patch-clamp recording to study the electrical responses of motor neurons to spinal cord stimulation

了解运动神经元对脊髓刺激的反应

Spinal cord stimulation (SCS) can effectively restore locomotor function after spinal cord injury (SCI). Andreas Rowald et al. reported that SCS enables lower limb locomotor and trunk function within a single day1. Exploring the biological mechanism of SCS for locomotor recovery is a critical and trending research field for developing a more precise SCS strategy. For example, Gr&#233;goire Courtine&#39;s team demonstrated that excitatory Vsx2 interneuron and Hoxa10 neurons in the spinal cord are the key neurons to response to SCS, and cell-specific neuromodulation is feasible to restore the rat walking ability after SCI2. However, few studies focus on the electrical mechanism of SCS at a single-cell scale. Although it is well-known that the suprathreshold direct current stimulus can elicit the action potentials (APs) in the classic squid experiment3,4,5, how the pulsed alternating electrical stimulation, such as SCS, affects the motor signal generation is still unclear.
Given the complexity of intraspinal neural circuits, appropriate selection for cell population is important for investigating the electrical mechanism of SCS. Although SCS restores motor function by activating the proprioceptive pathway6, the motor neurons are the final unit to execute the motor command, derived from integrating proprioception information afferent input7. Therefore, directly studying the electrical characteristics of motor neurons with SCS can help us understand the underlying logic of spinal motor modulation.
As we know, patch-clamp is the golden-standard method for cellularly electrophysiological recording with extremely high spatiotemporal resolution8. Therefore, this study describes a method using a patch clamp to study the electrical responses of motor neurons to SCS. Compared with the brain patch-clamp9, the spinal cord patch-clamp is more difficult due to the following reasons: (1) The spinal cord is protected by the vertebral canal with tiny volume, which requires very fine micromanipulation and rigorous ice-cold maintenance to obtain better cell viability. (2) Because the spinal cord is too slender to be secured on the cutting tray, it should be immersed in low-melting point agarose and trimmed after solidification.
Hence, this method provides technical details in dissecting the spinal cord and maintaining the cell viability at the same time so as to smoothly study the electrical mechanism of SCS on motor neurons and avoid unnecessary trials and mistakes.

作者聚焦：推进脊髓刺激 - 通过膜片钳电生理学探索运动神经元的细胞反应 

脊髓切片 的离体 制备，用于脊髓刺激过程中运动神经元的全细胞膜片钳记录

Spinal cord stimulation can help patients resolve most motion functions after injury. Most neurons are to execute sensory mode behaviors. Studying the electric response of most neurons can aid in understanding the underlying logic of spinal load neuromodulation.A patch clamp is the golden standard method for cellular electrophysiological recordings with the extremely high spatial temporal resolution. Therefore, this study describes a method using a patch clamp to simultaneously record the aortas stimulus characteristics and cellular responses of motor neurons at a single-cell scale. Compared with the brain patch clamp, the spinal cord patch clamp is more difficult, because the spinal cord is well protected by the vertebral canal with tiny volume.Therefore, this protocol provides technical details in quickly micro dissecting the spinal cord and reverse maintenance to obtain better cell viability. Patch clamp allows a unique understanding of the synaptic transmissions and the understanding of action potentials, coding pattern activities by the spinal cord stimulation.

Watch this Scientific Journal Video about Patch-Clamp Recording to Study the Electrical Responses of Motor Neurons to Spinal Cord Stimulation at JoVE.com

Patch-Clamp Recording to Study the Electrical Responses of Motor Neurons to Spinal Cord Stimulation  

膜片钳记录，用于研究运动神经元对脊髓刺激的电反应

首先，将准备好的脊髓切片放入记录室。然后将显微操作系统的阳极放置在阴极背中线附近，靠近背根进入区，以便正确定位脊髓刺激器。现在切换到 60 倍物镜，以识别具有光滑明亮表面而没有可见细胞核的健康神经元。稍微降低红外强度，打开荧光光源，将滤光片调整为宽带紫外激发选项。现在，选择一个合适的氟金正运动神经元，并逐渐降低电极，直到它靠近神经元。当移液器接触其表面时，在吸头水平处寻找一个小的膜压痕，并释放先前施加的正压。然后使用注射器对移液器施加负压，并等待软件界面上的电阻值上升到千兆欧。将膜电位夹在负 70 毫伏。按下放大器软件界面上的快速电容补偿按钮，然后施加短暂的负压使细胞膜破裂，然后按下放大器软件界面上的慢速电容补偿按钮。施加脊髓刺激一到两秒钟，将振幅保持在 1 到 10 毫安之间。通过逐渐增加刺激幅度来确定运动阈值，直到观察到第一个动作电位。在电流钳位模式下，使用流变基周围的五秒去极化电流注入来区分延迟和立即放电的运动神经元。关闭脊髓刺激后，继续记录膜电位以捕获自发动作电位放电。当脊髓刺激的振幅升高时，膜电位增加，并且每 10 至 20 个脉冲触发一次动作电位。脊髓刺激关闭后，神经元在短时间内发射一系列自发动作电位。然后，静息膜电位恢复到负 65 毫伏。

patch-clamp-recording-to-study-electrical-responses-motor-neurons-to

Research

JoVE Journal

Neuroscience

Patch-Clamp Recording to Study the Electrical Responses of Motor Neurons to Spinal Cord Stimulation

225 次观看.  Tsinghua University. 首先，将准备好的脊髓切片放入记录室。然后将显微操作系统的阳极放置在阴极背中线附近，靠近背根进入区，以便正确定位脊髓刺激器。现在切换到 60 倍物镜，以识别具有光滑明亮表面而没有可见细胞核的健康神经元。稍微降低红外强度，打开荧光光源，将滤光片调整为宽带紫外激发选项。现在，选择一个合适的氟金正运动神经元，并逐渐降低电极，直到它靠近神经...

视频: Patch-Clamp Recording to Study the Electrical Responses of Motor Neurons to Spinal Cord Stimulation  

The Ex vivo Preparation of Spinal Cord Slice for the Whole-Cell Patch-Clamp Recording in Motor Neurons During Spinal Cord Stimulation

Spinal cord stimulation (SCS) can effectively restore locomotor function after spinal cord injury (SCI). Because the motor neurons are the final unit to execute sensorimotor behaviors, directly studying the electrical responses of motor neurons with SCS can help us understand the underlying logic of spinal motor modulation. To simultaneously record diverse stimulus characteristics and cellular responses, a patch-clamp is a good method to study the electrophysiological characteristics at a single-cell scale. However, there are still some complex difficulties in achieving this goal, including maintaining cell viability, quickly separating the spinal cord from the bony structure, and using the SCS to successfully induce action potentials. Here, we present a detailed protocol using patch-clamp to study the electrical responses of motor neurons to SCS with high spatiotemporal resolution, which can help researcher improve their skills in separating the spinal cord and maintaining the cell viability at the same time to smoothly study the electrical mechanism of SCS on motor neuron and avoid unnecessary trial and mistake.

This protocol describes a method using a patch-clamp to study the electrical responses of motor neurons to spinal cord stimulation (SCS) with high spatiotemporal resolution, which can help researchers improve their skills in separating the spinal cord and maintaining cell viability simultaneously.

Spinal cord stimulation (SCS) can effectively restore locomotor function after spinal cord injury (SCI). Because the motor neurons are the final unit to ...

科研

神经科学

Spinal Cord Dissection for the Whole-Cell Patch-Clamp Recording in Motor Neurons

After exposing the heart of an anesthetized rat, cut the right atrium using fine scissors and inject 100 milliliters of chilled perfusing fluid at approximately two milliliters per second within one minute. Position the rat in the prone position. Cut the spine at the anterior superior iliac spine and the curvature shifting point of the thoracic column.Immediately place the isolated spine into the oxygenated ice cold perfusing solution to wash off residual blood and fat tissue. Then transfer the isolated spine to the anatomical tray with its dorsal side up and the rostral end near the operator. Fill the tray with 50 milliliters of continuously oxygenated ice cold cutting solution.Under a dissection microscope, cut the vertebral pedicles on both sides from the rostral end using micro scissors. Next, delicately sever the dura mater along its dorsal midline with micro scissors. Lift the rostral part of the spinal cord carefully and cut the nerve root, leaving about one millimeter reserved.After the spinal cord has been separated from the vertebral canal, secure it with the ventral side facing up using two insect pins. Trim any excessive nerve roots, leaving about one millimeter intact. Then separate the lumbar enlargement to a length of six to seven millimeters using a micro scissor.

脊髓解剖用于运动神经元中全细胞膜片钳记录

Preparation of Spinal Cord Slice for the Whole-Cell Patch-Clamp Recording in Motor Neurons

After dissecting the spinal cord and separating the lumbar enlargement, place the lumbar enlargement on a 35 degree slope with the dorsal side up and the caudal side down. Absorb any excess water on the tissue surface using an absorbent filter paper. Carefully pour the molten agarose gel into the Petri dish containing the lumbar enlargement.Position the Petri dish in the ice water mixture to ensure rapid gel cooling. Shape the gel into a cube of 15 by 10 by 10 millimeters, and mount it onto the specimen disc using super glue. Adjust the vibratome settings to a thickness of 350 micrometers, a speed of 0.14 to 0.16 millimeters per second, an amplitude of one millimeter, and a vibration frequency of 85 hertz.Now, use the cover slide tweezers to clip a slice and place it into the incubation chamber, filled with continuously oxygenated artificial cerebrospinal fluid.

用于运动神经元全细胞膜片钳记录的脊髓切片的制备

To begin, place the prepared spinal cord slice in the recording chamber. Then place the anode of the micro-manipulation system near the dorsal midline in the cathode close to the dorsal root entry zone for proper spinal cord stimulator positioning. Now switch to a 60X objective lens to identify a healthy neuron having a smooth and bright surface without visible nuclei.Slightly decrease the infrared intensity, turn on the fluorescent light source, and adjust the light filter to the wideband ultraviolet excitation option. Now, select an appropriate Fluoro-Gold-positive motor neuron and gradually lower the electrode until it is near the neuron. As the pipette contacts its surface, look for a small membrane indentation at the tip level and release the previously-applied positive pressure.Then apply negative pressure to the pipette using a syringe and wait until the resistance value rises to gigaohms on the software interface. Clamp the membrane potential at minus 70 millivolts. Press the fast capacitance compensation button on the amplifier's software interface, then apply a brief negative pressure to rupture the cell membrane and press the slow capacitance compensation button on the amplifier's software interface.Apply the spinal cord stimulation for one to two seconds keeping the amplitude between one and 10 milliamperes. Determine the motor threshold by gradually increasing the stimulation amplitude until the first action potential is observed. Distinguish delayed and immediate firing motor neurons using a five-second depolarizing current injection around rheobase in the current clamp mode.After turning off the spinal cord stimulation, continue recording the membrane potentials to capture the spontaneous action potentials firing. When the amplitude of spinal cord stimulation was raised, the membrane potential was increased, and the action potentials were triggered every 10 to 20 pulses. After the spinal cord stimulation was turned off, the neuron fired a series of spontaneous action potentials for a short period of time.Then, the resting membrane potential returned to minus 65 millivolts.