Threshold conditions for synaptically evoking Ca(2+) waves in hippocampal pyramidal neurons.
Threshold conditions for synaptically evoking Ca(2+) waves in hippocampal pyramidal neurons.
复制标题
海马锥体神经元突触诱发 Ca(2) 波的阈值条件。
DOI：
10.1152/jn.00601.2001
复制
发表时间：
2002
影响因子：
2.5
通讯作者：
Ross,WilliamN
中科院分区：
文献类型：
--
作者：
Zhou,Suya;Ross,WilliamN
三磷酸肌醇（IP3）敏感的细胞内钙以钙波的形式释放，导致海马CA1区锥体神经元顶树突内[Ca 2 +] i大幅度增加。在I组代谢型谷氨酸（mGlu）受体的突触激活后产生释放。我们系统地研究了唤起这些波在横向切片2至3周龄大鼠的条件。使用放置在放射层中的尖锐的非对称双极钨刺激电极，我们改变电极的横向位置、刺激脉冲的数量、训练频率和刺激电流。有几个趋势是明确的。将刺激频率从20 Hz增加到100 Hz，保持脉冲总数恒定，降低了所需的刺激电流。频率低于20 Hz的刺激很难引起释放。增加刺激脉冲的数量，保持频率恒定，降低阈值电流。至少需要5个100 Hz的脉冲才能可靠地诱发释放，但记录了3个脉冲成功的几个例子。Theta爆发刺激与强直刺激一样有效。将刺激电极的尖端放置在离锥体神经元更近的地方，更容易诱发释放，尽管用不锋利的电极在500 μm的横向距离处进行刺激有时会成功。对这些结果的最简单的解释是，必须在树突的有限区域中快速产生IP 3团以产生Ca 2+波。诱发再生Ca2+释放所需的条件与强直刺激后这些细胞中诱发长时程增强所需的条件有许多相似之处（和一些差异）。
Regenerative Ca2+release from inositol 1,4,5-trisphosphate (IP3)-sensitive intracellular stores in the form of Ca2+waves leads to large-amplitude [Ca2+]iincreases in the apical dendrites of hippocampal CA1 pyramidal neurons. Release is generated following synaptic activation of group I metabotropic glutamate (mGlu) receptors. We systematically examined the conditions for evoking these waves in transverse slices from 2- to 3-wk-old rats. Using a sharpened asymmetrical bipolar tungsten stimulating electrode placed in the stratum radiatum, we varied the lateral position of the electrode, the number of stimulating pulses, the train frequency, and stimulus current. Several trends were clear. Increasing the frequency of stimulation from 20 to 100 Hz, keeping the total number of pulses constant, lowered the required stimulus current. Stimulation at frequencies below 20 Hz made it difficult to evoke release. Increasing the number of stimulation pulses, keeping the frequency constant, lowered the threshold current. A minimum of five pulses at 100 Hz was required to evoke release reliably, but several examples of success with three pulses were recorded. Theta-burst stimulation was as effective as tetanic stimulation. Placing the point of the stimulation electrode closer to the pyramidal neuron made it easier to evoke release, although stimulation at a lateral distance of 500 μm with unsharpened electrodes was sometimes successful. The simplest explanation for these results is that a bolus of IP3must be produced quickly in a restricted region of the dendrites to generate Ca2+waves. The conditions necessary for evoking regenerative Ca2+release have many parallels (and some differences) with the conditions required to evoke long-term potentiation in these cells following tetanic stimulation.