Optogenetic Control of Targeted Peripheral Axons in Freely Moving Animals

Optogenetic control of the peripheral nervous system (PNS) would enable novel studies of motor control, somatosensory transduction, and pain processing. Such control requires the development of methods to deliver opsins and light to targeted sub-populations of neurons within peripheral nerves. We report here methods to deliver opsins and light to targeted peripheral neurons and robust optogenetic modulation of motor neuron activity in freely moving, non-transgenic mammals. We show that intramuscular injection of adeno-associated virus serotype 6 enables expression of channelrhodopsin (ChR2) in motor neurons innervating the injected muscle. Illumination of nerves containing mixed populations of axons from these targeted neurons and from neurons innervating other muscles produces ChR2-mediated optogenetic activation restricted to the injected muscle. We demonstrate that an implanted optical nerve cuff is well-tolerated, delivers light to the sciatic nerve, and optically stimulates muscle in freely moving rats. These methods can be broadly applied to study PNS disorders and lay the groundwork for future therapeutic application of optogenetics.外周神经系统（peripheral nervous system, PNS）的光遗传学控制，将为运动控制、体感转导与疼痛处理等领域带来全新研究契机。实现此类控制，需开发可将视蛋白与光线递送至外周神经内特定神经元亚群的技术方法。本研究报道了可将视蛋白与光线递送至靶向外周神经元的方案，以及可在自由活动的非转基因哺乳动物中实现运动神经元活动高效稳定光遗传学调控的方法。我们证实，通过肌内注射腺相关病毒血清型6，可使注射肌肉所支配的运动神经元表达通道视紫红质（channelrhodopsin, ChR2）。对包含上述靶向神经元轴突与其他肌肉支配神经元轴突的混合神经进行光照，可实现仅局限于注射肌肉的、由ChR2介导的光遗传学激活。我们还证实，植入式光学神经套袖具有良好的生物耐受性，可将光线递送至坐骨神经，并能在自由活动的大鼠体内实现肌肉的光学刺激。本研究开发的方法可广泛应用于外周神经系统疾病的相关研究，并为光遗传学未来的治疗应用奠定坚实基础。