Early development of respiratory motor circuits in larval zebrafish (Danio rerio)
Early development of respiratory motor circuits in larval zebrafish (Danio rerio)
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DOI：
10.1002/cne.25467
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发表时间：
2023-03-07
影响因子：
2.5
通讯作者：
Astad，Emma K.
中科院分区：
文献类型：
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作者：
McArthur，Kimberly L.;Tovar，Victoria M.;Astad，Emma K.
脊椎动物后脑中的节律产生回路与颅和脊髓运动神经元形成突触连接，产生协调的、有模式的呼吸行为。斑马鱼提供了一个独特的可处理的模型系统来研究体内呼吸运动回路发育的最早阶段。在斑马鱼的幼虫中，呼吸行为是由颅运动神经元支配的肌肉来完成的，包括面部分支运动神经元（fbmn），它支配着移动颚、口腔和盖的肌肉。然而，目前尚不清楚fbmn何时首次接受呼吸模式生成神经元的功能性突触输入，以及呼吸运动回路的功能输出在幼虫发育过程中如何变化。在当前的研究中，我们使用行为和钙成像来确定斑马鱼幼虫早期fbmn如何接收来自呼吸模式生成网络的功能性突触输入。斑马鱼在受精后3天（dpf）表现出有图案的包盖运动，尽管这种行为在4和5 dpf时变得更加一致。同样在3dpf中，fbmn根据神经活动模式分为两个不同的类别（“有节奏的”和“无节奏的”）。这两类神经元沿背腹侧轴排列不同，表明fbmn在3 dpf时已经建立了背腹侧地形。最后，在3 dpf时，被盖运动与胸鳍运动协调，表明被盖行为模式是由突触输入驱动的。综上所述，这些证据表明fbmn在3 dpf或之前开始接受来自功能性呼吸中枢模式发生器的初始突触输入。未来的研究将利用该模型来研究正常和异常呼吸回路发育的机制。
Rhythm‐generating circuits in the vertebrate hindbrain form synaptic connections with cranial and spinal motor neurons, to generate coordinated, patterned respiratory behaviors. Zebrafish provide a uniquely tractable model system to investigate the earliest stages in respiratory motor circuit development in vivo. In larval zebrafish, respiratory behaviors are carried out by muscles innervated by cranial motor neurons—including the facial branchiomotor neurons (FBMNs), which innervate muscles that move the jaw, buccal cavity, and operculum. However, it is unclear when FBMNs first receive functional synaptic input from respiratory pattern‐generating neurons, and how the functional output of the respiratory motor circuit changes across larval development. In the current study, we used behavior and calcium imaging to determine how early FBMNs receive functional synaptic inputs from respiratory pattern‐generating networks in larval zebrafish. Zebrafish exhibited patterned operculum movements by 3 days postfertilization (dpf), though this behavior became more consistent at 4 and 5 dpf. Also by 3dpf, FBMNs fell into two distinct categories (“rhythmic” and “nonrhythmic”), based on patterns of neural activity. These two neuron categories were arranged differently along the dorsoventral axis, demonstrating that FBMNs have already established dorsoventral topography by 3 dpf. Finally, operculum movements were coordinated with pectoral fin movements at 3 dpf, indicating that the operculum behavioral pattern was driven by synaptic input. Taken together, this evidence suggests that FBMNs begin to receive initial synaptic input from a functional respiratory central pattern generator at or prior to 3 dpf. Future studies will use this model to study mechanisms of normal and abnormal respiratory circuit development.