Isolation and structure of a brain constituent that binds to the cannabinoid receptor

Immunotoxicological disruption of pregnancy as a new research area in immunotoxicology

Immune mechanisms associated with normal pregnancy have only been being substantively investigated since the early 1990s. In parallel with the progress in that area of research, in the past few years it has become increasingly clear that several xenobiotics - including a variety of environmental chemicals, pharmaceuticals, and metals are considered to be both generally immunotoxic and specifically able to affect pregnancy. Among these, there is intense interest regarding potential effects from synthetic cannabinoids, immune checkpoint inhibitors, nanometals, and microplastics, with immunotoxic events that impact on pregnancy being shown for these agents. For instance, phytocannabinoids have been shown to interfere with reproduction in mice through effects on the endocannabinoid system. Because of effects of immune enhancement, as a requirement for regulatory submission, co-inhibitory immune checkpoint molecule inhibitors were also evaluated for effects on pregnancy. Similarly, because of increasing use and concerns about incidental environmental exposures, nanometals, and micro-plastics have also been examined for effects. Several studies in humans or mice showed that exposures to each during gestation increased the risk/rate of fetal loss, in part, by disruption of the placenta-associated immune system. Furthermore, signaling by endogenous danger molecules and/or impairment of physiological intercellular mediators may have contributed to the pregnancy loss. As there are clearly a variety of immunotoxic effects that can impact on a pregnancy, this review attempts to briefly introduce immune mechanisms associated with pregnancy as well as reasons for its loss, and proposes that 'immunotoxicological disruption of pregnancy' be accepted as a new research area in immunotoxicology.

The endocannabinoid and paracannabinoid systems in natural reward processes: possible pharmacological targets?

Natural rewards such as food, mating, and social interaction are essential for survival and species preservation, and their regulation involves a complex interplay of motivational, cognitive, and emotional processes. Over the past two decades, increasing attention has been directed toward the endocannabinoid system and its paracannabinoid counterpart as key modulators of these behaviors. This review aims to provide an integrated overview of the roles played by the endocannabinoid and paracannabinoid systems in regulating natural reward-driven behaviors, focusing on feeding, reproductive behavior, and social interaction. We highlight how the endocannabinoid system - mainly through CB1 receptor signaling - modulates central and peripheral circuits involved in energy homeostasis, reward processing, and emotional regulation. In parallel, we explore the role of paracannabinoids, such as oleoylethanolamide (OEA), palmitoylethanolamide (PEA), and stearoylethanolamide (SEA), which act primarily via non-cannabinoid receptors and contribute to the regulation of appetite, sexual motivation, and social behavior. Special attention is given to the relevance of these systems in the pathophysiology of obesity, eating disorders, sexual dysfunctions, and social impairments, as well as their potential as pharmacological targets. Overall, the evidence discussed supports a broader conceptualization of endocannabinoid and paracannabinoid signaling as pivotal regulators of natural rewards and opens new avenues for the development of targeted interventions for motivational and reward-related disorders.

Role of endocannabinoid neurotransmission in the insular cortex on cardiovascular, autonomic and behavioral responses evoked by acute restraint stress in rats

This study aimed to investigate the role of endocannabinoid mechanisms present within the insular cortex (IC) on cardiovascular, autonomic and anxiogenic-like responses evoked by an acute session of restraint in rats. For this, bilateral guide cannulas directed to the IC were implanted in male Wistar rats for intrabrain microinjection of the selective CB1 receptor antagonist AM251, the selective TRPV1 receptor antagonist capsazepine, the fatty acid amide hydrolase (FAAH) inhibitor URB597 or the monoacylglycerol lipase (MAGL) inhibitor JZL184. The effects of pharmacological treatments were evaluated on restraint-evoked increases in blood pressure and heart rate, sympathetically-mediated cutaneous vasoconstriction and in delayed anxiogenic-like effect assessed 24h after stress exposure in the elevated plus maze (EPM) and open field (OF). We observed that acute restraint stress decreased the exploration of both EPM open arms and OF center region in animals treated with vehicle into the IC, thus indicating an anxiogenic-like effect. Inhibition of MAGL within the IC evoked by local treatment with JZL184 avoided the restraint-evoked anxiogenic effect. IC treatment with JZL184 also attenuated the tachycardia during restraint. The other pharmacological treatments did not modify the cardiovascular, autonomic and behavioral responses evoked by restraint. Taken together, these findings suggest that endocannabinoid neurotransmission in the IC, potentially acting through the endocannabinoid 2-arachidonoylglycerol, plays an inhibitory role in both tachycardia and anxiogenic-like effect evoked by stressful events.

Exploring the diversity of cannabis cannabinoid and non-cannabinoid compounds and their roles in Alzheimer's disease: A review

Cannabis sativa is recognized for its chemical diversity and therapeutic potential, particularly in addressing neurodegenerative diseases such as Alzheimer's disease (AD). Given the complexity of AD, where single-target therapies often prove inadequate, a multi-target approach utilizing cannabis-derived compounds may offer promising alternatives. This review first highlights the chemical diversity of cannabis by categorizing its compounds into cannabinoids and non-cannabinoids. It then examines studies investigating the effects of these compounds on AD-related pathological features. By synthesizing existing knowledge, identifying research gaps, and facilitating comparative analysis, this review aims to advance future research and understanding. It underscores cannabis's potential as a multi-target therapeutic strategy for AD, contributing valuable insights to ongoing scientific discussions.

Advances in cannabinoid receptors pharmacology: from receptor structural insights to ligand discovery

The medicinal and recreational uses of Cannabis sativa have been recognized for thousands of years. Today, cannabis-derived medicines are used to treat a variety of conditions, including chronic pain, epilepsy, multiple sclerosis, and chemotherapy-induced nausea. However, cannabis use disorder (CUD) has become the third most prevalent substance use disorder globally. Cannabinoid receptors are the primary targets that mediate the effects of cannabis and its analogs. Despite their importance, the mechanisms of modulation and the full therapeutic potential of cannabinoid receptors remain unclear, hindering the development of the next generation of cannabinoid-based drugs. This review summarizes the discovery and medicinal potential of phytocannabinoids and explores the distribution, signaling pathways, and functional roles of cannabinoid receptors. It also discusses classical cannabinoid drugs, as well as agonists, antagonists, and inverse agonists, which serve as key therapeutic agents. Recent advancements in the development of allosteric drugs are highlighted, with a focus on positive and negative allosteric modulators (PAMs and NAMs) that target CB1 and CB2 receptors. The identification of multiple allosteric sites on the CB1 receptor and the structural basis for allosteric modulation are emphasized, along with the structure-based discovery of ago-BAMs for CB1. This review concludes by examining the future potential of allosteric modulators in cannabinoid drug development, noting that ongoing progress in cannabinoid-derived drugs continues to open new avenues for therapeutic use and paves the way for future research into their full medicinal potential.

No Evidence for Endocannabinoid-Induced G Protein Subtype Selectivity at Human and Rodent Cannabinoid CB1 Receptors

Introduction: The endocannabinoid system (ECS) is a widespread neurotransmitter system. A key characteristic of the ECS is that there are multiple endogenous ligands (endocannabinoids). Of these, the most extensively studied are arachidonoyl ethanolamide (AEA) and 2-arachidonoyl-glycerol (2-AG), both act as agonists at the cannabinoid CB1 receptor. In humans, three CB1 variants have been identified: hCB1, considered the most abundant G protein-coupled receptor in the brain, alongside the less abundant and studied variants, hCB1a and hCB1b. CB1 exhibits a preference for coupling with inhibitory Gi/o proteins, although its interactions with specific members of the Gi/o family remain poorly characterized. This study aimed to compare the AEA and 2-AG-induced activation of various G protein subtypes at CB1. Furthermore, we compared the response of human CB1 (hCB1, hCB1a, hCB1b) and explored species differences by examining rodent receptors (mCB1, rCB1). Materials and Methods: Activation of individual G protein subtypes in HEK293 cells transiently expressing CB1 was measured with G protein dissociation assay utilizing TRUPATH biosensors. The performance of the TRUPATH biosensors was evaluated using Z-factor analysis. Pathway potencies and efficacies were analyzed using the operational analysis of bias to determine G protein subtype selectivity for AEA and 2-AG. Results: Initial screening of TRUPATH biosensors performance revealed variable sensitivities within our system. Based on the biosensor performance, the G protein subtypes pursued for further characterization were Gi1, Gi3, GoA, GoB, GZ, G12, and G13. Across all pathways, AEA demonstrated partial agonism, whereas 2-AG exhibited full or high-efficacy agonism. Notably, we provide direct evidence that the hCB1 receptor couples to G12 and G13 proteins. Our findings do not indicate any evidence of G protein subtype selectivity. Similar observations were made across the human receptor variants (hCB1, hCB1a, hCB1b), as well as at mCB1 and rCB1. Discussion: There was no evidence suggesting G protein subtype selectivity for AEA and 2-AG at CB1, and this finding remained consistent across human receptor variants and different species.

The efficacy of elevating anandamide via inhibition of fatty acid amide hydrolase (FAAH) combined with internet-delivered cognitive behavioral therapy in the treatment of post-traumatic stress disorder: a randomized, placebo-controlled clinical trial

Post-traumatic stress disorder (PTSD) is a severe mental health disorder with limited treatment options. Gold standard treatment includes cognitive behavioral therapies (CBT) that incorporate exposure to traumatic memories to facilitate extinction. CBT can be effective in PTSD, but effects are incomplete and symptoms are prone to spontaneous return. Pharmacologically facilitating fear extinction could potentiate the effects of exposure-based therapy. Here, we explored whether targeting the endocannabinoid (eCB) system, a neuromodulatory system critically involved in fear extinction, would promote the efficacy of exposure-based CBT. Specifically, we tested the effects of elevating the eCB ligand anandamide (AEA) via inhibition of its main degradative enzyme, fatty acid amide hydrolase (FAAH). In this double-blind, placebo-controlled study, patients with PTSD (N = 100; 85 women) were randomized to the FAAH inhibitor (FAAHi) JNJ-42165279 (25 mg b.i.d.) or placebo for 12 weeks. In weeks 5-12, all participants completed an internet-delivered CBT that included exposure-based modules. The primary outcome was clinician-assessed PTSD symptom severity (CAPS-5). Secondary outcomes included self-reported symptoms of PTSD, depression, anxiety, and sleep quality. Blood samples were taken to measure levels of drug and eCBs. Overall, PTSD symptoms improved over time. While FAAHi increased AEA levels, there was no effect of FAAHi on PTSD symptoms or any secondary measure. FAAHi combined with internet-delivered CBT did not improve PTSD symptoms to a greater extent than internet-delivered CBT alone. Thus, FAAH inhibition does not appear to be a suitable adjunct treatment for enhancing CBT in PTSD. This study was registered as Eudra-CT 2020-001965-36.

GzESTY as an optimized cell-based assay for initial steps in GPCR deorphanization

G protein-coupled receptors (GPCRs) are key pharmacological targets, yet many remain underutilized due to unknown activation mechanisms and ligands. Orphan GPCRs, lacking identified natural ligands, are a high priority for research, as identifying their ligands will aid in understanding their functions and potential as drug targets. Most GPCRs, including orphans, couple to Gi/o/z family members, however current assays to detect their activation are limited, hindering ligand identification efforts. We introduce GzESTY, a sensitive, cell-based assay developed in an easily deliverable format designed to study the pharmacology of Gi/o/z-coupled GPCRs and assist in deorphanization. We optimized assay conditions and developed an all-in-one vector employing cloning methods to ensure the correct expression ratio of GzESTY components. GzESTY successfully assessed activation of a library of ligand-activated GPCRs, detecting both full and partial agonism, and responses from endogenous GPCRs. Notably, with GzESTY we established the presence of endogenous ligands for GPR176 and GPR37 in brain extracts, validating its use in deorphanization efforts. This assay enhances the ability to find ligands for orphan GPCRs, expanding the toolkit for GPCR pharmacologists.

Acetaminophen inhibits diacylglycerol lipase synthesis of 2-arachidonoyl glycerol: Implications for nociception

Acetaminophen (paracetamol) is a common analgesic, but its mechanism of action remains unknown. Despite causing around 500 deaths annually in the US, safer alternatives have not been developed. Because endocannabinoids may have a role in acetaminophen action, we examine interactions between the two. We report that acetaminophen inhibits the activity of diacylglycerol lipase α (DAGLα), but not DAGLβ, decreasing the production of the endocannabinoid 2-arachidonoyl glycerol. This gives rise to the counterintuitive hypothesis that decreasing endocannabinoid production by DAGLα inhibition may be antinociceptive in certain settings. Supporting this hypothesis, we find that diacylglycerol lipase (DAGL) inhibition by RHC80267 is antinociceptive in wild-type but not CB1 knockout mice in the hot-plate test. We propose (1) that activation of DAGLα may exacerbate some forms of nociception and (2) a mechanism for the antinociceptive actions of acetaminophen, whereby acetaminophen inhibits a DAGLα/CB1-based circuit that plays a permissive role in at least one form of nociception.

Beyond the hype: a comprehensive exploration of CBD's biological impacts and mechanisms of action

BACKGROUND

Cannabidiol (CBD) is the primary non-psychoactive component of cannabis. Consumption of CBD is increasing rapidly as it is federally legal and widely available in the United States, Europe, Mexico, Canada, and Asia. CBD is gaining traction in medical and biochemical research, though a comprehensive classification of CBD receptor interactions is yet to be elucidated.

METHODS

A comprehensive literature search across PubMed, Web of Science, and Google Scholar identified studies reporting cannabidiol (CBD) interactions with receptors, enzymes, and biological processes. Eligible articles included cell culture, animal model, biochemical, and clinical studies. Findings were thematically synthesized by body system, emphasizing mechanisms and implications for health and disease.

RESULTS

Herein, I compile the literature to date of known interactions between CBD and various receptors, enzymes, and processes. I discuss the impact of CBD exposure on multiple processes, including endocannabinoid receptors, ion channels, cytochrome 450 enzymes, inflammatory pathways, and sex hormone regulation. I explain the potential effects of CBD on psychiatric disorders, seizure activity, nausea and vomiting, pain sensation, thermal regulation, neuronal signaling, neurodegenerative diseases, reproductive aging, drug metabolism, inflammation, sex hormone regulation, and energy homeostasis.

CONCLUSIONS

Understanding how CBD functions and how it can interact with other recreational or pharmaceutical medications is necessary for proper clinical management of patients who consume CBD.

Enhanced Cytotoxicity and Receptor Modulation by SMA-WIN 55,212-2 Micelles in Glioblastoma Cells

Glioblastoma (GBM), a devastating brain malignancy, resists conventional therapies due to molecular heterogeneity and the blood-brain barrier's significant restriction on drug delivery. Cannabinoids like WIN 55,212-2 show promise but are limited by poor solubility and systemic toxicity. To address these challenges, we evaluated styrene-maleic acid (SMA) micellar encapsulation of WIN 55,212-2 (SMA-WIN) against free WIN in epithelial (LN18) and mesenchymal (A172) GBM cell lines, targeting cytotoxicity and receptor modulation (CB1, CB2, TRPV1, PPAR-γ). SMA-WIN exhibited significantly enhanced cytotoxicity, achieving IC50 values of 12.48 µM (LN18) and 16.72 µM (A172) compared to 20.97 µM and 30.9 µM for free WIN, suggesting improved cellular uptake via micellar delivery. In LN18 cells, both formulations upregulated CB1 and CB2, promoting apoptosis. Notably, SMA-WIN uniquely increased PPAR-γ expression by 2.3-fold in A172 cells, revealing a mesenchymal-specific mechanism absent in free WIN, which primarily modulated CB1/CB2. These findings position SMA-WIN as a promising candidate for precision GBM therapy, particularly for resistant mesenchymal subtypes, paving the way for in vivo validation to confirm blood-brain barrier penetration and clinical translation.

Skeletal disorders in laying hens: a systematic review with a focus on non-cage housing systems and hemp-based dietary interventions for bone health

1. The poultry sector is possibly the fastest growing and most flexible of all livestock sectors. At present, the main changes to the table egg production system include the gradual abandonment and closure of all cage-housing systems for laying hens, driven by animal welfare concerns and stricter legislation in many countries. In the future, keeping hens in enriched cage systems may be restricted or phased out in response to evolving animal welfare guidelines and public demand. To meet the welfare and behavioural requirements of the hens, it is desirable to choose housing on litter or housing in aviaries as a substitute for housing in enriched cages.2. The objective of this systematic review was to examine non-cage housing systems and hemp-based dietary interventions in relation to skeletal health in laying hens. This review focussed on the risks associated with alternative housing systems, particularly the increased incidence of bone fractures and the potential of nutritional strategies to mitigate skeletal disorders, including osteoporosis.3. The proportion of hens housed in non-cage alternative housing systems is currently increasing sharply but carries certain risks. One of the most significant concerns is skeletal integrity, as hens in aviaries experience a higher rate of keel bone fractures due to collisions, falls and deviations thought to be related to internal pressure. Numerous studies have shown that the incidence of keel bone damage (i.e. fractures and deviations) was greater in aviaries compared to enriched cage systems.4. Optimal skeletal health can be supported through proper nutrition, which plays a crucial role in bone metabolism. Key nutritional elements, including calcium, vitamins D, E and K, polyunsaturated fatty acids and hemp-based products, have been shown to be beneficial in preventing skeletal disorders and associated fractures due to their specific roles in maintaining bone structure and strength.

Advances in targeted liquid chromatography-tandem mass spectrometry methods for endocannabinoid and N-acylethanolamine quantification in biological matrices: A systematic review

Liquid chromatography paired with tandem mass spectrometry (LC-MS/MS) is the gold standard in measurement of endocannabinoid concentrations in biomatrices. We conducted a systematic review of literature to identify advances in targeted LC-MS/MS methods in the period 2017-2024. We found that LC-MS/MS methods for endocannabinoid quantification are relatively consistent both across time and across biomatrices. Recent advances have primarily been in three areas: (1) sample preparation techniques, specific to the chosen biomatrix; (2) the range of biomatrices tested, recently favoring blood matrices; and (3) the breadth of endocannabinoid and endocannabinoid-like analytes incorporated into assays. This review provides a summary of the recent literature and a guide for researchers looking to establish the best methods for quantifying endocannabinoids in a range of biomatrices.

The endocannabinoid system in cancer biology: a mini-review of mechanisms and therapeutic potential

The Endocannabinoid System (ECS) plays a critical role in maintaining physiological homeostasis, influencing a range of processes such as neuroprotection, inflammation, energy metabolism, and immune responses. Comprising cannabinoid receptors (CB1 and CB2), endogenous ligands (endocannabinoids), and the enzymes responsible for their synthesis and degradation, the ECS has attracted increasing attention in cancer research. Cannabinoid receptor activation has been associated with the regulation of cancer-related processes, including cell proliferation, apoptosis, and angiogenesis, suggesting that the ECS may have a role in tumor progression and cancer treatment. Preclinical studies have shown that cannabinoids, through their interaction with CB1 and CB2 receptors, can inhibit tumor cell growth, induce programmed cell death, and suppress the formation of new blood vessels in various cancer models. Despite these encouraging findings, the clinical translation of ECS-targeted therapies remains in its early stages. The complexity of tumor heterogeneity, the variability in patient responses, and the challenges associated with the pharmacokinetics of cannabinoids are significant obstacles to the broader application of these findings in clinical settings. This review provides an overview of the current understanding of the ECS's involvement in cancer biology, focusing on key mechanisms by which it may influence carcinogenesis. Additionally, we discuss the therapeutic potential of targeting the ECS in cancer treatment, while highlighting the limitations and uncertainties that need to be addressed through ongoing research.

20:4-NAPE induced changes of mechanical sensitivity and DRG neurons excitability are concentration dependent and mediated via NAPE-PLD

Alterations in the excitability of dorsal root ganglion (DRG) neurons are critical in the pathogenesis of acute and chronic pain. Neurotransmitter release from the terminals of DRG neurons is regulated by cannabinoid receptor 1 (CB1) and transient receptor potential vanilloid 1 (TRPV1), both activated by anandamide (AEA). In our experiments, the AEA precursor N-arachidonoylphosphatidylethanolamine (20:4-NAPE) was used to study the modulation of nociceptive DRG neurons excitability using K+-evoked Ca2+ transients. Intrathecal administration was used to evaluate in vivo effects. Application of 20:4-NAPE at lower concentrations (10 nM - 1 µM) decreased the excitability of DRG neurons, whereas the higher (10 µM) increased it. Both effects of 20:4-NAPE were blocked by the N-acylphosphatidylethanolamine phospholipase D (NAPE-PLD) inhibitor LEI-401. Similarly, lower concentrations of externally applied AEA (1 nM - 10 nM) inhibited DRG neurons, whereas higher concentration (100 nM) did not change it. High AEA concentration (10 µM) evoked Ca2+ transients dependent on TRPV1 activation in separate experiments. Inhibition of the CB1 receptor by PF514273 (400 nM) prevented the 20:4-NAPE- and AEA-induced inhibition, whereas TRPV1 inhibition by SB366791 (1 µM) prevented the increased DRG neuron excitability. In behavioral tests, lower 20:4-NAPE concentration caused hyposensitivity, while higher evoked mechanical allodynia. Intrathecal LEI-401 prevented both in vivo effects of 20:4-NAPE. These results highlight anti- and pro-nociceptive effects of 20:4-NAPE mediated by CB1 and TRPV1 in concentration-dependent manner. Our study underscores the complexity of endocannabinoid signaling in pain transmission modulation and highlights 20:4-NAPE as a potential therapeutic target, offering new insights for developing analgesic strategies.

Pannexin 1 channels: A bridge between synaptic plasticity and learning and memory processes

The Pannexin 1 channel is a membrane protein widely expressed in various vertebrate cell types, including microglia, astrocytes, and neurons within the central nervous system. Growing research has demonstrated the significant involvement of Panx1 in synaptic physiology, such as its contribution to long-term synaptic plasticity, with a particular focus on the hippocampus, an essential structure for learning and memory. Investigations studying the role of Panx1 in synaptic plasticity have utilized knockout animal models and channel inhibition techniques, revealing that the absence or blockade of Panx1 channels in this region promotes synaptic potentiation, dendritic arborization, and spine formation. Despite substantial progress, the precise mechanism by which Panx1 regulates synaptic plasticity remains to be determined. Nevertheless, evidence suggests that Panx1 may exert its influence by releasing signaling molecules, such as adenosine triphosphate (ATP), or through the clearance of endocannabinoids (eCBs). This review aims to comprehensively explore the current literature on the role of Panx1 in synapses. By examining relevant articles, we seek to enhance our understanding of Panx1's contribution to synaptic fundamental processes and the potential implications for cognitive function.

Integrating endocannabinoid signaling, CCK interneurons, and hippocampal circuit dynamics in behaving animals

The brain's endocannabinoid signaling system modulates a diverse range of physiological phenomena and is also involved in various psychiatric and neurological disorders. The basic components of the molecular machinery underlying endocannabinoid-mediated synaptic signaling have been known for decades. However, limitations associated with the short-lived nature of endocannabinoid lipid signals had made it challenging to determine the spatiotemporal specificity and dynamics of endocannabinoid signaling in vivo. Here, we discuss how novel technologies have recently enabled unprecedented insights into endocannabinoid signaling taking place at specific synapses in behaving animals. In this review, we primarily focus on cannabinoid-sensitive inhibition in the hippocampus in relation to place cell properties to illustrate the potential of these novel methodologies. In addition, we highlight implications of these approaches and insights for the unraveling of cannabinoid regulation of synapses in vivo in other brain circuits in both health and disease.

The Hunt for the Putative Epoxyeicosatrienoic Acid Receptor

Epoxyeicosatrienoic acids, or EETs, are signaling molecules formed by the metabolism of arachidonic acid by cytochrome P450 enzymes. They are well-known for their anti-inflammatory effects, their ability to lower blood pressure, and benefits to cardiovascular outcomes. Despite the wealth of data demonstrating their physiological benefits, the putative high-affinity receptor that mediates these effects is yet to be identified. The recent report that the sphingosine-1-phosphate receptor 1 (S1PR1) is a high-affinity receptor for a related epoxy lipid prompted us to ask, "Why has the putative EET receptor not been discovered yet? What information about the discoveries of lipid epoxide receptors can help us identify the putative EET receptor?" In this review, we summarize the evidence supporting that the putative EET receptor exists. We then review the data showing EETs binding to other, low-affinity receptors and the discovery of receptors for similar lipid metabolites that can serve as a model for identifying the putative EET receptor. We hope this review will revitalize the search for this important receptor, which can facilitate the development of anti-inflammatory and cardiovascular therapeutics.

Structure-activity relationship studies and pharmacological evaluation of 4-phenylthiazoles as dual soluble epoxide hydrolase/fatty acid amide hydrolase inhibitors

Forty-two 4-phenylthiazole analogs, organized in two libraries 4a-u and 6a-u, were prepared and biologically evaluated in human fatty acid amide hydrolase (FAAH), and human, rat and mouse soluble epoxide hydrolase (sEH) inhibition assays. This structure-activity relationship (SAR) study explores the impact of electronic and steric changes on the molecule's potency and binding affinity to better understand the structural features important for dual sEH/FAAH inhibition which will guide the development of novel treatments for pain and inflammation. Our SAR revealed that electron-donating groups on the aromatic ring of the 4-phenylthiazole moiety are particularly well tolerated by both enzymes when placed at the ortho, meta and para positions; however, the overall 3D shape of the molecule is very important for the potent FAAH inhibition, suggesting more restricted size of the FAAH binding pocket compared to sEH binding pocket. Two selected dual inhibitors, 4p and 4s, were tested in the rat liver microsomes stability assays and evaluated in vivo in the formalin test. Systemic administration of 4p and 4s via intraperitoneal injection decreased nociceptive behavior (i.e., licking of the injected paw) in male rats, and this effect was dose-dependent for both compounds. Two doses, 1 and 3 mg/kg of 4p, decreased nociceptive behavior to a similar extent to that of 30 mg/kg ketoprofen, a traditional nonsteroidal anti-inflammatory drug. However, only 3 mg/kg of 4s decreased nociceptive behavior compared to vehicle-treated animals, and this effect was comparable to ketoprofen-treated animals. Taken together, these findings reveal the antinociceptive potential of 4-phenylthiazole-based dual FAAH and sEH inhibitors and suggest pharmacodynamic differences within this class of inhibitors despite similar potencies in vitro.

Recent Progress in N-Acylethanolamine Research: Biological Functions and Metabolism Regulated by Two Distinct N-Acyltransferases: cPLA2ε and PLAAT Enzymes

N-Acylethanolamines (NAEs) are a class of lipid mediators that consist of long-chain fatty acids condensed with ethanolamine and exert various biological activities depending on their fatty acyl groups. NAEs are biosynthesized from membrane phospholipids by two-step reactions or alternative multi-step reactions. In the first reaction, N-acyltransferases transfer an acyl chain from the sn-1 position of phospholipids to the amino group (N position) of phosphatidylethanolamine (PE), generating N-acyl-PE (NAPE), a precursor of NAE. So far, two types of N-acyltransferases have been identified with different levels of Ca2+-dependency: cytosolic phospholipase A2 ε (cPLA2ε) as a Ca2+-dependent N-acyltransferase and phospholipase A and acyltransferase (PLAAT) enzymes as Ca2+-independent N-acyltransferases. Recent in vivo studies using knockout mice with cPLA2ε and PLAAT enzymes, combined with lipidomic approaches, have clarified their roles in the skin and brain and in other physiological events. In this review, we summarize the current understanding of the functions and properties of these enzymes.

Exploratory study on plasma Acylglycerol and Acylethanolamide dysregulation in substance use and attention-deficit/hyperactivity disorder: Implications for novel biomarkers in dual diagnosis

Substance use disorder (SUD) is a major global public health challenge, frequently co-occurring with psychiatric conditions such as attention-deficit/hyperactivity disorder (ADHD). Endocannabinoid system (ECS) dysregulation has been implicated in both SUD and ADHD, but the interplay between these conditions remains poorly understood. This study investigates plasma concentrations of endocannabinoid-congeners in individuals with SUD, with and without comorbid ADHD, to identify potential biomarkers. This exploratory study included 469 participants divided into three groups: (1) healthy controls (n = 136), (2) patients with SUD without ADHD (n = 267), and (3) patients with SUD and comorbid ADHD (n = 66). Plasma concentrations of 12 endocannabinoid-related molecules, including acylglycerols (2-AG, 2-LG, 2-OG) and acylethanolamides (AEA, DEA, DHEA, DGLEA, LEA, OEA, PEA, POEA, and SEA), were quantified using high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS). A multinomial Elastic Net regression model was applied to assess their biomarker potential. Patients with SUD exhibited significantly lower plasma concentrations of 2-AG and 2-LG compared to controls, while most acylethanolamides were elevated, except for POEA and SEA. ADHD comorbidity was associated with lower concentrations of 2-AG, 2-LG, AEA, DGLEA, DHEA, and SEA, while PEA was elevated. Machine learning analysis identified AEA, OEA, PEA, and SEA as key biomarkers, achieving an accuracy of 72.1 % and an ROC-AUC of 0.77. This study suggests distinct ECS alterations in SUD and comorbid ADHD, highlighting endocannabinoid-congeners as potential biomarkers. Future research should validate these findings in larger cohorts and explore ECS-targeted therapeutic interventions for dual-diagnosis populations.

Research mapping of cannabinoids and endocannabinoid system in cancer over the past three decades: insights from bibliometric analysis

Background

The cannabinoids and endocannabinoid system are thought to play critical roles in multiple signaling pathways in organisms, and extensive evidence from preclinical studies indicated that cannabinoids and endocannabinoids displayed anticancer potential. This study aimed to summarize the research of cannabinoids and endocannabinoid system in cancer through bibliometric analysis.

Methods

Relevant literature in the field of cannabinoids and endocannabinoid system in cancer published during 1995-2024 were collected from the Web of Science Core Collection database. VOSviewer and SCImago Graphica were applied to perform bibliometric analysis of countries, institutions, authors, journals, documents, and keywords.

Results

A total of 3,052 publications were identified, and the global output exhibited a generally upward trend over the past 3 decades. The USA had the greatest number of publications and citations in this research field. Italian National Research Council led in terms of publication, while Complutense University of Madrid had the highest total citations. Vincenzo Di Marzo was the leading author in this field with the greatest number of publications and citations. The co-occurrence of keywords revealed that the research frontiers mainly included "cannabinoids", "endocannabinoid system", "cancer", "anandamide", "cannabidiol", "cannabinoid receptor", "apoptosis", and "proliferation".

Conclusion

Our results revealed that the research of cannabinoids and endocannabinoid system in cancer would receive continuous attention. The USA and Italy have made remarkable contributions to this field, supported by their influential institutions and prolific scholars. The research emphasis has evolved from basic functional characterization to mechanistic exploration of disease pathways and translational applications within multidisciplinary framework.

High Stakes: Exploring the Impact of Cannabis Use in Pregnancy and Lactation

Cannabis is the most commonly used federally illicit substance during pregnancy in the United States, with an estimated prevalence of 3% to 30%. The American College of Obstetricians and Gynecologists and the American Academy of Pediatrics discourage cannabis use during pregnancy and breastfeeding due to safety concerns for the fetus and infant. Despite these recommendations, nearly half of active cannabis users continue use in pregnancy. In this review, we summarize cannabis pharmacology and metabolism with a focus on delta-9-tetrahydrocannabinol, the psychoactive component of the cannabis plant, highlighting its significance in quantifying exposure and the impact on outcomes studies. We also provide a concise review of current evidence on the effects of perinatal cannabis use and pregnancy, infant, and childhood outcomes, acknowledging the limitations of this evidence. Additionally, we provide targeted counseling recommendations for harm reduction strategies and lactation considerations for birthing parents who use cannabis.

The PLAAT family as phospholipid-related enzymes

The phospholipase A and acyltransferase (PLAAT) family is a group of structurally related proteins that are conserved among vertebrates. In humans, the family comprises five members (PLAAT1-5), which share common domain structures, and functions as phospholipase A1/A2 and acyltransferase enzymes. Regarding acyltransferase activities, PLAATs produce N-acyl-phosphatidylethanolamines, which serve as the precursor of bioactive N-acylethanolamines (NAEs). Recent evidence strongly suggests that PLAAT proteins play a crucial role in maintaining homeostasis in various organelles, such as the endoplasmic reticulum, lysosomes, mitochondria, and peroxisomes. In this process, PLAAT proteins bind to organelles and degrade them in an enzyme activity-dependent manner. Their physiological significance was revealed by the inability of PLAAT-deficient animals to degrade organelles during the maturation of the eye lens, resulting in the development of cataracts. Furthermore, the deficiency of PLAAT1, 3, and 5 in mice caused resistance to high-fat diet-induced fatty liver, the lean phenotype represented by a marked decrease in adipose tissue mass, and the exacerbation of testicular inflammation due to decreased levels of anti-inflammatory NAEs, respectively. In addition, human PLAAT3 was identified as a causative gene for lipodystrophy. We herein provide an overview of the molecular and biological properties of PLAAT proteins.

Expression, Distribution and Function of the Transient Receptor Potential Vanilloid Type 1 (TRPV1) in Endometrial Cancer

The transient receptor potential vanilloid 1 receptor (TRPV1) is a calcium-sensitive membrane receptor activated by capsaicin and the endocannabinoid, anandamide (AEA). Once activated in vitro, endometrial cancer (EC) cell growth appears to be inhibited through increased apoptosis, but the mechanism remains unclear. Our aim was to investigate the expression and distribution of TRPV1 in normal and cancerous endometria and to determine the precise in vitro mechanism of decreased EC cellular growth. TRPV1 expression in patients with endometrial carcinoma (15 Type 1 EC, six Type 2 EC) and six normal patients (atrophic endometria) was assessed using quantitative RT-PCR and immunohistochemistry (IHC). Additionally, immunohistochemical staining for the proliferation marker Ki-67, the pro-apoptotic marker BAX and the anti-apoptotic marker Bcl-2 were explored. TRPV1 transcript (p = 0.0054) and immunoreactive protein (p < 0.0001) levels were significantly reduced in all EC tissues when compared to control (atrophic) endometria. The almost 50% reduction in TRPV1 transcript levels was mirrored by an almost complete loss of immunoreactive TRPV1 protein. The increased proliferation (Ki-67) of EC tissues correlated with the expression of mutated BAX and inversely correlated to Bcl-2, but only in Type 2 EC samples. In vitro, AEA caused a decrease in Ishikawa cell numbers, whilst capsaicin did not, suggesting the anti-proliferative effect of AEA in EC cells is not via the TRPV1 receptor. In conclusion, the loss of TRPV1 expression in vivo plays a role in the aetiopathogenesis of EC. Activation of cells by AEA also probably promotes EC cell loss through a pro-apoptotic mechanism not involving TRPV1.

Cannabinoid receptor deficiencies drive immune response dynamics in Salmonella infection

This study investigated the roles of cannabinoid receptors 1 and 2 (CB1R and CB2R) in regulating host responses to Salmonella Typhimurium in C57BL/6 mice. The absence of both receptors significantly impaired host resilience, as evidenced by increased weight loss, deteriorated body condition, and reduced survival following infection. Notably, CB1R deficiency resulted in more pronounced weight loss and heightened susceptibility to bacterial proliferation, as demonstrated by increased Salmonella dissemination to organs. In addition, both CB1R and CB2R knockout mice exhibited alterations in immune cell recruitment and cytokine production. CB1R-KO mice displayed increased T cell and macrophage populations, whereas CB2R-KO mice showed a reduction in NK cells, indicating receptor-specific effects on immune cell mobilization. Cytokine profiling of macrophages post-infection revealed that CB1R-KO mice had reduced IL-10 levels, along with increased IL-6 and TGF-β, suggesting a dysregulated polarization state that combines pro-inflammatory and regulatory elements. In contrast, CB2R-KO mice exhibited a profile consistent with a more straightforward pro-inflammatory shift. Furthermore, microbiota analysis demonstrated that CB2R-KO mice experienced significant gut dysbiosis, including reduced levels of beneficial Lactobacillus and Bifidobacterium species and an increase in pro-inflammatory Alistipes species post-infection. Functional microbiome analysis further indicated declines in key metabolic pathways, such as the Bifidobacterium shunt, L-glutamine biosynthesis, and L-lysine biosynthesis, suggesting microbiota-driven immune dysregulation. Together, these findings highlight the distinct, non-redundant roles of CB1R and CB2R in modulating innate immunity, host defense, and microbiota composition during bacterial infections.

Changes in peripheral endocannabinoid levels in substance use disorders: a review of clinical evidence

Background: The endocannabinoid (eCB) system is a key modulator of stress and reward and is impacted by alcohol and drug use. Recently, the eCB system has been highlighted as a potential novel target in the treatment of substance use disorders (SUDs).Objectives: Understanding how chronic substance use impacts the function of the eCB system can provide a mechanistic rationale for targeting this system in the treatment of SUDs.Methods: A comprehensive review of studies assessing concentrations of eCB ligands N-arachidonoyl ethanolamine (anandamide; AEA) and 2-arachidonoylglycerol (2-AG) in individuals with a SUD diagnosis was performed using all EBSCO databases, PubMed, and Google Scholar. Methods and results related to eCB concentrations, diagnosis, and other factors (e.g. treatment status) were extracted from papers written in English and published in peer-reviewed journals before May 22, 2024.Results: Fifteen studies were reviewed; three in alcohol use disorder (AUD), three in cannabis use disorder (CUD), four in cocaine use disorder, one in opioid use disorder (OUD) and four across SUDs. Generally, AEA concentrations were usually, but not always, increased in AUD, CUD, OUD, and cocaine use disorder. 2-AG concentrations were measured less often but were increased in CUD and decreased in cocaine use disorder.Conclusions: Studies generally support the hypothesis that chronic substance use can impact eCB levels, most often with increased AEA and decreased (or not quantified) 2-AG concentrations, though results were often conflicting. Variability in methodology and study design may limit generalizability across studies.

CBD and the 5-HT1A receptor: A medicinal and pharmacological review

Cannabidiol (CBD), a phytocannabinoid, has emerged as a promising candidate for addressing a wide array of symptoms. It has the ability to bind to multiple proteins and receptors, including 5-HT1AR, transient receptor potential vanilloid 1 (TRPV1), and cannabinoid receptors. However, CBD's pharmacodynamic interaction with 5-HT1AR and its medicinal outcomes are still debated. This review explores recent literature to elucidate these questions, highlighting the neurotherapeutic outcomes of this pharmacodynamic interaction and proposing a signaling pathway underlying the mechanism by which CBD desensitizes 5-HT1AR signaling. A comprehensive survey of the literature underscores CBD's multifaceted neurotherapeutic effects, which include antidepressant, anxiolytic, neuroprotective, antipsychotic, antiemetic, anti-allodynic, anti-epileptic, anti-degenerative, and addiction-treating properties, attributable in part to its interactions with 5-HT1AR. Furthermore, evidence suggests that the pharmacodynamic interaction between CBD and 5-HT1AR is contingent upon dosage. Moreover, we propose that CBD can induce desensitization of 5-HT1AR via both homologous and heterologous mechanisms. Homologous desensitization involves the recruitment of G protein-coupled receptor kinase 2 (GRK2) and β-arrestin, leading to receptor endocytosis. In contrast, heterologous desensitization is mediated by an elevated intracellular calcium level or activation of protein kinases, such as c-Jun N-terminal kinase (JNK), through the activity of other receptors.

Cannabidiol induces autophagy via CB1 receptor and reduces α-synuclein cytosolic levels

Numerous studies have explored the role of cannabinoids in neurological conditions, chronic pain and neurodegenerative diseases. Restoring autophagy has been proposed as a potential target for the treatment of neurodegenerative diseases. In our study, we used a neuroblastoma cell line that overexpresses wild-type α-synuclein to investigate the effects of cannabidiol on autophagy modulation and reduction in the level of cytosolic α-synuclein. Our results demonstrated that cannabidiol enhances the accumulation of LC3-II- and GFP-LC3-positive vesicles, which indicates an increase in autophagic flux. In addition, cannabidiol-treated cells showed a reduction in cytosolic α-synuclein levels. These effects were inhibited when the cells were treated with a CB1 receptor-selective antagonist, which indicates that the biological effects of cannabidiol are mediated via its interaction with CB1 receptor. Additionally, we also observed that cannabinoid compounds induce autophagy and α-synuclein degradation after they interact with the CB1 receptor. In summary, our data suggest that cannabidiol induces autophagy and reduces cytosolic α-synuclein levels. These biological effects are mediated preferentially through the interaction of cannabidiol with CB1 receptors, and therefore, cannabinoid compounds that act selectively on this receptor could represent a new approach for autophagy modulation and degradation of protein aggregates.

CB1 receptor signaling: Linking neuroplasticity, neuronal types, and mental health outcomes

The endocannabinoid system (ECS) is crucial in the pathophysiology of mental disorders. Historically, cannabis has been utilized for centuries to mitigate symptoms of anxiety and depression; however, the precise role of cannabinoids in these conditions has only recently garnered extensive research attention. Despite the growing body of literature on the ECS and its association with mental health, several critical questions remain unresolved. This review primarily focuses on cannabinoid CB1 receptors (CB1R), providing an examination of their regulatory roles in states related to mental disorders. Evidence suggests that CB1R distribution occurs among various neuronal types, astrocytes, and subcellular membranes across multiple brain regions, potentially exhibiting both analogous and antagonistic effects. Additionally, various forms of stress have been shown to produce divergent impacts on CB1R signaling pathways. Furthermore, numerous CB1R agonists demonstrate biphasic, dose-dependent effects on anxiety and depression; specifically, low doses may exert anxiolytic effects, while higher doses can induce anxiogenic responses, a phenomenon observed in both rodent models and human studies. We also discuss the diverse underlying mechanisms that mediate these effects. We anticipate that this review will yield valuable insights into the role of CB1R in mental disorders and provide a framework for future research endeavors on CB1R and the ECS. This knowledge may ultimately inform therapeutic strategies aimed at alleviating symptoms associated with mental health conditions.

The Endocannabinoid System: Implications in Gastrointestinal Physiology and Pathology

The endocannabinoid system (ECS), composed of receptors, endocannabinoids, and enzymes that regulate biosynthesis and degradation, plays a fundamental role in the physiology and pathology of the gastrointestinal tract, particularly in the small and large intestine and liver. Specifically, cannabinoid receptor type 1 (CB1R) and cannabinoid receptor type 2 (CB2R), located principally in the nervous system and immune cells, orchestrate processes such as intestinal motility, intestinal and hepatic inflammation, and energy metabolism, respectively. The main endocannabinoids, anandamide (AEA) and 2-arachidonoylglycerol (2-AG), influence appetite, body weight regulation, and inflammatory states and thus have implications in obesity, non-alcoholic fatty liver disease (NAFLD) and irritable bowel syndrome (IBS). Recent studies have highlighted the therapeutic potential of targeting the ECS to modulate gastrointestinal and metabolic diseases. In particular, peripheral CB1R antagonists and CB2R agonists have shown efficacy in treating intestinal inflammation, reducing hepatic steatosis, and controlling IBS symptoms. Moreover, the ECS is emerging as a potential target for the treatment of colorectal cancer, acting on cell proliferation and apoptosis. This review highlights the opportunity to exploit the endocannabinoid system in the search for innovative therapeutic strategies, emphasizing the importance of a targeted approach to optimize treatment efficacy and minimize side effects.

Mechanisms and pharmacotherapy of cancer cachexia-associated anorexia

Cachexia is a multifactorial metabolic syndrome characterized by weight and skeletal muscle loss caused by underlying illnesses such as cancer, heart failure, and renal failure. Inflammation, insulin resistance, increased muscle protein degradation, decreased food intake, and anorexia are the primary pathophysiological drivers of cachexia. Cachexia causes physical deterioration and functional impairment, loss of quality of life, lower response to active treatment, and ultimately morbidity and mortality, while the difficulties in tackling cachexia in its advanced phases and the heterogeneity of the syndrome among patients require an individualized and multidisciplinary approach from an early stage. Specifically, strategies combining nutritional and exercise interventions as well as pharmacotherapy that directly affect the pathogenesis of cachexia, such as anti-inflammatory, metabolism-improving, and appetite-stimulating agents, have been proposed, but none of which have demonstrated sufficient evidence to date. Nevertheless, several agents have recently emerged, including anamorelin, a ghrelin receptor agonist, growth differentiation factor 15 neutralization therapy, and melanocortin receptor antagonist, as candidates for ameliorating anorexia associated with cancer cachexia. Therefore, in this review, we outline cancer cachexia-associated anorexia and its pharmacotherapy, including corticosteroids, progesterone analogs, cannabinoids, anti-psychotics, and thalidomide which have been previously explored for their efficacy, in addition to the aforementioned novel agents, along with their mechanisms.

Acute cannabidiol treatment reverses behavioral impairments induced by embryonic valproic acid exposure in male mice

Cannabidiol (CBD), the major non-psychotomimetic compound of the Cannabis sativa plant, has shown promising effects in addressing various symptoms associated with autism spectrum disorder (ASD). This neurodevelopmental disorder typically impacts cognitive, behavioral, social communication, and motor skills domains. However, effective treatments for the wide range of symptoms associated with the disorder are limited and may trigger undesirable effects. Embryonic exposure to valproic acid (VPA, 500 mg/kg at 12° day embryonic age) in rodents is a consolidated environmental model for studying behavioral and molecular characteristics related to ASD. Therefore, this study aimed to evaluate whether acute CBD could reverse behavioral impairments in adult mice (eight weeks) exposed to VPA in the embryonic period in four distinct trials. In independent groups of animals, the following assays were conducted: I) Pre-Pulse Inhibition Test (PPI), II) Marble Burying, III) Social Interaction, IV) Actimeter Test, and V) Novel Object Recognition Test (NOR). In the PPI paradigm, mice exposed to VPA showed PPI impairment, and CBD (30 and 60 mg/kg) reversed this disruption. CBD (60 mg/kg) respectively decreased the number of buried marbles, improved social interaction time, but failed to reduce stereotyped-like movements in the VPA group. In NOR test CBD at both doses reversed the impairment in index of recognition induced in VPA group. These findings suggest that acute CBD administration can ameliorate behavioral impairments associated with ASD in a well-established animal model for studying this neurodevelopmental disorder.

Muscarinic cannabinoid suppression of excitation, a novel form of coincidence detection

Δ9-tetrahydrocannabinol (THC), the chief psychoactive ingredient of cannabis, acts in the brain primarily via cannabinoid CB1 receptors. These receptors are implicated in several forms of synaptic plasticity - depolarization-induced suppression of excitation (DSE), metabotropic suppression of excitation (MSE), long term depression (LTD) and activation-dependent desensitization. Cultured autaptic hippocampal neurons express all of these, illustrating the rich functional and temporal heterogeneity of CB1 at a single set of synapses. Here we report that coincident activation of muscarinic acetylcholine receptors and elicitation of DSE in autaptic hippocampal neurons results in a substantial (∼40 %) and temporally precise inhibition of excitatory transmission lasting ∼10 minutes. Its induction is blocked by CB1 and muscarinic M3/M5 receptor antagonists and is absent in CB1 receptor knockout neurons. Notably, once it is established, inhibition is reversed by a CB1, but not a muscarinic, antagonist, suggesting that the inhibition occurs via persistent activation of CB1 receptors. We refer to this inhibition as muscarinic cannabinoid suppression of excitation (MCSE). MCSE can be mimicked by coapplication of muscarinic and cannabinoid agonists and requires Ca2+-release from internal stores. As such, MCSE represents a novel and targeted form of coincidence detection - important for many modes of learning and memory -- between cannabinoid and muscarinic signaling systems that elicits a medium-duration depression of synaptic signaling. Given the known roles of muscarinic and cannabinoid receptors in the hippocampus, MCSE may be important in the modulation of hippocampal signaling at the site of septal inputs, with potential implications for learning and memory, epilepsy and addiction.

Selective blockade of cannabinoid receptors influences motoneuron survival and glial responses after neonatal axotomy

Sciatic nerve crush in neonatal rats leads to an extensive death of motor and sensory neurons, serving as a platform to develop new neuroprotective approaches. The endocannabinoid system plays important neuromodulatory roles and has been involved in neurodevelopment and neuroprotection. The present work investigated the role of the cannabinoid receptors CB1 and CB2 in the neuroprotective response after neonatal axotomy. CB1 and CB2 antagonists (AM251 and AM630, respectively) were used after sciatic nerve crush in 2-day-old Wistar rats. Five days after lesion and treatment, the rats were perfused, and the spinal cords and dorsal root ganglia (DRG) were obtained and processed to investigate neuronal survival and immunohistochemistry changes, or RT-qPCR analysis. Motoneuron survival analysis showed that blocking CB2 alone or in combination with CB1 was neuroprotective. This effect was associated with a decrease in astrogliosis and microglial reaction. Interestingly, Cnr1 (CB1) and Bdnf gene transcripts were downregulated in the spinal cords of the antagonist-treated groups. Despite no intergroup difference regarding neuronal survival in the DRG, the simultaneous blockade of CB1 and CB2 receptors led to an increased expression of both Cnr1 and Cnr2, combined with Gdnf upregulation. The results indicate that the selective antagonism of cannabinoid receptors facilitates neuroprotection and decreases glial reactivity, suggesting new potential treatment approaches.

Interaction between the dopaminergic and endocannabinoid systems promotes peripheral antinociception

BACKGROUND

Dopamine has been widely related to pain modulation, at central and peripheral levels. In this study we aimed to investigate the mechanisms involved in peripheral antinociception, evaluating the interaction between the dopaminergic and endocannabinoid systems in this event.

METHODS

Male Swiss mice (30-40 g) were pre-sensitized by administration of the hyperalgesic PGE2 (2 μg/paw). The nociceptive threshold was measured using the paw withdrawal test.

RESULTS

Dopamine (80 ng/paw) promoted antinociception. This effect was reversed by the CB1 and CB2 cannabinoid receptor antagonists AM251 (20, 40, and 80 μg/paw) and AM630 (25, 50, and 100 μg/paw). JZL (4 μg/paw), an inhibitor of the degradation of the 2-arachidonylglycerol (2-AG), potentiated the antinociceptive action of the submaximal dose of dopamine (5 ng/paw). While anandamide degradation and reuptake inhibitors (MAFP 0.5 μg/paw and VDM11 2.5 μg/paw) did not promote changes in intermediate antinociception induced by dopamine. Anandamide at a submaximal dose (12.5 ng/paw) promoted intermediate antinociception that was not potentiated by the administration of the dopamine reuptake inhibitor GBR 12783 (16 μg/paw). In contrast, the administration of GBR potentiated the intermediate antinociception induced by a submaximal dose of 2-AG (10 μg/paw). Furthermore, the dopaminergic receptor antagonists D2 Remoxipride (4 μg/paw) and D3 U99194 (16 μg/paw) reversed the antinociception mediated by the maximum dose of this endocannabinoid (20 μg/paw). In contrast, the D4 receptor antagonist L-745,870 (16 μg/paw) did not change the nociceptive threshold.

CONCLUSIONS

In this way, we demonstrate the interaction between the dopaminergic and endocannabinoid systems to promote analgesia peripherally.

International Symposium on Ruminant Physiology: The involvement of the endocannabinoid system in metabolic and inflammatory responses in dairy cows during negative energy balance

The endocannabinoid system (ECS) is involved in the regulation of energy metabolism, immune function and reproduction in mammals. The ECS is consisted of the endocannabinoid (eCB) ligands, enzymes, and cannabinoid receptors. In mammals, the cannabinoid-1 receptor (CB1/CNR1) is expressed in the central nervous system and in peripheral tissues; and its activation increases anabolic processes. The cannabinoid-2 receptor (CB2/CNR2) is most highly expressed in immune cells, and its activation exerts mainly anti-inflammatory effects. Until recently, little was known about the involvement of the ECS in physiological responses in dairy cows. As peripartum dairy cows undergo vast changes in energy metabolism and immune function, processes that are regulated by the ECS, several studies characterized ECS components in transition cows. Concentrations of eCB in the adipose tissue were higher postpartum (PP), and levels of the eCB N-arachidonoylethanolamide (AEA) were increased PP compared with prepartum. Exogenous injections of AEA to transition cows may increase adipose deposition, but did not affect feed intake. In vitro models showed that bovine adipocyte metabolism was differentially affected by CB1 agonists and antagonists in nonlactating non-gestating compared with PP cows. Thus, the responses of the PP dairy cows to ECS modulations may be related to the physiological and reproductive stage of the cow. Currently, whole-body ECS activation via agonists is mostly not feasible in vivo in livestock. Alternatively, downregulation of ECS activation can be achieved by supplementation of omega-3 (n-3) fatty acids. Indeed, in vivo studies with transition cows supplemented with n-3 showed a moderate downregulation of ECS components in the blood, adipose and liver, improved systemic insulin sensitivity, but evidently reduced insulin sensitivity in the adipose tissue PP. The abundance of CB1 was lower in immune cells, and anti-inflammatory effects were found in PP cows supplemented with n-3; possibly associating ECS downregulation with immune function. The physiological impact of ECS activation is an exciting and complex area of research, that could influence the physiology of dairy cows during metabolic and inflammatory challenges. Dairy cows may be an experimental model for ECS modulations, with broader relevance to female mammals. More research is required on how selective ECS activation/downregulation in tissues could affect immune-metabolic function in dairy cows.

Utilization of Cannabidiol in Post-Organ-Transplant Care

Cannabidiol (CBD) is one of the major phytochemical constituents of cannabis, Cannabis sativa, widely recognized for its therapeutic potential. While cannabis has been utilized for medicinal purposes since ancient times, its psychoactive and addictive properties led to its prohibition in 1937, with only the medical use being reauthorized in 1998. Unlike tetrahydrocannabinol (THC), CBD lacks psychoactive and addictive properties, yet the name that suggests its association with cannabis has significantly contributed to its public visibility. CBD exhibits diverse pharmacological properties, most notably anti-inflammatory effects. Additionally, it interacts with key drug-metabolizing enzyme families, including cytochrome P450 (CYP) and uridine 5'-diphospho-glucuronosyltransferase (UGT), which mediate phase I and phase II metabolism, respectively. By binding to these enzymes, CBD can inhibit the metabolism of co-administered drugs, which can potentially enhance their toxicity or therapeutic effects. Mild to moderate adverse events associated with CBD use have been reported. Advances in chemical formulation techniques have recently enabled strategies to minimize these effects. This review provides an overview of CBD, covering its historical background, recent clinical trials, adverse event profiles, and interactions with molecular targets such as receptors, channels, and enzymes. We particularly emphasize the mechanisms underlying its anti-inflammatory effects and interaction with drugs relevant to organ transplantation. Finally, we explore recent progress in the chemical formulation of CBD in order to enhance its bioavailability, which will enable decreasing the dose to use and increase its safety and efficacy.

Endocannabinoids facilitate transitory reward engagement through retrograde gain-control

Neuromodulatory signaling is poised to serve as a neural mechanism for gain control, acting as a crucial tuning factor to influence neuronal activity by dynamically shaping excitatory and inhibitory fast neurotransmission. The endocannabinoid (eCB) signaling system, the most widely expressed neuromodulatory system in the mammalian brain, is known to filter excitatory and inhibitory inputs through retrograde, pre-synaptic action. However, whether eCBs exert retrograde gain control to ultimately facilitate reward-seeking behaviors in freely moving mammals is not established. Using a suite of in vivo physiological, imaging, genetic and machine learning-based approaches, we report a fundamental role for eCBs in controlling behavioral engagement in reward-seeking behavior through a defined thalamo-striatal circuit.

Chemical Probes for Investigating the Endocannabinoid System

Cannabis sativa has been used therapeutically since early civilizations, with key cannabinoids Δ9-tetrahydrocannabinol (THC) 3.1 and cannabidiol characterized in the 1960s, leading to the discovery of cannabinoid receptors type 1 (CB1R) and type 2 (CB2R) and the endocannabinoid system (ECS) in the 1990s. The ECS, involving endogenous ligands like 2-arachidonoylglycerol (2-AG) 1.1, anandamide (N-arachidonoylethanolamine (AEA)) 1.2, and various proteins, regulates vital processes such as sleep, appetite, and memory, and holds significant therapeutic potential, especially for neurological disorders. Small molecule-derived pharmacological tools, or chemical probes, target key components of the ECS and are crucial for target validation, mechanistic studies, pathway elucidation, phenotypic screening, and drug discovery. These probes selectively interact with specific proteins or pathways, enabling researchers to modulate target activity and observe biological effects. When they carry an additional reporter group, they are referred to as labeled chemical probes. Developed through medicinal chemistry, structural biology, and high-throughput screening, effective chemical probes must be selective, potent, and depending on their purpose meet additional criteria such as cell permeability and metabolic stability.This chapter describes high-quality labeled and unlabeled chemical probes targeting ECS constituents that have been successfully applied for various research purposes. CB1R and CB2R, class A G protein-coupled receptors, are activated by 2-AG 1.1, AEA 1.2, and THC 3.1, with numerous ligands developed for these receptors. Imaging techniques like single-photon emission computed tomography, positron emission tomography, and fluorescently labeled CB1R and CB2R probes have enhanced CB receptor studies. CB2R activation generally results in immunosuppressive effects, limiting tissue injury. AEA 1.2 is mainly degraded by fatty acid amide hydrolase (FAAH) or N-acylethanolamine acid amidase (NAAA) into ethanolamine and arachidonic acid (AA) 1.3. FAAH inhibitors increase endogenous fatty acid amides, providing analgesic effects without adverse effects. NAAA inhibitors reduce inflammation and pain in animal models. Diacylglycerol lipase (DAGL) is essential for 2-AG 1.1 biosynthesis, while monoacylglycerol lipase (MAGL) degrades 2-AG 1.1 into AA 1.3, thus regulating cannabinoid signaling. Multiple inhibitors targeting FAAH and MAGL have been generated, though NAAA and DAGL probe development lags behind. Similarly, advancements in inhibitors targeting endocannabinoid (eCB) cellular uptake or trafficking proteins like fatty acid-binding proteins have been slower. The endocannabinoidome (eCBome) includes the ECS and related molecules and receptors, offering therapeutic opportunities from non-THC cannabinoids and eCBome mediators. Ongoing research aims to refine chemical tools for ECS and eCBome study, addressing unmet medical needs in central nervous system disorders and beyond.

Characterisation of the effects of the chemotherapeutic agent paclitaxel on neuropathic pain-related behaviour, anxiodepressive behaviour, cognition, and the endocannabinoid system in male and female rats

Paclitaxel (PTX) is a commonly used chemotherapeutic drug, however, one of its major adverse effects is chronic neuropathic pain, with the incidence being higher in women than in men. The neurobiological mechanisms behind this sex difference are still largely unclear, and the endocannabinoid system, which exhibits sexual dimorphism and plays a key role in pain regulation, is a promising area for further studies. The present study aimed to characterise pain-, cognition-, anxiety-, and depression-related behaviours in male and female rats following PTX administration, and associated alterations in the endocannabinoid system. After the induction of the model, pain-related behaviours were assessed using von Frey, Acetone Drop and Hargreaves' tests, Novel Object Recognition and T-Maze Spontaneous Alternation tests were used for cognition-related behaviours, Elevated Plus Maze, Open Field, and Light Dark Box tests were used to assess anxiety-related behaviours, and Sucrose Preference, Sucrose Splash, and Forced Swim tests for depression-related behaviours. At each time point analysed, animals treated with PTX exhibited mechanical and cold hypersensitivity, with females displaying lower hind paw withdrawal thresholds to mechanical stimulation than males. No PTX-induced alterations in the other behavioural tests were detected. Post-mortem measurement of endocannabinoid and related N-acylethanolamine levels in spinal cord and discrete brain regions revealed a PTX-induced increase of 2-Arachidonoyl Glycerol (2-AG), N-Palmitoylethanolamine (PEA) and N-Oleoylethanolamine (OEA) levels in the amygdala of male and female animals, but not in the other areas. Collectively, these results suggest that PTX causes similar long-lasting hypersensitivity to mechanical and cold stimuli, but not heat, in rats of both sexes, effects accompanied by increases in amygdalar levels of endocannabinoids and N-acylethanolamines.

Hair and Saliva Endocannabinoid and Steroid Hormone Analysis by Liquid Chromatography Paired with Tandem Mass Spectrometry

Endocannabinoids are lipid neurotransmitters that play an important part in human health. Recent methods have found that quantification of endocannabinoids in hair and saliva samples is possible using liquid chromatography paired with tandem mass spectrometry (LC-MS/MS). This chapter describes two simple sample preparation methods that can be used to prepare hair and saliva samples for analysis using LC-MS/MS. Our LC-MS/MS method can be applied to both hair and saliva samples and is sufficiently sensitive for endocannabinoid, as well as steroid hormone, quantification in both of these sample matrices. This chapter provides a comprehensive description of how this can be achieved and provides tips and tricks for troubleshooting problems users may experience.

Unveiling the toxicity of JWH-018 and JWH-019: Insights from behavioral and molecular studies in vivo and vitro

Due to the structural diversity and rapid prevalence of synthetic cannabinoids (SCs) in the market, the information linking the chemical structure of SCs to their toxicity remains scant, despite emerging in the 1970s. In the present study, we aimed to investigate the toxicity and underlying mechanisms of indole SCs JWH-018 and JWH-019 in mice (C57BL/6, male, 6-8 weeks old), zebrafish (AB strain, male, 4-5 months old) and modified human embryonic kidney (HEK) 293 T cells, using behavioral, pharmacokinetic, pharmacological approaches, and molecular docking. JWH-018 induced time- and dose-dependent cannabinoid-like effects in mice (administration dosages: 0.02, 0.1, and 0.5 mg/kg, i.p.), and yielded dose-dependent anxiogenic effects and lower aggression behavior in zebrafish (administration dosages: 0.01, 0.05, and 0.25 µg/g, i.p.), unlike JWH-019. These effects were blocked by the selective cannabinoid receptor 1 (CB1R) antagonist AM251. JWH-018, but not JWH-019, activated the CB1R-dependent extracellular signal-regulated kinase 1 and 2 (ERK1/2) pathway in vivo and in vitro. Molecular docking identified essential residues PHE268, PHE170, and TRP279 within CB1R as pivotal contributors to enhancing receptor-ligand associations. While both drugs had a similar binding pattern with shared linker binding pockets in CB1R, there were still differences in their spatial conformation. These findings shed light on the molecular pharmacology and activation mechanism of SCs for CB1R and should guide further research into the mechanisms underlying their deleterious effects in humans.

Cannabinol modulates the endocannabinoid system and shows TRPV1-mediated anti-inflammatory properties in human keratinocytes

Cannabinol (CBN) is a secondary metabolite of cannabis whose beneficial activity on inflammatory diseases of human skin has attracted increasing attention. Here, we sought to investigate the possible modulation by CBN of the major elements of the endocannabinoid system (ECS), in both normal and lipopolysaccharide-inflamed human keratinocytes (HaCaT cells). CBN was found to increase the expression of cannabinoid receptor 1 (CB1) at gene level and that of vanilloid receptor 1 (TRPV1) at protein level, as well as their functional activity. In addition, CBN modulated the metabolism of anandamide (AEA) and 2-arachidonoylglicerol (2-AG), by increasing the activities of N-acyl phosphatidylethanolamines-specific phospholipase D (NAPE-PLD) and fatty acid amide hydrolase (FAAH)-the biosynthetic and degradative enzyme of AEA-and that of monoacylglycerol lipase (MAGL), the hydrolytic enzyme of 2-AG. CBN also affected keratinocyte inflammation by reducing the release of pro-inflammatory interleukin (IL)-8, IL-12, and IL-31 and increasing the release of anti-inflammatory IL-10. Of note, the release of IL-31 was mediated by TRPV1. Finally, the mitogen-activated protein kinases (MAPK) signaling pathway was investigated in inflamed keratinocytes, demonstrating a specific modulation of glycogen synthase kinase 3β (GSK3β) upon treatment with CBN, in the presence or not of distinct ECS-directed drugs. Overall, these results demonstrate that CBN modulates distinct ECS elements and exerts anti-inflammatory effects-remarkably via TRPV1-in human keratinocytes, thus holding potential for both therapeutic and cosmetic purposes.

LC-MS/MS Quantification of Endocannabinoids in Tissues

Endocannabinoids (ECBs) are lipid-derived endogenous molecules with important physiological roles such as regulation of energy balance, immunity, or neural development. Quantitation of ECBs helps better understand their physiological role and modulation of biological processes. This chapter presents the simultaneous quantification of 14 ECBs and related molecules in the brain, liver, and muscle, as well as white and brown adipose tissue using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The dynamic range of the method has been tuned to cover the endogenous concentrations of these analytes given the fact that they are endogenously present at different orders of magnitude. Specifically, three groups are established: 0.5-5000 ng/mL for 2-oleoyl- and 2-linoleoylglycerol and arachidonic acid, 0.05-500 ng/mL for 2-arachidonoylglycerol, and 0.0005-0.5 ng/mL for anandamide, palmitoyl-, palmitoleoyl-, stearoyl-, oleoyl-, linoleoyl-, alpha-linolenoyl-, dihomo-gamma-linolenoyl-, docosahexaenoyl-, and pentadecanoylethanolamide.

Structural dynamics and binding of Caenorhabditis elegans lifespan-extending lipid binding protein-3 to polyunsaturated fatty acids

Intracellular lipid binding proteins (iLBPs) play crucial roles in lipid transport and cellular metabolism across the animal kingdom. Recently, a fat-to-neuron axis was described in Caenorhabditis elegans, in which lysosomal activity in the fat liberates polyunsaturated fatty acids (PUFAs) that signal to neurons and extend lifespan with durable fecundity. In this study, we investigate the structure and binding mechanisms of a lifespan-extending lipid chaperone, lipid binding protein-3 (LBP-3), which shuttles dihomo-γ-linolenic (DGLA) acid from intestinal fat to neurons. We present the first high-resolution crystal structure of LBP-3, which reveals a classic iLBP fold with an unexpected and unique homodimeric arrangement via interstrand interactions that is incompatible with ligand binding. We identify key ionic interactions that mediate DGLA binding within the lipid binding pocket. Molecular dynamics simulations further elucidate LBP-3's preferential binding to DGLA due to its rotational freedom and access to favorable binding conformations compared to other 20-carbon PUFAs. We also propose that LBP-3 dimerization may be a unique regulatory mechanism for lipid chaperones.

The Role of Cannabinoids and the Endocannabinoid System in the Treatment and Regulation of Nausea and Vomiting

Despite using the recommended anti-emetic treatments, control of nausea and vomiting is still an unmet need for cancer patients undergoing chemotherapy treatment. Few properly controlled clinical trials have evaluated the potential of exogenously administered cannabinoids or manipulations of the endogenous cannabinoid (eCB) system to treat nausea and vomiting. In this chapter, we explore the pre-clinical and human clinical trial evidence for the potential of exogenous cannabinoids and manipulations of the eCB system to reduce nausea and vomiting. Although there are limited high-quality human clinical trials, pre-clinical evidence suggests that cannabinoids and manipulations of the eCB system have anti-nausea/anti-emetic potential. The pre-clinical anti-nausea/anti-emetic evidence highlights the need for further evaluation of cannabinoids and manipulations of eCBs and other fatty acid amides in clinical trials.

Cannabinoids: Role in Neurological Diseases and Psychiatric Disorders

An impact of legalization and decriminalization of marijuana is the gradual increase in the use of cannabis for recreational purposes, which poses a potential threat to society and healthcare systems worldwide. However, the discovery of receptor subtypes, endogenous endocannabinoids, and enzymes involved in synthesis and degradation, as well as pharmacological characterization of receptors, has led to exploration of the use of cannabis in multiple peripheral and central pathological conditions. The role of cannabis in the modulation of crucial events involving perturbed physiological functions and disease progression, including apoptosis, inflammation, oxidative stress, perturbed mitochondrial function, and the impaired immune system, indicates medicinal values. These events are involved in most neurological diseases and prompt the gradual progression of the disease. At present, several synthetic agonists and antagonists, in addition to more than 70 phytocannabinoids, are available with distinct efficacy as a therapeutic alternative in different pathological conditions. The present review aims to describe the use of cannabis in neurological diseases and psychiatric disorders.

Research and Clinical Practice Involving the Use of Cannabis Products, with Emphasis on Cannabidiol: A Narrative Review

BACKGROUND

Emerging evidence supports cannabidiol (CBD) as a promising therapeutic compound for various health conditions, despite its approval as a medication (product for medical purposes) remaining restricted to a limited range of clinical indications. Simultaneously, the regulation of cannabis-derived products for medicinal and recreational use has expanded their global market availability to meet local community demands. This scenario presents a complex challenge for clinicians, researchers, and industry, as the global appeal of therapeutic uses of CBD is growing more rapidly than the scientific evidence supporting its safety and effectiveness.

OUTCOMES

A narrative review was conducted to discuss the best evidence regarding the pharmacological profile of CBD, its efficacy, and safety within the context of regulation and perspectives on the development of new cannabinoid-based drugs. Key articles addressing the various facets of this issue were selected for comprehensive analysis.

CONCLUSIONS

Clinicians and researchers may face unique challenges in understanding the pharmacological profile of CBD and the prospects for developing its clinical indications, given the heterogeneity of clinical terminologies and the quality and composition of cannabis-based medical products available on the market. More basic and clinical research that complies with regulatory agencies' testing guidelines, such as good manufacturing practices (GMPs), good laboratory practices (GLPs), and good clinical practices (GCPs), is needed to obtain approval for CBD or any other cannabinoid as a therapeutic for broader clinical indications.

A Sex-Dependent Cannabinoid CB1 Receptor Role in Circadian Tearing of the Mouse

Purpose

We have shown that cannabinoid CB1 receptors regulate both salivation and tearing, but for tearing, this regulation is sex dependent with opposing effects by sex. We investigated a potential interplay of circadian and cannabinoid regulation of tearing.

Methods

We measured cannabinoid and circadian regulation of tearing in CD1 strain mice as well as CB1 receptor protein expression using immunohistochemistry.

Results

We now report that CD1 strain mice have a circadian variation in basal tearing, differing by sex in terms of phase and amplitude. The amplitude of circadian variation in females is substantially dampened relative to males. Male CB1 receptor knockout mice do not differ from strain controls, but in female CB1 knockouts, the amplitude is enhanced and resembles that of WT males. This increased tearing is mimicked by the CB1 antagonist SR141716 (4 mg/kg, intraperitoneally [IP]), suggesting that tonic CB1 activation dampens female circadian tearing. Consistent with this, the cannabinoid receptor agonist CP55940 (0.5 mg/kg, IP) decreases tearing during the rest phase but increases tearing during the active phase in females. CB1 protein expression also differs by sex. While both males and females have CB1 receptors in parasympathetic inputs to the lacrimal gland, in female lacrimal glands, CB1 is also detected in myoepithethial cells.

Conclusions

Mice have a sex-dependent circadian cycle of tearing. The endogenous cannabinoid signaling system appears to mediate some circadian effects, albeit in a sex-dependent manner and via distinct cellular targets.