Mechanisms of dendritic calcium signaling in fly neurons
Mechanisms of dendritic calcium signaling in fly neurons
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DOI：
10.1152/jn.2001.85.1.439
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发表时间：
2001-01-01
影响因子：
2.5
通讯作者：
Borst, A
中科院分区：
文献类型：
--
作者：
Oertner, TG;Brotz, TM;Borst, A
我们研究了树突状钙在苍蝇视觉系统的小叶板切向细胞中积累的机制，使用了苍蝇大脑的体外制备。局部视觉刺激在体内唤起这些细胞树突中的局部钙信号。在这里，我们表明，通过局部离子渗透应用胆碱能激动剂碳醇，可以在体外引起类似的局部钙积累。钙信号至少有两个来源：第一，电压依赖性钙通道参与了碳水化合物诱导的信号，并集中在树突、体细胞和轴突的末端分支上。而碳乙醇刺激诱导的树突钙信号仅对膜去极化有微弱依赖性。树突钙信号的第二部分与电压无关，最可能的解释是钙通过烟碱乙酰胆碱受体进入。我们没有发现第二信使或钙介导的钙从细胞内储存释放的迹象。综上所述，小叶板切向细胞树突中特征性的时空钙信号可以在体外复制，并且是电压和配体门控钙内流共同作用的结果。
We examined the mechanisms underlying dendritic calcium accumulation in lobula plate tangential cells of the fly visual system using an in vitro preparation of the fly brain. Local visual stimulation evokes a localized calcium signal in the dendrites of these cells in vivo. Here we show that a similar localized calcium accumulation can be elicited in vitro by focal iontophoretic application of the cholinergic agonist carbachol. The calcium signal had at least two sources: first, voltage-dependent calcium channels contributed to the carbachol-induced signal and were concentrated on the dendrite, the soma, and the terminal ramification of the axon. However, the dendritic calcium signal induced by carbachol stimulation was only weakly dependent on membrane depolarization. The most likely explanation for the second, voltage-independent part of the dendritic calcium signal is calcium entry through nicotinic acetylcholine receptors. We found no indication of second-messenger or calcium-mediated calcium release from intracellular stores. In summary, the characteristic spatiotemporal calcium signals in the dendrites of lobula plate tangential cells can be reproduced in vitro, and result from a combination of voltage- and ligand-gated calcium influx.