The proposed mechanisms of action of CBD in epilepsy.

Highly purified cannabidiol (CBD) (approved as Epidiolex® in the United States and as EPIDYOLEX from the EU agency) has demonstrated efficacy with an acceptable safety profile in patients with Lennox-Gastaut or Dravet syndrome in four randomized controlled trials. While the mechanism of action of CBD underlying the reduction of seizures in humans is unknown, CBD possesses affinity for multiple targets, across a range of target classes, resulting in functional modulation of neuronal excitability, relevant to the pathophysiology of many disease types, including epilepsy. Here we present the pharmacological data supporting the role of three such targets, namely Transient receptor potential vanilloid-1 (TRPV1), the orphan G protein-coupled receptor-55 (GPR55) and the equilibrative nucleoside transporter 1 (ENT-1).

Chemotherapy-induced cachexia dysregulates hypothalamic and systemic lipoamines and is attenuated by cannabigerol.

BACKGROUND: Muscle wasting, anorexia, and metabolic dysregulation are common side-effects of cytotoxic chemotherapy, having a dose-limiting effect on treatment efficacy, and compromising quality of life and mortality. Extracts of Cannabis sativa, and analogues of the major phytocannabinoid Δ9-tetrahydrocannabinol, have been used to ameliorate chemotherapy-induced appetite loss and nausea for decades. However, psychoactive side-effects limit their clinical utility, and they have little efficacy against weight loss. We recently established that the non-psychoactive phytocannabinoid cannabigerol (CBG) stimulates appetite in healthy rats, without neuromotor side-effects. The present study assessed whether CBG attenuates anorexia and/or other cachectic effects induced by the broad-spectrum chemotherapy agent cisplatin. METHODS: An acute cachectic phenotype was induced in adult male Lister-hooded rats by 6 mg/kg (i.p.) cisplatin. In total 66 rats were randomly allocated to groups receiving vehicle only, cisplatin only, or cisplatin and 60 or 120 mg/kg CBG (po, b.i.d.). Feeding behavior, bodyweight and locomotor activity were recorded for 72 hours, at which point rats were sacrificed for post-mortem analyses. Myofibre atrophy, protein synthesis and autophagy dysregulation were assessed in skeletal muscle, plasma metabolic profiles were obtained by untargeted 1H-NMR metabonomics, and levels of endocannabinoid-like lipoamines quantified in plasma and hypothalami by targeted HPLC-MS/MS lipidomics. RESULTS: CBG (120 mg/kg) modestly increased food intake, predominantly at 36-60hrs (p<0.05), and robustly attenuated cisplatin-induced weight loss from 6.3% to 2.6% at 72hrs (p<0.01). Cisplatin-induced skeletal muscle atrophy was associated with elevated plasma corticosterone (3.7 vs 13.1ng/ml, p<0.01), observed selectively in MHC type IIx (p<0.05) and IIb (p<0.0005) fibres, and was reversed by pharmacological rescue of dysregulated Akt/S6-mediated protein synthesis and autophagy processes. Plasma metabonomic analysis revealed cisplatin administration produced a wide-ranging aberrant metabolic phenotype (Q2Y=0.5380, p=0.001), involving alterations to glucose, amino acid, choline and lipid metabolism, citrate cycle, gut microbiome function, and nephrotoxicity, which were partially normalized by CBG treatment (Q2Y=0.2345, p=0.01). Lipidomic analysis of hypothalami and plasma revealed extensive cisplatin-induced dysregulation of central and peripheral lipoamines (29/79 and 11/26 screened, respectively), including reversible elevations in systemic N-acyl glycine concentrations which were negatively associated with the anti-cachectic effects of CBG treatment. CONCLUSIONS: Endocannabinoid-like lipoamines may have hitherto unrecognized roles in the metabolic side-effects associated with chemotherapy, with the N-acyl glycine subfamily in particular identified as a potential therapeutic target and/or biomarker of anabolic interventions. CBG-based treatments may represent a novel therapeutic option for chemotherapy-induced cachexia, warranting investigation in tumour-bearing cachexia models.

Cannabidiol modulates phosphorylated rpS6 signalling in a zebrafish model of Tuberous Sclerosis Complex.

Tuberous sclerosis complex (TSC) is a rare disease caused by mutations in the TSC1 or TSC2 genes and is characterized by widespread tumour growth, intractable epilepsy, cognitive deficits and autistic behaviour. CBD has been reported to decrease seizures and inhibit tumour cell progression, therefore we sought to determine the influence of CBD on TSC pathology in zebrafish carrying a nonsense mutation in the tsc2 gene. CBD treatment from 6 to 7 days post-fertilization (dpf) induced significant anxiolytic actions without causing sedation. Furthermore, CBD treatment from 3 dpf had no impact on tsc2-/- larvae motility nor their survival. CBD treatment did, however, reduce the number of phosphorylated rpS6 positive cells, and their cross-sectional cell size. This suggests a CBD mediated suppression of mechanistic target of rapamycin (mTOR) activity in the tsc2-/- larval brain. Taken together, these data suggest that CBD selectively modulates levels of phosphorylated rpS6 in the brain and additionally provides an anxiolytic effect. This is pertinent given the alterations in mTOR signalling in experimental models of TSC. Additional work is necessary to identify upstream signal modulation and to further justify the use of CBD as a possible therapeutic strategy to manage TSC.

mTOR-related neuropathology in mutant tsc2 zebrafish: Phenotypic, transcriptomic and pharmacological analysis.

Tuberous sclerosis complex (TSC) is a rare, genetic disease caused by loss-of-function mutations in either TSC1 or TSC2. Patients with TSC are neurologically characterized by the presence of abnormal brain structure, intractable epilepsy and TSC-associated neuropsychiatric disorders. Given the lack of effective long-term treatments for TSC, there is a need to gain greater insight into TSC-related pathophysiology and to identify and develop new treatments. In this work we show that homozygous tsc2-/- mutant zebrafish larvae, but not tsc2+/- and WT larvae, display enlarged brains, reduced locomotor behavior and epileptiform discharges at 7dpf. In addition, we pharmacologically validated the TSC model by demonstrating the dramatic rescue effect of pericardially injected rapamycin, a well-known mTOR inhibitor, on selected behavioral read-outs and at the molecular level. By means of trancriptome profiling we also acquired more insight into the neuropathology of TSC, and as a result were able to highlight possible new treatment targets. The gene expression profiles of WT and tsc2+/- larvae revealed 117 differentially expressed genes (DEGs), while between WT and tsc2-/- larvae and tsc2+/- and tsc2-/- larvae there were 1414 and 1079 DEGs, respectively. Pathway enrichment analysis from the WT and tsc2-/- DEGs, identified 14 enriched pathways from the up-regulated genes and 6 enriched pathways from the down-regulated genes. Moreover, genes related to inflammation and immune response were up-regulated in the heads of tsc2-/- larvae, in line with the findings in human brain tissue where inflammatory and immune responses appear to be major hallmarks of TSC. Taken together, our phenotypic, transcriptomic and pharmacological analysis identified the tsc2-/- zebrafish as a preclinical model that mirrors well aspects of the human condition and delineated relevant TSC-related biological pathways. The model may be of value for future TSC-related drug discovery and development programs.

A cannabigerol-rich Cannabis sativa extract, devoid of [INCREMENT]9-tetrahydrocannabinol, elicits hyperphagia in rats.

Nonpsychoactive phytocannabinoids (pCBs) from Cannabis sativa may represent novel therapeutic options for cachexia because of their pleiotropic pharmacological activities, including appetite stimulation. We have recently shown that purified cannabigerol (CBG) is a novel appetite stimulant in rats. As standardized extracts from Cannabis chemotypes dominant in one pCB [botanical drug substances (BDSs)] often show greater efficacy and/or potency than purified pCBs, we investigated the effects of a CBG-rich BDS, devoid of psychoactive [INCREMENT]-tetrahydrocannabinol, on feeding behaviour. Following a 2 h prefeed satiation procedure, 16 male Lister-hooded rats were administered CBG-BDS (at 30-240 mg/kg) or vehicle. Food intake, meal pattern microstructure and locomotor activity were recorded over 2 h. The total food intake was increased by 120 and 240 mg/kg CBG-BDS (1.53 and 1.36 g, respectively, vs. 0.56 g in vehicle-treated animals). Latency to feeding onset was dose dependently decreased at all doses, and 120 and 240 mg/kg doses increased both the number of meals consumed and the cumulative size of the first two meals. No significant effect was observed on ambulatory activity or rearing behaviour. CBG-BDS is a novel appetite stimulant, which may have greater potency than purified CBG, despite the absence of [INCREMENT]-tetrahydrocannabinol in the extract.

Cannabigerol is a novel, well-tolerated appetite stimulant in pre-satiated rats.

RATIONALE: The appetite-stimulating properties of cannabis are well documented and have been predominantly attributed to the hyperphagic activity of the psychoactive phytocannabinoid, ∆(9)-tetrahydrocannabinol (∆(9)-THC). However, we have previously shown that a cannabis extract devoid of ∆(9)-THC still stimulates appetite, indicating that other phytocannabinoids also elicit hyperphagia. One possible candidate is the non-psychoactive phytocannabinoid cannabigerol (CBG), which has affinity for several molecular targets with known involvement in the regulation of feeding behaviour. OBJECTIVES: The objective of the study was to assess the effects of CBG on food intake and feeding pattern microstructure. METHODS: Male Lister hooded rats were administered CBG (30-120 mg/kg, per ora (p.o.)) or placebo and assessed in open field, static beam and grip strength tests to determine a neuromotor tolerability profile for this cannabinoid. Subsequently, CBG (at 30-240 mg/kg, p.o.) or placebo was administered to a further group of pre-satiated rats, and hourly intake and meal pattern data were recorded over 2 h. RESULTS: CBG produced no adverse effects on any parameter in the neuromotor tolerability test battery. In the feeding assay, 120-240 mg/kg CBG more than doubled total food intake and increased the number of meals consumed, and at 240 mg/kg reduced latency to feed. However, the sizes or durations of individual meals were not significantly increased. CONCLUSIONS: Here, we demonstrate for the first time that CBG elicits hyperphagia, by reducing latency to feed and increasing meal frequency, without producing negative neuromotor side effects. Investigation of the therapeutic potential of CBG for conditions such as cachexia and other disorders of eating and body weight regulation is thus warranted.

Nuclear accumulation of myocyte muscle LIM protein is regulated by heme oxygenase 1 and correlates with cardiac function in the transition to failure.

KEY POINTS: The present study investigated the mechanism associated with impaired cardiac mechanosensing that leads to heart failure by examining the factors regulating muscle LIM protein subcellular distribution in myocytes. In myocytes, muscle LIM protein subcellular distribution is regulated by cell contractility rather than passive stretch via heme oxygenase-1 and histone deacetylase signalling. The result of the present study provide new insights into mechanotransduction in cardiac myocytes. Myocyte mechanosensitivity, as indicated by the muscle LIM protein ratio, is also correlated with cardiac function in the transition to failure in a guinea-pig model of disease. This shows that the loss mechanosensitivity plays an important role during the transition to failure in the heart. The present study provides the first indication that mechanosensing could be modified pharmacologically during the transition to heart failure. ABSTRACT: Impaired mechanosensing leads to heart failure and a decreased ratio of cytoplasmic to nuclear CSRP3/muscle LIM protein (MLP ratio) is associated with a loss of mechanosensitivity. In the present study, we tested whether passive or active stress/strain was important in modulating the MLP ratio and determined whether this correlated with heart function during the transition to failure. We exposed cultured neonatal rat myocytes to a 10% cyclic mechanical stretch at 1 Hz, or electrically paced myocytes at 6.8 V (1 Hz) for 48 h. The MLP ratio decreased by 50% (P < 0.05, n = 4) only in response to electrical pacing, suggesting impaired mechanosensitivity. Inhibition of contractility with 10 µm blebbistatin resulted in an ∼3-fold increase in the MLP ratio (n = 8, P < 0.05), indicating that myocyte contractility regulates nuclear MLP. Inhibition of histone deacetylase (HDAC) signalling with trichostatin A increased nuclear MLP following passive stretch, suggesting that HDACs block MLP nuclear accumulation. Inhibition of heme oxygenase1 (HO-1) activity with protoporphyrin IX zinc(II) blocked MLP nuclear accumulation. To examine how mechanosensitivity changes during the transition to heart failure, we studied a guinea-pig model of angiotensin II infusion (400 ng kg(-1)  min(-1) ) over 12 weeks. Using subcellular fractionation, we showed that the MLP ratio increased by 88% (n = 4, P < 0.01) during compensated hypertrophy but decreased significantly during heart failure (P < 0.001, n = 4). The MLP ratio correlated significantly with the E/A ratio (r = 0.71, P < 0.01, n = 12), a clinical measure of diastolic function. These data indicate for the first time that myocyte mechanosensitivity as indicated by the MLP ratio is regulated primarily by myocyte contractility via HO-1 and HDAC signalling.

Voltage-gated sodium (NaV) channel blockade by plant cannabinoids does not confer anticonvulsant effects per se.

Cannabidiol (CBD) is a non-psychoactive, well-tolerated, anticonvulsant plant cannabinoid, although its mechanism(s) of seizure suppression remains unknown. Here, we investigate the effect of CBD and the structurally similar cannabinoid, cannabigerol (CBG), on voltage-gated Na(+) (NaV) channels, a common anti-epileptic drug target. CBG's anticonvulsant potential was also assessed in vivo. CBD effects on NaV channels were investigated using patch-clamp recordings from rat CA1 hippocampal neurons in brain slices, human SH-SY5Y (neuroblastoma) cells and mouse cortical neurons in culture. CBG effects were also assessed in SH-SY5Y cells and mouse cortical neurons. CBD and CBG effects on veratridine-stimulated human recombinant NaV1.1, 1.2 or 1.5 channels were assessed using a membrane potential-sensitive fluorescent dye high-throughput assay. The effect of CBG on pentyleneterazole-induced (PTZ) seizures was assessed in rat. CBD (10µM) blocked NaV currents in SH-SY5Y cells, mouse cortical neurons and recombinant cell lines, and affected spike parameters in rat CA1 neurons; CBD also significantly decreased membrane resistance. CBG blocked NaV to a similar degree to CBD in both SH-SY5Y and mouse recordings, but had no effect (50-200mg/kg) on PTZ-induced seizures in rat. CBD and CBG are NaV channel blockers at micromolar concentrations in human and murine neurons and recombinant cells. In contrast to previous reports investigating CBD, CBG had no effect upon PTZ-induced seizures in rat, indicating that NaV blockade per se does not correlate with anticonvulsant effects.

Endogenous cholinergic tone modulates spontaneous network level neuronal activity in primary cortical cultures grown on multi-electrode arrays.

BACKGROUND: Cortical cultures grown long-term on multi-electrode arrays (MEAs) are frequently and extensively used as models of cortical networks in studies of neuronal firing activity, neuropharmacology, toxicology and mechanisms underlying synaptic plasticity. However, in contrast to the predominantly asynchronous neuronal firing activity exhibited by intact cortex, electrophysiological activity of mature cortical cultures is dominated by spontaneous epileptiform-like global burst events which hinders their effective use in network-level studies, particularly for neurally-controlled animat ('artificial animal') applications. Thus, the identification of culture features that can be exploited to produce neuronal activity more representative of that seen in vivo could increase the utility and relevance of studies that employ these preparations. Acetylcholine has a recognised neuromodulatory role affecting excitability, rhythmicity, plasticity and information flow in vivo although its endogenous production by cortical cultures and subsequent functional influence upon neuronal excitability remains unknown. RESULTS: Consequently, using MEA electrophysiological recording supported by immunohistochemical and RT-qPCR methods, we demonstrate for the first time, the presence of intrinsic cholinergic neurons and significant, endogenous cholinergic tone in cortical cultures with a characterisation of the muscarinic and nicotinic components that underlie modulation of spontaneous neuronal activity. We found that tonic muscarinic ACh receptor (mAChR) activation affects global excitability and burst event regularity in a culture age-dependent manner whilst, in contrast, tonic nicotinic ACh receptor (nAChR) activation can modulate burst duration and the proportion of spikes occurring within bursts in a spatio-temporal fashion. CONCLUSIONS: We suggest that the presence of significant endogenous cholinergic tone in cortical cultures and the comparability of its modulatory effects to those seen in intact brain tissues support emerging, exploitable commonalities between in vivo and in vitro preparations. We conclude that experimental manipulation of endogenous cholinergic tone could offer a novel opportunity to improve the use of cortical cultures for studies of network-level mechanisms in a manner that remains largely consistent with its functional role.

A low-Δ9 tetrahydrocannabinol cannabis extract induces hyperphagia in rats.

Appetite stimulation via partial agonism of cannabinoid type 1 receptors by Δtetrahydrocannabinol (ΔTHC) is well documented and can be modulated by non-ΔTHC phytocannabinoids. ΔTHC concentrations sufficient to elicit hyperphagia induce changes to both appetitive (reduced latency to feed) and consummatory (increased meal one size and duration) behaviours. Here, we show that a cannabis extract containing too little ΔTHC to stimulate appetite can induce hyperphagia solely by increasing appetitive behaviours. Twelve, male Lister hooded rats were presatiated before treatment with a low-ΔTHC cannabis extract (0.5, 1.0, 2.0 and 4.0 mg/kg). Hourly intake and meal pattern data were recorded and analyzed using one-way analyses of variance followed by Bonferroni post-hoc tests. The cannabis extract significantly increased food intake during the first hour of testing (at 4.0 mg/kg) and significantly reduced the latency to feed versus vehicle treatments (at doses ≥1.0 mg/kg). Meal size and duration were unaffected. These results show only the increase in appetitive behaviours, which could be attributed to non-ΔTHC phytocannabinoids in the extract rather than ΔTHC. Although further study is required to determine the constituents responsible for these effects, these results support the presence of non-ΔTHC cannabis constituent(s) that exert a stimulatory effect on appetite and likely lack the detrimental psychoactive effects of ΔTHC.

Cannabis constituents modulate δ9-tetrahydrocannabinol-induced hyperphagia in rats.

RATIONALE: The hyperphagic effect of Delta9-tetrahydrocannabinol (Delta9THC) in humans and rodents is well known. However, no studies have investigated the importance of Delta9THC composition and any influence other non-Delta9THC cannabinoids present in Cannabis sativa may have. We therefore compared the effects of purified Delta9THC, synthetic Delta9THC (dronabinol), and Delta9THC botanical drug substance (Delta9THC-BDS), a Delta9THC-rich standardized extract comparable in composition to recreationally used cannabis. METHODS: Adult male rats were orally dosed with purified Delta9THC, synthetic Delta9THC, or Delta9THC-BDS, matched for Delta9THC content (0.34-2.68 mg/kg). Prior to dosing, subjects were satiated, and food intake was recorded following Delta9THC administration. Data were then analyzed in terms of hourly intake and meal patterns. RESULTS: All three Delta9THC substances tested induced significant hyperphagic effects at doses >or=0.67 mg/kg. These effects included increased intake during hour one, a shorter latency to onset of feeding and a greater duration and consumption in the first meal. However, while some differences in vehicle control intakes were observed, there were significant, albeit subtle, differences in pattern of effects between the purified Delta9THC and Delta9THC-BDS. CONCLUSION: All Delta9THC compounds displayed classical Delta9THC effects on feeding, significantly increasing shortterm intake whilst decreasing latency to the first meal. We propose that the subtle adjustment to the meal patterns seen between the purified Delta9THC and Delta9THC-BDS are due to non-Delta9THC cannabinoids present in Delta9THC-BDS. These compounds and other non-cannabinoids have an emerging and diverse pharmacology and can modulate Delta9THC-induced hyperphagia, making them worth further investigation for their therapeutic potential.

Cholinergic modulation of intrinsic fibre-evoked excitatory transmission contains a nicotinic component in immature but not adult rat piriform cortex, in vitro.

The piriform cortex (PC) is highly prone to epileptogenesis, particularly in immature animals, where decreased muscarinic modulation of PC intrinsic fibre excitatory neurotransmission is implicated as a likely cause. However, whether higher levels of acetylcholine (ACh) release occur in immature vs. adult PC remains unclear. We investigated this using in vitro extracellular electrophysiological recording techniques. Intrinsic fibre-evoked extracellular field potentials (EFPs) were recorded from layers II to III in PC brain slices prepared from immature (P14-18) and adult (P>40) rats. Adult and immature PC EFPs were suppressed by eserine (1 microM) or neostigmine (1 microM) application, with a greater suppression in immature (approximately 40%) than adult (approximately 30%) slices. Subsequent application of atropine (1 microM) reversed EFP suppression, producing supranormal (approximately 12%) recovery in adult slices, suggesting that suppression was solely muscarinic ACh receptor-mediated and that some 'basal' cholinergic 'tone' was present. Conversely, atropine only partially reversed anticholinesterase effects in immature slices, suggesting the presence of additional non-muscarinic modulation. Accordingly, nicotine (50 microM) caused immature field suppression (approximately 30%) that was further enhanced by neostigmine, whereas it had no effect on adult EFPs. Unlike atropine, nicotinic antagonists, mecamylamine and methyllycaconitine, induced immature supranormal field recovery (approximately 20%) following anticholinesterase-induced suppression (with no effect on adult slices), confirming that basal cholinergic 'tone' was also present. We suggest that nicotinic inhibitory cholinergic modulation occurs in the immature rat PC intrinsic excitatory fibre system, possibly to complement the existing, weak muscarinic modulation, and could be another important developmentally regulated system governing immature PC susceptibility towards epileptogenesis.