Rapid broad-spectrum analgesia through activation of peroxisome proliferator-activated receptor-alpha

Chronic Visceral Pain: New Peripheral Mechanistic Insights and Resulting Treatments

Chronic visceral pain is one of the most common reasons for patients with gastrointestinal disorders, such as inflammatory bowel disease or disorders of brain-gut interaction, to seek medical attention. It represents a substantial burden to patients and is associated with anxiety, depression, reductions in quality of life, and impaired social functioning, as well as increased direct and indirect health care costs to society. Unfortunately, the diagnosis and treatment of chronic visceral pain is difficult, in part because our understanding of the underlying pathophysiologic basis is incomplete. In this review, we highlight recent advances in peripheral pain signaling and specific physiologic and pathophysiologic preclinical mechanisms that result in the sensitization of peripheral pain pathways. We focus on preclinical mechanisms that have been translated into treatment approaches and summarize the current evidence base for directing treatment toward these mechanisms of chronic visceral pain derived from clinical trials. The effective management of chronic visceral pain remains of critical importance for the quality of life of suffers. A deeper understanding of peripheral pain mechanisms is necessary and may provide the basis for novel therapeutic interventions.

Efficacy of Topical Palmitoylethanolamide (Levagen+) for the Management of Eczema Symptoms: A Double-Blind, Comparator-Controlled, Randomized Clinical Trial

INTRODUCTION

Eczema is a debilitating skin disorder clinically characterised by the development of itchy, dry, rough, and scaling skin caused by a series of rudimentary clinical phenotypes.

METHODS

This double-blind, randomised, comparator-controlled trial evaluated the effectiveness of topical application of a novel palmitoylethanolamide formulation (Levagen+) compared with a standard moisturiser (comparator) to reduce eczema severity and improve patient outcomes. Seventy-two participants aged over 18 years old with atopic eczema (symptoms including redness, dry skin, scaling, and/or itchiness) on their hands or arm were recruited. Participants were randomly allocated to one of two treatment groups (Levagen + or comparator). Treatment was applied to the affected area twice daily for 4 weeks. Outcome measures included Self-Assessed Eczema Area Severity Index (SA-EASI) scoring and Patient-Oriented Eczema Measure (POEM) from baseline to week 4.

RESULTS

Levagen+ was effective at alleviating symptom severity of eczema over 4 weeks. Levagen+ significantly reduced redness, dryness, and total POEM score compared to a comparator cream.

CONCLUSION

Levagen+ can significantly reduce eczema symptom severity compared to a comparator product, supporting its use as a potential treatment for eczema.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT05003453.

NAAA-regulated lipid signaling in monocytes controls the induction of hyperalgesic priming in mice

Circulating monocytes participate in pain chronification but the molecular events that cause their deployment are unclear. Using a mouse model of hyperalgesic priming (HP), we show that monocytes enable progression to pain chronicity through a mechanism that requires transient activation of the hydrolase, N-acylethanolamine acid amidase (NAAA), and the consequent suppression of NAAA-regulated lipid signaling at peroxisome proliferator-activated receptor-α (PPAR-α). Inhibiting NAAA in the 72 hours following administration of a priming stimulus prevented HP. This effect was phenocopied by NAAA deletion and depended on PPAR-α recruitment. Mice lacking NAAA in CD11b+ cells - monocytes, macrophages, and neutrophils - were resistant to HP induction. Conversely, mice overexpressing NAAA or lacking PPAR-α in the same cells were constitutively primed. Depletion of monocytes, but not resident macrophages, generated mice that were refractory to HP. The results identify NAAA-regulated signaling in monocytes as a control node in the induction of HP and, potentially, the transition to pain chronicity.

A Sensitive Ultrahigh-Performance Liquid Chromatography/Tandem Mass Spectrometry Method for the Simultaneous Analysis of Phytocannabinoids and Endocannabinoids in Plasma and Brain

Introduction: Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) are major chemical constituents of cannabis, which may interact either directly or indirectly with the endocannabinoid and endocannabinoid-like ("paracannabinoid") systems, two lipid-based signaling complexes that play important roles in physiology. Legislative changes emphasize the need to understand how THC and CBD might impact endocannabinoid and paracannabinoid signaling, and to develop analytical approaches to study such impact. In this study, we describe a sensitive and accurate method for the simultaneous quantification of THC, its main oxidative metabolites [11-hydroxy-Δ9-THC (11-OH-THC) and 11-nor-9-carboxy-Δ9-THC (11-COOH-THC)], CBD, and a representative set of endocannabinoid [anandamide and 2-arachidonoyl-sn-glycerol (2-AG)] and paracannabinoid [palmitoylethanolamide (PEA) and oleoylethanolamide (OEA)] compounds. Analyte separation relies on the temperature-dependent shape selectivity properties of polymerically bonded C18 stationary phases. Materials and Methods: Analytes are extracted from tissues using acetonitrile precipitation followed by phospholipid removal. The ultrahigh-performance liquid chromatography/tandem mass spectrometry protocol utilizes a commercially available C18 polymeric-bonded phase column and a simple gradient elution system. Results: Ten-point calibration curves show excellent linearity (R2>0.99) over a wide range of analyte concentrations (0.02-500 ng/mL). Lowest limits of quantification are 0.05 ng/mL for anandamide, 0.1 ng/mL for 11-OH-THC and OEA, 0.2 ng/mL for THC and CBD, 0.5 ng/mL for 11-COOH-THC, 1.0 ng/mL for 2-AG, and 2.0 ng/mL for PEA. The lowest limits of detection are 0.02 ng/mL for anandamide, 0.05 ng/mL for 11-OH-THC and OEA, 0.1 ng/mL for THC and CBD, 0.2 ng/mL for 11-COOH-THC, 0.5 ng/mL for 2-AG, and 1.0 ng/mL for PEA. Conclusions: An application of the method is presented, which showed that phytocannabinoid administration elevates endocannabinoid levels in plasma and brain of adolescent male and female mice.

N-palmitoylethanolamide synergizes the antinociception of morphine and gabapentin in the formalin test in mice

OBJECTIVE

The antinociceptive pharmacological interaction between N-palmitoylethanolamide (PEA) and morphine (MOR), as well as gabapentin (GBP), was investigated to obtain synergistic antinociception at doses where side effects were minimal. In addition, the possible antinociceptive mechanism of PEA + MOR or PEA + GBP combinations was explored.

METHODS

Individual dose-response curves (DRCs) of PEA, MOR and GBP were evaluated in female mice in which intraplantar nociception was induced with 2% formalin. Isobolographic method was used to detect the pharmacological interaction in the combination of PEA + MOR or PEA + GBP.

KEY FINDINGS

The ED50 was calculated from the DRC; the order of potency was MOR > PEA > GBP. The isobolographic analysis was obtained at a 1:1 ratio to determine the pharmacological interaction. The experimental values of flinching (PEA + MOR, Zexp = 2.72 ± 0.2 μg/paw and PEA + GBP Zexp = 2.77 ± 0.19 μg/paw) were significantly lower than those calculated theoretically (PEA + MOR Zadd = 7.78 ± 1.07 and PEA + GBP Zadd = 24.05 ± 1.91 μg/paw), resulting in synergistic antinociception. Pretreatment with GW6471 and naloxone demonstrated that peroxisome proliferator-activated receptor alpha (PPARα) and opioid receptors are involved in both interactions.

CONCLUSIONS

These results suggest that MOR and GBP synergistically enhance PEA-induced antinociception through PPARα and opioid receptor mechanisms. Furthermore, the results suggest that combinations containing PEA with MOR or GBP could be of interest in aiding the treatment of inflammatory pain.

Cannabinoids And Cannabinoid-Like Compounds: Biochemical Characterization And Pharmacological Perspectives

Publication interest in cannabinoids, including phytocannabinoids, endogenous cannabinoids, synthetic cannabinoids and cannabinomimetic compounds, is due to the therapeutic potential of these compounds in inflammatory pathology. Since recent years, scientific interest was focused on compounds with cannabinomimetic activity. The therapeutic use of phytocannabinoids and endocannabinoids is somewhat limited due to unresolved issues of dosing, toxicity and safety in humans, while cannabinoid-like compounds combine similar therapeutic effects with a high confirmed safety. Targets for endocannabinoids and phytocannabinoids are endocannabinoid receptors 1 and 2, G protein-coupled receptors (GPCRs), peroxisome proliferator-activated receptors (PPARs), and transient receptor potential ion channels (TRPs). Non-endocannabinoid N-acylethanolamines do not interact with cannabinoid receptors and exhibit agonist activity towards non-cannabinoid receptors, such as PPARs, GPCRs and TRPs. This literature review includes contemporary information on the biological activity, metabolism and pharmacological properties of cannabinoids and cannabinoid-like compounds, as well as their receptors. We established that only a few studies were devoted to the relationship of non-endocannabinoid N-acylethanolamines with non-cannabinoid receptors, such as PPARs, GPCRs, and also with TRPs. We have focused on issues that were insufficiently covered in the published sources in order to identify gaps in existing knowledge and determine the prospects for scientific research.

Distribution of an analgesic palmitoylethanolamide and other N-acylethanolamines in human placental membranes

BACKGROUND

Human amniotic and amniochorionic membranes (AM, ACM) represent the most often used grafts accelerating wound healing. Palmitoylethanolamide, oleoylethanolamide and anandamide are endogenous bioactive lipid molecules, generally referred as N-acylethanolamines. They express analgesic, nociceptive, neuroprotective and anti-inflammatory properties. We assessed the distribution of these lipid mediators in placental tissues, as they could participate on analgesic and wound healing effect of AM/ACM grafts.

METHODS

Seven placentas were collected after caesarean delivery and fresh samples of AM, ACM, placental disc, umbilical cord, umbilical serum and vernix caseosa, and decontaminated samples (antibiotic solution BASE 128) of AM and ACM have been prepared. Ultra-high-performance liquid chromatography-tandem mass spectrometry was used for N-acylethanolamines analysis.

RESULTS

N-acylethanolamines were present in all studied tissues, palmitoylethanolamide being the most abundant and the anandamide the least. For palmitoylethanolamide the maximum average concentration was detected in AM (350.33 ± 239.26 ng/g), while oleoylethanolamide and anandamide were most abundant in placenta (219.08 ± 79.42 ng/g and 30.06 ± 7.77 ng/g, respectively). Low levels of N-acylethanolamines were found in serum and vernix. A significant increase in the levels of N-acylethanolamines (3.1-3.6-fold, P < 0.001) was observed in AM when the tissues were decontaminated using antibiotic solution. The increase in decontaminated ACM was not statistically significant.

CONCLUSIONS

The presence of N-acylethanolamines, particularly palmitoylethanolamide in AM and ACM allows us to propose these lipid mediators as the likely factors responsible for the anti-hyperalgesic, but also anti-inflammatory and neuroprotective, effects of AM/ACM grafts in wound healing treatment. The increase of N-acylethanolamines levels in AM and ACM after tissue decontamination indicates that tissue processing is an important factor in maintaining the analgesic effect.

Palmitoylethanolamide and Related ALIAmides for Small Animal Health: State of the Art

ALIAmides are a family of fatty acid amides whose name comes from their mechanism of action, i.e., the Autacoid Local Injury Antagonism (ALIA). Actually, the ALIAmide parent molecule, palmitoylethanolamide (PEA), is locally produced on demand from a cell membrane precursor in order to control immune-inflammatory cell responses, avert chronic non-resolving inflammation, and limit the resulting clinical signs. ALIAmide sister compounds, such as Adelmidrol and palmitoylglucosamine, share mechanisms of action with PEA and may also increase endogenous levels of PEA. Provided that their respective bioavailability is properly addressed (e.g., through decreasing the particle size through micronization), exogenously administered ALIAmides thus mimic or sustain the prohomeostatic functions of endogenous PEA. The aim of the present paper is to review the main findings on the use of ALIAmides in small animals as a tribute to the man of vision who first believed in this “according-to-nature” approach, namely Francesco della Valle. After briefly presenting some key issues on the molecular targets, metabolism, and pharmacokinetics of PEA and related ALIAmides, here we will focus on the preclinical and clinical studies performed in dogs and cats. Although more data are still needed, ALIAmides may represent a novel and promising approach to small animal health.

Synergistic antinociceptive effects of concomitant NAAA and peripheral FAAH inhibition

The intracellular lipid amidases, fatty acid amide hydrolase (FAAH) and N-acylethanolamine acid amidase (NAAA), terminate the actions of anandamide and palmitoylethanolamide (PEA), two antinociceptive and anti-inflammatory lipid-derived mediators. Here we show, confirming prior research, that small-molecule inhibitors of peripheral FAAH (compound URB937) and systemic NAAA (compound ARN19702) individually attenuate, in male CD-1 mice, pain-related behaviors and paw inflammation in the formalin and carrageenan tests. More importantly, isobolographic analyses revealed that the combination of URB937 and ARN19702 produced substantial synergistic (greater than additive) antinociceptive effects in both models as well as additive anti-inflammatory effects in the carrageenan test. Together, the findings uncover a functional interplay between FAAH and NAAA substrates in the control of nociception, which might be exploited clinically to develop safe and effective pain management strategies.

Potentiation of endocannabinoids and other lipid amides prevents hyperalgesia and inflammation in a pre-clinical model of migraine

Targeting fatty acid amide hydrolase (FAAH) is a promising therapeutic strategy to combat certain forms of pain, including migraine headache. FAAH inhibitors, such as the O-biphenyl-3-yl carbamate URB597, have been shown to produce anti-hyperalgesic effects in animal models of migraine. The objective of this study was to investigate the behavioral and biochemical effects of compounds ARN14633 and ARN14280, two URB597 analogs with improved solubility and bioavailability, in a migraine-specific rat model in which trigeminal hyperalgesia is induced by nitroglycerin (NTG) administration. ARN14633 (1 mg/kg, i.p.) and ARN14280 (3 mg/kg, i.p.) were administered to adult male Sprague-Dawley rats 3 hours after NTG injection. One hour after the administration of either compound, rats were subjected to the orofacial formalin test. ARN14633 and ARN14280 attenuated NTG-induced nocifensive behavior and reduced transcription of genes encoding neuronal nitric oxide synthase, pain mediators peptides (calcitonin gene-related peptide, substance P) and pro-inflammatory cytokines (tumor necrosis factor-alpha, interleukin-1beta and 6) in the trigeminal ganglion, cervical spinal cord and medulla. Finally, both compounds strongly elevated levels of endocannabinoids and/or other FAAH substrates in cervical spinal cord and medulla, and, to a lesser extent, in the trigeminal ganglia. The results indicate that the novel global FAAH inhibitors ARN14633 and ARN14280 elicit significant anti-hyperalgesic effects in a migraine-specific animal model and inhibit the associated peptidergic-inflammatory response. Although the precise mechanism underlying these effects remains to be elucidated, our results support further investigational studies of FAAH blockade as a potential therapeutic strategy to treat migraine conditions.

Novel role of peroxisome proliferator activated receptor-α in valproic acid rat model of autism: Mechanistic study of risperidone and metformin monotherapy versus combination

Autism spectrum disorder (ASD) is a neurodevelopmental disorder of heterogenous etiology exhibiting a challenge in understanding its exact neuro-pathophysiology. Recently, peroxisome proliferator activated receptor (PPAR)-α activation was found to play a fundamental role in neuroprotection and improving autistic-like-behaviors in experimental animal models of ASD through alleviating neuroinflammation, oxidative-stress, astrocyte reactivity, tauopathy in addition to its favorable role in metabolic regulation, thus attracting attention as a possible target in treatment of ASD. This study aimed to investigate the role of PPAR-α, astrocytic dysfunction and tauopathy in ASD and detect the possible neuroprotective effects of metformin (MET), through PPAR-α activation, and risperidone (RIS) either monotherapy or in combination in alleviating autistic-like-changes at behavioral and neurobiological levels in male Wistar rats. Pregnant female Wistar rats received valproic-acid (VPA) to induce autistic-like-behavioral and neurobiological alterations in their offspring. Chronic intra-peritoneal MET (100 mg/kg/day) and RIS (1 mg/kg/day) either monotherapy or in combination started from postnatal day (PND) 24 till PND61 (38 days). Prenatal VPA exposure simulated the autistic core behaviors associated with neurochemical and histopathological neurodevelopmental degenerative changes. Both MET and RIS either monotherapy or in combination were able to reverse these changes. The effect of MET was comparable to RIS. Moreover, MET was able to alleviate the RIS induced weight gain and improve cognitive functions highlighting its promising adjunctive role in alleviating ASD pathophysiology. Our study highlighted the favorable effects of MET and RIS both in monotherapy and in combination in alleviating the autistic-like-changes and proposed PPAR-α activation along with restoring astrocytes homeostasis as promising targets in novel therapeutic strategies in ASD.

FABP5 deletion in nociceptors augments endocannabinoid signaling and suppresses TRPV1 sensitization and inflammatory pain

The endocannabinoid anandamide (AEA) produces antinociceptive effects by activating cannabinoid receptor 1 (CB1). However, AEA also serves as an agonist at transient receptor potential vanilloid receptor 1 (TRPV1) in nociceptive sensory neurons, which may exacerbate pain. This potential functional duality is highlighted by the failure of an inhibitor of the AEA catabolic enzyme fatty acid amide hydrolase (FAAH) to afford pain relief in a clinical trial. Consequently, it remains to be determined whether elevating AEA levels in nociceptors leads to antinociceptive or pro-nociceptive effects. Fatty acid binding protein 5 (FABP5) is an intracellular carrier that mediates AEA transport to FAAH for inactivation. Leveraging the abundant expression of FABP5 in TRPV1+ nociceptors, we employed a conditional knockout strategy to demonstrate that FABP5 deletion in nociceptors augments AEA levels, resulting in the emergence of antinociceptive effects mediated by CB1. Mechanistically, FABP5 deletion suppresses inflammation- and nerve growth factor-mediated TRPV1 sensitization via CB1, an effect mediated by calcineurin. Unexpectedly, inhibition of FAAH failed to blunt TRPV1 sensitization, uncovering functionally distinct outputs resulting from FABP5 and FAAH inhibition. Collectively, our results demonstrate that FABP5 serves a key role in governing endocannabinoid signaling in nociceptors to disrupt TRPV1 sensitization and pain, and position FABP5 as a therapeutic target for the development of analgesics.

Classical and Unexpected Effects of Ultra-Micronized PEA in Neuromuscular Function

Recently, the endocannabinoid system has attracted growing attention from the scientific community for its involvement in homeostatic and pathological processes as they pertains to human physiology. Among the constituents of the endocannabinoid system, the molecule palmitoyl ethanolamide has particularly been studied for its ability to reduce several inflammatory processes involving the central nervous system. Here, we reviewed published literature and summarized the main targets of the palmitoyl ethanolamide, along with its unique possible mechanisms for restoring correct functioning of the central nervous system. Moreover, we have highlighted a less-known characteristic of palmitoyl ethanolamide, namely its ability to modulate the function of the neuromuscular junction by binding to acetylcholine receptors in different experimental conditions. Indeed, there are several studies that have highlighted how ultra-micronized palmitoyl ethanolamide is an interesting nutraceutical support for the treatment of pathological neuromuscular conditions, specifically when the normal activity of the acetylcholine receptor is altered. Although further multicentric clinical trials are needed to confirm the efficacy of ultra-micronized palmitoyl ethanolamide in improving symptoms of neuromuscular diseases, all the literature reviewed here strongly supports the ability of this endocannabinoid-like molecule to modulate the acetylcholine receptors thus resulting as a valid support for the treatment of human neuromuscular diseases.

Effects of Ultramicronized Palmitoylethanolamide on Mitochondrial Bioenergetics, Cerebral Metabolism, and Glutamatergic Transmission: An Integrated Approach in a Triple Transgenic Mouse Model of Alzheimer's Disease

The therapeutic potential of ultramicronized palmitoylethanolamide (um-PEA) was investigated in young (6-month-old) and adult (12-month-old) 3 × Tg-AD mice, which received um-PEA for 3 months via a subcutaneous delivery system. Mitochondrial bioenergetics, ATP homeostasis, and magnetic resonance imaging/magnetic resonance spectroscopy were evaluated in the frontal cortex (FC) and hippocampus (HIPP) at the end of um-PEA treatment. Glutamate release was investigated by in vivo microdialysis in the ventral HIPP (vHIPP). We demonstrated that chronic um-PEA treatment ameliorates the decrease in the complex-I respiration rate and the FoF1-ATPase (complex V) activity, as well as ATP content depletion in the cortical mitochondria. Otherwise, the impairment in mitochondrial bioenergetics and the release of glutamate after depolarization was not ameliorated by um-PEA treatment in the HIPP of both young and adult 3 × Tg-AD mice. Moreover, progressive age- and pathology-related changes were observed in the cortical and hippocampal metabolism that closely mimic the alterations observed in the human AD brain; these metabolic alterations were not affected by chronic um-PEA treatment. These findings confirm that the HIPP is the most affected area by AD-like pathology and demonstrate that um-PEA counteracts mitochondrial dysfunctions and helps rescue brain energy metabolism in the FC, but not in the HIPP.

The endocannabinoid system and related lipids as potential targets for the treatment of migraine-related pain

BACKGROUND

Migraine is a complex and highly disabling neurological disease whose treatment remains challenging in many patients, even after the recent advent of the first specific-preventive drugs, namely monoclonal antibodies that target calcitonin gene-related peptide. For this reason, headache researchers are actively searching for new therapeutic targets. Cannabis has been proposed for migraine treatment, but controlled clinical studies are lacking. A major advance in cannabinoid research has been the discovery of the endocannabinoid system (ECS), which consists of receptors CB1 and CB2; their endogenous ligands, such as N-arachidonoylethanolamine; and the enzymes that catalyze endocannabinoid biosynthesis or degradation. Preclinical and clinical findings suggest a possible role for endocannabinoids and related lipids, such as palmitoylethanolamide (PEA), in migraine-related pain treatment. In animal models of migraine-related pain, endocannabinoid tone modulation via inhibition of endocannabinoid-catabolizing enzymes has been a particular focus of research.

METHODS

To conduct a narrative review of available data on the possible effects of cannabis, endocannabinoids, and other lipids in migraine-related pain, relevant key words were used to search the PubMed/MEDLINE database for basic and clinical studies.

RESULTS

Endocannabinoids and PEA seem to reduce trigeminal nociception by interacting with many pathways associated with migraine, suggesting a potential synergistic or similar effect.

CONCLUSIONS

Modulation of the metabolic pathways of the ECS may be a basis for new migraine treatments. The multiplicity of options and the wealth of data already obtained in animal models underscore the importance of further advancing research in this area. Multiple molecules related to the ECS or to allosteric modulation of CB1 receptors have emerged as potential therapeutic targets in migraine-related pain. The complexity of the ECS calls for accurate biochemical and pharmacological characterization of any new compounds undergoing testing and development.

Effects of Ultramicronized Palmitoylethanolamide (um-PEA) in COVID-19 Early Stages: A Case–Control Study

Ultramicronized palmitoylethanolamide (um-PEA), a compound with antioxidant, anti-inflammatory and neuroprotective properties, appears to be a potential adjuvant treatment for early stages of Coronavirus disease 2019 (COVID-19). In our study, we enrolled 90 patients with confirmed diagnosis of COVID-19 that were randomized into two groups, homogeneous for age, gender and BMI. The first group received oral supplementation based on um-PEA at a dose of 1800 mg/day for a total of 28 days; the second group was the control group (R.S. 73.20). At baseline (T0) and after 28 days of um-PEA treatment (T1), we monitored: routine laboratory parameters, inflammatory and oxidative stress (OS) biomarkers, lymphocytes subpopulation and COVID-19 serological response. At T1, the um-PEA-treated group presented a significant reduction in inflammation compared to the control group (CRP p = 0.007; IL-6 p = 0.0001; neutrophils to lymphocytes ratio p = 0.044). At T1, the controls showed a significant increase in OS compared to the treated group (FORT p = 0.05). At T1, the um-PEA group exhibited a significant decrease in D-dimer levels (p = 0.0001) and higher levels of IgG against SARS-CoV-2 (p = 0.0001) compared to the controls. Our data demonstrated, in a randomized clinical trial, the beneficial effects of um-PEA in both asymptomatic and mild-symptomatic patients related to reductions in inflammatory state, OS and coagulative cascade alterations.

Insights Into the Prognostic Value and Immunological Role of NAAA in Pan-Cancer

N-Acylethanolamine Acid Amidase (NAAA) is an N-terminal cysteine hydrolase and plays a vital physiological role in inflammatory response. However, the roles of NAAA in tumor immunity are still unclear. By using a series of bioinformatics approaches, we study combined data from different databases, including the Cancer Genome Atlas, the Cancer Cell Line Encyclopedia, Genotype Tissue-Expression, cBioPortal, Human Protein Atlas, TIMER, and ImmuCellAI to investigate the role of NAAA expression in prognosis and tumor immunity response. We would like to reveal the potential correlations between NAAA expression and gene alterations, tumor mutational burden (TMB), microsatellite instability (MSI), DNA methylation, tumor microenvironment (TME), immune infiltration levels, and various immune-related genes across different cancers. The results show that NAAA displayed abnormal expression within most malignant tumors, and overexpression of NAAA was associated with the poor prognosis of tumor patients. Through gene set enrichment analysis (GSEA), we found that NAAA was significantly associated with cell cycle and immune regulation-related signaling pathways, such as in innate immune system, adaptive immune system, neutrophil degranulation, and Toll-like receptor signaling pathways (TLRs). Further, the expression of NAAA was also confirmed to be correlated with tumor microenvironment and diverse infiltration of immune cells, especially tumor-associated macrophage (TAM). In addition to this, we found that NAAA is co-expressed with genes encoding major histocompatibility complex (MHC), immune activation, immune suppression, chemokine, and chemokine receptors. Meanwhile, we demonstrate that NAAA expression was correlated with TMB in 4 cancers and with MSI in 10 cancers. Our study reveals that NAAA plays an important role in tumorigenesis and cancer immunity, which may be used to function as a prognostic biomarker and potential target for cancer immunotherapy.

Palmitoylethanolamide: A Potential Alternative to Cannabidiol

The endocannabinoid system (ECS) is a widespread cell signaling network that maintains homeostasis in response to endogenous and exogenous stressors. This has made the ECS an attractive therapeutic target for various disease states. The ECS is a well-known target of exogenous phytocannabinoids derived from cannabis plants, the most well characterized being Δ⁹-tetrahydrocannabinol (THC) and cannabidiol (CBD). However, the therapeutic efficacy of cannabis products comes with a risk of toxicity and high abuse potential due to the psychoactivity of THC. CBD, on the other hand, is reported to have beneficial medicinal properties including analgesic, neuroprotective, anxiolytic, anticonvulsant, and antipsychotic activities, while apparently lacking the toxicity of THC. Nevertheless, not only is the currently available scientific data concerning CBD's efficacy insufficient, there is also ambiguity surrounding its regulatory status and safety in humans that brings inherent risks to manufacturers. There is a demand for alternative compounds combining similar effects with a robust safety profile and regulatory approval. Palmitoylethanolamide (PEA) is an endocannabinoid-like lipid mediator, primarily known for its anti-inflammatory, analgesic and neuroprotective properties. It appears to have a multi-modal mechanism of action, by primarily activating the nuclear receptor PPAR-α while also potentially working through the ECS, thus targeting similar pathways as CBD. With proven efficacy in several therapeutic areas, its safety and tolerability profile and the development of formulations that maximize its bioavailability, PEA is a promising alternative to CBD.

NAAA-regulated lipid signaling governs the transition from acute to chronic pain

Chronic pain affects 1.5 billion people worldwide but remains woefully undertreated. Understanding the molecular events leading to its emergence is necessary to discover disease-modifying therapies. Here we show that N-acylethanolamine acid amidase (NAAA) is a critical control point in the progression to pain chronicity, which can be effectively targeted by small-molecule therapeutics that inhibit this enzyme. NAAA catalyzes the deactivating hydrolysis of palmitoylethanolamide, a lipid-derived agonist of the transcriptional regulator of cellular metabolism, peroxisome proliferator-activated receptor-α (PPAR-α). Our results show that disabling NAAA in spinal cord during a 72-h time window following peripheral tissue injury halts chronic pain development in male and female mice by triggering a PPAR-α-dependent reprogramming of local core metabolism from aerobic glycolysis, which is transiently enhanced after end-organ damage, to mitochondrial respiration. The results identify NAAA as a crucial control node in the transition to chronic pain and a molecular target for disease-modifying medicines.

The Role of PPAR Alpha in the Modulation of Innate Immunity

Peroxisome proliferator-activated receptor α is a potent regulator of systemic and cellular metabolism and energy homeostasis, but it also suppresses various inflammatory reactions. In this review, we focus on its role in the regulation of innate immunity; in particular, we discuss the PPARα interplay with inflammatory transcription factor signaling, pattern-recognition receptor signaling, and the endocannabinoid system. We also present examples of the PPARα-specific immunomodulatory functions during parasitic, bacterial, and viral infections, as well as approach several issues associated with innate immunity processes, such as the production of reactive nitrogen and oxygen species, phagocytosis, and the effector functions of macrophages, innate lymphoid cells, and mast cells. The described phenomena encourage the application of endogenous and pharmacological PPARα agonists to alleviate the disorders of immunological background and the development of new solutions that engage PPARα activation or suppression.

Palmitoylethanolamide for sleep disturbance. A double-blind, randomised, placebo-controlled interventional study

Background

Sleep is essential for wellbeing, yet sleep disturbance is a common problem linked to a wide range of health conditions. Palmitoylethanolamide (PEA) is an endogenous fatty acid amide proposed to promote better sleep via potential interaction with the endocannabinoid system.

Methods

This double-blind, randomised study on 103 adults compared the efficacy and tolerability of 8 weeks of daily supplemented PEA formulation (350 mg Levagen + ®) to a placebo. Sleep quality and quantity were measured using wrist actigraphy, a sleep diary and questionnaires.

Results

At week 8, PEA supplementation reduced sleep onset latency, time to feel completely awake and improved cognition on waking. After 8 weeks, both groups improved their sleep quality and quantity scores similarly. There was no difference between groups at baseline or week 8 for sleep quantity or quality as measured from actigraphy or sleep diaries.

Conclusion

These findings support PEA as a potential sleeping aid capable of reducing sleep onset time and improving cognition on waking.

Trial registration

Australian New Zealand Clinical Trials Registry ACTRN12618001339246. Registered 9^th August 2018.

Different roles for the acyl chain and the amine leaving group in the substrate selectivity of N-Acylethanolamine acid amidase

N-acylethanolamine acid amidase (NAAA) is an N-terminal nucleophile (Ntn) hydrolase that catalyses the intracellular deactivation of the endogenous analgesic and anti-inflammatory agent palmitoylethanolamide (PEA). NAAA inhibitors counteract this process and exert marked therapeutic effects in animal models of pain, inflammation and neurodegeneration. While it is known that NAAA preferentially hydrolyses saturated fatty acid ethanolamides (FAEs), a detailed profile of the relationship between catalytic efficiency and fatty acid-chain length is still lacking. In this report, we combined enzymatic and molecular modelling approaches to determine the effects of acyl chain and polar head modifications on substrate recognition and hydrolysis by NAAA. The results show that, in both saturated and monounsaturated FAEs, the catalytic efficiency is strictly dependent upon fatty acyl chain length, whereas there is a wider tolerance for modifications of the polar heads. This relationship reflects the relative stability of enzyme-substrate complexes in molecular dynamics simulations.

Zerumbone Ameliorates Neuropathic Pain Symptoms via Cannabinoid and PPAR Receptors Using In Vivo and In Silico Models

Neuropathic pain is a chronic pain condition persisting past the presence of any noxious stimulus or inflammation. Zerumbone, of the Zingiber zerumbet ginger plant, has exhibited anti-allodynic and antihyperalgesic effects in a neuropathic pain animal model, amongst other pharmacological properties. This study was conducted to further elucidate the mechanisms underlying zerumbone's antineuropathic actions. Research on therapeutic agents involving cannabinoid (CB) and peroxisome proliferator-activated receptors (PPARs) is rising. These receptor systems have shown importance in causing a synergistic effect in suppressing nociceptive processing. Behavioural responses were assessed using the von Frey filament test (mechanical allodynia) and Hargreaves plantar test (thermal hyperalgesia), in chronic constriction injury (CCI) neuropathic pain mice. Antagonists SR141716 (CB1 receptor), SR144528 (CB2 receptor), GW6471 (PPARα receptor) and GW9662 (PPARγ receptor) were pre-administered before the zerumbone treatment. Our findings indicated the involvement of CB1, PPARα and PPARγ in zerumbone's action against mechanical allodynia, whereas only CB1 and PPARα were involved against thermal hyperalgesia. Molecular docking studies also suggest that zerumbone has a comparable and favourable binding affinity against the respective agonist on the CB and PPAR receptors studied. This finding will contribute to advance our knowledge on zerumbone and its significance in treating neuropathic pain.

Endocannabinoid Receptors in the CNS: Potential Drug Targets for the Prevention and Treatment of Neurologic and Psychiatric Disorders

The endocannabinoid system participates in the regulation of CNS homeostasis and functions, including neurotransmission, cell signaling, inflammation and oxidative stress, as well as neuronal and glial cell proliferation, differentiation, migration and survival. Endocannabinoids are produced by multiple cell types within the CNS and their main receptors, CB₁ and CB₂, are expressed in both neurons and glia. Signaling through these receptors is implicated in the modulation of neuronal and glial alterations in neuroinflammatory, neurodegenerative and psychiatric conditions, including Alzheimer’s, Parkinson’s and Huntington’s disease, multiple sclerosis, amyotrophic lateral sclerosis, stroke, epilepsy, anxiety and depression. The therapeutic potential of endocannabinoid receptors in neurological disease has been hindered by unwelcome side effects of current drugs used to target them; however, due to their extensive expression within the CNS and their involvement in physiological and pathological process in nervous tissue, they are attractive targets for drug development. The present review highlights the potential applications of the endocannabinoid system for the prevention and treatment of neurologic and psychiatric disorders.

PEA prevented early BBB disruption after cerebral ischaemic/reperfusion (I/R) injury through regulation of ROCK/MLC signaling

Palmitoylethanolamide (PEA) offers a strong protection against BBB disruption and neurological deficits after cerebral ischaemic/reperfusion (I/R) injury. To date, these BBB protective effects of PEA are mainly attributed to PPARα-mediated actions. However, whether PEA protects against BBB disruption through direct regulation of cytoskeletal microfilaments remains unknown. Here, we identified PEA as a Rho-associated protein kinase (ROCK2) inhibitor (IC₅₀ = 38.4 ± 4.8 μM). In vitro data suggested that PEA reduced the activation of ROCK/MLC signaling and stress fiber formation within microvascular endothelial cells (ECs) after oxygen-glucose deprivation (OGD), and consequently attenuated early (0-4 h) EC barrier disruption. These actions of PEA could not be blocked by the PPARα antagonist GW6471. In summary, the present study described a previously unexplored role of PEA as a ROCK2 inhibitor, and propose a PPARα-independent mechanism for pharmacological effects of PEA.

Pharmacological Blockade of PPARα Exacerbates Inflammatory Pain-Related Impairment of Spatial Memory in Rats

Peroxisome proliferator-activated receptors (PPARs) are ligand-dependent transcription factors that exist in three isoforms: PPARα, PPARβ/δ and PPARγ. Studies suggest that the PPAR signalling system may modulate pain, anxiety and cognition. The aim of the present study was to investigate whether endogenous signalling via PPARs differentially modulates innate anxiety responses and mnemonic function in the presence and absence of inflammatory pain. We examined the effects of intraperitoneal administration of GW6471 (PPARα antagonist), GSK0660 (PPARβ/δ antagonist), GW9662 (PPARγ antagonist), and N-palmitoylethanolamide (PEA) on rat behaviour in the elevated plus maze (EPM), open field (OF), light-dark box (LDB), and novel object recognition (NOR) tests in the presence or absence of chronic inflammatory pain. Complete Freund’s Adjuvant (CFA)-injected rats exhibited impaired recognition and spatial mnemonic performance in the NOR test and pharmacological blockade of PPARα further impaired spatial memory in CFA-treated rats. N-oleoylethanolamide (OEA) levels were higher in the dorsal hippocampus in CFA-injected animals compared to their counterparts. The results suggest a modulatory effect of CFA-induced chronic inflammatory pain on cognitive processing, but not on innate anxiety-related responses. Increased OEA-PPARα signalling may act as a compensatory mechanism to preserve spatial memory function following CFA injection.

Antinociceptive Profile of ARN19702, (2-Ethylsulfonylphenyl)-[(2S)-4-(6-fluoro-1,3-benzothiazol-2-yl)-2-methylpiperazin-1-yl]methanone, a Novel Orally Active N-Acylethanolamine Acid Amidase Inhibitor, in Animal Models

N-Acylethanolamine acid amidase (NAAA) is an N-terminal cysteine hydrolase that stops the physiologic actions of palmitoylethanolamide, an endogenous lipid messenger that activates the transcription factor, peroxisome proliferator-activated receptor-α We have previously reported that the compound ARN19702 [(2-ethylsulfonylphenyl)-[(2S)-4-(6-fluoro-1,3-benzothiazol-2-yl)-2-methylpiperazin-1-yl]methanone] is an orally active, reversible NAAA inhibitor (IC₅₀ on human NAAA = 230 nM) that produces remarkable protective effects against multiple sclerosis in mice. In the present study, we assessed the profile of ARN19702 in mouse and rat models of acute and neuropathic pain. Oral administration in male mice attenuated in a dose-dependent manner the spontaneous nocifensive response elicited by intraplantar formalin injection and the hypersensitivity caused by intraplantar carrageenan injection, paw incision, or sciatic nerve ligation. In male rats, ARN19702 reduced nociception associated with paclitaxel-induced neuropathy without development of subacute antinociceptive tolerance. Finally, ARN19702 (30 mg/kg, oral) did not produce place preference or alter exploratory motor behavior in male mice. The findings support the conclusion that NAAA is a suitable molecular target for the discovery of efficacious analgesic drugs devoid of rewarding potential. SIGNIFICANCE STATEMENT: This study evaluated the pharmacological profile of the orally bioavailable N-acylethanolamine acid amidase (NAAA) inhibitor (2-ethylsulfonylphenyl)-[(2S)-4-(6-fluoro-1,3-benzothiazol-2-yl)-2-methylpiperazin-1-yl]methanone (ARN19702) in mouse and rat models of neurogenic and inflammatory pain. The compound's potential rewarding and sedative effects were also examined. It is concluded that ARN19702 exhibits a broad analgesic profile that can be generalized across rodent species. The findings point to NAAA as a control node in the processing of neuropathic and inflammatory pain and to ARN19702 as a lead to uncover novel pain therapeutics devoid of addictive potential .

Chronic Pain in Dogs and Cats: Is There Place for Dietary Intervention with Micro-Palmitoylethanolamide?

The management of chronic pain is an integral challenge of small animal veterinary practitioners. Multiple pharmacological agents are usually employed to treat maladaptive pain including opiates, non-steroidal anti-inflammatory drugs, anticonvulsants, antidepressants, and others. In order to limit adverse effects and tolerance development, they are often combined with non-pharmacologic measures such as acupuncture and dietary interventions. Accumulating evidence suggests that non-neuronal cells such as mast cells and microglia play active roles in the pathogenesis of maladaptive pain. Accordingly, these cells are currently viewed as potential new targets for managing chronic pain. Palmitoylethanolamide is an endocannabinoid-like compound found in several food sources and considered a body's own analgesic. The receptor-dependent control of non-neuronal cells mediates the pain-relieving effect of palmitoylethanolamide. Accumulating evidence shows the anti-hyperalgesic effect of supplemented palmitoylethanolamide, especially in the micronized and co-micronized formulations (i.e., micro-palmitoylethanolamide), which allow for higher bioavailability. In the present paper, the role of non-neuronal cells in pain signaling is discussed and a large number of studies on the effect of palmitoylethanolamide in inflammatory and neuropathic chronic pain are reviewed. Overall, available evidence suggests that there is place for micro-palmitoylethanolamide in the dietary management of chronic pain in dogs and cats.

N-acylethanolamine-hydrolysing acid amidase: A new potential target to treat paclitaxel-induced neuropathy

BACKGROUND

Although paclitaxel is an effective chemotherapeutic agent used to treat multiple types of cancer (e.g. breast, ovarian, neck and lung), it also elicits paclitaxel-induced peripheral neuropathy (PIPN), which represents a major dose-limiting side effect of this drug.

METHODS

As the endogenously produced N-acylethanolamine, palmitoylethanolamide (PEA), reverses paclitaxel-induced mechanical hypersensitivity in mice, the main goals of this study were to examine if paclitaxel affects levels of endogenous PEA in the spinal cord of mice and whether exogenous administration of PEA provides protection from the occurrence of paclitaxel-induced mechanical hypersensitivity. We further examined whether inhibition of N-acylethanolamine-hydrolysing acid amidase (NAAA), a hydrolytic PEA enzyme, would offer protection in mouse model of PIPN.

RESULTS

Paclitaxel reduced PEA levels in the spinal cord, suggesting that dysregulation of this lipid signalling system may contribute to PIPN. Consistent with this idea, repeated administration of PEA partially prevented the paclitaxel-induced mechanical hypersensitivity. We next evaluated whether the selective NAAA inhibitor, AM9053, would prevent paclitaxel-induced mechanical hypersensitivity in mice. Acute administration of AM9053 dose-dependently reversed mechanical hypersensitivity through a PPAR-α mechanism, whereas repeated administration of AM9053 fully prevented the development of PIPN, without any evidence of tolerance. Moreover, AM9053 produced a conditioned place preference in paclitaxel-treated mice, but not in control mice. This pattern of findings suggests a lack of intrinsic rewarding effects, but a reduction in the pain aversiveness induced by paclitaxel. Finally, AM9053 did not alter paclitaxel-induced cytotoxicity in lung tumour cells.

CONCLUSIONS

Collectively, these studies suggest that NAAA represents a promising target to treat and prevent PIPN.

SIGNIFICANCE

The present study demonstrates that the chemotherapeutic paclitaxel alters PEA levels in the spinal cord, whereas repeated exogenous PEA administration moderately alleviates PIPN in mice. Additionally, targeting NAAA, PEA's hydrolysing enzyme with a selective compound AM9053 reverses and prevents the PIPN via the PPAR-α mechanism. Overall, the data suggest that selective NAAA inhibitors denote promising future therapeutics to mitigate and prevent PIPN.

Palmitoylethanolamide and hemp oil extract exert synergistic anti-nociceptive effects in mouse models of acute and chronic pain

The use of products derived from hemp - i.e., cannabis varieties with low Δ⁹-tetrahydrocannabinol (Δ⁹-THC) content - as self-medication for pain and other health conditions is gaining in popularity but preclinical and clinical evidence for their effectiveness remains very limited. In the present study, we assessed the efficacy of a full-spectrum hemp oil extract (HOE; 10, 50 and 100 mg-kg^-1; oral route), alone or in combination with the anti-inflammatory and analgesic agent palmitoylethanolamide (PEA; 10, 30, 100 and 300 mg-kg^-1; oral route), in the formalin and chronic constriction injury (CCI) tests. We found that HOE exerts modest antinociceptive effects when administered alone, whereas the combination of sub-effective oral doses of HOE and PEA produces a substantial greater-than-additive alleviation of pain-related behaviors. Transcription of interleukin (IL)-6 and IL-10 increased significantly in lumbar spinal cord tissue on day 7 after CCI surgery, an effect that was attenuated to the same extent by HOE alone or by the HOE/PEA combination. Pharmacokinetic experiments show that co-administration of HOE enhances and prolongs systemic exposure to PEA. Collectively, our studies lend support to possible beneficial effects of using HOE in combination with PEA to treat acute and chronic pain.

The Endocannabinoid System and PPARs: Focus on Their Signalling Crosstalk, Action and Transcriptional Regulation

Peroxisome proliferator-activated receptors (PPARs) are a family of nuclear receptors including PPARα, PPARγ, and PPARβ/δ, acting as transcription factors to regulate the expression of a plethora of target genes involved in metabolism, immune reaction, cell differentiation, and a variety of other cellular changes and adaptive responses. PPARs are activated by a large number of both endogenous and exogenous lipid molecules, including phyto- and endo-cannabinoids, as well as endocannabinoid-like compounds. In this view, they can be considered an extension of the endocannabinoid system. Besides being directly activated by cannabinoids, PPARs are also indirectly modulated by receptors and enzymes regulating the activity and metabolism of endocannabinoids, and, vice versa, the expression of these receptors and enzymes may be regulated by PPARs. In this review, we provide an overview of the crosstalk between cannabinoids and PPARs, and the importance of their reciprocal regulation and modulation by common ligands, including those belonging to the extended endocannabinoid system (or "endocannabinoidome") in the control of major physiological and pathophysiological functions.

Activation of dsRNA-Dependent Protein Kinase R by miR-378 Sustains Metabolic Inflammation in Hepatic Insulin Resistance

MicroRNAs (miRNAs) are noncoding small RNAs that regulate various pathophysiological cellular processes. Here, we report that expression of the miR-378 family was significantly induced by metabolic inflammatory inducers, a high-fructose diet, and inflammatory cytokine tumor necrosis factor-α. Hepatic miRNA profiling revealed that expression of miR-378a was highly upregulated, which, in turn, targeted the 3'-untranslated region of PPARα mRNA, impaired mitochondrial fatty acid β-oxidation, and induced mitochondrial and endoplasmic reticulum stress. More importantly, the upregulated miR-378a can directly bind to and activate the double-strand RNA (dsRNA)-dependent protein kinase R (PKR) to sustain the metabolic stress. In vivo, genetic depletion of miR-378a prevented PKR activation and ameliorated inflammatory stress and insulin resistance. Counterbalancing the upregulated miR-378a using nanoparticles encapsulated with an anti-miR-378a oligonucleotide restored PPARα activity, inhibited PKR activation and ER stress, and improved insulin sensitivity in fructose-fed mice. Our study delineated a novel mechanism of miR-378a in the pathogenesis of metabolic inflammation and insulin resistance through targeting metabolic signaling at both mRNA (e.g., PPARα) and protein (e.g., PKR) molecules. This novel finding of functional interaction between miRNAs (e.g., miR-378a) and cellular RNA binding proteins (e.g., PKR) is biologically significant because it greatly broadens the potential targets of miRNAs in cellular pathophysiological processes.

Targeting Peroxisome Proliferator-Activated Receptor-α (PPAR- α) to reduce paclitaxel-induced peripheral neuropathy

BACKGROUND AND PURPOSE

Paclitaxel, a widely used anti-cancer drug, is frequently associated with prolonged and severe peripheral neuropathies (PIPN), associated with neuroinflammation. Currently, PIPN effective treatments are lacking. Peroxisome Proliferator-Activated Receptor-α (PPAR-⍺) can modulate inflammatory responses. Thus, the use of PPAR-⍺ agonists, such as fibrates (fenofibrate and choline-fenofibrate), currently used in dyslipidemia treatment, could represent an interesting therapeutic approach in PIPN.

EXPERIMENTAL APPROACH

Our studies tested the efficacy of fenofibrate (150 mg/kg, daily, i.p.) and choline fenofibrate (60 mg/kg daily, p.o.) in reversing and preventing the development of PIPN (paclitaxel: 8 mg/kg, i.p., every other day for 4 days) in male and female C57BL/6J mice. Mechanical and cold hypersensitivity, conditioned place preference, sensory nerve action potential (SNAP), as well as the expression of PPAR-⍺, TNF-⍺, IL-1β and IL-6 mRNA were evaluated.

KEY RESULTS

While fenofibrate treatment partially reversed and prevented the development of mechanical hypersensitivity, this was completely reversed and prevented by choline-fenofibrate. Both fibrates were able to completely reverse and prevent cold hypersensitivity induced by paclitaxel. The reduction of SNAP amplitude induced by paclitaxel was also reversed by both fenofibrate and choline-fenofibrate. Our results indicate that suppression of paclitaxel-induced hypersensitivity by fibrates involves the regulation of PPAR-⍺ expression and decrease neuroinflammation in DRG. Finally, the co-treatment of Paclitaxel and fenofibric acid (fibrates active metabolite) was tested on different cancer cell lines, no decrease in the antitumoral effect of paclitaxel was observed.

CONCLUSIONS AND IMPLICATIONS

Taken together, our results show for the first time the therapeutic potential (prevention and reversal) of fibrates in PIPN and opens to a potential pharmacological repurposing of these drugs.

Thiazolidine Derivatives Attenuate Carrageenan-Induced Inflammatory Pain in Mice

BACKGROUND

Peripheral inflammation leads to the development of persistent thermal hyperalgesia and mechanical allodynia associated with increased expression of interleukin-1β (IL-1β) in the spinal cord. The aim of the present study was to investigate the effects of thiazolidine derivatives, 1b ([2-(2-hydroxyphenyl)-1,3-thiazolidin-4-yl](morpholin-4-yl)methanone) and 1d (2-hydroxy-4-{[2-(2-hydroxyphenyl)-1,3-thiazolidine-4-carbonyl]amino}benzoic acid), on thermal hyperalgesia, mechanical allodynia and on IL-1β expression during carrageenan-induced inflammation in the spinal cord in mice. Inflammatory pain was induced by injecting 1% carrageenan into the right hind paw of the mice.

METHODS

The animals were administered thiazolidine derivatives, 1b and 1d (1 mg/kg, 3 mg/kg, or 10 mg/kg), intraperitoneally 30 minutes before carrageenan administration. The animals' behavior was evaluated by measuring thermal hyperalgesia, mechanical allodynia, and motor coordination. The IL-1β expression was measured by enzyme-linked immunosorbent assay. Acute and sub-acute toxicity studies were conducted to evaluate the toxicity profile of compounds.

RESULTS

Treatment with the thiazolidine derivative, 1b and 1d, attenuated carrageenan-induced thermal hyperalgesia and mechanical allodynia at doses of 1 mg/kg, 3 mg/kg, and 10 mg/kg. No motor coordination deficits were observed in animals. The compounds also reduced IL-1β expression in the spinal cord of mice. Acute and sub-acute toxicity studies revealed that both compounds were safe.

CONCLUSION

The compounds exhibit promising activity against inflammatory pain due to their ability to produce anti-hyperalgesic and anti-allodynic effects and to inhibit IL-1β expression in the spinal cord.

Inhibition of the Soluble Epoxide Hydrolase as an Analgesic Strategy: A Review of Preclinical Evidence

Chronic pain is a complicated condition which causes substantial physical, emotional, and financial impacts on individuals and society. However, due to high cost, lack of efficacy and safety problems, current treatments are insufficient. There is a clear unmet medical need for safe, nonaddictive and effective therapies in the management of pain. Epoxy-fatty acids (EpFAs), which are natural signaling molecules, play key roles in mediation of both inflammatory and neuropathic pain sensation. However, their molecular mechanisms of action remain largely unknown. Soluble epoxide hydrolase (sEH) rapidly converts EpFAs into less bioactive fatty acid diols in vivo; therefore, inhibition of sEH is an emerging therapeutic target to enhance the beneficial effect of natural EpFAs. In this review, we will discuss sEH inhibition as an analgesic strategy for pain management and the underlying molecular mechanisms.

A KCa3.1 Channel Opener, ASP0819, Modulates Nociceptive Signal Processing from Peripheral Nerves in Fibromyalgia-Like Pain in Rats

Purpose

Although abnormal peripheral and central pain processing has been observed in fibromyalgia (FM) patients, the biomechanics and pathophysiology, surrounding the peripheral mechanism are not well understood. An intermediate conductance channel, K_Ca3.1, is expressed in peripheral sensory nerve fibers where it maintains the resting membrane potential and controls nerve firing, making it a plausible target for peripheral therapeutic interventions. ASP0819, a K_Ca3.1 channel opener, is an orally available molecular entity and is used in this investigation to elucidate the role of K_Ca3.1 in signal processing of pain in FM.

Methods

Human or rat K_Ca3.1 channel-expressing cells were used for evaluating the main action of the compound. Effects of the compound on withdrawal behavior by mechanical stimulation were examined in reserpine-induced myalgia (RIM) and vagotomy-induced myalgia (VIM) models of rats. In addition, in vivo electrophysiological analysis was performed to examine the peripheral mechanisms of action of the compound. Other pain models were also examined.

Results

ASP0819 increased the negative membrane potential in a concentration-dependent manner. Oral administration of ASP0819 significantly recovered the decrease in muscle pressure threshold in rat FM models of RIM and VIM. The in vivo electrophysiological experiments showed that Aδ- and C-fibers innervating the leg muscles in the RIM model demonstrated increased spontaneous and mechanically evoked firing compared with normal rats. Intravenous infusion of ASP0819 significantly reduced both the spontaneous activity and mechanically evoked responses in Aδ-fibers in the rat RIM model. ASP0819 significantly reduced the number of abdominal contractions as an indicator of abdominal pain behaviors in the rat visceral extension model and withdrawal responses in the osteoarthritis model, respectively.

Conclusion

These findings suggest that ASP0819 may be a promising analgesic agent with the ability to modulate peripheral pain signal transmission. Its use in the treatment of several pain conditions should be explored, chief amongst these being FM pain.

N-acylethanolamine acid amidase (NAAA) inhibition decreases the motivation for alcohol in Marchigian Sardinian alcohol-preferring rats

RATIONALE

N-acylethanolamine acid amidase (NAAA) is an intracellular cysteine hydrolase that terminates the biological actions of oleoylethanolamide (OEA) and palmitoylethanolamide (PEA), two endogenous lipid-derived agonists of the nuclear receptor, and peroxisome proliferator-activated receptor-α. OEA and PEA are important regulators of energy balance, pain, and inflammation, but recent evidence suggests that they might also contribute to the control of reward-related behaviors.

OBJECTIVES AND METHODS

In the present study, we investigated the effects of systemic and intracerebral NAAA inhibition in the two-bottle choice model of voluntary alcohol drinking and on operant alcohol self-administration.

RESULTS

Intraperitoneal injections of the systemically active NAAA inhibitor ARN19702 (3 and 10 mg/kg) lowered voluntary alcohol intake in a dose-dependent manner, achieving ≈ 47% reduction at the 10 mg/kg dose (p < 0.001). Water, food, or saccharin consumption was not affected by the inhibitor. Similarly, ARN19702 dose-dependently attenuated alcohol self-administration under both fixed ratio 1 (FR-1) and progressive ratio schedules of reinforcement. Furthermore, microinjection of ARN19702 (1, 3 and 10 μg/μl) or of two chemically different NAAA inhibitors, ARN077 and ARN726 (both at 3 and 10 μg/μl), into the midbrain ventral tegmental area produced dose-dependent decreases in alcohol self-administration under FR-1 schedule. Microinjection of ARN19702 into the nucleus accumbens had no such effect.

CONCLUSION

Collectively, the results point to NAAA as a possible molecular target for the treatment of alcohol use disorder.

A Fenofibrate Diet Prevents Paclitaxel-Induced Peripheral Neuropathy in Mice

Simple Summary

Paclitaxel, a drug used in the treatment of malignancies such as lung, ovarian and breast cancer, often produces severe side effects, among which is peripheral neuropathy. This neuropathy involves diffuse or localized pain, notably burning pain, cold and mechanical hyperexcitability. Recently, fenofibrate, a Food and Drug Administration (FDA)-approved drug for the treatment of dyslipidemia, has been shown to reduce the severity of symptoms in other forms of peripheral neuropathy. In the current work, we tested whether fenofibrate could reverse mechanical and cold hypersensitivity and improve motivation and the reduction in nerve conduction in a mouse model of paclitaxel-induced neuropathy. Our behavioral, histological and molecular assessments indicate that fenofibrate prevents the development of paclitaxel-induced neuropathy. Taken together, our studies support the therapeutic potential of fenofibrate in the prevention of paclitaxel-induced neuropathy and suggest the possible repurposing of this drug for this purpose in the clinic.

Abstract

Background: Paclitaxel-induced peripheral neuropathy (PIPN) is a major adverse effect of this chemotherapeutic agent that is used in the treatment of a number of solid malignancies. PIPN leads notably to burning pain, cold and mechanical allodynia. PIPN is thought to be a consequence of alterations of mitochondrial function, hyperexcitability of neurons, nerve fiber loss, oxidative stress and neuroinflammation in dorsal root ganglia (DRG) and spinal cord (SC). Therefore, reducing neuroinflammation could potentially attenuate neuropathy symptoms. Peroxisome proliferator-activated receptor-α (PPAR-α) nuclear receptors that modulate inflammatory responses can be targeted by non-selective agonists, such as fenofibrate, which is used in the treatment of dyslipidemia. Methods: Our studies tested the efficacy of a fenofibrate diet (0.2% and 0.4%) in preventing the development of PIPN. Paclitaxel (8 mg/kg) was administered via 4 intraperitoneal (i.p.) injections in C57BL/6J mice (both male and female). Mechanical and cold hypersensitivity, wheel running activity, sensory nerve action potential (SNAP), sciatic nerve histology, intra-epidermal fibers, as well as the expression of PPAR-α and neuroinflammation were evaluated in DRG and SC. Results: Fenofibrate in the diet partially prevented the development of mechanical hypersensitivity but completely prevented cold hypersensitivity and the decrease in wheel running activity induced by paclitaxel. The reduction in SNAP amplitude induced by paclitaxel was also prevented by fenofibrate. Our results indicate that suppression of paclitaxel-induced pain by fenofibrate involves the regulation of PPAR-α expression through reduction in neuroinflammation. Finally, co-administration of paclitaxel and the active metabolite of fenofibrate (fenofibric acid) did not interfere with the suppression of tumor cell growth or clonogenicity by paclitaxel in ovarian and breast cancer cell lines. Conclusions: Taken together, our results show the therapeutic potential of fenofibrate in the prevention of PIPN development.

The Basal Pharmacology of Palmitoylethanolamide

Palmitoylethanolamide (PEA, N-hexadecanoylethanolamide) is an endogenous compound belonging to the family of N-acylethanolamines. PEA has anti-inflammatory and analgesic properties and is very well tolerated in humans. In the present article, the basal pharmacology of PEA is reviewed. In terms of its pharmacokinetic properties, most work has been undertaken upon designing formulations for its absorption and upon characterising the enzymes involved in its metabolism, but little is known about its bioavailability, tissue distribution, and excretion pathways. PEA exerts most of its biological effects in the body secondary to the activation of peroxisome proliferator-activated receptor-α (PPAR-α), but PPAR-α-independent pathways involving other receptors (Transient Receptor Potential Vanilloid 1 (TRPV1), GPR55) have also been identified. Given the potential clinical utility of PEA, not least for the treatment of pain where there is a clear need for new well-tolerated drugs, we conclude that the gaps in our knowledge, in particular those relating to the pharmacokinetic properties of the compound, need to be filled.

Reversal of diet-induced hepatic steatosis by peripheral CB1 receptor blockade in mice is p53/miRNA-22/SIRT1/PPARα dependent

OBJECTIVE

The endocannabinoid (eCB) system is increasingly recognized as being crucially important in obesity-related hepatic steatosis. By activating the hepatic cannabinoid-1 receptor (CB₁R), eCBs modulate lipogenesis and fatty acid oxidation. However, the underlying molecular mechanisms are largely unknown.

METHODS

We combined unbiased bioinformatics techniques, mouse genetic manipulations, multiple pharmacological, molecular, and cellular biology approaches, and genomic sequencing to systematically decipher the role of the hepatic CB₁R in modulating fat utilization in the liver and explored the downstream molecular mechanisms.

RESULTS

Using an unbiased normalized phylogenetic profiling analysis, we found that the CB₁R evolutionarily coevolves with peroxisome proliferator-activated receptor-alpha (PPARα), a key regulator of hepatic lipid metabolism. In diet-induced obese (DIO) mice, peripheral CB₁R blockade (using AM6545) induced the reversal of hepatic steatosis and improved liver injury in WT, but not in PPARα^-/- mice. The antisteatotic effect mediated by AM6545 in WT DIO mice was accompanied by increased hepatic expression and activity of PPARα as well as elevated hepatic levels of the PPARα-activating eCB-like molecules oleoylethanolamide and palmitoylethanolamide. Moreover, AM6545 was unable to rescue hepatic steatosis in DIO mice lacking liver sirtuin 1 (SIRT1), an upstream regulator of PPARα. Both of these signaling molecules were modulated by the CB₁R as measured in hepatocytes exposed to lipotoxic conditions or treated with CB₁R agonists in the absence/presence of AM6545. Furthermore, using microRNA transcriptomic profiling, we found that the CB₁R regulated the hepatic expression, acetylation, and transcriptional activity of p53, resulting in the enhanced expression of miR-22, which was found to specifically target SIRT1 and PPARα.

CONCLUSIONS

We provide strong evidence for a functional role of the p53/miR-22/SIRT1/PPARα signaling pathway in potentially mediating the antisteatotic effect of peripherally restricted CB₁R blockade.

Anti-nociceptive effect of Arbutus andrachne L. methanolic leaf extract mediated by CB1, TRPV1 and PPARs in mouse pain models

Arbutus andrachne L. is a medicinal plant that grows in Jordan and has many valuable effects. In the present study, the anti-nociceptive effect of A. andrachne methanolic leaf extract was determined in mice using thermal and chemical tests. Our findings show that different doses of A. andrachne extract reduced the number of writhings significantly compared to control group. The leaf extract also reduced the time of paw licking in the early and late phases of formalin test. In all the conducted tests, 300 mg/kg body wt. was the best effective dose. A peroxisome proliferator-activated receptor alpha (PPARα) antagonist reversed the action of the plant extract in the early phase of formalin test while antagonists of the PPARα, PPAR gamma (PPARγ) and cannabinoid 1 (CB1) receptors were responsible for abolishing its effect in the late phase of this test. Also, the extract administration increased the latency time in hot plate and tail flick, an effect that was reversed by the antagonists of PPARγ, CB1 and transient receptor potential vanilloid 1 (TRPV1). No effect was noticed for α₂-adrenergic receptor antagonist in the action of A. andrachne in any of the conducted tests in this study. Furthermore, analysis of the constituents in the methanolic leaf extract using liquid chromatography mass spectrometry (LCMS) showed that the extract is rich in compounds that have anti-nociceptive and/or anti-inflammatory effects such as arbutin, rutin, linalool, linoleic acid, gallic acid, lauric acid, myristic acid, hydroquinone, β-sitosterol, ursolic acid, isoquercetin, quercetin, (+)-gallocatechin, kaempferol, α-tocopherol, myricetin 3-O-rhamnoside and catechin gallate. In conclusion, A. andrachne showed promising anti-nociceptive effects in thermal and chemical models of pain. These findings can open an avenue for natural pain relief.

PPARα-Dependent Effects of Palmitoylethanolamide Against Retinal Neovascularization and Fibrosis

Purpose

Pathological neovascularization and fibrosis are common pathological changes of many retinal diseases, such as proliferative retinopathy (PR) and age-related macular degeneration (AMD). Treatment modalities for these pathological changes are limited. The purpose of the present study was to test the effects of palmitoylethanolamide (PEA), an endocannabinoid mimetic amide, on retinal neovascularization and fibrosis and to determine its molecular mechanism of action.

Methods

A rat Müller cell line (rMC-1), a mouse model of oxygen-induced retinopathy (OIR), and the very-low-density lipoprotein receptor (VLDLR) knockout mouse model were used. PEA was intraperitoneally injected or orally administrated in animal models. Inflammation and profibrotic changes were evaluated by western blot analysis. Glial fibrillary acidic protein (GFAP) and peroxisome proliferator-activated receptor alpha (PPARα) were measured by RT-PCR and western blot analysis.

Results

Profibrotic changes were present in OIR and Vldlr-/- retinas. PEA significantly alleviated inflammation and inhibited neovascularization in OIR and Vldlr-/- retinas and suppressed profibrotic changes in OIR and Vldlr-/- retinas. Moreover, PEA potently suppressed Müller gliosis in these retinas. In rMC-1 cells, PEA suppressed Müller gliosis, reduced inflammatory cytokines, and attenuated profibrotic changes. Further, both mRNA and protein levels of PPARα were elevated in the retina under PEA treatment, and the effects of PEA were abolished in Pparα-/- OIR mice.

Conclusions

PEA reduced retinal neovascularization and fibrotic changes and suppressed Müller gliosis in experimental PR and neovascular AMD by activating PPARα. PEA may be a potential treatment for retinopathies with pathological neovascularization and fibrosis.

Localisation of cannabinoid and cannabinoid-related receptors in the equine dorsal root ganglia

BACKGROUND

Growing evidence recognises cannabinoid receptors as potential therapeutic targets for pain. Consequently, there is increasing interest in developing cannabinoid receptor agonists for treating pain. As a general rule, to better understand the actions of a drug, it would be of extreme importance to know the cellular distribution of its specific receptors. The localisation of cannabinoid receptors in the dorsal root ganglia of the horse has not yet been investigated.

OBJECTIVES

To localise the cellular distribution of canonical and putative cannabinoid receptors in the equine cervical dorsal root ganglia.

STUDY DESIGN

Qualitative and quantitative immunohistochemical study.

METHODS

Cervical (C6-C8) dorsal root ganglia were collected from six horses (1.5 years of age) at the slaughterhouse. The tissues were fixed and processed to obtain cryosections which were used to investigate the immunoreactivity of canonical cannabinoid receptors 1 (CB1R) and 2 (CB2R), and for three putative cannabinoid-related receptors: nuclear peroxisome proliferator-activated receptor alpha (PPARα), transient receptor potential ankyrin 1 (TRPA1) and serotonin 5-HT1a receptor (5-HT1aR).

RESULTS

The neurons showed immunoreactivity for CB1R (100%), CB2R (80% ± 13%), PPARα (100%), TRPA1 (74% ± 10%) and 5-HT1aR (84% ± 6%). The neuronal satellite glial cells showed immunoreactivity for CB2R, PPARα, TRPA1 and 5-HT1aR.

MAIN LIMITATIONS

The low number of horses included in the study.

CONCLUSIONS

This study highlighted the expression of cannabinoid receptors in the sensory neurons and glial cells of the dorsal root ganglia. These findings could be of particular relevance for future functional studies assessing the effects of cannabinoids in horses to manage pain.

N-Acylethanolamine Acid Amidase contributes to disease progression in a mouse model of multiple sclerosis

N-Acylethanolamine acid amidase (NAAA) deactivates the endogenous peroxisome proliferator-activated receptor-α (PPAR-α) agonist palmitoylethanolamide (PEA). NAAA-regulated PEA signaling participates in the control of peripheral inflammation, but evidence suggests also a role in the modulation of neuroinflammatory pathologies such as multiple sclerosis (MS). Here we show that disease progression in the mouse experimental autoimmune encephalomyelitis (EAE) model of MS is accompanied by induction of NAAA expression in spinal cord, which in presymptomatic animals is confined to motor neurons and oligodendrocytes but, as EAE progresses, extends to microglia/macrophages and other cell types. As previously reported for NAAA inhibition, genetic NAAA deletion delayed disease onset and attenuated symptom intensity in female EAE mice, suggesting that accrued NAAA expression may contribute to pathology. To further delineate the role of NAAA in EAE, we generated a mouse line that selectively overexpresses the enzyme in macrophages, microglia and other monocyte-derived cells. Non-stimulated alveolar macrophages from these Naaa^CD11b+ mice contain higher-than-normal levels of inducible nitric oxide synthase and display an activated morphology. Furthermore, intranasal lipopolysaccharide injections cause greater alveolar leukocyte accumulation in Naaa^CD11b+ than in control mice. Naaa^CD11b+ mice also display a more aggressive clinical response to EAE induction, compared to their wild-type littermates. The results identify NAAA as a critical control step in EAE pathogenesis, and point to this enzyme as a possible target for the treatment of MS.

Palmitoylethanolamide and Related ALIAmides: Prohomeostatic Lipid Compounds for Animal Health and Wellbeing

Virtually every cellular process is affected by diet and this represents the foundation of dietary management to a variety of small animal disorders. Special attention is currently being paid to a family of naturally occurring lipid amides acting through the so-called autacoid local injury antagonism, i.e., the ALIA mechanism. The parent molecule of ALIAmides, palmitoyl ethanolamide (PEA), has being known since the 1950s as a nutritional factor with protective properties. Since then, PEA has been isolated from a variety of plant and animal food sources and its proresolving function in the mammalian body has been increasingly investigated. The discovery of the close interconnection between ALIAmides and the endocannabinoid system has greatly stimulated research efforts in this field. The multitarget and highly redundant mechanisms through which PEA exerts prohomeostatic functions fully breaks with the classical pharmacology view of “one drug, one target, one disease”, opening a new era in the management of animals’ health, i.e., an according-to-nature biomodulation of body responses to different stimuli and injury. The present review focuses on the direct and indirect endocannabinoid receptor agonism by PEA and its analogues and also targets the main findings from experimental and clinical studies on ALIAmides in animal health and wellbeing.

Inhibition of fatty acid amide hydrolase in the CNS prevents and reverses morphine tolerance in male and female mice

BACKGROUND AND PURPOSE

Fatty acid amide hydrolase (FAAH) is an intracellular serine amidase that terminates the signalling of various lipid messengers involved in pain regulation, including anandamide and palmitoylethanolamide. Here, we investigated the effects of pharmacological or genetic FAAH removal on tolerance to the anti-nociceptive effects of morphine.

EXPERIMENTAL APPROACH

We induced tolerance in male and female mice by administering twice-daily morphine for 7 days while monitoring nociceptive thresholds by the tail immersion test. The globally active FAAH inhibitor URB597 (1 and 3 mg·kg^-1 , i.p.) or the peripherally restricted FAAH inhibitor URB937 (3 mg·kg^-1 , i.p.) were administered daily 30 min prior to morphine, alone or in combination with the cannabinoid CB₁ receptor antagonist AM251 (3 mg·kg^-1 , i.p.), the CB₂ receptor antagonist AM630 (3 mg·kg^-1 , i.p.), or the PPAR-α antagonist GW6471 (4 mg·kg^-1 , i.p.). Spinal levels of FAAH-regulated lipids were quantified by LC/MS-MS. Gene transcription was assessed by RT-qPCR.

KEY RESULTS

URB597 prevented and reversed morphine tolerance in both male and female mice. This effect was mimicked by genetic FAAH deletion, but not by URB937. Treatment with AM630 suppressed, whereas treatment with AM251 or GW6471, attenuated the effects of URB597. Anandamide mobilization was enhanced in the spinal cord of morphine-tolerant mice. mRNA levels of the anandamide-producing enzyme N-acyl-phosphatidylethanolamine PLD (NAPE-PLD) and the palmitoylethanolamide receptor PPAR-α, but not those for CB₂ , CB₁ receptors or FAAH, were elevated in spinal cord CONCLUSION AND IMPLICATIONS: FAAH-regulated lipid signalling in the CNS modulated opiate tolerance, suggesting FAAH as a potential target for opiate-sparing medications.

N-Acylethanolamine Acid Amidase (NAAA): Structure, Function, and Inhibition

N-Acylethanolamine acid amidase (NAAA) is an N-terminal cysteine hydrolase primarily found in the endosomal-lysosomal compartment of innate and adaptive immune cells. NAAA catalyzes the hydrolytic deactivation of palmitoylethanolamide (PEA), a lipid-derived peroxisome proliferator-activated receptor-α (PPAR-α) agonist that exerts profound anti-inflammatory effects in animal models. Emerging evidence points to NAAA-regulated PEA signaling at PPAR-α as a critical control point for the induction and the resolution of inflammation and to NAAA itself as a target for anti-inflammatory medicines. The present Perspective discusses three key aspects of this hypothesis: the role of NAAA in controlling the signaling activity of PEA; the structural bases for NAAA function and inhibition by covalent and noncovalent agents; and finally, the potential value of NAAA-targeting drugs in the treatment of human inflammatory disorders.

Pharmacological Blockade of PPAR Isoforms Increases Conditioned Fear Responding in the Presence of Nociceptive Tone

Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors with three isoforms (PPARα, PPARβ/δ, PPARγ) and can regulate pain, anxiety, and cognition. However, their role in conditioned fear and pain-fear interactions has not yet been investigated. Here, we investigated the effects of systemically administered PPAR antagonists on formalin-evoked nociceptive behaviour, fear-conditioned analgesia (FCA), and conditioned fear in the presence of nociceptive tone in rats. Twenty-three and a half hours following fear conditioning to context, male Sprague-Dawley rats received an intraplantar injection of formalin and intraperitoneal administration of vehicle, PPARα (GW6471), PPARβ/δ (GSK0660) or PPARγ (GW9662) antagonists, and 30 min later were re-exposed to the conditioning arena for 15 min. The PPAR antagonists did not alter nociceptive behaviour or fear-conditioned analgesia. The PPARα and PPARβ/δ antagonists prolonged context-induced freezing in the presence of nociceptive tone without affecting its initial expression. The PPARγ antagonist potentiated freezing over the entire trial. In conclusion, pharmacological blockade of PPARα and PPARβ/δ in the presence of formalin-evoked nociceptive tone, impaired short-term, within-trial fear-extinction in rats without affecting pain response, while blockade of PPARγ potentiated conditioned fear responding. These results suggest that endogenous signalling through these three PPAR isoforms may reduce the expression of conditioned fear in the presence of nociceptive tone.

A systematic review of the effects of oleoylethanolamide, a high-affinity endogenous ligand of PPAR-α, on the management and prevention of obesity

Along with an increase in overweight and obesity among all age groups, the development of efficacious and safe anti-obesity strategies for patients, as well as health systems, is critical. Oleoylethanolamide (OEA), a high-affinity endogenous ligand of nuclear receptor peroxisome proliferator-activated receptor alpha (PPAR-α), plays important physiological and metabolic actions. OEA is derived from oleic acid, a monounsaturated fatty acid, which has beneficial effects on body composition and regional fat distribution. The role of OEA in the modulation of food consumption and weight management makes it an attractive molecule requiring further exploration in obesogenic environments. This systematic review was conducted to assess the effects of OEA on the obesity management, with emphasizing on its physiological roles and possible mechanisms of action in energy homeostasis. We searched PubMed/Medline, Google Scholar, ScienceDirect, Scopus, ProQuest, and EMBASE up until September 2019. Out of 712 records screened, 30 articles met the study criteria. The evidence reviewed here indicates that OEA, an endocannabinoid-like compound, leads to satiation or meal termination through PPAR-α activation and fatty acid translocase (FAT)/CD36. Additionally, the lipid-amide OEA stimulates fatty acid uptake, lipolysis, and beta-oxidation, and also promotes food intake control. OEA also exerts satiety-inducing effects by activating the hedonic dopamine pathways and increasing homeostatic oxytocin and brain histamine. In conclusion, OEA may be a key component of the physiological system involved in the regulation of dietary fat consumption and energy homeostasis; therefore, it is suggested as a possible therapeutic agent for the management of obesity.