Temperature dependent modulation of lobster neuromuscular properties by serotonin
Temperature dependent modulation of lobster neuromuscular properties by serotonin
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DOI：
10.1242/jeb.02717
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发表时间：
2007-03-15
影响因子：
2.8
通讯作者：
Worden, Mary Kate
中科院分区：
文献类型：
--
作者：
Hamilton, Jonna L.;Edwards, Claire R.;Worden, Mary Kate
在冷血动物中，神经肌肉功能的功效取决于动物栖息地的热环境和动物体内循环的调节激素的浓度。本研究的目的是研究如何在生态相关的范围内的温度变化影响神经肌肉功能和神经激素5-羟色胺（5-HT）在Homarus americanus，龙虾物种，栖息在野外的广泛的热范围内的调制。神经支配龙虾指叉肌的兴奋性和抑制性运动神经元的突触强度取决于温度，在冷（< 5摄氏度）温度下引起最强的神经诱发的肌肉运动。然而，尽管神经诱发的收缩可以在2至> 20摄氏度的整个温度范围内引起，但静息肌张力的神经诱发的松弛仅在抑制性接点电位极性超极化的较低温度下有效。5-HT对抑制性突触信号有两种作用：它增强它们的振幅，并使它们反转极性的温度改变约+7 ℃。因此，5-HT既增强了神经诱发的肌肉松弛，又增加了神经诱发的肌肉松弛可以被引发的温度范围。神经诱发的收缩在温暖（18摄氏度）的温度下最大限度地增强5-HT，然而，5-HT增强兴奋性连接电位的温度无关的方式。最后，5-HT在测试温度范围的最冷程度（2摄氏度）下强烈增加静息肌张力，但在22摄氏度下无效。这些数据表明，5-HT elevants几个温度依赖性的生理变化的被动和主动反应的肌肉神经输入。5-HT的总体作用是增加在该神经肌肉系统中可以引起神经诱发运动的温度范围。
In cold-blooded species the efficacy of neuromuscular function depends both on the thermal environmental of the animal's habitat and on the concentrations of modulatory hormones circulating within the animal's body. The goal of this study is to examine how temperature variation within an ecologically relevant range affects neuromuscular function and its modulation by the neurohormone serotonin (5-HT) in Homarus americanus, a lobster species that inhabits a broad thermal range in the wild. The synaptic strength of the excitatory and inhibitory motoneurons innervating the lobster dactyl opener muscle depends on temperature, with the strongest neurally evoked muscle movements being elicited at cold (< 5 degrees C) temperatures. However, whereas neurally evoked contractions can be elicited over the entire temperature range from 2 to > 20 degrees C, neurally evoked relaxations of resting muscle tension are effective only at colder temperatures at which the inhibitory junction potentials are hyperpolarizing in polarity. 5-HT has two effects on inhibitory synaptic signals: it potentiates their amplitude and also shifts the temperature at which they reverse polarity by approximately +7 degrees C. Thus 5-HT both potentiates neurally evoked relaxations of the muscle and increases the temperature range over which neurally evoked muscle relaxations can be elicited. Neurally evoked contractions are maximally potentiated by 5-HT at warm (18 degrees C) temperatures; however, 5-HT enhances excitatory junction potentials in a temperature-independent manner. Finally, 5-HT strongly increases resting muscle tension at the coldest extent of the temperature range tested (2 degrees C) but is ineffective at 22 degrees C. These data demonstrate that 5-HT elicits several temperature-dependent physiological changes in the passive and active responses of muscle to neural input. The overall effect of 5-HT is to increase the temperature range over which neurally evoked motor movements can be elicited in this neuromuscular system.