Wong Fong Sang I Emeline, Schroer Jonas, Halbhuber Lisa, Warm Davide, Yang Jenq-Wei, Luhmann Heiko J, Kilb Werner, Sinning Anne
Institute of Physiology, University Medical Center Mainz, Johannes Gutenberg University, Duesbergweg 6, 55128 Mainz, Germany.
Int J Mol Sci. 2021 Jun 19;22(12):6575. doi: 10.3390/ijms22126575.
A substantial proportion of neurons undergoes programmed cell death (apoptosis) during early development. This process is attenuated by increased levels of neuronal activity and enhanced by suppression of activity. To uncover whether the mere level of activity or also the temporal structure of electrical activity affects neuronal death rates, we optogenetically controlled spontaneous activity of synaptically-isolated neurons in developing cortical cultures. Our results demonstrate that action potential firing of primary cortical neurons promotes neuronal survival throughout development. Chronic patterned optogenetic stimulation allowed to effectively modulate the firing pattern of single neurons in the absence of synaptic inputs while maintaining stable overall activity levels. Replacing the burst firing pattern with a non-physiological, single pulse pattern significantly increased cell death rates as compared to physiological burst stimulation. Furthermore, physiological burst stimulation led to an elevated peak in intracellular calcium and an increase in the expression level of classical activity-dependent targets but also decreased Bax/BCL-2 expression ratio and reduced caspase 3/7 activity. In summary, these results demonstrate at the single-cell level that the temporal pattern of action potentials is critical for neuronal survival versus cell death fate during cortical development, besides the pro-survival effect of action potential firing per se.
在早期发育过程中，相当一部分神经元会经历程序性细胞死亡（凋亡）。这一过程会因神经元活动水平的增加而减弱，因活动的抑制而增强。为了揭示仅仅是活动水平还是电活动的时间结构也会影响神经元死亡率，我们在发育中的皮质培养物中通过光遗传学方法控制突触隔离神经元的自发活动。我们的结果表明，初级皮质神经元的动作电位发放促进了整个发育过程中的神经元存活。慢性模式化光遗传学刺激能够在没有突触输入的情况下有效调节单个神经元的发放模式，同时保持稳定的整体活动水平。与生理性爆发刺激相比，用非生理性的单脉冲模式取代爆发发放模式显著提高了细胞死亡率。此外，生理性爆发刺激导致细胞内钙峰值升高，经典的活动依赖性靶点表达水平增加，但也降低了Bax/BCL-2表达比率并降低了caspase 3/7活性。总之，这些结果在单细胞水平上表明，除了动作电位发放本身的促存活作用外，动作电位的时间模式对于皮质发育过程中神经元存活与细胞死亡的命运至关重要。
