Cannabidiol improves survival and behavioural co-morbidities of Dravet syndrome in mice

Cannabidiol attenuates seizure susceptibility and behavioural deficits in adult CDKL5R59X knock-in mice

Cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder (CDD) is caused by a loss-of-function mutation in CDKL5 gene, encoding a serine-threonine kinase highly expressed in the brain. CDD manifests with early-onset epilepsy, autism, motor impairment and severe intellectual disability. While there are no known treatments for CDD, the use of cannabidiol has recently been introduced into clinical practice for neurodevelopmental disorders. Given the increased clinical utilization of cannabidiol, we examined its efficacy in the CDKL5R59X knock-in (R59X) mice, a CDD model based on a human mutation that exhibits both lifelong seizure susceptibility and behavioural deficits. We found that cannabidiol pre-treatment rescued the increased seizure susceptibility in response to the chemoconvulsant pentylenetetrazol (PTZ), attenuated working memory and long-term memory impairments, and rescued social deficits in adult R59X mice. To elucidate a potential mechanism, we compared the developmental hippocampal and cortical expression of common endocannabinoid (eCB) targets in R59X mice and their wild-type littermates, including cannabinoid type 1 receptor (CB1R), transient receptor potential vanilloid type 1 (TRPV1) and 2 (TRPV2), G-coupled protein receptor 55 (GPR55) and adenosine receptor 1 (A1R). Many of these eCB targets were developmentally regulated in both R59X and wild-type mice. In addition, adult R59X mice demonstrated significantly decreased expression of CB1R and TRPV1 in the hippocampus, and TRPV2 in the cortex, while TRPV1 was increased in the cortex. These findings support the potential for dysregulation of eCB signalling as a plausible mechanism and therapeutic target in CDD, given the efficacy of cannabidiol to attenuate hyperexcitability and behavioural deficits in this disorder.

Cannabidiol is a behavioral modulator in BTBR mouse model of idiopathic autism

Introduction

The prevalence of Autism Spectrum Disorder (ASD) has drastically risen over the last two decades and is currently estimated to affect 1 in 36 children in the U.S., according to the center for disease control (CDC). This heterogenous neurodevelopmental disorder is characterized by impaired social interactions, communication deficits, and repetitive behaviors plus restricted interest. Autistic individuals also commonly present with a myriad of comorbidities, such as attention deficit hyperactivity disorder, anxiety, and seizures. To date, a pharmacological intervention for the treatment of core autistic symptoms has not been identified. Cannabidiol (CBD), the major nonpsychoactive constituent of Cannabis sativa, is suggested to have multiple therapeutic applications, but its effect(s) on idiopathic autism is unknown. We hypothesized that CBD will effectively attenuate the autism-like behaviors and autism-associated comorbid behaviors in BTBR T+Itpr3tf/J (BTBR) mice, an established mouse model of idiopathic ASD.

Methods

Male BTBR mice were injected intraperitoneally with either vehicle, 20 mg/kg CBD or 50 mg/kg CBD daily for two weeks beginning at postnatal day 21 ± 3. On the final treatment day, a battery of behavioral assays were used to evaluate the effects of CBD on the BTBR mice, as compared to age-matched, vehicle-treated C57BL/6 J mice.

Results

High dose (50 mg/kg) CBD treatment attenuated the elevated repetitive self-grooming behavior and hyperlocomotion in BTBR mice. The social deficits exhibited by the control BTBR mice were rescued by the 20 mg/kg CBD treatment.

Discussion

Our data indicate that different doses for CBD are needed for treating specific ASD-like behaviors. Together, our results suggest that CBD may be an effective drug to ameliorate repetitive/restricted behaviors, social deficits, and autism-associated hyperactivity.

Cannabidiol and positive effects on object recognition memory in an in vivo model of Fragile X Syndrome: Obligatory role of hippocampal GPR55 receptors

Cannabidiol (CBD), a non-psychotomimetic constituent of Cannabis sativa, has been recently approved for epileptic syndromes often associated with Autism spectrum disorder (ASD). However, the putative efficacy and mechanism of action of CBD in patients suffering from ASD and related comorbidities remain debated, especially because of the complex pharmacology of CBD. We used pharmacological, immunohistochemical and biochemical approaches to investigate the effects and mechanisms of action of CBD in the recently validated Fmr1-Δexon 8 rat model of ASD, that is also a model of Fragile X Syndrome (FXS), the leading monogenic cause of autism. CBD rescued the cognitive deficits displayed by juvenile Fmr1-Δexon 8 animals, without inducing tolerance after repeated administration. Blockade of CA1 hippocampal GPR55 receptors prevented the beneficial effect of both CBD and the fatty acid amide hydrolase (FAAH) inhibitor URB597 in the short-term recognition memory deficits displayed by Fmr1-Δexon 8 rats. Thus, CBD may exert its beneficial effects through CA1 hippocampal GPR55 receptors. Docking analysis further confirmed that the mechanism of action of CBD might involve competition for brain fatty acid binding proteins (FABPs) that deliver anandamide and related bioactive lipids to their catabolic enzyme FAAH. These findings demonstrate that CBD reduced cognitive deficits in a rat model of FXS and provide initial mechanistic insights into its therapeutic potential in neurodevelopmental disorders.

Effects of the Acute and Chronic Administration of Cannabidiol on Cognition in Humans and Animals: A Systematic Review

Introduction: The effects of cannabidiol (CBD) on cognition has been investigated in recent years to determine the therapeutic potential of this cannabinoid for a broad gamut of medical conditions, including neuropsychiatric disorders. The aim of the present study was to perform a systematic review of studies that analyzed the effects of the acute and chronic administration of CBD on cognition in humans and animals both to assess the cognitive safety of CBD and to determine a beneficial potential of CBD on cognition. Methods: The PubMed, Web of Science, PsycINFO, and Scopus databases were searched in December of 2022 for relevant articles using the following combinations of keywords: ("cannabidiol" OR "CBD") AND ("cognition" OR "processing cognitive" OR "memory" OR "language" OR "attention" OR "executive function" OR "social cognition" OR "perceptual motor ability" OR "processing speed"). Results: Fifty-nine articles were included in the present review (36 preclinical and 23 clinical trials). CBD seems not to have any negative effect on cognitive processing in rats. The clinical trials confirmed these findings in humans. One study found that repeated dosing with CBD may improve cognitive in people who use cannabis heavily but not individuals with neuropsychiatric disorders. Considering the context of neuropsychiatric disorders in animal models, CBD seems to reverse the harm caused by the experimental paradigms, such that the performance of these animals becomes similar to that of control animals. Conclusions: The results demonstrate that the chronic and acute administration of CBD seems not to impair cognition in humans without neuropsychiatric disorders. In addition, preclinical studies report promising results regarding the effects of CBD on the cognitive processing of animals. Future double-blind, placebo-controlled, randomized clinical trials with larger, less selective samples, with standardized tests, and using different doses of CBD in outpatients are of particular interest to elucidate the cognitive effects of CBD.

Informing the Cannabis Conjecture: From Life's Beginnings to Mitochondria, Membranes and the Electrome-A Review

Before the late 1980s, ideas around how the lipophilic phytocannabinoids might be working involved membranes and bioenergetics as these disciplines were "in vogue". However, as interest in genetics and pharmacology grew, interest in mitochondria (and membranes) waned. The discovery of the cognate receptor for tetrahydrocannabinol (THC) led to the classification of the endocannabinoid system (ECS) and the conjecture that phytocannabinoids might be "working" through this system. However, the how and the "why" they might be beneficial, especially for compounds like CBD, remains unclear. Given the centrality of membranes and mitochondria in complex organisms, and their evolutionary heritage from the beginnings of life, revisiting phytocannabinoid action in this light could be enlightening. For example, life can be described as a self-organising and replicating far from equilibrium dissipating system, which is defined by the movement of charge across a membrane. Hence the building evidence, at least in animals, that THC and CBD modulate mitochondrial function could be highly informative. In this paper, we offer a unique perspective to the question, why and how do compounds like CBD potentially work as medicines in so many different conditions? The answer, we suggest, is that they can modulate membrane fluidity in a number of ways and thus dissipation and engender homeostasis, particularly under stress. To understand this, we need to embrace origins of life theories, the role of mitochondria in plants and explanations of disease and ageing from an adaptive thermodynamic perspective, as well as quantum mechanics.

Disease-modifying effects of cannabidiol, β-caryophyllene and their combination in Syn1-Cre/Scn1aWT/A1783V mice, a preclinical model of Dravet syndrome

Cannabidiol (CBD) has been recently approved as an antiseizure agent in Dravet Syndrome (DS), a pediatric epileptic encephalopathy, but CBD could also be active against associated comorbidities. Such associated comorbidities were also attenuated by the sesquiterpene β-caryophyllene (BCP). Here, we have compared the efficacy of both compounds and further initiated the analysis of a possible additive effect between both compounds in relation with these comorbidities using two experimental approaches. The first experiment was aimed at comparing the benefits of CBD and BCP, including their combination in conditional knock-in Scn1a-A1783V mice, an experimental model of DS, treated since the postnatal day 10th to 24th. As expected, DS mice showed impairment in limb clasping, delay in the appearance of hindlimb grasp reflex and additional behavioural disturbances (e.g., hyperactivity, cognitive deterioration, social interaction deficits). This behavioural impairment was associated with marked astroglial and microglial reactivities in the prefrontal cortex and the hippocampal dentate gyrus. BCP and CBD administered alone were both able to partially attenuate the behavioural disturbances and the glial reactivities, with apparently greater efficacy against glial reactivities obtained with BCP, whereas superior effects in a few specific parameters were obtained when both compounds were combined. In the second experiment, we investigated this additive effect in cultured BV2 cells treated with BCP and/or CBD and stimulated with LPS. As expected, addition of LPS induced a marked increase in several inflammation-related markers (e.g., TLR4, COX-2, iNOS, catalase, TNF-α, IL-1β), as well as elevated Iba-1 immunostaining. Treatment with BCP or CBD attenuated these elevations, but, again and in general, superior results were obtained when both cannabinoids were combined. In conclusion, our results support the interest to continue investigating the combination of BCP and CBD to improve the therapeutic management of DS in relation with their disease-modifying properties.

Acute cannabidiol treatment enhances social interaction in adult male mice

Cannabidiol (CBD) is a non-intoxicating phytochemical from Cannabis sativa that is increasingly used to manage pain. The potential for CBD to ameliorate dimensional behavior symptoms occurring in multiple psychiatric disorders was suggested, including social interaction impairments. To test this hypothesis, adult male BTBRT+Itpr3tf/J (BTBR) mice, a model of idiopathic autism exhibiting social preference deficits and restrictive repetitive behaviors, were acutely treated with vehicle or 0.1, 1, or 10 mg/kg CBD. Social interaction preference was assessed 50 min after treatment, followed by social novelty preference at 60 min, marble burying at 75 min and social dominance at 120 min. CBD (10 mg/kg) enhanced BTBR social interaction but not social novelty preference, marble burying or dominance, with serum levels = 29 ± 11 ng/mg at 3 h post-injection. Next, acute 10 mg/kg CBD was compared to vehicle treatment in male serotonin transporter (SERT) knock-out mice, since SERT deficiency is an autism risk factor, and in their wildtype background strain controls C57BL/6J mice. CBD treatment generally enhanced social interaction preference and attenuated social novelty preference, yet neither marble burying nor dominance was affected. These findings show acute treatment with as little as 10 mg/kg purified CBD can enhance social interaction preference in male mice that are otherwise socially deficient.

Icariside II preconditioning evokes robust neuroprotection against ischaemic stroke, by targeting Nrf2 and the OXPHOS/NF-κB/ferroptosis pathway

BACKGROUND AND PURPOSE

Astrocytic nuclear factor erythroid-derived 2-related factor 2 (Nrf2) is a potential therapeutic target of ischaemic preconditioning (IPC). Icariside II (ICS II) is a naturally occurring flavonoid derived from Herba Epimedii with Nrf2 induction potency. This study was designed to clarify if exposure to ICS II mimicks IPC neuroprotection and if Nrf2 from astrocytes contributes to ICS II preconditioning against ischaemic stroke.

EXPERIMENTAL APPROACH

Mice with transient middle cerebral artery occlusion (MCAO)-induced focal cerebral ischaemia and primary astrocytes challenged with oxygen-glucose deprivation (OGD) were used to explore the neuroprotective effect of ICS II preconditioning. Additionally, Nrf2-deficient mice were pretreated with ICS II to determine whether ICS II exerts its neuroprotection by activating Nrf2.

KEY RESULTS

ICS II pretreatment mitigated cerebral injury in the mouse model of ischaemic stroke along with improving long-term recovery. Furthermore, proteomics screening identified Nrf2 as a crucial gene evoked by ICS II treatment and required for the anti-oxidative effect and anti-inflammatory effect of ICS II. Also, ICS II directly bound to Nrf2 and reinforced the transcriptional activity of Nrf2 after MCAO. Moreover, ICS II pretreatment exerted cytoprotective effects on astrocyte cultures following lethal OGD exposure, by promoting Nrf2 nuclear translocation and activating the OXPHOS/NF-κB/ferroptosis axis, while neuroprotection was decreased in Nrf2-deficient mice and Nrf2 siRNA blocked effects of ICS II.

CONCLUSION AND IMPLICATIONS

ICS II preconditioning provides robust neuroprotection against ischaemic stroke via the astrocytic Nrf2-mediated OXPHOS/NF-κB/ferroptosis axis. Thus, ICS II could be a promising Nrf2 activator to treat ischaemic stroke.

Cannabidiol attenuates generalized tonic-clonic and suppresses limbic seizures in the genetically epilepsy-prone rats (GEPR-3) strain

BACKGROUND

Cannabidiol (CBD) has been of rapidly growing interest in the epilepsy research field due to its antiseizure properties in preclinical models and patients with pharmacoresistant epilepsy. However, little is known about CBD effects in genetic models of epilepsies. Here we assessed CBD dose-response effects in the Genetically Epilepsy Prone Rats (GEPR-3) strain, which exhibits two types of epileptic seizures, brainstem-dependent generalized tonic-clonic seizures and limbic seizures.

METHODS

GEPR-3 s were submitted to the audiogenic seizure (AGS) protocol. Acute AGS are brainstem-dependent generalized tonic-clonic, while repeated AGS (or audiogenic kindling, AK), an epileptogenic process, leads to increased AGS severity and limbic seizure expression. Therefore, two different dose-response studies were performed, one for generalized tonic-clonic seizures and the other for limbic seizures. CBD time-course effects were assessed 2, 4, and 6 h after drug injection. GEPR-3 s were submitted to within-subject tests, receiving intraperitoneal injections of CBD (1, 10, 50, 100 mg/kg/ml) and vehicle.

RESULTS

CBD dose-dependently attenuated generalized tonic-clonic seizures in GEPR-3 s; CBD 50 and 100 mg/kg reduced brainstem-dependent seizure severity and duration. In fully kindled GEPR-3 s, CBD 10 mg/kg reduced limbic seizure severity and suppressed limbic seizure expression in 75% of animals.

CONCLUSIONS

CBD was effective against brainstem and limbic seizures in the GEPR-3 s. These results support the use of CBD treatment for epilepsies by adding new information about the pharmacological efficacy of CBD in suppressing inherited seizure susceptibility in the GEPR-3 s.

Cannabidiol reveals a disruptive strategy for 21st century epilepsy drug discovery

Over 30 antiseizure medicines (ASMs) have been uncovered in a diversity of preclinical seizure and epilepsy models, with several critical inflection points in the 20th century fundamentally transforming ASM discovery. This commentary aims to review the historical relevance of cannabidiol's (CBD; Epidiolex) approval for epilepsy in the context of other ASMs brought to market. Further, we highlight how CBD's approval may represent an inflection point for 21st century ASM discovery. CBD is one of the main phytocannabinoids of Cannabis sativa. Unlike its related phytocannabinoid, Δ9-tetrahydrocannabinol, CBD does not exert any euphorigenic, tolerance, or withdrawal effects at anticonvulsant doses. CBD also possess marked anti-inflammatory effects, offering the tantalizing potential of a new pharmacological approach in epilepsy. For decades, hints of the anticonvulsant profile of CBD had been suggested with a small handful of studies in rodent seizure models, yet difficulties in formulation, compounded by the social and regulatory pressures related to medical use of cannabis plant-derived agents constrained any clinical implementation. Nonetheless, CBD possesses a broad antiseizure profile in preclinical seizure and epilepsy models, but the transformative impact of CBD'-s approval came because of studies in a rodent model of the orphan disease Dravet syndrome (DS). DS is a pediatric developmental epileptic encephalopathy with high mortality, frequent spontaneous recurrent seizures, and marked resistance to conventional ASMs, such as phenytoin and carbamazepine. CBD was approved for DS by the US Food and Drug Administration in 2018 after convincing efficacy was established in randomized, placebo-controlled trials in children. Because of the clinical approval of CBD as a novel, cannabis plantderived ASM for DS, CBD has revealed a new strategy in ASM discovery to reignite 21st century therapeutic development for epilepsy. In this commentary, we review the major preclinical and clinical milestones of the late 20th century that made CBD, a compound historically subjected to regulatory restrictions, a key driver of a new discovery strategy for epilepsy in the 21st century.

Heat-induced seizures, premature mortality, and hyperactivity in a novel Scn1a nonsense model for Dravet syndrome

Dravet syndrome (Dravet) is a severe congenital developmental genetic epilepsy caused by de novo mutations in the SCN1A gene. Nonsense mutations are found in ∼20% of the patients, and the R613X mutation was identified in multiple patients. Here we characterized the epileptic and non-epileptic phenotypes of a novel preclinical Dravet mouse model harboring the R613X nonsense Scn1a mutation. Scn1a^WT/R613X mice, on a mixed C57BL/6J:129S1/SvImJ background, exhibited spontaneous seizures, susceptibility to heat-induced seizures, and premature mortality, recapitulating the core epileptic phenotypes of Dravet. In addition, these mice, available as an open-access model, demonstrated increased locomotor activity in the open-field test, modeling some non-epileptic Dravet-associated phenotypes. Conversely, Scn1a^WT/R613X mice, on the pure 129S1/SvImJ background, had a normal life span and were easy to breed. Homozygous Scn1a^R613X/R613X mice (pure 129S1/SvImJ background) died before P16. Our molecular analyses of hippocampal and cortical expression demonstrated that the premature stop codon induced by the R613X mutation reduced Scn1a mRNA and Na_V1.1 protein levels to ∼50% in heterozygous Scn1a^WT/R613X mice (on either genetic background), with marginal expression in homozygous Scn1a^R613X/R613X mice. Together, we introduce a novel Dravet model carrying the R613X Scn1a nonsense mutation that can be used to study the molecular and neuronal basis of Dravet, as well as the development of new therapies associated with SCN1A nonsense mutations in Dravet.

The effects of preventative cannabidiol in a male neuregulin 1 mouse model of schizophrenia

Cannabidiol (CBD) is a non-intoxicating cannabinoid with antipsychotic-like properties, however it’s potential to prevent schizophrenia development has not been thoroughly investigated. Brain maturation during adolescence creates a window where CBD could potentially limit the development of schizophrenia. The neuregulin 1 transmembrane domain heterozygous (Nrg1 TM HET) mutant mouse shows face, predictive, and construct validity for schizophrenia. Here we sought to determine if CBD given in adolescence could prevent the development of the schizophrenia-relevant phenotype, as well as susceptibility to the psychoactive cannabinoid Δ⁹-tetrahydrocannabinol (THC) in Nrg1 TM HET mice. Adolescent male Nrg1 mutants and wild type-like (WT) animals were administered 30 mg/kg CBD i.p. daily for seven weeks, and were tested for locomotion, social behavior, sensorimotor gating and cognition, and sensitivity to acute THC-induced behaviors. GAD67, GluA1, and NMDAR1 protein levels were measured in the hippocampus, striatum, and prefrontal cortex. Chronic adolescent CBD increased locomotion in animals regardless of genotype, was anxiolytic, and increased social behavior when animals were tested for their acute THC response. CBD did not alleviate the schizophrenia-relevant hyperlocomotive phenotype of Nrg1 mutants, nor deficits in social behaviors. Nrg1 mutant mice treated with CBD and THC showed no habituation to a startle pulse, suggesting CBD increased vulnerability to the startle habituation-reducing effects of THC in mutant mice. CBD increased levels of GluA1, but reduced levels of GAD67 in the hippocampus of Nrg1 mutants. These results suggest adolescent CBD is not effective as a preventative of schizophrenia-relevant behavioral deficits in mutants and may actually contribute to pathological changes in the brain that increase sensitivity to THC in particular behavioral domains.

Effect of long-term cannabidiol on learning and anxiety in a female Alzheimer’s disease mouse model

Cannabidiol is a promising potential therapeutic for neurodegenerative diseases, including Alzheimer’s disease (AD). Our laboratory has shown that oral CBD treatment prevents cognitive impairment in a male genetic mouse model of AD, the amyloid precursor protein 1 x presenilin 1 hemizygous (APPxPS1) mouse. However, as sex differences are evident in clinical populations and in AD mouse models, we tested the preventive potential of CBD therapy in female APPxPS1 mice. In this study, 2.5-month-old female wildtype-like (WT) and APPxPS1 mice were fed 20 mg/kg CBD or a vehicle via gel pellets daily for 8 months and tested at 10.5 months in behavioural paradigms relevant to cognition (fear conditioning, FC; cheeseboard, CB; and novel object recognition test, NORT) and anxiety-like behaviours (elevated plus maze, EPM). In the CB, CBD reduced latencies to find a food reward in APPxPS1 mice, compared to vehicle-treated APPxPS1 controls, and this treatment effect was not evident in WT mice. In addition, CBD also increased speed early in the acquisition of the CB task in APPxPS1 mice. In the EPM, CBD increased locomotion in APPxPS1 mice but not in WT mice, with no effects of CBD on anxiety-like behaviour. CBD had limited effects on the expression of fear memory. These results indicate preventive CBD treatment can have a moderate spatial learning-enhancing effect in a female amyloid-β-based AD mouse model. This suggests CBD may have some preventive therapeutic potential in female familial AD patients.

Cannabidiol for the treatment of autism spectrum disorder: hope or hype?

RATIONALE

Autism spectrum disorder (ASD) is defined as a group of neurodevelopmental disorders whose symptoms include impaired communication and social interaction, restricted and repetitive patterns of behavior, and varying levels of intellectual disability. ASD is observed in early childhood and is one of the most severe chronic childhood disorders in prevalence, morbidity, and impact on society. It is usually accompanied by attention deficit hyperactivity disorder, anxiety, depression, sleep disorders, and epilepsy. The treatment of ASD has low efficacy, possibly because it has a heterogeneous nature, and its neurobiological basis is not clearly understood. Drugs such as risperidone and aripiprazole are the only two drugs available that are recognized by the Food and Drug Administration, primarily for treating the behavioral symptoms of this disorder. These drugs have limited efficacy and a high potential for inducing undesirable effects, compromising treatment adherence. Therefore, there is great interest in exploring the endocannabinoid system, which modulates the activity of other neurotransmitters, has actions in social behavior and seems to be altered in patients with ASD. Thus, cannabidiol (CBD) emerges as a possible strategy for treating ASD symptoms since it has relevant pharmacological actions on the endocannabinoid system and shows promising results in studies related to disorders in the central nervous system.

OBJECTIVES

Review the preclinical and clinical data supporting CBD's potential as a treatment for the symptoms and comorbidities associated with ASD, as well as discuss and provide information with the purpose of not trivializing the use of this drug.

Negative effects of brain regulatory T cells depletion on epilepsy

The infiltration of immune cells is observed in the epileptogenic zone; however, the relationship between epilepsy and regulatory T cells (Tregs) remains only partially understood. We aimed to investigate brain-infiltrating Tregs to reveal their underlying role in epilepsy. We analyzed the infiltration of Tregs in the epileptogenic zones from patients with epilepsy and a pilocarpine-induced temporal lobe epilepsy (TLE) model. Next, we evaluated the effects of brain Treg depletion on neuroinflammation, neuronal loss, oxidative stress, seizure activity and behavioral changes in the pilocarpine model. We also explored the impact of Treg expansion in the brain on seizure activity. There were a large number of Tregs in the epileptogenic zones of human and experimental epilepsy. The number of brain Tregs was negatively correlated with the frequency of seizures in patients with epilepsy. Our further findings demonstrated that brain Treg depletion promoted astrocytosis, microgliosis, inflammatory cytokine production, oxidative stress, and neuronal loss in the hippocampus after status epilepticus (SE). Moreover, brain Treg depletion increased seizure activity and contributed to behavioral impairments in experimental chronic TLE. Interestingly, intracerebroventricular injection of CCL20 amplified Tregs in brain tissue, thereby inhibiting seizure activity. Taken together, our study highlights the therapeutic potential of regulating Tregs in epileptic brain tissue.

Life-span characterization of epilepsy and comorbidities in Dravet syndrome mice carrying a targeted deletion of exon 1 of the Scn1a gene

OBJECTIVE

Dravet Syndrome (DS) is a catastrophic form of paediatric epilepsy associated with multiple comorbidities mainly caused by mutations in the SCN1A gene. DS progresses in three different phases termed febrile, worsening and stabilization stage. Mice that are haploinsufficient for Scn1a faithfully model each stage of DS, although various aspects have not been fully described, including the temporal appearance and sex differences of the epilepsy and comorbidities. The aim of the present study was to investigate the epilepsy landscape according to the progression of DS and the long-term co-morbidities in the Scn1a(+/-)^tm1Kea DS mouse line that are not fully understood yet.

METHODS

Male and female F1.Scn1a(+/+) and F1.Scn1a(+/-)^tm1Kea mice were assessed in the hyperthermia model or monitored by video electroencephalogram (vEEG) and wireless video-EEG according to the respective stage of DS. Long-term comorbidities were investigated through a battery of behaviour assessments in ~6 month-old mice.

RESULTS

At P18, F1.Scn1a(+/-)^tm1Kea mice showed the expected sensitivity to hyperthermia-induced seizures. Between P21 and P28, EEG recordings in F1.Scn1a(+/-)^tm1Kea mice combined with video monitoring revealed a high frequency of SRS and SUDEP. Power spectral analyses of background EEG activity also revealed that low EEG power in multiple frequency bands was associated with SUDEP risk in F1.Scn1a(+/-)^tm1Kea mice during the worsening stage of DS. Later, SRS and SUDEP rates stabilized and then declined in F1.Scn1a(+/-)^tm1kea mice. Incidence of SRS ending with death in F1.Scn1a(+/-)^tm1kea mice displayed variations with the time of day and sex, with female mice displaying higher numbers of severe seizures resulting in greater SUDEP risk. F1.Scn1a(+/-)^tm1kea mice ~6 month-old displayed fewer behavioural impairments than expected including hyperactivity, impaired exploratory behaviour and poor nest building performance.

SIGNIFICANCE

These results reveal new features of this model that will optimize use and selection of phenotype assays for future studies on the mechanisms, diagnosis, and treatment of DS.

Antiseizure Effects of Cannabidiol Leading to Increased Peroxisome Proliferator-Activated Receptor Gamma Levels in the Hippocampal CA3 Subfield of Epileptic Rats

We evaluated the effects of cannabidiol (CBD) on seizures and peroxisome proliferator-activated receptor gamma (PPARγ) levels in an animal model of temporal lobe epilepsy (TLE). Adult male Sprague-Dawley rats were continuously monitored by video-electrocorticography up to 10 weeks after an intraperitoneal kainic acid (15 mg/kg) injection. Sixty-seven days after the induction of status epilepticus and the appearance of spontaneous recurrent seizures in all rats, CBD was dissolved in medium-chain triglyceride (MCT) oil and administered subcutaneously at 120 mg/kg (n = 10) or 12 mg/kg (n = 10), twice a day for three days. Similarly, the vehicle was administered to ten epileptic rats. Brain levels of PPARγ immunoreactivity were compared to those of six healthy controls. CBD at 120 mg/kg abolished the seizures in 50% of rats (p = 0.033 vs. pre-treatment, Fisher’s exact test) and reduced total seizure duration (p < 0.05, Tukey Test) and occurrence (p < 0.05). PPARγ levels increased with CBD in the hippocampal CA1 subfield and subiculum (p < 0.05 vs. controls, Holm−Šidák test), but only the highest dose increased the immunoreactivity in the hippocampal CA3 subfield (p < 0.001), perirhinal cortex, and amygdala (p < 0.05). Overall, these results suggest that the antiseizure effects of CBD are associated with upregulation of PPARγ in the hippocampal CA3 region.

Channelopathy of Dravet Syndrome and Potential Neuroprotective Effects of Cannabidiol

Dravet syndrome (DS) is a channelopathy, neurodevelopmental, epileptic encephalopathy characterized by seizures, developmental delay, and cognitive impairment that includes susceptibility to thermally induced seizures, spontaneous seizures, ataxia, circadian rhythm and sleep disorders, autistic-like behaviors, and premature death. More than 80% of DS cases are linked to mutations in genes which encode voltage-gated sodium channel subunits, SCN1A and SCN1B, which encode the Nav1.1α subunit and Nav1.1β1 subunit, respectively. There are other gene mutations encoding potassium, calcium, and hyperpolarization-activated cyclic nucleotide-gated (HCN) channels related to DS. One-third of patients have pharmacoresistance epilepsy. DS is unresponsive to standard therapy. Cannabidiol (CBD), a non-psychoactive phytocannabinoid present in Cannabis, has been introduced for treating DS because of its anticonvulsant properties in animal models and humans, especially in pharmacoresistant patients. However, the etiological channelopathiological mechanism of DS and action mechanism of CBD on the channels are unclear. In this review, we summarize evidence of the direct and indirect action mechanism of sodium, potassium, calcium, and HCN channels in DS, especially sodium subunits. Some channels' loss-of-function or gain-of-function in inhibitory or excitatory neurons determine the balance of excitatory and inhibitory are associated with DS. A great variety of mechanisms of CBD anticonvulsant effects are focused on modulating these channels, especially sodium, calcium, and potassium channels, which will shed light on ionic channelopathy of DS and the precise molecular treatment of DS in the future.

Preclinical investigation of β-caryophyllene as a therapeutic agent in an experimental murine model of Dravet syndrome

Dravet Syndrome (DS) is caused by mutations in the Scn1a gene encoding the α1 subunit of the sodium channel Nav1.1, which results in febrile seizures that progress to severe tonic-clonic seizures and associated comorbidities. Treatment with cannabidiol has been approved for the management of seizures in DS patients, but it appears to be also active against associated comorbidities. In this new study, we have investigated β-caryophyllene (BCP), a cannabinoid with terpene structure that appears to also have a broad-spectrum profile, as a useful therapy against both seizuring activity and progression of associated comorbidities. This has been studied in heterozygous conditional knock-in mice carrying a missense mutation (A1783V) in Scn1a gene expressed exclusively in neurons of the Central Nervous System (Syn-Cre/Scn1a^WT/A1783V), using two experimental approaches. In the first approach, an acute treatment with BCP was effective against seizuring activity induced by pentylenetetrazole (PTZ) in wildtype (Scn1a^WT/WT) and also in Syn-Cre/Scn1a^WT/A1783V mice, with these last animals having a greater susceptibility to PTZ. Such benefits were paralleled by a BCP-induced reduction in PTZ-induced reactive astrogliosis (labelled with GFAP) and microgliosis (labelled with Iba-1) in the prefrontal cortex and the hippocampal dentate gyrus, which were visible in both wildtype (Scn1a^WT/WT) and Syn-Cre/Scn1a^WT/A1783V mice. In the second approach, both genotypes were treated repeatedly with BCP to investigate its effects on several DS comorbidities. Thus, BCP corrected important behavioural abnormalities of Syn-Cre/Scn1a^WT/A1783V mice (e.g. delayed appearance of hindlimb grasp reflex, induction of clasping response, motor hyperactivity, altered social interaction and memory impairment), attenuated weight loss, and slightly delayed premature mortality. Again, these benefits were paralleled by a BCP-induced reduction in reactive astrogliosis and microgliosis in the prefrontal cortex and the hippocampal dentate gyrus typical of Syn-Cre/Scn1a^WT/A1783V mice. In conclusion, BCP was active in Syn-Cre/Scn1a^WT/A1783V mice against seizuring activity (acute treatment) and against several comorbidities (repeated treatment), in both cases in association with its capability to reduce glial reactivity in areas related to these behavioural abnormalities. This situates BCP in a promising position for further preclinical evaluation towards a close translation to DS patients.

Cannabidiol (CBD) and cognition in epilepsy

Anecdotal reports of the benefits of cannabis and its components in the treatment of epilepsy have been reported for millennia. However, only recently randomized controlled trial data in support of cannabidiol (CBD) became available resulting in its FDA approval for the treatment of seizures and epilepsy. One of the most common and debilitating comorbidities of epilepsy is cognitive impairment. This impairment has a multifactorial etiology including network dysfunction due to seizures, negative cognitive side effects from anti-seizure medications (ASMs), and mood disturbances. Knowing the effects of a particular ASM (either positive or negative) is vital for providers to counsel patients on expected side effects, and may result in choosing a particular regimen over the other if the patient already suffers from significant cognitive deficits. Unlike most other ASMs and other well-studied cannabinoids such as Δ9-tetrahydrocannabinol, CBD has been shown to have additional mechanisms of action (MOA) that result in neuroprotective, anti-inflammatory, anti-oxidant, and neurogenesis effects. These additional MOAs suggest that the use of CBD could lead to other actions including positive effects on cognition that may be independent of seizure control. This targeted review discusses the currently available data on CBD's effects on cognition in epilepsy. First, we review the proposed mechanisms by which CBD could exert effects on cognition. Then, we present the pre-clinical/animal data investigating cognitive effects of CBD in seizure/epilepsy models. Finally, we discuss the available human data, including the studies in people with epilepsy that included cognitive evaluations pre- and on-CBD, and studies investigating if CBD has any effects on brain structure or function in areas pertinent to memory and cognitive functions.

Soticlestat, a novel cholesterol 24-hydroxylase inhibitor, reduces seizures and premature death in Dravet syndrome mice

OBJECTIVE

Dravet syndrome is a severe developmental and epileptic encephalopathy (DEE) most often caused by de novo pathogenic variants in SCN1A. Individuals with Dravet syndrome rarely achieve seizure control and have significantly elevated risk for sudden unexplained death in epilepsy (SUDEP). Heterozygous deletion of Scn1a in mice (Scn1a^+/- ) recapitulates several core phenotypes, including temperature-dependent and spontaneous seizures, SUDEP, and behavioral abnormalities. Furthermore, Scn1a^+/- mice exhibit a similar clinical response to standard anticonvulsants. Cholesterol 24-hydroxlase (CH24H) is a brain-specific enzyme responsible for cholesterol catabolism. Recent research has indicated the therapeutic potential of CH24H inhibition for diseases associated with neural excitation, including seizures.

METHODS

In this study, the novel compound soticlestat, a CH24H inhibitor, was administered to Scn1a^+/- mice to investigate its ability to improve Dravet-like phenotypes in this preclinical model.

RESULTS

Soticlestat treatment reduced seizure burden, protected against hyperthermia-induced seizures, and completely prevented SUDEP in Scn1a^+/- mice. Video-electroencephalography (EEG) analysis confirmed the ability of soticlestat to reduce occurrence of electroclinical seizures.

SIGNIFICANCE

This study demonstrates that soticlestat-mediated inhibition of CH24H provides therapeutic benefit for the treatment of Dravet syndrome in mice and has the potential for treatment of DEEs.

Cannabigerolic acid, a major biosynthetic precursor molecule in cannabis, exhibits divergent effects on seizures in mouse models of epilepsy

Background and Purpose

Cannabis has been used to treat epilepsy for millennia, with such use validated by regulatory approval of cannabidiol (CBD) for Dravet syndrome. Unregulated artisanal cannabis‐based products used to treat children with intractable epilepsies often contain relatively low doses of CBD but are enriched in other phytocannabinoids. This raises the possibility that other cannabis constituents might have anticonvulsant properties.

Experimental Approach

We used the Scn1a^+/− mouse model of Dravet syndrome to investigate the cannabis plant for phytocannabinoids with anticonvulsant effects against hyperthermia‐induced seizures. The most promising, cannabigerolic acid (CBGA), was further examined against spontaneous seizures and survival in Scn1a^+/− mice and in electroshock seizure models. Pharmacological effects of CBGA were surveyed across multiple drug targets.

Key Results

The initial screen identified three phytocannabinoids with novel anticonvulsant properties: CBGA, cannabidivarinic acid (CBDVA) and cannabigerovarinic acid (CBGVA). CBGA was most potent and potentiated the anticonvulsant effects of clobazam against hyperthermia‐induced and spontaneous seizures, and was anticonvulsant in the MES threshold test. However, CBGA was proconvulsant in the 6‐Hz threshold test and a high dose increased spontaneous seizure frequency in Scn1a^+/− mice. CBGA was found to interact with numerous epilepsy‐relevant targets including GPR55, TRPV1 channels and GABA_A receptors.

Conclusion and Implications

These results suggest that CBGA, CBDVA and CBGVA may contribute to the effects of cannabis‐based products in childhood epilepsy. Although these phytocannabinoids have anticonvulsant potential and could be lead compounds for drug development programmes, several liabilities would need to be overcome before CBD is superseded by another in this class.

Cannabidiol-based natural health products for companion animals: Recent advances in the management of anxiety, pain, and inflammation

Recent advances in cannabidiol (CBD) use in canines and felines for anxiety management, pain management, and anti-inflammatory effects were reviewed using a literature search conducted with the following keywords: CBD, anxiety, inflammation, pain, dogs, cats, and companion animals. For decades, research on CBD has been hindered due to the status of cannabis (C. sativa L.) as an illicit drug. Limited safety data show that CBD is well-tolerated in dogs, with insufficient information on the safety profile of CBD in cats. Upon oral supplementation of CBD, elevation in liver enzymes was observed for both dogs and cats, and pharmacokinetics of CBD are different in the two species. There is a significant gap in the literature on the therapeutic use of CBD in cats, with no feline data on anxiety, pain, and inflammation management. There is evidence that chronic osteoarthritic pain in dogs can be reduced by supplementation with CBD. Furthermore, experiments are required to better understand whether CBD has an influence on noise-induced fear and anxiolytic response. Preliminary evidence exists to support the analgesic properties of CBD in treating chronic canine osteoarthritis; however, there are inter- and intra-species differences in pharmacokinetics, tolerance, dosage, and safety of CBD. Therefore, to validate the anxiety management, pain management, and anti-inflammatory efficacy of CBD, it is essential to conduct systematic, randomized, and controlled trials. Further, the safety and efficacious dose of CBD in companion animals warrants investigation.

Combined Antiseizure Efficacy of Cannabidiol and Clonazepam in a Conditional Mouse Model of Dravet Syndrome

Dravet Syndrome (DS) is a severe childhood epilepsy caused by heterozygous loss-of-function mutations in the SCN1A gene encoding brain type-I voltage-gated sodium channel Na_v1.1. DS is a devastating disease that typically begins at six to nine months of age. Symptoms include recurrent intractable seizures and premature death with severe neuropsychiatric comorbidities, including hyperactivity, sleep disorder, anxiety-like behaviors, impaired social interactions, and cognitive deficits. There is an urgent unmet need for therapeutic approaches that control and cure DS, as available therapeutic interventions have poor efficacy, intolerance, or other side effects. Here we investigated the therapeutic potential of combining the benzodiazepine clonazepam (CLZ) with the nonpsychotropic phytocannabinoid cannabidiol (CBD) against thermally induced febrile seizures in a conditional mouse model of DS. Our results show that a low dose of CLZ alone or combined with CBD elevated the threshold temperature for the thermal induction of seizures. Combination of CLZ with CBD significantly reduced seizure duration compared to the vehicle or CLZ alone, but did not affect seizure severity, indicating potential additive actions of CLZ and CBD on the duration of seizures. Our findings provide preclinical evidence supporting combination therapy of CLZ and CBD for treatment of febrile seizures in DS.

Chronic cannabidiol (CBD) administration induces anticonvulsant and antiepileptogenic effects in a genetic model of epilepsy

Cannabidiol (CBD) is a marijuana compound implicated in epilepsy treatment in animal models and pharmacoresistant patients. However, little is known about chronic CBD administration's effects in chronic models of seizures, especially regarding its potential antiepileptogenic effects. In the present study, we combined a genetic model of epilepsy (the Wistar Audiogenic Rat strain - WARs), a chronic protocol of seizures (the audiogenic kindling - AuK), quantitative and sequential behavioral analysis (neuroethology), and microscopy imaging to analyze the effects of chronic CBD administration in a genetic model of epilepsy. The acute audiogenic seizure is characterized by tonic-clonic seizures and intense brainstem activity. However, during the AuK WARs can develop limbic seizures associated with the recruitment of forebrain and limbic structures. Here, chronic CBD administration, twice a day, attenuated brainstem, tonic-clonic seizures, prevented limbic recruitment, and suppressed limbic (kindled) seizures, suggesting CBD antiepileptogenic effects. Additionally, CBD prevented chronic neuronal hyperactivity, suppressing FosB immunostaining in the brainstem (inferior colliculus and periaqueductal gray matter) and forebrain (basolateral amygdala nucleus and piriform cortex), structures associated with tonic-clonic and limbic seizures, respectively. Chronic seizures increased cannabinoid receptors type 1 (CB1R) immunostaining in the hippocampus and the BLA, while CBD administration prevented changes in CB1R expression induced by the AuK. The neuroethological analysis provided details about CBD's protective effects against brainstem and limbic seizures associated with FosB expression. Our results strongly suggest chronic CBD anticonvulsant and antiepileptogenic effects associated with reduced chronic neuronal activity and modulation of CB1R expression. We also support the chronic use of CBD for epilepsies treatments.

Cannabinoids in Audiogenic Seizures: From Neuronal Networks to Future Perspectives for Epilepsy Treatment

Cannabinoids and Cannabis-derived compounds have been receiving especial attention in the epilepsy research scenario. Pharmacological modulation of endocannabinoid system's components, like cannabinoid type 1 receptors (CB1R) and their bindings, are associated with seizures in preclinical models. CB1R expression and functionality were altered in humans and preclinical models of seizures. Additionally, Cannabis-derived compounds, like cannabidiol (CBD), present anticonvulsant activity in humans and in a great variety of animal models. Audiogenic seizures (AS) are induced in genetically susceptible animals by high-intensity sound stimulation. Audiogenic strains, like the Genetically Epilepsy Prone Rats, Wistar Audiogenic Rats, and Krushinsky-Molodkina, are useful tools to study epilepsy. In audiogenic susceptible animals, acute acoustic stimulation induces brainstem-dependent wild running and tonic-clonic seizures. However, during the chronic protocol of AS, the audiogenic kindling (AuK), limbic and cortical structures are recruited, and the initially brainstem-dependent seizures give rise to limbic seizures. The present study reviewed the effects of pharmacological modulation of the endocannabinoid system in audiogenic seizure susceptibility and expression. The effects of Cannabis-derived compounds in audiogenic seizures were also reviewed, with especial attention to CBD. CB1R activation, as well Cannabis-derived compounds, induced anticonvulsant effects against audiogenic seizures, but the effects of cannabinoids modulation and Cannabis-derived compounds still need to be verified in chronic audiogenic seizures. The effects of cannabinoids and Cannabis-derived compounds should be further investigated not only in audiogenic seizures, but also in epilepsy related comorbidities present in audiogenic strains, like anxiety, and depression.

Is Cannabidiol During Neurodevelopment a Promising Therapy for Schizophrenia and Autism Spectrum Disorders?

Schizophrenia and autism spectrum disorders (ASD) are psychiatric neurodevelopmental disorders that cause high levels of functional disabilities. Also, the currently available therapies for these disorders are limited. Therefore, the search for treatments that could be beneficial for the altered course of the neurodevelopment associated with these disorders is paramount. Preclinical and clinical evidence points to cannabidiol (CBD) as a promising strategy. In this review, we discuss clinical and preclinical studies on schizophrenia and ASD investigating the behavioral, molecular, and functional effects of chronic treatment with CBD (and with cannabidivarin for ASD) during neurodevelopment. In summary, the results point to CBD's beneficial potential for the progression of these disorders supporting further investigations to strengthen its use.

Neuropathological Characterization of a Dravet Syndrome Knock-In Mouse Model Useful for Investigating Cannabinoid Treatments

Dravet syndrome (DS) is an epileptic syndrome caused by mutations in the Scn1a gene encoding the α1 subunit of the sodium channel Nav1.1, which is associated with febrile seizures that progress to severe tonic-clonic seizures and associated comorbidities. Treatment with cannabidiol has been approved to reduce seizures in DS, but it may also be active against these comorbidities. The aim of this study was to validate a new mouse model of DS having lower mortality than previous models, which may serve to further evaluate therapies for the long-term comorbidities. This new model consists of heterozygous conditional knock-in mice carrying a missense mutation (A1783V) in Scn1a gene expressed exclusively in neurons of the CNS (Syn-Cre/Scn1a^WT/A1783V). These mice have been used here to determine the extent and persistence of the behavioral deterioration in different postnatal days (PND), as well as to investigate the alterations that the disease produces in the endocannabinoid system and the contribution of inflammatory events and impaired neurogenesis in the pathology. Syn-Cre/Scn1a^WT/A1783V mice showed a strong reduction in hindlimb grasp reflex at PND10, whereas at PND25, they presented spontaneous convulsions and a greater susceptibility to pentylenetetrazole-induced seizures, marked hyperactivity, deficient spatial working memory, lower levels of anxiety, and altered social interaction behavior. These differences disappeared at PND40 and PND60, except the changes in social interaction and anxiety. The analysis of CNS structures associated with these behavioral alterations revealed an elevated glial reactivity in the prefrontal cortex and the dentate gyrus. This was associated in the dentate gyrus with a greater cell proliferation detected with Ki67 immunostaining, whereas double-labeling analyses identified that proliferating cells were GFAP-positive suggesting failed neurogenesis but astrocyte proliferation. The analysis of the endocannabinoid system of Syn-Cre/Scn1a^WT/A1783V mice confirmed reductions in CB₁ receptors and MAGL and FAAH enzymes, mainly in the cerebellum but also in other areas, whereas CB₂ receptors became upregulated in the hippocampus. In conclusion, Syn-Cre/Scn1a^WT/A1783V mice showed seizuring susceptibility and several comorbidities (hyperactivity, memory impairment, less anxiety, and altered social behavior), which exhibited a pattern of age expression similar to DS patients. Syn-Cre/Scn1a^WT/A1783V mice also exhibited greater glial reactivity and a reactive response in the neurogenic niche, and regional changes in the status of the endocannabinoid signaling, events that could contribute in behavioral impairment.

Development of cannabidiol as a treatment for severe childhood epilepsies

In recent years, there has been a growing appreciation by regulatory authorities that cannabis-based medicines can play a useful role in disease therapy. Although often conflagrated by proponents of recreational use, the legislative rescheduling of cannabis-derived compounds, such as cannabidiol (CBD), has been associated with the steady increase in the pursuit of use of medicinal cannabis. One key driver in this interest has been the scientific demonstration of efficacy and safety of CBD in randomised, placebo-controlled clinical trials in children and young adults with difficult-to-treat epilepsies, which has encouraged increasing numbers of human trials of CBD for other indications and in other populations. The introduction of CBD as the medicine Epidiolex in the United States (in 2018) and as Epidyolex in the European Union (in 2019) as the first cannabis-derived therapeutic for the treatment of seizures was underpinned by preclinical research performed at the University of Reading. This work was awarded the British Pharmacological Society Sir James Black Award for Contributions to Drug Discovery 2019 and is discussed in the following review article.

Cannabidiol improves survival and behavioural co-morbidities of Dravet syndrome in mice

Background and Purpose

Dravet syndrome is a severe, genetic form of paediatric epilepsy associated with premature mortality and co‐morbidities such as anxiety, depression, autism, motor dysfunction and memory deficits. Cannabidiol is an approved anticonvulsive drug in the United States and Europe for seizures associated with Dravet syndrome in patients 2 years of age and older. We investigated its potential to prevent premature mortality and improve associated co‐morbidities.

Experimental Approach

The efficacy of sub‐chronic cannabidiol administration in two mouse models of Dravet syndrome was investigated. The effect of cannabidiol on neonatal welfare and survival was studied using Scn1a^−/− mice. We then used a hybrid, heterozygote Scn1a^+/− mouse model to study the effect of cannabidiol on survival and behavioural co‐morbidities: motor deficits (rotarod and static‐beam test), gait abnormality (gait test), social anxiety (social interaction test), anxiety‐like (elevated plus maze) and depressive‐like behaviours (sucrose preference test) and cognitive impairment (radial arm maze test).

Key Results

In Scn1a^−/− mice, cannabidiol increased survival and delayed worsening of neonatal welfare. In Scn1a^+/− mice, chronic cannabidiol administration did not show any adverse effect on motor function and gait, reduced premature mortality, improved social behaviour and memory function, and reduced anxiety‐like and depressive‐like behaviours.

Conclusion and Implications

We are the first to demonstrate a potential disease‐modifying effect of cannabidiol in animal models of Dravet syndrome. Cannabidiol treatment reduced premature mortality and improved several behavioural co‐morbidities in Dravet syndrome mice. These crucial findings may be translated into human therapy to address behavioural co‐morbidities associated with Dravet syndrome.