Inter- and intra-specific differences in muscarinic acetylcholine receptor expression in the neural pathways for vocal learning in songbirds
Inter- and intra-specific differences in muscarinic acetylcholine receptor expression in the neural pathways for vocal learning in songbirds
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DOI：
10.1002/cne.24532
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发表时间：
2018-12-01
影响因子：
2.5
通讯作者：
Wada, Kazuhiro
中科院分区：
文献类型：
--
作者：
Asogwa, Norman C.;Mori, Chihiro;Wada, Kazuhiro
乙酰胆碱受体（AChRs）广泛存在于脊椎动物的中枢神经系统中。毒蕈碱型乙酰胆碱受体（mAChRs）是乙酰胆碱受体的一个功能亚类，通过细胞内信号转导介导神经元的反应。它们还通过增强皮层可塑性在感觉运动协调和运动技能学习中发挥作用。学习性鸟鸣是一种复杂的运动技能，通过在关键时期的感觉运动协调获得。然而，AChRs在发声学习和产生的神经回路中的功能在很大程度上仍未被探索。在这里，我们报告的独特的表达mAChRs亚基（chrm2 - 5）在斑胸草雀的鸣唱核。与周围的脑区相比，兴奋性亚基（chrm3和chrm5）的表达在鸣唱核团中下调。相比之下，相对于周围的巢皮质，运动前歌唱核HVC中抑制性mAChR（chrm 2和chrm 4）的表达上调。Chrm4在HVC中的表达在关键期呈现发育性差异。与chrm4相比，chrm2在HVC中的表达在关键期早期出现个体差异。尽管给予睾酮或听觉剥夺改变了歌曲稳定的时间，这些chrm2表达的个体差异仍然存在。相反，HVC中chrm2表达的变异性与亲本遗传学相关。此外，chrm2在HVC中的表达表现出鸣禽物种之间的物种差异和个体变异性。这些结果表明，mAChRs通过调节HVC神经元的兴奋性，在歌曲模式的物种和个体差异的发展中发挥了未被充分认识的作用，为HVC神经元听觉反应的门控提供了潜在的见解。
Acetylcholine receptors (AChRs) abound in the central nervous system of vertebrates. Muscarinic AChRs (mAChRs), a functional subclass of AChRs, mediate neuronal responses via intracellular signal transduction. They also play roles in sensorimotor coordination and motor skill learning by enhancing cortical plasticity. Learned birdsong is a complex motor skill acquired through sensorimotor coordination during a critical period. However, the functions of AChRs in the neural circuits for vocal learning and production remain largely unexplored. Here, we report the unique expression of mAChRs subunits (chrm2-5) in the song nuclei of zebra finches. The expression of excitatory subunits (chrm3 and chrm5) was downregulated in the song nuclei compared with the surrounding brain regions. In contrast, the expression of inhibitory mAChRs (chrm2 and chrm4) was upregulated in the premotor song nucleus HVC relative to the surrounding nidopallium. Chrm4 showed developmentally different expression in HVC during the critical period. Compared with chrm4, individual differences in chrm2 expression emerged in HVC early in the critical period. These individual differences in chrm2 expression persisted despite testosterone administration or auditory deprivation, which altered the timing of song stabilization. Instead, the variability in chrm2 expression in HVC correlated with parental genetics. In addition, chrm2 expression in HVC exhibited species differences and individual variability among songbird species. These results suggest that mAChRs play an underappreciated role in the development of species and individual differences in song patterns by modulating the excitability of HVC neurons, providing a potential insight into the gating of auditory responses in HVC neurons.