In previous reports, we developed a method to apply Brownian optogenetic noise-photostimulation (BONP, 470 nm) up to 0.67 mW on the barrel cortex of in vivo ChR2 transgenic mice. In such studies, we found that the BONP produces an increase in the evoked field potentials and the neuronal responses of pyramidal neurons induced by somatosensory mechanical stimulation. Here we extended such findings by examining whether the same type of BONP augments the Na+ current amplitude elicited by voltage-clamp ramps of dissociated pyramidal neurons from the somatosensory cortex of ChR2 transgenic and wild type mice. We found that in all neurons from the ChR2 transgenic mice, but none of the wild type mice, the peak amplitude of a TTX-sensitive Na+ current and its inverse of latency exhibited inverted U-like graphs as a function of the BONP level. It means that an intermediate level of BONP increases both the peak amplitude of the Na+ current and its inverse of latency. Our research suggests that the impact of BONP on the Na+ channels of pyramidal neurons could be associated with the observed augmentation-effects in our previous in vivo preparation. Moreover, it provides caution information for the use of an appropriate range of light intensity, <0.67 mW, which could avoid opto non-genetics (also termed “optonongenetic”) related responses due to light-induced temperature changes.

中文翻译：

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噪声光增强光遗传转基因小鼠体感锥体神经元中的 Na+ 电流

在之前的报告中，我们开发了一种方法，在体内 ChR2 转基因小鼠的桶状皮层上应用布朗光遗传噪声光刺激（BONP，470 nm）高达 0.67 mW。在这些研究中，我们发现 BONP 会增加诱发场电位和由体感机械刺激诱导的锥体神经元的神经元反应。在这里，我们通过检查相同类型的 BONP 是否增加了由 ChR2 转基因和野生型小鼠的体感皮层分离的锥体神经元的电压钳斜坡引起的 Na+ 电流幅度，从而扩展了这些发现。我们发现，在 ChR2 转基因小鼠的所有神经元中，但没有野生型小鼠，TTX 敏感的 Na+ 电流的峰值幅度及其潜伏期的倒数表现出倒 U 形图，作为 BONP 水平的函数。这意味着中等水平的 BONP 会增加 Na+ 电流的峰值幅度及其潜伏期的倒数。我们的研究表明，BONP 对锥体神经元 Na+ 通道的影响可能与我们之前在体内制备中观察到的增强效应有关。此外，它还为使用适当范围的光强度提供了警告信息，<0.67 mW，这可以避免由于光引起的温度变化引起的光非遗传（也称为“光非遗传”）相关反应。