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大麻素抑制大鼠三叉神经节神经元ATP激活电流

申晶晶, 刘长金, 李爱, 胡新武, 陆永利, 陈蕾, 周莹, 刘烈炬

华中科技大学同济医学院生理学教研室.湖北,武汉 430030；杜克大学医学中心麻醉学和神经生物学系.北卡罗莱纳州 27710

摘要

该文在培养的大鼠三叉神经节（trigeminal ganglion，TG）神经元上采用全细胞膜片钳技术，探讨大麻素对大鼠TG神经元ATP激活电流（ATP--activated currents，I_(ATP)）的影响。结果显示：（1）胞外给予ATP，大部分受检细胞（67／75，89.33％）可记录到一个内向电流，且具有剂量依赖性。该电流可被P2X嘌呤受体特异性拮抗剂PPADS所阻断。（2）预加WIN55212--2[大麻素受体1（cannabinoidreceptor1，CB1受体）激动剂]可对I_(ATP)产生抑制作用，此作用呈剂量依赖性，并可被CB1受体特异性拮抗剂AM281阻断。预加不同浓度的WIN55212--2（1×10~(-13), 1×10~(-12), 1×10~(-11), 1×10~(-10), 1×10~(-9)和1×10~(-8) mol/L对I_(ATP)（1×10~(-4)mol／L ATP）的抑制作用分别为（8.14±3.14）％、（20.11±2.72）％、（46.62±3.51）％、（72.16±5.64）％、（80.21±2.80）％和（80.59±3.55）％。（3）预加WIN55212--2后I_(ATP)的浓度．反应曲线明显下移；最大反应浓度时的，一幅值减小了（58.02±4.21）％，而阈值基本不变；预加WIN55212--2前后曲线的EC_(50)值非常接近（1.15×10~(-4)mol／L vs 1.27×10~(-4)mol／L）。（4）预加forskolin[腺苷酸环化酶（adenylylcyclase，AC）激动剂]或8--Br--cAMP可以逆转WIN55212--2对I_(ATP)的抑制作用。以上结果表明，大麻素可能作用于CB1受体，通过抑制AC--cAMP--PKA途径发挥对I_(ATP)的抑制作用。

关键词： 大麻素受体1; WIN55212-2; P2X受体; 三叉神经节; 膜片钳技术

Cannabinoids inhibit ATP--activated currents in rat trigeminal ganglionic neurons

Shen Jingjing, Liu Changjin, Li Ai, Hu Xinwu, Lu Yongli, Chen Lei, Zhou Ying, Liu Lieju

Department of Physiology, Tongji Medical College, Huazhong University of Science and Technology.Wuhan 430030,Hubei；USA

Abstract

The present study aimed to investigate whether cannabinoids could modulate the response mediated by ATP receptor （P2X purinoceptor）. Whole-cell patch-clamp recording was performed on cultured rat trigeminal ganglionic （TG） neurons. The majority of TG neurons were sensitive to ATP （67/75, 89.33%）. Extracellular pretreatment with WIN55212-2, a cannabinoid receptor 1 （CB 1 receptor） agonist, reduced ATP-activated current （I_(ATP)） significantly. This inhibitory effect was concentration-dependent and was blocked by AM281, a specific CB 1 receptor antagonist. Pretreatment with WIN55212-2 at 1×10~(-13), 1×10~(-12), 1×10~(-11), 1×10~(-10), 1×10~(-9) and 1×10~(-8) mol/L reduced I_(ATP) （induced by 1×10~(-4) mol/L ATP） by （8.14±3.14）%, （20.11±2.72）%, （46.62±3.51）%, （72.16±5.64）%, （80.21±2.80）% and （80.59±3.55）%, respectively. The concentration-response curves for I_(ATP) pretreated with and without WIN55212-2 showed that WIN55212-2 shifted the curve downward, and decreased the maximal amplitude of I_(ATP) by （58.02±4.21）%. But the threshold value and EC_(50) （1.15×10~(-4) mol/L vs 1.27×10~(-4) mol/L） remained unchanged. The inhibition of I_(ATP) by WIN55212-2 was reversed by AM281, suggesting that the inhibition was mediated via the CB 1 receptor. Pretreatment with forskolin [an agonist of adenylyl cyclase （AC）] or 8-Br-cAMP reversed the inhibition of I_(ATP) by WIN55212-2. These results suggest that the inhibitory effect of cannabinoids on I_(ATP) is mediated via the CB 1 receptors, that lead to inhibition of the AC-cAMP-PKA signaling pathway.

Key words: cannabinoid receptor 1;WIN55212-2;P2X receptor;trigeminal ganglion;patch-clamp technique

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引用本文：

申晶晶, 刘长金, 李爱, 胡新武, 陆永利, 陈蕾, 周莹, 刘烈炬. 大麻素抑制大鼠三叉神经节神经元ATP激活电流[J]. 生理学报 2007; 59 (6): 745-752.

Shen Jingjing, Liu Changjin, Li Ai, Hu Xinwu, Lu Yongli, Chen Lei, Zhou Ying, Liu Lieju. Cannabinoids inhibit ATP--activated currents in rat trigeminal ganglionic neurons. Acta Physiol Sin 2007; 59 (6): 745-752 (in Chinese with English abstract).