The mechanisms of N2O block of T-type Ca2+ channels in the pain pathway

N2O 阻断疼痛通路中 T 型 Ca2 通道的机制

• 批准号: 7393919
• 负责人: PEIHAN ORESTES
• 金额: $ 4.1万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-12-01 至 2010-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7393919
• 关键词: Absence of pain sensation; Accounting; Adrenergic Agents; Affect; Afferent Neurons; Analgesics; Anesthesia and Analgesia; Anesthetics; Animals; Behavioral; Binding; Calcium Channel; Chelating Agents; Chemicals; Chromosome Pairing; Class; Clinical; Coculture Techniques; Copper; Data; Effectiveness; Elevation; Exposure to; Fire - disasters; Free Radicals; Gated Ion Channel; General anesthetic drugs; Generations; Glutamates; Hippocampus (Brain); Histidine; Investigation; Ion Channel; Knockout Mice; Knowledge; Ligands; Light; Link; Mechanics; Mediating; Membrane; Membrane Potentials; Metals; Molecular; Mus; N-Methyl-D-Aspartate Receptors; Neurons; Nitrous Oxide; Pacemakers; Pain; Pathology; Pathway interactions; Perception; Peripheral; Peripheral Nervous System; Play; Posterior Horn Cells; Predisposition; Process; Property; Protein Isoforms; Proteins; Rattus; Recombinants; Reporting; Role; Seizures; Signal Transduction; Site; Sleep; Spinal Ganglia; Synapses; Synaptic Transmission; T-Type Calcium Channels; Testing; Thinking; Trace metal; Wakefulness; Zinc; adrenergic; base; cellular targeting; central sensitization; chronic neuropathic pain; clinically relevant; dorsal horn; endogenous opioids; extracellular; free radical oxygen; interest; knock-down; research study; voltage

DESCRIPTION (provided by applicant): Nitrous oxide has been used as a powerful analgesic for centuries, but little is known of its cellular mechanism of action. This proposal outlines our plans to explore the mechanism of nitrous oxide's effect on ion channels, which has not yet been described. Nitrous oxide (N2O) is of particular interest because it is one of the few agents that are selective for the CaV3.2 isoform of T-type calcium channels. Interestingly, this particular channel has been recently implicated in the pain pathway (Choi et al., 2006). Thus, we hope to describe the mechanism of N2O's effect on T-channels and at the synapse. We also plan to explain the relationships between N2O, the pain pathway, and T-type via behavioral studies of CaV3.2-null mice. Pharmacological and electrophysiological studies in dorsal root ganglion neurons are planned to continue our preliminary studies of N2O's mechanism of action. Previous studies and our recent data suggest that N2O block of CaV3.2 channels is dependent on the presence of trace metals, one extracellular histidine that is capable of binding metals, and free oxygen radicals that have the ability to modify metals and proteins. Based on this information, we plan to further explore the details of these interactions. Secondly, we propose an investigation into the effects of N2O on synaptic transmission in dorsal root ganglia-dorsal horn (DRG-DH) co-cultures. This first synapse in the pain pathway has been shown to be the site of central sensitization and the target of some general anesthetics. N2O inhibits currents through NMDA receptors and T-channels, which are both present at this synapse. Thus we hypothesize that N2O may exert some of its analgesic effects here. Lastly, the proposed behavioral pain testing on CaV3.2 knockout mice after exposure to N2O will shed light on the role of T-type channels in mediating N20 analgesia. We plan to test multiple types of pain, including chemical, mechanical, and thermal pain for a comprehensive study. If CaV3.2 channels mediate a portion of N2O analgesia, we expect that these knockout mice will display decreased sensitivity to the analgesic effects of N2O. This proposal aims to describe the unexplained molecular mechanism of a commonly used clinical analgesic, N2O. We also plan to explore N20's action on calcium channels that have already been strongly implicated in the modulation of pain. Greater knowledge of the role that these channels play in pain processing and N2O-induced analgesia will advance the treatment of chronic and neuropathic pain, and provide a better understanding of currently used anesthetics.

描述（由申请人提供）：几个世纪以来，一氧化二氮已被用作强大的镇痛药，但对其细胞作用机理知之甚少。该提议概述了我们探讨一氧化二氮对离子通道影响的机制的计划，尚未描述。一氧化二氮（N2O）特别有趣，因为它是对T型钙通道的CAV3.2同工型选择性的少数药物之一。有趣的是，该特定通道最近与疼痛途径有关（Choi等，2006）。因此，我们希望描述N2O对T通道和突触的影响的机制。我们还计划通过CAV3.2-NULL小鼠的行为研究来解释N2O，疼痛途径和T型之间的关系。计划在背根神经节神经元中的药理学和电生理研究继续我们对N2O作用机理的初步研究。先前的研究和我们最近的数据表明，Cav3.2通道的N2O块取决于痕量金属的存在，一种能够结合金属的细胞外组氨酸以及具有修改金属和蛋白质能力的游离氧自由基。基于这些信息，我们计划进一步探讨这些相互作用的细节。其次，我们提出了对N2O对背根神经节角（DRG-DH）共培养中突触传播的影响的研究。疼痛途径中的第一次突触已被证明是中央敏化的部位，也是某些一般麻醉药的目标。 N2O通过NMDA受体和T通道抑制电流，它们都存在于该突触中。因此，我们假设N2O可能在这里发挥其一些镇痛作用。最后，暴露于N2O后对CAV3.2敲除小鼠进行的行为疼痛测试将阐明T型通道在介导N20镇痛中的作用。我们计划测试多种类型的疼痛，包括化学，机械和热疼痛，以进行全面研究。如果CAV3.2通道介导了N2O镇痛的一部分，我们希望这些敲除小鼠对N2O的镇痛作用的敏感性降低。该建议旨在描述常用临床镇痛药N2O的无法解释的分子机制。我们还计划探索N20对已经与疼痛调节有关的钙通道的作用。对这些渠道在疼痛处理和N2O引起的镇痛中的作用的知识更大，将推动对慢性和神经性疼痛的治疗，并更好地了解当前使用的麻醉药。