Abstract：
BACKGROUND: The vagus nerve plays an important role in neuroimmune interactions and in the regulation of inflammation. A major source of efferent vagus nerve fibers that contribute to the regulation of inflammation is the brainstem dorsal motor nucleus of the vagus (DMN), as recently shown using optogenetics. In contrast to optogenetics, electrical neuromodulation has broad therapeutic implications. However, the anti-inflammatory effectiveness of electrical stimulation of the DMN (eDMNS) and the possible heart rate (HR) alterations associated with this approach have not been investigated. Here, we examined the effects of eDMNS on HR and cytokine levels in mice administered with lipopolysaccharide (LPS, endotoxin) and in mice subjected to cecal ligation and puncture (CLP) sepsis.
METHODS: Anesthetized male 8-10-week-old C57BL/6 mice on a stereotaxic frame were subjected to eDMNS using a concentric bipolar electrode inserted into the left or right DMN or sham stimulation. eDMNS (500, 250 or 50 μA at 30 Hz, for 1 min) was performed and HR recorded. In endotoxemia experiments, sham or eDMNS utilizing 250 μA or 50 μA was performed for 5 mins and was followed by LPS (0.5 mg/kg) i.p. administration. eDMNS was also applied in mice with cervical unilateral vagotomy or sham operation. In CLP experiments sham or left eDMNS was performed immediately post CLP. Cytokines and corticosterone were analyzed 90 mins after LPS administration or 24 h after CLP. CLP survival was monitored for 14 days.
RESULTS: Either left or right eDMNS at 500 μA and 250 μA decreased HR, compared with baseline pre-stimulation. This effect was not observed at 50 μA. Left side eDMNS at 50 μA, compared with sham stimulation, significantly decreased serum and splenic levels of the pro-inflammatory cytokine TNF and increased serum levels of the anti-inflammatory cytokine IL-10 during endotoxemia. The anti-inflammatory effect of eDMNS was abrogated in mice with unilateral vagotomy and was not associated with serum corticosterone alterations. Right side eDMNS in endotoxemic mice suppressed serum TNF and increased serum IL-10 levels but had no effects on splenic cytokines. In mice with CLP, left side eDMNS suppressed serum IL-6, as well as splenic IL-6 and increased splenic IL-10 and significantly improved the survival rate of CLP mice.
CONCLUSIONS: For the first time we show that a regimen of eDMNS which does not cause bradycardia alleviates LPS-induced inflammation. These eDMNS anti-inflammatory effects require an intact vagus nerve and are not associated with corticosteroid alterations. eDMNS also decreases inflammation and improves survival in a model of polymicrobial sepsis. These findings are of interest for further studies exploring bioelectronic anti-inflammatory approaches targeting the brainstem DMN.
METHODS: Anesthetized male 8-10-week-old C57BL/6 mice on a stereotaxic frame were subjected to eDMNS using a concentric bipolar electrode inserted into the left or right DMN or sham stimulation. eDMNS (500, 250 or 50 μA at 30 Hz, for 1 min) was performed and HR recorded. In endotoxemia experiments, sham or eDMNS utilizing 250 μA or 50 μA was performed for 5 mins and was followed by LPS (0.5 mg/kg) i.p. administration. eDMNS was also applied in mice with cervical unilateral vagotomy or sham operation. In CLP experiments sham or left eDMNS was performed immediately post CLP. Cytokines and corticosterone were analyzed 90 mins after LPS administration or 24 h after CLP. CLP survival was monitored for 14 days.
RESULTS: Either left or right eDMNS at 500 μA and 250 μA decreased HR, compared with baseline pre-stimulation. This effect was not observed at 50 μA. Left side eDMNS at 50 μA, compared with sham stimulation, significantly decreased serum and splenic levels of the pro-inflammatory cytokine TNF and increased serum levels of the anti-inflammatory cytokine IL-10 during endotoxemia. The anti-inflammatory effect of eDMNS was abrogated in mice with unilateral vagotomy and was not associated with serum corticosterone alterations. Right side eDMNS in endotoxemic mice suppressed serum TNF and increased serum IL-10 levels but had no effects on splenic cytokines. In mice with CLP, left side eDMNS suppressed serum IL-6, as well as splenic IL-6 and increased splenic IL-10 and significantly improved the survival rate of CLP mice.
CONCLUSIONS: For the first time we show that a regimen of eDMNS which does not cause bradycardia alleviates LPS-induced inflammation. These eDMNS anti-inflammatory effects require an intact vagus nerve and are not associated with corticosteroid alterations. eDMNS also decreases inflammation and improves survival in a model of polymicrobial sepsis. These findings are of interest for further studies exploring bioelectronic anti-inflammatory approaches targeting the brainstem DMN.
摘要：
背景：迷走神经在神经免疫相互作用和炎症调节中起重要作用。如最近使用光遗传学显示的,有助于调节炎症的传出迷走神经纤维的主要来源是迷走神经的脑干背侧运动核(DMN)。与光遗传学相反，电神经调节具有广泛的治疗意义。然而,尚未研究电刺激DMN(eDMNS)的抗炎效果以及与该方法相关的可能心率(HR)改变.这里,我们检查了eDMNS对脂多糖（LPS，内毒素）和接受盲肠结扎和穿孔（CLP）脓毒症的小鼠。
方法:使用插入左或右DMN或假刺激的同心双极电极对立体定位框架上的麻醉的雄性8-10周龄C57BL/6小鼠进行eDMNS。eDMNS（500、250或50μA，30Hz，进行1分钟）并记录HR。在内毒素血症实验中,使用250μA或50μA的sham或eDMNS进行5分钟，然后进行LPS（0.5mg/kg）腹膜内给药。eDMNS也应用于宫颈单侧迷走神经切断术或假手术的小鼠。在CLP实验中,在CLP后立即进行假的或左的eDMNS。在LPS给药后90分钟或CLP后24小时分析细胞因子和皮质酮。监测CLP存活14天。
结果：在500μA和250μA时，左或右eDMNS降低了HR，与基线预刺激相比。在50μA时没有观察到这种效果。左侧eDMNS为50μA,与假刺激相比，内毒素血症期间，促炎细胞因子TNF的血清和脾脏水平显着降低，抗炎细胞因子IL-10的血清水平升高。在单侧迷走神经切断术的小鼠中，eDMNS的抗炎作用被消除，并且与血清皮质酮的改变无关。内毒素血症小鼠的右侧eDMNS抑制血清TNF并增加血清IL-10水平，但对脾细胞因子没有影响。在患有CLP的小鼠中，左侧eDMNS抑制血清IL-6和脾脏IL-6，增加脾脏IL-10，并显着提高CLP小鼠的生存率。
结论：我们首次表明，不引起心动过缓的eDMNS方案可减轻LPS诱导的炎症。这些eDMNS抗炎作用需要完整的迷走神经，并且与皮质类固醇改变无关。eDMNS还在多微生物败血症模型中降低炎症并改善存活率。这些发现对于探索靶向脑干DMN的生物电子抗炎方法的进一步研究是有意义的。
方法:使用插入左或右DMN或假刺激的同心双极电极对立体定位框架上的麻醉的雄性8-10周龄C57BL/6小鼠进行eDMNS。eDMNS（500、250或50μA，30Hz，进行1分钟）并记录HR。在内毒素血症实验中,使用250μA或50μA的sham或eDMNS进行5分钟，然后进行LPS（0.5mg/kg）腹膜内给药。eDMNS也应用于宫颈单侧迷走神经切断术或假手术的小鼠。在CLP实验中,在CLP后立即进行假的或左的eDMNS。在LPS给药后90分钟或CLP后24小时分析细胞因子和皮质酮。监测CLP存活14天。
结果：在500μA和250μA时，左或右eDMNS降低了HR，与基线预刺激相比。在50μA时没有观察到这种效果。左侧eDMNS为50μA,与假刺激相比，内毒素血症期间，促炎细胞因子TNF的血清和脾脏水平显着降低，抗炎细胞因子IL-10的血清水平升高。在单侧迷走神经切断术的小鼠中，eDMNS的抗炎作用被消除，并且与血清皮质酮的改变无关。内毒素血症小鼠的右侧eDMNS抑制血清TNF并增加血清IL-10水平，但对脾细胞因子没有影响。在患有CLP的小鼠中，左侧eDMNS抑制血清IL-6和脾脏IL-6，增加脾脏IL-10，并显着提高CLP小鼠的生存率。
结论：我们首次表明，不引起心动过缓的eDMNS方案可减轻LPS诱导的炎症。这些eDMNS抗炎作用需要完整的迷走神经，并且与皮质类固醇改变无关。eDMNS还在多微生物败血症模型中降低炎症并改善存活率。这些发现对于探索靶向脑干DMN的生物电子抗炎方法的进一步研究是有意义的。
