理变化的规律相一致。结论噪声暴露耳蜗损伤后，豚鼠下丘神经元对纯音刺激编码机制发生改变，并随着噪声暴露后时间的延长发生变化，下丘神经元GABA受体是这些电生理改变的物质基础之一。

英文摘要：

Objective To explore the changes of inferior collicular （IC） neurons after noise exposure cochlea injury in guinea pig to elucidate the encoding mechanism of pure tones, observe the changes of IC gamma-amino butyric acid （GABA） after cochlear damage by acoustic trauma and understand the possible mechanism of symptoms such as noise-induced tinnitus, hyperacusis and loudness recruitment. Methods The responses of IC neurons to pure tone stimuli were observed in guinea pig at Day 1 and Days 11 -21 after cochlear damage induced by noise exposure. And the IC neurons of normal guinea pig were assigned as the controls. Reverse transcription-polymerase chain reaction （RT-PCR） was used to measure the concentrations of GABAA and GABAs receptors. Results （ 1 ） The types of frequency reaction area （FRA） in the experiment group were the same as those in the control group （ V-shape 84.8%, W-shape 8.9% , N-shape 6.3% ）. But the percentages of types were markedly different at Day 1 （ V-shape 63.9% , W-shape 18.1% , N-shape, 18. 1% ） and Days 11 - 21 （ V-shape 84.2%, W-shape 12.3% , N-shape 3.5% ） after noise exposure. （2） After noise exposure, there was a marked fault in characteristic frequency （CF） and depth function map corresponding to 4 kHz（ noise frequency）. The rake ratio of CF and depth linear function map in the experiment group was lower than that of the control group. The control group, Day 1 and Days 11 -21 after noise exposure, the rake ratios were 6.6, 5.8, 5.2 respectively. （3） GABAA/GABAB receptors decreased markedly at Days 1, 11 and 21 post-exposure compared to normal controls. And the values increased gradually with the prolonged time after exposure. The above findings conformed to the changes of electrophysiology of IC. Conclusions After acoustic trauma, the responses of IC neurons to pure tone stimuli change with the elongation of time. It may be explained by the changes of IC GABA receptors after noise exposure.