Target-specific regulation of presynaptic release properties at auditory nerve terminals in the avian cochlear nucleus.
Target-specific regulation of presynaptic release properties at auditory nerve terminals in the avian cochlear nucleus.
复制标题
鸟类耳蜗核听觉神经末梢突触前释放特性的目标特异性调节。
DOI：
10.1152/jn.00752.2015
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发表时间：
2016
影响因子：
2.5
通讯作者：
MacLeod,KM
中科院分区：
文献类型：
--
作者：
Ahn,J;MacLeod,KM
短期突触可塑性（STP）充当时间和放电率依赖的过滤器，介导跨突触的信息传输。在听觉脑干中，编码声音时序和强度信息的不同通路表达不同的 STP。为了研究哪些因素决定了不同末端表达的可塑性，我们测试了听觉神经投射到鸟类耳蜗核（角核（NA）和大细胞核（NM）的两个部分）的突触前释放概率是否不同。使用 N-甲基-d-天冬氨酸 (NMDA) 受体的开放通道阻断剂对释放概率进行了估计。使用 20 μM (+)-MK801 马来酸盐对 NMDA 受体介导的兴奋性突触后电流 (EPSC) 的活性依赖性阻断在 NM 中比在 NA 中更快，表明 NM 中末端的释放概率显着更高。配对脉冲比 (PPR) 与 NA 末端的封锁率密切相关，表明 PPR 是这些突触相对释放概率的合理代表。为了测试 NA 神经元的收敛输入之间的释放概率是否相似，测量了同一突触后 NA 目标神经元的不同神经输入的 PPR。 PPR 以及短训练期间的可塑性在多个输入之间紧密相关，进一步表明听觉神经末梢的释放概率以特定目标的方式进行协调。听觉脑干中 STP 的这种高度特异性调节提供了证据，表明突触动力学被调整以将神经活动中的听觉信息差异传输到平行的上行通路中。
Short-term synaptic plasticity (STP) acts as a time- and firing rate-dependent filter that mediates the transmission of information across synapses. In the auditory brain stem, the divergent pathways that encode acoustic timing and intensity information express differential STP. To investigate what factors determine the plasticity expressed at different terminals, we tested whether presynaptic release probability differed in the auditory nerve projections to the two divisions of the avian cochlear nucleus, nucleus angularis (NA) and nucleus magnocellularis (NM). Estimates of release probability were made with an open-channel blocker ofN-methyl-d-aspartate (NMDA) receptors. Activity-dependent blockade of NMDA receptor-mediated excitatory postsynaptic currents (EPSCs) with application of 20 μM (+)-MK801 maleate was more rapid in NM than in NA, indicating that release probability was significantly higher at terminals in NM. Paired-pulse ratio (PPR) was tightly correlated with the blockade rate at terminals in NA, suggesting that PPR was a reasonable proxy for relative release probability at these synapses. To test whether release probability was similar across convergent inputs onto NA neurons, PPRs of different nerve inputs onto the same postsynaptic NA target neuron were measured. The PPRs, as well as the plasticity during short trains, were tightly correlated across multiple inputs, further suggesting that release probability is coordinated at auditory nerve terminals in a target-specific manner. This highly specific regulation of STP in the auditory brain stem provides evidence that the synaptic dynamics are tuned to differentially transmit the auditory information in nerve activity into parallel ascending pathways.