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首页> 外文期刊>Journal of Neurophysiology >Metabotropic glutamate receptor activation modulates sound level processing in the cochlear nucleus.
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Metabotropic glutamate receptor activation modulates sound level processing in the cochlear nucleus.

机译：代谢型谷氨酸受体激活调节耳蜗核中的声级处理。

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The principal role of ionotropic glutamate receptors in the transmission and processing of information in the auditory pathway has been investigated extensively. In contrast, little is known about the functional contribution of the G-protein-coupled metabotropic glutamate receptors (mGluRs), although their anatomic location suggests that they exercise a significant influence on auditory processing. To investigate this issue, sound-evoked responses were obtained from single auditory neurons in the cochlear nuclear complex of anesthetized cats and gerbils, and metabotropic ligands were administered locally through microionophoretic pipettes. In general, microionophoresis of the mGluR agonists, (1S, 3R)-1-aminocyclopentane-1,3-dicarboxylic acid or (2S,1'S, 2'S)-2-(carboxycyclopropyl)glycine, initially produced a gradual increase in spontaneous and sound-evoked discharge rates. However, activation and recovery times were significantly longer than those observed for ionotropic agonists, such as N-methyl--aspartate or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, consistent with the recruitment of a second-messenger system. The efficacy of mGluR agonists was diminished after administration of the mGluR antagonist, (+)-alpha-methyl-4-carboxyphenylglycine, consistent with a selective action at metabotropic recognition sites. In contrast, two distinct changes were observed after the mGluR agonist had been discontinued for several minutes. Approximately 50% of neurons exhibited a chronic depression of sound-evoked discharge rate reminiscent of long-term depression, a cellular property observed in other systems. Approximately 30% of neurons exhibited a long-lasting enhancement of the sound-evoked response similar to the cellular phenomenon of long-term potentiation. These findings suggest that mGluR activation has a profound influence on the gain of primary afferent driven activity in the caudal cochlear nucleus.
机译：离子型谷氨酸受体在听觉途径中信息的传递和处理中的主要作用已得到广泛研究。相比之下，对G蛋白偶联的代谢型谷氨酸受体（mGluRs）的功能贡献知之甚少，尽管它们的解剖位置表明它们对听觉加工有重要影响。为了研究这个问题，从麻醉的猫和沙鼠的耳蜗核复合物中的单个听觉神经元获得了诱发声音的反应，并通过微离子移液管局部施用了代谢型配体。通常，mGluR激动剂（（1S，3R）-1-氨基环戊烷-1，3-二羧酸或（2S，1'S，2'S）-2-（羧基环丙基）甘氨酸）的微离子电泳最初产生的自发性和声音逐渐增加诱发放电率。但是，活化和恢复时间比离子型激动剂（如N-甲基天门冬氨酸或α-氨基-3-羟基-5-羟基-5-甲基-4-异恶唑丙酸）所观察到的要长得多，这与第二种激动剂的募集相符。信使系统。施用mGluR拮抗剂（+）-α-甲基-4-羧基苯基甘氨酸后，mGluR激动剂的功效减弱，这与在代谢型识别位点的选择性作用一致。相反，在将mGluR激动剂中断几分钟后，观察到两个明显的变化。大约50％的神经元表现出声音诱发的放电率的慢性抑制，使人联想到长期压抑，这是在其他系统中观察到的细胞特性。大约30％的神经元表现出类似于长期增强细胞现象的声音诱发反应的持久增强。这些发现表明，mGluR激活对尾蜗耳蜗核初级传入驱动活动的获得具有深远的影响。

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