In vivo patch clamp analysis of pain transmission in the spinal dorsal horn

在体膜片钳记录技术已发展用于分析施加于皮肤的伤害性或非伤害性刺激所诱发的突触反应。在乌拉坦麻醉大鼠的人工通气和监测血压和体温的情况下，通过椎板切除术暴露L4或L5腰髓，然后将大鼠置于立体毒性装置上。使用显微操作器，记录电极插入背角和千兆欧姆密封建立。膜片钳记录来自位于胶状质（SG，板层II）的神经元，其静息膜电位为-50 mV-75 mV，输入膜电阻为250 Ω-600 MΩ。在电压钳条件下，它们在保持电位为-70 mV时出现自发性快兴奋性突触后电流（EPSC），在0 mV时出现抑制性突触后电流（IPSC）。对同侧后肢施加捏夹和空气刺激可增加快EPSC的频率和幅度 ...更多信息 在所有测试的SG神经元中，其中一些在电流钳条件下启动肌动蛋白电位。与此相反，所有SG神经元检查，没有反应的伤害性热刺激。为了了解有害的热信息传递到哪里，从更深的神经元进行了膜片钳记录。背角神经元对伤害性热刺激的反应表现为快速EPSCs的频率和幅度增加。然而，这些反应仅由神经元能快速EPSC介导，并且在所有测试的神经元中均未检测到慢反应，而慢反应应该由肽介导。这些观察结果表明，SG神经元接受伤害性和非伤害性机械，但不是有害的热输入。Aδ和C初级传入纤维可能通过激活非NMDA受体传递力学信息。而有害的热信息则通过激活海马神经元感受器传递到更深层。肽能传递的机制需要澄清。少

In vivo patch-clamp recording technique has been developed to analyze synaptic responses evoked by noxious or non-noxious stimuli applied to the skin. Under artificial ventilation of rats anesthetized with urethane and monitoring the blood pressure and temperature, L4 or L5 lumbar spinal cord was exposed by laminectomy and then the rat was placed on a stereotoxic apparatus. Using a micromanipulator, recording electrodes were inserted into the dorsal horn and giga-ohm sealing was established. Patch-clamp recordings were obtained from neurons located in substantia gelatinosa (SG, lamina II), which had a resting membrane potential of -50〜-75 mV and an input membrane resistance of 250〜600 MΩ. Under a voltage-clamp condition, they exhibited spontaneous fast excitatory postsynaptic currents (EPSCs) at holding potential of -70 mV and inhibitory postsynaptic currents (IPSCs) at 0 mV. Pinch and air stimuli applied to the ipsilateral hind limb increased the fast EPSCs in frequency and amplitude … More in all SG neurons tested, some of which initiated an actin potential under a current clamp condition. In contrast, all SG neurons examined, did not respond to noxious heat stimuli. To know where the noxious heat information is transmitted, patch-clamp recordings were made from deeper neurons. The deep dorsal horn neurons responded to noxious heat stimuli with increasing fast EPSCs in frequency and amplitude. The responses were, however, mediated solely by glutamatergic fast EPSCs, and no slow responses, supposed to be mediated by peptides, were detected in all neurons tested. These observations suggest that SG neurons receive nociceptive and non-nociceptive mechanical, but not noxious thermal inputs. The mechanical information may be transmitted by Aδ and C primary afferent fibers through an activation of non-NMDA receptor. Whereas, the noxious heat information is transmitted to the deeper laminae through activating glutamatergic receptors. Mechanisms of peptidergic transmission are required to be clarified. Less