Analysis of nociceptin-induced spontaneous transient outward currents and their physiological function in the CNS

自发性瞬时外向电流（STOCs）在外周神经元和平滑肌细胞中发现，但在中枢神经元中很少发现。利用制霉菌素穿孔膜片钳技术，我们成功地记录了小鼠齿状回颗粒细胞的STOCs。孤啡肽增加STOCs的振幅和频率。我们认为对STOCs的调节是中枢神经元细胞活动调节的一种新手段，并研究了STOCs的特性和增强机制。全细胞的电流-电压关系表现为外向整流，其反转电位接近钾的平衡电位。四乙基铵、伊比利亚毒素和钙离子螯合剂BAPTA-AM抑制STOCs。这些结果表明，大电导Ca^<2+>激活的K^+通道参与其中。由内而外结构的单通道记录显示，Ca^2+激活的K^+通道的电导范围为82 - 352 p ...更多信息 S.孤啡肽（1-13）NH可消除孤啡肽的增强效应。Cd^<2+>不影响瞬时外向电流或伤害感受素的增强作用.而痛敏素，茶碱和环ADP核糖诱导短暂的外向电流与对照条件下观察到的，肌醇1，4，5-三磷酸诱导短暂的外向电流与长时间，除了那些与短时间。Ryanodine抑制nociceptin增加STOCs。我们的数据表明，是Ca^2+火花，而不是Ca^2+夸克，瞬时激活大电导Ca激活的K^+通道，从而诱导瞬时外向电流。孤啡肽可能使兰尼碱受体敏感，并增加瞬时外向电流，从而降低细胞的兴奋性。甚至在孤啡肽受体敲除小鼠中也观察到孤啡肽诱导的STOC振幅和频率的增加，表明受体亚型的存在。本研究首次揭示了STOCs在中枢神经系统中的存在、特点以及G蛋白偶联受体对STOCs的调节作用。少

Spontaneous transient outward currents (STOCs) have been found in peripheral neurons and smooth muscle cells, but rarely in central neurons. Using a nystatin-perforated patch clamp technique, we succeeded in recording STOCs in mouse dentate gyrus granule cells. Nociceptin increased the amplitude and frequency of STOCs. We consider modulation of STOCs to be a new means to regulate cell activity in central neurons, and studied their characteristics and mechanism of augmentation. The whole-cell current-voltage relationship showed outward rectification and the reversal potential was close to the equilibrium potential for K The frequency of STOCs increased at depolarized potentials. Tetraethylammonium, iberiotoxin and a Ca^<2+> chelator BAPTA-AM inhibited STOCs. These results suggest the involvement of large-conductance Ca^<2+>-activated K^+ channels. Single-channel recordings in the inside-out configuration revealed Ca^<2+>-activated K^+ channels with a conductance ranging from 82 to 352 p … More S. The augmenting effect of nociceptin was cancelled by [Phe^1Ψ(CH -NH)Gly^2]Nociceptin(1-13)NH. Cd^<2+> did not affect the transient outward currents or augmentation by nociceptin. Whereas nociceptin, theophylline and cyclic ADP ribose induced transient outward currents with short duration observed under control conditions, inositol 1, 4, 5-trisphosphate induced transient outward currents with long duration, in addition to those with short duration. Ryanodine inhibited nociceptin from augmenting STOCs. Our data suggest that Ca^<2+> sparks, not Ca^<2+> quarks, transiently activate large-conductance Ca -activated K^+ channels to induce transient outward currents Nociceptin probably sensitizes ryanodine receptors and increases transient outward currents to reduce cell excitability. Nociceptin-induced increase in the amplitude and frequency of STOCs was observed even in the nociceptin receptor knockout mice, suggesting the presence of receptor subtype. In this study, we first revealed the presence and the characteristics of STOCs in the CNS and the modulation of STOCs by G protein coupled receptor. Less