Somatic calcium level reports integrated spiking activity of cerebellar interneurons in vitro and in vivo
Somatic calcium level reports integrated spiking activity of cerebellar interneurons in vitro and in vivo
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DOI：
10.1152/jn.00133.2011
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发表时间：
2011-10-01
影响因子：
2.5
通讯作者：
Llano, Isabel
中科院分区：
文献类型：
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作者：
Franconville, Romain;Revet, Gaelle;Llano, Isabel
Franconville R，Revet G，阿斯托加G，Schwaller B，拉诺I.体细胞钙离子水平报告小脑中间神经元在体外和体内的整合尖峰活动。J Neurophysiol 106：1793-1805，2011.首次发表于2011年7月6日; doi：10.1152/jn.00133.2011.-本研究观察了成年小鼠小脑分子层中间神经元（MLI）胞体Ca（2+）信号与其放电活动的关系。使用双光子显微镜结合细胞贴附记录切片，我们表明，在紧张性发射MLI加载高亲和力Ca 2（2+）探针，Ca 2（2+）依赖的荧光瞬变是不存在的。以低速率加标的MLI的荧光迹线的加标触发平均值显示，与动作电位相关的荧光变化很小（基础荧光的1%）。为了揭示细胞内Ca 2（2+）浓度（[Ca（2+）]（i））和放电率之间的关系，用GABA A受体激动剂蝇蕈醇的喷烟短暂沉默尖峰。[Ca 2（2+）] i在单个指数后向基础水平松弛，其幅度与前一个峰频率相关。的弛豫时间常数是缓慢的（2.5秒）和独立的探针浓度。来自小白蛋白（PV）（-/-）动物的数据表明，PV控制尖峰触发平均值的幅度和衰减时间以及尖峰沉默后[Ca（2+）] i弛豫的时间过程。[Ca 2（2+）] i信号对L-型Ca 2（2+）通道阻断剂尼莫地平敏感，对ryanodine不敏感。在麻醉的小鼠中，如在切片中，来自大多数MLI的荧光迹线没有显示自发瞬变。尽管如此，他们响应蝇蕈醇离子电渗与放松类似的体外获得的，这表明一个状态的紧张性放电估计尖峰率范围从2到30赫兹。总之，[Ca 2（2+）] i信号似乎反映了MLI中尖峰活动的积分。我们建议蝇蕈醇沉默策略可以扩展到其他具有类似[Ca 2（2+）] i稳态的强直性尖峰神经元。
Franconville R, Revet G, Astorga G, Schwaller B, Llano I. Somatic calcium level reports integrated spiking activity of cerebellar interneurons in vitro and in vivo. J Neurophysiol 106: 1793-1805, 2011. First published July 6, 2011; doi: 10.1152/jn.00133.2011.-We examined the relationship between somatic Ca(2+) signals and spiking activity of cerebellar molecular layer interneurons ( MLIs) in adult mice. Using two-photon microscopy in conjunction with cell-attached recordings in slices, we show that in tonically firing MLIs loaded with high-affinity Ca2(2+) probes, Ca2(2+) -dependent fluorescence transients are absent. Spike-triggered averages of fluorescence traces for MLIs spiking at low rates revealed that the fluorescence change associated with an action potential is small ( 1% of the basal fluorescence). To uncover the relationship between intracellular Ca2(2+) concentration ([Ca(2+)](i)) and firing rates, spikes were transiently silenced with puffs of the GABA A receptor agonist muscimol. [Ca2(2+) ] i relaxed toward basal levels following a single exponential whose amplitude correlated to the preceding spike frequency. The relaxation time constant was slow ( 2.5 s) and independent of the probe concentration. Data from parvalbumin (PV)(-/-) animals indicate that PV controls the amplitude and decay time of spike-triggered averages as well as the time course of [Ca(2+)] i relaxations following spike silencing. The [Ca2(2+) ] i signals were sensitive to the L-type Ca2(2+) channel blocker nimodipine and insensitive to ryanodine. In anesthetized mice, as in slices, fluorescence traces from most MLIs did not show spontaneous transients. They nonetheless responded to muscimol iontophoresis with relaxations similar to those obtained in vitro, suggesting a state of tonic firing with estimated spiking rates ranging from 2 to 30 Hz. Altogether, the [Ca2(2+) ] i signal appears to reflect the integral of the spiking activity in MLIs. We propose that the muscimol silencing strategy can be extended to other tonically spiking neurons with similar [Ca2(2+) ] i homeostasis.