大麻素抑制大鼠三叉神经节神经元ATP激活电流(英文)

Cannabinoids inhibit ATP-activated currents in rat trigeminal ganglionic neurons

本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(cannabinoid receptor 1,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I_(ATP)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(adenylyl cyclase,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。

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 （IATP） 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 IATP （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 IATP pretreated with and without WIN55212-2 showed that WIN55212-2 shifted the curve downward, and decreased the maximal amplitude of IATP by （58.02±4.21）%. But the threshold value and EC50 （1.15× 10^-4 mol/L vs 1.27× 10^-4 mol/L） remained unchanged. The inhibition of IATP 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 IATP by WIN55212-2. These results suggest that the inhibitory effect of cannabinoids on IATP is mediated via the CB 1 receptors, that lead to inhibition of the AC-cAMP-PKA signaling pathway.