Rat brain cannabinoid receptor modulates N-type Ca2+ channels in a neuronal expression system.
Rat brain cannabinoid receptor modulates N-type Ca2+ channels in a neuronal expression system.
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发表时间：
1996-04
影响因子：
3.6
通讯作者：
Xianghua Pan;Stephen R. Ikeda;Deborah L. Lewis
中科院分区：
文献类型：
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作者：
Xianghua Pan;Stephen R. Ikeda;Deborah L. Lewis
利用异源神经元表达系统研究了克隆的大鼠脑CB 1大麻素受体对神经元离子通道的调节作用。通过将体外转录的cRNA显微注射到酶促分离的成年大鼠上级颈神经节神经元的细胞质中，实现大鼠脑CB 1大麻素受体的瞬时表达。大麻拟氨烷基吲哚WIN 55，212 -2抑制16-25小时前注射大鼠脑CB 1大麻素受体cRNA的神经元中的全细胞Ca 2+电流。对Ca 2+电流的抑制具有电压和浓度依赖性，最大抑制率为73%，IC 50值为47 nM。合成大麻素类似物CP 55，940也抑制Ca 2+电流，最大抑制率为38%，IC 50值为7 nM。钙电流的抑制作用可通过在细胞内贴片移液器溶液中加入鸟苷-5 '-O-（2-硫代二磷酸）或用百日咳毒素预处理来阻断。用N型Ca 2+通道拮抗剂ω-芋螺毒素GVIA预处理将100 nM WIN 55，212 -2的抑制从44%降低至6%，表明N型Ca 2+通道是大麻素作用的靶标。在WIN 55，212 -2洗脱时，在47%的测试神经元中，Ca 2+电流幅度“过度恢复”。内源性拟大麻化合物Anandamide对大多数用大麻素受体cRNA显微注射的神经元中的电压依赖性Ca 2+电流具有不一致的影响。Ca 2+通道是大麻素受体的特异性效应靶点，因为两种不同的K+电流，M电流和A电流，不受大麻模拟物WIN 55，212 -2的调节。
Modulation of neuronal ion channels by the cloned rat brain CB1 cannabinoid receptor was investigated with the use of a heterologous neuronal expression system. Transient expression of the rat brain CB1 cannabinoid receptor was accomplished through microinjection of in vitro transcribed cRNA into the cytoplasm of enzymatically dissociated adult rat superior cervical ganglion neurons. The cannabimimetic aminoalkylindole WIN 55,212-2 inhibited whole-cell Ca2+ currents in neurons injected 16-25 hr previously with rat brain CB1 cannabinoid receptor cRNA. Inhibition of the Ca2+ current was voltage and concentration dependent, with a maximal inhibition of 73% and an IC50 value of 47 nM. The synthetic cannabinoid analogue CP55,940 also inhibited Ca2+ currents, with a maximal inhibition of 38% and an IC50 value of 7 nM. Ca2+ current inhibition was blocked by inclusion of guanosine-5'-O-(2-thiodiphosphate) in the intracellular patch pipette solution or by pretreatment with pertussis toxin. Pretreatment with the N-type Ca2+ channel antagonist omega-conotoxin GVIA reduced the inhibition by 100 nM WIN 55,212-2 from 44% to 6%, indicating that N-type Ca2+ channels are a target of cannabinoid action. On washout of WIN 55,212-2, the Ca2+ current amplitude "overrecovered" in 47% of the neurons tested. Anandamide, the endogenous cannabimimetic compound, had an inconsistent effect on the voltage-dependent Ca2+ currents in the majority of neurons microinjected with cannabinoid receptor cRNA. Ca2+ channels were a specific effector target of the cannabinoid receptor, as two different K+ currents, the M current and the A current, were not modulated by the cannabimimetic WIN 55,212-2.