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Use of Cannabis, the most widely used illicit drug worldwide, is associated with acute anxiety, and anxiety disorders following regular use. The precise neural and receptor basis of these effects have not been tested in man. Employing a combination of functional MRI (fMRI) and positron emission tomography (PET), we investigated whether the effects of delta-9-tetrahydrocannabinol (delta-9-THC), the main psychoactive ingredient of cannabis, on anxiety and on amygdala response while processing fearful stimuli were related to local availability of its main central molecular target, cannabinoid-1 (CB1) receptors in man. Fourteen healthy males were studied with fMRI twice, one month apart, following an oral dose of either delta-9-THC (10 mg) or placebo, while they performed a fear-processing task. Baseline availability of the CB1 receptor was studied using PET with [ 11 C]MePPEP, a CB1 inverse agonist radioligand. Relative to the placebo condition, delta-9-THC induced anxiety and modulated right amygdala activation while processing fear. Both these effects were positively correlated with CB1 receptor availability in the right amygdala. These results suggest that the acute effects of cannabis on anxiety in males are mediated by the modulation of amygdalar function by delta-9-THC and the extent of these effects are related to local availability of CB1 receptors.

Delta-9-tetrahydrocannabinol (THC)/cannabidiol (CBD) [Sativex ® ] is an oromucosal spray formulation that contains principally THC and CBD at an approximately 1:1 fixed ratio, derived from cloned Cannabis sativa L. plants. The main active substance, THC, acts as a partial agonist at human cannabinoid receptors (CB 1 and CB 2 ), and thus, may modulate the effects of excitatory (glutamate) and inhibitory (gamma-aminobutyric acid) neurotransmitters. THC/CBD is approved in a number of countries, including Germany and the UK, as an add-on treatment for symptom improvement in adult patients with moderate to severe spasticity due to multiple sclerosis who have not responded adequately to other anti-spasticity medication and who demonstrate clinically significant improvement in spasticity-related symptoms during an initial trial of therapy. In the largest multinational clinical trial that evaluated the approved THC/CBD regimen in this population, 12 weeks’ double-blind treatment with THC/CBD significantly reduced spasticity severity (primary endpoint) compared with placebo in patients who achieved a clinically significant improvement in spasticity after 4 weeks’ single-blind THC/CBD treatment, as assessed by a patient-rated numerical rating scale. A significantly greater proportion of THC/CBD than placebo recipients achieved a ≥30 % reduction (a clinically relevant reduction) in spasticity severity. The efficacy of THC/CBD has been also shown in at least one everyday clinical practice study (MOVE 2). THC/CBD was generally well tolerated in clinical trials. Dizziness and fatigue were reported most frequently during the first 4 weeks of treatment and resolved within a few days even with continued treatment. Thus, add-on THC/CBD is a useful symptomatic treatment option for its approved indication.

Cannabinoids, derivatives of L., can activate the endocannabinoid system via two endogenous receptors, CB1 and CB2. This system is crucial in regulating folliculogenesis, fertility, and reproductive function. This study investigated the potential effects of cannabinoid agonists and antagonists on ovarian health and function in female mice. 80 NMRI mice were divided into 10 groups. Treatment groups received CB1 or CB2 agonists, antagonists, or their combinations for five days. The animals were then sacrificed, the ovaries were excised and weighed, and their volume was measured. Total RNA was extracted from the left ovary for qPCR analysis, while the right ovary was fixed in Bouin's solution for histological evaluation following H&E staining. Treatment with CB1/CB2 agonist+CB1 antagonist (W102+AM251) decreased the level of NAPE-PLD (a key factor in the production of endocannabinoids in cells) and increased the level of FAAH (responsible for cannabinoid degradation) genes compared to all groups. CB2 antagonist (AM630) increased the number of primary, preantral, and antral follicles, the volume and weight of ovaries, and estrogen levels. Meanwhile, the CB1 antagonist (AM251) significantly increased microvascular density in the ovaries. Cannabinoids modulate ovarian physiology and folliculogenesis, with CB2 receptors playing a particularly significant role. Antagonism at CB2 appeared to differentially affect cannabinoid-metabolizing enzymes in ovarian follicles and differentially affect their maturation. However, our preliminary novel findings in mice require human studies before clinical application.

The Cannabis sativa plant contains more than 120 cannabinoids. With the exceptions of ∆ 9 -tetrahydrocannabinol (∆ 9 -THC) and cannabidiol (CBD), comparatively little is known about the pharmacology of the less-abundant plant-derived (phyto) cannabinoids. The best-studied transducers of cannabinoid-dependent effects are type 1 and type 2 cannabinoid receptors (CB1R, CB2R). Partial agonism of CB1R by ∆ 9 -THC is known to bring about the ‘high’ associated with Cannabis use, as well as the pain-, appetite-, and anxiety-modulating effects that are potentially therapeutic . CB2R activation by certain cannabinoids has been associated with anti-inflammatory activities. We assessed the activity of 8 phytocannabinoids at human CB1R, and CB2R in Chinese hamster ovary (CHO) cells stably expressing these receptors and in C57BL/6 mice in an attempt to better understand their pharmacodynamics. Specifically, ∆ 9 -THC, ∆ 9 -tetrahydrocannabinolic acid (∆ 9 -THCa), ∆ 9 -tetrahydrocannabivarin (THCV), CBD, cannabidiolic acid (CBDa), cannabidivarin (CBDV), cannabigerol (CBG), and cannabichromene (CBC) were evaluated. Compounds were assessed for their affinity to receptors, ability to inhibit cAMP accumulation, βarrestin2 recruitment, receptor selectivity, and ligand bias in cell culture; and cataleptic, hypothermic, anti-nociceptive, hypolocomotive, and anxiolytic effects in mice. Our data reveal partial agonist activity for many phytocannabinoids tested at CB1R and/or CB2R, as well as in vivo responses often associated with activation of CB1R. These data build on the growing body of literature showing cannabinoid receptor-dependent pharmacology for these less-abundant phytocannabinoids and are critical in understanding the complex and interactive pharmacology of Cannabis -derived molecules.

Objective: To evaluate the efficacy, safety and tolerability of taranabant in obese and overweight patients. Design: Double-blind, randomized, placebo-controlled study. Subjects: Patients were ⩾18 years old, with body mass index of 27–43 kg m –2 , and 51% with metabolic syndrome (MS) randomized to placebo ( N =417) or taranabant 2 mg ( N =414), 4 mg ( N =415) or 6 mg ( N =1256) for 104 weeks. Measurements: Key efficacy measurements included body weight, waist circumference (WC), lipid and glycemic end points. Results: On the basis of risk/benefit assessments, the 6-mg dose was discontinued during year 1 (patients on 6 mg were down-dosed to 2 mg or placebo) and the 4-mg dose was discontinued during year 2 (patients on 4 mg were down-dosed to 2 mg). Changes from baseline in body weight at week 52 (all-patients-treated population, last observation carried forward analysis) were −2.6, −6.6 and −8.1 kg, respectively, for placebo and taranabant 2 and 4 mg (both doses P <0.001 vs placebo). For patients who completed year 1, changes from baseline in body weight at week 104 were −1.4, −6.4 and −7.6 kg for placebo and taranabant 2 and 4 mg, respectively (both doses P <0.001 vs placebo). The proportions of patients at weeks 52 and 104 who lost at least 5 and 10% of their baseline body weight were significantly higher and the proportions of patients who met criteria for MS were significantly lower for taranabant 2 and 4 mg vs placebo. The incidence of adverse experiences classified in the gastrointestinal, nervous, psychiatric, cutaneous and vascular organ systems were generally observed to be dose related with taranabant vs placebo. Conclusion: Taranabant at the 2- and 4-mg dose was effective in achieving clinically significant weight loss over 2 years and was associated with dose-related increases in adverse experiences. On the basis of these and other data, an assessment was made that the overall safety and efficacy profile of taranabant did not support its further development for the treatment of obesity.

Human tissues express cannabinoid CB1 and CB2 receptors that can be activated by endogenously released ‘endocannabinoids’ or exogenously administered compounds in a manner that reduces the symptoms or opposes the underlying causes of several disorders in need of effective therapy. Three medicines that activate cannabinoid CB1/CB2 receptors are now in the clinic: Cesamet (nabilone), Marinol (dronabinol; Δ9-tetrahydrocannabinol (Δ9-THC)) and Sativex (Δ9-THC with cannabidiol). These can be prescribed for the amelioration of chemotherapy-induced nausea and vomiting (Cesamet and Marinol), stimulation of appetite (Marinol) and symptomatic relief of cancer pain and/or management of neuropathic pain and spasticity in adults with multiple sclerosis (Sativex). This review mentions several possible additional therapeutic targets for cannabinoid receptor agonists. These include other kinds of pain, epilepsy, anxiety, depression, Parkinson's and Huntington's diseases, amyotrophic lateral sclerosis, stroke, cancer, drug dependence, glaucoma, autoimmune uveitis, osteoporosis, sepsis, and hepatic, renal, intestinal and cardiovascular disorders. It also describes potential strategies for improving the efficacy and/or benefit-to-risk ratio of these agonists in the clinic. These are strategies that involve (i) targeting cannabinoid receptors located outside the blood-brain barrier, (ii) targeting cannabinoid receptors expressed by a particular tissue, (iii) targeting upregulated cannabinoid receptors, (iv) selectively targeting cannabinoid CB2 receptors, and/or (v) adjunctive ‘multi-targeting’.

The cannabinoid receptor 1 (CB ) is the principal target of the psychoactive constituent of marijuana, the partial agonist Δ -tetrahydrocannabinol (Δ -THC). Here we report two agonist-bound crystal structures of human CB in complex with a tetrahydrocannabinol (AM11542) and a hexahydrocannabinol (AM841) at 2.80 Å and 2.95 Å resolution, respectively. The two CB -agonist complexes reveal important conformational changes in the overall structure, relative to the antagonist-bound state, including a 53% reduction in the volume of the ligand-binding pocket and an increase in the surface area of the G-protein-binding region. In addition, a 'twin toggle switch' of Phe200 and Trp356 (superscripts denote Ballesteros-Weinstein numbering) is experimentally observed and appears to be essential for receptor activation. The structures reveal important insights into the activation mechanism of CB and provide a molecular basis for predicting the binding modes of Δ -THC, and endogenous and synthetic cannabinoids. The plasticity of the binding pocket of CB seems to be a common feature among certain class A G-protein-coupled receptors. These findings should inspire the design of chemically diverse ligands with distinct pharmacological properties.

Inflammatory bowel disease (IBD) is a general term used to describe a group of chronic inflammatory conditions of the gastrointestinal tract of unknown etiology, including two primary forms: Crohn’s disease (CD) and ulcerative colitis (UC). The endocannabinoid system (ECS) plays an important role in modulating many physiological processes including intestinal homeostasis, modulation of gastrointestinal motility, visceral sensation, or immunomodulation of inflammation in IBD. It consists of cannabinoid receptors (CB1 and CB2), transporters for cellular uptake of endocannabinoid ligands, endogenous bioactive lipids (Anandamide and 2-arachidonoylglycerol), and the enzymes responsible for their synthesis and degradation (fatty acid amide hydrolase and monoacylglycerol lipase), the manipulation of which through agonists and antagonists of the system, shows a potential therapeutic role for ECS in inflammatory bowel disease. This review summarizes the role of ECS components on intestinal inflammation, suggesting the advantages of cannabinoid-based therapies in inflammatory bowel disease.

The endocannabinoid system was revealed following the understanding of the mechanism of action of marijuana's major psychotropic principle, Δ9-tetrahydrocannabinol, and includes two G-protein-coupled receptors (GPCRs; the cannabinoid CB1 and CB2 receptors), their endogenous ligands (the endocannabinoids, the best studied of which are anandamide and 2-arachidonoylglycerol (2-AG)), and the proteins that regulate the levels and activity of these receptors and ligands. However, other minor lipid metabolites different from, but chemically similar to, anandamide and 2-AG have also been suggested to act as endocannabinoids. Thus, unlike most other GPCRs, cannabinoid receptors appear to have more than one endogenous agonist, and it has been often wondered what could be the physiological meaning of this peculiarity. In 1999, it was proposed that anandamide might also activate other targets, and in particular the transient receptor potential of vanilloid type-1 (TRPV1) channels. Over the last decade, this interaction has been shown to occur both in peripheral tissues and brain, during both physiological and pathological conditions. TRPV1 channels can be activated also by another less abundant endocannabinoid, N-arachidonoyldopamine, but not by 2-AG, and have been proposed by some authors to act as ionotropic endocannabinoid receptors. This article will discuss the latest discoveries on this subject, and discuss, among others, how anandamide and 2-AG differential actions at TRPV1 and cannabinoid receptors contribute to making this signalling system a versatile tool available to organisms to fine-tune homeostasis.

Astrocytes take up glucose from the bloodstream to provide energy to the brain, thereby allowing neuronal activity and behavioural responses 1 – 5 . By contrast, astrocytes are under neuronal control through specific neurotransmitter receptors 5 – 7 . However, whether the activation of astroglial receptors can directly regulate cellular glucose metabolism to eventually modulate behavioural responses is unclear. Here we show that activation of mouse astroglial type-1 cannabinoid receptors associated with mitochondrial membranes (mtCB 1 ) hampers the metabolism of glucose and the production of lactate in the brain, resulting in altered neuronal functions and, in turn, impaired behavioural responses in social interaction assays. Specifically, activation of astroglial mtCB 1 receptors reduces the phosphorylation of the mitochondrial complex I subunit NDUFS4, which decreases the stability and activity of complex I. This leads to a reduction in the generation of reactive oxygen species by astrocytes and affects the glycolytic production of lactate through the hypoxia-inducible factor 1 pathway, eventually resulting in neuronal redox stress and impairment of behavioural responses in social interaction assays. Genetic and pharmacological correction of each of these effects abolishes the effect of cannabinoid treatment on the observed behaviour. These findings suggest that mtCB 1 receptor signalling can directly regulate astroglial glucose metabolism to fine-tune neuronal activity and behaviour in mice. In mice, persistent activation of mitochondrial cannabinoid receptors in astroglia impairs cellular glucose metabolism and lactate production, leading to an increase in redox stress in neurons and altered behavioural responses.