Astrocytic Gq-GPCR-Linked IP3R-Dependent Ca2+ Signaling Does Not Mediate Neurovascular Coupling in Mouse Visual Cortex In Vivo
Astrocytic Gq-GPCR-Linked IP3R-Dependent Ca2+ Signaling Does Not Mediate Neurovascular Coupling in Mouse Visual Cortex In Vivo
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DOI：
10.1523/jneurosci.2591-14.2014
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发表时间：
2014-09-24
影响因子：
5.3
通讯作者：
McCarthy, Ken D.
中科院分区：
文献类型：
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作者：
Bonder, Daniel E.;McCarthy, Ken D.
局部血流响应于神经元活动的变化模式而被调节（Roy和Sherrington，1890），该过程被称为神经血管耦合。已经提出，驱动这一过程的中央细胞通路是星形胶质细胞Gq-GPCR连接的IP 3R依赖性Ca 2+信号传导，尽管该假设的体内测试在很大程度上缺乏。我们研究了星形胶质细胞Gq-GPCR和IP 3R依赖性Ca 2+信号传导对清醒、轻度镇静、反应性小鼠皮质血流的影响，使用多光子激光扫描显微镜和新的遗传工具，使星形胶质细胞信号传导通路在体内的选择性操纵成为可能。星形胶质细胞Gq-GPCR级联和下游Ca 2+信号转导与hM 3Dq DREADD（设计师受体专门激活的设计师药物）设计师受体系统的选择性刺激不足以调节基底皮质血流。我们发现没有证据表明，可观察到的星形胶质细胞endfeet钙离子升高后，生理视觉刺激，尽管强大的扩张相邻的小动脉使用细胞GCaMP 3和LCK-GCaMP 6s，最敏感的钙离子指标。星形胶质细胞Ca 2+升高时，可以诱发意想不到的空气喷气引起的惊吓反应。然而，惊吓诱导的星形胶质细胞Ca 2+信号并不先于相应的惊吓诱导的血流动力学变化。此外，神经血管偶联在轻度镇静、反应性小鼠中是完整的，这些小鼠遗传上缺乏星形胶质细胞IP 3R依赖性Ca 2+信号传导（IP（3）R2 KO）。这些数据表明，星形胶质细胞Gq-GPCR-连接IP 3R依赖的Ca 2+信号传导不介导清醒，轻度镇静，响应小鼠的视觉皮层中的神经血管耦合。
Local blood flow is modulated in response to changing patterns of neuronal activity (Roy and Sherrington, 1890), a process termed neurovascular coupling. It has been proposed that the central cellular pathway driving this process is astrocytic Gq-GPCR-linked IP3R-dependent Ca2+ signaling, though in vivo tests of this hypothesis are largely lacking. We examined the impact of astrocytic Gq-GPCR and IP3R-dependent Ca2+ signaling on cortical blood flow in awake, lightly sedated, responsive mice using multiphoton laser-scanning microscopy and novel genetic tools that enable the selective manipulation of astrocytic signaling pathways in vivo. Selective stimulation of astrocytic Gq-GPCR cascades and downstream Ca2+ signaling with the hM3Dq DREADD (designer receptors exclusively activated by designer drugs) designer receptor system was insufficient to modulate basal cortical blood flow. We found no evidence of observable astrocyte endfeet Ca2+ elevations following physiological visual stimulation despite robust dilations of adjacent arterioles using cyto-GCaMP3 and Lck-GCaMP6s, the most sensitive Ca2+ indicator available. Astrocytic Ca2+ elevations could be evoked when inducing the startle response with unexpected air puffs. However, startle-induced astrocytic Ca2+ signals did not precede corresponding startleinduced hemodynamic changes. Further, neurovascular coupling was intact in lightly sedated, responsive mice genetically lacking astrocytic IP3R-dependent Ca2+ signaling (IP(3)R2 KO). These data demonstrate that astrocytic Gq-GPCR-linked IP3R-dependent Ca2+ signaling does not mediate neurovascular coupling in visual cortex of awake, lightly sedated, responsive mice.