背景:基于目前对神经肽信号在偏头痛中的作用的理解,我们探索了特定大麻素激动剂的治疗潜力.本研究的目的是检查合成内源性大麻素(eCB)类似物的作用,花生四酰基-2'-氯乙基酰胺(ACEA),降钙素基因相关肽(CGRP)在硬脑膜和三叉神经节(TG)中的释放,由于已知大麻素激活GI/O偶联大麻素受体1型(CB1),导致神经元抑制。
方法:使用半颅骨模型和解剖的雄性Sprague-Dawley大鼠的TG进行实验。CGRP释放由60mMK(用于去极化诱导的刺激)或100nM辣椒素(用于瞬时受体电位香草素1(TRPV1)诱导的刺激)诱导,并使用酶联免疫吸附测定进行测量。CGRP释放数据的分析与免疫组织化学相结合,以研究CB1,大麻素受体2型(CB2)的细胞定位,CGRP和受体活性修饰蛋白1(RAMP1),功能性CGRP受体的一个亚基,在TG。
结果:CB1主要在观察到与CGRP共定位的神经元体细胞中表达。此外,CB1在神经元Aδ纤维中表现出与RAMP1的共定位,但在CGRP免疫反应性C纤维中并未明确表达。CB2主要在卫星神经胶质细胞中表达,并且与CGRP或RAMP1均未显示出实质性的共定位。没有刺激,140nMACEA本身引起硬脑膜CGRP释放的显着增加,而不是TG,与车辆相比。此外,140nMACEA没有显着改变K-或辣椒素诱导的CGRP释放。然而,当TRPV1阻断剂AMG9810(1mM)与ACEA共同应用时,在TG和硬脑膜中,K诱导的CGRP释放显着减弱。
结论:本研究的结果表明,ACEA本身由于其双重激动特性而不表现出抗偏头痛的潜力,导致CB1和TRPV1的激活,从而抑制和刺激CGRP释放,分别。
BACKGROUND: Based on the current understanding of the role of neuropeptide signalling in migraine, we explored the therapeutic potential of a specific cannabinoid agonist. The aim of the present study was to examine the effect of the synthetic endocannabinoid (eCB) analogue, arachidonyl-2\'-chloroethylamide (
ACEA), on calcitonin gene-related peptide (CGRP) release in the dura and trigeminal ganglion (TG), as cannabinoids are known to activate Gi/o-coupled cannabinoid receptors type 1 (CB1), resulting in neuronal inhibition.
METHODS: The experiments were performed using the hemi-skull model and dissected TGs from male Sprague-Dawley rats. CGRP release was induced by either 60 mM K+ (for depolarization-induced stimulation) or 100 nM capsaicin (for transient receptor potential vanilloid 1 (TRPV1) -induced stimulation) and measured using an enzyme-linked immunosorbent assay. The analysis of CGRP release data was combined with immunohistochemistry in order to study the cellular localization of CB1, cannabinoid receptor type 2 (CB2), CGRP and receptor activity modifying protein 1 (RAMP1), a subunit of the functional CGRP receptor, in the TG.
RESULTS: CB1 was predominantly expressed in neuronal somas in which colocalization with CGRP was observed. Furthermore, CB1 exhibited colocalization with RAMP1 in neuronal Aδ-fibres but was not clearly expressed in the CGRP-immunoreactive C-fibres. CB2 was mainly expressed in satellite glial cells and did not show substantial colocalization with either CGRP or RAMP1. Without stimulation, 140 nM
ACEA per se caused a significant increase in CGRP release in the dura but not TG, compared to vehicle. Furthermore, 140 nM
ACEA did not significantly modify neither K+- nor capsaicin-induced CGRP release. However, when the TRPV1 blocker AMG9810 (1 mM) was coapplied with
ACEA, K+-induced CGRP release was significantly attenuated in the TG and dura.
CONCLUSIONS: Results from the present study indicate that
ACEA per se does not exhibit antimigraine potential due to its dual agonistic properties, resulting in activation of both CB1 and TRPV1, and thereby inhibition and stimulation of CGRP release, respectively.