Chang T N, Keshishian H
Interdepartmental Neuroscience Program, Yale University, New Haven, Connecticut 06520-8103, USA.
J Neurosci. 1996 Sep 15;16(18):5715-26. doi: 10.1523/JNEUROSCI.16-18-05715.1996.
We have tested the effects of neuromuscular denervation in Drosophila by laser-ablating the RP motoneurons in intact embryos before synaptogenesis. We examined the consequences of this ablation on local synaptic connectivity in both 1st and 3rd instar larvae. We find that the partial or complete loss of native innervation correlates with the appearance of alternate inputs from neighboring motor endings and axons. These collateral inputs are found at ectopic sites on the denervated target muscle fibers. The foreign motor endings are electrophysiologically functional and are observed on the denervated muscle fibers by the 1st instar larval stage. Our data are consistent with the existence of a local signal from the target environment, which is regulated by innervation and influences synaptic connectivity. Our results show that, despite the stereotypy of Drosophila neuromuscular connections, denervation can induce local changes in connectivity in wild-type Drosophila, suggesting that mechanisms of synaptic plasticity may also be involved in normal Drosophila neuromuscular development.
我们通过在完整胚胎的突触形成之前用激光消融RP运动神经元，测试了果蝇神经肌肉去神经支配的影响。我们研究了这种消融对一龄和三龄幼虫局部突触连接的影响。我们发现，天然神经支配的部分或完全丧失与来自相邻运动终末和轴突的替代输入的出现相关。这些侧支输入出现在去神经支配的靶肌肉纤维的异位部位。外来运动终末在电生理上是有功能的，并且在一龄幼虫阶段就可以在去神经支配的肌肉纤维上观察到。我们的数据与来自靶环境的局部信号的存在一致，该信号受神经支配调节并影响突触连接。我们的结果表明，尽管果蝇神经肌肉连接具有刻板性，但去神经支配可以在野生型果蝇中诱导连接性的局部变化，这表明突触可塑性机制可能也参与了正常果蝇神经肌肉发育。
