Excitatory modulation in the cochlear nucleus through group I metabotropic glutamate receptor activation.
Excitatory modulation in the cochlear nucleus through group I metabotropic glutamate receptor activation.
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DOI：
10.1523/jneurosci.1193-11.2011
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发表时间：
2011-05-18
期刊：
影响因子：
--
通讯作者：
Xu-Friedman MA
中科院分区：
文献类型：
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作者：
Chanda S;Xu-Friedman MA
已经表明I组代谢型谷氨酸受体（mGluRs）的激活调节听觉神经元的发育。然而，mGluR激活对生理反应性质的急性影响尚不清楚。为了解决这个问题，我们研究了mGluRs在哺乳动物前腹侧耳蜗核（AVCN）的丛状细胞（BC）的影响。用二羟苯甘氨酸（DHPG）激活mGluRs可引起与P42一样大的小鼠BCs去极化，但不影响突触前听神经（AN）纤维的神经递质释放。mGluR拮抗剂的应用表明，mGluR具有张力活性，并且对谷氨酸再摄取阻断剂苏-β-苄氧基天冬氨酸（TBOA）引起的环境谷氨酸的小幅升高高度敏感。mGluR介导的去极化增强了对AN刺激的响应概率，并减少了延迟和抖动。此外，通过突触后mGluRs的兴奋可以显著抵消突触前GABAB受体的抑制作用。因此，这两种调节途径之间的相互作用可以为微调BC中继提供额外的灵活性。
Activation of group I metabotropic glutamate receptors (mGluRs) has been suggested to modulate development of auditory neurons. However, the acute effects of mGluR activation on physiological response properties are unclear. To address this, we studied the effects of mGluRs in bushy cells (BCs) of the mammalian anteroventral cochlear nucleus (AVCN). Activation of mGluRs with dihydroxyphenylglycine (DHPG) caused depolarization of BCs in mice as old as P42, but did not affect neurotransmitter release by presynaptic auditory nerve (AN) fibers. Application of mGluR antagonists indicated that mGluRs are tonically active, and are highly sensitive to small elevations in ambient glutamate by the glutamate reuptake blocker threo-β-benzyloxyaspartic acid (TBOA). mGluR-mediated depolarization enhanced the firing probability in response to AN stimulation, and reduced the latency and jitter. Furthermore, excitation through postsynaptic mGluRs can significantly counter-balance the inhibitory effects of presynaptic GABAB receptors. Thus, interaction between these two modulatory pathways may provide additional flexibility for fine-tuning the BC relay.