Sheykhzade Majid, Amandi Nilofar, Pla Monica Vidal, Abdolalizadeh Bahareh, Sams Anette, Warfvinge Karin, Edvinsson Lars, Pickering Darryl S
Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
Vascul Pharmacol. 2017 Mar;90:36-43. doi: 10.1016/j.vph.2017.02.001. Epub 2017 Feb 10.
The neuropeptide calcitonin gene-related peptide (CGRP) is found in afferent sensory nerve fibers innervating the resistance arteries and plays a pivotal role in a number of neurovascular diseases such as migraine and subarachnoid bleedings. The present study investigates the binding and antagonistic characteristics of small non-peptide CGRP receptor antagonists (i.e. gepants) in isolated rat brain and mesenteric resistance arteries.
The antagonistic behavior of gepants was investigated in isolated rat mesenteric arteries using a wire myograph setup while binding of gepants to CGRP receptors was investigated in rat brain membranes using a radioligand competitive binding assay. Furthermore, the histological location of the key components of CGRP receptor (RAMP1 and CLR) was assessed by immunohistochemistry.
Our functional studies clearly show that all gepants are reversible competitive antagonists producing Schild plot slopes not significantly different from unity and thus suggesting presence of a uniform CGRP receptor population in the arteries. A uniform receptor population was also confirmed by radioligand competitive binding studies showing similar affinities for the gepants in rat brain and mesenteric arteries, the exception being rimegepant which had 50-fold lower affinity in brain than mesenteric arteries. CLR and RAMP1 were shown to be located in both vascular smooth muscle and endothelial cells of rat mesenteric arteries by immunohistochemistry.
The present results indicate that, despite species differences in the CGRP receptor affinity, the antagonistic nature of these gepants, the distribution pattern of CGRP receptor components and the mechanism behind CGRP-induced vasodilation seem to be similar in resistance-sized arteries of human and rats.
神经肽降钙素基因相关肽（CGRP）存在于支配阻力动脉的传入感觉神经纤维中，在偏头痛和蛛网膜下腔出血等多种神经血管疾病中起关键作用。本研究调查了小分子非肽类CGRP受体拮抗剂（即gepants）在离体大鼠脑和肠系膜阻力动脉中的结合及拮抗特性。
使用线肌张力测定装置在离体大鼠肠系膜动脉中研究gepants的拮抗行为，同时使用放射性配体竞争结合试验在大鼠脑膜中研究gepants与CGRP受体的结合。此外，通过免疫组织化学评估CGRP受体关键成分（RAMP1和CLR）的组织学定位。
我们的功能研究清楚地表明，所有gepants都是可逆性竞争性拮抗剂，其施尔德图斜率与1无显著差异，因此提示动脉中存在均匀的CGRP受体群体。放射性配体竞争结合研究也证实了受体群体的一致性，显示gepants在大鼠脑和肠系膜动脉中的亲和力相似，例外的是利美尼定，其在脑中的亲和力比肠系膜动脉低50倍。免疫组织化学显示CLR和RAMP1位于大鼠肠系膜动脉的血管平滑肌和内皮细胞中。
目前的结果表明，尽管CGRP受体亲和力存在种属差异，但这些gepants的拮抗性质、CGRP受体成分的分布模式以及CGRP诱导血管舒张的机制在人和大鼠的阻力动脉中似乎相似。
