[噪声暴露后豚鼠下丘γ-氨基丁酸及电生理变化]

[Changes of gamma-amino butyric acid and electrophysiology inferior colliculus after noise exposure in guinea pig].

作者信息

Wang Feng, Hong Bo, Han Dong-yi, Zhao Ling-yun, Sui Ya-nan, Liu Yu-qian, Guo Wei, Liu Hui-zhan, Liu Liang-fa

机构信息

Department of Otolaryngology, First Affiliated Hospital, Chinese PLA General Hospital, Beijing 100048, China.

出版信息

Zhonghua Yi Xue Za Zhi. 2012 Jun 12;92(22):1565-8.

PMID:22944065

Abstract

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 GABA(A) and GABA(B) 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) GABA(A)/GABA(B) 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.

摘要

目的

探讨噪声暴露致豚鼠耳蜗损伤后下丘（IC）神经元的变化，以阐明纯音编码机制，观察声创伤致耳蜗损伤后IC中γ-氨基丁酸（GABA）的变化，了解噪声性耳鸣、听觉过敏及响度重振等症状的可能机制。

方法

观察噪声暴露致耳蜗损伤后第1天及11 - 21天豚鼠IC神经元对纯音刺激的反应，并以正常豚鼠的IC神经元作为对照。采用逆转录聚合酶链反应（RT-PCR）检测GABA(A)和GABA(B)受体的浓度。

结果

（1）实验组频率反应区（FRA）类型与对照组相同（V形84.8%，W形8.9%，N形6.3%）。但噪声暴露后第1天（V形63.9%，W形18.1%，N形18.1%）和第11 - 21天（V形84.2%，W形12.3%，N形3.5%）各类型百分比有明显差异。（2）噪声暴露后，对应4 kHz（噪声频率）的特征频率（CF）和深度功能图存在明显异常。实验组CF与深度线性功能图的斜率低于对照组。对照组、噪声暴露后第1天及11 - 21天的斜率分别为6.6、5.8、5.2。（3）与正常对照组相比，暴露后第1天、11天和21天GABA(A)/GABA(B)受体明显降低。且随着暴露后时间延长，其值逐渐升高。上述结果与IC的电生理变化相符。