Losgott Thomas, Schicker Klaus W, Hilber Karlheinz, Boehm Stefan, Salzer Isabella
Division of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria.
Front Pharmacol. 2025 Apr 22;16:1561905. doi: 10.3389/fphar.2025.1561905. eCollection 2025.
Peripheral nerve endings of dorsal root ganglion (DRG) neurons act as nociceptors and generate action potentials in response to noxious stimuli. Primary cultures of dissociated DRG have been used extensively to study changes neuronal excitability caused by either analgesics or pathological conditions, such as inflammation. The dissociation procedure can be viewed as a form of axotomy, and one might expect a resulting increase in excitability of the neurons during the subsequent culture period. However, changes in firing properties of DRG neurons over time have not been investigated systematically.
Thus, the current experiments compared action potential firing in dissociated DRG neurons after one to 7 days in culture and examined Gaussian white noise as novel stimulation paradigm. Primary cultures of DRG neurons were recorded in perforated patch current-clamp. Action potentials were evoked either by a sequence of five rectangular current pulses with increasing amplitudes or by Gaussian white noise of varying RMS amplitudes and frequencies.
Conventional rectangular current injections triggered 19 20 action potentials in cells when recorded within 24 h after dissociation. After 7 days in culture, DRG neurons fired 4.3 0.7 action potentials in response to current pulses. Inflammatory mediators increased numbers of action potentials evoked by rectangular current pulses within 24 h after dissociation to 66 54, but left those elicited after 7 days unaltered (4.3 0.5). In the same set of neurons kept in culture for 7 days, Gaussian white noise stimuli triggered 1,540 470 action potentials, and this number was increased to 2089 685 by inflammatory mediators. The Kv7 channel activator retigabine and the paracetamol metabolite n-acetyl-p-benzoquinone imine (NAPQI) decreased numbers of action potentials triggered by Gaussian white noise, but failed to do so when rectangular current pulses were used as stimuli, both in neurons after 7 days in culture.
These results demonstrate a decrease in the excitability of DRG neurons from day one to 7 after dissociation and reveal Gaussian white noise as reliable trigger of action potential firing in these neurons.
背根神经节（DRG）神经元的外周神经末梢作为伤害感受器，在受到有害刺激时产生动作电位。解离DRG的原代培养物已被广泛用于研究镇痛药或病理状况（如炎症）引起的神经元兴奋性变化。解离过程可被视为一种轴突切断形式，人们可能预期在随后的培养期内神经元兴奋性会增加。然而，DRG神经元放电特性随时间的变化尚未得到系统研究。
因此，当前实验比较了培养1至7天后解离的DRG神经元的动作电位发放情况，并将高斯白噪声作为一种新的刺激范式进行研究。在穿孔膜片钳电流钳模式下记录DRG神经元的原代培养物。动作电位由一系列五个幅度递增的矩形电流脉冲或不同均方根幅度和频率的高斯白噪声诱发。
在解离后24小时内记录时，传统的矩形电流注入在细胞中触发19至20个动作电位。培养7天后，DRG神经元对电流脉冲发放4.3至0.7个动作电位。炎症介质在解离后24小时内将矩形电流脉冲诱发的动作电位数量增加至66至54个，但7天后诱发的动作电位数量未改变（4.3至0.5个）。在同一组培养7天的神经元中，高斯白噪声刺激触发1540至470个动作电位，炎症介质将此数量增加至2089至685个。Kv7通道激活剂瑞替加滨和对乙酰氨基酚代谢产物N-乙酰对苯醌亚胺（NAPQI）减少了高斯白噪声触发的动作电位数量，但在培养7天后的神经元中，当使用矩形电流脉冲作为刺激时则未能减少动作电位数量。
这些结果表明，解离后第1天至第7天DRG神经元的兴奋性降低，并揭示高斯白噪声是这些神经元动作电位发放的可靠触发因素。
