【罂粟通知】快发放中间神经元与丙泊酚诱导的大鼠岛状皮层锥体神经元的放电同步有关
快发放中间神经元与丙泊酚诱导的大鼠岛状皮层锥体神经元的放电同步有关
使用意识丧失剂量的全身麻醉药物丙泊酚时，可诱导大脑皮层中的额叶节律。本研究作者假设，在丙泊酚诱导的易化作用下，单位抑制性突触后电流将导致突触后锥体神经元之间的放电同步，而这些神经元受到相同的突触前抑制性快发放神经元抑制。
在大鼠岛状皮质切片中，从一个快发放神经元和两个或三个具有至少两个抑制性连接的锥体神经元进行了多个全细胞膜片钳记录。作者研究了未使用10μM丙泊酚和使用期间，来自突触前快发放神经元的抑制性输入如何调节锥体神经元之间自发性重复尖峰发射的时间。
接受突触前快发放神经元以150毫秒间期发放的共同抑制输入信号的锥体细胞显示出，与丙泊酚依赖的在同一直线的平均距离减小的特性，这可评估锥体神经元之间的峰时序变异系数：在首次激活快发放神经元之后距同一直线的平均距离，对照组中为29.2±24.1（均数±标准差，绝对值），丙泊酚使用期间组为19.7±19.2（P <0.001） 。在不激活快发放神经元的情况下以及在没有突触前快发放神经元的共同抑制输入的锥体神经元对中，丙泊酚不会改变距同一直线的平均距离。当突触前快发放神经元分别以6.7和10 Hz激活，而不是以1、4和13.3 Hz激活时，丙泊酚分别将同步指数从1.4±0.5增加到2.3±1.5（绝对值，P = 0.004）和1.5±0.5增加到2.2±1.0（P = 0.030）。其中同步指数是反映锥体神经元之间的尖峰同步程度。
以上结果表明，丙泊酚可通过增强快发放神经元的抑制性输入促进锥体神经元的放电同步。锥体神经元的这种同步性可能与丙泊酚引起意识丧失的脑电α节律有关。
Fast-spiking Interneurons Contribute to Propofol-induced Facilitation of Firing Synchrony in Pyramidal Neurons of the Rat Insular Cortex
Background: The general anesthetic propofol induces frontal alpha rhythm in the cerebral cortex at a dose sufficient to induce loss of consciousness. The authors hypothesized that propofol-induced facilitation of unitary inhibitory postsynaptic currents would result in firing synchrony among postsynaptic pyramidal neurons that receive inhibition from the same presynaptic inhibitory fast-spiking neurons.
Methods: Multiple whole cell patch clamp recordings were performed from one fast-spiking neuron and two or three pyramidal neurons with at least two inhibitory connections in rat insular cortical slices. The authors examined how inhibitory inputs from a presynaptic fast-spiking neuron modulate the timing of spontaneous repetitive spike firing among pyramidal neurons before and during 10 μM propofol application.
Results: Responding to activation of a fast-spiking neuron with 150-ms intervals, pyramidal cell pairs that received common inhibitory inputs from the presynaptic fast-spiking neuron showed propofol-dependent decreases in average distance from the line of identity, which evaluates the coefficient of variation in spike timing among pyramidal neurons: average distance from the line of identity just after the first activation of fast-spiking neuron was 29.2 ± 24.1 (mean ± SD, absolute value) in control and 19.7 ± 19.2 during propofol application (P < 0.001). Propofol did not change average distance from the line of identity without activating fast-spiking neurons and in pyramidal neuron pairs without common inhibitory inputs from presynaptic fast-spiking neurons. The synchronization index, which reflects the degree of spike synchronization among pyramidal neurons, was increased by propofol from 1.4 ± 0.5 to 2.3 ± 1.5 (absolute value, P = 0.004) and from 1.5 ± 0.5 to 2.2 ± 1.0 (P = 0.030) when a presynaptic fast-spiking neuron was activated at 6.7 and 10 Hz, respectively, but not at 1, 4, and 13.3 Hz.
Conclusions: These results suggest that propofol facilitates pyramidal neuron firing synchrony by enhancing inhibitory inputs from fast-spiking neurons. This synchrony of pyramidal neurons may contribute to the alpha rhythm associated with propofol-induced loss of consciousness.
翻译：易菁 编辑：佟睿 审校：曹莹
贵州医科大学 高鸿教授课题组