Optogenetic activation of LiGluR-expressing astrocytes evokes anion channel-mediated glutamate release
Optogenetic activation of LiGluR-expressing astrocytes evokes anion channel-mediated glutamate release
复制标题
DOI：
10.1113/jphysiol.2011.219345
复制
发表时间：
2012-02-01
影响因子：
5.5
通讯作者：
Ropert, Nicole
中科院分区：
文献类型：
--
作者：
Li, Dongdong;Herault, Karine;Ropert, Nicole
星形胶质细胞Ca2+的增加被认为可以引起胶质递质释放，然而，释放的机制，这种递质的身份，甚至这种释放是否和何时发生，都是有争议的，主要是由于缺乏一种选择性和可重复刺激电沉默星形胶质细胞的方法。在培养的皮质星形胶质细胞中，光门控Ca2+可渗透的嗜离子性GluR6谷氨酸受体（LiGluR）的光激活，以及在较小程度上新的Ca2+易位通道rhodopsin CatCh，比突变通道rhodopsin 2 ChR2（H134R）唤起更可靠的Ca2+升高。我们使用倏逝场激发进行近膜Ca2+成像，并使用表观荧光激活和灭活LiGluR。通过交替激活和失活光脉冲，liglur诱发的Ca2+升高可以在幅度和持续时间上分级。表达liglur的星形胶质细胞的光刺激诱发了谷氨酸介导的概率信号传导到相邻的不表达liglur的星形胶质细胞。这种星形胶质细胞到星形胶质细胞的信号传导对囊泡释放、半通道和谷氨酸转运蛋白的失活不敏感，对阴离子通道阻滞剂敏感。我们的研究结果表明，LiGluR是一种选择性和可重复性激活星形胶质细胞的强大工具。
Increases in astrocyte Ca2+ have been suggested to evoke gliotransmitter release, however, the mechanism of release, the identity of such transmitter(s), and even whether and when such release occurs, are controversial, largely due to the lack of a method for selective and reproducible stimulation of electrically silent astrocytes. Here we show that photoactivation of the light-gated Ca2+-permeable ionotropic GluR6 glutamate receptor (LiGluR), and to a lesser extent the new Ca2+-translocating channelrhodopsin CatCh, evokes more reliable Ca2+ elevation than the mutant channelrhodopsin 2, ChR2(H134R) in cultured cortical astrocytes. We used evanescent-field excitation for near-membrane Ca2+ imaging, and epifluorescence to activate and inactivate LiGluR. By alternating activation and inactivation light pulses, the LiGluR-evoked Ca2+ rises could be graded in amplitude and duration. The optical stimulation of LiGluR-expressing astrocytes evoked probabilistic glutamate-mediated signalling to adjacent LiGluR-non-expressing astrocytes. This astrocyte-to-astrocyte signalling was insensitive to the inactivation of vesicular release, hemichannels and glutamate-transporters, and sensitive to anion channel blockers. Our results show that LiGluR is a powerful tool to selectively and reproducibly activate astrocytes.