TY - JOUR
T1 - Enantiospecific Allosteric Modulation of Cannabinoid 1 Receptor
AU - Laprairie, Robert B.
AU - Kulkarni, Pushkar M.
AU - Deschamps, Jeffrey R.
AU - Kelly, Melanie E.M.
AU - Janero, David R.
AU - Cascio, Maria G.
AU - Stevenson, Lesley A.
AU - Pertwee, Roger G.
AU - Kenakin, Terrence P.
AU - Denovan-Wright, Eileen M.
AU - Thakur, Ganesh A.
N1 - Funding Information:
This work was supported by a partnership grant from CIHR, Nova Scotia Health Research Foundation (NSHRF), and the Huntington Society of Canada (HSC) (ROP-97185) to E.D.W., a CIHR operating grant (MOP-97768) to M.E.M.K., and grants from NIH/National Eye Institute (EY024717 to G.A.T., R.G.P., and M.E.K.). R.B.L. is supported by studentships from CIHR, HSC, Killam Trusts and NSHRF. The X-ray crystallographic work was supported by the United States National Institutes on Drug Abuse (NIDA) through Interagency Agreement No. Y1-DA1101 with the Naval Research Laboratory.
Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/6/21
Y1 - 2017/6/21
N2 - The cannabinoid 1 receptor (CB1R) is one of the most widely expressed metabotropic G protein-coupled receptors in brain, and its participation in various (patho)physiological processes has made CB1R activation a viable therapeutic modality. Adverse psychotropic effects limit the clinical utility of CB1R orthosteric agonists and have promoted the search for CB1R positive allosteric modulators (PAMs) with the promise of improved drug-like pharmacology and enhanced safety over typical CB1R agonists. In this study, we describe the synthesis and in vitro and ex vivo pharmacology of the novel allosteric CB1R modulator GAT211 (racemic) and its resolved enantiomers, GAT228 (R) and GAT229 (S). GAT211 engages CB1R allosteric site(s), enhances the binding of the orthosteric full agonist [3H]CP55,490, and reduces the binding of the orthosteric antagonist/inverse agonist [3H]SR141716A. GAT211 displayed both PAM and agonist activity in HEK293A and Neuro2a cells expressing human recombinant CB1R (hCB1R) and in mouse-brain membranes rich in native CB1R. GAT211 also exhibited a strong PAM effect in isolated vas deferens endogenously expressing CB1R. Each resolved and crystallized GAT211 enantiomer showed a markedly distinctive pharmacology as a CB1R allosteric modulator. In all biological systems examined, GAT211's allosteric agonist activity resided with the R-(+)-enantiomer (GAT228), whereas its PAM activity resided with the S-(-)-enantiomer (GAT229), which lacked intrinsic activity. These results constitute the first demonstration of enantiomer-selective CB1R positive allosteric modulation and set a precedent whereby enantiomeric resolution can decisively define the molecular pharmacology of a CB1R allosteric ligand.
AB - The cannabinoid 1 receptor (CB1R) is one of the most widely expressed metabotropic G protein-coupled receptors in brain, and its participation in various (patho)physiological processes has made CB1R activation a viable therapeutic modality. Adverse psychotropic effects limit the clinical utility of CB1R orthosteric agonists and have promoted the search for CB1R positive allosteric modulators (PAMs) with the promise of improved drug-like pharmacology and enhanced safety over typical CB1R agonists. In this study, we describe the synthesis and in vitro and ex vivo pharmacology of the novel allosteric CB1R modulator GAT211 (racemic) and its resolved enantiomers, GAT228 (R) and GAT229 (S). GAT211 engages CB1R allosteric site(s), enhances the binding of the orthosteric full agonist [3H]CP55,490, and reduces the binding of the orthosteric antagonist/inverse agonist [3H]SR141716A. GAT211 displayed both PAM and agonist activity in HEK293A and Neuro2a cells expressing human recombinant CB1R (hCB1R) and in mouse-brain membranes rich in native CB1R. GAT211 also exhibited a strong PAM effect in isolated vas deferens endogenously expressing CB1R. Each resolved and crystallized GAT211 enantiomer showed a markedly distinctive pharmacology as a CB1R allosteric modulator. In all biological systems examined, GAT211's allosteric agonist activity resided with the R-(+)-enantiomer (GAT228), whereas its PAM activity resided with the S-(-)-enantiomer (GAT229), which lacked intrinsic activity. These results constitute the first demonstration of enantiomer-selective CB1R positive allosteric modulation and set a precedent whereby enantiomeric resolution can decisively define the molecular pharmacology of a CB1R allosteric ligand.
KW - 7-transmembrane receptor
KW - Allosteric regulation
KW - cannabinoid
KW - cellular signaling
KW - central nervous system
KW - G-protein-coupled receptor
KW - ligand bias
KW - molecular pharmacology
KW - probe dependence
KW - receptor activation
KW - therapeutics discovery
UR - http://www.scopus.com/inward/record.url?scp=85021100824&partnerID=8YFLogxK
U2 - 10.1021/acschemneuro.6b00310
DO - 10.1021/acschemneuro.6b00310
M3 - Article
C2 - 28103441
AN - SCOPUS:85021100824
VL - 8
SP - 1188
EP - 1203
JO - ACS Chemical Neuroscience
JF - ACS Chemical Neuroscience
SN - 1948-7193
IS - 6
ER -