Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee, USA.
Department of Pharmacology and Physiology, Institute of Biomedical Engineering, University of Montreal, Montreal, Quebec, Canada.
Physiol Rep. 2023 Mar;11(5):e15633. doi: 10.14814/phy2.15633.
Vagus nerve stimulation (VNS) is used to treat drug-resistant epilepsy and depression, with additional applications under investigation. The noradrenergic center locus coeruleus (LC) is vital for VNS effects; however, the impact of varying stimulation parameters on LC activation is poorly understood. This study characterized LC activation across VNS parameters. Extracellular activity was recorded in rats' left LC while 11 VNS paradigms, utilizing variable frequencies and bursting characteristics, were pseudorandomly delivered to the left cervical vagus for five cycles. Neurons' change from baseline firing rate and timing response profiles were assessed. The proportion of neurons categorized as responders over 5 VNS cycles doubled in comparison to the first VNS cycle (p < 0.001) for all VNS paradigms, demonstrating an amplification effect. The percentage of positively consistent/positive responders increased for standard VNS paradigms with frequencies ≥10 Hz and for bursting paradigms with shorter interburst intervals and more pulses per burst. The synchrony between pairs of LC neurons increased during bursting VNS but not standard paradigms. Also, the probability of evoking a direct response during bursting VNS was higher with longer interburst intervals and a higher number of pulses per burst. Standard paradigms between 10-30 Hz best positively activates LC with consistency to VNS while the best bursting paradigm to increase activity was 300 Hz, seven pulses per burst separated by 1 s. Bursting VNS was effective in increasing synchrony between pairs of neurons, suggesting a common network recruitment originating from vagal afferents. These results indicate differential activation of LC neurons depending on the VNS parameters delivered.
迷走神经刺激(VNS)用于治疗耐药性癫痫和抑郁症,还有其他应用正在研究中。去甲肾上腺素能中心蓝斑(LC)对 VNS 效应至关重要;然而,不同刺激参数对 LC 激活的影响知之甚少。本研究描述了 VNS 参数对 LC 激活的影响。在大鼠左侧 LC 中记录细胞外活动,同时对左侧颈迷走神经施加 11 种 VNS 模式,这些模式利用不同的频率和爆发特征,以伪随机方式在五个周期内传递。评估神经元从基线放电率和时间响应谱的变化。与第一个 VNS 周期相比,所有 VNS 模式下,在五个 VNS 周期内被归类为反应者的神经元比例增加了一倍(p<0.001),表现出放大效应。具有≥10 Hz 频率的标准 VNS 模式和具有较短的爆发间隔和更多爆发脉冲的爆发模式的正一致性/正反应者百分比增加。在爆发 VNS 期间,LC 神经元对之间的同步性增加,但在标准模式下则没有。此外,在爆发 VNS 期间,具有较长爆发间隔和更多爆发脉冲的情况下,诱发直接反应的概率更高。在 10-30 Hz 之间的标准模式最能以一致性正向激活 LC,而增加活动的最佳爆发模式是 300 Hz,7 个脉冲每 1 s 爆发一次。爆发 VNS 有效地增加了神经元对之间的同步性,表明起源于迷走传入的共同网络募集。这些结果表明,LC 神经元的激活取决于传递的 VNS 参数。
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