Depression of synaptic efficacy at intermolt in crayfish neuromuscular junctions by 20-hydroxyecdysone, a molting hormone
Depression of synaptic efficacy at intermolt in crayfish neuromuscular junctions by 20-hydroxyecdysone, a molting hormone
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DOI：
10.1152/jn.1998.79.4.1931
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发表时间：
1998-04-01
影响因子：
2.5
通讯作者：
Ruffner, ME
中科院分区：
文献类型：
--
作者：
Cooper, RL;Ruffner, ME
这份报告表明，蜕皮类固醇可以通过作用于突触前部位，减少甲壳类紧张性神经肌肉接头间质阶段的突触传递。类固醇蜕皮激素20-羟基蜕皮酮(20-HE)似乎通过一种快速的非基因组机制发挥作用，这种机制减少了突触小泡释放的可能性，减少了释放部位的数量。量化分析显示，当20-HE存在时，对于给定的刺激，释放的囊泡更少，这反过来解释了诱人的突触效率。突触效能降低导致诱发的突触后电流和跨肌纤维膜的兴奋性突触后电位(EPSPS)变小。在由高或低输出终末支配的肌肉纤维中观察到EPSPS的减少。甲壳动物/小龙虾在蜕皮周期中的行为，当20-HE含量较高时，可能是由于突触传递的减少。甲壳类动物和昆虫一样，在蜕皮前阶段变得静止。20-HE的作用可以通过应用甲壳类神经调节剂5-羟色胺来逆转，它可以增强突触传递。
This report demonstrates that ecdysteroids can reduce synaptic transmission at an intermolt stage of a crustacean tonic neuromuscular junction by acting at a presynaptic site. The steroid molting hormone, 20-hydroxyecdysone (20-HE), appears to act through a rapid, nongenomic mechanism that decreases the probability of synaptic vesicle release and reduces the number of release sites. Quantal analysis revealed that fewer vesicles were released for a given stimulus when 20-HE was present, and this in turn accounted for the seduced synaptic efficacy. Reduced synaptic efficacy produced smaller evoked postsynaptic currents and smaller excitatory postsynaptic potentials (EPSPs) across the muscle fiber membrane. The reduction in EPSPs was observed among muscle fibers that were innervated by high-or low-output terminals. The behavior of crustaceans/crayfish during the molt cycle, when 20-HE is high, may be explained by the reduction in synaptic transmission. Crustaceans become quiescent during the premolt periods as do insects. The effects of 20-HE can be reversed with the application of the crustacean neuromodulator serotonin, which enhances synaptic transmission.