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Two cannabinoid receptors have been identified: [CB.sub,1], present in the central nervous system (CNS) and to a lesser extent in other tissues, and [CB.sub.2], present outside the CNS, in peripheral organs. There is evidence for the presence of [CB.sub.2]-like receptors in peripheral nerve terminals. We report now that we have synthesized a [CB.sub.2]-specific agonist, code-named HU-308. This cannabinoid does not bind to [CB.sub.1] ([K.sub.i] [is greater than] 10/[micro]M), but does so efficiently to [CB.sub.2] ([K.sub.i] = 22.7 [+ or -] 3.9 nM); it inhibits forskolin-stimulated cyclic AMP production in [CB.sub.2]-transfected cells, but does so much less in [CB.sub,1]-transfected cells. HU-308 shows no activity in mice in a tetrad of behavioral tests, which together have been shown to be specific for tetrahydrocannabinol (THC)-type activity in the CNS mediated by [CB.sub,1]. However, HU-308 reduces blood pressure, blocks defecation, and elicits anti-inflammatory and peripheral analgesic activity. The hypotension, the inhibition of defecation, the anti-inflammatory and peripheral analgesic effects produced by HU-308 are blocked (or partially blocked) by the [CB.sub.2] antagonist SR-144528, but not by the [CB.sub.1] antagonist SR-141716A. These results demonstrate the feasibility of discovering novel nonpsychotropic cannabinoids that may lead to new therapies for hypertension, inflammation, and pain.

Background and Purpose Epilepsy is the most prevalent neurological disease and is characterized by recurrent seizures. Here, we investigate (i) the anticonvulsant profiles of cannabis-derived botanical drug substances ( BDSs) rich in cannabidivarin ( CBDV) and containing cannabidiol ( CBD) in acute in vivo seizure models and (ii) the binding of CBDV BDSs and their components at cannabinoid CB1 receptors. Experimental Approach The anticonvulsant profiles of two CBDV BDSs (50-422 mg·kg−1) were evaluated in three animal models of acute seizure. Purified CBDV and CBD were also evaluated in an isobolographic study to evaluate potential pharmacological interactions. CBDV BDS effects on motor function were also investigated using static beam and grip strength assays. Binding of CBDV BDSs to cannabinoid CB1 receptors was evaluated using displacement binding assays. Key Results CBDV BDSs exerted significant anticonvulsant effects in the pentylenetetrazole (≥100 mg·kg−1) and audiogenic seizure models (≥87 mg·kg−1), and suppressed pilocarpine-induced convulsions (≥100 mg·kg−1). The isobolographic study revealed that the anticonvulsant effects of purified CBDV and CBD were linearly additive when co-administered. Some motor effects of CBDV BDSs were observed on static beam performance; no effects on grip strength were found. The Δ9-tetrahydrocannabinol and Δ9-tetrahydrocannabivarin content of CBDV BDS accounted for its greater affinity for CB1 cannabinoid receptors than purified CBDV. Conclusions and Implications CBDV BDSs exerted significant anticonvulsant effects in three models of seizure that were not mediated by the CB1 cannabinoid receptor and were of comparable efficacy with purified CBDV. These findings strongly support the further clinical development of CBDV BDSs for the treatment of epilepsy. [ABSTRACT FROM AUTHOR]

Background and Purpose: To evaluate the ability of cannabidiolic acid (CBDA) to reduce nausea and vomiting and enhance 5-HT(1A) receptor activation in animal models.Experimental Approach: We investigated the effect of CBDA on (i) lithium chloride (LiCl)-induced conditioned gaping to a flavour (nausea-induced behaviour) or a context (model of anticipatory nausea) in rats; (ii) saccharin palatability in rats; (iii) motion-, LiCl- or cisplatin-induced vomiting in house musk shrews (Suncus murinus); and (iv) rat brainstem 5-HT(1A) receptor activation by 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and mouse whole brain CB(1) receptor activation by CP55940, using [³⁵S]GTPγS-binding assays.Key Results: In shrews, CBDA (0.1 and/or 0.5 mg·kg⁻¹ i.p.) reduced toxin- and motion-induced vomiting, and increased the onset latency of the first motion-induced emetic episode. In rats, CBDA (0.01 and 0.1 mg·kg⁻¹ i.p.) suppressed LiCl- and context-induced conditioned gaping, effects that were blocked by the 5-HT(1A) receptor antagonist, WAY100635 (0.1 mg·kg⁻¹ i.p.), and, at 0.01 mg·kg⁻¹ i.p., enhanced saccharin palatability. CBDA-induced suppression of LiCl-induced conditioned gaping was unaffected by the CB₁ receptor antagonist, SR141716A (1 mg·kg⁻¹ i.p.). In vitro, CBDA (0.1-100 nM) increased the E(max) of 8-OH-DPAT.Conclusions and Implications: Compared with cannabidiol, CBDA displays significantly greater potency at inhibiting vomiting in shrews and nausea in rats, and at enhancing 5-HT(1A) receptor activation, an action that accounts for its ability to attenuate conditioned gaping in rats. Consequently, CBDA shows promise as a treatment for nausea and vomiting, including anticipatory nausea for which no specific therapy is currently available. [ABSTRACT FROM AUTHOR]

Background and Purpose: To evaluate the hypothesis that activation of somatodendritic 5-HT(1A) 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.Experimental Approach: The potential of systemic and intra-DRN administration of 5-HT(1A) receptor antagonists, WAY100135 or WAY100635, to prevent the anti-emetic effect of CBD in shrews (Suncus murinus) and the anti-nausea-like effects of CBD (conditioned gaping) in rats were evaluated. Also, the ability of intra-DRN administration of CBD to produce anti-nausea-like effects (and reversal by systemic WAY100635) was assessed. In vitro studies evaluated the potential of CBD to directly target 5-HT(1A) receptors and to modify the ability of the 5-HT(1A) agonist, 8-OH-DPAT, to stimulate [(35) S]GTPγS binding in rat brainstem membranes.Key Results: CBD suppressed nicotine-, lithium chloride (LiCl)- and cisplatin (20 mg·kg(-1) , but not 40 mg·kg(-1) )-induced vomiting in the S. murinus and LiCl-induced conditioned gaping in rats. Anti-emetic and anti-nausea-like effects of CBD were suppressed by WAY100135 and the latter by WAY100635. When administered to the DRN: (i) WAY100635 reversed anti-nausea-like effects of systemic CBD, and (ii) CBD suppressed nausea-like effects, an effect that was reversed by systemic WAY100635. CBD also displayed significant potency (in a bell-shaped dose-response curve) at enhancing the ability of 8-OH-DPAT to stimulate [(35) S]GTPγS binding to rat brainstem membranes in vitro. Systemically administered CBD and 8-OH-DPAT synergistically suppressed LiCl-induced conditioned gaping.Conclusions and Implications: These results suggest that CBD produced its anti-emetic/anti-nausea effects by indirect activation of the somatodendritic 5-HT(1A) autoreceptors in the DRN.Linked Articles: This article is part of a themed section on Cannabinoids in Biology and Medicine. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-8. To view Part I of Cannabinoids in Biology and Medicine visit http://dx.doi.org/10.1111/bph.2011.163.issue-7. [ABSTRACT FROM AUTHOR]

Background and Purpose: Cannabis is taken as self-medication by patients with inflammatory bowel disease for symptomatic relief. Cannabinoid receptor agonists decrease inflammation in animal models of colitis, but their effects on the disturbed motility is not known. (-)-Cannabidiol (CBD) has been shown to interact with Delta(9)-tetrahydrocannabinol (THC) in behavioural studies, but it remains to be established if these cannabinoids interact in vivo in inflammatory disorders. Therefore the effects of CBD and THC alone and in combination were investigated in a model of colitis.Experimental Approach: The 2,4,6-trinitrobenzene sulphonic acid (TNBS) model of acute colitis in rats was used to assess damage, inflammation (myeloperoxidase activity) and in vitro colonic motility. Sulphasalazine was used as an active control drug.Key Results: Sulphasalazine, THC and CBD proved beneficial in this model of colitis with the dose-response relationship for the phytocannabinoids showing a bell-shaped pattern on the majority of parameters (optimal THC and CBD dose, 10 mg.kg(-1)). THC was the most effective drug. The effects of these phytocannabinoids were additive, and CBD increased some effects of an ineffective THC dose to the level of an effective one. THC alone and in combination with CBD protected cholinergic nerves whereas sulphasalazine did not.Conclusions and Implications: In this model of colitis, THC and CBD not only reduced inflammation but also lowered the occurrence of functional disturbances. Moreover the combination of CBD and THC could be beneficial therapeutically, via additive or potentiating effects. [ABSTRACT FROM AUTHOR]

Background and Purpose: Cannabis is the source of at least seventy phytocannabinoids. The pharmacology of most of these has been little investigated, three notable exceptions being Delta(9)-tetrahydrocannabinol, cannabidiol and Delta(9)-tetrahydrocannabivarin. This investigation addressed the question of whether the little-studied phytocannabinoid, cannabigerol, can activate or block any G protein-coupled receptor.Experimental Approach: The [(35)S]GTPgammaS binding assay, performed with mouse brain membranes, was used to test the ability of cannabigerol to produce G protein-coupled receptor activation or blockade. Its ability to displace [(3)H]CP55940 from mouse CB(1) and human CB(2) cannabinoid receptors and to inhibit electrically evoked contractions of the mouse isolated vas deferens was also investigated.Key Results: In the brain membrane experiments, cannabigerol behaved as a potent alpha(2)-adrenoceptor agonist (EC(50)= 0.2 nM) and antagonized the 5-HT(1A) receptor agonist, R-(+)-8-hydroxy-2-(di-n-propylamino)tetralin (apparent K(B)= 51.9 nM). At 10 microM, it also behaved as a CB(1) receptor competitive antagonist. Additionally, cannabigerol inhibited evoked contractions of the vas deferens in a manner that appeared to be alpha(2)-adrenoceptor-mediated (EC(50)= 72.8 nM) and displayed significant affinity for mouse CB(1) and human CB(2) receptors.Conclusions and Implications: This investigation has provided the first evidence that cannabigerol can activate alpha(2)-adrenoceptors, bind to cannabinoid CB(1) and CB(2) receptors and block CB(1) and 5-HT(1A) receptors. It will now be important to investigate why cannabigerol produced signs of agonism more potently in the [(35)S]GTPgammaS binding assay than in the vas deferens and also whether it can inhibit noradrenaline uptake in this isolated tissue and in the brain. [ABSTRACT FROM AUTHOR]

Cannabis sativa is the source of a unique set of compounds known collectively as plant cannabinoids or phytocannabinoids. This review focuses on the manner with which three of these compounds, (−)-trans-Δ9-tetrahydrocannabinol (Δ9-THC), (−)-cannabidiol (CBD) and (−)-trans-Δ9-tetrahydrocannabivarin (Δ9-THCV), interact with cannabinoid CB1 and CB2 receptors. Δ9-THC, the main psychotropic constituent of cannabis, is a CB1 and CB2 receptor partial agonist and in line with classical pharmacology, the responses it elicits appear to be strongly influenced both by the expression level and signalling efficiency of cannabinoid receptors and by ongoing endogenous cannabinoid release. CBD displays unexpectedly high potency as an antagonist of CB1/CB2 receptor agonists in CB1- and CB2-expressing cells or tissues, the manner with which it interacts with CB2 receptors providing a possible explanation for its ability to inhibit evoked immune cell migration. Δ9-THCV behaves as a potent CB2 receptor partial agonist in vitro. In contrast, it antagonizes cannabinoid receptor agonists in CB1-expressing tissues. This it does with relatively high potency and in a manner that is both tissue and ligand dependent. Δ9-THCV also interacts with CB1 receptors when administered in vivo, behaving either as a CB1 antagonist or, at higher doses, as a CB1 receptor agonist. Brief mention is also made in this review, first of the production by Δ9-THC of pharmacodynamic tolerance, second of current knowledge about the extent to which Δ9-THC, CBD and Δ9-THCV interact with pharmacological targets other than CB1 or CB2 receptors, and third of actual and potential therapeutic applications for each of these cannabinoids.British Journal of Pharmacology (2008) 153, 199–215; doi:10.1038/sj.bjp.0707442; published online 10 September 2007 [ABSTRACT FROM AUTHOR]

Background and Purpose: To follow up in vitro evidence that Delta(9)-tetrahydrocannabivarin extracted from cannabis (eDelta(9)-THCV) is a CB(1) receptor antagonist by establishing whether synthetic Delta(9)-tetrahydrocannabivarin (O-4394) and Delta(8)-tetrahydrocannabivarin (O-4395) behave as CB(1) antagonists in vivo.Experimental Approach: O-4394 and O-4395 were compared with eDelta(9)-THCV as displacers of [(3)H]-CP55940 from specific CB(1) binding sites on mouse brain membranes and as antagonists of CP55940 in [(35)S]GTPgammaS binding assays performed with mouse brain membranes and of R-(+)-WIN55212 in mouse isolated vasa deferentia. Their ability to antagonize in vivo effects of 3 or 10 mg kg(-1) (i.v.) Delta(9)-tetrahydrocannabinol in mice was then investigated.Key Results: O-4394 and O-4395 exhibited similar potencies to eDelta(9)-THCV as displacers of [(3)H]-CP55940 (K (i)=46.6 and 64.4 nM, respectively) and as antagonists of CP55940 in the [(35)S]GTPgammaS binding assay (apparent K (B)=82.1 and 125.9 nM, respectively) and R-(+)-WIN55212 in the vas deferens (apparent K (B)=4.8 and 3.9 nM respectively). At i.v. doses of 0.1, 0.3, 1.0 and/or 3 mg kg(-1) O-4394 and O-4395 attenuated Delta(9)-tetrahydrocannabinol-induced anti-nociception (tail-flick test) and hypothermia (rectal temperature). O-4395 but not O-4394 also antagonized Delta(9)-tetrahydrocannabinol-induced ring immobility. By themselves, O-4395 and O-4394 induced ring immobility at 3 or 10 mg kg(-1) (i.v.) and antinociception at doses above 10 mg kg(-1) (i.v.). O-4395 also induced hypothermia at 3 mg kg(-1) (i.v.) and above.Conclusions and Implications: O-4394 and O-4395 exhibit similar in vitro potencies to eDelta(9)-THCV as CB(1) receptor ligands and as antagonists of cannabinoid receptor agonists and can antagonize Delta(9)-tetrahydrocannabinol in vivo. [ABSTRACT FROM AUTHOR]

Background and purpose:To follow up in vitro evidence that Δ9-tetrahydrocannabivarin extracted from cannabis (eΔ9-THCV) is a CB1 receptor antagonist by establishing whether synthetic Δ9-tetrahydrocannabivarin (O-4394) and Δ8-tetrahydrocannabivarin (O-4395) behave as CB1 antagonists in vivo.Experimental approach:O-4394 and O-4395 were compared with eΔ9-THCV as displacers of [3H]-CP55940 from specific CB1 binding sites on mouse brain membranes and as antagonists of CP55940 in [35S]GTPγS binding assays performed with mouse brain membranes and of R-(+)-WIN55212 in mouse isolated vasa deferentia. Their ability to antagonize in vivo effects of 3 or 10 mg kg−1 (i.v.) Δ9-tetrahydrocannabinol in mice was then investigated.Key results:O-4394 and O-4395 exhibited similar potencies to eΔ9-THCV as displacers of [3H]-CP55940 (K i=46.6 and 64.4 nM, respectively) and as antagonists of CP55940 in the [35S]GTPγS binding assay (apparent K B=82.1 and 125.9 nM, respectively) and R-(+)-WIN55212 in the vas deferens (apparent K B=4.8 and 3.9 nM respectively). At i.v. doses of 0.1, 0.3, 1.0 and/or 3 mg kg−1 O-4394 and O-4395 attenuated Δ9-tetrahydrocannabinol-induced anti-nociception (tail-flick test) and hypothermia (rectal temperature). O-4395 but not O-4394 also antagonized Δ9-tetrahydrocannabinol-induced ring immobility. By themselves, O-4395 and O-4394 induced ring immobility at 3 or 10 mg kg−1 (i.v.) and antinociception at doses above 10 mg kg−1 (i.v.). O-4395 also induced hypothermia at 3 mg kg−1 (i.v.) and above.Conclusions and implications:O-4394 and O-4395 exhibit similar in vitro potencies to eΔ9-THCV as CB1 receptor ligands and as antagonists of cannabinoid receptor agonists and can antagonize Δ9-tetrahydrocannabinol in vivo.British Journal of Pharmacology (2007) 150, 586–594. doi:10.1038/sj.bjp.0707124; published online 22 January 2007 [ABSTRACT FROM AUTHOR]