CENTRAL AUDITORY AGING - GABA CHANGES IN THE INFERIOR COLLICULUS
CENTRAL AUDITORY AGING - GABA CHANGES IN THE INFERIOR COLLICULUS
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DOI：
10.1016/0531-5565(94)00052-5
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发表时间：
1995-05-01
影响因子：
3.9
通讯作者：
HELFERT, RH
中科院分区：
文献类型：
--
作者：
CASPARY, DM;MILBRANDT, JC;HELFERT, RH
听觉相关性听力损失（老年性耳聋）是一种复杂的状态，反映了沿着整个听觉神经轴的病理变化。言语理解能力的丧失、声音定位能力的降低以及在噪声中检测和提取信号的能力的降低是老年人遇到的特征性问题。中枢性（神经性）老年性耳聋经常导致言语理解的急剧丧失，而纯音听阈没有相应的变化。尽管有证据表明，这些赤字不能完全解释的外周变化单独，很少有研究探讨了中枢听觉功能障碍的神经化学基础老化。参与声音信息处理的神经回路中的神经元相关改变可以反映神经递质的合成、降解、摄取、释放和受体敏感性的变化，可能继发于细胞丢失和/或进行性传入阻滞。一系列旨在验证这一假设的研究检查了F344大鼠中枢听觉系统的衰老。在一个重要的听觉中脑结构，下丘，与GABA神经递质功能相关的GABA相关的变化进行了研究。这些研究发现：（1）GABA免疫反应性神经元数量减少;（2）GABA基础水平（浓度）降低;（3）GABA释放减少;（4）谷氨酸脱羧酶活性降低;（5）GABA受体结合减少;（6）突触前末梢数量减少;（7）GABA受体结合轻微变化。总的来说，这些与年龄相关的变化表明IC中GABA神经递质功能的改变。识别在语音处理中重要的结构中的特定神经递质变化最终可能导致药物治疗选择性类型的年龄相关性听力损失的发展。
Age-related hearing loss (presbycusis) is a complex state that reflects pathologic changes along the entire auditory neuraxis. Loss of speech understanding, decreased ability to localize sounds, and a decreased ability to detect and extract signals in noise are characteristic problems encountered by the elderly. Central (neural) presbycusis frequently results in a dramatic loss in speech understanding without a parallel change in pure-tone thresholds. In spite of evidence that suggests these deficits cannot be fully explained by peripheral changes alone, few studies have examined the neurochemical basis of central auditory dysfunction in aging. Age-related alterations in neural circuits involved in the processing of acoustic information could reflect changes in the synthesis, degradation, uptake, release, and receptor sensitivity of neurotransmitters, perhaps secondary to cell loss and/or progressive deafferentation. A series of studies designed to test this hypothesis has examined aging in the central auditory system of the F344 rat. Age-related changes associated with GABA neurotransmitter function in an important auditory midbrain structure, the inferior colliculus, have been investigated. These studies found: (1) decreased numbers of GABA immunoreactive neurons; (2) decreased basal levels (concentrations) of GABA; (3) decreased GABA release; (4) decreased glutamic acid decarboxylase activity; (5) decreased GABA, receptor binding; (6) decreased numbers of presynaptic terminals; and (7) subtle GABA, receptor binding changes. Collectively, these age-related changes suggest altered GABA neurotransmitter function in the IC. Identification of specific neurotransmitter changes in structures important in speech processing could eventually lead to the development of pharmacotherapy for selective types of age-related hearing loss.