Synaptic drive to motoneurons during fictive swimming in the developing zebrafish
Synaptic drive to motoneurons during fictive swimming in the developing zebrafish
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DOI：
10.1152/jn.2001.86.1.197
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发表时间：
2001-07-01
影响因子：
2.5
通讯作者：
Drapeau, P
中科院分区：
文献类型：
--
作者：
Buss, RR;Drapeau, P
研究并比较了斑马鱼麻痹幼鱼在模拟游泳过程中运动神经元的活动模式和游泳行为的发展。从幼虫孵化（2天后），第一次能够移动，到它们成为活跃的游泳者，能够捕捉猎物（4天后），研究幼虫。使用高速（500赫兹）视频成像对游泳进行基本行为表征。从孵化到第三天，幼虫很少游泳，而且没有方向。他们表现出持续的收缩爆发（“爆发游泳”），平均频率为60-70赫兹，持续时间从几秒到一分钟。到第4天，游泳已经成熟到更频繁和更不稳定的“跳动和滑动”模式，较慢的（类似35赫兹）的收缩频率大约为200毫秒，交替的滑动时间是原来的两倍，持续时间从几个周期到几分钟。在全细胞电流钳记录中，运动神经元表现出类似的兴奋性突触活动和放电模式，对应于有效的爆发游泳（第2-3天）或热滑游泳（第4天）。静息电位各阶段相似（约-70 mV），运动神经元去极化（约-40 mV），动作电位基本无超调。在模拟冲刺游泳中持续输入的频率和在模拟冲刺和滑翔游泳中重复输入的频率与行为收缩模式相对应。应用谷氨酸拮抗剂（kynurenic acid或6-cyano-7-nitroquinoxalene- 2,3-dione和DL-2-amino-5-phosphonovaleric acid）消除了游动活性模式，并在甘氨酸能拮抗剂士的宁的存在下进行了修饰，但保持了游动活性模式。在电压钳压下，运动神经元突触驱动的相应突触电流可被分离出来，由阳离子（谷氨酸能突触后电流）和阴离子输入（甘氨酸能突触后电流）组成。无论是持续或中断模式的PSCs分别观察在有效的爆发或热滑翔游泳。在热滑游泳过程中，观察到强直性内向电流和节律性谷氨酸能PSCs（类似于35 Hz）。相比之下，甘氨酸能PSCs的爆发频率更高，导致更紧张的模式，几乎没有同步活动的证据。我们得出结论，有节奏的谷氨酸能突触驱动是游泳的基础，而强直的、分流的甘氨酸能输入更紧密地将膜时间常数与快速突触驱动相匹配。
The development of swimming behavior and the correlated activity patterns recorded in motoneurons during fictive swimming in paralyzed zebrafish larvae were examined and compared. Larvae were studied from when they hatch (after 2 days) and are first capable of locomotion to when they are active swimmers capable of capturing prey (after 4 days). High-speed (500 Hz) video imaging was used to make a basic behavioral characterization of swimming. At hatching and up to day 3, the larvae swam infrequently and in an undirected fashion. They displayed sustained bursts of contractions ('burst swimming') at an average frequency of 60-70 Hz that lasted from several seconds to a minute in duration. By day 4 the swimming had matured to a more frequent and less erratic "beat-and-glide" mode, with slower (similar to 35 Hz) beats of contractions for similar to 200 ms alternating with glides that were twice as long, lasting from just a few cycles to several minutes overall. In whole cell current-clamp recordings, motoneurons displayed similar excitatory synaptic activity and firing patterns, corresponding to either fictive burst swimming (day 2-3) or beat-and-glide swimming (day 4). The resting potentials were similar at all stages (about -70 mV) and the motoneurons were depolarized (to about -40 mV) with generally non-overshooting action potentials during fictive swimming. The frequency of sustained inputs during fictive burst swimming and of repetitive inputs during fictive beat-and glide swimming corresponded to the behavioral contraction patterns. Fictive swimming activity patterns were eliminated by application of glutamate antagonists (kynurenic acid or 6-cyano-7-nitroquinoxalene- 2,3-dione and DL-2-amino-5-phosphonovaleric acid) and were modified but maintained in the presence of the glycinergic antagonist strychnine. The corresponding synaptic currents underlying the synaptic drive to motoneurons during fictive swimming could be isolated under voltage clamp and consisted of cationic [glutamatergic postsynaptic currents (PSCs)] and anionic inputs (glycinergic PSCs). Either sustained or interrupted patterns of PSCs were observed during fictive burst or beat-and-glide swimming, respectively. During beat-and-glide swimming, a tonic inward current and rhythmic glutamatergic PSCs (similar to 35 Hz) were observed. In contrast, bursts of glycinergic PSCs occurred at a higher frequency, resulting in a more tonic pattern with little evidence for synchronized activity. We conclude that a rhythmic glutamatergic synaptic drive underlies swimming and that a tonic, shunting glycinergic input acts to more closely match the membrane time constant to the fast synaptic drive.