16th European Headache Congress 2022 meeting abstracts

Abstract

Question: The neuropeptides calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating peptide (PACAP) are both implicated in migraine. Blocking the activity of these peptides simultaneously may provide a clinical advantage over individual blockade. One strategy is to develop a bifunctional ligand, capable of antagonizing both systems at once. As a starting point we utilized the known antagonism imparted by CGRP and PACAP peptide fragments, exploring different lengths of PACAP. From this, we selected CGRP 8-37 and PACAP 6-38 to attach together and assessed these molecules as bifunctional antagonists. Methods: Peptides were synthesized in-house and CGRP 8-37 was linked to PACAP 6-38 using 1,3-dipolar cycloaddition at amino acid positions 21, 34 and 38. The potency of these peptides as bifunctional antagonists was then tested, and compared to the parent fragments. We tested antagonism against CGRP at the human CGRP and AMY 1 receptors and against PACAP-27, PACAP-38 and VIP at the human PAC 1 , VPAC 1 and VPAC 2 receptors in Cos7 cells (cAMP production). Translational relevance was assessed by measuring antagonism of agonist-stimulated cAMP production in primary rat spinal cord cultures. Results: The bifunctional antagonists generally displayed similar antagonist activity to CGRP 8-37 and PACAP 6-38 in receptor transfected Cos7 cells and spinal cord cultures. Interestingly, linking CGRP 8-37 to position 38 of PACAP 6-38 generated a peptide with greater antagonist potency than CGRP 8-37 at CGRP and AMY 1 receptors in Cos7 cells. Conclusions: This study provides proof-of-concept that bifunctional antagonists capable of blocking both CGRP and PACAP activity can be generated. A2 Crosstalk between cannabinoid and vanilloid systems: role of CB receptors in the capsaicin-induced relaxation responses in human coronary arteries The Journal of Headache and Pain 2022, 23(Suppl 1):A2 Background: The use of cannabis and its derivatives has increased during the last years due to their therapeutic potential. However, the exact mechanisms of action of cannabinoids are still limited. It has been suggested that cannabinoids can exert their effects via the activation of cannabinoid receptors (i.e. CB 1 or CB 2 receptors) and/or transient receptor potential vanilloid 1 (TRPV1) channels, suggesting an interaction between both systems. We investigated the role of CB receptors in the vasodilatory effects induced by capsaicin in human isolated coronary arteries (HCAs). Methods: In HCAs (female, n=5; 56±5 years and male, n=4; 57±4 years), the vasodilatory responses to capsaicin (TRPV1 channel agon-ist) were evaluated in the absence or presence of the antagonists capsazepine (TRPV1, 5 μM); AM6545 (CB 1 receptor, 1 μM); AM630 (CB 2 receptor, 1 μM); O-1918 (putative endothelial CB receptor, 10 μM) or cannabidiol (GPR55 receptor, 1 μM) to obtain the maximum contractile response (E max). Results: Capsaicin induced concentration-dependent relaxation responses (E max 109±8%), which were significantly reduced by AM6545 (E max 87±4%) or cannabidiol (E max 86±3%), but not by capsazepine (E max 103±6%), AM630 (E max 100±3%) or O-1918 (E max 93±5%). Moreover , pilot experiments (n=2) showed that the maximal response induced by N-arachidonoylethanolamine, (ACEA, a CB 1 receptor agonist; E max 43±7%) is inhibited by AM6545 or capsazepine: E max 16±3% and 21±4%, respectively.