噪声暴露后豚鼠下丘可塑性和r-氨基丁酸（GABA）的改变

发布时间：2018-05-31 04:58

本文选题：下丘 + 豚鼠　；参考：《中国人民解放军军医进修学院》2010年博士论文

【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改变以及神经递质r-氨基丁酸(GABA)的改变,阐明噪声性耳鸣、听觉过敏、响度重振等症状发生的机理。研究分三部分：一、正常豚鼠下丘的电生理特性。研究发现：1.大部分频率地形图(FRA)为V-shape型(84.89%),其余为non-V-shape型。2.沿背腹轴方向,随着深度的增加,特征频率(CF)呈阶梯式增加。特征频率与其阈值(MT)的函数关系呈U形即低频和高频部分阈值较高。特征频率的阈值由浅到深总体表现为“V”型。3.反应率-强度函数(RIF)有五型：a)u1型,反应率-强度函数曲线缓慢上升到最大反应程度,最后呈下降趋势；b)u2型,反应率-强度函数曲线缓慢上升到最大反应程度。c)u3型,快速上升-平缓型,函数曲线快速上升,在30dB-40dB刺激强度时,反应率达到高峰,然后维持这一高度或缓慢上升直到最后。d)ud型,函数曲线快速上升,在30dB-40dB刺激强度时,反应率达到最高峰,然后快速下降,呈倒U形。e)N型,函数曲线形状呈N、M或W形。4.刺激后时间直方图(PSTH)有五型：A.抑制型,在纯音刺激过程中抑制自发放电。B.瞬态型,在纯音刺激最初25秒之内呈现兴奋反应,随后在整个刺激过程中跟着低放电。c.长潜伏期型,类似瞬态型,但有一个22ms的潜伏期,后面的波峰较宽。D.暂停／发放型,a.起初高的放电,紧接着短暂的下降,随后跟着中等程度的持续放电；b.长潜伏期接着一个平稳的放电。E.发放型,从一开始就出现较高的反应,有平稳的放电。二、噪声暴露后下丘的电生理改变：1.耳蜗损伤模型可靠。2.从震后1天开始,双峰型FRA和狭窄型FRA明显增多；震后11-21天,狭窄型FRA减少。3.CF与深度函数图中,在相当于4KHz的频率段有一个明显的断层,象正常组那样随着深度的增加cF呈阶梯式上升的规律被破坏,阶梯变平缓。4.cF平均持续深度比正常组明显增加。5.大多数频率段,震后组cF阈值较正常组均低。6.噪声暴露后1天内,特征频率阈上20dB带宽(BW20)没有增加,反而略降低；震后11天-21天,平均BW20比正常组明显增加。7.RIF的类型和正常组相同,但构成比例不同,随着震后时间延长,渐趋相同。8. PSTH的类型和正常组相同,但构成比例不同,随着震后时间延长,渐趋相同。三、噪声暴露后下丘的GABA改变：GABA神经元和GABAA、GABAB受体较正常组明显减少,随着时间延长,有所增加。结论：噪声性耳鸣、听觉过敏、言语分辨率下降的生理基础可能是下丘神经元调谐曲线变宽或变窄、发放类型改变、反应兴奋性增加,其物质基础之一是抑制递质GABA减少。
[Abstract]:Aim: to observe the changes of pure-tone stimulation coding mechanism of inferior colliculus neurons and the change of neurotransmitter r-aminobutyric acid (r-aminobutyric acid) after noise exposure to cochlear injury in guinea pigs, and to elucidate the mechanism of noise-induced tinnitus, auditory hypersensitivity and loudness. The study is divided into three parts: 1. Electrophysiological characteristics of inferior colliculus of normal guinea pigs. The study found that 1: 1. Most of the frequency topographic maps (FRAA) are of V-shape type 84.89, and the rest of them are non-V-shape type. 2. Along the direction of the dorsal abdomen axis, the characteristic frequency and CFS increased step by step with the increase of depth. The function relationship between the characteristic frequency and its threshold value (MTT) is U-shaped, that is, the low frequency and high frequency partial thresholds are higher. The threshold of characteristic frequency from shallow to deep is "V" type. 3. There are five types of reaction rate-strength function (RIF-1). The curve of rate-intensity function rises slowly to the maximum reaction level, and finally shows a downward trend. The curve of RIF-intensity function rises slowly to the maximum reaction degree, and the curve of responsibility-intensity function rises slowly to the maximum reaction degree. The function curve rises rapidly, and at the intensity of 30dB-40dB stimulation, the response rate reaches a peak, and then maintains this height or rises slowly until the last type. The function curve rises rapidly, at the intensity of 30dB-40dB stimulation. The reaction rate reached the highest peak and then decreased rapidly, with the shape of inverted U. Ebony N, and the shape of function curve NM or W. 4. The time histogram (PSTH) after stimulation has five types: A. Inhibition of spontaneous discharges during pure tone stimulation. Transient response was observed during the first 25 seconds of pure tone stimulation followed by low discharge. Long latency type, similar to transient type, but with a 22ms latency, the latter peak is wider. D. Suspension / distribution type. Initial high discharge followed by a brief decline followed by moderate sustained discharge b. A long incubation period followed by a steady discharge. Release type, from the beginning there is a higher response, there is a steady discharge. Second, the electrophysiological changes of inferior colliculus after noise exposure: 1. The model of cochlear injury is reliable. From one day after the earthquake, the bimodal FRA and narrow FRA increased obviously, the narrow type FRA decreased .3.CF and the depth function diagram in 11-21 days after the earthquake, there was an obvious fault in the frequency region corresponding to 4KHz. As in the normal group, with the increase of the depth, the law of step by step rise of CF was destroyed, and the average continuous depth of the ladder flattened. 4. The mean duration depth of CF increased significantly than that of the normal group. In most frequency regions, the cF threshold of the post-earthquake group is lower than that of the normal group. Within one day after noise exposure, the 20dB bandwidth on the threshold of characteristic frequency (BW20) did not increase, but decreased slightly, and the average BW20 increased significantly between 11 and 21 days after the earthquake compared with the normal group, the type of BW20 was the same as that of the normal group, but the proportion was different, and with the extension of the post-earthquake time, Tend to be the same. The type of PSTH is the same as that of normal group, but the proportion of PSTH is different, and with the extension of post-earthquake time, it gradually tends to be the same. 3. The changes of GABA in the inferior colliculus after noise exposure were significantly lower than those in the normal group. Conclusion: the physiological basis of noise-induced tinnitus, auditory hypersensitivity and decreased speech resolution may be the broadening or narrowing of the tuning curve of the inferior colliculus neurons, the change of the distribution type and the increase of the excitability of the response. One of its material bases is to inhibit the decrease of GABA.
【学位授予单位】：中国人民解放军军医进修学院
【学位级别】：博士
【学位授予年份】：2010
【分类号】：R764

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