3 research outputs found
Identification of the First Synthetic Allosteric Modulator of the CB<sub>2</sub> Receptors and Evidence of Its Efficacy for Neuropathic Pain Relief
The direct activation
of cannabinoid receptors (CBRs) results in
several beneficial effects; therefore several CBRs ligands have been
synthesized and tested in vitro and in vivo. However, none of them
reached an advanced phase of clinical development due mainly to side
effects on the CNS. Medicinal chemistry approaches are now engaged
to develop allosteric modulators that might offer a novel therapeutic
approach to achieve potential therapeutic benefits avoiding inherent
side effects of orthosteric ligands. Here we identify the first ever
synthesized positive allosteric modulator (PAM) that targets CB<sub>2</sub>Rs. The evidence for this was obtained using [<sup>3</sup>H]ÂCP55940 and [<sup>35</sup>S]ÂGTPγS binding assays. This finding
will be useful for the characterization of allosteric binding site(s)
on CB<sub>2</sub>Rs which will be essential for the further development
of CB<sub>2</sub>R allosteric modulators. Moreover, the new CB<sub>2</sub>R PAM displayed antinociceptive activity in vivo in an experimental
mouse model of neuropathic pain, raising the possibility that it might
be a good candidate for clinical development
Identification of the First Synthetic Allosteric Modulator of the CB<sub>2</sub> Receptors and Evidence of Its Efficacy for Neuropathic Pain Relief
The direct activation
of cannabinoid receptors (CBRs) results in
several beneficial effects; therefore several CBRs ligands have been
synthesized and tested in vitro and in vivo. However, none of them
reached an advanced phase of clinical development due mainly to side
effects on the CNS. Medicinal chemistry approaches are now engaged
to develop allosteric modulators that might offer a novel therapeutic
approach to achieve potential therapeutic benefits avoiding inherent
side effects of orthosteric ligands. Here we identify the first ever
synthesized positive allosteric modulator (PAM) that targets CB<sub>2</sub>Rs. The evidence for this was obtained using [<sup>3</sup>H]ÂCP55940 and [<sup>35</sup>S]ÂGTPγS binding assays. This finding
will be useful for the characterization of allosteric binding site(s)
on CB<sub>2</sub>Rs which will be essential for the further development
of CB<sub>2</sub>R allosteric modulators. Moreover, the new CB<sub>2</sub>R PAM displayed antinociceptive activity in vivo in an experimental
mouse model of neuropathic pain, raising the possibility that it might
be a good candidate for clinical development
Enantiospecific Allosteric Modulation of Cannabinoid 1 Receptor
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)Âphysiological 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 <i>in vitro</i> and <i>ex vivo</i> pharmacology of the
novel allosteric CB1R modulator GAT211 (racemic) and its resolved
enantiomers, GAT228 (<i>R</i>) and GAT229 (<i>S</i>). GAT211 engages CB1R allosteric site(s), enhances the binding of
the orthosteric full agonist [<sup>3</sup>H]ÂCP55,490, and reduces
the binding of the orthosteric antagonist/inverse agonist [<sup>3</sup>H]ÂSR141716A. 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 <i>R-</i>(+)-enantiomer (GAT228), whereas its PAM
activity resided with the <i>S</i>-(−)-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