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Systematic evaluation of a panel of 30 synthetic cannabinoid receptor agonists structurally related to MMB‐4en‐PICA, MDMB‐4en‐PINACA, ADB‐4en‐PINACA, and MMB‐4CN‐BUTINACA using a combination of binding and different CB1 receptor activation assays. Part III: The G protein pathway and critical comparison of different assays
Author(s) -
Grafinger Katharina Elisabeth,
Vandeputte Marthe M.,
Cannaert Annelies,
Ametovski Adam,
Sparkes Eric,
Cairns Elizabeth,
Juchli Patrick Osamu,
Haschimi Belal,
Pulver Benedikt,
Banister Samuel D.,
Stove Christophe P.,
Auwärter Volker
Publication year - 2021
Publication title -
drug testing and analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.065
H-Index - 54
eISSN - 1942-7611
pISSN - 1942-7603
DOI - 10.1002/dta.3054
Subject(s) - cannabinoid receptor agonists , population , receptor , phenylalanine , cannabinoid receptor , chemistry , synthetic cannabinoids , cannabinoid , g protein , in vitro , pharmacology , biochemistry , biology , medicine , amino acid , agonist , environmental health
The present work is the last of a three‐part study investigating a panel of 30 systematically designed synthetic cannabinoid receptor agonists (SCRAs) including features such as the 4‐pentenyl tail and varying head groups including amides and esters of l ‐valine (MMB, AB), l ‐ tert ‐leucine (ADB), and l ‐phenylalanine (APP), as well as adamantyl (A) and cumyl moieties (CUMYL). Here, we evaluated these SCRAs for their capacity to activate the human cannabinoid receptor 1 (CB 1 ) via indirect measurement of G protein recruitment. Furthermore, we comparatively evaluated the results obtained from three in vitro assays, based on the recruitment of β‐arrestin 2 (βarr2 assay) or Gα i protein (mini‐Gα i assay), or binding of [ 35 S]‐GTPγS. The observed efficacies ( E max ) varied depending on the conducted assay. Statistical analysis suggests that the population means of the relative intrinsic activity (RA i ) significantly differ for the [ 35 S]‐GTPγS assay and the other two assays, but the population means of the βarr2 and mini‐Gα i assays were not statistically different. Our data suggest that differences observed between the βarr2 and mini‐Gα i assays are the best predictor for ‘biased agonism’ towards βarr or G protein recruitment in our study. SCRAs carrying an ADB or MPP moiety as a head group tended to produce elevated E max values in the βarr2 assay, which might result in a tendency of these compounds to cause pronounced tolerance in users—a hypothesis that should be evaluated further by future studies. In general, a comparison of efficacies derived from different assays is difficult and should only be conducted very cautiously.