Explore the vast range of titles available.

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.

Combining patch-clamp recordings and subsequent STORM imaging of individual cells, the authors show that the axon terminals of perisomatically- and dendritically-projecting GABAergic interneurons show differences in CB 1 receptor number, active zone complexity, and receptor:effector ratio. Chronic exposure to THC evoked a dose-dependent and long-lasting downregulation of CB 1 at these synapses. A major challenge in neuroscience is to determine the nanoscale position and quantity of signaling molecules in a cell type– and subcellular compartment–specific manner. We developed a new approach to this problem by combining cell-specific physiological and anatomical characterization with super-resolution imaging and studied the molecular and structural parameters shaping the physiological properties of synaptic endocannabinoid signaling in the mouse hippocampus. We found that axon terminals of perisomatically projecting GABAergic interneurons possessed increased CB 1 receptor number, active-zone complexity and receptor/effector ratio compared with dendritically projecting interneurons, consistent with higher efficiency of cannabinoid signaling at somatic versus dendritic synapses. Furthermore, chronic Δ 9 -tetrahydrocannabinol administration, which reduces cannabinoid efficacy on GABA release, evoked marked CB 1 downregulation in a dose-dependent manner. Full receptor recovery required several weeks after the cessation of Δ 9 -tetrahydrocannabinol treatment. These findings indicate that cell type–specific nanoscale analysis of endogenous protein distribution is possible in brain circuits and identify previously unknown molecular properties controlling endocannabinoid signaling and cannabis-induced cognitive dysfunction.

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.

Neural stem cells (NSCs) are self-renewing cells that can differentiate into multiple neural lineages and repopulate regions of the brain after injury. We have investigated the role of endocannabinoids (eCBs), endogenous cues that modulate neuronal functions including neurogenesis, and their receptors CB(1) and CB(2) in mouse NSCs. Real-time PCR and Western blot analyses indicated that CB(1) is present at higher levels than CB(2) in NSCs. The eCB anandamide (AEA) or the CB(1)-specific agonist ACEA enhanced NSC differentiation into neurons, but not astrocytes and oligodendrocytes, whereas the CB(2)-specific agonist JWH133 was ineffective. Conversely, the effect of AEA was inhibited by CB(1), but not CB(2), antagonist, corroborating the specificity of the response. CB(1) activation also enhanced maturation of neurons, as indicated by morphometric analysis of neurites. CB(1) stimulation caused long-term inhibition of the ERK1/2 pathway. Consistently, pharmacological inhibition of the ERK1/2 pathway recapitulated the effects exerted by CB(1) activation on neuronal differentiation and maturation. Lastly, gene array profiling showed that CB(1) activation augmented the expression of genes involved in neuronal differentiation while decreasing that of stemness genes. These results highlight the role of CB(1) in the regulation of NSC fate and suggest that its activation may represent a pro-neuronal differentiation signal.

Obesity is characterized by chronic low-grade, systemic inflammation, altered gut microbiota, and gut barrier disruption. Additionally, obesity is associated with increased activity of endocannabinoid system (eCB). However, the clear connection between gut microbiota and the eCB system in the regulation of energy homeostasis and adipose tissue inflammation and metabolism, remains to be established. We investigated the effect of treatment of mice with a cannabinoid receptor 1 (CB1) antagonist on Diet-Induced Obesity (DIO), specifically whether such a treatment that blocks endocannabinoid activity can induce changes in gut microbiota and anti-inflammatory state in adipose tissue. Blockade of CB1 attenuated DIO, inflammatory cytokines and trafficking of M1 macrophages into adipose tissue. Decreased inflammatory tone was associated with a lower intestinal permeability and decreased metabolic endotoxemia as evidenced by reduced plasma LPS level, and improved hyperglycemia and insulin resistance. 16S rRNA metagenomics sequencing revealed that CB1 blockade dramatically increased relative abundance of Akkermansia muciniphila and decreased Lanchnospiraceae and Erysipelotrichaceae in the gut. Together, the current study suggests that blocking of CB1 ameliorates Diet-Induced Obesity and metabolic disorder by modulating macrophage inflammatory mediators, and that this effect is associated with alterations in gut microbiota and their metabolites.

Rationale The endocannabinoid neurotransmitter, anandamide, has been implicated in the central modulation of stress responses. Previous animal experiments have shown that inhibitors of the anandamide-degrading enzyme, fatty acid amide hydrolase (FAAH), enhance the ability to cope with acute and chronic stress. Objectives Here, we investigated the effects of the globally active FAAH inhibitor URB597 in a rat model of predator stress-induced long-term anxiety. Results Rats exposed to 2,5-dihydro-2,4,5-trimethylthiazoline (TMT), a chemical constituent of fox feces, developed a persistent anxiety-like state, which was assessed 7 days after exposure using the elevated plus maze (EPM) test. Systemic administration of URB597 [0.03–0.1-0.3 mg/kg, intraperitoneal (ip)] 2 h before testing suppressed TMT-induced behaviors with a median effective dose (IC 50 ) of 0.075 mg/kg. This effect was strongly correlated with inhibition of brain FAAH activity ( r 2  = 1.0) and was accompanied by increased brain levels of three FAAH substrates: the endocannabinoid anandamide and the endogenous peroxisome proliferator-activated receptor-α (PPAR-α) agonists, oleoylethanolamide (OEA), and palmitoylethanolamide (PEA). The anxiolytic-like effects of URB597 were blocked by co-administration of the CB 1 receptor antagonist rimonabant (1 mg/kg, ip), but not of the PPAR-α antagonist GW6471 (1 mg/kg, ip). Finally, when administered 18 h after TMT exposure (i.e., 6 days before the EPM test), URB597 (0.3 mg/kg, ip) prevented the consolidation of anxiety-like behavior in a CB 1 -dependent manner. Conclusions The results support the hypothesis that anandamide-mediated signaling at CB 1 receptors serves an important regulatory function in the stress response, and confirm that FAAH inhibition may offer a potential therapeutic strategy for post-traumatic stress disorder.

G-protein-coupled receptors (GPCRs) play important roles in cellular functions. However, their intracellular organization is largely unknown. Through investigation of the cannabinoid receptor 1 (CB 1 ), we discovered periodically repeating clusters of CB 1 hotspots within the axons of neurons. We observed these CB 1 hotspots interact with the membrane-associated periodic skeleton (MPS) forming a complex crucial in the regulation of CB 1 signaling. Furthermore, we found that CB 1 hotspot periodicity increased upon CB 1 agonist application, and these activated CB 1 displayed less dynamic movement compared to non-activated CB 1 . Our results suggest that CB 1 forms periodic hotspots organized by the MPS as a mechanism to increase signaling efficacy upon activation. Despite the importance of G-protein-coupled receptors in many cellular functions, their intracellular organisation is largely unknown. The authors identified periodically repeating clusters of cannabinoid receptor 1 hotspots within neuronal axons that are dynamically regulated by CB 1 agonists.

Cannabinoids affect CB 1 receptors on the mitochondrial membranes in the brain, triggering a decrease in downstream cAMP-dependent signalling; this leads to a decrease in brain mitochondrial activity and to cannabinoid-induced amnesia. Bioenergetics deficiency and memory The pathological effect of chronic mitochondrial dysfunction on cognitive function is well established, however the acute modulation of neural processing by mitochondrial signalling is less well understood. These authors demonstrate that acute functional disruption of the brain by cannabinoids involves the activation and signalling from mitochondrial cannabinoid receptors. Thus, even acute mitochondrial bioenergetic changes or disruption can have a short-term effect on cognition, underscoring the role that mitochondria have in regulating normal brain activity. Cellular activity in the brain depends on the high energetic support provided by mitochondria, the cell organelles which use energy sources to generate ATP 1 , 2 , 3 , 4 . Acute cannabinoid intoxication induces amnesia in humans and animals 5 , 6 , and the activation of type-1 cannabinoid receptors present at brain mitochondria membranes (mtCB 1 ) can directly alter mitochondrial energetic activity 7 , 8 , 9 . Although the pathological impact of chronic mitochondrial dysfunctions in the brain is well established 1 , 2 , the involvement of acute modulation of mitochondrial activity in high brain functions, including learning and memory, is unknown. Here, we show that acute cannabinoid-induced memory impairment in mice requires activation of hippocampal mtCB 1 receptors. Genetic exclusion of CB 1 receptors from hippocampal mitochondria prevents cannabinoid-induced reduction of mitochondrial mobility, synaptic transmission and memory formation. mtCB 1 receptors signal through intra-mitochondrial Gα i protein activation and consequent inhibition of soluble-adenylyl cyclase (sAC). The resulting inhibition of protein kinase A (PKA)-dependent phosphorylation of specific subunits of the mitochondrial electron transport system eventually leads to decreased cellular respiration. Hippocampal inhibition of sAC activity or manipulation of intra-mitochondrial PKA signalling or phosphorylation of the Complex I subunit NDUFS2 inhibit bioenergetic and amnesic effects of cannabinoids. Thus, the G protein-coupled mtCB 1 receptors regulate memory processes via modulation of mitochondrial energy metabolism. By directly linking mitochondrial activity to memory formation, these data reveal that bioenergetic processes are primary acute regulators of cognitive functions.

The generation of functional regulatory T cells (Tregs) is essential to keep tissue homeostasis and restore healthy immune responses in many biological and inflammatory contexts. Cannabinoids have been pointed out as potential therapeutic tools for several diseases. Dendritic cells (DCs) express the endocannabinoid system, including the cannabinoid receptors CB1 and CB2. However, how cannabinoids might regulate functional properties of DCs is not completely understood. We uncover that the triggering of cannabinoid receptors promote human tolerogenic DCs that are able to prime functional FOXP3+ Tregs in the context of different inflammatory diseases. Mechanistically, cannabinoids imprint tolerogenicity in human DCs by inhibiting NF-κB, MAPK and mTOR signalling pathways while inducing AMPK and functional autophagy flux via CB1- and PPARα-mediated activation, which drives metabolic rewiring towards increased mitochondrial activity and oxidative phosphorylation. Cannabinoids exhibit in vivo protective and anti-inflammatory effects in LPS-induced sepsis and also promote the generation of FOXP3+ Tregs. In addition, immediate anaphylactic reactions are decreased in peanut allergic mice and the generation of allergen-specific FOXP3+ Tregs are promoted, demonstrating that these immunomodulatory effects take place in both type 1- and type 2-mediated inflammatory diseases. Our findings might open new avenues for novel cannabinoid-based interventions in different inflammatory and immune-mediated diseases.

The CB1 receptor mediates the central nervous system response to cannabinoids, and is a drug target for pain, anxiety and seizures. CB1 also responds to allosteric modulators, which influence cannabinoid binding and efficacy. To understand the mechanism of these compounds, we solved the crystal structure of CB1 with the negative allosteric modulator (NAM) ORG27569 and the agonist CP55940. The structure reveals that the NAM binds to an extrahelical site within the inner leaflet of the membrane, which overlaps with a conserved site of cholesterol interaction in many G protein-coupled receptors (GPCRs). The ternary structure with ORG27569 and CP55940 captures an intermediate state of the receptor, in which aromatic residues at the base of the agonist-binding pocket adopt an inactive conformation despite the large contraction of the orthosteric pocket. The structure illustrates a potential strategy for drug modulation of CB1 and other class A GPCRs. A crystal structure of the GPCR target of endocannabinoid signaling lipids and drugs, CB1, bound to a negative allosteric modulator (NAM) and an agonist, shows that the NAM binds to a membrane-embedded site reminiscent of the binding site of cholesterol.