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Basic and systemic mechanisms of anesthesia -Molecular structure and dynamics of neuronal receptor channel proteins in anesthetic action-

麻醉的基本和全身机制-麻醉作用中神经元受体通道蛋白的分子结构和动力学-

基本信息

批准号：
16209047
负责人：
MASHIMO TAKASHI
金额：
$ 22.46万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2007
项目状态：
已结题

项目摘要

Molecular identifications of general anesthetic targets in the receptor level has been progressed and the functional roles of their molecular targets are revealed by their integration of the in vivo system using the genetic engineering techniques.1) Xenon suppresses nociceptive reflex in rat spinal cord in vitro ; comparison with nitrous oxide : The effect of xenon on slow ventral root potential and monosynaptic reflex in neonatal rat spinal cord in vitro in comparison with nitrous oxide. Xenon and nitrous oxide significantly reduced the amplitudes of both slow ventral root potential and monosynaptic reflex The results indicate that xenon and nitrous oxide suppress the synaptic transmission at the spinal cord, especially those of the slow ventral root potential, which refrect nociceptive transmission.2) Formation of signal transduction complexes during immobile phase of NGF-receptor movements : The single-molecule imaging was used to characterize the behavior of Cy3-stagged NGF after b … More inding to receptor complexes on the surface of PC12 cell NGF-receptor complexes have two distinct diffusive states, characterized as mobile and immobile phase. The transition between the two diffusive states occurred reversibly with duration times determined by a single rate limiting process. Immobilization depended on the phosphorylation of the TrkA NGF-receptor. NGF signaling is performed through a repetitive random process to induce transition formation of signaling complexes.3) General anesthetics potentiate GABAergic tonic inhibition of substantia gelatinosa neurons in mouse spinal cord.: Whole-cell recording was used to identify GABAergic tonic current in subpopulations of substantia gelatinosa neurons in mouse spinal cord slims. Application of the GABAA receptor antagonist bicuculline revealed tonic currents in some neurons for the first time. General anesthetics, midazolam and propofol potentiated these tonic currents. The presence of mRNAs for α4, α5, δ and εsubunits in the substantia geratinosa suggest that GABAAreceptors α5βxγ2 subunits are responsible for tonic currents.4) Local anesthetics have different mechanisms and sites of action at recombinant 5-HT3 receptors : The cRNAs from human wild-type and 4 mutant 5-HT3A subunit clones were synthesized in vitro and expressed in Xenopus oocytes. Four mutant receptor were obtained by site-directed mutagenesis in the N-terminal extracellular region. The 2-electrode voltage clamp technique was used to measure peak currents induced by 5-HT in these receptors in the presence and absence of local anesthetics. All local anesthetics inhibited 5-HT-induced currents in the wild-type receptor. Inhibition by procaine and tetracaine were competitive whereas those of bupivacaine and lidocaine were both noncompetitive and competitive. All mutant receptors exhibited 10-fold increase in the half-maximum inhibitory concentration for procaine. The half-maximum inhibitory concentrations of tetracaine, bupivacaine, and lidocaine in mutant receptors were increased 2- to 3-fold. These results suggest that the ester type local anesthetics, procaine and tetracaine may act at a different site on the 5-HT3Areceptor and with a different mechanism than the amide-type local anesthetics. Less

在受体水平上对全身麻醉靶点的分子鉴定已经取得了进展，并且通过使用基因工程技术将其整合到体内系统中来揭示其分子靶点的功能作用。1）氙在体外抑制大鼠脊髓的伤害性反射;与一氧化二氮的比较：氙气与氧化亚氮对离体新生大鼠脊髓腹根慢电位和单突触反射影响的比较。氙和一氧化二氮均能显著降低背根慢电位和单突触反射的振幅。结果表明氙和一氧化二氮抑制脊髓的突触传递，尤其是背根慢电位，从而抑制伤害性信息的传递。采用单分子成像技术对B处理后Cy 3-stagged NGF的行为进行了表征 ...更多信息在PC 12细胞表面的NGF受体复合物上的结合具有两种不同的扩散状态，其特征在于移动的和非移动的相。两个扩散状态之间的过渡发生可逆的持续时间由一个单一的速率限制过程。固定依赖于TrkA NGF受体的磷酸化。NGF信号传导通过重复的随机过程进行，以诱导信号传导复合物的转变形成。3）全身麻醉剂增强小鼠脊髓中胶状质神经元的GABA能紧张性抑制。用全细胞记录技术研究了小鼠脊髓胶状质神经元亚群的GABA能紧张性电流。应用GABAA受体拮抗剂荷包牡丹碱首次在某些神经元中发现了紧张性电流。全身麻醉药咪达唑仑和丙泊酚增强了这些紧张性电流。结果表明，GABAA受体α5βxγ2亚基与紧张性电流有关。4）局麻药对重组5-HT 3受体的作用机制和作用位点不同：体外合成人野生型和4种突变型5-HT 3A亚基克隆的cRNA，并在非洲爪蟾卵母细胞中表达。在N端胞外区进行定点突变，获得了4个突变受体。采用双电极电压钳技术，在有和无局麻药的情况下，测量5-HT在这些受体上诱导的峰电流。所有局麻药抑制5-HT诱导的电流在野生型受体。普鲁卡因和丁卡因的抑制是竞争性的，而布比卡因和利多卡因的抑制是非竞争性和竞争性的。所有突变受体表现出10倍的增加，普鲁卡因的半最大抑制浓度。丁卡因、布比卡因和利多卡因在突变受体中的半最大抑制浓度增加2- 3倍。这些结果提示，酯型局麻药普鲁卡因和丁卡因可能作用于5-HT_3A受体的不同部位，其作用机制与酰胺型局麻药不同。少