Effects of anesthetics on thalamic excitability

麻醉药对丘脑兴奋性的影响

• 批准号: 9764914
• 负责人: Slobodan M. Todorovic
• 金额: $ 33.04万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-01-01 至 2023-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9764914
• 关键词: Acute; Adjuvant; Anesthesia procedures; Anesthetics; Animal Model; Animals; Arousal; Binding Sites; Biophysics; Brain; Calcium; Calcium Channel; Categories; Cell Nucleus; Cells; Central Medial Thalamic Nucleus; Child; Clinical; Clinical Research; Cognitive deficits; Data; Development; Drug Targeting; Exposure to; General Anesthesia; General anesthetic drugs; Genetic; Goals; Grant; Human; Hypnosis; In Vitro; Isoflurane; Ketamine; Laboratory Finding; Learning Disabilities; Life; Ligands; Medical; Molecular; Mus; N-Methyl-D-Aspartate Receptors; N-Methylaspartate; Nerve Degeneration; Neurons; Operative Surgical Procedures; Pathologic; Pharmacology; Property; Propofol; Protein Isoforms; Rattus; Recombinants; Research; Risk; Rodent; Role; Sedation procedure; Sensory; Sleep; Slice; T-Type Calcium Channels; Testing; Thalamic Nuclei; Thalamic structure; Unconscious State; Work; channel blockers; clinical effect; clinical practice; clinically relevant; density; gamma-Aminobutyric Acid; hypnotic; in vivo; inhibitor/antagonist; innovation; knock-down; neuronal excitability; neurotoxic; neurotoxicity; nonhuman primate; novel; novel strategies; patch clamp; patient population; pup; receptor; sevoflurane; voltage

Project Summary The thalamus is the major gateway for the flow of sensory information from the periphery to the cortex and the disruption of thalamocortical connectivity may be an essential common feature of the hypnotic effects of many general anesthetic (GAs). Furthermore, recent studies have identified important roles of the central medial nucleus (CeM) and ventrobasal (VB) nucleus of the thalamus in control of arousal and natural sleep. Although the role of thalamic T-type calcium channels (T-channels) in natural sleep is reasonably well established, the role of these channels in anesthesia remains poorly understood. In addition, in the past cycle of this grant we established that exposure of rat pups to clinically-relevant GAs causes increased T- current densities in the reticular thalamic nucleus (nRT), which in turn contributes to lasting hyperexcitabil- ity and pathological oscillations in thalamocortical networks in vitro and in vivo. These changes in neuronal function were reversed by selective antagonism of T-channels. We postulate that the use of pharmacological inhibitors that target T-channels may facilitate GA-induced loss of consciousness and hence may reduce usage of potent volatile GAs needed for surgery. The overall objective of this application, is to test the central hypothesis that the CaV3.1 isoform of T-channels in the CeM and VB thalamic nuclei is important for anesthetic-induced hypnosis. To test this hypothesis, we will use in vitro patch-clamp recordings from acute brain slices and recombinant cells in vitro and electroencephalographic (EEG) recordings in vivo from the CeM and VB nuclei, selective pharmacological T-channel inhibitors, and mouse genetics with global and region-specific silencing of CaV3.1 channels in the thalamus to pursue the following specific aims: Aim 1: To determine the biophysical and molecular mechanism of recombinant and native CaV3.1 channel inhibition in vitro by two common GAs, isoflurane (ISO) and sevoflurane (SEVO), and their effect on neu- ronal excitability of CeM. We will also use new approach with photoaffinity ligands of ISO (AZI-ISO) and SEVO (AZI-SEVO) to identify specific molecular binding sites on CaV3.1 channels for volatile GAs. Aim 2: To determine whether CaV3.1 channels in the CeM contribute to the alterations in thalamocortical network function during sedation/hypnosis with volatile GAs and administration of the selective T-channel inhibitor TTA-P2, as assessed by in vivo EEG recordings. Aim 3: To determine if region-specific silencing of CaV3.1 channels in the CeM and VB thalamus will have differential effects on sedation/hypnosis and thalamocortical oscillations in vivo induced by ISO and SEVO. The proposed work is innovative in that new mechanisms of anesthetic-induced loss of consciousness will be characterized. It is medically significant because it describes the importance of drugs that target voltage- gated calcium channels for potential development of safer practices in clinical anesthesia.

项目摘要 丘脑是从外围到皮质和的感官信息流动的主要门户 丘脑皮层连通性的破坏可能是催眠作用的重要特征 许多全身麻醉（气）。此外，最近的研究确定了中央的重要作用 丘脑的内侧核（CEM）和腹膜（Vb）核控制着唤醒和自然睡眠。 尽管丘脑T型钙通道（T通道）在自然睡眠中的作用相当好 建立的这些渠道在麻醉中的作用仍然很少了解。另外，过去 这笔赠款的循环我们确定，大鼠幼崽暴露于临床相关的气体会导致T- 网状丘脑核（NRT）中的当前密度，进而有助于持久的过度降低 体外和体内丘脑皮质网络中的病理振荡。这些神经元的变化 T通道的选择性拮抗作用逆转了功能。 我们假设使用靶向T通道的药理学抑制剂可能会促进GA诱导的损失 意识和因此可能会减少手术所需的有效挥发性气体的使用。总体 该应用的目的是测试中心假设，即T渠中T通道的CAV3.1同工型 CEM和VB丘脑核对麻醉诱导的催眠很重要。 为了检验这一假设，我们将使用急性脑切片和重组的体外贴片钳记录 体外和脑电图（EEG）记录的细胞在体内从CEM和VB核，选择性 药理学T通道抑制剂以及具有全球和区域特异性沉默的小鼠遗传学 Cav3.1在丘脑中追求以下特定目的： 目标1：确定重组和天然CAV3.1通道的生物物理和分子机制 通过两种常见气体，异氟烷（ISO）和Sevoflurane（sevo）在体外抑制，及其对neu-的影响 CEM的Ronal兴奋性。我们还将使用ISO（Azi-ISO）的光性配体的新方法和 sevo（azi-sevo）识别挥发性气体的CAV3.1通道上的特定分子结合位点。 目标2：确定CEM中的Cav3.1通道是否有助于丘脑皮质的改变 镇静/催眠期间的网络功能，挥发性气体和选择性T通道的给药 抑制剂TTA-P2，如体内脑电图记录所评估。 目标3：确定CEM和VB Thalamus中Cav3.1通道的区域特异性沉默是否会 ISO和SEVO诱导的体内镇静/催眠和丘脑皮质振荡的差异影响。 拟议的工作是创新的，因为麻醉引起的意识丧失的新机制将是 特征。它具有医学意义，因为它描述了靶向电压的药物的重要性 钙通道潜在发展临床麻醉的更安全实践。