Development of high-affinity fluorinated ligands for cannabinoid subtype 2 receptor, and in vitro evaluation of a radioactive tracer for imaging

Design, synthesis, and structure–activity relationships of diindolylmethane derivatives as cannabinoid CB2 receptor agonists

“…Competition binding assays were performed using the nonselective CB receptor agonist radioligand [ 3 H](−)‐cis‐3‐[2‐hydroxy‐4‐(1,1‐dimethylheptyl)phenyl]‐trans‐4‐(3‐hydroxypropyl)cyclohexanol ([ 3 H]CP55,940, final concentration 0.1 nM) as previously described. [ 38,46,47 ] Membrane preparations of CHO cells stably expressing either human CB 1 or CB 2 receptor were used (CB 1 : 30 μg of protein/well and CB 2 : 16 µg of protein/well) for all of the radioligand binding experiments. Stock solutions of the DIM derivatives were prepared in DMSO.…”

“…β‐Arrestin recruitment assays based on galactosidase enzyme complementation assay (DiscoverX) were performed according to previously published. [ 38 ] Briefly, CHO β‐arrestin2 cells stably transfected either human CB 1 ‐prolink1 or human CB 2 ‐prolink1 were seeded in the density of 30,000 cells/well (CB 1 ), or 20,000 cells/well (CB 2 ), and incubated for 24 h. On the day of the assay, about 10 µl of the test compound was added and the cells were further incubated for another 90 min. CP 55,940 (0.1 µM) was used as the standard agonist for maximal response.…”

“…The nonspecific agonist radioligand [ 3 H]CP55,940 was used at a concentration of 0.1 nM for competition binding studies at both receptor subtypes. [21,30,38] For compounds that showed displacement of radioligand binding of more than 50%, full concentration-inhibition curves were determined, and K i values were calculated. Functional assays for the compounds that showed low micromolar K i values were performed to evaluate their agonistic (or antagonistic) activity.…”

Evaluation of cannabinoid type 2 receptor expression and pyridine-based radiotracers in brains from a mouse model of Alzheimer’s disease

“…Several CB 2 R ligands have been developed and evaluated (Ni et al, 2019b), including [ 11 C]NE40 (Vandeputte et al, 2012), [ 11 C]A-836339 (MDTC) (Pottier et al, 2017;Du et al, 2022), [ 18 F]MA3 (Attili et al, 2019), [ 18 F]FC0324 (Caillé et al, 2017), [ 18 F]JHU94620 (Moldovan et al, 2016), [ 18 F]LU13 (Gündel et al, 2022), [ 18 F]DM102 (Modemann et al, 2022), [ 18 F]CRA13 (Hassan et al, 2020), [ 11 C]RS-016 (Meletta et al, 2017), [ 11 C]RS-028 (Haider et al, 2018), [ 11 C]RSR-056 (Slavik et al, 2015), and [ 18 F]RoSMA-18-d6 (Haider et al, 2020). Thus far, only one in-human in vivo CB 2 R PET using [ 11 C]NE40 (Ahmad et al, 2016) in patients with AD and healthy controls has been reported, showing no group difference.…”

Evaluation of CB2R expression and pyridine-based radiotracers in brains from a mouse model of Alzheimer’s disease

“…CB 2 R has been shown to be increased and involved in Aβ pathology in 5×FAD [61,31] and J20 mouse models of AD amyloidosis [24] but reduced in the brains of 3×Tg mice (with both amyloid and tau pathology) and aging C57B6 mice [56]. Several CB 2 R ligands have been developed and evaluated [39], including [ 11 C]NE40 [54], [ 11 C]A-836339 (MDTC) [9,42], [ 18 F]MA3 [4], [ 18 F]FC0324 [6], [ 18 F]JHU94620 [35], [ 18 F]LU13 [14], [ 18 F]DM102 [34], [ 18 F]CRA13 [17], [ 11 C]RS-016 [32], [ 11 C]RS-028 [16], [ 11 C]RSR-056 [50] and [ 18 F]RoSMA-18-d6 [15]. Thus far, only one in-human in vivo CB 2 R PET using [ 11 C]NE40 [1] in patients with AD and healthy controls has been reported, showing no group difference.…”