Oleamide is a selective endogenous agonist of rat and human CB1 cannabinoid receptors

Assessment of using heart of date palm as a new source of protein and carbohydrate on the quality of low-fat bio fermented camel milk and its potential anticancer properties

The heart of date palm (HDP) is a nutrient-dense vegetable, rich in protein and carbohydrate, obtained from the core of palm trees. Carbohydrates are the major component of the heart of date palm, providing a quick source of energy and fiber content can help digestion and contribute to feeling of fullness, making it good addition to a balanced diet. The study investigated the potential of incorporating HDP into low-fat bio fermented camel milk (BCM). The initial findings highlighted HDP's medicinal properties and its significant cytotoxic effects against HepG2 cells, indicating its potential as an anticancer agent. Over 21 days of cold storage, the addition of HDP improved the water-holding capacity, color, sensory qualities, bioactive compounds, and rheological properties of low-fat BCM. Moreover, no mold, yeasts, or coliforms were detected in any samples throughout the storage. The total number of viable probiotic cells remained functional (>106 log CFU/g) for 21 days. The sensory evaluation results suggested that high-quality low-fat BCM can be achieved by adding up to 20 % HDP. The molecular docking study supports the various biological activities of HDP particularly in relation to its cytotoxic effects against HepG2 cancer cells. This study opens the door for further exploration into utilizing HDP as a novel functional ingredient in dairy foods to create value-added products.

Serum Metabolomics Analysis Revealed Metabolic Pathways Related to AECOPD Complicated with Anxiety and Depression

Background

Anxiety and depression are two of the most common comorbidities of COPD, which can directly lead to the number of acute exacerbations and hospitalizations of COPD patients and reduce their quality of life. At present, there are many studies on anxiety and depression in stable COPD, but few studies on anxiety and depression in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) patients.

Objective

We aim to explore the changes of serum metabolomics in AECOPD complicated with anxiety and depression and to provide some clues for further understanding its pathogenesis.

Methods

This is an observational high-throughput experimental study based on retrospective data extraction. Twenty-one AECOPD with anxiety and depressive patients and 17 healthy controls (HCs) were retrospectively enrolled in the Second Affiliated Hospital of Anhui Medical University. Hamilton anxiety scale (HAMA) and Hamilton depression scale (HAMD) for anxiety and depression were used to assess the patients with AECOPD. Untargeted metabolomics analysis was carried out to investigate different molecules in the serum of all participants. General information of all participants, baseline data and clinical measurement data of AECOPD patients were collected. Statistical analysis and bioinformatics analysis were performed to reveal different metabolites and perturbed metabolic pathways.

Results

A total of 724 metabolites in positive ionization mode and 555 metabolites in negative ionization mode were different in AECOPD patients with anxiety and depression. The 1,279 serum metabolites could be divided into 77 categories. Based on multivariate and univariate analysis, 74 metabolites were detected in positive ionization mode, and 60 metabolites were detected in negative ionization as differential metabolites. The 134 metabolites were enriched in 18 pathways, including biosynthesis of unsaturated fatty acids, aldosterone synthesis and secretion, protein digestion and absorption, ovarian steroidogenesis, long-term depression, retrograde endocannabinoid signaling, and so on.

Conclusion

This work highlights the key metabolites and metabolic pathways disturbed in AECOPD patients with anxiety and depression. These findings support the use of metabolomics to understand the pathogenic mechanisms involved in AECOPD patients with anxiety and depression.

Fatty acid amides present in Camembert cheese improved cognitive decline after oral administration in mice

Herein, we investigated the effects of Camembert cheese (CC) and its fatty acid contents on cognitive function in mice by employing the object recognition test to evaluate hippocampus-dependent memory. Orally administered CC improved the cognitive decline induced by a high-fat diet. Next, we focused on myristamide (MA), oleamide, and stearamide, which are fatty acid amides produced during the fermentation process of CC. We found that oral administration of MA improved cognitive decline. Notably, an improvement was not observed using myristic acid, a free fatty acid that is not amidated. Thus, fatty acid amidation may contribute to the physiological activity. Moreover, we investigated changes in gene expression related to neurogenesis in the hippocampus. After MA administration, mRNA expression analysis indicated that MA increased hippocampal brain-derived neurotrophic factor expression.

Acute exposure of zebrafish (Danio rerio) adults to psychotria carthagenensis leaf extracts: chemical profile, lack of genotoxicity and histological changes

Psychotria carthagenensis is a shrubby plant, often consumed by traditional populations in religious rituals. Previous studies have shown that this plant's infusion can inhibit the activity of Acetylcholinesterase (AChE) in rats. Despite the therapeutic potential, there is a lack of research regarding its possible toxicological and genotoxic effects. Hence, this study aimed to analyze the chemical profile of the ethanol extract from P. carthagenensis leaves by LC-DAD-MS and assess its possible toxicity and genotoxicity in zebrafish (Danio rerio). Adult zebrafish (N = 9/group) were exposed at different concentrations and the LC50 was calculated. Frequencies of micronucleus (MN) and nuclear abnormalities (NA) were estimated for genotoxic effects, and degree of tissue changes (DTC) was used to assess the liver and gill histopathology. From the LC-DAD-MS analyses, the identified compounds included N-fructosyl valine, ethyl hexoside, 5-O-E-caffeoylquinic acid, N-feruloylagmatime, roseoside, di-O-deoxyhexoyl-hexosyl quercetin, loiolide, and oleamide. The calculated values of LC50 did not vary significantly during the time of exposure. At the concentrations of 1.25, 2.5, 3.75, 5, 7.5, 10 and 15 mg/L, there was no genotoxicity, and only low to moderate toxicity for the tissues was observed, despite mortality of 100% at doses of 20-100 mg/L of P. carthagenensis ethanolic leaf extract. There were changes in cytoplasm of hepatocytes at 1.25 mg/L, and karyorrhexis, karyolysis and megalocytosis at 10 mg/L. In the gills, the alterations were primary lamellar hyperplasia in all concentrations, and at 10 mg/L, secondary lamellar edema and vascular hyperemia were common. Additionally, the chemical composition of P. carthagenensis was expanded.

Cannabinoids: Emerging sleep modulator

Sleep is an essential biological phase of our daily life cycle and is necessary for maintaining homeostasis, alertness, metabolism, cognition, and other key functions across the animal kingdom. Dysfunctional sleep leads to deleterious effects on health, mood, and cognition, including memory deficits and an increased risk of diabetes, stroke, and neurological disorders. Sleep is regulated by several brain neuronal circuits, neuromodulators, and neurotransmitters, where cannabinoids have been increasingly found to play a part in its modulation. Cannabinoids, a group of lipid metabolites, are regulatory molecules that bind mainly to cannabinoid receptors (CB1 and CB2). Much evidence supports the role of cannabinoid receptors in the modulation of sleep, where their alteration exhibits sleep-promoting effects, including an increase in non-rapid-eye movement sleep and a reduction in sleep latency. However, the pharmacological alteration of CB1 receptors is associated with adverse psychotropic effects, which are not exhibited in CB2 receptor alteration. Hence, selective alteration of CB2 receptors is also of clinical importance, where it could potentially be used in treating sleep disorders. Thus, it is crucial to understand the neurobiological basis of cannabinoids in sleep physiology. In this review article, the alteration of the endocannabinoid system by various cannabinoids and their respective effects on the sleep-wake cycle are discussed based on recent findings. The mechanisms of the cannabinoid receptors on sleep and wakefulness are also explored for their clinical implications and potential therapeutic use on sleep disorders.

Goods and Bads of the Endocannabinoid System as a Therapeutic Target: Lessons Learned after 30 Years

The cannabis derivative marijuana is the most widely used recreational drug in the Western world and is consumed by an estimated 83 million individuals (∼3% of the world population). In recent years, there has been a marked transformation in society regarding the risk perception of cannabis, driven by its legalization and medical use in many states in the United States and worldwide. Compelling research evidence and the Food and Drug Administration cannabis-derived cannabidiol approval for severe childhood epilepsy have confirmed the large therapeutic potential of cannabidiol itself, Δ9-tetrahydrocannabinol and other plant-derived cannabinoids (phytocannabinoids). Of note, our body has a complex endocannabinoid system (ECS)-made of receptors, metabolic enzymes, and transporters-that is also regulated by phytocannabinoids. The first endocannabinoid to be discovered 30 years ago was anandamide (N-arachidonoyl-ethanolamine); since then, distinct elements of the ECS have been the target of drug design programs aimed at curing (or at least slowing down) a number of human diseases, both in the central nervous system and at the periphery. Here a critical review of our knowledge of the goods and bads of the ECS as a therapeutic target is presented to define the benefits of ECS-active phytocannabinoids and ECS-oriented synthetic drugs for human health. SIGNIFICANCE STATEMENT: The endocannabinoid system plays important roles virtually everywhere in our body and is either involved in mediating key processes of central and peripheral diseases or represents a therapeutic target for treatment. Therefore, understanding the structure, function, and pharmacology of the components of this complex system, and in particular of key receptors (like cannabinoid receptors 1 and 2) and metabolic enzymes (like fatty acid amide hydrolase and monoacylglycerol lipase), will advance our understanding of endocannabinoid signaling and activity at molecular, cellular, and system levels, providing new opportunities to treat patients.

Brain Metabolomics in Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS)

The course of pathophysiological mechanisms involved in fragile X-associated tremor/ataxia syndrome (FXTAS) remains largely unknown. Previous proteomics and metabolomics studies conducted in blood samples collected from FMR1 premutation carriers with FXTAS reported abnormalities in energy metabolism, and precursors of gluconeogenesis showed significant changes in plasma expression levels in FMR1 premutation carriers who developed FXTAS. We conducted an analysis of postmortem human brain tissues from 44 donors, 25 brains with FXTAS, and 19 matched controls. We quantified the metabolite relative abundance in the inferior temporal gyrus and the cerebellum using untargeted mass spectrometry (MS)-based metabolomics. We investigated how the metabolite type and abundance relate to the number of cytosine-guanine-guanine (CGG) repeats, to markers of neurodegeneration, and to the symptoms of FXTAS. A metabolomic analysis identified 191 primary metabolites, the data were log-transformed and normalized prior to the analysis, and the relative abundance was compared between the groups. The changes in the relative abundance of a set of metabolites were region-specific with some overlapping results; 22 metabolites showed alterations in the inferior temporal gyrus, while 21 showed differences in the cerebellum. The relative abundance of cytidine was decreased in the inferior temporal gyrus, and a lower abundance was found in the cases with larger CGG expansions; oleamide was significantly decreased in the cerebellum. The abundance of 11 metabolites was influenced by changes in the CGG repeat number. A histological evaluation found an association between the presence of microhemorrhages in the inferior temporal gyrus and a lower abundance of 2,5-dihydroxypyrazine. Our study identified alterations in the metabolites involved in the oxidative-stress response and bioenergetics in the brains of individuals with FXTAS. Significant changes in the abundance of cytidine and oleamide suggest their potential as biomarkers and therapeutic targets for FXTAS.

Scaling the Andean Shilajit: A Novel Neuroprotective Agent for Alzheimer's Disease

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder without a cure, despite the enormous number of investigations and therapeutic approaches. AD is a consequence of microglial responses to "damage signals", such as aggregated tau oligomers, which trigger a neuro-inflammatory reaction, promoting the misfolding of cytoskeleton structure. Since AD is the most prevalent cause of dementia in the elderly (>60 years old), new treatments are essential to improve the well-being of affected subjects. The pharmaceutical industry has not developed new drugs with efficacy for controlling AD. In this context, major attention has been given to nutraceuticals and novel bioactive compounds, such as molecules from the Andean Shilajit (AnSh), obtained from the Andes of Chile. Primary cultures of rat hippocampal neurons and mouse neuroblastoma cells were evaluated to examine the functional and neuroprotective role of different AnSh fractions. Our findings show that AnSh fractions increase the number and length of neuronal processes at a differential dose. All fractions were viable in neurons. The AnSh fractions inhibit tau self-aggregation after 10 days of treatment. Finally, we identified two candidate molecules in M3 fractions assayed by UPLC/MS. Our research points to a novel AnSh-derived fraction that is helpful in AD. Intensive work toward elucidation of the molecular mechanisms is being carried out. AnSh is an alternative for AD treatment or as a coadjuvant for an effective treatment.

Developmental programming: Preconceptional and gestational exposure of sheep to a real-life environmental chemical mixture alters maternal metabolome in a fetal sex-specific manner

BACKGROUND

Everyday, humans are exposed to a mixture of environmental chemicals some of which have endocrine and/or metabolism disrupting actions which may contribute to non-communicable diseases. The adverse health impacts of real-world chemical exposure, characterized by chronic low doses of a mixture of chemicals, are only recently emerging. Biosolids derived from human waste represent the environmental chemical mixtures humans are exposed to in real life. Prior studies in sheep have shown aberrant reproductive and metabolic phenotypes in offspring after maternal biosolids exposure.

OBJECTIVE

To determine if exposure to biosolids perturbs the maternal metabolic milieu of pregnant ewes, in a fetal sex-specific manner.

METHODS

Ewes were grazed on inorganic fertilizer (Control) or biosolids-treated pastures (BTP) from before mating and throughout gestation. Plasma from pregnant ewes (Control n = 15, BTP n = 15) obtained mid-gestation were analyzed by untargeted metabolomics. Metabolites were identified using Agilent MassHunter. Multivariate analyses were done using MetaboAnalyst 5.0 and confirmed using SIMCA.

RESULTS

Univariate and multivariate analysis of 2301 annotated metabolites identified 193 differentially abundant metabolites (DM) between control and BTP sheep. The DM primarily belonged to the super-class of lipids and organic acids. 15-HeTrE, oleamide, methionine, CAR(3:0(OH)) and pyroglutamic acid were the top DM and have been implicated in the regulation of fetal growth and development. Fetal sex further exacerbated differences in metabolite profiles in the BTP group. The organic acids class of metabolites was abundant in animals with male fetuses. Prenol lipid, sphingolipid, glycerolipid, alkaloid, polyketide and benzenoid classes showed fetal sex-specific responses to biosolids.

DISCUSSION

Our study illustrates that exposure to biosolids significantly alters the maternal metabolome in a fetal sex-specific manner. The altered metabolite profile indicates perturbations to fatty acid, arginine, branched chain amino acid and one‑carbon metabolism. These factors are consistent with, and likely contribute to, the adverse phenotypic outcomes reported in the offspring.

Endocannabinoid System and Exogenous Cannabinoids in Depression and Anxiety: A Review

Background: There is a growing liberalization of cannabis-based preparations for medical and recreational use. In multiple instances, anxiety and depression are cited as either a primary or a secondary reason for the use of cannabinoids. Aim: The purpose of this review is to explore the association between depression or anxiety and the dysregulation of the endogenous endocannabinoid system (ECS), as well as the use of phytocannabinoids and synthetic cannabinoids in the remediation of depression/anxiety symptoms. After a brief description of the constituents of cannabis, cannabinoid receptors and the endocannabinoid system, the most important evidence is presented for the involvement of cannabinoids in depression and anxiety both in human and from animal models of depression and anxiety. Finally, evidence is presented for the clinical use of cannabinoids to treat depression and anxiety. Conclusions: Although the common belief that cannabinoids, including cannabis, its main studied components-tetrahydrocannabinol (THC) and cannabidiol (CBD)-or other synthetic derivatives have been suggested to have a therapeutic role for certain mental health conditions, all recent systematic reviews that we report have concluded that the evidence that cannabinoids improve depressive and anxiety disorders is weak, of very-low-quality, and offers no guidance on the use of cannabinoids for mental health conditions within a regulatory framework. There is an urgent need for high-quality studies examining the effects of cannabinoids on mental disorders in general and depression/anxiety in particular, as well as the consequences of long-term use of these preparations due to possible risks such as addiction and even reversal of improvement.

Oleamide Reduces Mitochondrial Dysfunction and Toxicity in Rat Cortical Slices Through the Combined Action of Cannabinoid Receptors Activation and Induction of Antioxidant Activity

The potential treatment of neurodegenerative disorders requires the development of novel pharmacological strategies at the experimental level, such as the endocannabinoid-based therapies. The effects of oleamide (OEA), a fatty acid primary amide with activity on cannabinoid receptors, was tested against mitochondrial toxicity induced by the electron transport chain complex II inhibitor, 3-nitropropionic acid (3-NP), in rat cortical slices. OEA prevented the 3-NP-induced loss of mitochondrial function/cell viability at a concentration range of 5 nM-25 µM, and this protective effect was observed only when the amide was administered as pretreatment, but not as post-treatment. The preservation of mitochondrial function/cell viability induced by OEA in the toxic model induced by 3-NP was lost when the slices were pre-incubated with the cannabinoid receptor 1 (CB1R) selective inhibitor, AM281, or the cannabinoid receptor 2 (CB2R) selective inhibitor, JTE-907. The 3-NP-induced inhibition of succinate dehydrogenase (mitochondrial Complex II) activity was recovered by 25 nM OEA. The amide also prevented the increased lipid peroxidation and the changes in reduced/oxidized glutathione (GSH/GSSG) ratio induced by 3-NP. The cell damage induced by 3-NP, assessed as incorporation of cellular propidium iodide, was mitigated by OEA. Our novel findings suggest that the neuroprotective properties displayed by OEA during the early stages of damage to cortical cells involve the converging activation of CB1R and CB2R and the increase in antioxidant activity, which combined may emerge from the preservation of the functional integrity of mitochondria.

The Biosynthesis and Metabolism of the N-Acylated Aromatic Amino Acids: N-Acylphenylalanine, N-Acyltyrosine, N-Acyltryptophan, and N-Acylhistidine

The fatty acid amides are a family of lipids composed of two chemical moieties, a fatty acid and a biogenic amine linked together in an amide bond. This lipid family is structurally related to the endocannabinoid anandamide (N-arachidonoylethanolamine) and, thus, is frequently referred to as a family of endocannabinoid-related lipids. The fatty acid amide family is divided into different classes based on the conjugate amine; anandamide being a member of the N-acylethanolamine class (NAE). Another class within the fatty acid amide family is the N-acyl amino acids (NA-AAs). The focus of this review is a sub-class of the NA-AAs, the N-acyl aromatic amino acids (NA-ArAAs). The NA-ArAAs are not broadly recognized, even by those interested in the endocannabinoids and endocannabinoid-related lipids. Herein, the NA-ArAAs that have been identified from a biological source will be highlighted and pathways for their biosynthesis, degradation, enzymatic modification, and transport will be presented. Also, information about the cellular functions of the NA-ArAAs will be placed in context with the data regarding the identification and metabolism of these N-acylated amino acids. A review of the current state-of-knowledge about the NA-ArAAs is to stimulate future research about this underappreciated sub-class of the fatty acid amide family.

Assessment of NSAIDs as potential inhibitors of the fatty acid amide hydrolase I (FAAH-1) using three different primary fatty acid amide substrates in vitro

Background

Pain relief remains a major subject of inadequately met need of patients. Therapeutic agents designed to treat pain and inflammation so far have low to moderate efficiencies with significant untoward side effects. FAAH-1 has been proposed as a promising target for the discovery of drugs to treat pain and inflammation without significant adverse effects. FAAH-1 is the primary enzyme accountable for the degradation of AEA and related fatty acid amides. Studies have revealed that the simultaneous inhibition of COX and FAAH-1 activities produce greater pharmacological efficiency with significantly lowered toxicity and ulcerogenic activity. Recently, the metabolism of endocannabinoids by COX-2 was suggested to be differentially regulated by NSAIDs.

Methods

We analysed the affinity of oleamide, arachidonamide and stearoylamide at the FAAH-1 in vitro and investigated the potency of selected NSAIDs on the hydrolysis of endocannabinoid-like molecules (oleamide, arachidonamide and stearoylamide) by FAAH-1 from rat liver. NSAIDs were initially screened at 500 μM after which those that exhibited greater potency were further analysed over a range of inhibitor concentrations.

Results

The substrate affinity of FAAH-1 obtained, increased in a rank order of oleamide < arachidonamide < stearoylamide with resultant V_max values in a rank order of arachidonamide > oleamide > stearoylamide. The selected NSAIDs caused a concentration-dependent inhibition of FAAH-1 activity with sulindac, carprofen and meclofenamate exhibiting the greatest potency. Michaelis-Menten analysis suggested the mode of inhibition of FAAH-1 hydrolysis of both oleamide and arachidonamide by meclofenamate and indomethacin to be non-competitive in nature.

Conclusion

Our data therefore suggest potential for study of these compounds as combined FAAH-1-COX inhibitors.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40360-021-00539-1.

Cannabinoids in Breast Cancer: Differential Susceptibility According to Subtype

Although cannabinoids have been used for centuries for diverse pathological conditions, recently, their clinical interest and application have emerged due to their diverse pharmacological properties. Indeed, it is well established that cannabinoids exert important actions on multiple sclerosis, epilepsy and pain relief. Regarding cancer, cannabinoids were first introduced to manage chemotherapy-related side effects, though several studies demonstrated that they could modulate the proliferation and death of different cancer cells, as well as angiogenesis, making them attractive agents for cancer treatment. In relation to breast cancer, it has been suggested that estrogen receptor-negative (ER-) cells are more sensitive to cannabinoids than estrogen receptor-positive (ER+) cells. In fact, most of the studies regarding their effects on breast tumors have been conducted on triple-negative breast cancer (TNBC). Nonetheless, the number of studies on human epidermal growth factor receptor 2-positive (HER2+) and ER+ breast tumors has been rising in recent years. However, besides the optimistic results obtained thus far, there is still a long way to go to fully understand the role of these molecules. This review intends to help clarify the clinical potential of cannabinoids for each breast cancer subtype.

On the Biomedical Properties of Endocannabinoid Degradation and Reuptake Inhibitors: Pre-clinical and Clinical Evidence

The endocannabinoid system (ECS) is composed of endogenous cannabinoids; components involved in their synthesis, transport, and degradation; and an expansive variety of cannabinoid receptors. Hypofunction or deregulation of the ECS is related to pathological conditions. Consequently, endogenous enhancement of endocannabinoid levels and/or regulation of their metabolism represent promising therapeutic approaches. Several major strategies have been suggested for the modulation of the ECS: (1) blocking endocannabinoids degradation, (2) inhibition of endocannabinoid cellular uptake, and (3) pharmacological modulation of cannabinoid receptors as potential therapeutic targets. Here, we focused in this review on degradation/reuptake inhibitors over cannabinoid receptor modulators in order to provide an updated synopsis of contemporary evidence advancing mechanisms of endocannabinoids as pharmacological tools with therapeutic properties for the treatment of several disorders. For this purpose, we revisited the available literature and reported the latest advances regarding the biomedical properties of fatty acid amide hydrolase and monoacylglycerol lipase inhibitors in pre-clinical and clinical studies. We also highlighted anandamide and 2-arachidonoylglycerol reuptake inhibitors with promising results in pre-clinical studies using in vitro and animal models as an outlook for future research in clinical trials.

Cannabinoids: Revealing their complexity and role in central networks of fear and anxiety

The first aim of the present review is to provide an in-depth description of the cannabinoids and their known effects at various neuronal receptors. It reveals that cannabinoids are highly diverse, and recent work has highlighted that their effects on the central nervous system (CNS) are surprisingly more complex than previously recognized. Cannabinoid-sensitive receptors are widely distributed throughout the CNS where they act as primary modulators of neurotransmission. Secondly, we examine the role of cannabinoid receptors at key brain sites in the control of fear and anxiety. While our understanding of how cannabinoids specifically modulate these networks is mired by their complex interactions and diversity, a plausible framework(s) for their effects is proposed. Finally, we highlight some important knowledge gaps in our understanding of the mechanism(s) responsible for their effects on fear and anxiety in animal models and their use as therapeutic targets in humans. This is particularly important for our understanding of the phytocannabinoids used as novel clinical interventions.

Serotonin 2A receptors and cannabinoids

Accumulating evidence has proven that both exogenous cannabinoids as well as imbalances in the endocannabinoid system are involved in the onset and development of mental disorders such as anxiety, depression, or schizophrenia. Extensive recent research in this topic has mainly focused on the molecular mechanisms by which cannabinoid agonists may contribute to the pathophysiology of these disorders. Initially, serotonin neurotransmitter garnered most attention due to its relationship to mood disorders and mental diseases, with little attention to specific receptors. To date, the focus has redirected toward the understanding of different serotonin receptors, through a demonstration of its versatile pharmacology and synergy with different modulators. Serotonin 2A receptors are a good example of this phenomenon, and the complex signaling that they trigger appears of high relevance in the context of mental disorders, especially in schizophrenia. This chapter will analyze most relevant attributes of serotonin 2A receptors and the endocannabinoid system, and will highlight the evidence toward the functional bidirectional interaction between these elements in the brain as well as the impact of the endocannabinoid system dysregulation on serotonin 2A receptors functionality.

International Union of Basic and Clinical Pharmacology. CX. Classification of Receptors for 5-hydroxytryptamine; Pharmacology and Function

5-HT receptors expressed throughout the human body are targets for established therapeutics and various drugs in development. Their diversity of structure and function reflects the important role 5-HT receptors play in physiologic and pathophysiological processes. The present review offers a framework for the official receptor nomenclature and a detailed understanding of each of the 14 5-HT receptor subtypes, their roles in the systems of the body, and, where appropriate, the (potential) utility of therapeutics targeting these receptors. SIGNIFICANCE STATEMENT: This review provides a comprehensive account of the classification and function of 5-hydroxytryptamine receptors, including how they are targeted for therapeutic benefit.

Oleamide Induces Cell Death in Glioblastoma RG2 Cells by a Cannabinoid Receptor-Independent Mechanism

The endocannabinoid system has been associated with antiproliferative effects in several types of tumors through cannabinoid receptor-mediated cell death mechanisms. Oleamide (ODA) is a CB1/CB2 agonist associated with cell growth and migration by adhesion and/or ionic signals associated with Gap junctions. Antiproliferative mechanisms related to ODA remain unknown. In this work, we evaluated the effects of ODA on cell viability and morphological changes in a rat RG2 glioblastoma cell line and compared these effects with primary astrocyte cultures from 8-day postnatal rats. RG2 and primary astrocyte cultures were treated with ODA at increasing concentrations (25, 50, 100, and 200 μM) for different periods of time (12, 24, and 48 h). Changes in RG2 cell viability and morphology induced by ODA were assessed by viability/mitochondrial activity test and phase contrast microscopy, respectively. The ratios of necrotic and apoptotic cell death, and cell cycle alterations, were evaluated by flow cytometry. The roles of CB1 and CB2 receptors on ODA-induced changes were explored with specific receptor antagonists. ODA (100 μM) induced somatic damage, detachment of somatic bodies, cytoplasmic polarization, and somatic shrinkage in RG2 cells at 24 and 48 h. In contrast, primary astrocytes treated at the same ODA concentrations exhibited cell aggregation but not cell damage. ODA (100 μM) increased apoptotic cell death and cell arrest in the G1 phase at 24 h in the RG2 line. The effects induced by ODA on cell viability of RG2 cells were independent of CB1 and CB2 receptors or changes in intracellular calcium transient. Results of this novel study suggest that ODA exerts specific antiproliferative effects on RG2 glioblastoma cells through unconventional apoptotic mechanisms not involving canonical signals.

Pine rosin identified as a toxic cannabis extract adulterant

Pine rosin (colophony) has been identified as a potentially new adulterant in cannabis oil. Its inhalation toxicity poses a significant health concern to users. For example, pine rosin fumes are released during soldering, and have been cited as a causative agent of occupational asthma. Symptoms also include desquamation of bronchial epithelium, which has also been observed in e-cigarette or vaping product used-associated lung injury (EVALI) patients. The sample analyzed herein was acquired from a cannabis industry source, also contains medium chain triglycerides and oleamide, the latter of which is a hypnotic that is commonly found in the synthetic marijuana product Spice, or K2. A combination of proton nuclear magnetic resonance (¹H NMR) and high pressure liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESIMS) was used to unambiguously identify major pine rosin ingredients such as abietic and other resin acids. Comparison to commercial samples of pure pine rosin confirmed the assignment.

Effects of Oleamide on the Vasomotor Responses in the Rat

Introduction: Cardiovascular effects of endocannabinoids (eCBs) have generated considerable interest since it has been suggested that the eCB system could become the new pharmacological target, either by blocking its activity or by promoting its effects on several cardiovascular diseases such as hypovolemic and septic shock or hypertension. The purpose of this study was to examine the effects of oleamide on several vasomotor responses in adult rats. Materials and Methods: Blood pressure (BP) was measured both directly and indirectly. Coronary flow was quantified with Langendorf preparation, and the vasomotor responses induced by oleamide were analyzed in the aortic rings. Results: Oleamide induced a decrease in BP, by both direct and indirect methods, which were dose dependent. An increase in coronary flow was observed with Langendorf preparation depending on the dose. Oleamide produced a vasodilator response in aortic rings pre-contracted with phenylephrine (10^-5 M), which was concentration and endothelium dependent. This relaxing effect was of minor magnitude than that induced with the same dose on BP. L-NAME did not modify these effects. However, indomethacin induced a shift to the left of the concentration-response curve to oleamide and an increase in the magnitude of maximum vasodilation in rings with endothelium. Oleamide produced the maximal relaxant response at 10^-5 M concentration. Conclusions: Oleamide has both in vivo and in vitro vasodilator effects. Vasodilator effects could be mediated by compounds synthesized/released by the endothelium (hyperpolarizing factor) or acting directly on vascular smooth muscle in aortic rings. The TRPV1 and CB1R receptors could mediate these effects. Finally, the results suggest that oleamide probably induces the synthesis/release of a vasoconstrictor prostanoid.

Cannabinoids, Chemical Senses, and Regulation of Feeding Behavior

The herb Cannabis sativa has been traditionally used in many cultures and all over the world for thousands of years as medicine and recreation. However, because it was brought to the Western world in the late 19th century, its use has been a source of controversy with respect to its physiological effects as well as the generation of specific behaviors. In this regard, the CB1 receptor represents the most relevant target molecule of cannabinoid components on nervous system and whole-body energy homeostasis. Thus, the promotion of CB1 signaling can increase appetite and stimulate feeding, whereas blockade of CB1 suppresses hunger and induces hypophagia. Taste and flavor are sensory experiences involving the oral perception of food-derived chemicals and drive a primal sense of acceptable or unacceptable for what is sampled. Therefore, research within the last decades focused on deciphering the effect of cannabinoids on the chemical senses involved in food perception and consequently in the pattern of feeding. In this review, we summarize the data on the effect of cannabinoids on chemical senses and their influences on food intake control and feeding behavior.

Endocannabinoids and endocannabinoid-like compounds modulate hypoxia-induced permeability in CaCo-2 cells via CB1, TRPV1, and PPARα

BACKGROUND AND PURPOSE

We have previously reported that endocannabinoids modulate permeability in Caco-2 cells under inflammatory conditions and hypothesised in the present study that endocannabinoids could also modulate permeability in ischemia/reperfusion.

EXPERIMENTAL APPROACH

Caco-2 cells were grown on cell culture inserts to confluence. Trans-epithelial electrical resistance (TEER) was used to measure permeability. To generate hypoxia (0% O2), a GasPak™ EZ anaerobe pouch system was used. Endocannabinoids were applied to the apical or basolateral membrane in the presence or absence of receptor antagonists.

KEY RESULTS

Complete hypoxia decreased TEER (increased permeability) by ~35% after 4 h (recoverable) and ~50% after 6 h (non-recoverable). When applied either pre- or post-hypoxia, apical application of N-arachidonoyl-dopamine (NADA, via TRPV1), oleamide (OA, via TRPV1) and oleoylethanolamine (OEA, via TRPV1) inhibited the increase in permeability. Apical administration of anandamide (AEA) and 2-arachidonoylglycerol (2-AG) worsened the permeability effect of hypoxia (both via CB1). Basolateral application of NADA (via TRPV1), OA (via CB1 and TRPV1), noladin ether (NE, via PPARα), and palmitoylethanolamine (PEA, via PPARα) restored permeability after 4 h hypoxia, whereas OEA increased permeability (via PPARα). After 6 h hypoxia, where permeability does not recover, only basolateral application PEA sustainably decreased permeability, and NE decreased permeability.

CONCLUSIONS AND IMPLICATIONS

A variety of endocannabinoids and endocannabinoid-like compounds modulate Caco-2 permeability in hypoxia/reoxygenation, which involves multiple targets, depending on whether the compounds are applied to the basolateral or apical membrane. CB1 antagonism and TRPV1 or PPARα agonism may represent novel therapeutic targets against several intestinal disorders associated with increased permeability.

Identification of P2Y receptors involved in oleamide-suppressing inflammatory responses in murine microglia and human dendritic cells

Microglia, a type of immune cell in the central nervous system, are involved in inflammation leading to neurodegenerative diseases. We previously identified oleamide from fermented dairy products as a neuroprotective compound suppressing microglial inflammation. Oleamide is an endocannabinoid and displays anti-inflammatory activity via the cannabinoid-2 (CB2) receptor; however, the mechanism underlying this anti-inflammatory activity has not been fully elucidated. Here, we found that the suppressive effect of oleamide on microglial tumor necrosis factor-α (TNF-α) production was canceled by inhibitors of G-protein-coupled receptor (GPCR) downstream signaling but not by a CB2 antagonist, suggesting that GPCRs other than CB2 are involved in the anti-inflammatory effects of oleamide. An extensive screen for GPCRs using a transforming growth factor-α shedding assay system identified P2Y1, P2Y4, P2Y6, P2Y10, and P2Y11 as candidates for the oleamide target. P2Y1 and P2Y10 agonists suppressed microglial TNF-α production, while a pan P2 receptor antagonist canceled the suppressive effect. Furthermore, we observed a relationship between the P2Y1 agonistic activities and the suppressive activities of oleamide and its analogs. Taken together, our results suggest that, in addition to CB2, P2Y type receptors are the potential targets of oleamide, and P2Y1 plays a role in the suppression of microglial inflammatory responses by oleamide. (200/200 words)

Psychopharmacology of chronic pain

Chronic pain is a frequent condition that affects an estimated 20% of people worldwide, accounting for 15%-20% of doctors' appointments (Treede et al., 2015). It lacks the acute warning function of physiologic nociception, and instead involves the activation of multiple neurophysiologic mechanisms in the somatosensory system, a complex neuronal network under the control of powerful autoregulatory loops and able to undergo rapid neuroplastic alteration (Verdu et al., 2008). There is a growing body of research suggesting that some such pathways are shared by major psychologic disorders such as depression and anxiety, opening new avenues in co-treatment strategies. In particular, besides anticonvulsants, which are today used as analgesics, other psychopharmaceuticals, such as the tricyclic antidepressants, are displaying efficacy in the treatment of neuropathic and nociceptive chronic pain. The state of the art regarding the mechanisms of nociception and the pharmacology of both the neurotransmitters involved and the wide range of psychoactive compounds that may be useful in the treatment of chronic pain are discussed.

Cannabinoids in depressive disorders

Cannabis sativa is one of the most popular recreational and medicinal plants. Benefits from use of cannabinoid agents in epilepsy, multiple sclerosis, Parkinson's disease, Alzheimer's disease, and others have been suggested. It seems that the endocannabinoid system is also involved in the pathogenesis and treatment of depression, though its role in this mental disease has not been fully understood yet. Both the pro- and antidepressant activity have been reported after cannabis consumption and a number of pre-clinical studies have demonstrated that both agonist and antagonist of the endocannabinoid receptors act similarly to antidepressants. Responses to the cannabinoid agents are relatively fast, and most probably, the noradrenergic, serotoninergic, glutamatergic neurotransmission, neuroprotective activity, as well as modulation of the hypothalamic-pituitary-adrenal axis are implicated in the observed effects. Based on the published data, the endocannabinoid system evidently gives novel ideas and options in the field of antidepressant treatment, however further studies are needed to determine which group of patients could benefit from this type of therapy.

Maternal plasma metabolic fingerprint indicative for fetal Down syndrome

OBJECTIVE

The objective of the study was to perform maternal plasma metabolic fingerprinting to evaluate differences in plasma metabolites between healthy and Down syndrome (DS) pregnancies and to indicate novel non-invasive markers for DS prenatal diagnostics.

METHODS

This was a case-control study of pregnancies between 15th and 18th gestational week. LC-MS-based metabolic fingerprinting of plasma samples was performed.

RESULTS

Levels of five metabolites were significantly lower in the plasma of DS pregnancies. The majority of the statistically significant metabolites may be connected with fetal brain and central nervous system development (eg, fatty acid amides). According to the receiver operating characteristic (ROC), the combination of linoleamide and piperine has the highest diagnostic potential: area under the curve (AUC) = 0.878, sensitivity of 100%, and specificity of 73.3%.

CONCLUSIONS

The study indicates disturbances in maternal metabolic pathways evoked by fetal DS. Novel potential maternal plasma metabolomic markers for non-invasive prenatal diagnostics of fetal DS are proposed.

2-Arachidonoylglycerol: A signaling lipid with manifold actions in the brain

2-Arachidonoylglycerol (2-AG) is a signaling lipid in the central nervous system that is a key regulator of neurotransmitter release. 2-AG is an endocannabinoid that activates the cannabinoid CB₁ receptor. It is involved in a wide array of (patho)physiological functions, such as emotion, cognition, energy balance, pain sensation and neuroinflammation. In this review, we describe the biosynthetic and metabolic pathways of 2-AG and how chemical and genetic perturbation of these pathways has led to insight in the biological role of this signaling lipid. Finally, we discuss the potential therapeutic benefits of modulating 2-AG levels in the brain.

Effect of Endocannabinoid Oleamide on Rat and Human Liver Cytochrome P450 Enzymes in In Vitro and In Vivo Models

The endocannabinoid system is important for many physiologic and pathologic processes, but its role in the regulation of liver cytochromes P450 (P450s) remains unknown. We studied the influence of the endocannabinoid oleamide on rat and human liver P450s. Oleamide was administered intraperitoneally to rats at doses of 0.1, 1, and 10 mg/kg per day for 7 days. The content and activity of key P450s were evaluated in rat liver microsomes. Moreover, interactions with nuclear receptors regulating P450 genes and serum levels of their ligands (prolactin, corticosterone, and free triiodothyronine) were tested in in vitro P450 inhibition assays. Decreased protein levels and metabolic activities of CYP1A2, CYP2B, and CYP2C11, along with a drop in metabolic activity of CYP2D2, were observed in animals treated with oleamide (10 mg/kg per day). The activities of CYP2C6, CYP2A, and CYP3A and the levels of hormones were not altered. In vitro, oleamide exhibited a weak inhibition of rat CYP1A2, CYP2D2, and CYP2C6. The activities of rat CYP2A, CYP2B, CYP2C11, and CYP3A and human CYP1A2, CYP2B6, CYP2C9, and CYP3A4 were not altered. Oleamide did not interact with human pregnane X, constitutive androstane, or aryl hydrocarbon receptors in reporter gene experiments and did not regulate their target P450 genes in primary human hepatocytes. Our results indicate that oleamide caused the downregulation of some rat liver P450s, and hormones are not mediators of this effect. In vitro oleamide inhibits mainly rat CYP2C6 and is neither an agonist nor antagonist of major human nuclear receptors involved in the regulation of xenobiotic metabolism.

Do Cannabinoids Confer Neuroprotection Against Epilepsy? An Overview

Objective:

Cannabinoid-based medications provide not only relief for specific symptoms, but also arrest or delay of disease progression in patients with pain, multiple sclerosis, and other conditions. Although they also seem to hold potential as anticonvulsant agents, evidence of their efficacy in epilepsy is supported by several evidences.

Method:

The data reviewed herein lend support to the notion that the endocannabinoid signalling system plays a key modulation role in the activities subserved by the hippocampus, which is directly or indirectly affected in epilepsy patients.

Conclusion:

The notion is supported by a variety of anatomical, electrophysiological, biochemical and pharmacological findings. These data suggest the need for developing novel treatments using compounds that selectively target individual elements of the endocannabinoid signalling system.

The Chemistry and Pharmacology of Synthetic Cannabinoid Receptor Agonists as New Psychoactive Substances: Origins

Synthetic cannabinoid receptor agonists (SCRAs) have proliferated as new psychoactive substances (NPS) over the past decade. Relative to other classes of NPS, SCRAs are structurally heterogeneous; however, most SCRAs act as potent, high-efficacy agonists of cannabinoid type 1 and type 2 receptors (CB₁ and CB₂, respectively). Characterization of the pharmacology and toxicology of these substances is hindered by the dynamic nature of the SCRA marketplace. Beyond basic pharmacological profiling at CB₁ and CB₂ receptors, very little is known about the acute or chronic effects of SCRAs. Many of the effects of SCRAs are qualitatively similar to those of the Δ⁹-tetrahydrocannabinol (Δ⁹-THC) found in cannabis. However, unlike Δ⁹-THC, SCRAs are frequently associated with serious adverse effects, including cardiotoxicity, nephrotoxicity, and death. This chapter will provide an overview of the structure and function of the primary target for SCRAs, the CB₁ receptor, and survey the structure-activity relationships of the historical SCRAs that served as templates for the earliest generations of NPS.

Antiepileptic and Neuroprotective Effects of Oleamide in Rat Striatum on Kainate-Induced Behavioral Seizure and Excitotoxic Damage via Calpain Inhibition

Oleamide was first known as a sleep-inducing fatty acid amide, and later shown to have wide range of neuropharmacological effects upon different neurochemical systems. However, the effects of oleamide on brain damage have scarcely been studied, and the molecular mechanisms and sites of its action remain elusive. Kainic acid (KA) has been used to produce an epileptic animal model that mimics human temporal lobe epilepsy and to induce calpain-activated excitotoxicity, which occurs in numerous neurodegenerative disorders. In this study, we examined whether oleamide protects against the KA-induced excitotoxic brain damage accompanied by behavioral seizure activity and neuronal cell death. Moreover, whether these effects of oleamide were mediated by calpain activity-related cellular mechanisms was investigated. KA-induced epileptic rats were produced by an intrastriatal injection of KA (5 nmole). Oral administration of oleamide (0.5, 2, and 10 mg/kg) 30 min prior to the KA injection showed dose-dependent inhibition of the KA-induced behavioral seizure activities that were monitored starting from 60 to 180 min post-surgery. Further repetitive oral administration of oleamide (once per day) for the next 4 consecutive days post-KA injection produced significant neuroprotection against the disrupted neuronal integrity that resulted from KA-induced excitotoxic damage that was also demonstrated by staining of striatal tissue sections with cresyl violet, hematoxylin/eosin, and fluoro-Jade B. In addition, oleamide blocked the KA-induced cleavage of cyclin-dependent kinase-5 coactivator (Cdk5-p35) and collapsin response mediator protein-2, which are believed to be mediated by calpain activation in striatal tissues dissected from KA-induced epileptic rats. Oleamide also reversed the KA-induced reduction in expression of an endogenous calpain inhibitory protein, calpastatin, and a marker of synaptic activity, synapsin-II. The hypothesis that oleamide could induce direct calpain inhibition was further investigated using in vitro calpain assays in both brain tissue and a cell-free and calpain-overexpressed neuronal cell system. These findings together suggest that oleamide has protective effects against excitotoxicity-induced neuronal death and behavioral seizure, partly via its direct calpain inhibitory activity.

UHPLC-Q-TOF-MS based serum metabonomics revealed the metabolic perturbations of ischemic stroke and the protective effect of RKIP in rat models

Stroke is one of the most fatal diseases in the world, which is seriously threatening human life. Raf kinase inhibitory protein (RKIP) is involved in the regulation of several signaling pathways and is important for cell growth, proliferation, differentiation and apoptosis. In the present study, the protective effect of RKIP on stroke was investigated by the metabonomics method based on the UHPLC-Q-TOF-MS technique. TTC staining of brain tissues showed that RKIP overexpression by the lentivirus markedly reduced the necrotic area after ischemic stroke. Subsequent metabolomic profiling revealed that the protective effect of RKIP overexpression on ischemic stroke is mainly reflected in the metabolism of energy, amino acids and lipids. Several metabolites involved in purine, pyrimidine and fatty acid metabolism were identified. It was also shown that the protective effect of RKIP on ischemic stroke might be mediated by inhibiting the inflammatory response. The current study provided insight into the molecular mechanism of ischemic stroke and a reliable basis for the development of novel therapeutic targets for the treatment of ischemic stroke.

The CB2 receptor and its role as a regulator of inflammation

The CB2 receptor is the peripheral receptor for cannabinoids. It is mainly expressed in immune tissues, highlighting the possibility that the endocannabinoid system has an immunomodulatory role. In this respect, the CB2 receptor was shown to modulate immune cell functions, both in cellulo and in animal models of inflammatory diseases. In this regard, numerous studies have reported that mice lacking the CB2 receptor have an exacerbated inflammatory phenotype. This suggests that therapeutic strategies aiming at modulating CB2 signaling could be promising for the treatment of various inflammatory conditions. Herein, we review the pharmacology of the CB2 receptor, its expression pattern, and the signaling pathways induced by its activation. We next examine the regulation of immune cell functions by the CB2 receptor and the evidence obtained from primary human cells, immortalized cell lines, and animal models of inflammation. Finally, we discuss the possible therapies targeting the CB2 receptor and the questions that remain to be addressed to determine whether this receptor could be a potential target to treat inflammatory disease.

Inhibitory action of linoleamide and oleamide toward sarco/endoplasmic reticulum Ca2+-ATPase

BACKGROUND

SERCA maintains intracellular Ca²⁺ homeostasis by sequestering cytosolic Ca²⁺ into SR/ER stores. Two primary fatty acid amides (PFAAs), oleamide (18:1^9-cis) and linoleamide (18:2^9,12-cis), induce an increase in intracellular Ca²⁺ levels, which might be caused by their inhibition of SERCA.

METHODS

Three major SERCA isoforms, rSERCA1a, hSERCA2b, and hSERCA3a, were individually overexpressed in COS-1 cells, and the inhibitory action of PFAAs on Ca²⁺-ATPase activity of SERCA was examined.

RESULTS

The Ca²⁺-ATPase activity of each SERCA was inhibited in a concentration-dependent manner strongly by linoleamide (IC₅₀ 15-53μM) and partially by oleamide (IC₅₀ 8.3-34μM). Inhibition by other PFAAs, such as stearamide (18:0) and elaidamide (18:1^9-trans), was hardly or slightly observed. With increasing dose, linoleamide decreased the apparent affinity for Ca²⁺ and the apparent maximum velocity of Ca²⁺-ATPase activity of all SERCAs tested. Oleamide also lowered these values for hSERCA3a. Meanwhile, oleamide uniquely reduced the apparent Ca²⁺ affinity of rSERCA1a and hSERCA2b: the reduction was considerably attenuated above certain concentrations of oleamide. The dissociation constants for SERCA interaction varied from 6 to 45μM in linoleamide and from 1.6 to 55μM in oleamide depending on the isoform.

CONCLUSIONS

Linoleamide and oleamide inhibit SERCA activity in the micromolar concentration range, and in a different manner. Both amides mainly suppress SERCA activity by lowering the Ca²⁺ affinity of the enzyme.

GENERAL SIGNIFICANCE

Our findings imply a novel role of these PFAAs as modulators of intracellular Ca²⁺ homeostasis via regulation of SERCA activity.

Endocannabinoid system: Role in depression, reward and pain control (Review)

Depression and pain co-exist in almost 80% of patients and are associated with impaired health-related quality of life, often contributing to high mortality. However, the majority of patients who suffer from the comorbid depression and pain are not responsive to pharmacological treatments that address either pain or depression, making this comorbidity disorder a heavy burden on patients and society. In ancient times, this depression-pain comorbidity was treated using extracts of the Cannabis sativa plant, known now as marijuana and the mode of action of Δ9‑tetrahydrocannabinol, the active cannabinoid ingredient of marijuana, has only recently become known, with the identification of cannabinoid receptor type 1 (CB1) and CB2. Subsequent investigations led to the identification of endocannabinoids, anandamide and 2-arachidonoylglycerol, which exert cannabinomimetic effects through the CB1 and CB2 receptors, which are located on presynaptic membranes in the central nervous system and in peripheral tissues, respectively. These endocannabinoids are produced from membrane lipids and are lipohilic molecules that are synthesized on demand and are eliminated rapidly after their usage by hydrolyzing enzymes. Clinical studies revealed altered endocannabinoid signaling in patients with chronic pain. Considerable evidence suggested the involvement of the endocannabinoid system in eliciting potent effects on neurotransmission, neuroendocrine, and inflammatory processes, which are known to be deranged in depression and chronic pain. Several synthetic cannabinomimetic drugs are being developed to treat pain and depression. However, the precise mode of action of endocannabinoids on different targets in the body and whether their effects on pain and depression follow the same or different pathways, remains to be determined.

Passiflora incarnata attenuation of neuropathic allodynia and vulvodynia apropos GABA-ergic and opioidergic antinociceptive and behavioural mechanisms

Background

Passiflora incarnata is widely used as an anxiolytic and sedative due to its putative GABAergic properties. Passiflora incarnata L. methanolic extract (PI-ME) was evaluated in an animal model of streptozotocin-induced diabetic neuropathic allodynia and vulvodynia in rats along with antinociceptive, anxiolytic and sedative activities in mice in order to examine possible underlying mechanisms.

Methods

PI-ME was tested preliminary for qualitative phytochemical analysis and then quantitatively by proximate and GC-MS analysis. The antinociceptive property was evaluated using the abdominal constriction assay and hot plate test. The anxiolytic activity was performed in a stair case model and sedative activity in an open field test. The antagonistic activities were evaluated using naloxone and/or pentylenetetrazole (PTZ). PI-ME was evaluated for prospective anti-allodynic and anti-vulvodynic properties in a rat model of streptozotocin induced neuropathic pain using the static and dynamic testing paradigms of mechanical allodynia and vulvodynia.

Results

GC-MS analysis revealed that PI-ME contained predominant quantities of oleamide (9-octadecenamide), palmitic acid (hexadecanoic acid) and 3-hydroxy-dodecanoic acid, among other active constituents. In the abdominal constriction assay and hot plate test, PI-ME produced dose dependant, naloxone and pentylenetetrazole reversible antinociception suggesting an involvement of opioidergic and GABAergic mechanisms. In the stair case test, PI-ME at 200 mg/kg increased the number of steps climbed while at 600 mg/kg a significant decrease was observed. The rearing incidence was diminished by PI-ME at all tested doses and in the open field test, PI-ME decreased locomotor activity to an extent that was analagous to diazepam. The effects of PI-ME were antagonized by PTZ in both the staircase and open field tests implicating GABAergic mechanisms in its anxiolytic and sedative activities. In the streptozotocin-induced neuropathic nociceptive model, PI-ME (200 and 300 mg/kg) exhibited static and dynamic anti-allodynic effects exemplified by an increase in paw withdrawal threshold and paw withdrawal latency. PI-ME relieved only the dynamic component of vulvodynia by increasing flinching response latency.

Conclusions

These findings suggest that Passiflora incarnata might be useful for treating neuropathic pain. The antinociceptive and behavioural findings inferring that its activity may stem from underlying opioidergic and GABAergic mechanisms though a potential oleamide-sourced cannabimimetic involvement is also discussed.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-016-1048-6) contains supplementary material, which is available to authorized users.

For whom the endocannabinoid tolls: Modulation of innate immune function and implications for psychiatric disorders

Toll-like receptors (TLRs) mediate the innate immune response to pathogens and are critical in the host defence, homeostasis and response to injury. However, uncontrolled and aberrant TLR activation can elicit potent effects on neurotransmission and neurodegenerative cascades and has been proposed to trigger the onset of certain neurodegenerative disorders and elicit detrimental effects on the progression and outcome of established disease. Over the past decade, there has been increasing evidence demonstrating that the endocannabinoid system can elicit potent modulatory effects on inflammatory processes, with clinical and preclinical evidence demonstrating beneficial effects on disease severity and symptoms in several inflammatory conditions. This review examines the evidence supporting a modulatory effect of endocannabinoids on TLR-mediated immune responses both peripherally and centrally, and the implications for psychiatric disorders such as depression and schizophrenia.

Prospects for Creation of Cardioprotective Drugs Based on Cannabinoid Receptor Agonists

Cannabinoids can mimic the infarct-reducing effect of early ischemic preconditioning, delayed ischemic preconditioning, and ischemic postconditioning against myocardial ischemia/reperfusion. They do this primarily through both CB1 and CB2 receptors. Cannabinoids are also involved in remote preconditioning of the heart. The cannabinoid receptor ligands also exhibit an antiapoptotic effect during ischemia/reperfusion of the heart. The acute cardioprotective effect of cannabinoids is mediated by activation of protein kinase C, extracellular signal-regulated kinase, and p38 kinase. The delayed cardioprotective effect of cannabinoid anandamide is mediated via stimulation of phosphatidylinositol-3-kinase-Akt signaling pathway and enhancement of heat shock protein 72 expression. The delayed cardioprotective effect of another cannabinoid, Δ9-tetrahydrocannabinol, is associated with augmentation of nitric oxide (NO) synthase expression, but data on the involvement of NO synthase in the acute cardioprotective effect of cannabinoids are contradictory. The adenosine triphosphate-sensitive K+ channel is involved in the synthetic cannabinoid HU-210-induced cardiac resistance to ischemia/reperfusion injury. Cannabinoids inhibit Na+/Ca2+ exchange via peripheral cannabinoid receptor (CB2) activation that may also be related to the antiapoptotic and cardioprotective effects of cannabinoids. The cannabinoid receptor agonists should be considered as prospective group of compounds for creation of drugs that are able to protect the heart against ischemia–reperfusion injury in the clinical setting.

The Endocannabinoid System and its Modulation by Phytocannabinoids

The endocannabinoid system is currently defined as the ensemble of the two 7-transmembrane-domain and G protein-coupled receptors for Δ(9)-tetrahydrocannabinol (but not for most other plant cannabinoids or phytocannabinoids)-cannabinoid receptor type-1 (CB1R) and cannabinoid receptor type-2 (CB2R); their two most studied endogenous ligands, the "endocannabinoids" N-arachidonoylethanolamine (anandamide) and 2-arachidonoylglycerol (2-AG); and the enzymes responsible for endocannabinoid metabolism. However, anandamide and 2-AG, and also the phytocannabinoids, have more molecular targets than just CB1R and CB2R. Furthermore, the endocannabinoids, like most other lipid mediators, have more than just one set of biosynthetic and degrading pathways and enzymes, which they often share with "endocannabinoid-like" mediators that may or may not interact with the same proteins as Δ(9)-tetrahydrocannabinol and other phytocannabinoids. In some cases, these degrading pathways and enzymes lead to molecules that are not inactive and instead interact with other receptors. Finally, some of the metabolic enzymes may also participate in the chemical modification of molecules that have very little to do with endocannabinoid and cannabinoid targets. Here, we review the whole world of ligands, receptors, and enzymes, a true "endocannabinoidome", discovered after the cloning of CB1R and CB2R and the identification of anandamide and 2-AG, and its interactions with phytocannabinoids.

Assessment of population genetic structure in the arbovirus vector midge, Culicoides brevitarsis (Diptera: Ceratopogonidae), using multi-locus DNA microsatellites

Bluetongue virus (BTV) is a major pathogen of ruminants that is transmitted by biting midges (Culicoides spp.). Australian BTV serotypes have origins in Asia and are distributed across the continent into two distinct episystems, one in the north and another in the east. Culicoides brevitarsis is the major vector of BTV in Australia and is distributed across the entire geographic range of the virus. Here, we describe the isolation and use of DNA microsatellites and gauge their ability to determine population genetic connectivity of C. brevitarsis within Australia and with countries to the north. Eleven DNA microsatellite markers were isolated using a novel genomic enrichment method and identified as useful for genetic analyses of sampled populations in Australia, northern Papua New Guinea (PNG) and Timor-Leste. Significant (P < 0.05) population genetic subdivision was observed between all paired regions, though the highest levels of genetic sub-division involved pair-wise tests with PNG (PNG vs. Australia (FST = 0.120) and PNG vs. Timor-Leste (FST = 0.095)). Analysis of multi-locus allelic distributions using STRUCTURE identified a most probable two-cluster population model, which separated PNG specimens from a cluster containing specimens from Timor-Leste and Australia. The source of incursions of this species in Australia is more likely to be Timor-Leste than PNG. Future incursions of BTV positive C. brevitarsis into Australia may be genetically identified to their source populations using these microsatellite loci. The vector's panmictic genetic structure within Australia cannot explain the differential geographic distribution of BTV serotypes.

Cannabinoid Ligands and Alcohol Addiction: A Promising Therapeutic Tool or a Humbug?

The vast therapeutic potential of cannabinoids of both synthetic and plant-derived origins currently makes these compounds the focus of a growing interest. Although cannabinoids are still illicit drugs, their possible clinical usefulness, including treatment of acute or neuropathic pain, have been suggested by several studies. In addition, some observations indicate that cannabinoid receptor antagonists may be useful for the treatment of alcohol dependence and addiction, which is a major health concern worldwide. While the synergism between alcohol and cannabinoid agonists (in various forms) creates undesirable side effects when the two are consumed together, the administration of CB1 antagonists leads to a significant reduction in alcohol consumption. Furthermore, cannabinoid antagonists also mitigate alcohol withdrawal symptoms. Herein, we present an overview of studies focusing on the effects of cannabinoid ligands (agonists and antagonists) during acute or chronic consumption of ethanol.

High Times for Painful Blues: The Endocannabinoid System in Pain-Depression Comorbidity

Depression and pain are two of the most debilitating disorders worldwide and have an estimated cooccurrence of up to 80%. Comorbidity of these disorders is more difficult to treat, associated with significant disability and impaired health-related quality of life than either condition alone, resulting in enormous social and economic cost. Several neural substrates have been identified as potential mediators in the association between depression and pain, including neuroanatomical reorganization, monoamine and neurotrophin depletion, dysregulation of the hypothalamo-pituitary-adrenal axis, and neuroinflammation. However, the past decade has seen mounting evidence supporting a role for the endogenous cannabinoid (endocannabinoid) system in affective and nociceptive processing, and thus, alterations in this system may play a key role in reciprocal interactions between depression and pain. This review will provide an overview of the preclinical evidence supporting an interaction between depression and pain and the evidence supporting a role for the endocannabinoid system in this interaction.