The endocannabinoid system modulates stress, emotionality, and inflammation

Different stressors uniquely affect the expression of endocannabinoid-metabolizing enzymes in the central ring ganglia of Lymnaea stagnalis

The endocannabinoid system (ECS) plays an important role in neuroprotection, neuroplasticity, energy balance, modulation of stress, and inflammatory responses, acting as a critical link between the brain and the body's peripheral regions, while also offering promising potential for novel therapeutic strategies. Unfortunately, in humans, pharmacological inhibitors of different ECS enzymes have led to mixed results in both preclinical and clinical studies. As the ECS has been highly conserved throughout the eukaryotic lineage, the use of invertebrate model organisms like the pond snail Lymnaea stagnalis may provide a flexible tool to unravel unexplored functions of the ECS at the cellular, synaptic, and behavioral levels. In this study, starting from the available genome and transcriptome of L. stagnalis, we first identified putative transcripts of all ECS enzymes containing an open reading frame. Each predicted protein possessed a high degree of sequence conservation to known orthologues of other invertebrate and vertebrate organisms. Sequences were confirmed by qualitative PCR and sequencing. Then, we investigated the transcriptional effects induced by different stress conditions (i.e., bacterial LPS injection, predator scent, food deprivation, and acute heat shock) on the expression levels of the enzymes of the ECS in Lymnaea's central ring ganglia. Our results suggest that in Lymnaea as in rodents, the ECS is involved in mediating inflammatory and anxiety-like responses, promoting energy balance, and responding to acute stressors. To our knowledge, this study offers the most comprehensive analysis so far of the ECS in an invertebrate model organism.

Effects of cannabidiol, with and without ∆9-tetrahydrocannabinol, on anxiety-like behavior following alcohol withdrawal in mice

Introduction

Alcohol use disorder (AUD) is commonly associated with anxiety disorders and enhanced stress-sensitivity; symptoms that can worsen during withdrawal to perpetuate continued alcohol use. Alcohol increases neuroimmune activity in the brain. Our recent evidence indicates that alcohol directly modulates neuroimmune function in the central amygdala (CeA), a key brain region regulating anxiety and alcohol intake, to alter neurotransmitter signaling. We hypothesized that cannabinoids, such as cannabidiol (CBD) and ∆9-tetrahydrocannabinol (THC), which are thought to reduce neuroinflammation and anxiety, may have potential utility to alleviate alcohol withdrawal-induced stress-sensitivity and anxiety-like behaviors via modulation of CeA neuroimmune function.

Methods

We tested the effects of CBD and CBD:THC (3:1 ratio) on anxiety-like behaviors and neuroimmune function in the CeA of mice undergoing acute (4-h) and short-term (24-h) withdrawal from chronic intermittent alcohol vapor exposure (CIE). We further examined the impact of CBD and CBD:THC on alcohol withdrawal behaviors in the presence of an additional stressor.

Results

We found that CBD and 3:1 CBD:THC increased anxiety-like behaviors at 4-h withdrawal. At 24-h withdrawal, CBD alone reduced anxiety-like behaviors while CBD:THC had mixed effects, showing increased center time indicating reduced anxiety-like behaviors, but increased immobility time that may indicate increased anxiety-like behaviors. These mixed effects may be due to altered metabolism of CBD and THC during alcohol withdrawal. Immunohistochemical analysis showed decreased S100β and Iba1 cell counts in the CeA at 4-h withdrawal, but not at 24-h withdrawal, with CBD and CBD:THC reversing alcohol withdrawal effects..

Discussion

These results suggest that the use of cannabinoids during alcohol withdrawal may lead to exacerbated anxiety depending on timing of use, which may be related to neuroimmune cell function in the CeA.

Longitudinal course of endocannabinoids and N-acylethanolamines in hair of mothers and their children in the first year postpartum: investigating the relevance of maternal childhood maltreatment experiences

BACKGROUND

Childhood maltreatment (CM) exerts long-lasting psychological and biological alterations in affected individuals and might also affect the endocannabinoid (eCB) system which modulates inflammation and the endocrine stress response. Here, we investigated the eCB system of women with and without CM and their infants using hair samples representing eCB levels accumulated during the last trimester of pregnancy and 10-12 months postpartum.

METHODS

CM exposure was assessed with the Childhood Trauma Questionnaire. At both timepoints, 3 cm hair strands were collected from mothers and children (N = 170 resp. 150) to measure anandamide (AEA), 2/1-arachidonoylglycerol (2-AG/1-AG), stearoylethanolamide (SEA), oleoylethanolamide (OEA), and palmitoylethanolamide (PEA).

RESULTS

Maternal hair levels of 2-AG/1-AG increased and SEA levels decreased from late pregnancy to one year postpartum. Maternal CM was associated with lower SEA levels in late pregnancy, but not one year later. In the children's hair, levels of 2-AG/1-AG increased while levels of SEA, OEA, and PEA decreased from late pregnancy to one year later. Maternal CM was not consistently associated with the eCB levels measured in children's hair.

CONCLUSIONS

We provide first evidence for longitudinal change in the eCB system of mothers and infants from pregnancy to one year later. While maternal CM influenced the maternal eCB system, we found no consistent intergenerational effects on early regulation of the eCB system in children. Longitudinal research on the importance of the eCB system for the course and immunoregulation of pregnancy as well as for the children's development.

The Endogenous Cannabinoid and the Nitricoxidergic Systems in the Modulation of Stress Responses

The effects on stress-induced analgesia (SIA) from endogenous cannabinoid system (ECS) and nitric oxide (NO) interaction after 1 h of restraint stress were evaluated in male Wistar rats. The animals were subjected to 1 h of restraint and then injected with different combinations of cannabinoid receptor type 1 agonist anandamide (AEA) or antagonist AM251 along with an NO donor, NO precursor, or inhibitor of NO synthase. Nociception was evaluated using paw pressure (PP) or hot plate (HP) tests. AEA was administered immediately after the end of restraint-SIA (r-SIA). Administration of NO precursor reversed the pronociceptive effect of the CB1 agonist on r-SIA. Both the CB1 antagonist and the NOS inhibitor neutralized the pro-analgesic effect of L-arginine (L-arg). Administration of an NO donor, instead, increased r-SIA. Our experiments confirmed that the endogenous cannabinoid and the NO-ergic systems interact in the modulation of r-SIA. This interaction probably implies NO as a second messenger of the ECS.

Role of the endocannabinoid system in the pathophysiology of endometriosis and therapeutic implications

Endometriosis patients experience debilitating chronic pain, and the first-line treatment is ineffective at managing symptoms. Although surgical removal of the lesions provides temporary relief, more than 50% of the patients experience disease recurrence. Despite being a leading cause of hysterectomy, endometriosis lacks satisfactory treatments and a cure. Another challenge is the poor understanding of disease pathophysiology which adds to the delays in diagnosis and overall compromised quality of life. Endometriosis patients are in dire need of an effective therapeutic strategy that is both economical and effective in managing symptoms, while fertility is unaffected. Endocannabinoids and phytocannabinoids possess anti-inflammatory, anti-nociceptive, and anti-proliferative properties that may prove beneficial for endometriosis management, given that inflammation, vascularization, and pain are hallmark features of endometriosis. Endocannabinoids are a complex network of molecules that play a central role in physiological processes including homeostasis and tissue repair, but endocannabinoids have also been associated in the pathophysiology of several chronic inflammatory diseases including endometriosis and cancers. The lack of satisfactory treatment options combined with the recent legalization of recreational cannabinoids in some parts of the world has led to a rise in self-management strategies including the use of cannabinoids for endometriosis-related pain and other symptoms. In this review, we provide a comprehensive overview of endocannabinoids with a focus on their potential roles in the pathophysiology of endometriosis. We further provide evidence-driven perspectives on the current state of knowledge on endometriosis-associated pain, inflammation, and therapeutic avenues exploiting the endocannabinoid system for its management.

Endocannabinoid system in the neuroendocrine response to LPS-induced immune challenge

The endocannabinoid system plays a key role in the intersection of the nervous, endocrine, and immune system, regulating not only their functions but also how they interplay with each other. Endogenous ligands, named endocannabinoids, are produced “on demand” to finely regulate the synthesis and secretion of hormones and neurotransmitters, as well as to regulate the production of cytokines and other proinflammatory mediators.

It is well known that immune challenges, such as exposure to lipopolysaccharide (LPS), the main component of the Gram-negative bacteria cell wall, disrupts not only the hypothalamic-pituitary-adrenal axis but also affects other endocrine systems such as the hypothalamic-pituitary-gonadal axis and the release of oxytocin from the neurohypophysis. Here we explore which actors and molecular mechanisms are involved in these processes.

Subregional Differences in Alcohol Modulation of Central Amygdala Neurocircuitry

Alcohol use disorder is a highly significant medical condition characterized by an impaired ability to stop or control alcohol use, compulsive alcohol seeking behavior, and withdrawal symptoms in the absence of alcohol. Understanding how alcohol modulates neurocircuitry critical for long term and binge-like alcohol use, such as the central amygdala (CeA), may lead to the development of novel therapeutic strategies to treat alcohol use disorder. In clinical studies, reduction in the volume of the amygdala has been linked with susceptibility to relapse to alcohol use. Preclinical studies have shown the involvement of the CeA in the effects of alcohol use, with lesions of the amygdala showing a reduction in alcohol drinking, and manipulations of cells in the CeA altering alcohol drinking. A great deal of work has shown that acute alcohol, as well as chronic alcohol exposure via intake or dependence models, alters glutamatergic and GABAergic transmission in the CeA. The CeA, however, contains heterogeneous cell populations and distinct subregional differences in neurocircuit architecture which may influence the mechanism by which alcohol modulates CeA function overall. The current review aimed to parse out the differences in alcohol effects on the medial and lateral subregions of the CeA, and what role neuroinflammatory cells and markers, the endocannabinoid system, and the most commonly studied neuropeptide systems play in mediating these effects. A better understanding of alcohol effects on CeA subregional cell type and neurocircuit function may lead to development of more selective pharmacological interventions for alcohol use disorder.

Effects of waterpipe tobacco smoke and ceftriaxone treatment on the expression of endocannabinoid receptors in mesocorticolimbic brain regions

Chronic tobacco exposure can alter the endocannabinoid (eCB) system, consequently leading to an anxiety state. In this study, we investigated the effects of waterpipe tobacco smoke (WTS) on cannabinoid receptor 1 and 2 (CBR1 and CBR2) gene and protein expression in mesocorticolimbic brain regions. Using elevated plus maze (EPM) and open field (OF) tests, the effects of WTS exposure on withdrawal-induced anxiety-like behavior were examined. The effect of ceftriaxone (CEF), a β-lactam known to upregulate glutamate transporter 1 (GLT-1), on anxiety and the expression of cannabinoid receptors was also determined. Male Sprague-Dawley rats were randomly assigned to four groups: 1) the Control group was exposed only to standard room air; 2) the WTS group was exposed to tobacco smoke and treated with saline vehicle; 3) the WTS-CEF group was exposed to WTS and treated with ceftriaxone; and 4) the CEF group was exposed only to standard room air and treated with ceftriaxone. Rats were exposed to WTS (or room air) for two hours per day, five days per week for a period of four weeks. Behavioral tests (EPM and OF) were conducted weekly during acute withdrawal, 24 h following WTS exposure. Rats were given either saline or ceftriaxone (200 mg/kg i.p.) for five days during Week 4, 30 min prior to WTS exposure. Withdrawal-induced anxiety was induced by WTS exposure but was reduced by ceftriaxone treatment. WTS exposure decreased CBR1 mRNA and protein expression in the NAc and VTA, but not PFC, and ceftriaxone treatment attenuated these effects. WTS exposure did not change CBR2 mRNA expression in the NAc, VTA, or PFC. These findings demonstrate that WTS exposure dysregulated the endocannabinoid system and increased anxiety-like behavior, and these effects were reversed by ceftriaxone treatment, which suggest the involvement of glutamate transporter 1 in these effects.

Acute stress and alcohol exposure during adolescence result in an anxious phenotype in adulthood: Role of altered glutamate/endocannabinoid transmission mechanisms

BACKGROUND

Stressful episodes and high alcohol consumption during adolescence are considered major risk factors for the development of psychiatric disorders in adulthood. Identification of mechanisms underlying these early events, which enhanced vulnerability to mental illness, is essential for both their prevention and treatment.

METHODS

Male Wistar rats were used to investigate the long-term effects of early restraint stress and intermittent alcohol exposure (intragastric administration of 3 g/kg ethanol; 4 days/week for 4 weeks during adolescence) on anxiety-like behavior and the expression of signaling systems associated with emotional behaviors [e.g., corticosterone, fatty acid-derived molecules and endocannabinoid enzymes, glutamate receptor subunits, corticotropin releasing hormone receptors (CRHR1 and CRHR2) and neuropeptide Y receptors (NPY1R and NPYR2)] in the blood and amygdala.

RESULTS

Overall, both stress and alcohol exposure during adolescence induced anxiogenic-like behaviors, increased plasma levels of corticosterone and increases in the amygdalar expression of the cannabinoid CB₂ receptor and certain subunits of glutamate receptors (i.e., mGluR1, mGluR5 and NMDAR1) in young adult rats. In addition, there were specific main effects of alcohol exposure on the expression of the cannabinoid CB₁ receptor, monoacylglycerol lipase (MAGL) and NPY2R in the amygdala, and significant increases were observed in rats exposed to alcohol. Interestingly, there were significant interaction effects between restraint stress and alcohol exposure on the expression of plasma 2-arachidonoyl glycerol (2-AG), and both CRHR1,2 and NPY1R in the amygdala. Thus, the restraint stress was associated with increased 2-AG levels, which was not observed in rats exposed to alcohol. The alcohol exposure was associated with an increased expression of CRHR1,2 but the restraint stress prevented these increases (stress alcohol rats). In contrast, NPY1R was only increased in rats exposed to stress and alcohol. Finally, we did not observe any potentiation of the behavioral and molecular effects by the combination of stress and alcohol, which is concordant with an overall ceiling effect on some of the variables.

CONCLUSION

Separate and combined early stress and alcohol induced a common anxious phenotype with increased corticosterone in adulthood. However, there were differences in the amygdalar expression of signaling systems involved in maladaptive changes in emotional behavior. Therefore, our results suggest the existence of partially different mechanisms for stress and alcohol exposures.

Endocannabinoid system contributions to sex-specific adolescent neurodevelopment

With an increasing number of countries and states adopting legislation permitting the use of cannabis for medical purposes, there is a growing interest among health and research professionals into the system through which cannabinoids principally act, the endocannabinoid system (ECS). Much of the seminal research into the ECS dates back only 30 years and, although there has been tremendous development within the field during this time, many questions remain. More recently, investigations have emerged examining the contributions of the ECS to normative development and the effect of altering this system during important critical periods. One such period is adolescence, a unique period during which brain and behaviours are maturing and reorganizing in preparation for adulthood, including shifts in endocannabinoid biology. The purpose of this review is to discuss findings to date regarding the maturation of the ECS during adolescence and the consequences of manipulations of the ECS during this period to normative neurodevelopmental processes, as well as highlight sex differences in ECS function, important technical considerations, and future directions. Because most of what we know is derived from preclinical studies on rodents, we provide relevant background of this model and some commentary on the translational relevance of the research in this area.

The Management of Cancer Symptoms and Treatment-Induced Side Effects With Cannabis or Cannabinoids

Cannabis and cannabinoids are increasingly being accessed and used by patients with advanced cancer for various symptoms and general quality of life. Specific symptoms of pain, nausea and vomiting, loss of appetite and cachexia, anxiety, sleep disturbance, and medical trauma are among those that have prompted patients with cancer to use cannabis. This conference report from the National Cancer Institute's "Cannabis, Cannabinoid and Cancer Research Symposium" on the topic of "Cancer Symptom/Treatment Side Effect Management" is an expert perspective of cannabis intervention for cancer and cancer treatment-related symptoms. The purpose of the symposium was to identify research gaps, describe the need for high-quality randomized prospective studies of medical cannabis for palliative care in patients with cancer, and evaluate the impact of medical cannabis on cancer survivors' quality of life. Further, education of clinicians and affiliated health-care providers in guiding cancer patients in using cannabis for cancer care would benefit patients. Together, these steps will further aid in refining the use of cannabis and cannabinoids for symptom palliation and improve safety and efficacy for patients.

Loneliness: An Immunometabolic Syndrome

Loneliness has been defined as an agonizing encounter, experienced when the need for human intimacy is not met adequately, or when a person’s social network does not match their preference, either in number or attributes. This definition helps us realize that the cause of loneliness is not merely being alone, but rather not being in the company we desire. With loneliness being introduced as a measurable, distinct psychological experience, it has been found to be associated with poor health behaviors, heightened stress response, and inadequate physiological repairing activity. With these three major pathways of pathogenesis, loneliness can do much harm; as it impacts both immune and metabolic regulation, altering the levels of inflammatory cytokines, growth factors, acute-phase reactants, chemokines, immunoglobulins, antibody response against viruses and vaccines, and immune cell activity; and affecting stress circuitry, glycemic control, lipid metabolism, body composition, metabolic syndrome, cardiovascular function, cognitive function and mental health, respectively. Taken together, there are too many immunologic and metabolic manifestations associated with the construct of loneliness, and with previous literature showcasing loneliness as a distinct psychological experience and a health determinant, we propose that loneliness, in and of itself, is not just a psychosocial phenomenon. It is also an all-encompassing complex of systemic alterations that occur with it, expanding it into a syndrome of events, linked through a shared network of immunometabolic pathology. This review aims to portray a detailed picture of loneliness as an “immunometabolic syndrome”, with its multifaceted pathology.

A Physiologically Based Pharmacokinetic and Drug-Drug Interaction Model for the CB2 Agonist Lenabasum

BACKGROUND AND OBJECTIVES

Lenabasum is a synthetic agonist of the cannabinoid receptor type 2 (CB2) with anti-inflammatory and antifibrotic properties. Utilizing Simcyp, we developed a physiologically based pharmacokinetic (PBPK) model based on physicochemical properties, cell culture data, and cytochrome P450 (CYP) phenotyping, inhibition, and induction data.

METHODS

Clinical data from healthy volunteers treated with 20 mg of lenabasum in a single ascending dose (SAD) study were used for model development. The model was verified using lenabasum SAD (10 and 40 mg) data as well as multiple dose (20 mg three times per day) data. Lenabasum is a CYP substrate, and the model predicted lenabasum clearance of 51% by CYP2C9, 37% by CYP2C8, and 12% by CYP3A4. Lenabasum is also an inhibitor of these isozymes.

RESULTS

The model accurately described the area under the plasma concentration-time curve (AUC) and maximum plasma concentration (C_max) for lenabasum within 1.19-fold and 1.25-fold accuracy, respectively, of the observed clinical values. The simulations of CYP inducers predicted that the strongest interaction would occur with rifampin, with the AUC decreasing to 0.36 of the control value, whereas the simulations of CYP inhibitors predicted that the greatest effect would occur with fluconazole, with a 1.43-fold increase in AUC.

CONCLUSIONS

Our model is a useful tool for predicting the pharmacokinetics of lenabasum and adjustments to its dosing in possible drug-drug interaction scenarios.

Traumatic Stress, Chronic Ethanol Exposure, or the Combination, Alter Cannabinoid System Components in Reward and Limbic Regions of the Mouse Brain

The cannabinoid system is independently affected by stress and chronic ethanol exposure. However, the extent to which co-occurrence of traumatic stress and chronic ethanol exposure modulates the cannabinoid system remains unclear. We examined levels of cannabinoid system components, anandamide, 2-arachidonoylglycerol, fatty acid amide hydrolase, and monoacylglycerol lipase after mouse single-prolonged stress (mSPS) or non-mSPS (Control) exposure, with chronic intermittent ethanol (CIE) vapor or without CIE vapor (Air) across several brain regions using ultra-high-performance liquid chromatography tandem mass spectrometry or immunoblotting. Compared to mSPS-Air mice, anandamide and 2-arachidonoylglycerol levels in the anterior striatum were increased in mSPS-CIE mice. In the dorsal hippocampus, anandamide content was increased in Control-CIE mice compared to Control-Air, mSPS-Air, or mSPS-CIE mice. Finally, amygdalar anandamide content was increased in Control-CIE mice compared to Control-Air, or mSPS-CIE mice, but the anandamide content was decreased in mSPS-CIE compared to mSPS-Air mice. Based on these data we conclude that the effects of combined traumatic stress and chronic ethanol exposure on the cannabinoid system in reward pathway regions are driven by CIE exposure and that traumatic stress affects the cannabinoid components in limbic regions, warranting future investigation of neurotherapeutic treatment to attenuate these effects.

Distribution of the Cannabinoid Receptor Type 1 in the Brain of the Genetically Audiogenic Seizure-Prone Hamster GASH/Sal

The endocannabinoid system modulates epileptic seizures by regulating neuronal excitability. It has become clear that agonist activation of central type I cannabinoid receptors (CB1R) reduces epileptogenesis in pre-clinical animal models of epilepsy. The audiogenic seizure-prone hamster GASH/Sal is a reliable experimental model of generalized tonic-clonic seizures in response to intense sound stimulation. However, no studies hitherto had investigated CB1R in the GASH/Sal. Although the distribution of CB1R has been extensively studied in mammalian brains, their distribution in the Syrian golden hamster brain also remains unknown. The objective of this research is to determine by immunohistochemistry the differential distribution of CB1R in the brains of GASH/Sal animals under seizure-free conditions, by comparing the results with wild-type Syrian hamsters as controls. CB1R in the GASH/Sal showed a wide distribution in many nuclei of the central nervous system. These patterns of CB1R-immunolabeling are practically identical between the GASH/Sal model and control animals, varying in the intensity of immunostaining in certain regions, being slightly weaker in the GASH/Sal than in the control, mainly in brain regions associated with epileptic networks. The RT-qPCR analysis confirms these results. In summary, our study provides an anatomical basis for further investigating CB1R in acute and kindling audiogenic seizure protocols in the GASH/Sal model as well as exploring CB1R activation via exogenously administered cannabinoid compounds.

Modern approaches to the development of synthetic cannabinoid receptor probes

The endocannabinoid system, which spans the central and peripheral nervous systems and regulates many biologic processes, is an important target for probe discovery and medications development. Whereas the earliest endocannabinoid receptor probes were derivatives of the non-selective phytocannabinoids isolated from Cannabis species, modern drug discovery techniques have expanded the definitions of what constitutes a CB1R or CB2R cannabinoid receptor ligand. This review highlights recent advances in synthetic cannabinoid receptor chemistry and pharmacology. We provide examples of new CB1R- and CB2R-selective probes, and discuss rational approaches to the design of peripherally-restricted agents. We also describe structural classes of positive- and negative allosteric modulators (PAMs and NAMs) of CB1R and CB2R. Finally, we introduce new opportunities for cannabinoid receptor probe development that have emerged in recent years, including biased agonists that may lead to medications lacking adverse effects.

Targeting the Endocannabinoid System in Borderline Personality Disorder: Corticolimbic and Hypothalamic Perspectives

Borderline Personality Disorder (BPD) is a chronic debilitating psychiatric disorder characterized mainly by emotional instability, chaotic interpersonal relationships, cognitive disturbance (e.g., dissociation and suicidal thoughts) and maladaptive behaviors. BPD has a high rate of comorbidity with other mental disorders and a high burden on society. In this review, we focused on two compromised brain regions in BPD - the hypothalamus and the corticolimbic system, emphasizing the involvement and potential contribution of the endocannabinoid system (ECS) to improvement in symptoms and coping. The hypothalamus-regulated endocrine axes (hypothalamic pituitary - gonadal, thyroid & adrenal) have been found to be dysregulated in BPD. There is also substantial evidence for limbic system structural and functional changes in BPD, especially in the amygdala and hippocampus, including cortical regions within the corticolimbic system. Extensive expression of CB1 and CB2 receptors of the ECS has been found in limbic regions and the hypothalamus. This opens new windows of opportunity for treatment with cannabinoids such as cannabidiol (CBD) as no other pharmacological treatment has shown long-lasting improvement in the BPD population to date. This review aims to show the potential role of the ECS in BPD patients through their most affected brain regions, the hypothalamus and the corticolimbic system. The literature reviewed does not allow for general indications of treatment with CBD in BPD. However, there is enough knowledge to indicate a treatment ratio of a high level of CBD to a low level of THC. A randomized controlled trial investigating the efficacy of cannabinoid based treatments in BPD is warranted.

Differential effect of interferon-alpha treatment on AEA and 2-AG levels

The endocannabinoid (eCB) system is one of the key players in immunoregulation, and reduced activity of the eCB system has been linked with depressive-like behaviours in animal studies and depression in clinical samples. There is a well-established link between immune activation and depression, such as following the administration of the pro-inflammatory cytokine, interferon-α (IFN-α), used to treat hepatitis C viral (HCV) infection. However, the role of peripheral endocannabinoids (eCBs), anandamide (AEA) and 2-arachidonoylglycerol (2-AG), following immunotherapy with IFN-α and in IFN-α -induced depression, have not been examined yet. In this study, we investigated whether circulating AEA and 2-AG were modified by treatment with IFN-α and whether they were involved in the development of IFN-α-induced depression. We also explored whether circulating eCBs were associated with peripheral cytokines during and after IFN-α treatment. We measured serum concentrations of AEA and 2-AG using High Performance Liquid Chromatography with Tandem Mass Spectrometry, and serum concentrations of cytokines using Meso Scale Discovery electrochemiluminescence V-PLEX assay, in 70 patients with HCV infection and 41 healthy subjects. We assessed HCV patients at baseline, IFN-α-treatment weeks (TW) 4 and 24, end of treatment (END) and at six months follow-up (FU). We assessed depression using M.I.N.I. International Neuropsychiatric Interview. We found a different pattern of change in peripheral AEA and 2-AG during and after IFN-α treatment. Whilst 2-AG increased earlier in immunotherapy (TW4), remained elevated throughout treatment, and reduced at six months follow-up (FU), AEA increased later in treatment (TW24) and remained elevated six months post-treatment. We also found that baseline levels of AEA were lower in HCV patients compared with healthy controls, whereas there were no differences in 2-AG levels. Interestingly, AEA, but not 2-AG, was significantly, negatively correlated with interleukin (IL)-2 and IL-17a at six months follow-up. We did not find any difference in both eCBs between patients with and without IFN-α-induced depression, at any time point. Our findings suggest that AEA and 2-AG are involved in different stages of immunoregulation following IFN-α treatment, where AEA might be involved in chronic inflammation. Lack of association between peripheral eCBs and IFN-α-induced depression suggests that different biological mechanisms may underpin inflammation-induced depression compared with classic "psychiatric" depression, or that any changes in the eCB system in depression may not be captured by peripheral AEA and 2-AG.

Chronic Intermittent Ethanol Exposure Increases Ethanol Consumption Following Traumatic Stress Exposure in Mice

Individuals with post-traumatic stress disorder (PTSD) often use alcohol to cope with their distress. This aberrant use of alcohol often develops into alcohol use disorder (AUD) leading to high rates of PTSD-AUD co-occurrence. Individuals with comorbid PTSD-AUD have more intense alcohol cravings and increased relapse rates during withdrawal than those with AUD alone. Also, individuals with PTSD or AUD alone often show similar psychological behaviors, such as impulsivity and anhedonia. Extensive clinical studies on the behavioral effects of PTSD-AUD comorbidity, namely alcohol use, have been performed. However, these effects have not been well studied or mechanistically explored in animal models. Therefore, the present study evaluated the effects of traumatic stress comorbid with alcohol exposures on ethanol intake, impulsivity, and anhedonia in mice. Adult male C57Bl/6 mice were first exposed to either mouse single-prolonged stress (mSPS), an animal model that has been validated for characteristics akin to PTSD symptoms, or control conditions. Baseline two-bottle choice ethanol consumption and preference tests were conducted after a 7-day isolation period, as part of the mSPS exposure. Next, mice were exposed to air or chronic intermittent ethanol (CIE), a vapor-induced ethanol dependence and withdrawal model, for 4 weeks. Two-bottle choice ethanol drinking was used to measure dependence-induced ethanol consumption and preference during periods intervening CIE cycles. The novelty suppressed feeding (NSF) test was used to evaluate impulsivity and anhedonia behaviors 48 h after mSPS and/or repeated CIE exposure. Results showed that, compared to control conditions, mSPS did not affect baseline ethanol consumption and preference. However, mSPS-CIE mice increased Post-CIE ethanol consumption compared to Control-Air mice. Mice exposed to mSPS had a shorter latency to feed during the NSF, whereas CIE-exposed mice consumed less palatable food reward in their home cage after the NSF. These results demonstrate that mice exposed to both mSPS and CIE are more vulnerable to ethanol withdrawal effects, and those exposed to mSPS have increased impulsivity, while CIE exposure increases anhedonia. Future studies to examine the relationship between behavioral outcomes and the molecular mechanisms in the brain after PTSD-AUD are warranted.

Stress-induced blood brain barrier disruption: Molecular mechanisms and signaling pathways

Stress is a nonspecific response to a threat or noxious stimuli with resultant damaging consequences. Stress is believed to be an underlying process that can trigger central nervous system disorders such as depression, anxiety, and post-traumatic stress disorder. Though the pathophysiological basis is not completely understood, data have consistently shown a pivotal role of inflammatory mediators and hypothalamo-pituitary-adrenal (HPA) axis activation in stress induced disorders. Indeed emerging experimental evidences indicate a concurrent activation of inflammatory signaling pathways and not only the HPA axis, but also, peripheral and central renin-angiotensin system (RAS). Furthermore, recent experimental data indicate that the HPA and RAS are coupled to the signaling of a range of central neuro-transmitter, -mediator and -peptide molecules that are also regulated, at least in part, by inflammatory signaling cascades and vice versa. More recently, experimental evidences suggest a critical role of stress in disruption of the blood brain barrier (BBB), a neurovascular unit that regulates the movement of substances and blood-borne immune cells into the brain parenchyma, and prevents peripheral injury to the brain substance. However, the mechanisms underlying stress-induced BBB disruption are not exactly known. In this review, we summarize studies conducted on the effects of stress on the BBB and integrate recent data that suggest possible molecular mechanisms and signaling pathways underlying stress-induced BBB disruption. Key molecular targets and pharmacological candidates for treatment of stress and related illnesses are also summarized.

Functional Characterization of Knock-In Mice Expressing a 12/15-Lipoxygenating Alox5 Mutant Instead of the 5-Lipoxygenating Wild-Type Enzyme

Aims: Most mammalian genomes involve several genes encoding for functionally distinct arachidonate lipoxygenase (ALOX isoforms). Proinflammatory leukotrienes are formed via the ALOX5 pathway, but 12/15-lipoxygenating ALOX isoforms have been implicated in the biosynthesis of pro-resolving mediators. In vitro mutagenesis of the triad determinants abolished the leukotriene synthesizing activity of ALOX5, but the biological consequences of these alterations have not been studied. To fill this gap, we created Alox5 knock-in mice, which express the 12/15-lipoxygenating Phe359Trp + Ala424Ile + Asn425Met Alox5 triple mutant and characterized its phenotypic alterations. Results: The mouse Alox5 triple mutant functions as arachidonic acid 15-lipoxygenating enzyme, which also forms 12S-hydroxy and 8S-hydroxy arachidonic acid. In contrast to the wild-type enzyme, the triple mutant effectively oxygenates linoleic acid to 13S-hydroxy linoleic acid (13S-HODE), which functions as activating ligand of the type-2 nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ). Knock-in mice expressing the mutant enzyme are viable, fertile, and develop normally. The mice cannot synthesize proinflammatory leukotrienes but show significantly attenuated plasma levels of lipolytic endocannabinoids. When aging, the animals gained significantly more body weight, which may be related to the fivefold higher levels of 13-HODE in the adipose tissue. Innovation: These data indicate for the first time that in vivo mutagenesis of the triad determinants of mouse Alox5 abolished the biosynthetic capacity of the enzyme for proinflammatory leukotrienes and altered the catalytic properties of the protein favoring the formation of 13-HODE. Conclusion:In vivo triple mutation of the mouse Alox5 gene impacts the body weight homeostasis of aging mice via augmented formation of the activating PPARγ ligand 13-HODE.

Endocannabinoid modulation of inflammatory hyperalgesia in the IFN-α mouse model of depression

Depression is a well-recognised effect of long-term treatment with interferon-alpha (IFN-α), a widely used treatment for chronic viral hepatitis and malignancy. In addition to the emotional disturbances, high incidences of painful symptoms such as headache and joint pain have also been reported following IFN-α treatment. The endocannabinoid system plays an important role in emotional and nociceptive processing, however it is unknown whether repeated IFN-α administration induces alterations in this system. The present study investigated nociceptive responding in the IFN-α-induced mouse model of depression and associated changes in the endocannabinoid system. Furthermore, the effects of modulating peripheral endocannabinoid tone on inflammatory pain-related behaviour in the IFN-α model was examined. Repeated IFN-α administration (8000 IU/g/day) to male C57/Bl6 mice increased immobility in the forced swim test and reduced sucrose preference, without altering body weight gain or locomotor activity, confirming development of the depressive-like phenotype. There was no effect of repeated IFN-α administration on latency to respond in the hot plate test on day 4 or 7 of treatment, however, formalin-evoked nociceptive behaviour was significantly increased in IFN-α treated mice following 8 days of IFN-α administration. 2-Arachidonoyl glycerol (2-AG) levels in the periaqueductal grey (PAG) and rostroventromedial medulla (RVM), and anandamide (AEA) levels in the RVM, were significantly increased in IFN-α-, but not saline-, treated mice following formalin administration. There was no change in endocannabinoid levels in the prefrontal cortex, spinal cord or paw tissue between saline- or IFNα-treated mice in the presence or absence of formalin. Furthermore, repeated IFN-α and/or formalin administration did not alter mRNA expression of genes encoding the endocannabinoid catabolic enzymes (fatty acid amide hydrolase or monoacylglycerol lipase) or endocannabinoid receptor targets (CB_1, CB₂ or PPARs) in the brain, spinal cord or paw tissue. Intra plantar administration of PF3845 (1 μg/10 μl) or MJN110 (1 μg/10 μl), inhibitors of AEA and 2-AG catabolism respectively, attenuated formalin-evoked hyperalgesia in IFN-α, but not saline-, treated mice. In summary, increasing peripheral endocannabinoid tone attenuates inflammatory hyperalgesia induced following repeated IFN-α administration. These data provide support for the endocannabinoid system in mediating and modulating heightened pain responding associated with IFNα-induced depression.

Cannabis, alcohol and cigarette use during the acute post-concussion period

Objective: To document the prevalence of acute post-concussion cannabis, alcohol and cigarette use and their association with clinical recovery and symptom burden.Methods: A prospective cohort study was conducted. Concussions were physician-diagnosed and presented to the emergency department and concussion clinic within 7 days post-injury. Participants were assessed weekly and followed for a minimum 4 weeks. A survival analysis (using physician-determined recovery to both cognitive and physical activities) in addition to a weekly symptom score analysis was conducted.Results: A total of 307 acute concussions with a mean age of 33.7 years (SD, 13.0) were included. Acute post-concussion cannabis, alcohol and cigarette use were identified in 43 (14.0%), 125 (40.7%) and 61 (19.9%) individuals. Acute cannabis, alcohol and cigarette use were not associated with recovery to cognitive (p > .05) or physical activity (p > .05). Acute cigarette use was associated with a higher unadjusted symptom severity score at week1 (p = .003). Acute cannabis use was associated with lower symptom severity scores at week-3 (p = .061) and week-4 (p = .029).Conclusion: In conclusion, cannabis, alcohol and cigarette use were prevalent in the acute period post-concussion; however, were not observed to impact recovery within the first 4 weeks post-injury. Amongst unrecovered individuals, acute cannabis use was associated with lower symptom burden, while cigarette use was associated with greater initial symptom burden.

Stress, mindfulness, and the allergic patient

INTRODUCTION

The global incidence and prevalence of allergic diseases are increasing as is the intensity and duration of excessive psychological stress due to multiple factors associated with living in today's world such as personal, social and political unrest, increased fear and anxiety, and/or depression often leading to hopelessness. Both allergy and chronic psychological stress are characterized by immune imbalances that have similar characteristics. Thus, it is reasonable to posit that the two are interactive and stress may induce as well as complicate at least some allergic diseases. Areas covered: Stress management/reduction has been proposed with various physical, pharmacological, and psychological interventions for both preventive and therapeutic reasons. A useful intervention involves mindfulness techniques, which allow the individual to put their life situation in context for better personal management. Expert commentary: Future studies must be developed that will further examine the role of excess psychological stress in specific allergic diseases and evaluate the effectiveness of various stress intervention protocols, particularly those involving mindfulness, to determine which individual would best respond clinically to which intervention. When this is accomplished, assessment and treatment of psychological stress will become a standard component of clinical care for allergy, asthma, and other immune-based diseases.

Repeated social defeat-induced neuroinflammation, anxiety-like behavior and resistance to fear extinction were attenuated by the cannabinoid receptor agonist WIN55,212-2

Psychosocial stress contributes to the development of psychiatric disorders. Repeated social defeat (RSD) is a murine stressor that causes a release of inflammatory monocytes into circulation. Moreover, RSD-induced anxiety-like behavior is dependent on the recruitment of these monocytes to the brain. Activation of the endocannabinoid (ECB) system may modulate both neuroendocrine and inflammatory responses mediated by stress. Therefore, we hypothesized that a cannabinoid receptor agonist would attenuate RSD-induced inflammation, anxiety, and stress sensitization. To test this hypothesis, mice received an injection of the synthetic cannabinoid_1/2 receptor agonist, WIN55,212-2 (WIN; 1 mg/kg, intraperitoneally) daily for six consecutive days, 30 min before each exposure to RSD. Anxiety-like behavior, immune activation, neuroinflammation, and microglial reactivity were determined 14 h after RSD. RSD-induced anxiety-like behavior in the open field and in the EPM was reversed by WIN55,212-2. Moreover, WIN55,212-2 reduced the accumulation of inflammatory monocytes in circulation and brain after RSD and attenuated RSD-induced interleukin-1β (IL-1β) messenger RNA (mRNA) expression in microglia/macrophages. Increased ex vivo reactivity of microglia/monocytes to lipopolysaccharides (LPS) after RSD was also attenuated by WIN55,212-2. Next, fear expression, extinction, and recall were evaluated 24 and 48 h, respectively, after contextual fear conditioning, which took place 7 days after RSD. Here, RSD caused prolonged fear expression and impaired fear extinction recall, which was associated with increased IL-1β mRNA in the brain. Moreover, these stress-induced effects were reversed by WIN55,212-2. In conclusion, activation of cannabinoid receptors limited the immune and neuroinflammatory responses to RSD and reversed the short-term and long-term behavioral deficits associated with RSD.

Endocannabinoids in Body Weight Control

Maintenance of body weight is fundamental to maintain one's health and to promote longevity. Nevertheless, it appears that the global obesity epidemic is still constantly increasing. Endocannabinoids (eCBs) are lipid messengers that are involved in overall body weight control by interfering with manifold central and peripheral regulatory circuits that orchestrate energy homeostasis. Initially, blocking of eCB signaling by first generation cannabinoid type 1 receptor (CB1) inverse agonists such as rimonabant revealed body weight-reducing effects in laboratory animals and men. Unfortunately, rimonabant also induced severe psychiatric side effects. At this point, it became clear that future cannabinoid research has to decipher more precisely the underlying central and peripheral mechanisms behind eCB-driven control of feeding behavior and whole body energy metabolism. Here, we will summarize the most recent advances in understanding how central eCBs interfere with circuits in the brain that control food intake and energy expenditure. Next, we will focus on how peripheral eCBs affect food digestion, nutrient transformation and energy expenditure by interfering with signaling cascades in the gastrointestinal tract, liver, pancreas, fat depots and endocrine glands. To finally outline the safe future potential of cannabinoids as medicines, our overall goal is to address the molecular, cellular and pharmacological logic behind central and peripheral eCB-mediated body weight control, and to figure out how these precise mechanistic insights are currently transferred into the development of next generation cannabinoid medicines displaying clearly improved safety profiles, such as significantly reduced side effects.

The Endocannabinoid System, Aggression, and the Violence of Synthetic Cannabinoid Use, Borderline Personality Disorder, Antisocial Personality Disorder, and Other Psychiatric Disorders

Endogenous and exogenous cannabinoids bind to central cannabinoid receptors to control a multitude of behavioral functions, including aggression. The first main objective of this review is to dissect components of the endocannabinoid system, including cannabinoid 1 and cannabinoid 2 receptors; the endogenous cannabinoids anandamide and 2-arachidonoylglycerol; and the indirect cannabinoid modulators fatty acid amide hydrolase and monoacylglycerol lipase; that have shown abnormalities in basic research studies investigating mechanisms of aggression. While most human research has concluded that the active ingredient of marijuana, Δ9-tetrahydrocannabinol, tends to dampen rather than provoke aggression in acute doses, recent evidence supports a relationship between the ingestion of synthetic cannabinoids and emergence of violent or aggressive behavior. Thus, another objective is to evaluate the emerging clinical data. This paper also discusses the relationship between prenatal and perinatal exposure to cannabis as well as use of cannabis in adolescence on aggressive outcomes. A final objective of the paper is to discuss endocannabinoid abnormalities in psychotic and affective disorders, as well as clinically aggressive populations, such as borderline personality disorder and antisocial personality disorder. With regard to the former condition, decreased anandamide metabolites have been reported in the cerebrospinal fluid, while some preliminary evidence suggests that fatty acid amide hydrolase genetic polymorphisms are linked to antisocial personality disorder and impulsive-antisocial psychopathic traits. To summarize, this paper will draw upon basic and clinical research to explain how the endocannabinoid system may contribute to the genesis of aggressive behavior.

Signaling pathways to and from the hypophysial pars tuberalis, an important center for the control of seasonal rhythms

Seasonal (circannual) rhythms play an important role for the control of body functions (reproduction, metabolism, immune responses) in nearly all living organisms. Also humans are affected by the seasons with regard to immune responses and mental functions, the seasonal affective disorder being one of the most prominent examples. The hypophysial pars tuberalis (PT), an important interface between the hypophysial pars distalis and neuroendocrine centers in the brain, plays an essential role in the regulation of seasonal functions and may even be the seat of the circannual clock. Photoperiodic signals provide a major input to the PT. While the perception of these signals involves extraocular photoreceptors in non-mammalian species (birds, fish), mammals perceive photoperiodic signals exclusively in the retina. A multisynaptic pathway connects the retina with the pineal organ where photoperiodic signals are translated into the neurohormone melatonin that is rhythmically produced night by night and encodes the length of the night. Melatonin controls the functional activity of the mammalian PT by acting upon MT1 melatonin receptors. The PT sends its output signals via retrograde and anterograde pathways. The retrograde pathway targetting the hypothalamus employs TSH as messenger and controls a local hypothalamic T3 system. As discovered in Japanese quail, TSH triggers molecular cascades mediating thyroid hormone conversion in the ependymal cell layer of the infundibular recess of the third ventricle. The local accumulation of T₃ in the mediobasal hypothalamus (MBH) appears to activate the gonadal axis by affecting the neuro-glial interaction between GnRH terminals and tanycytes in the median eminence. This retrograde pathway is conserved in photoperiodic mammals (sheep and hamsters), and even in non-photoperiodic laboratory mice provided that they are capable to synthesize melatonin. The anterograde pathway is implicated in the control of prolactin secretion, targets cells in the PD and supposedly employs small molecules as signal substances collectively denominated as "tuberalins". Several "tuberalin" candidates have been proposed, such as tachykinins, the secretory protein TAFA and endocannabinoids (EC). The PT-intrinsic EC system was first demonstrated in Syrian hamsters and shown to respond to photoperiodic changes. Subsequently, the EC system was also demonstrated in the PT of mice, rats and humans. To date, 2-arachidonoylglycerol (2-AG) appears as the most important endocannabinoid from the PT. Likely targets for the EC are folliculo-stellate cells that contain the CB1 receptor and appear to contact lactotroph cells. The CB1 receptor was also found on corticotroph cells which appear as a further target of the EC. Recently, the CB1 receptor was also localized to CRF-containing nerve fibers running in the outer zone of the median eminence. This finding suggests that the EC system of the PT contributes not only to the anterograde, but also to the retrograde pathway. Taken together, the results support the concept that the PT transmits its signals via a "cocktail" of messenger molecules which operate also in other brain areas and systems rather than through PT-specific "tuberalins". Furthermore, they may attribute a novel function to the PT, namely the modulation of the stress response and immune functions.

Pharmacological augmentation of endocannabinoid signaling reduces the neuroendocrine response to stress

Activation of the hypothalamic-pituitary-adrenal axis (HPA) is critical for survival when the organism is exposed to a stressful stimulus. The endocannabinoid system (ECS) is currently considered an important neuromodulator involved in numerous pathophysiological processes and whose primary function is to maintain homeostasis. In the tissues constituting the HPA axis, all the components of the ECS are present and the activation of this system acts in parallel with changes in the activity of numerous neurotransmitters, including nitric oxide (NO). NO is widely distributed in the brain and adrenal glands and recent studies have shown that free radicals, and in particular NO, may play a crucial role in the regulation of stress response. Our objective was to determine the participation of the endocannabinoid and NOergic systems as probable mediators of the neuroendocrine HPA axis response to a psychophysical acute stress model in the adult male rat. Animals were pre-treated with cannabinoid receptors agonists and antagonists at central and systemic level prior to acute restraint exposure. We also performed in vitro studies incubating adrenal glands in the presence of ACTH and pharmacological compounds that modifies ECS components. Our results showed that the increase in corticosterone observed after acute restraint stress is blocked by anandamide administered at both central and peripheral level. At hypothalamic level both cannabinoid receptors (CB1 and CB2) are involved, while in the adrenal gland, anandamide has a very potent effect in suppressing ACTH-induced corticosterone release that is mainly mediated by vanilloid TRPV1 receptors. We also observed that stress significantly increased hypothalamic mRNA levels of CB1 as well as adrenal mRNA levels of TRPV1 receptor. In addition, anandamide reduced the activity of the nitric oxide synthase enzyme during stress, indicating that the anti-stress action of endocannabinoids may involve a reduction in NO production at hypothalamic and adrenal levels. In conclusion, an endogenous cannabinoid tone maintains the HPA axis in a stable basal state, which is lost with a noxious stimulus. In this case, the ECS dampens the response to stress allowing the recovery of homeostasis. Moreover, our work further contributes to in vitro evidence for a participation of the endocannabinoid system by inhibiting corticosterone release directly at the adrenal gland level.

Electroconvulsive therapy enhances endocannabinoids in the cerebrospinal fluid of patients with major depression: a preliminary prospective study

Despite the lack of clinical data about the role of the endocannabinoid system (ECS) in affective disorders, preclinical work suggests that the ECS is relevant in both with regard to the etiology of depression as well as the mediation of antidepressant effects. We measured the intraindividual levels of the endocannabinoids N-arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG) in the cerebrospinal fluid of 12 patients suffering from a major depressive episode before and after the antidepressant treatment by electroconvulsive therapy (ECT). AEA was significantly elevated after ECT as compared to baseline. The AEA increase positively correlated with the number of individually performed ECT sessions. Although the sample size was small and confounders were not rigorously controlled for, our finding corroborates preclinical work and should encourage further exploration of the involvement of the ECS in depressive disorder.

Visceral Inflammation and Immune Activation Stress the Brain

Stress refers to a dynamic process in which the homeostasis of an organism is challenged, the outcome depending on the type, severity, and duration of stressors involved, the stress responses triggered, and the stress resilience of the organism. Importantly, the relationship between stress and the immune system is bidirectional, as not only stressors have an impact on immune function, but alterations in immune function themselves can elicit stress responses. Such bidirectional interactions have been prominently identified to occur in the gastrointestinal tract in which there is a close cross-talk between the gut microbiota and the local immune system, governed by the permeability of the intestinal mucosa. External stressors disturb the homeostasis between microbiota and gut, these disturbances being signaled to the brain via multiple communication pathways constituting the gut-brain axis, ultimately eliciting stress responses and perturbations of brain function. In view of these relationships, the present article sets out to highlight some of the interactions between peripheral immune activation, especially in the visceral system, and brain function, behavior, and stress coping. These issues are exemplified by the way through which the intestinal microbiota as well as microbe-associated molecular patterns including lipopolysaccharide communicate with the immune system and brain, and the mechanisms whereby overt inflammation in the GI tract impacts on emotional-affective behavior, pain sensitivity, and stress coping. The interactions between the peripheral immune system and the brain take place along the gut-brain axis, the major communication pathways of which comprise microbial metabolites, gut hormones, immune mediators, and sensory neurons. Through these signaling systems, several transmitter and neuropeptide systems within the brain are altered under conditions of peripheral immune stress, enabling adaptive processes related to stress coping and resilience to take place. These aspects of the impact of immune stress on molecular and behavioral processes in the brain have a bearing on several disturbances of mental health and highlight novel opportunities of therapeutic intervention.

Effects of the antipsychotic paliperidone on stress-induced changes in the endocannabinoid system in rat prefrontal cortex

Objectives There is a need to explore novel mechanisms of action of existing/new antipsychotics. One potential candidate is the endocannabinoid system (ECS). The present study tried to elucidate the effects of the antipsychotic paliperidone on stress-induced ECS alterations. Methods Wister rats were submitted to acute/chronic restraint stress. Paliperidone (1 mg/kg) was given prior each stress session. Cannabinoid receptors and endocannabinoids (eCBs) synthesis and degradation enzymes were measured in prefrontal cortex (PFC) samples by RT-PCR and Western Blot. Results In the PFC of rats exposed to acute stress, paliperidone increased CB1 receptor (CB1R) expression. Furthermore, paliperidone increased the expression of the eCB synthesis enzymes N-acylphosphatidylethanolamine- hydrolysing phospholipase D and DAGLα, and blocked the stress-induced increased expression of the degrading enzyme fatty acid amide hydrolase. In chronic conditions, paliperidone prevented the chronic stress-induced down-regulation of CB1R, normalised DAGLα expression and reverted stress-induced down-regulation of the 2-AG degrading enzyme monoacylglycerol lipase. ECS was analysed also in periphery. Acute stress decreased DAGLα expression, an effect prevented by paliperidone. Contrarily, chronic stress increased DAGLα and this effect was potentiated by paliperidone. Conclusions The results obtained described a preventive effect of paliperidone on stress-induced alterations in ECS. Considering the diverse alterations on ECS described in psychotic disease, targeting ECS emerges as a new therapeutic possibility.

MAGL inhibition modulates gastric secretion and motility following NSAID exposure in mice

Non-steroidal anti-inflammatory drugs (NSAIDs) are common analgesic drugs that also cause well-known, negative gastrointestinal (GI) side effects. The physiological mechanism(s) of NSAID-induced GI damage are unclear and are likely due to multiple causes. The most studied contributing mechanisms are increased gastric acid secretion and increased gastric motility. The present study was designed to determine which ulcerogenic effects of the NSAID diclofenac sodium are reversed by blocking the endocannabinoid catabolic enzyme monoacylglycerol lipase (MAGL). Both male and female mice were used to identify possible sex differences. We hypothesized that the MAGL inhibitor JZL184 would attenuate diclofenac-induced increases in both gastric acid secretion and gastric motility. Diclofenac dose-dependently induced gastric hemorrhages to a similar extent in both male and female mice. Gastric hemorrhage severity significantly correlated with gastric levels of myeloperoxidase, an objective measure of neutrophil infiltration. Similarly, JZL184 reduced gastric acidity, in controls as well as mice treated with pentagastrin, which stimulates gastric acid release. As hypothesized, JZL184 decreased gastric motility. Surprisingly, diclofenac also slowed gastric emptying, indicating that diclofenac-induced ulcers most likely occur through increased gastric acid secretion, and not increased gastric motility, as measured in the present study. Thus, MAGL inhibition may proffer gastroprotection through modulating the secretory pathway of gastric hemorrhage. These data underscore the importance of sampling multiple time points and using both sexes in research, in addition to multiple mechanistic targets, and contribute to the basic understanding of NSAID-induced gastric inflammation.

Host-probiotic interaction: new insight into the role of the endocannabinoid system by in vivo and ex vivo approaches

The endocannabinoid system plays an important role in regulating inflammation in several chronic or anomalous gut inflammatory diseases. In vivo and ex vivo studies showed that 30 days treatment with a probiotic mix activated the endocannabinoid system in zebrafish. These results highlight the potential of this probiotic mixture to regulate immune cell function, by inducing gene expression of toll-like receptors and other immune related molecules. Furthermore, TUNEL assay showed a decrease in the number of apoptotic cells, and this finding was supported by a reduction in pro-apoptotic factors and an increase in anti-apoptotic molecules. The results presented here strengthen the molecular mechanisms activated by probiotic mix controlling immune response and inflammation.

Antinociceptive fatty acid patterns differ in children with psychosomatic recurrent abdominal pain and healthy controls

AIM

Stress is considered to trigger psychosomatic recurrent abdominal pain (RAP), but the mechanism behind the pain is unclear. Because the essential fatty acids, omega-6 and omega-3, are involved in pain, by regulating lipid mediators, we analysed the fatty acid patterns in children with RAP compared to healthy children.

METHODS

This was a cross-sectional study of plasma phospholipid fatty acids in 22 consecutively included children with RAP, aged six to 16 years, at an outpatient clinic specialising in RAP. The controls were 100 healthy children previously reported on and analysed in the same laboratory.

RESULTS

The children with psychosomatic RAP showed higher mean concentrations of saturated fatty acids than the controls (49.0 mol% versus 47.4 mol%) but lower mean levels of polyunsaturated fatty acids (38.6 mol% versus 39.9 mol%). Omega-3 fatty acids were lower in children with psychosomatic RAP, resulting in higher ratios of linoleic to alpha-linolenic acids (p < 0.001) and arachidonic to eicosapentaenoic acids (p = 0.01), despite a lower concentration of arachidonic acid in children with RAP (p < 0.01).

CONCLUSION

The results suggested an imbalance between nociceptive omega-6 fatty acids and antinociceptive omega-3 fatty acids in psychosomatic RAP. Further studies, including lipid mediators and oxidative products, are necessary to confirm an association.

Uremic Pruritus Is Not Associated with Endocannabinoid Receptor 1 Gene Polymorphisms

Uremic pruritus (UP) is a frequent and bothersome symptom in hemodialysis patients. Its etiology is not fully understood and that is why there is no specific treatment. The endocannabinoid system plays a role in many pathological conditions. There is reliable evidence on the association between cannabinoid system and pruritus. In our study, we aimed to evaluate whether genetic variations in the endocannabinoid receptor 1 (CNR1) gene can affect UP. The rs12720071, rs806368, rs1049353, rs806381, rs10485170, rs6454674, and rs2023239 polymorphisms of the CNR1 gene were genotyped in 159 hemodialysis patients and 150 healthy controls using two multiplex polymerase chain reactions and the minisequencing technique. No statistically significant relationship was found in any of the evaluated genotypes between patients with and without UP, even after excluding patients with diabetes and dyslipidemia. There were no differences between patients with UP and the control group. However, in the group of all HD patients, a significantly higher incidence of GA genotype and lower incidence in GG genotype in the polymorphism rs806381s were revealed versus the control group (p = 0.04). It seems that polymorphisms of the CNR1 gene are not associated with uremic pruritus.

Cardioprotective effects of fatty acid amide hydrolase inhibitor URB694, in a rodent model of trait anxiety

In humans, chronic anxiety represents an independent risk factor for cardiac arrhythmias and sudden death. Here we evaluate in male Wistar rats bred for high (HAB) and low (LAB) anxiety-related behavior, as well as non-selected (NAB) animals, the relationship between trait anxiety and cardiac electrical instability and investigate whether pharmacological augmentation of endocannabinoid anandamide-mediated signaling exerts anxiolytic-like and cardioprotective effects. HAB rats displayed (i) a higher incidence of ventricular tachyarrhythmias induced by isoproterenol, and (ii) a larger spatial dispersion of ventricular refractoriness assessed by means of an epicardial mapping protocol. In HAB rats, acute pharmacological inhibition of the anandamide-degrading enzyme, fatty acid amide hydrolase (FAAH), with URB694 (0.3 mg/kg), (i) decreased anxiety-like behavior in the elevated plus maze, (ii) increased anandamide levels in the heart, (iii) reduced isoproterenol-induced occurrence of ventricular tachyarrhythmias, and (iv) corrected alterations of ventricular refractoriness. The anti-arrhythmic effect of URB694 was prevented by pharmacological blockade of the cannabinoid type 1 (CB₁), but not of the CB₂, receptor. These findings suggest that URB694 exerts anxiolytic-like and cardioprotective effects in HAB rats, the latter via anandamide-mediated activation of CB₁ receptors. Thus, pharmacological inhibition of FAAH might be a viable pharmacological strategy for the treatment of anxiety-related cardiac dysfunction.

Antidepressant-like activity and cardioprotective effects of fatty acid amide hydrolase inhibitor URB694 in socially stressed Wistar Kyoto rats

In humans, depression is often triggered by prolonged exposure to psychosocial stressors and is often associated with cardiovascular comorbidity. Mounting evidence suggests a role for endocannabinoid signaling in the regulation of both emotional behavior and cardiovascular function. Here, we examined cardiac activity in a rodent model of social stress-induced depression and investigated whether pharmacological inhibition of the enzyme fatty acid amide hydrolase (FAAH), which terminates signaling of the endocannabinoid anandamide, exerts antidepressant-like and cardioprotective effects. Male Wistar Kyoto rats were exposed to five weeks of repeated social stress or control procedure. Starting from the third week, they received daily administration of the selective FAAH inhibitor URB694 (0.1 mg/kg, i.p.) or vehicle. Cardiac electrical activity was recorded by radiotelemetry. Repeated social stress triggered biological and behavioral changes that mirror symptoms of human depression, such as (i) reductions in body weight gain and sucrose solution preference, (ii) hyperactivity of the hypothalamic-pituitary-adrenocortical axis, and (iii) increased immobility in the forced swim test. Moreover, stressed rats showed (i) alterations in heart rate daily rhythm and cardiac autonomic neural regulation, (ii) a larger incidence of spontaneous arrhythmias, and (iii) signs of cardiac hypertrophy. Daily treatment with URB694 (i) increased central and peripheral anandamide levels, (ii) corrected stress-induced alterations of biological and behavioral parameters, and (iii) protected the heart against the adverse effects of social stress. Repeated social stress in Wistar Kyoto rats reproduces aspects of human depression/cardiovascular comorbidity. Pharmacological enhancement of anandamide signaling might be a promising strategy for the treatment of these comorbid conditions.

Genetic deletion of monoacylglycerol lipase leads to impaired cannabinoid receptor CB₁R signaling and anxiety-like behavior

Endocannabinoids (eCB) are key regulators of excitatory/inhibitory neurotransmission at cannabinoid-1-receptor (CB1 R)-expressing axon terminals. The most abundant eCB in the brain, that is 2-arachidonoylglycerol (2-AG), is hydrolyzed by the enzyme monoacylglycerol lipase (MAGL), whose chronic inhibition in the brain was reported to cause CB1 R desensitization. We employed the MAGL knock-out mouse (MAGL-/-), a genetic model of congenital and sustained elevation of 2-AG levels in the brain, to provide morphological and biochemical evidence for β-arrestin2-mediated CB1 R desensitization in brain regions involved in the control of emotional states, that is, the prefrontal cortex (PFC), amygdala, hippocampus and cerebellar cortex. We found a widespread CB1 R/β-arrestin2 co-expression in the mPFC, amygdala and hippocampus accompanied by impairment of extracellular signal-regulated kinase signaling and elevation of vesicular glutamate transporter (VGluT1) at CB1 R-positive excitatory terminals in the mPFC, or vesicular GABA transporter (VGAT) at CB1 R-positive inhibitory terminals in the amygdala and hippocampus. The impairment of CB1 R signaling in MAGL-/- mice was also accompanied by enhanced excitatory drive in the basolateral amygdala (BLA)-mPFC circuit, with subsequent elevation of glutamate release to the mPFC and anxiety-like and obsessive-compulsive behaviors, as assessed by the light/dark box and marble burying tests, respectively. Collectively, these data provide evidence for a β-arrestin2-mediated desensitization of CB1 R in MAGL-/- mice, with impact on the synaptic plasticity of brain circuits involved in emotional functions. In this study, the authors provide evidence that congenitally enhanced endocannabinoid levels in the neuronal circuits underlying anxiety-like behavioral states (mainly medial prefrontal cortex, amygdala and hippocampus) lead to CB1R desenistization and anxiety and depression. MAGL-/- mice, a model of congenital overactivity of the eCB system, exhibited a compensatory impairment of CB1R signaling in anxiety-associated brain areas and a subsequent change in excitatory/inhibitory tone associated with altered score in the marble burying and light/dark box test, in concomitance with anxiety and depression behavior states. These findings may have potential relevance to the understanding of the neurochemical effects of chronic CB1R overstimulation in cannabis abusers.

A cannabinoid receptor 1 polymorphism is protective against major depressive disorder in methadone-maintained outpatients

BACKGROUND AND OBJECTIVES

The burden of opiate dependence not only relies on somatic complications such as infectious diseases or acute intoxication but also on frequent psychiatric events such as major depressive disorder (MDD) and suicidal behavior (SB). Given the preclinical and clinical evidence regarding the associations between cannabinoid systems and both opiate dependence and psychiatric disorders, we chose to address whether one single nucleotide polymorphism (SNP) of the cannabinoid receptor type 1 gene (CNR1) named rs2023239 would be associated with lifetime MDD and SB in a population of opiate-dependent outpatients remitted under stable methadone treatment.

METHODS

Sociodemographic and clinical data were included as independent factors in two logistic regression models aimed at predicting SB and MDD, respectively, performed with 85 Caucasian individuals.

RESULTS

The minor C allele of rs2023239 showed an independent protective effect against lifetime MDD after adjustment for potential confounders. It was not associated with variables related to suicidal behavior.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

Despite limitations due to the modest sample size, our results are consistent with previous research on the endocannabinoid system and suggest new leads for detecting subjects at risk of MDD, which remains insufficiently diagnosed and treated in patients suffering from severe addictive disorders.

Controlled Release of Salicylic Acid from Biodegradable Cross-Linked Polyesters

The purpose of this work was to develop a family of cross-linked poly(xylitol adipate salicylate)s with a wide range of tunable release properties for delivering pharmacologically active salicylic acid. The synthesis parameters and release conditions were varied to modulate polyester properties and to understand the mechanism of release. Varying release rates were obtained upon longer curing (35% in the noncured polymer to 10% in the cured polymer in 7 days). Differential salicylic acid loading led to the synthesis of polymers with variable cross-linking and the release could be tuned (100% release for the lowest loading to 30% in the highest loading). Controlled release was monitored by changing various factors, and the release profiles were dependent on the stoichiometric composition, pH, curing time, and presence of enzyme. The polymer released a combination of salicylic acid and disalicylic acid, and the released products were found to be nontoxic. Minimal hemolysis and platelet activation indicated good blood compatibility. These polymers qualify as "bioactive" and "resorbable" and can, therefore, find applications as immunomodulatory resorbable biomaterials with tunable release properties.

Preclinical evaluation of SMM-189, a cannabinoid receptor 2-specific inverse agonist

Cannabinoid receptor 2 agonists and inverse agonists are emerging as new therapeutic options for a spectrum of autoimmune-related disease. Of particular interest, is the ability of CB2 ligands to regulate microglia function in neurodegenerative diseases and traumatic brain injury. We have previously reported the receptor affinity of 3',5'-dichloro-2,6-dihydroxy-biphenyl-4-yl)-phenyl-methanone (SMM-189) and the characterization of the beneficial effects of SMM-189 in the mouse model of mild traumatic brain injury. Herein, we report the further characterization of SMM-189 as a potent and selective CB2 inverse agonist, which acts as a noncompetitive inhibitor of CP 55,940. The ability of SMM-189 to regulate microglial activation, in terms of chemokine expression and cell morphology, has been determined. Finally, we have determined that SMM-189 possesses acceptable biopharmaceutical properties indicating that the triaryl class of CB2 inverse agonists are viable compounds for continued preclinical development for the treatment of neurodegenerative disorders and traumatic brain injury.

Emerging drugs for the treatment of anxiety

INTRODUCTION

Anxiety disorders are among the most prevalent and disabling psychiatric disorders in the United States and worldwide. Basic research has provided critical insights into the mechanism regulating fear behavior in animals and a host of animal models have been developed in order to screen compounds for anxiolytic properties. Despite this progress, no mechanistically novel agents for the treatment of anxiety have come to market in more than two decades.

AREAS COVERED

The current review will provide a critical summary of current pharmacological approaches to the treatment of anxiety and will examine the pharmacotherapeutic pipeline for treatments in development. Anxiety and related disorders considered herein include panic disorder, social anxiety disorder, generalized anxiety disorder and post-traumatic stress disorder. The glutamate, neuropeptide and endocannabinoid systems show particular promise as future targets for novel drug development.

EXPERT OPINION

In the face of an ever-growing understanding of fear-related behavior, the field awaits the translation of this research into mechanistically novel treatments. Obstacles will be overcome through close collaboration between basic and clinical researchers with the goal of aligning valid endophenotypes of human anxiety disorders with improved animal models. Novel approaches are needed to move basic discoveries into new, more effective treatments for our patients.

Endogenous opioids: opposing stress with a cost

The stress response is characterized by the coordinated engagement of central and peripheral neural systems in response to life-threatening challenges. It has been conserved through evolution and is essential for survival. However, the frequent or continual elicitation of the stress response by repeated or chronic stress, respectively, results in the dysfunction of stress response circuits, ultimately leading to stress-related pathology. In an effort to best respond to stressors, yet at the same time maintain homeostasis and avoid dysfunction, stress response systems are finely balanced and co-regulated by neuromodulators that exert opposing effects. These opposing systems serve to restrain certain stress response systems and promote recovery. However, the engagement of opposing systems comes with the cost of alternate dysfunctions. This review describes, as an example of this dynamic, how endogenous opioids function to oppose the effects of the major stress neuromediator, corticotropin-releasing hormone, and promote recovery from a stress response and how these actions can both protect and be hazardous to health.

Endogenous Opioids: The Downside of Opposing Stress

Our dynamic environment regularly exposes us to potentially life-threatening challenges or stressors. To answer these challenges and maintain homeostasis, the stress response, an innate coordinated engagement of central and peripheral neural systems is initiated. Although essential for survival, the inappropriate initiation of the stress response or its continuation after the stressor is terminated has pathological consequences that have been linked to diverse neuropsychiatric and medical diseases. Substantial individual variability exists in the pathological consequences of stressors. A theme of this Special Issue is that elucidating the basis of individual differences in resilience or its flipside, vulnerability, will greatly advance our ability to prevent and treat stress-related diseases. This can be approached by studying individual differences in "pro-stress" mediators such as corticosteroids or the hypothalamic orchestrator of the stress response, corticotropin-releasing factor. More recently, the recognition of endogenous neuromodulators with "anti-stress" activity that have opposing actions or that restrain stress-response systems suggests additional bases for individual differences in stress pathology. These "anti-stress" neuromodulators offer alternative strategies for manipulating the stress response and its pathological consequences. This review uses the major brain norepinephrine system as a model stress-response system to demonstrate how co-regulation by opposing pro-stress (corticotropin-releasing factor) and anti-stress (enkephalin) neuromodulators must be fine-tuned to produce an adaptive response to stress. The clinical consequences of tipping this fine-tuned balance in the direction of either the pro- or anti-stress systems are emphasized. Finally, that each system provides multiple points at which individual differences could confer stress vulnerability or resilience is discussed.

Comparative biochemical characterization of the monoacylglycerol lipase inhibitor KML29 in brain, spinal cord, liver, spleen, fat and muscle tissue

Monoacylglycerol lipase (MAGL) is part of the endocannabinoid and the prostaglandin signaling system. MAGL degrades the endocannabinoid 2-arachidonoylglycerol (2-AG) into glycerol and arachidonic acid. MAGL-induced arachidonic acid is the primary source for prostaglandin synthesis in the brain. 2-AG mainly induces neuroprotective and anti-inflammatory effects, whereas prostaglandins are related to pro-inflammatory effects inducing neurotoxicity. Therefore, inhibition of MAGL represents a promising target for neurological diseases characterized by inflammation. However, as 2-AG is an agonist for the cannabinoid receptor 1 (CB1), inhibition of MAGL might be associated with unwanted cannabimimetic effects. Here, we show that oral administration of KML29, a highly selective inhibitor of MAGL, induced large and dose-dependent changes in 2-AG levels in vivo in brain and spinal cord of mice. Of note, MAGL inhibition by KML29 induced a decrease in prostaglandin levels in brain and most peripheral tissues but not in the spinal cord. MAGL expression was highest in fat, liver and brain, whereas the cytosolic phospholipase A2 (cPLA2), a further enzyme responsible for arachidonic acid production, was highly expressed in spinal cord, muscle and spleen. In addition, high doses (10 mg/kg) of KML29 induced some cannabimimetic effects in vivo in the tetrad test, including hypothermia, analgesia and hypomotility without induction of cataleptic behavior. In summary, inhibition of MAGL by KML29 represents a promising strategy for targeting the cannabinoid and prostaglandin system of the brain with only a moderate induction of cannabimimetic effects.