Molecular signaling of synthetic cannabinoids: Comparison of CB1 receptor and TRPV1 channel activation

• Published in: European journal of pharmacology 2021-09, Vol.907, p.174301-174301, Article 174301
• Main Authors: Andersen, Haley K., Walsh, Kenneth B.
• Format: Article
• Language: English
• Subjects: Animals; Calcium - metabolism; Cannabinoids - metabolism; Cannabinoids - pharmacology; Fluorescence measurements; G Protein-Coupled Inwardly-Rectifying Potassium Channels - metabolism; G protein-gated inward rectifier K+ channel; HEK293 Cells; Humans; Receptor, Cannabinoid, CB1 - agonists; Receptor, Cannabinoid, CB1 - metabolism; Signal Transduction - drug effects; Synthetic cannabinoids; Transient potential receptor channels; TRPV Cation Channels - agonists; TRPV Cation Channels - metabolism
• ISSN: 0014-2999; 1879-0712; 1879-0712
• DOI: 10.1016/j.ejphar.2021.174301

Recreational use of synthetic cannabinoids (SCs) is associated with desirable euphoric and relaxation effects as well as adverse effects including anxiety, agitation and psychosis. These SC-mediated actions represent a combination of potentiated cannabinoid receptor signaling and “off-target” receptor activity. The goal of this study was to compare the efficacy of various classes of SCs in stimulating CB1 receptors and activating “off-target” transient receptor potential (TRP) channels. Cannabinoid-type 1 (CB1) receptor activity was determined by measuring SC activation of G protein-gated inward rectifier K+ (GIRK) channels using a membrane potential-sensitive fluorescent dye assay. SC opening of vanilloid type-1 (TRPV1) channels was measured by recording intracellular Ca2+ transients. All of the SCs tested activated the GIRK channel with an efficacy of 4-fluoro MDMB-BUTINACA > 5-fluoro MDMB-PICA > MDMB-4en-PINACA ≈ WIN 55,212-2 > AB-FUBINACA > AM1220 ≈ JWH-122 N-(5-chloropentyl) > AM1248 > JWH-018 ≈ XLR-11 ≈ UR-144. The potency of the SCs at the CB1 receptor was 5-fluoro MDMB-PICA ≈ 4-fluoro MDMB-BUTINACA > AB-FUBINACA ≈ MDMB-4en-PINACA > JWH-018 > AM1220 > XLR-11 > JWH-122 N-(5-chloropentyl) > WIN 55,212-2 ≈ UR-144 > AM1248. In contrast, when tested at a SC concentration that produced a maximal effect on the Gi/GIRK channel, only XLR-11, UR-144 and AM1220 caused a significant activation of the TRPV1 channels. The TRPV1 channel/Ca2+ signal measured during application of 10 μM XLR-11 was similar to the signal induced by the endocannabinoid N-arachidonoylethanolamine (AEA). Thus, while various SCs share the ability to stimulate CB1 receptor/Gi signaling, they display limited efficacy in opening TRPV1 channels.