Analgesic Effect of a Mixed T-Type Channel Inhibitor/CB2 Receptor Agonist. (1st July 2013)

• Record Type: Journal Article
• Authors: Gadotti, Vinicius M; You, Haitao; Petrov, Ravil R; Berger, N Daniel; Diaz, Philippe; Zamponi, Gerald W
• Is Part Of: Molecular pain. Volume 9(2013)
• Publication Date: 2013-07-01
• Subjects: T-type Channels -- Cannabinoid Receptors -- Pain -- Patch-Clamp -- Mice; Pain -- Molecular aspects -- Periodicals; Pain -- Pathophysiology -- Periodicals; Pain -- Physiological aspects -- Periodicals; 616.0472
• DOI: 10.1186/1744-8069-9-32
• Languages: English
• ISSNs: 1744-8069

Abstract

Background: Cannabinoid receptors and T-type calcium channels are potential targets for treating pain. Here we report on the design, synthesis and analgesic properties of a new mixed cannabinoid/T-type channel ligand, NMP-181. Results: NMP-181 action on CB1 and CB2 receptors was characterized in radioligand binding and in vitro GTPγ[ 35 S] functional assays, and block of transiently expressed human Cav3.2 T-type channels by NMP-181 was analyzed by patch clamp. The analgesic effects and in vivo mechanism of action of NMP-181 delivered spinally or systemically were analyzed in formalin and CFA mouse models of pain. NMP-181 inhibited peak Cav3.2 currents with IC50 values in the low micromolar range and acted as a CB2 agonist. Inactivated state dependence further augmented the inhibitory action of NMP-181. NMP-181 produced a dose-dependent antinociceptive effect when administered either spinally or systemically in both phases of the formalin test. Both i.t. and i.p. treatment of mice with NMP-181 reversed the mechanical hyperalgesia induced by CFA injection. NMP-181 showed no antinocieptive effect in Cav 3.2 null mice. The antinociceptive effect of intrathecally delivered NMP-181 in the formalin test was reversed by i.t. treatment of mice with AM-630 (CB2 antagonist). In contrast, the NMP-181-induced antinociception was not affected by treatment of mice with AM-281 (CB1 antagonist). Conclusions: Our work shows that both T-type channels as well as CB2 receptors play a role in the antinociceptive action of NMP-181, and also provides a novel avenue for suppressing chronic pain through novel mixed T-type/cannabinoid receptor ligands.