MicroRNA let-7d is a target of cannabinoid CB1 receptor and controls cannabinoid signaling

Endocannabinoid signaling and epigenetics modifications in the neurobiology of stress-related disorders

Stress exposure is associated with psychiatric conditions, such as depression, anxiety, and post-traumatic stress disorder (PTSD). It is also a vulnerability factor to developing or reinstating substance use disorder. Stress causes several changes in the neuro-immune-endocrine axis, potentially resulting in prolonged dysfunction and diseases. Changes in several transmitters, including serotonin, dopamine, glutamate, gamma-aminobutyric acid (GABA), glucocorticoids, and cytokines, are associated with psychiatric disorders or behavioral alterations in preclinical studies. Complex and interacting mechanisms make it very difficult to understand the physiopathology of psychiatry conditions; therefore, studying regulatory mechanisms that impact these alterations is a good approach. In the last decades, the impact of stress on biology through epigenetic markers, which directly impact gene expression, is under intense investigation; these mechanisms are associated with behavioral alterations in animal models after stress or drug exposure, for example. The endocannabinoid (eCB) system modulates stress response, reward circuits, and other physiological functions, including hypothalamus-pituitary-adrenal axis activation and immune response. eCBs, for example, act retrogradely at presynaptic neurons, limiting the release of neurotransmitters, a mechanism implicated in the antidepressant and anxiolytic effects after stress. Epigenetic mechanisms can impact the expression of eCB system molecules, which in turn can regulate epigenetic mechanisms. This review will present evidence of how the eCB system and epigenetic mechanisms interact and the consequences of this interaction in modulating behavioral changes after stress exposure in preclinical studies or psychiatric conditions. Moreover, evidence that correlates the involvement of the eCB system and epigenetic mechanisms in drug abuse contexts will be discussed.

Sperm capacitation and transcripts levels are altered by in vitro THC exposure

BACKGROUND

Delta-9-tetrahydrocannabinol (THC) is the primary phytocannabinoid responsible for the psychoactive properties of cannabis and is known to interact with the endocannabinoid system, which is functionally present in the male reproductive system. Since cannabis consumption is the highest among reproductive aged males, the current study aimed to further investigate the effects of THC exposure to phenotypical, physiological, and molecular parameters in sperm. Bull sperm of known fertility were used as a translational model for human sperm and subjected to in vitro treatment with physiologically relevant experimental doses of THC. Sperm parameters, capacitation, apoptosis, and transcript levels were evaluated following treatment.

RESULTS

Motility, morphology, and viability of bovine sperm was unaltered from THC exposure. However, 0.32µM of THC caused an increased proportion of capacitating sperm (p < 0.05) compared to control and vehicle group sperm. Transcriptome analysis revealed that 39 genes were found to be differentially expressed by 0.032µM THC exposure, 196 genes were differentially expressed by 0.32µM THC exposure, and 33 genes were differentially expressed by 3.2µM THC. Secondary analysis reveals pathways involving development, nucleosomes, ribosomes and translation, and cellular metabolism to be significantly enriched.

CONCLUSION

Phytocannabinoid exposure to sperm may adversely affect sperm function by stimulating premature capacitation. These findings also show for the first time that spermatozoal transcripts may be altered by THC exposure. These results add to previous research demonstrating the molecular effects of cannabinoids on sperm and warrant further research into the effects of cannabis on male fertility.

Molecular Insights into Epigenetics and Cannabinoid Receptors

The actions of cannabis are mediated by G protein-coupled receptors that are part of an endogenous cannabinoid system (ECS). ECS consists of the naturally occurring ligands N-arachidonylethanolamine (anandamide) and 2-arachidonoylglycerol (2-AG), their biosynthetic and degradative enzymes, and the CB1 and CB2 cannabinoid receptors. Epigenetics are heritable changes that affect gene expression without changing the DNA sequence, transducing external stimuli in stable alterations of the DNA or chromatin structure. Cannabinoid receptors are crucial candidates for exploring their functions through epigenetic approaches due to their significant roles in health and diseases. Epigenetic changes usually promote alterations in the expression of genes and proteins that can be evaluated by various transcriptomic and proteomic analyses. Despite the exponential growth of new evidence on the critical functions of cannabinoid receptors, much is still unknown regarding the contribution of various genetic and epigenetic factors that regulate cannabinoid receptor gene expression. Recent studies have identified several immediate and long-lasting epigenetic changes, such as DNA methylation, DNA-associated histone proteins, and RNA regulatory networks, in cannabinoid receptor function. Thus, they can offer solutions to many cellular, molecular, and behavioral impairments found after modulation of cannabinoid receptor activities. In this review, we discuss the significant research advances in different epigenetic factors contributing to the regulation of cannabinoid receptors and their functions under both physiological and pathological conditions. Increasing our understanding of the epigenetics of cannabinoid receptors will significantly advance our knowledge and could lead to the identification of novel therapeutic targets and innovative treatment strategies for diseases associated with altered cannabinoid receptor functions.

A Review on the Bioactivity of Cannabinoids on Zebrafish Models: Emphasis on Neurodevelopment

For centuries, the cannabis plant has been used as a source of food, fiber, and medicine. Recently, scientific interest in cannabis has increased considerably, as its bioactive compounds have shown promising potential in the treatment of numerous musculoskeletal and neurological diseases in humans. However, the mechanisms that underlie its possible effects on neurodevelopment and nervous-system functioning remain poorly understood and need to be further investigated. Although the bulk of research on cannabis and cannabinoids is based on in vitro or rodent models, the zebrafish has now emerged as a powerful in vivo model for drug-screening studies and translational research. We here review the available literature on the use of cannabis/cannabinoids in zebrafish, and particularly in zebrafish models of neurological disorders. A critical analysis suggests that zebrafish could serve as an experimental tool for testing the bioactivity of cannabinoids, and they could thus provide important insights into the safety and efficacy of different cannabis-extract-based products. The review showed that zebrafish exhibit similar behaviors to rodents following cannabinoid exposure. The authors stress the importance of analyzing the full spectrum of naturally occurring cannabinoids, rather than just the main ones, THC and CBD, and they offer some pointers on performing behavioral analysis in zebrafish.

WIN55212-2 alleviates acute lung injury by inhibiting macrophage glycolysis through the miR-29b-3p/FOXO3/PFKFB3 axis

BACKGROUND

Acute lung injury (ALI) is a severe organ dysfunction caused by sepsis. WIN55212-2 (WIN) is a cannabinoid receptor agonist. Activation of cannabinoid type 2 receptor can alleviate septic lung injury. Therefore, the effects of WIN on sepsis-related ALI were evaluated.

METHODS

MiR-29b-3p, FOXO3 and PFKFB3 levels, as well as M1 and M2 macrophage markers were assessed by RT-qPCR in MH-S cells after lipopolysaccharide (LPS) and WIN treatment. ChIP and dual luciferase reporter assays determined molecules interactions. Glycolysis-related proteins were evaluated by Western blotting assay. Lactic acid and ATP were also tested. Furthermore, the effect of WIN was tested in sepsis mice model. HE staining evaluated the histopathological changes in mouse lung tissues. The number of inflammatory cells and macrophages, protein concentration and lactic acid content were detected in mouse bronchoalveolar lavage fluid.

RESULTS

We found that WIN suppressed M1 polarization and glycolysis in alveolar macrophages induced by LPS. Moreover, WIN inhibited FOXO3 by up-regulating miR-29b-3p. Furthermore, we verified that FOXO3 induced macrophage M1 polarization and glycolysis through activating PFKFB3. In vivo, WIN alleviated ALI in mice with sepsis.

CONCLUSION

Our results reveal that WIN inhibits macrophage glycolysis through the miR-29b-3p/ FOXO3/PFKFB3 axis, suggesting new therapeutic targets to alleviate sepsis-related ALI.

Inflammation and Nitro-oxidative Stress as Drivers of Endocannabinoid System Aberrations in Mood Disorders and Schizophrenia

The endocannabinoid system (ECS) is composed of the endocannabinoid ligands anandamide (AEA) and 2-arachidonoylgycerol (2-AG), their target cannabinoid receptors (CB₁ and CB₂) and the enzymes involved in their synthesis and metabolism (N-acyltransferase and fatty acid amide hydrolase (FAAH) in the case of AEA and diacylglycerol lipase (DAGL) and monoacylglycerol lipase (MAGL) in the case of 2-AG). The origins of ECS dysfunction in major neuropsychiatric disorders remain to be determined, and this paper explores the possibility that they may be associated with chronically increased nitro-oxidative stress and activated immune-inflammatory pathways, and it examines the mechanisms which might be involved. Inflammation and nitro-oxidative stress are associated with both increased CB₁ expression, via increased activity of the NADPH oxidases NOX4 and NOX1, and increased CNR1 expression and DNA methylation; and CB₂ upregulation via increased pro-inflammatory cytokine levels, binding of the transcription factor Nrf2 to an antioxidant response element in the CNR2 promoter region and the action of miR-139. CB₁ and CB₂ have antagonistic effects on redox signalling, which may result from a miRNA-enabled negative feedback loop. The effects of inflammation and oxidative stress are detailed in respect of AEA and 2-AG levels, via effects on calcium homeostasis and phospholipase A₂ activity; on FAAH activity, via nitrosylation/nitration of functional cysteine and/or tyrosine residues; and on 2-AG activity via effects on MGLL expression and MAGL. Finally, based on these detailed molecular neurobiological mechanisms, it is suggested that cannabidiol and dimethyl fumarate may have therapeutic potential for major depressive disorder, bipolar disorder and schizophrenia.

Epigenetic Regulation of Cannabinoid-Mediated Attenuation of Inflammation and Its Impact on the Use of Cannabinoids to Treat Autoimmune Diseases

Chronic inflammation is considered to be a silent killer because it is the underlying cause of a wide range of clinical disorders, from cardiovascular to neurological diseases, and from cancer to obesity. In addition, there are over 80 different types of debilitating autoimmune diseases for which there are no cure. Currently, the drugs that are available to suppress chronic inflammation are either ineffective or overtly suppress the inflammation, thereby causing increased susceptibility to infections and cancer. Thus, the development of a new class of drugs that can suppress chronic inflammation is imperative. Cannabinoids are a group of compounds produced in the body (endocannabinoids) or found in cannabis (phytocannabinoids) that act through cannabinoid receptors and various other receptors expressed widely in the brain and immune system. In the last decade, cannabinoids have been well established experimentally to mediate anti-inflammatory properties. Research has shown that they suppress inflammation through multiple pathways, including apoptosis and inducing immunosuppressive T regulatory cells (Tregs) and myeloid-derived suppressor cells (MDSCs). Interestingly, cannabinoids also mediate epigenetic alterations in genes that regulate inflammation. In the current review, we highlight how the epigenetic modulations caused by cannabinoids lead to the suppression of inflammation and help identify novel pathways that can be used to target autoimmune diseases.

Biogenesis, physiological functions and potential applications of extracellular vesicles in substance use disorders

Substance use disorder (SUD) is a growing health problem that affects several millions of people worldwide, resulting in negative socioeconomic impacts and increased health care costs. Emerging evidence suggests that extracellular vesicles (EVs) play a crucial role in SUD pathogenesis. EVs, including exosomes and microvesicles, are membrane-encapsulated particles that are released into the extracellular space by most types of cells. EVs are important players in mediating cell-to-cell communication through transfer of cargo such as proteins, lipids and nucleic acids. The EV cargo can alter the status of recipient cells, thereby contributing to both physiological and pathological processes; some of these play critical roles in SUD. Although the functions of EVs under several pathological conditions have been extensively reviewed, EV functions and potential applications in SUD remain less studied. In this review, we provide an overview of the current knowledge of the role of EVs in SUD, including alcohol, cocaine, heroin, marijuana, nicotine and opiate abuse. The review will focus on the biogenesis and cargo composition of EVs as well as the potential use of EVs as biomarkers of SUD or therapeutic targets in SUD.

Role of microRNAs in the pathophysiology of addiction

Addiction is a chronic and relapsing brain disorder characterized by compulsive seeking despite adverse consequences. There are both heritable and epigenetic mechanisms underlying drug addiction. Emerging evidence suggests that non-coding RNAs (ncRNAs) such as microRNAs (miRNAs), long non-coding RNAs, and circular RNAs regulate synaptic plasticity and related behaviors caused by substances of abuse. These ncRNAs modify gene expression and may contribute to the behavioral phenotypes of addiction. Among the ncRNAs, the most widely researched and impactful are miRNAs. The goal in this systematic review is to provide a detailed account of recent research involving the role of miRNAs in addiction. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Small Molecule-RNA Interactions RNA in Disease and Development > RNA in Disease.

Role of Extracellular Vesicles in Substance Abuse and HIV-Related Neurological Pathologies

Extracellular vesicles (EVs) are a broad, heterogeneous class of membranous lipid-bilayer vesicles that facilitate intercellular communication throughout the body. As important carriers of various types of cargo, including proteins, lipids, DNA fragments, and a variety of small noncoding RNAs, including miRNAs, mRNAs, and siRNAs, EVs may play an important role in the development of addiction and other neurological pathologies, particularly those related to HIV. In this review, we summarize the findings of EV studies in the context of methamphetamine (METH), cocaine, nicotine, opioid, and alcohol use disorders, highlighting important EV cargoes that may contribute to addiction. Additionally, as HIV and substance abuse are often comorbid, we discuss the potential role of EVs in the intersection of substance abuse and HIV. Taken together, the studies presented in this comprehensive review shed light on the potential role of EVs in the exacerbation of substance use and HIV. As a subject of growing interest, EVs may continue to provide information about mechanisms and pathogenesis in substance use disorders and CNS pathologies, perhaps allowing for exploration into potential therapeutic options.

The Epigenetics of the Endocannabinoid System

The endocannabinoid system (ES) is a cell-signalling system widely distributed in biological tissues that includes endogenous ligands, receptors, and biosynthetic and hydrolysing machineries. The impairment of the ES has been associated to several pathological conditions like behavioural, neurological, or metabolic disorders and infertility, suggesting that the modulation of this system may be critical for the maintenance of health status and disease treatment. Lifestyle and environmental factors can exert long-term effects on gene expression without any change in the nucleotide sequence of DNA, affecting health maintenance and influencing both disease load and resistance. This potentially reversible "epigenetic" modulation of gene expression occurs through the chemical modification of DNA and histone protein tails or the specific production of regulatory non-coding RNA (ncRNA). Recent findings demonstrate the epigenetic modulation of the ES in biological tissues; in the same way, endocannabinoids, phytocannabinoids, and cannabinoid receptor agonists and antagonists induce widespread or gene-specific epigenetic changes with the possibility of trans-generational epigenetic inheritance in the offspring explained by the transmission of deregulated epigenetic marks in the gametes. Therefore, this review provides an update on the epigenetics of the ES, with particular attention on the emerging role in reproduction and fertility.

Cannabis Sativa Revisited-Crosstalk between microRNA Expression, Inflammation, Oxidative Stress, and Endocannabinoid Response System in Critically Ill Patients with Sepsis

Critically ill patients with sepsis require a multidisciplinary approach, as this situation implies multiorgan distress, with most of the bodily biochemical and cellular systems being affected by the condition. Moreover, sepsis is characterized by a multitude of biochemical interactions and by dynamic changes of the immune system. At the moment, there is a gap in our understanding of the cellular, genetic, and molecular mechanisms involved in sepsis. One of the systems intensely studied in recent years is the endocannabinoid signaling pathway, as light was shed over a series of important interactions of cannabinoid receptors with biochemical pathways, specifically for sepsis. Furthermore, a series of important implications on inflammation and the immune system that are induced by the activity of cannabinoid receptors stimulated by the delta-9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD) have been noticed. One of the most important is their ability to reduce the biosynthesis of pro-inflammatory mediators and the modulation of immune mechanisms. Different studies have reported that cannabinoids can reduce oxidative stress at mitochondrial and cellular levels. The aim of this review paper was to present, in detail, the important mechanisms modulated by the endocannabinoid signaling pathway, as well as of the molecular and cellular links it has with sepsis. At the same time, we wish to present the possible implications of cannabinoids in the most important biological pathways involved in sepsis, such as inflammation, redox activity, immune system, and epigenetic expression.

WIN55,212-2-Induced Expression of Mir-29b1 Favours the Suppression of Osteosarcoma Cell Migration in a SPARC-Independent Manner

WIN55,212-2 (WIN) is a synthetic agonist of cannabinoid receptors that displays promising antitumour properties. The aim of this study is to demonstrate that WIN is able to block the migratory ability of osteosarcoma cells and characterize the mechanisms involved. Using wound healing assay and zymography, we showed that WIN affects cell migration and reduces the activity of the metalloproteases MMP2 and MMP9. This effect seemed to be independent of secreted protein acidic and rich in cysteine (SPARC), a matricellular protein involved in tissue remodeling and extracellular matrix deposition. SPARC release was indeed prevented by WIN, and SPARC silencing by RNA interference did not influence the effect of the cannabinoid on cell migration. WIN also increased the release of extracellular vesicles and dramatically upregulated miR-29b1, a key miRNA that modulates cell proliferation and migration. Interestingly, reduced cell migration was observed in stably miR-29b1-transfected cells, similarly to WIN-treated cells. Finally, we show the absence of SPARC in the extracellular vesicles released by osteosarcoma cells and no changes in SPARC level in miR-29b1 overexpressing cells. Overall, these findings suggest that WIN markedly affects cell migration, dependently on miR-29b1 and independently of SPARC, and can thus be considered as a potential innovative therapeutic agent in the treatment of osteosarcoma.

Noncoding RNAs in development and teratology, with focus on effects of cannabis, cocaine, nicotine, and ethanol

Completion of the Human Genome Project has led to the identification of a large number of transcription start sites that are not paired with protein-coding genes, supporting the growing recognition of the abundance of encoded nonprotein-coding RNAs (ncRNAs) and their importance for speciation and species-specific development. Present in both plants and animals, ncRNAs vary in size, function, primary sequence, and secondary structure. While microRNAs (miRNAs) are the best known, there are a number of other ncRNAs (long[er] nonprotein-coding RNA, pseudogenes, circular RNAs, and so on) that have been shown to play an important role in the development either directly or via networks of proteins and other ncRNAs, including modulating the impact of miRNAs. Furthermore, these ncRNAs and their developmental regulatory networks are sensitive to teratogens such as ethanol, cannabis, cocaine, and nicotine. A better understanding of the developmental role of ncRNAs and their capacity to mediate teratogenesis is a necessary step in efforts to minimize the long-term consequences of developmental exposures to drugs-of-abuse. Moreover, with increasing awareness of the prevalence of polydrug use, experimental models will need to incorporate more complex drug exposure paradigms into meaningful assessments of developmental ncRNA function.

Maternal high-fat diet impairs leptin signaling and up-regulates type-1 cannabinoid receptor with sex-specific epigenetic changes in the hypothalamus of newborn rats

Maternal nutritional imbalances trigger developmental adaptations involving early epigenetic mechanisms associated with adult chronic disease. Maternal high-fat (HF) diet promotes obesity and hypothalamic leptin resistance in male rat offspring at weaning and adulthood. Leptin resistance is associated with over activation of the endocannabinoid system (ECS). The ECS mainly consists of endocannabinoids derived from n-6 fatty acids and cannabinoid receptors (CB1 coded by Cnr1 and CB2 coded by Cnr2). The CB1 activation in hypothalamus stimulates feeding and appetite for fat while CB2 activation seems to play an immunomodulatory role. We demonstrated that maternal HF diet increases hypothalamic CB1 in male offspring while increases CB2 in female offspring at birth, prior to obesity development. However, the molecular mechanisms behind these changes remain unexplored. We hypothesized that maternal HF diet would down-regulate leptin signaling and up-regulate Cnr1 mRNA levels in the hypothalamus of the offspring at birth, associated with sex-specific changes in epigenetic markers and sex steroid signaling. To test our hypothesis, we used progenitor female rats that received control diet (C, 9% fat) or isocaloric high-fat diet (HF, 28% fat) from 8 weeks before mating until delivery. Blood, hypothalamus and carcass from C and HF male and female offspring were collected for biochemical and molecular analyses at birth. Maternal HF diet down-regulated the transcriptional factor STAT3 in the hypothalamus of male and female offspring, but induced hypoleptinemia only in males and decreased phosphorylated STAT3 only in female offspring. Because leptin acts through STAT3 pathway to inhibit central ECS, our results suggest that leptin pathway impairment might contribute to increased levels of Crn1 mRNA in hypothalamus of both sex offspring. Besides, maternal HF diet increased the histone acetylation percentage of Cnr1 promoter in male offspring and increased the androgen receptor binding to the Cnr1 promoter, which can contribute to higher expression of Cnr1 in newborn HF offspring. Maternal HF diet increased plasma n6 to n3 fatty acid ratio in male offspring, which is an important risk factor to metabolic diseases and might indicate an over activation of endocannabinoid signaling. Thus, although maternal HF diet programs a similar phenotype in adult offspring of both sexes (obesity, hyperphagia and higher preference for fat), here we showed that molecular mechanisms involving leptin signaling, ECS, epigenetic markers and sex hormone signaling were modified prior to obesity development and can differ between newborn male and female offspring. These observations may provide molecular insights into sex-specific targets for anti-obesity therapies.

Synthetic Cannabinoids Influence the Invasion of Glioblastoma Cell Lines in a Cell- and Receptor-Dependent Manner

The current treatment of glioblastoma is not sufficient, since they are heterogeneous and often resistant to chemotherapy. Earlier studies demonstrated effects of specific cannabinoid receptor (CB) agonists on the invasiveness of glioblastoma cell lines, but the exact mechanism remained unclear. Three human glioblastoma cell lines were treated with synthetic CB ligands. The effect of cannabinoids on microRNAs (miRs), Akt, and on the expression of proliferation and apoptosis markers were analyzed. Furthermore, in a model of organotypic hippocampal slice cultures cannabinoid mediated changes in the invasiveness were assessed. MicroRNAs and the activation of Akt which are related to cell migration, apoptosis, and proliferation were evaluated and found not to be associated with changes in the invasiveness after treatment with CB ligands. Also proliferation and/or apoptosis were not altered after treatment. The effects of cannabinoids on invasiveness could be blocked by the application of receptor antagonists and are likely mediated via CB₁/CB₂. In conclusion, our results suggest that cannabinoids can influence glioblastoma cell invasion in a receptor and cell type specific manner that is independent of proliferation and apoptosis. Thus, cannabinoids can potentially be used in the future as an addition to current therapy.

No association between G1359A CB1 polymorphisms and pain in young northeastern Mexicans

AIM

Recent studies show an association between the endocannabinoid system and pain. In this study, we analyzed the association between two CNR1 gene polymorphisms and pain perception in a northeast Mexican population.

METHODS

Genotypic and allelic frequencies were obtained for both polymorphisms. Pain threshold, tolerance and perception were measured using the cold pressor task.

RESULTS

No significant association between the polymorphisms and pain perception was found (p > 0.05).

CONCLUSION

Genotypic and allelic frequencies for both polymorphisms were reported for the first time in a Mexican population; however, our results suggest that there is not a significant association between these and pain.

Zebrafish models relevant to studying central opioid and endocannabinoid systems

The endocannabinoid and opioid systems are two interplaying neurotransmitter systems that modulate drug abuse, anxiety, pain, cognition, neurogenesis and immune activity. Although they are involved in such critical functions, our understanding of endocannabinoid and opioid physiology remains limited, necessitating further studies, novel models and new model organisms in this field. Zebrafish (Danio rerio) is rapidly emerging as one of the most effective translational models in neuroscience and biological psychiatry. Due to their high physiological and genetic homology to humans, zebrafish may be effectively used to study the endocannabinoid and opioid systems. Here, we discuss current models used to target the endocannabinoid and opioid systems in zebrafish, and their potential use in future translational research and high-throughput drug screening. Emphasizing the high degree of conservation of the endocannabinoid and opioid systems in zebrafish and mammals, we suggest zebrafish as an excellent model organism to study these systems and to search for the new drugs and therapies targeting their evolutionarily conserved mechanisms.

Epigenetic mechanisms associated with addiction-related behavioural effects of nicotine and/or cocaine: implication of the endocannabinoid system

The addictive use of nicotine (NC) and cocaine (COC) continues to be a major public health problem, and their combined use has been reported, particularly during adolescence. In neural plasticity, commonly induced by NC and COC, as well as behavioural plasticity related to the use of these two drugs, the involvement of epigenetic mechanisms, in which the reversible regulation of gene expression occurs independently of the DNA sequence, has recently been reported. Furthermore, on the basis of intense interactions with the target neurotransmitter systems, the endocannabinoid (ECB) system has been considered pivotal for eliciting the effects of NC or COC. The combined use of marijuana with NC and/or COC has also been reported. This article presents the addiction-related behavioural effects of NC and/or COC, based on the common behavioural/neural plasticity and combined use of NC/COC, and reviews the interacting role of the ECB system. The epigenetic processes inseparable from the effects of NC and/or COC (i.e. DNA methylation, histone modifications and alterations in microRNAs) and the putative therapeutic involvement of the ECB system at the epigenetic level are also discussed.

Potential Role of Extracellular Vesicles in the Pathophysiology of Drug Addiction

Extracellular vesicles (EVs) are small vesicles secreted by cells and are known to carry sub-cellular components including microRNA, proteins, and lipids. Due to their ability to transport cargo between cells, EVs have been identified as important regulators of various pathophysiological conditions and can therefore influence treatment outcomes. In particular, the significance of microRNAs in EV-mediated cell-cell communication is well-documented. While the influence of EVs and the cargo delivered by EVs has been extensively reviewed in other neurological disorders, the available literature on the potential role of EVs in the pathophysiology of drug addiction has not been reviewed. Hence, in this article, the known effects of commonly abused drugs (ethanol, nicotine, opiates, cocaine, and cannabinoids) on EV secretion have been reviewed. In addition, the potential role of drugs of abuse in affecting the delivery of EV-packaged microRNAs, and the subsequent impact on neuronal health and continued drug dependence, has been discussed.

Cannabinoids Modulate Neuronal Activity and Cancer by CB1 and CB2 Receptor-Independent Mechanisms

Cannabinoids include the active constituents of Cannabis or are molecules that mimic the structure and/or function of these Cannabis-derived molecules. Cannabinoids produce many of their cellular and organ system effects by interacting with the well-characterized CB1 and CB2 receptors. However, it has become clear that not all effects of cannabinoid drugs are attributable to their interaction with CB1 and CB2 receptors. Evidence now demonstrates that cannabinoid agents produce effects by modulating activity of the entire array of cellular macromolecules targeted by other drug classes, including: other receptor types; ion channels; transporters; enzymes, and protein- and non-protein cellular structures. This review summarizes evidence for these interactions in the CNS and in cancer, and is organized according to the cellular targets involved. The CNS represents a well-studied area and cancer is emerging in terms of understanding mechanisms by which cannabinoids modulate their activity. Considering the CNS and cancer together allow identification of non-cannabinoid receptor targets that are shared and divergent in both systems. This comparative approach allows the identified targets to be compared and contrasted, suggesting potential new areas of investigation. It also provides insight into the diverse sources of efficacy employed by this interesting class of drugs. Obtaining a comprehensive understanding of the diverse mechanisms of cannabinoid action may lead to the design and development of therapeutic agents with greater efficacy and specificity for their cellular targets.

Epigenetic Interactions between Alcohol and Cannabinergic Effects: Focus on Histone Modification and DNA Methylation

Epigenetic studies have led to a more profound understanding of the mechanisms involved in chronic conditions. In the case of alcohol addiction, according to the National Institute on Alcohol Abuse and Alcoholism, 16 million adults suffer from Alcohol Use Disorders (AUDs). Even though therapeutic interventions like behavioral therapy and medications to prevent relapse are currently available, no robust cure exists, which stems from the lack of understanding the mechanisms of action of alcohol and the lack of development of precision medicine approaches to treat AUDs. Another common group of addictive substance, cannabinoids, have been studied extensively to reveal they work through cannabinoid receptors. Therapeutic applications have been found for the cannabinoids and a deeper understanding of the endocannabinoid system has been gained over the years. Recent reports of cannabinergic mechanisms in AUDs has opened an exciting realm of research that seeks to elucidate the molecular mechanisms of alcohol-induced end organ diseases and hopefully provide insight into new therapeutic strategies for the treatment of AUDs. To date, several epigenetic mechanisms have been associated with alcohol and cannabinoids independently. Therefore, the scope of this review is to compile the most recent literature regarding alcohol and cannabinoids in terms of a possible epigenetic connection between the endocannabinoid system and alcohol effects. First, we will provide an overview of epigenetics, followed by an overview of alcohol and epigenetic mechanisms with an emphasis on histone modifications and DNA methylations. Then, we will provide an overview of cannabinoids and epigenetic mechanisms. Lastly, we will discuss evidence of interactions between alcohol and cannabinergic pathways and possible insights into the novel epigenetic mechanisms underlying alcohol-cannabinergic pathway activity. Finalizing the review will be a discussion of future directions and therapeutic applications.