Synaptic activation and membrane potential changes modulate the frequency of spontaneous elementary Ca2+ release events in the dendrites of pyramidal neurons.
Synaptic activation and membrane potential changes modulate the frequency of spontaneous elementary Ca2+ release events in the dendrites of pyramidal neurons.
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DOI：
10.1523/jneurosci.0573-09.2009
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发表时间：
2009-06-17
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影响因子：
--
通讯作者：
Ross WN
中科院分区：
文献类型：
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作者：
Manita S;Ross WN
在大多数神经元中，突触后[Ca 2 +]i的变化是由突触激活打开电压门控通道、配体门控通道或动员细胞内储存的Ca 2+释放引起的。除了直接由刺激引起的这些变化之外，我们发现在锥体细胞中存在自发的、快速的Ca 2+释放事件，主要但不完全定位于树突状分支点。它们在主要的顶端树突上最清楚，但也在较细的分支和索马中检测到。通常，它们在起始时的空间范围约为2μm，上升时间小于15 ms，持续时间小于100 ms，振幅为反向传播动作电位在相同位置产生的振幅的10-70%。这些事件不是由于背景电或突触活动。然而，它们的速率可以通过中等频率的重复突触刺激来增加，主要是通过IP 3的代谢型谷氨酸受体动员。此外，它们的频率可以通过在阈下范围内膜电位的变化来调制，主要是通过影响Ca 2+通过L型通道进入。它们类似于由IP 3受体和兰尼碱受体介导的基本事件（“火花”和“喷”），这些受体主要在非神经元制剂中描述。这些自发的Ca ~（2+）释放事件可能是成熟神经元中某些突触后信号级联的基本单位。
In most neurons postsynaptic [Ca2+]i changes result from synaptic activation opening voltage gated channels, ligand gated channels, or mobilizing Ca2+ release from intracellular stores. In addition to these changes that result directly from stimulation we found that in pyramidal cells there are spontaneous, rapid, Ca2+ release events, predominantly, but not exclusively localized at dendritic branch points. They are clearest on the main apical dendrite but also have been detected in the finer branches and in the soma. Typically they have a spatial extent at initiation of about 2μm, a rise time of less than 15ms, duration less than 100ms, and amplitudes of 10-70% of that generated by a backpropagating action potential at the same location. These events are not due to background electrical or synaptic activity. However, their rate can be increased by repetitive synaptic stimulation at moderate frequencies, mainly through metabotropic glutamate receptor mobilization of IP3. In addition, their frequency can be modulated by changes in membrane potential in the subthreshold range, predominantly by affecting Ca2+ entry through L-type channels. They resemble the elementary events (“spark” and “puffs”) mediated by IP3 receptors and ryanodine receptors that have been described primarily in nonneuronal preparations. These spontaneous Ca2+ release events may be the fundamental units underlying some postsynaptic signaling cascades in mature neurons.