Endocannabinoid System: Chemical Characteristics and Biological Activity

The endocannabinoid system as a therapeutic target in neuropathic pain: a review

INTRODUCTION

This review highlights the critical role of the endocannabinoid system (ECS) in regulating neuropathic pain and explores the therapeutic potential of cannabinoids. Understanding the mechanisms of the ECS, including its receptors, endogenous ligands, and enzymatic routes, can lead to innovative treatments for chronic pain, offering more effective therapies for neuropathic conditions. This review bridges the gap between preclinical studies and clinical applications by emphasizing ECS modulation for better pain management outcomes.

AREAS COVERED

A review mapped the existing literature on neuropathic pain and the effects of modulating the ECS using natural and synthetic cannabinoids. This analysis examined ECS components and their alterations in neuropathic pain, highlighting the peripheral, spinal, and supraspinal mechanisms. This review aimed to provide a thorough understanding of the therapeutic potential of cannabinoids in the management of neuropathic pain.

EXPERT OPINION

Advances in cannabinoid research have shown significant potential for the management of chronic neuropathic pain. The study emphasizes the need for high-quality clinical trials and collaborative efforts among researchers, clinicians, and regulatory bodies to ensure safe and effective integration of cannabinoids into pain management protocols. Understanding the mechanisms and optimizing cannabinoid formulations and delivery methods are crucial for enhancing therapeutic outcomes.

Neurolipid systems: A new target for the treatment of dementia

Neurolipids comprise a diverse class of bioactive lipids that include molecules capable of activating G protein‐coupled receptors, thereby inducing systemic effects that contribute to the maintenance of homeostasis. Dementia, a non‐specific brain disorder characterized by a common set of signs and symptoms, usually arises subsequent to brain injuries or diseases and is often associated with the aging process. Individuals affected by dementia suffer from the disruption of several neurotransmitter and neuromodulatory systems, among which neurolipids play an important role, including the endocannabinoid, lysophosphatidic acid and sphingosine 1‐phosphate systems. In this review, we present an overview of the most recent and pertinent findings regarding the involvement of these neurolipidic systems in dementia, including data from a wide range of both in vitro and in vivo experiments as well as clinical trials.

The Elusive Truth of Cannabinoids for Rheumatic Pain

PURPOSE OF REVIEW

Medical cannabis (MC) has entered mainstream medicine by a unique route. Regulatory acceptance as a medical product in many jurisdictions has bypassed the traditional evidence-based pathway required for therapies. Easier access to MC, especially related to recreational legalization of cannabis, has led to widespread use by patients for symptom relief of a variety of medical conditions and often without medical oversight. Musculoskeletal pain remains the most common reason for MC use. This review examines real-world issues pertaining to MC and offers some guidance for clinical care of patients with rheumatic diseases being treated with MC.

RECENT FINDINGS

Controlled clinical studies of cannabis products in patients with rheumatic diseases have been small and tested a range of compounds, routes of administration, and clinical populations, limiting our ability to generate conclusions on MC's effectiveness in this population. Observational cohort studies and surveys suggest that use of MC and related products in patients with rheumatic diseases improves pain and associated symptoms but is commonly accompanied by mild to moderate side effects. Conflicting evidence contributes to practitioner and patient uncertainty regarding the use of MC for rheumatic disease-related pain. Despite promising preclinical and observational evidence that MC and cannabis-derived compounds are useful in the management of rheumatic disease-related pain, there remains limited high-quality clinical evidence to substantiate these findings. There are a significant number of clinical trials on this topic currently planned or underway, however, suggesting the next decade may yield more clarity. Nevertheless, given that many people with rheumatic diseases are using cannabis products, healthcare professionals must remain apprised of the evidence pertaining to cannabinoids, communicate such evidence to patients in a meaningful way that is free from personal bias and stigma, and maintain strong collaborative clinical care pertaining to MC.

The changing metabolic landscape of bile acids - keys to metabolism and immune regulation

Bile acids regulate nutrient absorption and mitochondrial function, they establish and maintain gut microbial community composition and mediate inflammation, and they serve as signalling molecules that regulate appetite and energy homeostasis. The observation that there are hundreds of bile acids, especially many amidated bile acids, necessitates a revision of many of the classical descriptions of bile acids and bile acid enzyme functions. For example, bile salt hydrolases also have transferase activity. There are now hundreds of known modifications to bile acids and thousands of bile acid-associated genes, especially when including the microbiome, distributed throughout the human body (for example, there are >2,400 bile salt hydrolases alone). The fact that so much of our genetic and small-molecule repertoire, in both amount and diversity, is dedicated to bile acid function highlights the centrality of bile acids as key regulators of metabolism and immune homeostasis, which is, in large part, communicated via the gut microbiome.

Cannabinoids' Role in Modulating Central and Peripheral Immunity in Neurodegenerative Diseases

Cannabinoids (the endocannabinoids, the synthetic cannabinoids, and the phytocannabinoids) are well known for their various pharmacological properties, including neuroprotective and anti-inflammatory features, which are fundamentally important for the treatment of neurodegenerative diseases. The aging of the global population is causing an increase in these diseases that require the development of effective drugs to be even more urgent. Taking into account the unavailability of effective drugs for neurodegenerative diseases, it seems appropriate to consider the role of cannabinoids in the treatment of these diseases. To our knowledge, few reviews are devoted to cannabinoids' impact on modulating central and peripheral immunity in neurodegenerative diseases. The objective of this review is to provide the best possible information about the cannabinoid receptors and immuno-modulation features, peripheral immune modulation by cannabinoids, cannabinoid-based therapies for the treatment of neurological disorders, and the future development prospects of making cannabinoids versatile tools in the pursuit of effective drugs.

Cannabinoid Analgesia in Postoperative Pain Management: From Molecular Mechanisms to Clinical Reality

Postoperative pain (POP) is a challenging clinical phenomenon that affects the majority of surgical patients and demands effective management to mitigate adverse outcomes such as persistent pain. The primary goal of POP management is to alleviate suffering and facilitate a seamless return to normal function for the patient. Despite compelling evidence of its drawbacks, opioid analgesia remains the basis of POP treatment. Novel therapeutic approaches rely on multimodal analgesia, integrating different pharmacological strategies to optimize efficacy while minimizing adverse effects. The recognition of the imperative role of the endocannabinoid system in pain regulation has prompted the investigation of cannabinoid compounds as a new therapeutic avenue. Cannabinoids may serve as adjuvants, enhancing the analgesic effects of other drugs and potentially replacing or at least reducing the dependence on other long-term analgesics in pain management. This narrative review succinctly summarizes pertinent information on the molecular mechanisms, clinical therapeutic benefits, and considerations associated with the plausible use of various cannabinoid compounds in treating POP. According to the available evidence, cannabinoid compounds modulate specific molecular mechanisms intimately involved in POP. However, only two of the eleven clinical trials that evaluated the efficacy of different cannabinoid interventions showed positive results.

Herbal Cannabis and Depression: A Review of Findings Published over the Last Three Years

Public perception contrasts scientific findings on the depression-related effects of cannabis. However, earlier studies were performed when cannabis was predominantly illegal, its production was mostly uncontrolled, and the idea of medical cannabis was incipient only. We hypothesized that recent changes in attitudes and legislations may have favorably affected research. In addition, publication bias against cannabis may have also decreased. To investigate this hypothesis, we conducted a review of research studies published over the last three years. We found 156 relevant research articles. In most cross-sectional studies, depression was higher in those who consumed cannabis than in those who did not. An increase in cannabis consumption was typically followed by an increase in depression, whereas withdrawal from cannabis ameliorated depression in most cases. Although medical cannabis reduced depression in most studies, none of these were placebo-controlled. In clinical studies published in the same period, the placebo also ameliorated depression and, in addition, the average effect size of the placebo was larger than the average effect size of medical cannabis. We also investigated the plausibility of the antidepressant effects of cannabis by reviewing molecular and pharmacological studies. Taken together, the reviewed findings do not support the antidepressant effects of herbal cannabis.

Association between history of cannabis use and outcomes after total hip or knee arthroplasty: a systematic review and meta-analysis

Background

Cannabis use may be increasing as countries legalize it and it becomes socially acceptable. A history of cannabis use may increase risk of complications after various kinds of surgery and compromise functional recovery. Here we systematically reviewed and meta-analyzed available evidence on how history of cannabis use affects recovery after hip or knee arthroplasty (THA/TKA).

Methods

The PubMed, EMBASE, and Web of Science databases were comprehensively searched and studies were selected and analyzed in accordance with the PRISMA guidelines. The methodological quality of included studies was assessed based on the Newcastle-Ottawa Scale, while quality of evidence was evaluated according to the "Grading of recommendations assessment, development, and evaluation" system. Data on various outcomes were pooled when appropriate and meta-analyzed.

Results

The systematic review included 16 cohort studies involving 5.91 million patients. Meta-analysis linked history of cannabis use to higher risk of the following outcomes: revision (RR 1.68, 95% CI 1.31-2.16), mechanical loosening (RR 1.77, 95% CI 1.52-2.07), periprosthetic fracture (RR 1.85, 95% CI 1.38-2.48), dislocation (RR 2.10, 95% CI 1.18-3.73), cardiovascular events (RR 2.49, 95% CI 1.22-5.08), cerebrovascular events (RR 3.15, 95% CI 2.54-3.91), pneumonia (RR 3.97, 95% CI 3.49-4.51), respiratory failure (RR 4.10, 95% CI 3.38-4.97), urinary tract infection (RR 2.46, 95% CI 1.84-3.28), acute kidney injury (RR 3.25, 95% CI 2.94-3.60), venous thromboembolism (RR 1.48, 95% CI 1.34-1.63), and deep vein thrombosis (RR 1.42, 95% CI 1.19-1.70). In addition, cannabis use was associated with significantly greater risk of postoperative transfusion (RR 2.23, 95% CI 1.83-2.71) as well as higher hospitalization costs.

Conclusion

History of cannabis use significantly increases the risk of numerous complications and transfusion after THA or TKA, leading to greater healthcare costs. Clinicians should consider these factors when treating cannabis users, and pre-surgical protocols should give special consideration to patients with history of cannbis use.

Cannabinoid and Orexigenic Systems Interplay as a New Focus of Research in Alzheimer's Disease

Alzheimer's disease (AD) remains a significant health challenge, with an increasing prevalence globally. Recent research has aimed to deepen the understanding of the disease pathophysiology and to find potential therapeutic interventions. In this regard, G protein-coupled receptors (GPCRs) have emerged as novel potential therapeutic targets to palliate the progression of neurodegenerative diseases such as AD. Orexin and cannabinoid receptors are GPCRs capable of forming heteromeric complexes with a relevant role in the development of this disease. On the one hand, the hyperactivation of the orexins system has been associated with sleep-wake cycle disruption and Aβ peptide accumulation. On the other hand, cannabinoid receptor overexpression takes place in a neuroinflammatory environment, favoring neuroprotective effects. Considering the high number of interactions between cannabinoid and orexin systems that have been described, regulation of this interplay emerges as a new focus of research. In fact, in microglial primary cultures of APPSw/Ind mice model of AD there is an important increase in CB2R-OX1R complex expression, while OX1R antagonism potentiates the neuroprotective effects of CB2R. Specifically, pretreatment with the OX1R antagonist has been shown to strongly potentiate CB2R signaling in the cAMP pathway. Furthermore, the blockade of OX1R can also abolish the detrimental effects of OX1R overactivation in AD. In this sense, CB2R-OX1R becomes a new potential therapeutic target to combat AD.

Cannabis Science and Therapeutics: An Overview for Clinicians

Cannabis-based therapeutics have garnered increasing attention in recent years as patients seek alternative treatments for various medical conditions. This narrative review provides a comprehensive overview of the science behind the medical use of cannabis, focusing on the medical evidence for commonly treated conditions. In addition, the review addresses the practical considerations of using cannabis as a therapeutic agent, offering insights into dosing strategies, variations in cannabinoid formulation, and individual patient responses. Precautions, adverse consequences, and drug interactions are also discussed, with a focus on patient safety and the potential risks associated with cannabis use.

CBD in the Treatment of Epilepsy

It has been several years since highly purified cannabidiol (CBD) was registered as a medication that can be used in children of at least 2 years of age to treat different types of seizures related to Lennox-Gastaut syndrome (LGS), Dravet syndrome (DS), and more recently tuberous sclerosis complex (TSC). During this time, 39 randomized clinical trials (RCTs) and 13 meta-analyses on the efficacy and safety of CBD treatment have been published. Each of the meta-analyses had its own criteria for the RCTs' inclusion and, therefore, slightly different interpretations of the analyzed data. Each of them contributed in its own way to the understanding of CBD pharmacology, mechanisms of therapeutic action, development of adverse reactions, and drug-drug interactions. Hence, it seemed reasonable to gather the most relevant data in one article and present all the current knowledge on the use of CBD in epilepsy. The results of the 13 meta-analyses presented herein confirmed the effectiveness and safety of CBD in children and adolescents with DREs. In adults, reliable conclusions cannot be drawn due to insufficient data.

The Interaction of the Endocannabinoid Anandamide and Paracannabinoid Lysophosphatidylinositol during Cell Death Induction in Human Breast Cancer Cells

Endocannabinoid anandamide (AEA) and paracannabinoid lysophosphatidylinositol (LPI) play a significant role in cancer cell proliferation regulation. While anandamide inhibits the proliferation of cancer cells, LPI is known as a cancer stimulant. Despite the known endocannabinoid receptor crosstalk and simultaneous presence in the cancer microenvironment of both molecules, their combined activity has never been studied. We evaluated the effect of LPI on the AEA activity in six human breast cancer cell lines of different carcinogenicity (MCF-10A, MCF-7, BT-474, BT-20, SK-BR-3, MDA-MB-231) using resazurin and LDH tests after a 72 h incubation. AEA exerted both anti-proliferative and cytotoxic activity with EC50 in the range from 31 to 80 µM. LPI did not significantly affect the cell viability. Depending on the cell line, the response to the LPI-AEA combination varied from a decrease in AEA cytotoxicity to an increase in it. Based on the inhibitor analysis of the endocannabinoid receptor panel, we showed that for the former effect, an active GPR18 receptor was required and for the latter, an active CB2 receptor. The data obtained for the first time are important for the understanding the manner by which endocannabinoid receptor ligands acting simultaneously can modulate cancer growth at different stages.

A GraphSAGE-based model with fingerprints only to predict drug-drug interactions

Drugs are an effective way to treat various diseases. Some diseases are so complicated that the effect of a single drug for such diseases is limited, which has led to the emergence of combination drug therapy. The use multiple drugs to treat these diseases can improve the drug efficacy, but it can also bring adverse effects. Thus, it is essential to determine drug-drug interactions (DDIs). Recently, deep learning algorithms have become popular to design DDI prediction models. However, most deep learning-based models need several types of drug properties, inducing the application problems for drugs without these properties. In this study, a new deep learning-based model was designed to predict DDIs. For wide applications, drugs were first represented by commonly used properties, referred to as fingerprint features. Then, these features were perfectly fused with the drug interaction network by a type of graph convolutional network method, GraphSAGE, yielding high-level drug features. The inner product was adopted to score the strength of drug pairs. The model was evaluated by 10-fold cross-validation, resulting in an AUROC of 0.9704 and AUPR of 0.9727. Such performance was better than the previous model which directly used drug fingerprint features and was competitive compared with some other previous models that used more drug properties. Furthermore, the ablation tests indicated the importance of the main parts of the model, and we analyzed the strengths and limitations of a model for drugs with different degrees in the network. This model identified some novel DDIs that may bring expected benefits, such as the combination of PEA and cannabinol that may produce better effects. DDIs that may cause unexpected side effects have also been discovered, such as the combined use of WIN 55,212-2 and cannabinol. These DDIs can provide novel insights for treating complex diseases or avoiding adverse drug events.

Advances in steroid research from the pioneering neurosteroid concept to metabolomics: New insights into pregnenolone function

Advances in neuroendocrinology have led to major discoveries since the 19th century, identifying adaptive loops for maintaining homeostasis. One of the most remarkable discoveries was the concept of neurosteroids, according to which the brain is not only a target but also a source of steroid production. The identification of new membrane steroid targets now underpins the neuromodulatory effects of neurosteroids such as pregnenolone, which is involved in functions mediated by the GPCR CB1 receptor. Structural analysis of steroids is a key feature of their interactions with the phospholipid membrane, receptors and resulting activity. Therefore, mass spectrometry-based methods have been developed to elucidate the metabolic pathways of steroids, the ultimate approach being metabolomics, which allows the identification of a large number of metabolites in a single sample. This approach should enable us to make progress in understanding the role of neurosteroids in the functioning of physiological and pathological processes.

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

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

Anxiety Modulation by Cannabinoids-The Role of Stress Responses and Coping

Endocannabinoids were implicated in a variety of pathological conditions including anxiety and are considered promising new targets for anxiolytic drug development. The optimism concerning the potentials of this system for anxiolysis is probably justified. However, the complexity of the mechanisms affected by endocannabinoids, and discrepant findings obtained with various experimental approaches makes the interpretation of research results difficult. Here, we review the anxiety-related effects of the three main interventions used to study the endocannabinoid system: pharmacological agents active at endocannabinoid-binding sites present on both the cell membrane and in the cytoplasm, genetic manipulations targeting cannabinoid receptors, and function-enhancers represented by inhibitors of endocannabinoid degradation and transport. Binding-site ligands provide inconsistent findings probably because they activate a multitude of mechanisms concomitantly. More robust findings were obtained with genetic manipulations and particularly with function enhancers, which heighten ongoing endocannabinoid activation rather than affecting all mechanisms indiscriminately. The enhancement of ongoing activity appears to ameliorate stress-induced anxiety without consistent effects on anxiety in general. Limited evidence suggests that this effect is achieved by promoting active coping styles in critical situations. These findings suggest that the functional enhancement of endocannabinoid signaling is a promising drug development target for stress-related anxiety disorders.

Cannabis sativa: origin and history, glandular trichome development, and cannabinoid biosynthesis

Is Cannabis a boon or bane? Cannabis sativa has long been a versatile crop for fiber extraction (industrial hemp), traditional Chinese medicine (hemp seeds), and recreational drugs (marijuana). Cannabis faced global prohibition in the twentieth century because of the psychoactive properties of ∆9-tetrahydrocannabinol; however, recently, the perspective has changed with the recognition of additional therapeutic values, particularly the pharmacological potential of cannabidiol. A comprehensive understanding of the underlying mechanism of cannabinoid biosynthesis is necessary to cultivate and promote globally the medicinal application of Cannabis resources. Here, we comprehensively review the historical usage of Cannabis, biosynthesis of trichome-specific cannabinoids, regulatory network of trichome development, and synthetic biology of cannabinoids. This review provides valuable insights into the efficient biosynthesis and green production of cannabinoids, and the development and utilization of novel Cannabis varieties.

Endocannabinoid basis of personality-Insights from animal model of social behavior

Rationale: The endocannabinoid system is known to be involved in learning, memory, emotional processing and regulation of personality patterns. Here we assessed the endocannabinoid profile in the brains of mice with strong characteristics of social dominance and submissiveness. Methods: A lipidomics approach was employed to assess the endocannabinoidome in the brains of Dominant (Dom) and Submissive (Sub) mice. The endocannabinoid showing the greatest difference in concentration in the brain between the groups, docosatetraenoyl ethanolamine (DEA), was synthesized, and its effects on the physiological and behavioral responses of Dom and Sub mice were evaluated. mRNA expression of the endocannabinoid receptors and enzymes involved in PUFA biosynthesis was assessed using qRT-PCR. Results: Targeted LC/MS analysis revealed that long-chain polyunsaturated ethanolamides including arachidonoyl ethanolamide (AEA), DEA, docosatrienoyl ethanolamide (DTEA), eicosatrienoyl ethanolamide (ETEA), eicosapentaenoyl ethanolamide (EPEA) and docosahexaenoyl ethanolamide (DHEA) were higher in the Sub compared with the Dom mice. Untargeted LC/MS analysis showed that the parent fatty acids, docosatetraenoic (DA) and eicosapentaenoic (EPA), were higher in Sub vs. Dom. Gene expression analysis revealed increased mRNA expression of genes encoding the desaturase FADS2 and the elongase ELOVL5 in Sub mice compared with Dom mice. Acute DEA administration at the dose of 15 mg/kg produced antinociceptive and locomotion-inducing effects in Sub mice, but not in Dom mice. Subchronic treatment with DEA at the dose of 5 mg/kg augmented dominant behavior in wild-type ICR and Dom mice but not in Sub mice. Conclusion: This study suggests that the endocannabinoid system may play a role in the regulation of dominance and submissiveness, functional elements of social behavior and personality. While currently we have only scratched the surface, understanding the role of the endocannabinoid system in personality may help in revealing the mechanisms underlying the etiopathology of psychiatric disorders.