Effect of common anesthetics on dendritic properties in layer 5 neocortical pyramidal neurons
Effect of common anesthetics on dendritic properties in layer 5 neocortical pyramidal neurons
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DOI：
10.1152/jn.01126.2007
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发表时间：
2008-03-01
影响因子：
2.5
通讯作者：
Larkum, Matthew E.
中科院分区：
文献类型：
--
作者：
Potez, Sarah;Larkum, Matthew E.
迄今为止，了解活性树突特性对体内网络活性的影响仅限于麻醉动物的研究。然而，迄今为止还没有研究确定麻醉剂本身对树突特性的直接影响。在这里，我们研究了动物实验中常用的三种麻醉剂（乌拉坦、戊巴比妥和氯胺酮/甲苯噻嗪）的作用。我们研究了产生的钙峰，动作电位（AP）的传播沿着的顶树突和躯体放电特性在体外麻醉剂的存在下，使用双体树突全细胞记录。树突状电流注入和索马处的AP高频串诱发钙峰。令人惊讶的是，我们发现麻醉剂对钙峰的直接作用非常不同。两种麻醉剂（乌拉坦和戊巴比妥）抑制树突状细胞的钙峰在体外，而氯胺酮和甲苯噻嗪的混合物增强它们。尖峰沿着树突的传播没有受到任何麻醉剂的显著影响，但是在体细胞放电特性中存在高度依赖于麻醉剂的各种变化。最后，我们研究了麻醉剂对钙峰的启动和持续时间在体内使用在细胞体产生的AP的高频列车的影响。我们发现相同的麻醉依赖性的直接影响，除了整体减少树突兴奋性在麻醉大鼠与所有三种麻醉剂相比，切片制备。
Understanding the impact of active dendritic properties on network activity in vivo has so far been restricted to studies in anesthetized animals. However, to date no study has been made to determine the direct effect of the anesthetics themselves on dendritic properties. Here, we investigated the effects of three types of anesthetics commonly used for animal experiments (urethane, pentobarbital and ketamine/xylazine). We investigated the generation of calcium spikes, the propagation of action potentials (APs) along the apical dendrite and the somatic firing properties in the presence of anesthetics in vitro using dual somatodendritic whole cell recordings. Calcium spikes were evoked with dendritic current injection and high-frequency trains of APs at the soma. Surprisingly, we found that the direct actions of anesthetics on calcium spikes were very different. Two anesthetics (urethane and pentobarbital) suppressed dendritic calcium spikes in vitro, whereas a mixture of ketamine and xylazine enhanced them. Propagation of spikes along the dendrite was not significantly affected by any of the anesthetics but there were various changes in somatic firing properties that were highly dependent on the anesthetic. Last, we examined the effects of anesthetics on calcium spike initiation and duration in vivo using high-frequency trains of APs generated at the cell body. We found the same anesthetic-dependent direct effects in addition to an overall reduction in dendritic excitability in anesthetized rats with all three anesthetics compared with the slice preparation.