The dynamic nature of type 1 cannabinoid receptor (CB(1) ) gene transcription

Correlations of the CNR1 Gene with Personality Traits in Women with Alcohol Use Disorder

Alcohol use disorder (AUD) is a significant issue affecting women, with severe consequences for society, the economy, and most importantly, health. Both personality and alcohol use disorders are phenotypically very complex, and elucidating their shared heritability is a challenge for medical genetics. Therefore, our study investigated the correlations between the microsatellite polymorphism (AAT)n of the Cannabinoid Receptor 1 (CNR1) gene and personality traits in women with AUD. The study group included 187 female subjects. Of these, 93 were diagnosed with alcohol use disorder, and 94 were controls. Repeat length polymorphism of microsatellite regions (AAT)n in the CNR1 gene was identified with PCR. All participants were assessed with the Mini-International Neuropsychiatric Interview and completed the NEO Five-Factor and State-Trait Anxiety Inventories. In the group of AUD subjects, significantly fewer (AAT)n repeats were present when compared with controls (p = 0.0380). While comparing the alcohol use disorder subjects (AUD) and the controls, we observed significantly higher scores on the STAI trait (p < 0.00001) and state scales (p = 0.0001) and on the NEO Five-Factor Inventory Neuroticism (p < 0.00001) and Openness (p = 0.0237; insignificant after Bonferroni correction) scales. Significantly lower results were obtained on the NEO-FFI Extraversion (p = 0.00003), Agreeability (p < 0.00001) and Conscientiousness (p < 0.00001) scales by the AUD subjects when compared to controls. There was no statistically significant Pearson's linear correlation between the number of (AAT)n repeats in the CNR1 gene and the STAI and NEO Five-Factor Inventory scores in the group of AUD subjects. In contrast, Pearson's linear correlation analysis in controls showed a positive correlation between the number of the (AAT)n repeats and the STAI state scale (r = 0.184; p = 0.011; insignificant after Bonferroni correction) and a negative correlation with the NEO-FFI Openness scale (r = -0.241; p = 0.001). Interestingly, our study provided data on two separate complex issues, i.e., (1) the association of (AAT)n CNR1 repeats with the AUD in females; (2) the correlation of (AAT)n CNR1 repeats with anxiety as a state and Openness in non-alcohol dependent subjects. In conclusion, our study provided a plethora of valuable data for improving our understanding of alcohol use disorder and anxiety.

Effects of acute Δ9-tetrahydrocannabinol on behavior and the endocannabinoid system in HIV-1 Tat transgenic female and male mice

Cannabis use is highly prevalent especially among people living with HIV (PLWH). Activation of the anti-inflammatory and neuroprotective endocannabinoid system by phytocannabinoids, i.e. Δ9-tetrahydrocannabinol (THC), has been proposed to reduce HIV symptoms. However, THC's effects on HIV-related memory deficits are unclear. Using HIV-1 Tat transgenic mice, the current study investigates acute THC effects on various behavioral outcomes and the endocannabinoid system. For the rodent tetrad model, THC doses (1, 3, 10 mg/kg) induced known antinociceptive effects, with Tat induction increasing antinociceptive THC effects at 3 and 10 mg/kg doses. Only minor or no effects were noted for acute THC on body temperature, locomotor activity, and coordination. Increased anxiety-like behavior was found for females compared to males, but acute THC had no effect on anxiety. Object recognition memory was diminished by acute THC in Tat(-) females but not Tat(+) females, without affecting males. The endocannabinoid system and related lipids were not affected by acute THC, except for THC-induced decreases in CB1R protein expression levels in the spinal cord of Tat(-) mice. Female sex and Tat induction was associated with elevated 2-AG, AEA, AA, CB1R, CB2R, FAAH and/or MAGL expression in various brain regions. Further, AEA levels in the prefrontal cortex of Tat(+) females were negatively associated with object recognition memory. Overall, findings indicate that acute THC exerts differential effects on antinociception and memory, dependent on sex and HIV Tat expression, potentially in relation to an altered endocannabinoid system, which may be of relevance in view of potential cannabis-based treatment options for PLWH.

Exploring the therapeutic potential of natural compounds modulating the endocannabinoid system in various diseases and disorders: review

Cannabinoid receptors, endogenous cannabinoids (endocannabinoids), and the enzymes involved in the biosynthesis and degradation of the endocannabinoids make up the endocannabinoid system (ECS). The components of the ECS are proven to modulate a vast bulk of various physiological and pathological processes due to their abundance throughout the human body. Such discoveries have attracted the researchers' attention and emerged as a potential therapeutical target for the treatment of various diseases. In the present article, we reviewed the discoveries of natural compounds, herbs, herbs formula, and their therapeutic properties in various diseases and disorders by modulating the ECS. We also summarize the molecular mechanisms through which these compounds elicit their properties by interacting with the ECS based on the existing findings. Our study provides the insight into the use of natural compounds that modulate ECS in various diseases and disorders, which in turn may facilitate future studies exploiting natural lead compounds as novel frameworks for designing more effective and safer therapeutics.

Cannabinoid Receptor mRNA Expression in Central and Peripheral Tissues in a Rodent Model of Peritonitis

Introduction: Our laboratory investigates changes in the respiratory pattern during systemic inflammation in various rodent models. The endogenous cannabinoid system (ECS) regulates cytokine production and mitigates inflammation. Inflammation not only affects cannabinoid (CB) 1 and CB2 receptor gene expression (Cnr1 and Cnr2), but also increases the predictability of the ventilatory pattern. Objectives: Our primary objective was to track ventilatory pattern variability and transcription of Cnr1 and Cnr2 mRNA, and of Il1b, Il6, and tumor necrosis factor-alpha (Tnfa) mRNAs at multiple time points in central and peripheral tissues during systemic inflammation induced by peritonitis. Methods: In male Sprague Dawley rats (n=24), we caused peritonitis by implanting a fibrin clot containing either 0 or 25×106 Escherichia coli intraperitoneally. We recorded breathing with whole-animal plethysmography at baseline and 1 h before euthanasia. We euthanized the rats at 3, 6, or 12 h after inoculation and harvested the pons, medulla, lung, and heart for gene expression analysis. Results: With peritonitis, Cnr1 mRNA more than Cnr2 mRNA was correlated to Il1b, Il6, and Tnfa mRNAs in medulla, pons, and lung and changed oppositely in the pons, medulla, and lung. These changes were associated with increased predictability of ventilatory pattern. Specifically, nonlinear complexity index correlated with increased Cnr1 mRNA in the pons and medulla, and coefficient of variation for cycle duration correlated with Cnr1 and Cnr2 mRNAs in the lung. Conclusion: The mRNAs for ECS receptors varied with time during the central and peripheral inflammatory response to peritonitis. These changes occurred in the brainstem, which contains the network that generates breathing pattern and thus, may participate in ventilatory pattern changes during systemic inflammation.

Endocannabinoid system and epigenetics in spermatogenesis and testicular cancer

In mammals, male germ cell development starts during fetal life and is carried out in postnatal life with the formation of sperms. Spermatogenesis is the complex and highly orderly process during which a group of germ stem cells is set at birth, starts to differentiate at puberty. It proceeds through several stages: proliferation, differentiation, and morphogenesis and it is strictly regulated by a complex network of hormonal, autocrine and paracrine factors and it is associated with a unique epigenetic program. Altered epigenetic mechanisms or inability to respond to these factors can impair the correct process of germ development leading to reproductive disorders and/or testicular germ cell cancer. Among factors regulating spermatogenesis an emerging role is played by the endocannabinoid system (ECS). ECS is a complex system comprising endogenous cannabinoids (eCBs), their synthetic and degrading enzymes, and cannabinoid receptors. Mammalian male germ cells have a complete and active ECS which is modulated during spermatogenesis and that crucially regulates processes such as germ cell differentiation and sperm functions. Recently, cannabinoid receptor signaling has been reported to induce epigenetic modifications such as DNA methylation, histone modifications and miRNA expression. Epigenetic modifications may also affect the expression and function of ECS elements, highlighting the establishment of a complex mutual interaction. Here, we describe the developmental origin and differentiation of male germ cells and testicular germ cell tumors (TGCTs) focusing on the interplay between ECS and epigenetic mechanisms involved in these processes.

Frequent Low-Dose Δ9-Tetrahydrocannabinol in Adolescence Disrupts Microglia Homeostasis and Disables Responses to Microbial Infection and Social Stress in Young Adulthood

BACKGROUND

During adolescence, microglia are actively involved in neocortical maturation while concomitantly undergoing profound phenotypic changes. Because the teenage years are also a time of experimentation with cannabis, we evaluated whether adolescent exposure to the drug's psychotropic constituent, Δ9-tetrahydrocannabinol (THC), might persistently alter microglia function.

METHODS

We administered THC (5 mg/kg, intraperitoneal) once daily to male and female mice from postnatal day (PND) 30 to PND44 and examined the transcriptome of purified microglia in adult animals (PND70 and PND120) under baseline conditions or following either of two interventions known to recruit microglia: lipopolysaccharide injection and repeated social defeat. We used high-dimensional mass cytometry by time-of-flight to map brain immune cell populations after lipopolysaccharide challenge.

RESULTS

Adolescent THC exposure produced in mice of both sexes a state of microglial dyshomeostasis that persisted until young adulthood (PND70) but receded with further aging (PND120). Key features of this state included broad alterations in genes involved in microglia homeostasis and innate immunity along with marked impairments in the responses to lipopolysaccharide- and repeated social defeat-induced psychosocial stress. The endocannabinoid system was also dysfunctional. The effects of THC were prevented by coadministration of either a global CB1 receptor inverse agonist or a peripheral CB1 neutral antagonist and were not replicated when THC was administered in young adulthood (PND70-84).

CONCLUSIONS

Daily low-intensity CB1 receptor activation by THC during adolescence may disable critical functions served by microglia until young adulthood with potentially wide-ranging consequences for brain and mental health.

Lack of Association between (AAT)n Polymorphism of the CNR1 Gene Encoding the Cannabinoid Receptor (CB1) and Patient’s Quality of Life

Genetic factors may predispose persons to decreased pain excitability. One of the interesting modulators affecting pain perception may be polymorphisms of the cannabinoid receptor type 1 (CNR1) gene. In this study, we examined the association between three-nucleotide repeats (AAT) polymorphism located in the 3′UTR non-translational region of CNR1 and the patient’s quality of life after total hip arthroplasty. Our study examined the degree of pain sensation, hip function, and the patient’s performance at defined intervals after elective hip replacement due to degenerative changes. The study included 198 patients (128 women and 70 men). The average age was 67 years. PCR genotyping assay was used to identify the (AAT)n triplet repeat polymorphism in the CNR1 gene. The (AAT)n repeat number was determined by sequencing using a standard sequencing protocol. Our study found no statistically significant association between the degree of pain, hip function, and the change in the degree of disability and the (AAT)n polymorphism in the CNR1 gene, no statistically significant correlations between clinical symptoms, the patient’s age, and the number of AAT repeats, no association between the length of the allele and the degree of pain, hip function, and the change in disability.

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.

Psychosocial stress and cannabinoid drugs affect acetylation of α-tubulin (K40) and gene expression in the prefrontal cortex of adult mice

The dynamics of neuronal microtubules are essential for brain plasticity. Vesicular transport and synaptic transmission, additionally, requires acetylation of α-tubulin, and aberrant tubulin acetylation and neurobiological deficits are associated. Prolonged exposure to a stressor or consumption of drugs of abuse, like marihuana, lead to neurological changes and psychotic disorders. Here, we studied the effect of psychosocial stress and the administration of cannabinoid receptor type 1 drugs on α-tubulin acetylation in different brain regions of mice. We found significantly decreased tubulin acetylation in the prefrontal cortex in stressed mice. The impact of cannabinoid drugs on stress-induced microtubule disturbance was investigated by administration of the cannabinoid receptor agonist WIN55,212–2 and/or antagonist rimonabant. In both, control and stressed mice, the administration of WIN55,212–2 slightly increased the tubulin acetylation in the prefrontal cortex whereas administration of rimonabant acted antagonistically indicating a cannabinoid receptor type 1 mediated effect. The analysis of gene expression in the prefrontal cortex showed a consistent expression of ApoE attributable to either psychosocial stress or administration of the cannabinoid agonist. Additionally, ApoE expression inversely correlated with acetylated tubulin levels when comparing controls and stressed mice treated with WIN55,212–2 whereas rimonabant treatment showed the opposite.

Yin and yang of cannabinoid CB1 receptor: CB1 deletion in immune cells causes exacerbation while deletion in non-immune cells attenuates obesity

While blockade of cannabinoid receptor 1 (CB1) has been shown to attenuate diet-induced obesity (DIO), its relative role in different cell types has not been tested. The current study investigated the role of CB1 in immune vs non-immune cells during DIO by generating radiation-induced bone marrow chimeric mice that expressed functional CB1 in all cells except the immune cells or expressed CB1 only in immune cells. CB1^−/− recipient hosts were resistant to DIO, indicating that CB1 in non-immune cells is necessary for induction of DIO. Interestingly, chimeras with CB1^−/− in immune cells showed exacerbation in DIO combined with infiltration of bone-marrow-derived macrophages to the brain and visceral adipose tissue, elevated food intake, and increased glucose intolerance. These results demonstrate the opposing role of CB1 in hematopoietic versus non-hematopoietic cells during DIO and suggests that targeting immune CB1 receptors provides a new pathway to ameliorate obesity and related metabolic disorders.

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Cannabinoid Receptor 1 (CB1), and not CB2, regulates diet-induced obesity (DIO)

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CB1 deficiency in non-immune cell types promotes DIO resistance

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CB1 deficiency in immune cells exacerbates DIO disease phenotype

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CB1 activation in immune cells is a potential therapeutic target for DIO attenuation

The cannabinoid receptors system in horses: Tissue distribution and cellular identification in skin

BACKGROUND

The endocannabinoid system (ECS) is composed of cannabinoid receptors type 1 (CBR1) and type 2 (CBR2), cannabinoid-based ligands (endogenous chemically synthesized phytocannabinoids), and endogenous enzymes controlling their concentrations. Cannabinoid receptors (CBRs) have been identified in invertebrates and in almost all vertebrate species in the central and peripheral nervous system as well as in immune cells, where they control neuroimmune homeostasis. In humans, rodents, dogs, and cats, CBRs expression has been confirmed in the skin, and their expression and tissue distribution become disordered in pathological conditions. Cannabinoid receptors may be a possible therapeutic target in skin diseases.

OBJECTIVES

To characterize the distribution and cellular expression of CBRs in the skin of horses under normal conditions.

ANIMALS

Fifteen healthy horses.

METHODS

Using full-thickness skin punch biopsy samples, skin-derived primary epidermal keratinocytes and dermal-derived cells, we performed analysis of Cnr1 and Cnr2 genes using real-time PCR and CBR1 and CBR2 protein expression by confocal microscopy and Western blotting.

RESULTS

Normal equine skin, including equine epidermal keratinocytes and dermal fibroblast-like cells, all exhibited constant gene and protein expression of CBRs.

CONCLUSIONS AND CLINICAL IMPORTANCE

Our results represent a starting point for developing and translating new veterinary medicine-based pharmacotherapies using ECS as a possible target.

Molecular Alterations of the Endocannabinoid System in Psychiatric Disorders

The therapeutic benefits of the current medications for patients with psychiatric disorders contrast with a great variety of adverse effects. The endocannabinoid system (ECS) components have gained high interest as potential new targets for treating psychiatry diseases because of their neuromodulator role, which is essential to understanding the regulation of many brain functions. This article reviewed the molecular alterations in ECS occurring in different psychiatric conditions. The methods used to identify alterations in the ECS were also described. We used a translational approach. The animal models reproducing some behavioral and/or neurochemical aspects of psychiatric disorders and the molecular alterations in clinical studies in post-mortem brain tissue or peripheral tissues were analyzed. This article reviewed the most relevant ECS changes in prevalent psychiatric diseases such as mood disorders, schizophrenia, autism, attentional deficit, eating disorders (ED), and addiction. The review concludes that clinical research studies are urgently needed for two different purposes: (1) To identify alterations of the ECS components potentially useful as new biomarkers relating to a specific disease or condition, and (2) to design new therapeutic targets based on the specific alterations found to improve the pharmacological treatment in psychiatry.

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.

Differential expression of the neuronal CB1 cannabinoid receptor in the hippocampus of male Ts65Dn Down syndrome mouse model

Down syndrome (DS) or Trisomy 21 is the most common genetic cause of mental retardation with severe learning and memory deficits. DS is due to the complete or partial triplication of human chromosome 21 (HSA21) triggering gene overexpression and protein synthesis alterations responsible for a plethora of mental and physical phenotypes. Among the diverse brain target systems that affect hippocampal-dependent learning and memory deficit impairments in DS, the upregulation of the endocannabinoid system (ECS), and notably the overexpression of the cannabinoid type-1 receptor (CB1), seems to play a major role. Combining various protein and gene expression targeted approaches using western blot, qRT-PCR and FISH techniques, we investigated the expression pattern of ECS components in the hippocampus (HPC) of male Ts65Dn mice. Among all the molecules that constitute the ECS, we found that the expression of the CB1 is altered in the HPC of Ts65Dn mice. CB1 distribution is differentially segregated between the dorsal and ventral part of the HPC and within the different cell populations that compose the HPC. CB1 expression is upregulated in GABAergic neurons of Ts65Dn mice whereas it is downregulated in glutamatergic neurons. These results highlight a complex regulation of the CB1 encoding gene (Cnr1) in Ts65Dn mice that could open new therapeutic solutions for this syndrome.

Cannabis-Induced Malignant Catatonia: A Medical Emergency and Review of Prior Case Series

Few case reports of catatonia associated with cannabis use are reported. Here, we describe a case of a 35-year-old African American male who developed malignant catatonia following heavy cannabis use. The patient was brought to the emergency department (ED) for altered mental status, hypertension, and erratic behavior. Before his ED presentation, he was smoking cannabis in heavy amounts, confirmed by positive urine toxicology in ED. Initial lab results showed leukocytosis, elevated creatine phosphokinase (CPK) levels. Head CT scans without contrast, including cerebrospinal fluid (CSF) analysis, were nonsignificant. In ED, the patient was agitated, combative, mute, and rigid. He was sedated using 2 mg of intramuscular (IM) midazolam. Psychiatric consultation services suspected catatonia, and the patient scored 12 points on Bush-Francis Catatonia Rating Scale (BFCRS). Although the patient’s symptoms responded to 2 mg of IM lorazepam, the patient later relapsed, became tachycardic with blood pressure fluctuations, and his repeat BFCRS score was 18. At this point, the patient was diagnosed as having malignant catatonia, and his lorazepam dosage was increased up to 6 mg IM per day. After a few days of waxing and waning of his symptoms, he finally started to show constant improvement and gradually reduced his symptoms. Our case highlights the first-ever reported case of malignant catatonia associated with cannabis use.

A novel bioassay for quantification of surface Cannabinoid receptor 1 expression

The cannabinoid receptor type 1 (CB1) plays critical roles in multiple physiological processes such as pain perception, brain development and body temperature regulation. Mutations on this gene (CNR1), results in altered functionality and/or biosynthesis such as reduced membrane expression, changes in mRNA stability or changes in downstream signaling that act as triggers for diseases such as obesity, Parkinson’s, Huntington’s, among others; thus, it is considered as a potential pharmacological target. To date, multiple quantification methods have been employed to determine how these mutations affect receptor expression and localization; however, they present serious disadvantages that may arise quantifying errors. Here, we describe a sensitive bioassay to quantify receptor surface expression; in this bioassay the Gaussia Luciferase (GLuc) was fused to the extracellular portion of the CB1. The GLuc activity was assessed by coelenterazine addition to the medium followed by immediate readout. Based on GLuc activity assay, we show that the GLuc signals corelate with CB1 localization, besides, we showed the assay’s functionality and reliability by comparing its results with those generated by previously reported mutations on the CNR1 gene and by using flow cytometry to determine the cell surface receptor expression. Detection of membrane-bound CB1, and potentially other GPCRs, is able to quickly screen for receptor levels and help to understand the effect of clinically relevant mutations or polymorphisms.

Cannabinoid Receptors: An Update on Cell Signaling, Pathophysiological Roles and Therapeutic Opportunities in Neurological, Cardiovascular, and Inflammatory Diseases

The identification of the human cannabinoid receptors and their roles in health and disease, has been one of the most significant biochemical and pharmacological advancements to have occurred in the past few decades. In spite of the major strides made in furthering endocannabinoid research, therapeutic exploitation of the endocannabinoid system has often been a challenging task. An impaired endocannabinoid tone often manifests as changes in expression and/or functions of type 1 and/or type 2 cannabinoid receptors. It becomes important to understand how alterations in cannabinoid receptor cellular signaling can lead to disruptions in major physiological and biological functions, as they are often associated with the pathogenesis of several neurological, cardiovascular, metabolic, and inflammatory diseases. This review focusses mostly on the pathophysiological roles of type 1 and type 2 cannabinoid receptors, and it attempts to integrate both cellular and physiological functions of the cannabinoid receptors. Apart from an updated review of pre-clinical and clinical studies, the adequacy/inadequacy of cannabinoid-based therapeutics in various pathological conditions is also highlighted. Finally, alternative strategies to modulate endocannabinoid tone, and future directions are also emphasized.

Epigenetics and the endocannabinoid system signaling: An intricate interplay modulating neurodevelopment

The endocannabinoid (eCB) system is a complex system comprising endogenous cannabinoids (eCBs), their synthesis and degradation enzymes, and cannabinoid receptors. These elements crucially regulate several biological processes during neurodevelopment, such as proliferation, differentiation, and migration. Recently, eCBs were also reported to have an epigenetic action on genes that play key functions in the neurotransmitter signaling, consequently regulating their expression. In turn, epigenetic modifications (e.g. DNA methylation, histone modifications) may also modulate the function of eCB system's elements. For example, the expression of the cnr gene in the central nervous system may be epigenetically regulated (e.g. DNA methylation, histone modifications), thus altering the function of the cannabinoid receptor type-1 (CB₁R). Considering the importance of the eCB system during neurodevelopment, it is thus reasonable to expect that alterations in this interaction between the eCB system and epigenetic modifications may give rise to neurodevelopmental disorders. Here, we review key concepts related to the regulation of neuronal function by the eCB system and the different types of epigenetic modifications. In particular, we focus on the mechanisms involved in the intricate interplay between both signaling systems and how they control cell fate during neurodevelopment. Noteworthy, such mechanistic understanding assumes high relevance considering the implications of the dysregulation of key neurogenic processes towards the onset of neurodevelopment-related disorders. Moreover, considering the increasing popularity of cannabis and its synthetic derivatives among young adults, it becomes of utmost importance to understand how exogenous cannabinoids may epigenetically impact neurodevelopment.

Cannabinoid receptor CNR1 expression and DNA methylation in human prefrontal cortex, hippocampus and caudate in brain development and schizophrenia

Beyond being one the most widely used psychoactive drugs in the world, cannabis has been identified as an environmental risk factor for psychosis. Though the relationship between cannabis use and psychiatric disorders remains controversial, consistent association between early adolescent cannabis use and the subsequent risk of psychosis suggested adolescence may be a particularly vulnerable period. Previous findings on gene by environment interactions indicated that cannabis use may only increase the risk for psychosis in the subjects who have a specific genetic vulnerability. The type 1 cannabinoid receptor (CB1), encoded by the CNR1 gene, is a key component of the endocannabinoid system. As the primary endocannabinoid receptor in the brain, CB1 is the main molecular target of the endocannabinoid ligand, as well as tetrahydrocannabinol (THC), the principal psychoactive ingredient of cannabis. In this study, we have examined mRNA expression and DNA methylation of CNR1 in human prefrontal cortex (PFC), hippocampus, and caudate samples. The expression of CNR1 is higher in fetal PFC and hippocampus, then drops down dramatically after birth. The lifespan trajectory of CNR1 expression in the DLPFC differentially correlated with age by allelic variation at rs4680, a functional polymorphism in the COMT gene. Compared with COMT methionine¹⁵⁸ carriers, Caucasian carriers of the COMT valine¹⁵⁸ allele have a stronger negative correlation between the expression of CNR1 in DLPFC and age. In contrast, the methylation level of cg02498983, which is negatively correlated with the expression of CNR1 in PFC, showed the strongest positive correlation with age in PFC of Caucasian carriers of COMT valine¹⁵⁸. Additionally, we have observed decreased mRNA expression of CNR1 in the DLPFC of patients with schizophrenia. Further analysis revealed a positive eQTL SNP, rs806368, which predicted the expression of a novel transcript of CNR1 in human DLPFC, hippocampus and caudate. This SNP has been associated with addiction and other psychiatric disorders. THC or ethanol are each significantly associated with dysregulated expression of CNR1 in the PFC of patients with affective disorder, and the expression of CNR1 is significantly upregulated in the PFC of schizophrenia patients who completed suicide. Our results support previous studies that have implicated the endocannabinoid system in the pathology of schizophrenia and provided additional insight into the mechanism of increasing risk for schizophrenia in the adolescent cannabis users.

Arachidonyl-2'-chloroethylamide (ACEA), a synthetic agonist of cannabinoid receptor, increases CB1R gene expression and reduces dyskinesias in a rat model of Parkinson's disease

l-Dopa is the most effective drug used for Parkinson's disease (PD), but after long-term treatment, the vast majority of PD patients develop abnormal involuntary movements (AIMs) termed l-Dopa-induced dyskinesia (LID). Cannabinoid receptors in the basal ganglia can modulate motor functions, but their role in the treatment of LID is controversial. Therefore, the aim of this study is to evaluate the motor behavior and mRNA expression of the cannabinoid receptor-1 (CB₁R), encoded by the Cnr1 gene, in the striatum and globus pallidus of a 6-hydroxydopamine rat model of PD. The evaluated rats had 6-hydroxydopamine-induced injury, LID, and LID treated with arachidonyl-2'-chloroethylamide (ACEA), a cannabinoid receptor agonist. Contralateral turns and AIMs were recorded to assess motor behavior. Gene expression was quantified by reverse transcription coupled with quantitative polymerase chain reaction using TaqMan probes. Behavioral evaluations demonstrated that dyskinetic rats treated with ACEA had a significant reduction in AIMs compared to the dyskinetic group. The expression of CB₁R mRNA was significantly decreased in the 6-hydroxydopamine-injured and dyskinetic rats, compared to intact rats. The striata of dyskinetic rats treated with ACEA exhibited highly significant increases in CB₁R mRNA expression. Contrary to results in the striatum, a lower CB₁R expression was observed in globus pallidus from dyskinetic ACEA-treated group. In summary, significant differences in mRNA expression of CB₁R were found between the evaluated groups of rats, suggesting the occurrence of compensatory mechanisms that may result in the ACEA-mediated reduction of dyskinesias in a rat model of PD.

The Endocannabinoid System and Synthetic Cannabinoids in Preclinical Models of Seizure and Epilepsy

Cannabinoids are compounds that are structurally and/or functionally related to the primary psychoactive constituent of Cannabis sativa, [INCREMENT]-tetrahydrocannabinol (THC). Cannabinoids can be divided into three broad categories: endogenous cannabinoids, plant-derived cannabinoids, and synthetic cannabinoids (SCs). Recently, there has been an unprecedented surge of interest into the pharmacological and medicinal properties of cannabinoids for the treatment of epilepsies. This surge has been stimulated by an ongoing shift in societal opinions about cannabinoid-based medicines and evidence that cannabidiol, a nonintoxicating plant cannabinoid, has demonstrable anticonvulsant activity in children with treatment-refractory epilepsy. The major receptors of the endogenous cannabinoid system (ECS)-the type 1 and 2 cannabinoid receptors (CB1R, CB2R)-have critical roles in the modulation of neurotransmitter release and inflammation, respectively; so, it is not surprising therefore that the ECS is being considered as a target for the treatment of epilepsy. SCs were developed as potential new drug candidates and tool compounds for studying the ECS. Beyond the plant cannabinoids, an extensive research effort is underway to determine whether SCs that directly target CB1R, CB2R, or the enzymes that breakdown endogenous cannabinoids have anticonvulsant effects in preclinical rodent models of epilepsy and seizure. This research demonstrates that many SCs do reduce seizure severity in rodent models and may have both positive and negative pharmacodynamic and pharmacokinetic interactions with clinically used antiepilepsy drugs. Here, we provide a comprehensive review of the preclinical evidence for and against SC modulation of seizure and discuss the important questions that need to be addressed in future studies.

Histone methyltransferase G9a diminishes expression of cannabinoid CB1 receptors in primary sensory neurons in neuropathic pain

Type 1 cannabinoid receptors (CB₁Rs) are expressed in the dorsal root ganglion (DRG) and contribute to the analgesic effect of cannabinoids. However, the epigenetic mechanism regulating the expression of CB₁Rs in neuropathic pain is unknown. G9a (encoded by the Ehmt2 gene), a histone 3 at lysine 9 methyltransferase, is a key chromatin regulator responsible for gene silencing. In this study, we determined G9a's role in regulating CB₁R expression in the DRG and in CB₁R-mediated analgesic effects in an animal model of neuropathic pain. We show that nerve injury profoundly reduced mRNA levels of CB₁Rs but increased the expression of CB₂ receptors in the rat DRG. ChIP results indicated increased enrichment of histone 3 at lysine 9 dimethylation, a G9a-catalyzed repressive histone mark, at the promoter regions of the CB₁R genes. G9a inhibition in nerve-injured rats not only up-regulated the CB₁R expression level in the DRG but also potentiated the analgesic effect of a CB₁R agonist on nerve injury-induced pain hypersensitivity. Furthermore, in mice lacking Ehmt2 in DRG neurons, nerve injury failed to reduce CB₁R expression in the DRG and to decrease the analgesic effect of the CB₁R agonist. Moreover, nerve injury diminished the inhibitory effect of the CB₁R agonist on synaptic glutamate release from primary afferent nerves to spinal cord dorsal horn neurons in WT mice but not in mice lacking Ehmt2 in DRG neurons. Our findings reveal that nerve injury diminishes the analgesic effect of CB₁R agonists through G9a-mediated CB₁R down-regulation in primary sensory neurons.

The cannabinoid agonist WIN-2 affects acquisition but not consolidation of a spatial information in training and retraining processes: Relation with transcriptional regulation of the endocannabinoid system?

The endocannabinoid system is capable of modulating multiple physiological brain functions including learning and memory. Moreover, there is evidence that the processes of acquisition and consolidation have distinct biological basis. We used the cannabinoid agonist WIN 55,212-2 (WIN-2) to investigate whether chronic CB1 activation affects acquisition and consolidation differently by evaluating gene expression in the hippocampus (HIP) and prefrontal cortex (PFC). Swiss mice were treated with WIN-2 (2 mg/kg) and submitted to the Morris water maze to evaluate different aspects of memory. We observed short-term memory impairment in acquisition of the spatial task while consolidation remained unchanged. In the PFC, animals that received WIN-2 prior to the task exhibited increased expression of the 2-AG synthesis enzyme diacylglycerol lipase and decreased levels of the degradation enzyme monoacylglycerol lipase, while mice that were treated after the task for the evaluation of consolidation exhibited the opposite profile. With respect to genes related to AEA metabolism, no correlation between the molecular and behavioral data could be established. In this sense, the cognitive impairment in the acquisition promoted by WIN-2 treatment may be related to a possible increase in the concentration of 2-AG in the PFC. Overall, this study confirms the relevance of the endocannabinoid system in the modulation of cognitive processes. A better understanding of the mechanisms underlying endocannabinoids roles in cognition could provide guidance for the development of treatments to reduce the cognitive deficits caused by drug abuse.

Disruption of an enhancer associated with addictive behaviour within the cannabinoid receptor-1 gene suggests a possible role in alcohol intake, cannabinoid response and anxiety-related behaviour

The cannabinoid-1 receptor (CB₁) plays a critical role in a number of biological processes including nutrient intake, addiction and anxiety-related behaviour. Numerous studies have shown that expression of the gene encoding CB1 (CNR1) is highly dynamic with changes in the tissue specific expression of CNR1 associated with brain homeostasis and disease progression. However, little is known of the mechanisms regulating this dynamic expression. To gain a better understanding of the genomic mechanisms modulating the expression of CNR1 in health and disease we characterised the role of a highly conserved regulatory sequence (ECR1) in CNR1 intron 2 that contained a polymorphism in linkage disequilibrium with disease associated SNPs. We used CRISPR/CAS9 technology to disrupt ECR1 within the mouse genome. Disruption of ECR1 significantly reduced CNR1 expression in the hippocampus but not in the hypothalamus. These mice also displayed an altered sex-specific anxiety-related behavioural profile (open field test), reduced ethanol intake and a reduced hypothermic response following CB₁ agonism. However, no significant changes in feeding patterns were detected. These data suggest that, whilst not all of the expression of CNR1 is modulated by ECR1, this highly conserved enhancer is required for appropriate physiological responses to a number of stimuli. The combination of comparative genomics and CRISPR/CAS9 disruption used in our study to determine the functional effects of genetic and epigenetic changes on the activity of tissue-specific regulatory elements at the CNR1 locus represent an important first step in gaining a mechanistic understanding of cannabinoid regulatory pharmacogenetics.

G1359A Polymorphism of the Cannabinoid Receptor 1 Is Not Associated with Overweight and Dyslipidemia in Young Northeastern Mexicans

There is extensive evidence to believe that the endocannabinoid system plays an important role in energy homeostasis through a variety of mechanisms. This study aimed to analyze the association between polymorphism rs12720071 of the cannabinoid type 1 receptor (CNR1) gene with dyslipidemia and overweight in young, healthy Mexicans. The association was analyzed with a logistic regression model and expressed as odds ratio (OR). A total of 148 individuals agreed to participate. Overall, the serum concentrations of lipids were found to be in the normal range. However, females presented higher levels of cholesterol and low-density lipoprotein (LDL) than males [probability value (p) = <0.05]. In addition, females presented higher risk of being overweight (BMI: >25) [OR = 3.57; 95% confidence interval (CI): 1.05-12.20; p = 0.04], than males. Our results suggest that this polymorphism could influence BMI in young females.

Gene expression signature in brain regions exposed to long-term psychosocial stress following acute challenge with cannabinoid drugs

Repeated exposure to life stressors can overwhelm the body's capacity to restore homeostasis and result in severe negative consequences. Cannabinoid CB₁ receptors are highly expressed in the Central Nervous System (CNS) and regulate both glucocorticoid signalling and neurotransmitter release. In rodents, WIN55212.2 is a full agonist at the cannabinoid receptor type-1, while Rimonabant is a potent and selective cannabinoid inverse agonist at this receptor. This study aims to investigate the effect of long-term psychosocial stress following acute challenge with cannabinoid drugs on gene expression in distinct brain regions; this is done by employing digital multiplexed gene expression analysis. We found that repeated stress increased cortical mRNA levels of dopamine receptor D2, while the expression of neuregulin-1 decreased in both the prefrontal cortex and cerebellum. Further, we found that the acute injection of the agonist WIN55212.2 reduced striatal levels of dopamine receptor D2, while the use of inverse agonist Rimonabant acted in the opposite direction. The analysis of the interaction between the drugs and repeated stress revealed that defeat mice treated with WIN55212.2 showed lower expression of a set of myelin-related genes, as did the expression of SRY-box 10 and dopamine receptors-D1 and -D2 in the prefrontal cortex when compared to vehicle. In addition, in the hippocampus of stressed mice treated with WIN55212.2, we found an elevated expression of oligodendrocyte transcription factor-1, -2 and zinc finger protein 488 when compared to vehicle. In comparison to vehicle, an increase in 2',3'-Cyclic nucleotide 3'-phosphodiesterase and oligodendrocyte transcription factor-1 occurred in the cerebellum of stressed animals treated with the agonist. Moreover, treatment with Rimonabant under the influence of stress induced an overexpression of a set of myelin-related genes in the prefrontal cortex when compared to WIN-treated animals. In conclusion, repeated stress interfered with the dopaminergic system in the prefrontal cortex. We demonstrated that the expression of dopamine receptor D2 in the striatum was mediated by the CB₁ receptor. Stressed mice exposed to either WIN55212.2 or Rimonabant displayed pronounced deficits in CNS myelination. In addition, the pharmacological blockage of CB₁ receptor in stressed mice deregulated the expression of dopamine receptors and might lead to dysfunctions in dopamine metabolism.

Ontogeny and programming of the fetal temporal cortical endocannabinoid system by moderate maternal nutrient reduction in baboons (Papio spp.)

Poor nutrition during pregnancy is a worldwide public health problem. Maternal nutrient reduction (MNR) is associated with maternal and fetal stress and a sex-dependent decrease in nonhuman primate (NHP) cognitive performance. Early life stress potentiates epileptogenesis in a sex-specific manner, and temporal lobe (TL) epilepsy is associated with neurocognitive disorders. The endogenous cannabinoid system (ECS) demonstrates remarkable developmental changes and plays a key role in aging-related diseases (e.g., dementia). Baboons have been studied as a natural model of epilepsy and express all ECS system components. We therefore evaluated baboon fetal temporal cortex ECS ontogenic and MNR-dependent changes. At 120 days gestational age (dGA) (term 185 days), maternal, fetal, and placental morphometry were similar between control and MNR pregnancies. MNR maternal weight gain was decreased compared with controls at 165 dGA independent of fetal sex. In male fetuses, expression of ECS synthesizing and degrading enzymes was gestational age-dependent, with the exception of fatty acid amide hydrolase (FAAH). MNR had a sex-specific effect on the protein expression of CB1R during development: CB1R protein expression was decreased in fetal temporal cortex of male fetuses at 120 and 140 dGA. Our data reveal that the MNR has sex-specific effects on temporal cortical expression of the ECS in baboon offspring and shows vulnerability of ECS in male fetuses during gestation.

Cannabinoid receptor 2 deficiency exacerbates inflammation and neutrophil recruitment

Cannabinoid receptor (CB)₂ is an immune cell–localized GPCR that has been hypothesized to regulate the magnitude of inflammatory responses. However, there is currently no consensus as to the mechanism by which CB₂ mediates its anti-inflammatory effects in vivo. To address this question, we employed a murine dorsal air pouch model with wild-type and CB₂^−/− 8–12-wk-old female and male C57BL/6 mice and found that acute neutrophil and lymphocyte antigen 6 complex, locus C^hi monocyte recruitment in response to Zymosan was significantly enhanced in CB₂^−/− mice. Additionally, levels of matrix metalloproteinase 9 and the chemokines C-C motif chemokine ligand (CCL)2, CCL4, and C-X-C motif chemokine ligand 10 in CB₂^−/− pouch exudates were elevated at earlier time points. Importantly, using mixed bone marrow chimeras, we revealed that the proinflammatory phenotype in CB₂^−/− mice is neutrophil-intrinsic rather than stromal cell–dependent. Indeed, neutrophils isolated from CB₂^−/− mice exhibited an enhanced migration-related transcriptional profile and increased adhesive phenotype, and treatment of human neutrophils with a CB₂ agonist blocked their endothelial transmigration. Overall, we have demonstrated that CB₂ plays a nonredundant role during acute neutrophil mobilization to sites of inflammation and, as such, it could represent a therapeutic target for the development of novel anti-inflammatory compounds to treat inflammatory human diseases.—Kapellos, T. S., Taylor, L., Feuerborn, A., Valaris, S., Hussain, M. T., Rainger, G. E., Greaves, D. R., Iqbal, A. J. Cannabinoid receptor 2 deficiency exacerbates inflammation and neutrophil recruitment.

Germinated soy germ extract ameliorates obesity through beige fat activation

Obesity is a worldwide public health concern requiring safe and effective strategies. Recent studies suggest that bioactive compounds from soybeans have beneficial effects on weight loss and reducing fat accumulation. However, despite the biochemical and nutritional changes during germination, the biological effects of germinated soy germ have not been fully investigated. In this article, germinated soy germ extract (GSGE) was evaluated as a potential treatment option for obesity using 3T3-L1 pre-adipocyte and high-fat diet (HFD)-induced obese mice. In vitro studies demonstrated that GSGE suppressed the differentiation of 3T3-L1 cells into mature adipocytes, along with reductions in lipid accumulation and lipid droplet formation. In vivo studies also showed that a daily dose of 1 mg kg-1 of GSGE reduced weight gain, adipocyte area, serum triglyceride, and LDL-cholesterol in HFD-fed mice. The GSGE treatment promoted browning, which was associated with increased UCP1 expression in vitro and in vivo. In addition, GSGE treatment induced beige fat activation by upregulation of lipolysis and beta-oxidation. Furthermore, gene and protein expression levels of endocannabinoid system-related factors such as NAPE-PLD, FAAH, DAGL-α, and CB2 were altered along with browning and beige fat activation by GSGE. The present study indicates that GSGE effectively inhibits lipid accumulation and promotes beige fat transition and activation. Therefore, we suggest that GSGE treatment could be a promising strategy for the prevention of obesity by promoting weight loss, reducing fat accumulation, and improving obesity-related metabolic disorders.

Some Prospective Alternatives for Treating Pain: The Endocannabinoid System and Its Putative Receptors GPR18 and GPR55

Background: Marijuana extracts (cannabinoids) have been used for several millennia for pain treatment. Regarding the site of action, cannabinoids are highly promiscuous molecules, but only two cannabinoid receptors (CB₁ and CB₂) have been deeply studied and classified. Thus, therapeutic actions, side effects and pharmacological targets for cannabinoids have been explained based on the pharmacology of cannabinoid CB₁/CB₂ receptors. However, the accumulation of confusing and sometimes contradictory results suggests the existence of other cannabinoid receptors. Different orphan proteins (e.g., GPR18, GPR55, GPR119, etc.) have been proposed as putative cannabinoid receptors. According to their expression, GPR18 and GPR55 could be involved in sensory transmission and pain integration.

Methods: This article reviews select relevant information about the potential role of GPR18 and GPR55 in the pathophysiology of pain.

Results: This work summarized novel data supporting that, besides cannabinoid CB₁ and CB₂ receptors, GPR18 and GPR55 may be useful for pain treatment.

Conclusion: There is evidence to support an antinociceptive role for GPR18 and GPR55.

Countering the Modern Metabolic Disease Rampage With Ancestral Endocannabinoid System Alignment

When primitive vertebrates evolved from ancestral members of the animal kingdom and acquired complex locomotive and neurological toolsets, a constant supply of energy became necessary for their continued survival. To help fulfill this need, the endocannabinoid (eCB) system transformed drastically with the addition of the cannabinoid-1 receptor (CB1R) to its gene repertoire. This established an eCB/CB1R signaling mechanism responsible for governing the whole organism's energy balance, with its activation triggering a shift toward energy intake and storage in the brain and the peripheral organs (i.e., liver and adipose). Although this function was of primal importance for humans during their pre-historic existence as hunter-gatherers, it became expendable following the successive lifestyle shifts of the Agricultural and Industrial Revolutions. Modernization of the world has further increased food availability and decreased energy expenditure, thus shifting the eCB/CB1R system into a state of hyperactive deregulated signaling that contributes to the 21st century metabolic disease pandemic. Studies from the literature supporting this perspective come from a variety of disciplines, including biochemistry, human medicine, evolutionary/comparative biology, anthropology, and developmental biology. Consideration of both biological and cultural evolution justifies the design of improved pharmacological treatments for obesity and Type 2 diabetes (T2D) that focus on peripheral CB1R antagonism. Blockade of peripheral CB1Rs, which universally promote energy conservation across the vertebrate lineage, represents an evolutionary medicine strategy for clinical management of present-day metabolic disorders.

Central adiponectin induces trabecular bone mass partly through epigenetic downregulation of cannabinoid receptor CB1

Central adiponectin (APN) in either the globular (gAPN) or full-length forms decreases sympathetic tone and increases trabecular bone mass in mice through the hypothalamus. It is known that cannabinoid type-1 (CB1) receptors are expressed in the hypothalamic ventromedial nucleus and participate in energy metabolism by controlling sympathetic activity. However, whether central APN could influence endocannabinoid signaling through CB1 receptor to regulate bone metabolism has not been characterized. Here we demonstrate that gAPN downregulated CB1 expression in embryonic mouse hypothalamus N1 cells in vitro. gAPN intracerebroventricular (icv) infusions also decreased hypothalamic CB1 expression and bone formation parameters in APN-knockout (APN-KO) and wild-type mice. Most importantly, mice pretreated with icv infusions with the CB1 receptor agonist arachidonyl-2'-chloroethylamine or antagonist rimonabant attenuated or enhanced respectively central APN induction of bone formation. We then investigated whether epigenetic signaling mechanisms were involved in the downregulation of hypothalamic CB1 expression by gAPN. We found gAPN enhanced expression levels of various histone deacetylases (HDACs), especially HDAC5. Furthermore, chromatin immunoprecipitation assays revealed HDAC5 bound to the transcriptional start site transcription start site 2 region of the CB1 promoter. In summary, our study identified a possible novel central APN-HDAC5-CB1 signaling mechanism that promotes peripheral bone formation through epigenetic regulation of hypothalamic CB1 expression.

Sex difference in brain CB1 receptor availability in man

The endocannabinoid system (ECS) has a widespread neuromodulatory function in the central nervous system and is involved in important aspects of brain function including brain development, cortical rhythms, plasticity, reward, and stress sensitivity. Many of these effects are mediated via the cannabinoid CB1 receptor (CB1R) subtype. Animal studies convincingly show an interaction between the ECS and sex hormones, as well as a sex difference of higher brain CB1R in males. Human in vivo studies of sex difference have yielded discrepant findings. Gender differences in CB1R availability were investigated in vivo in 11 male and 11 female healthy volunteers using a specific CB1R tracer [¹⁸F]FMPEP-d2 and positron emission tomography (PET). Regional [¹⁸F]FMPEP-d2 distribution volume was used as a proxy for CB1R availability. In addition, we explored whether CB1R availability is linked to neuropsychological functioning. Relative to females, CB1R availability was on average 41% higher in males (p = 0.002) with a regionally specific effect larger in the posterior cingulate and retrosplenial cortices (p = 0.001). Inter-subject variability in CB1R availability was similar in both groups. Voxel-based analyses revealed an inverse association between CB1R availability and visuospatial working memory task performance in both groups (p < 0.001). A CB1R sex difference with a large effect size was observed and should be considered in the design of CB1R-related studies on neuropsychiatric disorders. The behavioural correlates and clinical significance of this difference remain to be further elucidated, but our studies suggest an association between CB1R availability and working memory.

Structural and Functional Interaction of Δ9-Tetrahydrocannabinol with Liver Fatty Acid Binding Protein (FABP1)

Although serum Δ⁹-tetrahydrocannabinol (Δ⁹-THC) undergoes rapid hepatic clearance and metabolism, almost nothing is known regarding the mechanism(s) whereby this highly lipophilic phytocannabinoid is transported for metabolism/excretion. A novel NBD-arachidonoylethanolamide (NBD-AEA) fluorescence displacement assay showed that liver fatty acid binding protein (FABP1), the major hepatic endocannabinoid (EC) binding protein, binds the first major metabolite of Δ⁹-THC (Δ⁹-THC-OH) as well as Δ⁹-THC itself. Circular dichroism (CD) confirmed that not only Δ⁹-THC and Δ⁹-THC-OH but also downstream metabolites Δ⁹-THC-COOH and Δ⁹-THC-CO-glucuronide directly interact with FABP1. Δ⁹-THC and metabolite interaction differentially altered the FABP1 secondary structure, increasing total α-helix (all), decreasing total β-sheet (Δ⁹-THC-COOH, Δ⁹-THC-CO-glucuronide), increasing turns (Δ⁹-THC-OH, Δ⁹-THC-COOH, Δ⁹-THC-CO-glucuronide), and decreasing unordered structure (Δ⁹-THC, Δ⁹-THC-OH). Cultured primary hepatocytes from wild-type (WT) mice took up and converted Δ⁹-THC to the above metabolites. Fabp1 gene ablation (LKO) dramatically increased hepatocyte accumulation of Δ⁹-THC and even more so its primary metabolites Δ⁹-THC-OH and Δ⁹-THC-COOH. Concomitantly, rtPCR and Western blotting indicated that LKO significantly increased Δ⁹-THC's ability to regulate downstream nuclear receptor transcription of genes important in both EC ( Napepld > Daglb > Dagla, Naaa, Cnr1) and lipid ( Cpt1A > Fasn, FATP4) metabolism. Taken together, the data indicated that FABP1 may play important roles in Δ⁹-THC uptake and elimination as well as Δ⁹-THC induction of genes regulating hepatic EC levels and downstream targets in lipid metabolism.

Disruption of the gonadal endocannabinoid system in zebrafish exposed to diisononyl phthalate

DiNP (Di-isononyl phthalate) has been recently introduced as DEHP (Bis (2-ethylhexyl) phthalate) substitute and due to its chemical properties, DiNP is commonly used in a large variety of plastic items. The endocannabinoid system (ECS) is a lipid signaling system involved in a plethora of physiological pathways including the control of the reproductive and metabolic processes. In this study, the effects of DiNP on the ECS of zebrafish (male and female) gonads were analyzed. Adult zebrafish were chronically exposed for 21 days via water to 3 environmentally relevant concentrations of DiNP (42 μg/L; 4.2 μg/L; 0.42 μg/L). In females, the Gonadosomatic Index (GSI) and the number of fertilized eggs were reduced by the lowest concentration of DiNP tested. The levels of two endocannabinoids, Anandamide (AEA) and 2-Arachidonoylglycerol (2-AG), were not affected, while a reduction of the N-oleoyl-ethanolamine (OEA) level was observed. Transcriptional changes were reported in relation to genes coding for the ECS receptors and the enzymes involved in the ECS pathway. DiNP exposure in males reduced the GSI as well as changed the levels of endocannabinoids. Moreover, DiNP treatment induced significative changes in the genes coding for the ECS receptors and enzymes, and significantly increased the activity of the fatty acid amide hydrolase (FAAH). In summary, in zebrafish, exposure to environmentally relevant concentrations of DiNP disrupted the ECS and affected reproduction in a gender specific manner.

Targeted inhibition of the type 2 cannabinoid receptor is a novel approach to reduce renal fibrosis

The cannabinoid receptor type 2 (CB2) is a G protein-coupled seven transmembrane receptor that transmits endogenous cannabinoid signaling. The role of CB2 in the pathogenesis of kidney injury and fibrosis remains poorly understood. Here we demonstrate that CB2 was induced, predominantly in kidney tubular epithelium, in various models of kidney disease induced by unilateral ureteral obstruction, adriamycin or ischemia/reperfusion injury. In vitro, forced expression of CB2 or treatment with a CB2 agonist was sufficient to trigger matrix gene expression, whereas knockdown of CB2 by siRNA abolished transforming growth factor-β1-induced signaling and fibrogenic responses in kidney tubular cells. CB2 also mediated fibroblasts and macrophage activation in vitro. Mice with genetic ablation of CB2 were protected against kidney injury after ureteral obstruction, validating a pathogenic role of CB2 in renal fibrosis in vivo. By using in silico screening and medicinal chemistry modifications, we discovered a novel compound, XL-001, that bound to CB2 with high affinity and selectivity and acted as an inverse agonist. Incubation with XL-001 inhibited in a dose-dependent fashion the fibrogenic response induced by CB2 overexpression, CB2 agonist or transforming growth factor-β1. In vivo, intraperitoneal injections of XL-001 ameliorated kidney injury, fibrosis and inflammation in both the obstruction and ischemia/reperfusion models. Delayed administration of XL-001 was also effective in ameliorating kidney fibrosis and inflammation. Thus, CB2 is a pathogenic mediator in kidney fibrosis and targeted inhibition with the novel inverse agonist XL-001 may provide a strategy in the fight against fibrotic kidney diseases.

Genetic and pharmacological regulation of the endocannabinoid CB1 receptor in Duchenne muscular dystrophy

The endocannabinoid system refers to a widespread signaling system and its alteration is implicated in a growing number of human diseases. However, the potential role of endocannabinoids in skeletal muscle disorders remains unknown. Here we report the role of the endocannabinoid CB1 receptors in Duchenne's muscular dystrophy. In murine and human models, CB1 transcripts show the highest degree of expression at disease onset, and then decline overtime. Similar changes are observed for PAX7, a key regulator of muscle stem cells. Bioinformatics and biochemical analysis reveal that PAX7 binds and upregulates the CB1 gene in dystrophic more than in healthy muscles. Rimonabant, an antagonist of CB1, promotes human satellite cell differentiation in vitro, increases the number of regenerated myofibers, and prevents locomotor impairment in dystrophic mice. In conclusion, our study uncovers a PAX7-CB1 cross talk potentially exacerbating DMD and highlights the role of CB1 receptors as target for potential therapies.

Effect of chronic THC administration in the reproductive organs of male mice, spermatozoa and in vitro fertilization

The increased use of cannabis as a therapeutic drug in recent years has raised some concerns due to its potential effects on reproductive health. With regards to the male, the endocannabinoid system is involved in the spermatogenesis and in the sperm function. The chronic use of tetrahidrocannabinol (THC) has been associated with sperm anomalies, decreased sperm motility and structural changes in the testis. However, whether THC affects sperms ability to fertilize and to generate embryos remains unclear. The aim of this study was to evaluate this effect using a mice model of THC chronic treatment. For this purpose, a chronic treatment with THC was carried out. Mice were randomly allocated into two groups: an experimental group treated with a daily dose of 10 mg/kg-body weight THC for a period of 30 days and a control group treated with a vehicle. The THC-mice cortex showed a significant decrease of mRNA of Cnr1 compared to control-mice while, in the testis, the expression of Cnr1 was not affected. The weight of testis and epididymis and the histological analysis did not show any change between groups. On the other hand, no changes were observed in the sperm motility or the sperm concentration. The chronic use of THC did not generate any methylation change in the three CpG regions of Cnn1 analysed, neither in the brain nor in the embryos generated by in vitro fertilization (IVF). Finally, the embryo production by IVF was no different using spermatozoa from both THC and control mice. This work contradicts the belief that THC consumption has a negative effect on male reproductive processes.

A preliminary study of endocannabinoid system regulation in psychosis: Distinct alterations of CNR1 promoter DNA methylation in patients with schizophrenia

Compelling evidence supports the involvement of the endocannabinoid system (ECS) in psychosis vulnerability. We here evaluated the transcriptional regulation of ECS components in human peripheral blood mononuclear cells (PBMCs) obtained from subjects suffering from bipolar disorder, major depressive disorder and schizophrenia, focusing in particular on the effects of DNA methylation. We observed selective alterations of DNA methylation at the promoter of CNR1, the gene coding for the type-1 cannabinoid receptor, in schizophrenic patients (N=25) with no changes in any other disorder. We confirmed the regulation of CNR1 in a well-validated animal model of schizophrenia, induced by prenatal methylazoxymethanol (MAM) acetate exposure (N=7 per group) where we found, in the prefrontal cortex, a significant increase in CNR1 expression and a consistent reduction in DNA methylation at specific CpG sites of gene promoter. Overall, our findings suggest a selective dysregulation of ECS in psychosis, and highlight the evaluation of CNR1 DNA methylation levels in PBMCs as a potential biomarker for schizophrenia.

Spontaneous involution of pediatric low-grade gliomas: high expression of cannabinoid receptor 1 (CNR1) at the time of diagnosis may indicate involvement of the endocannabinoid system

BACKGROUND

Pediatric low-grade gliomas (P-LGG) consist of a mixed group of brain tumors that correspond to the majority of CNS tumors in children. Notably, they may exhibit spontaneous involution after subtotal surgical removal (STR). In this study, we investigated molecular indicators of spontaneous involution in P-LGG.

METHODS

We performed an integrated molecular analysis including high throughput gene expression (GE), microRNA (miRNA) expression data of primary, untreated tumors from patients with P-LGG who underwent STR at our institution, with at least 10 years follow-up.

RESULTS

We identified a set of protein-coding genes and miRNAs significantly differentially expressed in P-LGG that presented spontaneous involution (involution-I) or without progression (stable-S) after STR alone. The cannabinoid receptor 1 (CNR1 or CB1) gene (FC = 2.374; p value = 0.007) was at the top of the list and predicted to be regulated by hsa-miR-29b-3p (FC = -2.353, p value = 0.0001). CNR1 also showed a trend to be higher expressed in S/I by immunohistochemistry.

CONCLUSIONS

The P-LGG, which remained stable or that presented spontaneous involution after STR, showed significantly higher CNR1 expression at the time of diagnosis. We hypothesize that high expression levels of CNR1 provide tumor susceptibility to the antitumor effects of circulating endocannabinoids like anandamide, resulting in tumor involution. This corroborates with reports suggesting that CNR1 agonists and activators of the endocannabinoid system may represent therapeutic opportunities for children with LGG. We also suggest that CNR1 may be a prognostic marker for P-LGG. This is the first time spontaneous involution of P-LGG has been suggested to be induced by endocannabinoids.

Iron overload causes osteoporosis in thalassemia major patients through interaction with transient receptor potential vanilloid type 1 (TRPV1) channels

The pathogenesis of bone resorption in β-thalassemia major is multifactorial and our understanding of the underlying molecular and cellular mechanisms remains incomplete. Considering the emerging importance of the endocannabinoid/endovanilloid system in bone metabolism, it may be instructive to examine a potential role for this system in the development of osteoporosis in patients with β-thalassemia major and its relationship with iron overload and iron chelation therapy. This study demonstrates that, in thalassemic-derived osteoclasts, tartrate-resistant acid phosphatase expression inversely correlates with femoral and lumbar bone mineral density, and directly correlates with ferritin levels and liver iron concentration. The vanilloid agonist resiniferatoxin dramatically reduces cathepsin K levels and osteoclast numbers in vitro, without affecting tartrate-resistant acid phosphatase expression. The iron chelators deferoxamine, deferiprone and deferasirox decrease both tartrate-resistant acid phosphatase and cathepsin K expression, as well as osteoclast activity. Taken together, these data show that transient receptor potential vanilloid type 1 activation/desensitization influences tartrate-resistant acid phosphatase expression and activity, and this effect is dependent on iron, suggesting a pivotal role for iron overload in the dysregulation of bone metabolism in patients with thalassemia major. Our applied pharmacology provides evidence for the potential of iron chelators to abrogate these effects by reducing osteoclast activity. Whether iron chelation therapy is capable of restoring bone health in humans requires further study, but the potential to provide dual benefits for patients with β-thalassemia major -preventing iron-overload and alleviating associated osteoporotic changes - is exciting.

Type 1 cannabinoid receptor ligands display functional selectivity in a cell culture model of striatal medium spiny projection neurons

Modulation of type 1 cannabinoid receptor (CB1) activity has been touted as a potential means of treating addiction, anxiety, depression, and neurodegeneration. Different agonists of CB1 are known to evoke varied responses in vivo. Functional selectivity is the ligand-specific activation of certain signal transduction pathways at a receptor that can signal through multiple pathways. To understand cannabinoid-specific functional selectivity, different groups have examined the effect of individual cannabinoids on various signaling pathways in heterologous expression systems. In the current study, we compared the functional selectivity of six cannabinoids, including two endocannabinoids (2-arachidonyl glycerol (2-AG) and anandamide (AEA)), two synthetic cannabinoids (WIN55,212-2 and CP55,940), and two phytocannabinoids (cannabidiol (CBD) and Δ(9)-tetrahydrocannabinol (THC)) on arrestin2-, Gα(i/o)-, Gβγ-, Gα(s)-, and Gα(q)-mediated intracellular signaling in the mouse STHdh(Q7/Q7) cell culture model of striatal medium spiny projection neurons that endogenously express CB1. In this system, 2-AG, THC, and CP55,940 were more potent mediators of arrestin2 recruitment than other cannabinoids tested. 2-AG, AEA, and WIN55,212-2, enhanced Gα(i/o) and Gβγ signaling, with 2-AG and AEA treatment leading to increased total CB1 levels. 2-AG, AEA, THC, and WIN55,212-2 also activated Gα(q)-dependent pathways. CP55,940 and CBD both signaled through Gα(s). CP55,940, but not CBD, activated downstream Gα(s) pathways via CB1 targets. THC and CP55,940 promoted CB1 internalization and decreased CB1 protein levels over an 18-h period. These data demonstrate that individual cannabinoids display functional selectivity at CB1 leading to activation of distinct signaling pathways. To effectively match cannabinoids with therapeutic goals, these compounds must be screened for their signaling bias.

Cannabinoids in pain management: CB1, CB2 and non-classic receptor ligands

INTRODUCTION

Commercially available cannabinoids are subject to psychotomimetic and addiction (cannabinomimetic) adverse effects largely through activation of the cannabinoid 1 receptor (CB1r). The available commercial cannabinoids have a narrow therapeutic index. Recently developed peripherally restricted cannabinoids, regionally administered cannabinoids, bifunctional cannabinoid ligands and cannabinoid enzyme inhibitors, endocannabinoids, which do not interact with classic cannabinoid receptors (CB1r and CB2r), cannabinoid receptor antagonists and selective CB1r agonists hold promise as analgesics.

AREAS COVERED

This author provides a review of the current investigational cannabinoids currently in development for pain management. The author also provides their perspective on the future of the field.

EXPERT OPINION

Regional and peripherally restricted cannabinoids will reduce cannabinomimetic side effects. Spinal cannabinoids may increase the therapeutic index by limiting the dose necessary for response and minimize drugs exposure to supraspinal sites where cannabinomimetic side effects originate. Cannabinoid bifunctional ligands should be further explored. The combination of a CB2r agonist with a transient receptor potential vanilloid (TRPV-1) antagonist may improve the therapeutic index of the CB2r agonist. Enzyme inhibitors plus TRPV-1 blockers should be further explored. The development of analgesic tolerance with enzyme inhibitors and the pronociceptive effects of prostamides limit the benefits to cannabinoid hydrolyzing enzyme inhibitors. Most clinically productive development of cannabinoids over the next 5 years will be in the area of selective CB2r agonists. These agents will be tested in various inflammatory, osteoarthritis and neuropathic pains.

Cannabinoids increase type 1 cannabinoid receptor expression in a cell culture model of striatal neurons: implications for Huntington's disease

The type 1 cannabinoid receptor (CB1) is a G protein-coupled receptor that is expressed at high levels in the striatum. Activation of CB1 increases expression of neuronal trophic factors and inhibits neurotransmitter release from GABA-ergic striatal neurons. CB1 mRNA levels can be elevated by treatment with cannabinoids in non-neuronal cells. We wanted to determine whether cannabinoid treatment could induce CB1 expression in a cell culture model of striatal neurons and, if possible, determine the molecular mechanism by which this occurred. We found that treatment of STHdh(7/7) cells with the cannabinoids ACEA, mAEA, and AEA produced a CB1receptor-dependent increase in CB1 promoter activity, mRNA, and protein expression. This response was Akt- and NF-κB-dependent. Because decreased CB1 expression is thought to contribute to the pathogenesis of Huntington's disease (HD), we wanted to determine whether cannabinoids could increase CB1 expression in STHdh(7/111) and (111/111) cells expressing the mutant huntingtin protein. We observed that cannabinoid treatment increased CB1 mRNA levels approximately 10-fold in STHdh(7/111) and (111/111) cells, compared to vehicle treatment. Importantly, cannabinoid treatment improved ATP production, increased the expression of the trophic factor BDNF-2, and the mitochondrial regulator PGC1α, and reduced spontaneous GABA release, in HD cells. Therefore, cannabinoid-mediated increases in CB1 levels could reduce the severity of some molecular pathologies observed in HD.