Modulatory effects of cannabinoids on brain neurotransmission

Dynamic endocannabinoid-mediated neuromodulation of retinal circadian circuitry

Circadian rhythms are biological rhythms that originate from the "master circadian clock," called the suprachiasmatic nucleus (SCN). SCN orchestrates the circadian rhythms using light as a chief zeitgeber, enabling humans to synchronize their daily physio-behavioral activities with the Earth's light-dark cycle. However, chronic/ irregular photic disturbances from the retina via the retinohypothalamic tract (RHT) can disrupt the amplitude and the expression of clock genes, such as the period circadian clock 2, causing circadian rhythm disruption (CRd) and associated neuropathologies. The present review discusses neuromodulation across the RHT originating from retinal photic inputs and modulation offered by endocannabinoids as a function of mitigation of the CRd and associated neuro-dysfunction. Literature indicates that cannabinoid agonists alleviate the SCN's ability to get entrained to light by modulating the activity of its chief neurotransmitter, i.e., γ-aminobutyric acid, thus preventing light-induced disruption of activity rhythms in laboratory animals. In the retina, endocannabinoid signaling modulates the overall gain of the retinal ganglion cells by regulating the membrane currents (Ca2+, K+, and Cl- channels) and glutamatergic neurotransmission of photoreceptors and bipolar cells. Additionally, endocannabinoids signalling also regulate the high-voltage-activated Ca2+ channels to mitigate the retinal ganglion cells and intrinsically photosensitive retinal ganglion cells-mediated glutamate release in the SCN, thus regulating the RHT-mediated light stimulation of SCN neurons to prevent excitotoxicity. As per the literature, cannabinoid receptors 1 and 2 are becoming newer targets in drug discovery paradigms, and the involvement of endocannabinoids in light-induced CRd through the RHT may possibly mitigate severe neuropathologies.

Potential perioperative cardiovascular outcomes in cannabis/cannabinoid users. A call for caution

Background

Cannabis is one of the most widely used psychoactive substances. Its components act through several pathways, producing a myriad of side effects, of which cardiovascular events are the most life-threatening. However, only a limited number of studies address cannabis's perioperative impact on patients during noncardiac surgery.

Methods

Studies were identified by searching the PubMed, Medline, EMBASE, and Google Scholar databases using relevant keyword combinations pertinent to the topic.

Results

Current evidence shows that cannabis use may cause several cardiovascular events, including abnormalities in cardiac rhythm, myocardial infarction, heart failure, and cerebrovascular events. Additionally, cannabis interacts with anticoagulants and antiplatelet agents, decreasing their efficacy. Finally, the interplay of cannabis with inhalational and intravenous anesthetic agents may lead to adverse perioperative cardiovascular outcomes.

Conclusions

The use of cannabis can trigger cardiovascular events that may depend on factors such as the duration of consumption, the route of administration of the drug, and the dose consumed, which places these patients at risk of drug-drug interactions with anesthetic agents. However, large prospective randomized clinical trials are needed to further elucidate gaps in the body of knowledge regarding which patient population has a greater risk of perioperative complications after cannabis consumption.

The Use of Compounds Derived from Cannabis sativa in the Treatment of Epilepsy, Painful Conditions, and Neuropsychiatric and Neurodegenerative Disorders

Neurological disorders present a wide range of symptoms and challenges in diagnosis and treatment. Cannabis sativa, with its diverse chemical composition, offers potential therapeutic benefits due to its anticonvulsive, analgesic, anti-inflammatory, and neuroprotective properties. Beyond cannabinoids, cannabis contains terpenes and polyphenols, which synergistically enhance its pharmacological effects. Various administration routes, including vaporization, oral ingestion, sublingual, and rectal, provide flexibility in treatment delivery. This review shows the therapeutic efficacy of cannabis in managing neurological disorders such as epilepsy, neurodegenerative diseases, neurodevelopmental disorders, psychiatric disorders, and painful pathologies. Drawing from surveys, patient studies, and clinical trials, it highlights the potential of cannabis in alleviating symptoms, slowing disease progression, and improving overall quality of life for patients. Understanding the diverse therapeutic mechanisms of cannabis can open up possibilities for using this plant for individual patient needs.

Cannabinoids in the Treatment of Selected Mental Illnesses: Practical Approach and Overview of the Literature

Although an increasing number of patients suffering from mental illnesses self-medicate with cannabis, current knowledge about the efficacy and safety of cannabis-based medicine in psychiatry is still extremely limited. So far, no cannabis-based finished product has been approved for the treatment of a mental illness. There is increasing evidence that cannabinoids may improve symptoms in autism spectrum disorder (ASD), Tourette syndrome (TS), anxiety disorders, and post-traumatic stress disorder (PTSD). According to surveys, patients often use cannabinoids to improve mood, sleep, and symptoms of attention deficit/hyperactivity disorder (ADHD). There is evidence suggesting that tetrahydrocannabinol (THC) and THC-containing cannabis extracts, such as nabiximols, can be used as substitutes in patients with cannabis use disorder.Preliminary evidence also suggests an involvement of the endocannabinoid system (ECS) in the pathophysiology of TS, ADHD, and PTSD. Since the ECS is the most important neuromodulatory system in the brain, it possibly induces beneficial effects of cannabinoids by alterations in other neurotransmitter systems. Finally, the ECS is an important stress management system. Thus, cannabinoids may improve symptoms in patients with mental illnesses by reducing stress.Practically, cannabis-based treatment in patients with psychiatric disorders does not differ from other indications. The starting dose of THC-containing products should be low (1-2.5 mg THC/day), and the dose should be up-titrated slowly (by 1-2.5 mg every 3-5 days). The average daily dose is 10-20 mg THC. In contrast, cannabidiol (CBD) is mainly used in high doses>400 mg/day.

The Relationship between Muscarinic and Cannabinoid Receptors in Neuronal Excitability and Epilepsy: A Review

Background

Of the seventy million people who suffer from epilepsy, 40 percent of them become resistant to more than one antiepileptic medication and have a higher chance of death. While the classical definition of epilepsy was due to the imbalance between excitatory glutamatergic and inhibitory γ-aminobutyric acid (GABA)-ergic signalling, substantial evidence implicates muscarinic receptors in the regulation of neural excitability.

Summary

Cannabinoids have shown to reduce seizure activity and neuronal excitability in several epileptic models through the activation of muscarinic receptors with drugs which modulate their activity. Cannabinoids also have been effective in reducing antiepileptic activity in pharmaco-resistant individuals; however, the mechanism of its effects in temporal lobe epilepsy is not clear.

Key Messages

This review seeks to elucidate the relationship between muscarinic and cannabinoid receptors in epilepsy and neural excitability.

Association between non-medical cannabis legalization and emergency department visits for cannabis-induced psychosis

A major public health concern of cannabis legalization is that it may result in an increase in psychotic disorders. We examined changes in emergency department (ED) visits for cannabis-induced psychosis following the legalization and subsequent commercialization (removal of restrictions on retail stores and product types) of non-medical cannabis in Ontario, Canada (population of 14.3 million). We used health administrative data containing the cause of all ED visits to examine changes over three periods; 1) pre-legalization (January 2014-September 2018); 2) legalization with restrictions (October 2018 - February 2020); and 3) commercialization (March 2020 - September 2021). We considered subgroups stratified by age and sex and examined cocaine- and methamphetamine-induced psychosis ED visits as controls. During our study, there were 6300 ED visits for cannabis-induced psychosis. The restricted legalization period was not associated with changes in rates of ED visits for cannabis-induced psychosis relative to pre-legalization. The commercialization period was associated with an immediate increase in rates of ED visits for cannabis-induced psychosis (IRR 1.30, 95% CI 1.02-1.66) and no gradual monthly change; immediate increases were seen only for youth above (IRR 1.63, 1.27-2.08, ages 19-24) but not below (IRR 0.73 95%CI 0.42-1.28 ages, 15-18) the legal age of purchase, and similar for men and women. Commercialization was not associated with changes in rates of ED visits for cocaine- or methamphetamine-induced psychosis. This suggests that legalization with store and product restrictions does not increase ED visits for cannabis-induced psychosis. In contrast, cannabis commercialization may increase cannabis-induced psychosis presentations highlighting the importance of preventive measures in regions considering legalization.

Association of cannabis use with depression among cancer patients

The rate of cannabis use by cancer patients is climbing. However, as the risk of mental illness caused by cannabis use in cancer patients has not been effectively evaluated, this study will analyze the association between cannabis use and depression in cancer patients. This study collected data from respondents to the National Health and Nutrition Examination Survey from 2005 to 2018. A total of 22,181 respondents self-reported information about cannabis use in questionnaire, of which 893 were diagnosed with cancer. We found that the rate of cannabis use among cancer patients increased each year from 2005 to 2018. We analyzed the association between cannabis use and depression in cancer patients by multivariable logistic regression. Results found that the current cannabis use had a significant positive correlation with increased risk of depression in cancer patients (OR = 2.135, 95% CI = 1.21-3.777, p = 0.009). In our stratified analysis, current cannabis use was associated with an increased risk of depression in cancer patients who were female, had a history of cocaine use, and initiated cannabis use after age 17. (OR = 1.981, 95% CI = 1.024-3.85, P = 0.043; OR = 3.19, 95% CI = 1.61-6.41, P < 0.001; OR = 2.236, 95% CI = 1.018-4.967, P = 0.045). In conclusion, the use of cannabis by cancer patients has an associated risk of depression and the cancer patients who currently use cannabis are more likely to have depression.

Canadian Network for Mood and Anxiety Treatments (CANMAT) Task Force Report: A Systematic Review and Recommendations of Cannabis use in Bipolar Disorder and Major Depressive Disorder

BACKGROUND

Given the increasing acceptability and legalization of cannabis in some jurisdictions, clinicians need to improve their understanding of the effect of cannabis use on mood disorders.

OBJECTIVE

The purpose of this task force report is to examine the association between cannabis use and incidence, presentation, course and treatment of bipolar disorder and major depressive disorder, and the treatment of comorbid cannabis use disorder.

METHODS

We conducted a systematic literature review using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, searching PubMed, Embase, PsycINFO, CINAHL and Cochrane Central Register of Controlled Trials from inception to October 2020 focusing on cannabis use and bipolar disorder or major depressive disorder, and treatment of comorbid cannabis use disorder. The Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach was used to evaluate the quality of evidence and clinical considerations were integrated to generate Canadian Network for Mood and Anxiety Treatments recommendations.

RESULTS

Of 12,691 publications, 56 met the criteria: 23 on bipolar disorder, 21 on major depressive disorder, 11 on both diagnoses and 1 on treatment of comorbid cannabis use disorder and major depressive disorder. Of 2,479,640 participants, 12,502 were comparison participants, 73,891 had bipolar disorder and 408,223 major depressive disorder without cannabis use. Of those with cannabis use, 2,761 had bipolar disorder and 5,044 major depressive disorder. The lifetime prevalence of cannabis use was 52%-71% and 6%-50% in bipolar disorder and major depressive disorder, respectively. Cannabis use was associated with worsening course and symptoms of both mood disorders, with more consistent associations in bipolar disorder than major depressive disorder: increased severity of depressive, manic and psychotic symptoms in bipolar disorder and depressive symptoms in major depressive disorder. Cannabis use was associated with increased suicidality and decreased functioning in both bipolar disorder and major depressive disorder. Treatment of comorbid cannabis use disorder and major depressive disorder did not show significant results.

CONCLUSION

The data indicate that cannabis use is associated with worsened course and functioning of bipolar disorder and major depressive disorder. Future studies should include more accurate determinations of type, amount and frequency of cannabis use and select comparison groups which allow to control for underlying common factors.

Challenges of Treating ADHD with Comorbid Substance Use Disorder: Considerations for the Clinician

Adults with attention deficit/hyperactivity disorder (ADHD) often present psychiatric comorbidities and, in particular, substance use disorder (SUD). ADHD-SUD comorbidity is characterized by greater severity of both disorders, earlier age of onset, higher likelihood of polydrug-abuse and suicidal behaviors, more hospitalizations, and lower treatment adherence. At the present stage, research focused on the pharmacological management of ADHD with comorbid SUD in both adolescents and adults is still lacking. Furthermore, while the short-term effects of stimulants are well studied, less is known about the chronic effects of these drugs on dopamine signaling. Current available evidence is consistent in reporting that high doses of stimulant medications in ADHD-SUD subjects have a mild to moderate efficacy on ADHD symptoms. Some data suggest that pharmacological treatment with stimulants may be beneficial for both ADHD symptoms and comorbid cocaine or amphetamine use. However, in the long run, stimulant medications may have a potential risk for misuse. For the absence of potential misuse, atomoxetine is often recommended for ADHD with comorbid cocaine or amphetamine use disorder. However, its efficacy in reducing addictive behavior is not demonstrated. In subjects with other subtypes of SUD, both atomoxetine and stimulant drugs seem to have scarce impact on addictive behavior, despite the improvement in ADHD symptomatology. In this population, ADHD treatment should be combined with SUD-specific strategies.

Endocannabinoid system as a therapeutic target for psychostimulants relapse: A systematic review of preclinical studies

The mechanism behind the reinstament of psychostimulant, as a major obstacle in addiction treatment is not fully understood. Controversial data are available in the literature concerning the role of the endocannabinoid (eCB) system in regulating the relapse to psychostimulant addiction in preclinical studies. The current systematic review aims to evaluate eCB modulators' effect in the reinstatement of commonly abused psychostimulants, including cocaine, amphetamine, methamphetamine, and 3,4-methylenedioxymethamphetamine. By searching the PubMed, Web of Science, and Scopus databases, studies were selected. Then the studies^, quality was evaluated by the SYRCLE risk of bias tool. The results have still been limited to preclinical studies. Thirty-nine articles that employed self-administration and CPP as the most prevalent animal models of addiction were selected. This data indicates that cannabinoid receptor 1 antagonists and some cannabinoid receptor 2 agonists could suppress the reinstatement of cocaine and methamphetamine addiction in a dose-dependent manner. However, only AM251 was efficient to block the reinstatement of 3,4-methylenedioxymethamphetamine. In conclusion, cannabinoid receptor 1 antagonists and some cannabinoid receptor 2 agonists may have curative potential in the relapse of psychostimulant abuse. However, time, dose, and route of administration are crucial factors in their inhibitory impacts.

Deletion of Cryab increases the vulnerability of mice to the addiction-like effects of the cannabinoid JWH-018 via upregulation of striatal NF-κB expression

Synthetic cannabinoids have exhibited unpredictable abuse liabilities, especially self-administration (SA) responses in normal rodent models, despite seemingly inducing addiction-like effects in humans. Thus, an efficient pre-clinical model must be developed to determine cannabinoid abuse potential in animals and describe the mechanism that may mediate cannabinoid sensitivity. The Cryab knockout (KO) mice were recently discovered to be potentially sensitive to the addictive effects of psychoactive drugs. Herein, we examined the responses of Cryab KO mice to JWH-018 using SA, conditioned place preference, and electroencephalography. Additionally, the effects of repeated JWH-018 exposure on endocannabinoid- and dopamine-related genes in various addiction-associated brain regions were examined, along with protein expressions involving neuroinflammation and synaptic plasticity. Cryab KO mice exhibited greater cannabinoid-induced SA responses and place preference, along with divergent gamma wave alterations, compared to wild-type (WT) mice, implying their higher sensitivity to cannabinoids. Endocannabinoid- or dopamine-related mRNA expressions and accumbal dopamine concentrations after repeated JWH-018 exposure were not significantly different between the WT and Cryab KO mice. Further analyses revealed that repeated JWH-018 administration led to possibly greater neuroinflammation in Cryab KO mice, which may arise from upregulated NF-κB, accompanied by higher expressions of synaptic plasticity markers, which might have contributed to the development of cannabinoid addiction-related behavior in Cryab KO mice. These findings signify that increased neuroinflammation via NF-κB may mediate the enhanced addiction-like responses of Cryab KO mice to cannabinoids. Altogether, Cryab KO mice may be a potential model for cannabinoid abuse susceptibility.

Exogenous Cannabinoids Impair Effort-Related Decision-Making via Affecting Neural Synchronization between the Anterior Cingulate Cortex and Nucleus Accumbens

Humans and animals frequently make an endeavor-based choice based on assessing reinforcement value and response costs. The cortical-limbic-striatal pathway mediates endeavor-based choice behavior, including the nucleus accumbens (NAc) and the anterior cingulate cortex (ACC). Furthermore, cannabinoid agonists demonstratively impairs decision-making processes. In this study, neural synchronization and functional connectivity between the NAc and ACC while endeavor-related decision-making and reaching reward were evaluated. The effect of exogenous cannabinoids on this synchronization was then assessed. A T-maze decision-making task with a differential expense (low vs. high endeavor) and remuneration (low vs. high remuneration) was performed and local field potentials (LFP) from the ACC and NAc were registered simultaneously. Results showed functional connectivity during endeavor-related decision-making while the animals chose the high endeavor/high remuneration in both regions’ delta/beta (1–4 and 13–30 Hertz) frequency bands. Furthermore, functional connectivity existed between both areas in delta/theta (1–4 and 4–12) frequencies while reaching a remuneration. However, neural simultaneity was not observed while the animals received cannabinoid agonists, making a decision and reaching remuneration. The obtained results demonstrated that functional connectivity and neural simultaneity between the NAc and ACC in delta/beta and delta/theta frequencies have a role in endeavor-related decision-making and reaching remuneration, respectively. The effect of exogenous cannabinoids on decision-making impairment is relevant to changes in the ACC and NAC brain wave frequencies.

Synthetic Cannabinoids: A Pharmacological and Toxicological Overview

Synthetic cannabinoids (SCs) are a chemically diverse group of new psychoactive substances (NPSs) that target the endocannabinoid system, triggering a plethora of actions (e.g., elevated mood sensation, relaxation, appetite stimulation) that resemble, but are more intense than, those induced by cannabis. Although some of these effects have been explored for therapeutic applications, anticipated stronger psychoactive effects than cannabis and reduced risk perception have increased the recreational use of SCs, which have dominated the NPS market in the United States and Europe over the past decade. However, rising SC-related intoxications and deaths represent a major public health concern and embody a major challenge for policy makers. Here, we review the pharmacology and toxicology of SCs. A thorough characterization of SCs' pharmacodynamics and toxicodynamics is important to better understand the main mechanisms underlying acute and chronic effects of SCs, interpret the clinical/pathological findings related to SC use, and improve SC risk awareness.

The Endocannabinoid System and Physical Exercise

The endocannabinoid system (ECS) is involved in various processes, including brain plasticity, learning and memory, neuronal development, nociception, inflammation, appetite regulation, digestion, metabolism, energy balance, motility, and regulation of stress and emotions. Physical exercise (PE) is considered a valuable non-pharmacological therapy that is an immediately available and cost-effective method with a lot of health benefits, one of them being the activation of the endogenous cannabinoids. Endocannabinoids (eCBs) are generated as a response to high-intensity activities and can act as short-term circuit breakers, generating antinociceptive responses for a short and variable period of time. A runner's high is an ephemeral feeling some sport practitioners experience during endurance activities, such as running. The release of eCBs during sustained physical exercise appears to be involved in triggering this phenomenon. The last decades have been characterized by an increased interest in this emotional state induced by exercise, as it is believed to alleviate pain, induce mild sedation, increase euphoric levels, and have anxiolytic effects. This review provides information about the current state of knowledge about endocannabinoids and physical effort and also an overview of the studies published in the specialized literature about this subject.

Biological hypotheses, risk factors, and biomarkers of schizophrenia

Both the discovery of biomarkers of schizophrenia and the verification of biological hypotheses of schizophrenia are an essential part of the process of understanding the etiology of this mental disorder. Schizophrenia has long been considered a neurodevelopmental disease whose symptoms are caused by impaired synaptic signal transduction and brain neuroplasticity. Both the onset and chronic course of schizophrenia are associated with risk factors-induced disruption of brain function and the establishment of a new homeostatic setpoint characterized by biomarkers. Different risk factors and biomarkers can converge to the same symptoms of schizophrenia, suggesting that the primary cause of the disease can be highly individual. Schizophrenia-related biomarkers include measurable biochemical changes induced by stress (elevated allostatic load), mitochondrial dysfunction, neuroinflammation, oxidative and nitrosative stress, and circadian rhythm disturbances. Here is a summary of selected valid biological hypotheses of schizophrenia formulated based on risk factors and biomarkers, neurodevelopment, neuroplasticity, brain chemistry, and antipsychotic medication. The integrative neurodevelopmental-vulnerability-neurochemical model is based on current knowledge of the neurobiology of the onset and progression of the disease and the effects of antipsychotics and psychotomimetics and reflects the complex and multifactorial nature of schizophrenia.

Approaches for the discovery of drugs that target K Na 1.1 channels in KCNT1-associated epilepsy

INTRODUCTION

There are approximately 70 million people with epilepsy and about 30% of patients are not satisfactorily treated. A link between gene mutations and epilepsy is well documented. A number of pathological variants of KCNT1 gene (encoding the weakly voltage-dependent sodium-activated potassium channel - KNa 1.1) mutations has been found. For instance, epilepsy of infancy with migrating focal seizures, autosomal sleep-related hypermotor epilepsy or Ohtahara syndrome have been associated with KCNT1 gene mutations.

AREAS COVERED

Several methods for studies on KNa 1.1 channels have been reviewed - patch clamp analysis, Förster resonance energy transfer spectroscopy and whole-exome sequencing. The authors also review available drugs for the management of KCNT1 epilepsies.

EXPERT OPINION

The current methods enable deeper insights into electrophysiology of KNa 1.1 channels or its functioning in different activation states. It is also possible to identify a given KCNT1 mutation. Quinidine and cannabidiol show variable efficacy as add-on to baseline antiepileptic drugs so more effective treatments are required. A combined approach with the methods shown above, in silico methods and the animal model of KCNT1 epilepsies seems likely to create personalized treatment of patients with KCNT1 gene mutations.

Early Manifestation of Clozapine-Induced Cardiotoxicity: Detection, Pathophysiology, and Management

Schizoaffective disorder, bipolar type is a chronic mental health disorder that may manifest as mania. Clozapine is effective in treating acute mania and in achieving mood stabilization. However, on rare occasions, the use of clozapine has been associated with cardiotoxicity. Here, we present a case of a 31-year-old man who at baseline is known to have schizoaffective disorder, bipolar type, and cannabis dependence and was admitted to our hospital with a psychotic relapse. He was treated with clozapine, uptitrated to a maximum daily dose of 200mg twice daily by day 10. Thereafter he became febrile and experienced malaise, myalgias, and chest pain. He was noted on electrocardiogram to have sinus tachycardia without ischemic changes. In this context, he had a troponin leak, increased white blood cell count, serologies and cultures were negative and chest x-ray revealed no acute disease of the chest. Due to the suspicion of clozapine-induced cardiotoxicity, a transthoracic echocardiogram was done, which revealed mildly depressed left ventricular (LV) systolic function without pericardial effusion. Thereafter, clozapine was withdrawn and switched to lithium. Additionally, the cardioselective, metoprolol tartrate was initiated. Within 36-48 hours, he had resolution of symptoms and remained cardiovascularly stable. Clozapine uncommonly causes cardiotoxicity and early features may be non-specific. Awareness of this and recognizing early features aids in reducing the associated cardiovascular morbidity and mortality.

Chronic Pain and the Endocannabinoid System: Smart Lipids - A Novel Therapeutic Option?

The development of a high-end cannabinoid-based therapy is the result of intense translational research, aiming to convert recent discoveries in the laboratory into better treatments for patients. Novel compounds and new regimes for drug treatment are emerging. Given that previously unreported signaling mechanisms for cannabinoids have been uncovered, clinical studies detailing their high therapeutic potential are mandatory. The advent of novel genomic, optogenetic, and viral tracing and imaging techniques will help to further detail therapeutically relevant functional and structural features. An evolutionarily highly conserved group of neuromodulatory lipids, their receptors, and anabolic and catabolic enzymes are involved in a remarkable variety of physiological and pathological processes and has been termed the endocannabinoid system (ECS). A large body of data has emerged in recent years, pointing to a crucial role of this system in the regulation of the behavioral domains of acquired fear, anxiety, and stress-coping. Besides neurons, also glia cells and components of the immune system can differentially fine-tune patterns of neuronal activity. Dysregulation of ECS signaling can lead to a lowering of stress resilience and increased incidence of psychiatric disorders. Chronic pain may be understood as a disease process evoked by fear-conditioned nociceptive input and appears as the dark side of neuronal plasticity. By taking a toll on every part of your life, this abnormal persistent memory of an aversive state can be more damaging than its initial experience. All strategies for the treatment of chronic pain conditions must consider stress-related comorbid conditions since cognitive factors such as beliefs, expectations, and prior experience (memory of pain) are key modulators of the perception of pain. The anxiolytic and anti-stress effects of medical cannabinoids can substantially modulate the efficacy and tolerability of therapeutic interventions and will help to pave the way to a successful multimodal therapy. Why some individuals are more susceptible to the effects of stress remains to be uncovered. The development of personalized prevention or treatment strategies for anxiety and depression related to chronic pain must also consider gender differences. An emotional basis of chronic pain opens a new horizon of opportunities for developing treatment strategies beyond the repeated sole use of acutely acting analgesics. A phase I trial to determine the pharmacokinetics, psychotropic effects, and safety profile of a novel nanoparticle-based cannabinoid spray for oromucosal delivery highlights a remarkable innovation in galenic technology and urges clinical studies further detailing the huge therapeutic potential of medical cannabis (Lorenzl et al.; this issue).

Biomarkers of the Endocannabinoid System in Substance Use Disorders

Despite substance use disorders (SUD) being one of the leading causes of disability and mortality globally, available therapeutic approaches remain ineffective. The difficulty in accurately characterizing the neurobiological mechanisms involved with a purely qualitative diagnosis is an obstacle to improving the classification and treatment of SUD. In this regard, identifying central and peripheral biomarkers is essential to diagnosing the severity of drug dependence, monitoring therapeutic efficacy, predicting treatment response, and enhancing the development of safer and more effective pharmacological tools. In recent years, the crucial role that the endocannabinoid system (ECS) plays in regulating the reinforcing and motivational properties of drugs of abuse has been described. This has led to studies characterizing ECS alterations after exposure to various substances to identify biomarkers with potential diagnostic, prognostic, or therapeutic utility. This review aims to compile the primary evidence available from rodent and clinical studies on how the ECS components are modified in the context of different substance-related disorders, gathering data from genetic, molecular, functional, and neuroimaging experimental approaches. Finally, this report concludes that additional translational research is needed to further characterize the modifications of the ECS in the context of SUD, and their potential usefulness in the necessary search for biomarkers.

Sex specific effects of the fatty acid amide hydrolase inhibitor URB597 on memory and brain β2-adrenergic and D1-dopamine receptors

An increasing body of evidence shows significant sex differences in the mammalian brain in multiple behaviours and psychiatric and neurological diseases and as well as that the endocannabinoid system may differ between males and females. In this study we investigated sex differences in working, short-term and long-term memory and the expression of β₂-adrenergic and D1- and D2-receptors in the mPFC and hippocampus, brain regions that are involved in stress response and memory modulation in rats exposed to the chronic unpredictable stress (CUS) and the potential beneficial effects of the chronic fatty acid amide hydrolase inhibitor URB597 treatment. Chronically stressed male rats had an improvement of working memory, while stressed females showed very low object-recognition abilities. On the other hand, animals of both sexes exhibited long-term memory impairment. Our results showed that CUS decreased the expression of β₂-adrenoceptors in the mPFC and D1 receptors in the mPFC and hippocampus of male rats and decreased β₂-adrenoceptors and D1- receptors in the hippocampus of female. URB597 treatment had a positive effect on the short-term memory of stressed animals of both sexes whereas failed to restore long-term memory and did not affect the protein levels β2-adrenoceptors and D1 receptors in the hippocampus of CUS female rats. The present results support that endocannabinoids induced long-term memory and neurochemical alternations which are sex dependent, suggesting sex specific treatment strategies of mental disorders.

Prevalence of marijuana use in pregnant women with concurrent opioid use disorder or alcohol use in pregnancy

BACKGROUND

A quarter of pregnant women use alcohol, 6.5/1000 deliveries are affected by opioid use disorder (OUD), and the prevalence of cannabis use in pregnant women is increasing. However, marijuana co-exposure in polysubstance-using women is not well described.

METHODS

The well-characterized ENRICH-1 cohort (n = 251), which focused on the effects of two primary exposures of interest-opioids and alcohol, was used to (1) estimate the prevalence/frequency of marijuana use in those with OUD and/or alcohol use, and (2) examined correlates of marijuana use. Participants were classified into an OUD group (n = 125), Alcohol group (n = 69), and concurrent OUD and Alcohol (OUD + Alcohol) group (n = 57). Self-report and biomarkers ascertained substance use. Multivariable logistic regression identified correlates of marijuana use.

RESULTS

The prevalence of any marijuana use in pregnancy was 43.2%, 52.6%, and 46.4% in the OUD, OUD + Alcohol, and Alcohol groups, respectively. Correspondingly, weekly or daily use was reported by 19.4%, 21.0%, and 24.6% of participants. In the OUD and OUD + Alcohol groups, the proportion of women using marijuana was significantly higher in those taking buprenorphine (45.8% and 58.3%, respectively) compared to women using methadone (37.5% and 42.9%, respectively). Mean maternal age was lower in women who used marijuana in all three groups compared to non-marijuana users. Independent correlates of marijuana use (controlling for group, race/ethnicity, education, and smoking) were maternal age (adjusted Odds Ratio (aOR) per 5-year increment 0.61; (95% CI 0.47, 0.79)), and polysubstance use (aOR 2.02; 95% CI 1.11, 3.67). There was a significant interaction between partnership status and group: among women who were not in a partnership, those in the OUD and OUD + Alcohol groups had lower odds of marijuana use relative to the Alcohol group. For women in the Alcohol group, partnered women had lower odds of marijuana use than un-partnered women (aOR 0.12; 95% CI: 0.02, 0.68).

CONCLUSIONS

Results indicate a relatively high prevalence and frequency of marijuana use in pregnant women being treated for OUD and/or women consuming alcohol while pregnant. These results highlight the need for ongoing risk reduction strategies addressing marijuana use for pregnant women receiving OUD treatment and those with alcohol exposure.

Results from a randomized, double-blind, placebo-controlled, crossover, multimodal-MRI pilot study of gabapentin for co-occurring bipolar and cannabis use disorders

Disrupted brain gamma-aminobutyric acid (GABA)/glutamate homeostasis is a promising target for pharmacological intervention in co-occurring bipolar disorder (BD) and cannabis use disorder (CUD). Gabapentin is a safe and well-tolerated medication, FDA-approved to treat other neurological diseases, that restores GABA/glutamate homeostasis, with treatment studies supporting efficacy in treating CUD, as well as anxiety and sleep disorders that are common to both BD and CUD. The present manuscript represents the primary report of a randomized, double-blind, placebo-controlled, crossover (1-week/condition), multimodal-MRI (proton-MR spectroscopy, functional MRI) pilot study of gabapentin (1200 mg/day) in BD + CUD (n = 22). Primary analyses revealed that (1) gabapentin was well tolerated and adherence and retention were high, (2) gabapentin increased dorsal anterior cingulate cortex (dACC) and right basal ganglia (rBG) glutamate levels and (3) gabapentin increased activation to visual cannabis cues in the posterior midcingulate cortex (pMCC, a region involved in response inhibition to rewarding stimuli). Exploratory evaluation of clinical outcomes further found that in participants taking gabapentin versus placebo, (1) elevations of dACC GABA levels were associated with lower manic/mixed and depressive symptoms and (2) elevations of rBG glutamate levels and pMCC activation to cannabis cues were associated with lower cannabis use. Though promising, the findings from this study should be interpreted with caution due to observed randomization order effects on dACC glutamate levels and identification of statistical moderators that differed by randomization order (i.e. cigarette-smoking status on rBG glutamate levels and pMCC cue activation). Nonetheless, they provide the necessary foundation for a more robustly designed (urn-randomized, parallel-group) future study of adjuvant gabapentin for BD + CUD.

Possible actions of cannabidiol in obsessive-compulsive disorder by targeting the WNT/β-catenin pathway

Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder characterized by recurrent and distinctive obsessions and/or compulsions. The etiologies remain unclear. Recent findings have shown that oxidative stress, inflammation, and glutamatergic pathways play key roles in the causes of OCD. However, first-line therapies include cognitive-behavioral therapy but only 40% of the patients respond to this first-line therapy. Research for new treatment is mandatory. This review focuses on the potential effects of cannabidiol (CBD), as a potential therapeutic strategy, on OCD and some of the presumed mechanisms by which CBD provides its benefit properties. CBD medication downregulates GSK-3β, the main inhibitor of the WNT/β-catenin pathway. The activation of the WNT/β-catenin could be associated with the control of oxidative stress, inflammation, and glutamatergic pathway and circadian rhythms dysregulation in OCD. Future prospective clinical trials could focus on CBD and its different and multiple interactions in OCD.

The effect of URB597, exercise or their combination on the performance of 6-OHDA mouse model of Parkinson disease in the elevated plus maze, tail suspension test and step-down task

Parkinson disease (PD) is a progressive neurodegenerative disorder that is often accompanied by motor and psychiatric symptoms. Various approaches have been proposed for the treatment of PD. Here, we investigated the effect of a low dose of fatty acid amide hydrolase inhibitor URB597 (as an enhancer of endocannabinoid anandamide levels), exercise or their combination on some behavior alterations in PD mice lesioned by 6-hydroxydopamine (6-OHDA). The impact of swimming exercise (5×/week for 4 weeks) and URB597 (0.1 mg/kg, 2×/week for 4 weeks) on the anxiety-related behavior (elevated plus maze; EPM), depression-related behavior (tail suspension test; TST), and passive avoidance memory (step-down task) was examined in the sham and male NMRI mouse of PD model. The results show that URB597 prevented memory deficits and elicited antidepressant- and anxiolytic-like effects but did not affect hypolocomotion in the PD mice. However, URB597 did not have a significant effect on the performance of the sham mice in the performed tests. Moreover, swimming training abolished depressive- and anxiogenic-like behaviors and increased locomotion without affecting memory deficits in the PD mice. Meanwhile, swimming decreased immobility time and increased locomotion in the sham mice. Furthermore, URB597 in association with swimming training prevented all deficits induced in the PD mice, while this combination impaired memory and produced the positive effects on depression- and anxiety-related behaviors and locomotion of the sham mice. It is concluded that although URB597 or exercise alone had positive effects on most behavioral tests, their combination improved all parameters in the PD mice.

Plasmatic endocannabinoids are decreased in subjects with ultra-high risk of psychosis

The onset of frank psychosis is usually preceded by a prodromal phase characterized by attenuated psychotic symptoms. Currently, research on schizophrenia prodromal phase (ultra-high risk for psychosis [UHR]) has focused on the risk of developing psychosis, on the transition to full blown psychosis and on its prediction. Neurobiological differences between UHR individuals who fully recover (remitters) versus those who show persistent/progressive prodromal symptoms (nonremitters) have been little explored. The endocannabinoid system constitutes a neuromodulatory system that plays a major role in brain development, synaptic plasticity, emotional behaviours and cognition. It comprises two cannabinoid receptors (CB1/CB2), two endocannabinoid ligands, arachidonylethanolamide (AEA) and 2-arachidonoylglycerol (2AG) along with their inactivation enzymes. Despite much evidence that the endocannabinoid system is imbalanced during psychosis, very little is known about it in UHR. Therefore, we aimed to quantify the plasma endocannabinoid levels in UHR and healthy controls (HC) and verify if these metabolites could differentiate between remitters and nonremitters. Circulating concentrations of AEA (p = .003) and 2AG (p < .001) were lower in UHR when compared with HC, with no difference between remitters and nonremitters. Regarding clinical evolution, it was observed that out of 91 UHRs initially considered, 16 had psychiatric complaints (3 years of follow-up). Considering those subjects, there were weak correlations between clinical parameters and plasma concentrations of endocannabinoids. Our results suggest that the endocannabinoids are imbalanced before frank psychosis and that changes can be seen in plasma of UHR individuals. These molecules proved to be potential biomarkers to identify individuals in the prodromal phase of psychosis.

Progress on the application of positron emission tomography imaging of cannabinoid type 1 receptor in neuropsychiatric diseases

Cannabinoid type 1 receptor (CB1R), as the major member of the endocannabinoid system, is among the most abundant receptors expressed in the central nervous system. CB1R is mainly located on the axon terminals of presynaptic neurons and participate in the modulation of neuronal excitability and synaptic plasticity, playing an important role in the pathogenesis of various neuropsychiatric diseases. In recent years, the consistent development of CB1R radioligands and the maturity of molecular imaging techniques, particularly positron emission tomography (PET) may help to visualize the expression and distribution of CB1R in central nervous system . At present, CB1R PET imaging can effectively evaluate the changes of CB1R levels in neuropsychiatric diseases such as Huntington's disease and schizophrenia, and its correlation with the disease severity, therefore providing new insights for the diagnosis and treatment of neuropsychiatric diseases. This article reviews the application of CB1R PET imaging in Alzheimer's disease, Parkinson's disease, Huntington's disease, schizophrenia, post-traumatic stress disorder, cannabis use disorder and depression.

Acute cannabidiol treatment attenuates ethanol-induced place preference and reduces aggressivity in group-housed male rats

Alcohol abuse is a widespread cause of aggressive and impulsive behaviors that impact the users as well as their entourage. However, only a few medications are effective. Recently, cannabidiol has been reported to improve mood disorders and recovery from substance abuse, yet the psychopharmacologic effects of cannabidiol in ethanol-induced drug reward and aggressivity remain unexplored. In the present study, we investigated the effects of cannabidiol on ethanol-induced place preference and aggressivity in individually and group-housed male rats using the conditioned place preference test, and intruder evoc aggression test, respectively. The obtained results showed that ethanol significantly increased locomotor activity, induced conditioned place preference in all animals, and, specifically, increased aggressivity in individually housed rats. These behavioural impairments induced by ethanol were associated with decreased glucocorticoid and mineralocorticoid receptors transcription in the prefrontal cortex. Notwithstanding, cannabidiol at a dose of 10 mg/kg significantly inhibited Et-OH-induced place preference in group-housed, but not in individually housed rats, and markedly inhibited the aggressive behaviour. These findings suggest that ethanol-induced behavioural impairments are dependent on the housing condition that may affect corticosterone receptors expression and subsequently the animal responsivity to cannabidiol treatment.

Cannabis Dopaminergic Effects Induce Hallucinations in a Patient with Parkinson's Disease

Cannabis products that contain the tetrahydrocannabinol (THC) cannabinoid are emerging as promising therapeutic agents for the treatment of medical conditions such as chronic pain. THC elicits psychoactive effects through modulation of dopaminergic neurons, thereby altering levels of dopamine in the brain. This case report highlights the complexity associated with medicinal cannabis and the health risks associated with its use. A 57-year-old male with Parkinson’s disease was experiencing worsening tremors and vivid hallucinations despite therapy optimization attempts. It was discovered that the patient took cannabis for chronic back pain, and a pharmacogenomics (PGx) test indicated the presence of variants for the COMT and HTR2A genes. These variants could increase dopamine levels and predispose patients to visual hallucinations. Once the cannabis was discontinued, the patient’s hallucinations began to slowly dissipate. Cannabis use continues to expand as it gains more acceptance legally and medicinally, but cannabis can affect the response to drugs. This patient case suggests that cannabis use in combination with dopamine-promoting drugs, especially in a patient with genetic variants, can increase the risk for vivid hallucinations. These conditions support the importance of considering herb–drug interactions and PGx data when performing a medication safety review.

Neuromodulation of Hippocampal-Prefrontal Cortical Synaptic Plasticity and Functional Connectivity: Implications for Neuropsychiatric Disorders

The hippocampus-prefrontal cortex (HPC-PFC) pathway plays a fundamental role in executive and emotional functions. Neurophysiological studies have begun to unveil the dynamics of HPC-PFC interaction in both immediate demands and long-term adaptations. Disruptions in HPC-PFC functional connectivity can contribute to neuropsychiatric symptoms observed in mental illnesses and neurological conditions, such as schizophrenia, depression, anxiety disorders, and Alzheimer's disease. Given the role in functional and dysfunctional physiology, it is crucial to understand the mechanisms that modulate the dynamics of HPC-PFC communication. Two of the main mechanisms that regulate HPC-PFC interactions are synaptic plasticity and modulatory neurotransmission. Synaptic plasticity can be investigated inducing long-term potentiation or long-term depression, while spontaneous functional connectivity can be inferred by statistical dependencies between the local field potentials of both regions. In turn, several neurotransmitters, such as acetylcholine, dopamine, serotonin, noradrenaline, and endocannabinoids, can regulate the fine-tuning of HPC-PFC connectivity. Despite experimental evidence, the effects of neuromodulation on HPC-PFC neuronal dynamics from cellular to behavioral levels are not fully understood. The current literature lacks a review that focuses on the main neurotransmitter interactions with HPC-PFC activity. Here we reviewed studies showing the effects of the main neurotransmitter systems in long- and short-term HPC-PFC synaptic plasticity. We also looked for the neuromodulatory effects on HPC-PFC oscillatory coordination. Finally, we review the implications of HPC-PFC disruption in synaptic plasticity and functional connectivity on cognition and neuropsychiatric disorders. The comprehensive overview of these impairments could help better understand the role of neuromodulation in HPC-PFC communication and generate insights into the etiology and physiopathology of clinical conditions.

The endocannabinoidome in neuropsychiatry: Opportunities and potential risks

The endocannabinoid system (ECS) comprises two cognate endocannabinoid receptors referred to as CB1R and CB2R_. ECS dysregulation is apparent in neurodegenerative/neuro-psychiatric disorders including but not limited to schizophrenia, major depressive disorder and potentially bipolar disorder. The aim of this paper is to review mechanisms whereby both receptors may interact with neuro-immune and neuro-oxidative pathways, which play a pathophysiological role in these disorders. CB1R is located in the presynaptic terminals of GABAergic, glutamatergic, cholinergic, noradrenergic and serotonergic neurons where it regulates the retrograde suppression of neurotransmission. CB1R plays a key role in long-term depression, and, to a lesser extent, long-term potentiation, thereby modulating synaptic transmission and mediating learning and memory. Optimal CB1R activity plays an essential neuroprotective role by providing a defense against the development of glutamate-mediated excitotoxicity, which is achieved, at least in part, by impeding AMPA-mediated increase in intracellular calcium overload and oxidative stress. Moreover, CB1R activity enables optimal neuron-glial communication and the function of the neurovascular unit. CB2R receptors are detected in peripheral immune cells and also in central nervous system regions including the striatum, basal ganglia, frontal cortex, hippocampus, amygdala as well as the ventral tegmental area. CB2R upregulation inhibits the presynaptic release of glutamate in several brain regions. CB2R activation also decreases neuroinflammation partly by mediating the transition from a predominantly neurotoxic "M1" microglial phenotype to a more neuroprotective "M2" phenotype. CB1R and CB2R are thus novel drug targets for the treatment of neuro-immune and neuro-oxidative disorders including schizophrenia and affective disorders.

Effects of GABAA receptors in nucleus cuneiformis on the cannabinoid antinociception using the formalin test

RATIONALE

Nucleus cuneiformis (NC), a reticular nucleus of the midbrain, is a part of the descending pain modulatory system and therefore has an important role in pain perception.

OBJECTIVES

Considering the abundance of GABA_A and cannabinoid receptors in the NC and also the bidirectional roles for GABA in controlling nociception, the present study examined the effects of bilateral intra-NC microinjection of different doses of the GABA_A receptor agonist, muscimol, and the GABA_A receptor antagonist, bicuculline, on pain modulation using formalin test. We also assessed interaction between canabinergic and GABAergic systems in the NC during this test.

METHODS

Rats were exposed to intra-NC microinjection of bicuculline (50,100, and 200 ng/side) or muscimol (60, 120, and 240 ng/side) and then subjected to the formalin test. In another set of experiments, the effects of muscimol (60 ng/side) or bicuculline (50 ng/side) administration 5 min before a cannabinoid receptor agonist WIN 55,212-2 (5, 10, and 20 μg/side) microinjection into NC on the formalin test were evaluated.

RESULTS

Microinjection of bicuculline and muscimol into the NC decreased and increased pain responses, respectively, in a dose-dependent manner during both phases of the test. Microinjection of WIN 55,212-2 into the NC significantly reduced pain responses in a dose-dependent manner. Microinjection of bicuculline or muscimol in combination with WIN 55,212-2 into the NC respectively potentiated and attenuated WIN 55,212-2-induced antinociception in the formalin test.

CONCLUSIONS

This study shows that GABA in the NC is involved in pain modulation and suggests the existence of a GABA_A-mediated inhibitory system in the NC on pain control. Furthermore, it seems that the antinociceptive effect of WIN 55,212-2 in the formalin test is mediated partly by the activity of local GABA_A receptors in the NC.

Down and High: Reflections Regarding Depression and Cannabis

In light of the recent changes in the legal status of cannabis in Canada, the understanding of the potential impact of the use of cannabis by individuals suffering from depression is increasingly considered as being important. It is fundamental that we look into the existing literature to examine the influence of cannabis on psychiatric conditions, including mood disorders. In this article, we will explore the relationship that exists between depression and cannabis. We will examine the impact of cannabis on the onset and course of depression, and its treatment. We have undertaken a wide-ranging review of the literature in order to address these questions. The evidence from longitudinal studies suggest that there is a bidirectional relationship between cannabis use and depression, such that cannabis use increases the risk for depression and vice-versa. This risk is possibly higher in heavy users having initiated their consumption in early adolescence. Clinical evidence also suggests that cannabis use is associated with a worse prognosis in individuals with major depressive disorder. The link with suicide remains controversial. Moreover, there is insufficient data to determine the impact of cannabis use on cognition in individuals with major depression disorder. Preliminary evidence suggesting that the endogenous cannabinoid system is involved in the pathophysiology of depression. This will need to be confirmed in future positron emission tomography studies. Randomized controlled trials are needed to investigate the potential efficacy of motivational interviewing and/or cognitive behavioral therapy for the treatment of cannabis use disorder in individuals with major depressive major disorder. Finally, although there is preclinical evidence suggesting that cannabidiol has antidepressant properties, randomized controlled trials will need to properly investigate this possibility in humans.

Cannabis and Cannabinoids in Reproduction and Fertility: Where We Stand

Although cannabis use is increasing in general population, their prevalence among young adults is remarkably high. In recent years, their medical use gained a renewed interest. However, it can underline the reputation of cannabis being a harmless drug. Between cannabinoids, uniquely found on the cannabis plant, Δ⁹-tetrahydrocannabinol (THC) is the well-studied compound. It is responsible for the psychoactive effects via central cannabinoid receptors. Nevertheless, cannabinoids interact with other chemical signalling systems such as the hypothalamic-pituitary-gonadal axis. THC indirectly decreases gonadotropin-releasing hormone (GnRH) secretion by the hypothalamus. The consequences are diverse, and several key hormones are affected. THC disturbs important reproductive events like folliculogenesis, ovulation and sperm maturation and function. Although generally accepted that cannabinoid consumption impacts male and female fertility, prevailing evidence remains largely on pre-clinical studies. Here, we introduce cannabinoids and the endocannabinoid system, and we review the most prominent clinical evidence about cannabis consumption in reproductive potential and teratogenicity.

Does Cannabis, Cocaine and Alcohol Use Impact Differently on Adult Attention Deficit/Hyperactivity Disorder Clinical Picture?

While the association between adult Attention Deficit/Hyperactivity Disorder (A-ADHD) and Substance Use Disorders (SUDs) has been widely explored, less attention has been dedicated to the various substance use variants. In a previous paper, we identified two variants: type 1 (use of stimulants/alcohol) and type 2 (use of cannabinoids). In this study, we compared demographic, clinical and symptomatologic features between Dual Disorder A-ADHD (DD/A-ADHD) patients according to our substance use typology, and A-ADHD without DD (NDD/A-ADHD) ones. NDD patients were more frequently diagnosed as belonging to inattentive ADHD subtype compared with type 1 DD/A-ADHD patients, but not with respect to type 2 DD/ADHD. NDD/A-ADHD patients showed less severe symptoms of hyperactivity/impulsivity than DD/A-ADHD type 1, but not type 2. Type 1 and type 2 patients shared the feature of displaying higher impulsiveness than NDD/A-ADHD ones. General psychopathology scores were more severe in type 2 DD/ADHD patients, whereas type 1 patients showed greater similarity to NDD/A-ADHD. Legal problems were more strongly represented in type 1 than in type 2 patients or NDD/A-ADHD ones. Our results suggest that type 1 and type 2 substance use differ in their effects on A-ADHD patients-an outcome that brings with it different likely implications in dealing with the diagnostic and therapeutic processes.

Endocannabinoid and dopaminergic system: the pas de deux underlying human motivation and behaviors

Endocannabinoid system (ECS) has been identified ever since cannabinoid, an active substance of Cannabis, was known to interact with endogenous cannabinoid (endocannabinoid/eCB) receptors. It later turned out that eCB was more intricate than previously thought. It has a pervasive role and exerts a multitude of cellular signaling mechanisms, regulating various physiological neurotransmission pathways in the human brain, including the dopaminergic (DA) system. eCB roles toward DA system were robust, clearly delineated, and reproducible with respect to physiological as well as pathological neurochemical and neurobehavioral manifestations of DA system, particularly those involving the nigrostriatal and mesocorticolimbic pathways. The eCB–DA system regulates the basics in the Maslow’s pyramid of hierarchy of needs required for individual survival such as food and sexual activity for reproductive purpose to those of higher needs in the pyramid, including self-actualization behaviors leading to achievement and reward (e.g., academic- and/or work-related performance and achievements). It is, thus, interesting to specifically discuss the eCB–DA system, not only on the molecular level, but also its tremendous potential to be developed as a future therapeutic strategy for various neuropsychiatric problems, including obesity, drug addiction and withdrawal, pathological hypersexuality, or low motivation behaviors.

Cannabinoids and orthopedic surgery: a systematic review of therapeutic studies

Background

Recent work has shed light on the potential benefits of cannabinoids for multimodal pain control following orthopedic procedures. The objective of this review was to summarize the available evidence of analgesic and opioid-sparing effects cannabinoids have in orthopedic surgery and identify adverse events associated with their use.

Methods

A systematic review of the literature using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines including PubMed, EMBASE, MEDLINE, PsycINFO, and Google Scholar was performed to include all primary, therapeutic studies published on the use of cannabis, and cannabis-derived products in orthopedic surgery.

Results

The literature review returned 4292 citations. Thirteen publications were found to meet inclusion criteria. Four randomized controlled trials were evaluated while the remaining studies were of quasi-experimental design.

Conclusion

Research on cannabinoids in orthopedic surgery is mostly of a quasi-experimental nature and is mainly derived from studies where orthopedics was not the primary focus. The overall results demonstrate potential usefulness of cannabinoids as adjunctive analgesics and in mitigating opioid use. However, the current evidence is far from convincing. There is a need to produce rigorous evidence with well-designed randomized controlled trials specific to orthopedic surgery to further establish these effects.

Cannabis and Depression

There is a growing body of evidence pointing to the co-occurrence of cannabis use and depression. There is also some evidence that the use of cannabis may lead to the onset of depression; however, strong evidence points to the inverse association; i.e. that depression may lead to the onset or increase in cannabis use frequency. Observational and epidemiological studies have not indicated a positive long-term effect of cannabis use on the course and outcome of depression. The association between cannabis use and depression may be stronger among men during adolescence and emerging adulthood and stronger in women during midlife. There is an indication for potential genetic correlation contributing to the comorbidity of cannabis dependence and major depression, namely that serotonin (5-HT) may mediate such association and there is also evidence for specific risk alleles for cannabis addiction. There is preclinical evidence that alteration in the endocannabinoid system could potentially benefit patients suffering from depression. However, the issue of using cannabis as an anti-depressant is at an early stage of examination and there is little evidence to support it. Finally, there has been little support to the notion that selective serotonin reuptake inhibitors (SSRIs) may be effective in decreasing depressive symptoms or rates of substance use in adolescents treated for depression and a co-occurring substance use disorder. In conclusion, despite methodological limitations, research in the past decades has broadened our knowledge on the association between cannabis use and depression from epidemiological, neurological, genetic, and pharmacological perspectives.

Control of synaptic transmission and neuronal excitability in the parabrachial nucleus

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The parabrachial nucleus (PB) processes intero- and exteroceptive noxious stimuli.

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Synaptic activity in PB is regulated by GABA_B, µ- and κ-opioid and CB1 receptors.

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GABAergic presynaptic terminals are most potently regulated by these receptors.

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Changes in these pathways may promote PB excitability and pathological conditions.

The parabrachial nucleus (PB) is a hub for aversive behaviors, including those related to pain. We have shown that the expression of chronic pain is causally related to amplified activity of PB neurons, and to changes in synaptic inhibition of these neurons. These findings indicate that regulation of synaptic activity in PB may modulate pain perception and be involved in the pathophysiology of chronic pain. Here, we identify the roles in PB of signaling pathways that modulate synaptic functions. In pharmacologically isolated lateral PB neurons in acute mouse slices we find that baclofen, a GABA_B receptor agonist, suppresses the frequency of miniature inhibitory and excitatory postsynaptic currents (mIPSCs and mEPSC). Activation of µ-opioid peptide receptors with DAMGO had similar suppressive effects on excitatory and inhibitory synapses, while the κ-opioid peptide receptor agonist U-69593 suppressed mIPSC release but had no consistent effects on mEPSCs. Activation of cannabinoid type 1 receptors with WIN 55,212-2 reduced the frequency of both inhibitory and excitatory synaptic events, while the CB1 receptor inverse agonist AM251 had opposite effects on mIPSC and mEPSC frequencies. AM251 increased the frequency of inhibitory events but led to a reduction in excitatory events through a GABA_B mediated mechanism. Although none of the treatments produced a consistent effect on mIPSC or mEPSC amplitudes, baclofen and DAMGO both reliably activated a postsynaptic conductance. These results demonstrate that multiple signaling pathways can alter synaptic transmission and neuronal excitability in PB and provide a basis for investigating the contributions of these systems to the development and maintenance of chronic pain.

The neuropharmacology of cannabinoid receptor ligands in central signaling pathways

The endocannabinoid system is a complex neuronal system involved in a number of biological functions, like attention, anxiety, mood, memory, appetite, reward, and immune responses. It is at the centre of scientific interest, which is driven by therapeutic promise of certain cannabinoid ligands and the changing legalization of herbal cannabis in many countries. The endocannabinoid system is a modulatory system, with endocannabinoids as retrograde neurotransmitters rather than direct neurotransmitters. Neuropharmacology of cannabinoid ligands in the brain can therefore be understood in terms of their modulatory actions through other neurotransmitter systems. The CB₁ receptor is chiefly responsible for effects of endocannabinoids and analogous ligands in the brain. An overview of the neuropharmacology of several cannabinoid receptor ligands, including endocannabinoids, herbal cannabis and synthetic cannabinoid receptor ligands is given in this review. Their mechanism of action at the endocannabinoid system is described, mainly in the brain. In addition, effects of cannabinoid ligands on other neurotransmitter systems will also be described, such as dopamine, serotonin, glutamate, noradrenaline, opioid, and GABA. In light of this, therapeutic potential and adverse effects of cannabinoid receptor ligands will also be discussed.

How do stupendous cannabinoids modulate memory processing via affecting neurotransmitter systems?

In the present study, we wanted to review the role of cannabinoids in learning and memory in animal models, with respect to their interaction effects with six principal neurotransmitters involved in learning and memory including dopamine, glutamate, GABA (γ-aminobutyric acid), serotonin, acetylcholine, and noradrenaline. Cannabinoids induce a wide-range of unpredictable effects on cognitive functions, while their mechanisms are not fully understood. Cannabinoids in different brain regions and in interaction with different neurotransmitters, show diverse responses. Previous findings have shown that cannabinoids agonists and antagonists induce various unpredictable effects such as similar effect, paradoxical effect, or dualistic effect. It should not be forgotten that brain neurotransmitter systems can also play unpredictable roles in mediating cognitive functions. Thus, we aimed to review and discuss the effect of cannabinoids in interaction with neurotransmitters on learning and memory. In addition, we mentioned to the type of interactions between cannabinoids and neurotransmitter systems. We suggested that investigating the type of interactions is a critical neuropharmacological issue that should be considered in future studies.

Acute effects of cannabinoids on symptoms of obsessive-compulsive disorder: A human laboratory study

BACKGROUND

Preclinical data implicate the endocannabinoid system in the pathology underlying obsessive-compulsive disorder (OCD), while survey data have linked OCD symptoms to increased cannabis use. Cannabis products are increasingly marketed as treatments for anxiety and other OCD-related symptoms. Yet, few studies have tested the acute effects of cannabis on psychiatric symptoms in humans.

METHODS

We recruited 14 adults with OCD and prior experience using cannabis to enter a randomized, placebo-controlled, human laboratory study to compare the effects on OCD symptoms of cannabis containing varying concentrations of Δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) on OCD symptoms to placebo. We used a within-subjects design to increase statistical power. Across three laboratory sessions, participants smoked three cannabis varietals in random order: placebo (0% THC/0% CBD); THC (7.0% THC/0.18% CBD); and CBD (0.4% THC/10.4% CBD). We analyzed acute changes in OCD symptoms, state anxiety, cardiovascular measures, and drug-related effects (e.g., euphoria) as a function of varietal.

RESULTS

Twelve participants completed the study. THC increased heart rate, blood pressure, and intoxication compared with CBD and placebo. Self-reported OCD symptoms and anxiety decreased over time in all three conditions. Although OCD symptoms did not vary as a function of cannabis varietal, state anxiety was significantly lower immediately after placebo administration relative to both THC and CBD.

CONCLUSIONS

This is the first placebo-controlled investigation of cannabis in adults with OCD. The data suggest that smoked cannabis, whether containing primarily THC or CBD, has little acute impact on OCD symptoms and yields smaller reductions in anxiety compared to placebo.

VF-13, a chimeric peptide of VD-hemopressin(α) and neuropeptide VF, produces potent antinociception with reduced cannabinoid-related side effects

Pharmacological evidence indicated a functional interaction between neuropeptide FF (NPFF) and cannabinoid systems, and the cannabinoids combined with the NPFF receptor agonist neuropeptide VF (NPVF) produced antinociception without tolerance. In the present study, VF-13, a chimeric peptide containing the pharmacophores of the endogenous cannabinoid peptide VD-hemopressin(α) (VD-Hpα) and NPVF, was synthesized and pharmacologically evaluated. In vitro, VF-13 significantly upregulated the phosphorylated level of extracellular signal-regulated kinase 1/2 (ERK1/2) in CHO cells stably expressing CB1 receptors and inhibited forskolin-induced cAMP accumulation in HEK293 cells stably expressing NPFF₁ or NPFF₂ receptors. Moreover, VF-13 induced neurite outgrowth in Neuro 2A cells via CB1 and NPFF receptors. These results suggest that VF-13 exhibits multifunctional agonism at CB1, NPFF₁ and NPFF₂ receptors in vitro. Interestingly, intracerebroventricular VF-13 produced dose-dependent antinociception in mouse models of tail-flick and carrageenan-induced inflammatory pain via the TRPV1 receptor. In contrast, the reference compound (m)VD-Hpα-NH₂ induced CB1 receptor-mediated supraspinal antinociception. Additionally, subcutaneous injection of (m)VD-Hpα-NH₂ and VF-13 produced significant antinociception in carrageenan-induced inflammatory pain model. In the tetrad assay, our data demonstrated that VF-13 elicited hypothermia, but not catalepsy and hypoactivity after intracerebroventricular injection. Notably, VF-13 produced non-tolerance forming antinociception over 6 days treatment in both acute and inflammatory pain models. Furthermore, VF-13 had no apparent effects on gastrointestinal transit, pentobarbitone-induced sedation, food intake, and motor coordination at the supraspinal level. In summary, VF-13, a novel chimeric peptide of VD-Hpα and NPVF, produced non-tolerance forming antinociception in preclinical pain models with reduced cannabinoid-related side effects.

Personality Traits and Psychotic Proneness Among Chronic Synthetic Cannabinoid Users

OBJECTIVE

Chronic use of synthetic cannabinoids (SCs) has been associated with a wide range of negative consequences for health including psychotic and affective disturbances. Accumulating evidence indicates that cannabinoids use may be a risk factor for schizophrenia, and chronic natural cannabis users score higher than non-users on measures of schizotypal personality traits. However, little is known regarding the personality characteristics of SC users, especially in comparison with recreational cannabis users and healthy individuals. This study aimed to examine the differences in personality characteristics and schizotypy between SC users, regular cannabis users, and non-users and to compare these measures between groups.

METHODS

Forty-two chronic SC users, 39 natural cannabis users, and 47 non-using control participants, without history of mental disorder, or current substance use diagnosis (mean age 26± 4.47 years; 23 females, 105 males), completed the Big-Five Factor Inventory (BFI), the Schizotypal Personality Questionnaire-Brief (SPQ-B), substance use history, rating scales of depression and anxiety, and a demographic questionnaire.

RESULTS

On the BFI, SC users scored higher than natural cannabis users and non-users on neuroticism, but lower on agreeableness and extraversion, and endorsed greater schizotypal symptoms on the SPQ-B. In addition, SC users had lower scores on conscientiousness than non-users, and natural cannabis users were more extroverted than non-users. Higher openness and lower conscientiousness predicted schizotypy for both SC and natural cannabis users. Finally, greater neuroticism predicted schizotypy for natural cannabis users, and introversion predicted schizotypy for non-users.

CONCLUSIONS

These results show that chronic SC users differ from natural cannabis users and non-users on dimensions of specific personality traits and schizotypy that may indicate psychotic proneness.

Synthetic cannabinoid receptor agonists-induced recurrent seizure in elderly patient

Abuse of synthetic cannabinoid receptor agonists (SCRAs) has been associated with young individuals. The abuse of SCRAs is very rare in elderly people, but a few cases highlight the SCRAs-induced side effects. These substances lead to a variety of clinical and psychiatric symptoms including seizures. Here we report recurrent seizures after SCRA abuse by an elderly patient.

Phytocannabinoids in Neurological Diseases: Could They Restore a Physiological GABAergic Transmission?

γ-Aminobutyric acid type A receptors (GABAARs) are the main inhibitory mediators in the central nervous system (CNS). GABAARs are pentameric ligand gated ion channels, and the main subunit composition is usually 2α2βγ, with various isotypes assembled within a set of 19 different subunits. The inhibitory function is mediated by chloride ion movement across the GABAARs, activated by synaptic GABA release, reducing neuronal excitability in the adult CNS. Several studies highlighted the importance of GABA-mediated transmission during neuro-development, and its involvement in different neurological and neurodevelopmental diseases, from anxiety to epilepsy. However, while it is well known how different classes of drugs are able to modulate the GABAARs function (benzodiazepines, barbiturates, neurosteroids, alcohol), up to now little is known about GABAARs and cannabinoids interaction in the CNS. Endocannabinoids and phytocannabinoids are lately emerging as a new class of promising drugs for a wide range of neurological conditions, but their safety as medication, and their mechanisms of action are still to be fully elucidated. In this review, we will focus our attention on two of the most promising molecules (Δ9-tetrahydrocannabinol; Δ9-THC and cannabidiol; CBD) of this new class of drugs and their possible mechanism of action on GABAARs.