Large Scale In Vivo Recording of Sensory Neuron Activity with GCaMP6
Large Scale In Vivo Recording of Sensory Neuron Activity with GCaMP6
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DOI：
10.1523/eneuro.0417-17.2018
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发表时间：
2018-01-01
期刊：
影响因子：
3.4
通讯作者：
McMahon, Stephen B.
中科院分区：
文献类型：
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作者：
Chisholm, Kim I.;Khovanov, Nikita;McMahon, Stephen B.
对生理环境中完整细胞网络的研究越来越重视，这使得中枢神经系统（CNS）的活体成像技术取得了快速进展，而外周系统的研究仍未得到充分的探索。为了评估大型感觉神经元网络，我们在雄性和雌性C57bl/6小鼠中选择性地用GCaMP6s标记初级传入事件，并在体内观察它们对外周刺激的功能反应。我们表明，我们能够同时监测数百个感觉神经元的活动，在大多数情况下，具有足够的灵敏度来检测单个动作电位，典型的上升时间约为200毫秒，以及时间常数约为700毫秒的指数衰减。利用这项技术，我们能够描述在正常和炎症条件下，大量感觉神经元对无害和有害的机械和热刺激的反应。我们证明，大多数初级传入事件是多模态的，50-80%的热敏DRG神经元也对有害的机械刺激作出反应。我们还特别评估了一小部分外周冷神经元，并在无菌和持续炎症模型后证明了对冷却的显着敏感性，与未炎症反应相比，在降低5℃时敏感性已经显著增加。这不仅揭示了周围神经系统（病理）生理学的有趣新见解，而且还证明了这种成像技术对初级传入神经生理变化的敏感性。
Greater emphasis on the study of intact cellular networks in their physiological environment has led to rapid advances in intravital imaging of the central nervous system (CNS), while the peripheral system remains largely unexplored. To assess large networks of sensory neurons, we selectively label primary afferents with GCaMP6s in male and female C57bl/6 mice and visualize their functional responses to peripheral stimulation in vivo. We show that we are able to monitor the activity of hundreds of sensory neurons simultaneously, with sufficient sensitivity to detect, in most cases, single action potentials with a typical rise time of around 200 ms, and an exponential decay with a time constant of approximately 700 ms. With this technique we are able to characterize the responses of large populations of sensory neurons to innocuous and noxious mechanical and thermal stimuli under normal and inflammatory conditions. We demonstrate that the majority of primary afferents are polymodal with between 50-80% of thermally sensitive DRG neurons responding also to noxious mechanical stimulation. We also specifically assess the small population of peripheral cold neurons and demonstrate significant sensitization to cooling after a model of sterile and persistent inflammation, with significantly increased sensitivity already at decreases of 5 degrees C when compared to uninflamed responses. This not only reveals interesting new insights into the (patho)physiology of the peripheral nervous system but also demonstrates the sensitivity of this imaging technique to physiological changes in primary afferents.