Daniele Bolognini

Cannabidiol, a non‐psychotropic component of cannabis, attenuates vomiting and nausea‐like behaviour via indirect agonism of 5‐HT1A somatodendritic autoreceptors in the dorsal raphe nucleus

BACKGROUND AND PURPOSE To evaluate the hypothesis that activation of somatodendritic 5‐HT1A autoreceptors in the dorsal raphe nucleus (DRN) produces the anti‐emetic/anti‐nausea effects of cannabidiol (CBD), a primary non‐psychoactive cannabinoid found in cannabis.

The plant cannabinoid Δ9-tetrahydrocannabivarin can decrease signs of inflammation and inflammatory pain in mice

Background and purpose:  The phytocannabinoid, Δ9‐tetrahydrocannabivarin (THCV), can block cannabinoid CB1 receptors. This investigation explored its ability to activate CB2 receptors, there being evidence that combined CB2 activation/CB1 blockade would ameliorate certain disorders.

CB1 Receptor Allosteric Modulators Display Both Agonist and Signaling Pathway Specificity

We have previously identified allosteric modulators of the cannabinoid CB1 receptor (Org 27569, PSNCBAM-1) that display a contradictory pharmacological profile: increasing the specific binding of the CB1 receptor agonist [3H]CP55940 but producing a decrease in CB1 receptor agonist efficacy. Here we investigated the effect one or both compounds in a broad range of signaling endpoints linked to CB1 receptor activation. We assessed the effect of these compounds on CB1 receptor agonist–induced [35S]GTPγS binding, inhibition, and stimulation of forskolin-stimulated cAMP production, phosphorylation of extracellular signal-regulated kinases (ERK), and β-arrestin recruitment. We also investigated the effect of these allosteric modulators on CB1 agonist binding kinetics. Both compounds display ligand dependence, being significantly more potent as modulators of CP55940 signaling as compared with WIN55212 and having little effect on [3H]WIN55212 binding. Org 27569 displays biased antagonism whereby it inhibits: agonist-induced guanosine 5′-O-(3-[35S]thio)triphosphate ([35S]GTPγS) binding, simulation (Gαs-mediated), and inhibition (Gαi-mediated) of cAMP production and β-arrestin recruitment. In contrast, it acts as an enhancer of agonist-induced ERK phosphorylation. Alone, the compound can act also as an allosteric agonist, increasing cAMP production and ERK phosphorylation. We find that in both saturation and kinetic-binding experiments, the Org 27569 and PSNCBAM-1 appeared to influence only orthosteric ligand maximum occupancy rather than affinity. The data indicate that the allosteric modulators share a common mechanism whereby they increase available high-affinity CB1 agonist binding sites. The receptor conformation stabilized by the allosterics appears to induce signaling and also selectively traffics orthosteric agonist signaling via the ERK phosphorylation pathway.

Cannabidiolic acid prevents vomiting in Suncus murinus and nausea‐induced behaviour in rats by enhancing 5‐HT1A receptor activation

To evaluate the ability of cannabidiolic acid (CBDA) to reduce nausea and vomiting and enhance 5‐HT1A receptor activation in animal models.

AM630 behaves as a protean ligand at the human cannabinoid CB2 receptor.

BACKGROUND AND PURPOSE We have investigated how pre‐incubating hCB2 CHO cells with the CB2 receptor antagonists/inverse agonists, AM630 and SR144528, affects how these and other ligands target hCB2 receptors in these cells or their membranes.

Structural and pharmacological analysis of O-2050, a putative neutral cannabinoid CB1 receptor antagonist

Rimonabant, the prototypic antagonist of cannabinoid CB(1) receptors, has been reported to have inverse agonist properties at higher concentrations, which may complicate its use as a tool for mechanistic evaluation of cannabinoid pharmacology. Consequently, recent synthesis efforts have concentrated on discovery of a neutral antagonist using a variety of structural templates. The purpose of this study was to evaluate the pharmacological properties of the putative neutral cannabinoid CB(1) receptor antagonist O-2050, a sulfonamide side chain analog of Δ(8)-tetrahydrocannabinol. O-2050 and related sulfonamide cannabinoids exhibited good affinity for both cannabinoid CB(1) and CB(2) receptors. While the other sulfonamide analogs produced cannabinoid agonist effects in vivo (e.g., activity suppression, antinociception, and hypothermia), O-2050 stimulated activity and was inactive in the other two tests. O-2050 also decreased food intake in mice, an effect that was reminiscent of that produced by rimonabant. Unlike rimonabant, however, O-2050 did not block the effects of cannabinoid agonists in vivo, even when administered i.c.v. In contrast, O-2050 antagonized the in vitro effects of cannabinoid agonists in [(35)S]GTPγS and mouse vas deferens assays without having activity on its own in either assay. Further evaluation revealed that O-2050 fully and dose-dependently substituted for Δ(9)-tetrahydrocannabinol in a mouse drug discrimination procedure (a cannabinoid agonist effect) and that it inhibited forskolin-stimulated cyclic AMP signaling with a maximum efficacy of approximately half that of the full agonist CP55,940 [(-)-cis-3-[2-hydroxy-4(1,1-dimethyl-heptyl)phenyl]-trans-4-(3-hydroxy-propyl)cyclohexanol]. Together, these results suggest that O-2050 is not a viable candidate for classification as a neutral cannabinoid CB(1) receptor antagonist.

Expression and function of the endocannabinoid system in glial cells.

In the last few years the role and significance of the glia in CNS function and pathology have been drastically reassessed. Glial cells physiology appears very different in healthy versus pathological brain and the recent identification of cannabinoid receptors and their endogenous ligands in glia has triggered a number of studies exploring the role of (endo)cannabinoid system in glia functionality and disease. (Endo)cannabinoids exert their effects in these cells directly affecting some important peculiar functions of the glia and actively promoting biochemical signals ending in a pro-survival fate for these cells. By contrast, (endo)cannabinoids induce a selective death in glia-derived tumor cells. Of special physiological and therapeutic relevance is the reported ability of glial cells during neuropathological conditions to release an increased amount of endocannabinoids and to overexpress cannabinoid receptors. This evidence has suggested that the endocannabinoids production by glial cells may constitute an endogenous defense mechanism preventing the propagation of neuroinflammation and cell damage. The present paper will review the evidence supporting the regulatory role of (endo)cannabinoids in glia function, holding in consideration their therapeutic potential as neuroprotective and/or anticancer agents.

In vitro and in vivo pharmacological characterization of two novel selective cannabinoid CB2 receptor inverse agonists

We have previously developed quinolone-3-carboxamides with the aim of obtaining new ligands for both cannabinoid receptors, CB1 and CB2. Our preliminary screening led to the identification of cannabinoid receptor ligands characterized by high affinity and, in some cases, also selectivity for CB(2) receptors. Specifically, three compounds, 1, 2 and 3 showed high affinity for CB2 as well as high selectivity over CB1 receptors. In addition, the activity shown by 1 against the formalin-induced nocifensive response in mice, reported in our previous paper, suggests that quinolone-3-carboxamides possess anti-nociceptive properties. In the present work, we have performed functional in vitro bioassays with the aim of investigating the functional activity in the [35S]GTPgammaS binding assay of the other two compounds that, like 1, behave as CB2 selective ligands, and their potential analgesic actions in vivo. We found that both 2 and 3 behave in vitro as CB2 inverse agonists and are able to decrease nociceptive behaviour in the late phase of the formalin test only at the highest dose tested, although, at lower doses, they prevent the anti-nociceptive effects of a selective CB2 partial agonist in the formalin test. These results identify in 2 and 3 two novel, potent and selective CB2 antagonists/inverse agonists and confirm previous reports in the literature that, in addition to agonists at cannabinoid CB2 receptors, also inverse agonists/antagonists at these receptors show promise as anti-inflammatory agents.

Investigations on the 4-Quinolone-3-Carboxylic Acid Motif Part 5: Modulation of the Physicochemical Profile of a Set of Potent and Selective Cannabinoid-2 Receptor Ligands through a Bioisosteric Approach†

Three heterocyclic systems were selected as potential bioisosteres of the amide linker for a series of 1,6‐disubstituted‐4‐quinolone‐3‐carboxamides, which are potent and selective CB2 ligands that exhibit poor water solubility, with the aim of improving their physicochemical profile and also of clarifying properties of importance for amide bond mimicry. Among the newly synthesized compounds, a 1,2,3‐triazole derivative (1‐(adamantan‐1‐yl)‐4‐[6‐(furan‐2‐yl)‐1,4‐dihydro‐4‐oxo‐1‐pentylquinolin‐3‐yl]‐1H‐1,2,3‐triazole) emerged as the most promising in terms of both physicochemical and pharmacodynamic properties. When assayed in vitro, this derivative exhibited inverse agonist activity, whereas, in the formalin test in mice, it produced analgesic effects antagonized by a well‐established inverse agonist. Metabolic studies allowed the identification of a side chain hydroxylated derivative as its only metabolite, which, in its racemic form, still showed appreciable CB2 selectivity, but was 150‐fold less potent than the parent compound.

Investigations on the 4-quinolone-3-carboxylic acid motif. 6. Synthesis and pharmacological evaluation of 7-substituted quinolone-3-carboxamide derivatives as high affinity ligands for cannabinoid receptors

Within our studies on structure-activity relationships of 4-quinolone-3-carboxamides as cannabinoid ligands, a new series of compounds characterized by a fluoro or phenylthio group at 7-position and different substituents at N1 and carboxamide nitrogen were synthesized and evaluated for their binding ability to cannabinoid type 1 (CB1) and type 2 (CB2) receptors. Most of the compounds showed affinity for one or both cannabinoid receptors at nanomolar concentration, with K(i)(CB1) and K(i)(CB2) values ranging from 2.45 to >10,000 nM and from 0.09 to 957 nM, respectively. The N-(3,4-dichlorobenzyl)amide derivatives 27 and 40 displayed relatively low affinity, but high selectivity towards the CB1 receptor. Compounds 4 and 40, a CB2 and a CB1 ligand, respectively, behaved as partial agonists in the [(35)S]GTPγS assay. They showed very low permeability through (MDCK-MDR1) cells and might, therefore, represent possible lead structures for further optimization in the search for cannabinoid ligands unable to cross the blood-brain barrier.