Transcutaneous vagus nerve stimulation in cerebral ischemia

描述(申请人提供)：本提案的目标是研究经皮迷走神经刺激(TVNS)在急性脑缺血中的治疗潜力。电刺激颈部迷走神经传入纤维可以激活脑干迷走神经中枢，诱导抗兴奋性毒性和抗炎机制，增加脑血流量(CBF)。使用外科植入电极(CVN)刺激颈迷走神经是FDA批准的治疗某些癫痫和抑郁症患者的方法。最近的研究表明，CVNS对缺血性卒中动物模型的组织损伤和运动功能丧失也具有显著的保护作用。当在缺血后2.5小时启动CVN时，在各种局灶性脑缺血的大鼠模型和合并疾病的动物中，CVN可以将梗塞体积减少约50%。保护机制尚不清楚，但初步研究结果表明，它不依赖于CBF。尽管缺血研究的结果相当令人鼓舞，但由于刺激的侵袭性，CVN不适用于人类的急性中风病例。在这一应用中，我们提出了两种不同的TVNS方法来规避手术干预的问题：(1)使用最近可用的技术通过完整的皮肤刺激颈迷走神经；(2)使用针电极刺激迷走神经的耳支，该耳支为外耳提供皮肤刀。颈部TVNS和耳部TVNS已分别安全和成功地用于呃逆和疼痛患者。我们的具体目标是：(1)确定tVNS技术对局灶性脑缺血的疗效，(2)描述tVNS治疗的最佳时间窗，(3)研究tVNS和tPA联合应用是否安全有效。我们将确定颈部TVNS和耳部TVNS对梗塞范围(通过生命染色评估)和运动功能(通过行为测试和握力测量评估)的影响。为了确定它们的安全性，我们将在治疗期间监测生理参数(如动脉血压、心率、心率变异性和呼吸频率)，并在刺激后立即对动物进行跟踪，直到治疗后1周。在另外一组动物中，为了验证脑干迷走神经中心的激活，我们将进行c TVNS后FOS免疫组织化学染色。在确定了颈部TVNS和EAR TVNS的安全性和有效性后，我们将继续研究最安全和最有效的TVNS。为了确定缺血后TVNS的时间窗，我们在缺血后3h或更长时间启动TVNS，并确定其对梗塞面积的影响。我们还建议确定tPA和tVNS之间的相互作用。我们将研究tPA-tVNS联合给药对出血风险的影响。我们还将利用多模式磁共振成像和分子血栓成像来研究tVNS对tPA时间窗和疗效的影响。拟议的研究将为tVNS改善中风预后提供原理上的证据。如果成功，这些探索性研究的结果将用于不久的将来旨在优化 TVNS治疗人类急性缺血性卒中。 公共卫生相关性：本提案旨在研究经皮神经刺激治疗急性卒中的潜力。具体地说，我们建议在卒中大鼠模型中确定经皮迷走神经刺激(TVNS)的安全性和有效性，并利用最先进的磁共振技术，建立TVNS与组织纤溶酶原激活剂的相互作用，这是FDA批准的唯一急性卒中治疗方法。总体而言，这项研究有助于开发一种实用的治疗急性中风的新方法。

DESCRIPTION (provided by applicant): The goal of this proposal is to investigate the therapeutic potential of transcutaneous vagus nerve stimulation (tVNS) in acute cerebral ischemia. Electrical stimulation of the afferent vagal fibers in the neck has been shown to activate the brainstem vagal centers, induce anti-excitotoxic and anti-inflammatory mechanisms, and increase cerebral blood flow (CBF). Stimulation of the cervical vagus nerve using surgically implanted electrodes (cVNS) is an FDA-approved treatment in some epilepsy and depression patients. Recent studies demonstrated that cVNS provides substantial protection against tissue injury and motor function loss in animal models of ischemic stroke as well. cVNS, when initiated up to 2.5 hours after ischemia, reduces infarct volume by approximately 50% in a variety of rat models of focal cerebral ischemia and in animals with comorbid conditions. The mechanism of protection is not clear yet, but initial findings suggest that it is CBF independent. Even though the findings of ischemia studies are quite encouraging, cVNS is not applicable to acute stroke cases in humans due to invasive nature of the stimulation. In this application, we propose two different tVNS approaches to circumvent the problem of surgical intervention: (1) to stimulate the cervical vagus nerve through the intact skin using a recently available technology and (2) to stimulate the auricular branch of the vagus nerve that supplies a dermatome in external ear using needle electrodes. Both cervical and auricular tVNS have been safely and successfully used in patients with hiccups and pain, respectively. Our specific aims are: (1) determine the efficacy of tVNS techniques in focal ischemia, (2) describe the optimal time window of tVNS treatment, (3) study whether concomitant application of tVNS and tPA is safe and effective in cerebral ischemia. We will determine the effects of cervical tVNS and ear tVNS on infarct size (as assessed by vital stain) and motor function (as assessed by behavioral tests and grip strength measurements). To determine their safety, we will monitor physiological parameters (e.g., arterial blood pressure, heart rate, heart rate variability, and respiration rate) during an immediately after stimulation and will follow-up animals up to 1 week after the treatment. In an additional group of animals, to verify the activation of brainstem vagal centers, we will perform c Fos immunohistochemistry after tVNS. After determining the safety and efficacy of neck tVNS and ear tVNS in specific aim 1, we will continue our studies with the safest and most efficacious tVNS. To determine the time window of tVNS after ischemia, we initiate tVNS 3 hours or more after ischemia and determine its effect on infarct size. We also propose to determine the interaction between tPA and tVNS. We will examine the effect of tPA - tVNS co-administration on risk of hemorrhage. We also will investigate the effect of tVNS on tPA's time window and efficacy using multi-modal MR imaging with molecular thrombus imaging. The proposed studies will provide the proof of principle that tVNS improves stroke outcome. If successful, the findings of these exploratory studies will be used in near future translational studies designed to optimize tVNS treatment for acute ischemic stroke in humans. PUBLIC HEALTH RELEVANCE: This proposal aims to investigate the therapeutic potential of transcutaneous nerve stimulation in acute stroke. Specifically, we propose to determine safety and efficacy of transcutaneous vagus nerve stimulation (tVNS) in rat models of stroke and using state of the art MR technology, we propose to establish the interaction of tVNS with tissue plasminogen activator, the only FDA-approved acute stroke treatment. Overall, this research could facilitate development of a practical novel treatment for acute stroke.