Detection of glutamate decarboxylase isoforms in rat inferior colliculus following acoustic exposure
Detection of glutamate decarboxylase isoforms in rat inferior colliculus following acoustic exposure
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DOI：
10.1016/s0306-4522(99)00300-0
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发表时间：
1999-01-01
期刊：
影响因子：
3.3
通讯作者：
Caspary, DM
中科院分区：
文献类型：
--
作者：
Abbott, SD;Hughes, LF;Caspary, DM
下丘是听觉中枢结构，是上行和下行听觉信息整合的场所。听觉中枢结构的变化可能与声暴露有关，这不能仅用耳蜗功能的改变来解释。将大鼠暴露于100 dB SPL的10 kHz音调中9 h。听觉脑干反应测量显示，在所有测试频率的初始25-30 dB的阈值偏移。到暴露后30天，点击和大多数频率的阈值恢复到接近对照水平;然而，阈值在10和20 kHz时仍然升高。内毛细胞损失仅限于耳蜗的顶端和基底端，并且不超过20%。下丘水平的两种异构体的GABA合成酶谷氨酸脱羧酶（65,000和67,000摩尔。WT形式）在暴露后立即（0小时）和暴露后2天和30天使用定量免疫细胞化学和蛋白质印迹技术测量。零时测量显示谷氨酸脱羧酶（mol. wt 67，000）蛋白（118%），以及免疫标记细胞的光密度（35%）。暴露后30天，两种谷氨酸脱羧酶亚型的下丘蛋白水平均显著低于未暴露对照组（65，000和67，000 mol.这些研究描述了在声暴露后立即增加的GABA标记物，随后在暴露后2至30天下降至低于对照水平。它仍然有待确定是否噪音创伤引起的变化，在下丘谷氨酸脱羧酶水平反映保护性上调，以应对强烈的刺激，其次是建立新的神经递质平衡水平。(C)1999年IBRO。出版社：Elsevier Science Ltd
The inferior colliculus is a central auditory structure which serves as a site for the integration of ascending and descending auditory information. Changes in central auditory structures may occur with acoustic exposure, which cannot be explained by alterations in cochlear function alone. Rats were exposed to a 10-kHz tone at 100 dB SPL for 9 h. Auditory brainstem response measures showed an initial 25-30-dB threshold shift across all tested frequencies. By 30 days post-exposure, thresholds for clicks and most frequencies returned to near control levels; however, thresholds remained elevated at 10 and 20 kHz. Inner hair cell loss was confined to apical and basal ends of the cochlea, and did not exceed 20%. Inferior colliculus levels of the two isoforms of the GABA synthetic enzyme glutamate decarboxylase (65,000 and 67,000 mol. wt forms) were measured immediately post-exposure (0 h) and at two and 30 days post-exposure using quantitative immunocytochemical and western blotting techniques. Zero-hour measures revealed a significant increase in the level of glutamate decarboxylase (mol. wt 67,000) protein (118%), as well as in the optical density (35%) of immunolabeled cells. By 30 days post-exposure, inferior colliculus protein levels of both glutamate decarboxylase isoforms were significantly below unexposed controls (39% and 21% for the 65,000 and 67,000 mol. wt forms, respectively).These studies describe increased markers for GABA immediately following acoustic exposure, followed by a decline to below control levels from two to 30 days post-exposure. It remains to be determined whether noise trauma-induced changes in glutamate decarboxylase levels in the inferior colliculus reflect protective up-regulation in response to intense stimulation, followed by the establishment of new neurotransmitter equilibrium levels. (C) 1999 IBRO. Published by Elsevier Science Ltd.