N-Oleoyl-glycine reduces nicotine reward and withdrawal in mice

Early biomarkers in the presymptomatic phase of cognitive impairment: changes in the endocannabinoidome and serotonergic pathways in Alzheimer's-prone mice after mTBI

BACKGROUND

Despite extensive studies on the neurobiological correlates of traumatic brain injury (TBI), little is known about its molecular determinants on long-term consequences, such as dementia and Alzheimer's disease (AD).

METHODS

Here, we carried out behavioural studies and an extensive biomolecular analysis, including inflammatory cytokines, gene expression and the combination of LC-HRMS and MALDI-MS Imaging to elucidate the targeted metabolomics and lipidomics spatiotemporal alterations of brains from wild-type and APP-SWE mice, a genetic model of AD, at the presymptomatic stage, subjected to mild TBI.

RESULTS

We found that brain injury does not affect cognitive performance in APP-SWE mice. However, we detected an increase of key hallmarks of AD, including Aβ1-42 levels and BACE1 expression, in the cortices of traumatized transgenic mice. Moreover, significant changes in the expanded endocannabinoid (eCB) system, or endocannabinoidome (eCBome), occurred, including increased levels of the endocannabinoid 2-AG in APP-SWE mice in both the cortex and hippocampus, and N-acylserotonins, detected for the first time in the brain. The gene expression of enzymes for the biosynthesis and inactivation of eCBs and eCB-like mediators, and some of their main molecular targets, also underwent significant changes. We also identified the formation of heteromers between cannabinoid 1 (CB1) and serotonergic 2A (5HT2A) receptors, whose levels increased in the cortex of APP-SWE mTBI mice, possibly contributing to the exacerbated pathophysiology of AD induced by the trauma.

CONCLUSIONS

Mild TBI induces biochemical changes in AD genetically predisposed mice and the eCBome may play a role in the pathogenetic link between brain injury and neurodegenerative disorders also by interacting with the serotonergic system.

N-oleoyl alanine attenuates nicotine reward and spontaneous nicotine withdrawal in mice

BACKGROUND

As nicotine dependence represents a longstanding major public health issue, new nicotine cessation pharmacotherapies are needed. Administration of N-oleoyl glycine (OlGly), an endogenous lipid signaling molecule, prevents nicotine-induced conditioned place preference (CPP) through a peroxisome proliferator-activated receptor-alpha (PPARα) dependent mechanism, and also ameliorated withdrawal signs in nicotine-dependent mice. Pharmacological evidence suggests that the methylated analog of OlGly, N-oleoyl alanine (OlAla), has an increased duration of action and may offer translational benefit. Accordingly, OlAla was assessed in nicotine CPP and dependence assays as well as its pharmacokinetics compared to OlGly.

METHODS

ICR female and male mice were tested in nicotine-induced CPP with and without the PPARα antagonist GW6471. OlAla was also assessed in nicotine-dependent mice following removal of nicotine minipumps: somatic withdrawal signs, thermal hyper-nociception and altered affective behavior (i.e., light/dark box). Finally, plasma and brain were collected after administration of OlGly or OlAla and analyzed by high-performance liquid chromatography tandem mass spectrometry.

RESULTS

OlAla prevented nicotine-induced CPP, but this effect was not blocked by GW6471. OlAla attenuated somatic and affective nicotine withdrawal signs, but not thermal hyper-nociception in nicotine-dependent mice undergoing withdrawal. OlAla and OlGly showed similar time-courses in plasma and brain.

CONCLUSIONS

The observation that both molecules showed similar pharmacokinetics argues against the notion that OlAla offers increased metabolic stability. Moreover, while these structurally similar lipids show efficacy in mouse models of reward and dependence, they reduce nicotine reward through distinct mechanisms.

Combined pesticides in field doses weaken honey bee (Apis cerana F.) flight ability and analyses of transcriptomics and metabolomics

Imidacloprid, chlorpyrifos, and glyphosate rank among the most extensively employed pesticides worldwide. The effects of these pesticides and their combined on the flight capability of Apis cerana, and the potential underlying mechanisms remain uncertain. To investigate these effects, we carried out flight mill, transcriptome, and metabolome experiments. Our findings reveal that individual acute oral treatments with pesticides, specifically 20 μL of 10 ng/g imidacloprid (0.2 ng per bee), 30 ng/g chlorpyrifos (0.6 ng per bee), and 60 ng/g glyphosate (1.2 ng per bee), did not impact the flight capability of the bees. However, when bees were exposed to a combination of two or three pesticides, a notable reduction in flight duration and distance was observed. In the transcriptomic and metabolomic analyses, we identified 307 transcripts and 17 metabolites that exhibited differential expression following exposure to combined pesticides, primarily associated with metabolic pathways involved in energy regulation. Our results illuminate the intricate effects and potential hazards posed by combined pesticide exposures on bee behavior. These findings offer valuable insights into the synergistic potential of pesticide combinations and their capacity to impair bee behavior. Understanding these complex interactions is essential for comprehending the broader consequences of pesticide formulations on honey bee populations.

High-performance liquid chromatography-tandem mass spectrometry method for the analysis of N-oleoyl glycine and N-oleoyl alanine in brain and plasma

Interest has increased in the role of N-acyl amino acids in a variety of disease states and as potential pharmacotherapies. Recently, N-oleoyl glycine and N-oleoyl alanine have shown promise in reducing the rewarding effects of drugs of abuse and alleviating withdrawal signs in rodent models. Previously published methods for the quantitation of these analytes by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) in tissue were part of extensive lipidomic panels which may result in limited sensitivity and selectivity and also reported low recovery. Presented is a method for the extraction and HPLC-MS/MS analysis of N-oleoyl glycine and N-oleoyl alanine. The bias and precision of the assay were determined to be within ± 20%. The method was shown to be reliable and robust, with over 90% recovery for the low-level analytes. Increasing concentrations of N-oleoyl glycine and N-oleoyl alanine were quantitated in mouse brain and plasma following exogenous administration. This method was developed to serve to support studies investigating the pharmacokinetics and involvement of N-oleoyl glycine and N-oleoyl alanine in drug dependence and other diseases.

The long-term exercise after traumatic brain injury: Reharmonizing brain by sound body

Traumatic brain injuries (TBI) refer to multiple acquired dysfunctions arising from damage to the brain caused by an external force, including rapid acceleration/deceleration and concussion. Among them, mild TBI (mTBI) accounts for most cases (up to 90%) of injuries. It is responsible for a variety of symptoms, including anxiety, depression, and cognitive impairments that remain difficult to be treated. It has been reported that regular physical activity, as well as, improving life quality, display a neuroprotective function, suggesting a possible role in post-traumatic rehabilitation. In this study, we investigated the effects of treadmill exercise in a mice mTBI model by behavioural, electrophysiological and neurochemical analysis. Daily exercise decreased anxiety, aggressive behavior, and depression in mTBI mice. Accordingly, electrophysiological and neurochemical maladaptive rearrangement occurring in the hippocampus of mTBI mice were prevented by the exercise.

N-Oleoyl Glycine and Its Derivatives Attenuate the Acquisition and Expression of Cocaine-Induced Behaviors

Introduction: The endocannabinoid system (ECS) plays a key modulatory role during synaptic plasticity and homeostatic processes in the brain and plays an important role in the neurobiological processes underlying drug addiction. Impaired endocannabinoid (eCB) signaling contributes to dysregulated synaptic plasticity, increased stress responsivity, and craving that propel addiction. Therefore, we hypothesized that boosting the ECS by exogenous administration of selective eCBs will attenuate cocaine-induced behaviors. Materials and Methods: The behavioral paradigms included psychomotor sensitization (PS) and conditioned place preference (CPP). Liquid chromatography-mass spectrometry analysis was used for quantitative profiling of eCBs in mouse brain. Results: We first measured the levels of eCBs in different brain areas of the reward system following chronic cocaine treatment. We found that following daily administration of cocaine, the levels of N-oleoyl glycine (OlGly) were significantly elevated in the nucleus accumbens (NAc) in a region-specific manner. We next tested whether administration of OlGly will attenuate cocaine-induced behaviors. We found that administration of OlGly during withdrawal, but not during acquisition of PS, attenuated the expression of cocaine sensitization. In addition, the administration of OlGly during the acquisition of cocaine CPP, but not during withdrawal, attenuated the expression of cocaine-conditioned reward. To enhance the stability of OlGly and its duration of action, two methylated derivatives of OlGly were synthesized, the monomethylated OlGly (HU-595) and dimethylated OlGly (HU-596). We found that the effect of administration of HU-595 or HU-596 during cocaine conditioning did not differ from the OlGly-induced decrease in the expression of CPP. Conclusion: Our findings suggest that the ECS is involved in the common neurobiological mechanisms underlying the development and expression of cocaine reward and drug-seeking. Boosting the ECS exogenously has beneficial effects against cocaine-induced behaviors.

Olive oil-derived endocannabinoid-like mediators inhibit palatable food-induced reward and obesity

N-oleoylglycine (OlGly), a lipid derived from the basic component of olive oil, oleic acid, and N-oleoylalanine (OlAla) are endocannabinoid-like mediators. We report that OlGly and OlAla, by activating the peroxisome proliferator-activated receptor alpha (PPARα), reduce the rewarding properties of a highly palatable food, dopamine neuron firing in the ventral tegmental area, and the obesogenic effect of a high-fat diet rich in lard (HFD-L). An isocaloric olive oil HFD (HFD-O) reduced body weight gain compared to the HFD-L, in a manner reversed by PPARα antagonism, and enhanced brain and intestinal OlGly levels and gut microbial diversity. OlGly or OlAla treatment of HFD-L mice resulted in gut microbiota taxonomic changes partly similar to those induced by HFD-O. We suggest that OlGly and OlAla control body weight by counteracting highly palatable food overconsumption, and possibly rebalancing the gut microbiota, and provide a potential new mechanism of action for the obeso-preventive effects of olive oil-rich diets.

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

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

N-oleoyl glycine and N-oleoyl alanine attenuate alcohol self-administration and preference in mice

The endocannabinoid system (ECS) plays a key modulatory role during synaptic plasticity and homeostatic processes in the brain and has an important role in the neurobiological processes underlying drug addiction. We have previously shown that an elevated ECS response to psychostimulant (cocaine) is involved in regulating the development and expression of cocaine-conditioned reward and sensitization. We therefore hypothesized that drug-induced elevation in endocannabinoids (eCBs) and/or eCB-like molecules (eCB-Ls) may represent a protective mechanism against drug insult, and boosting their levels exogenously may strengthen their neuroprotective effects. Here, we determine the involvement of ECS in alcohol addiction. We first measured the eCBs and eCB-Ls levels in different brain reward system regions following chronic alcohol self-administration using LC-MS. We have found that following chronic intermittent alcohol consumption, N-oleoyl glycine (OlGly) levels were significantly elevated in the prefrontal cortex (PFC), and N-oleoyl alanine (OlAla) was significantly elevated in the PFC, nucleus accumbens (NAc) and ventral tegmental area (VTA) in a region-specific manner. We next tested whether exogenous administration of OlGly or OlAla would attenuate alcohol consumption and preference. We found that systemic administration of OlGly or OlAla (60 mg/kg, intraperitoneal) during intermittent alcohol consumption significantly reduced alcohol intake and preference without affecting the hedonic state. These findings suggest that the ECS negatively regulates alcohol consumption and boosting selective eCBs exogenously has beneficial effects against alcohol consumption and potentially in preventing relapse.

Hypoabsorptive surgeries cause limb-dependent changes in the gut endocannabinoidome and microbiome in association with beneficial metabolic effects

OBJECTIVE

To determine whether the metabolic benefits of hypoabsorptive surgeries are associated with changes in the gut endocannabinoidome (eCBome) and microbiome.

METHODS

Biliopancreatic diversion with duodenal switch (BPD-DS) and single anastomosis duodeno-ileal bypass with sleeve gastrectomy (SADI-S) were performed in diet-induced obese (DIO) male Wistar rats. Control groups fed a high-fat diet (HF) included sham-operated (SHAM HF) and SHAM HF-pair-weighed to BPD-DS (SHAM HF-PW). Body weight, fat mass gain, fecal energy loss, HOMA-IR, and gut-secreted hormone levels were measured. The levels of eCBome lipid mediators and prostaglandins were quantified in different intestinal segments by LC-MS/MS, while expression levels of genes encoding eCBome metabolic enzymes and receptors were determined by RT-qPCR. Metataxonomic (16S rRNA) analysis was performed on residual distal jejunum, proximal jejunum, and ileum contents.

RESULTS

BPD-DS and SADI-S reduced fat gain and HOMA-IR, while increasing glucagon-like peptide-1 (GLP-1) and peptide tyrosine tyrosine (PYY) levels in HF-fed rats. Both surgeries induced potent limb-dependent alterations in eCBome mediators and in gut microbial ecology. In response to BPD-DS and SADI-S, changes in gut microbiota were significantly correlated with those of eCBome mediators. Principal component analyses revealed connections between PYY, N-oleoylethanolamine (OEA), N-linoleoylethanolamine (LEA), Clostridium, and Enterobacteriaceae_g_2 in the proximal and distal jejunum and in the ileum.

CONCLUSIONS

BPD-DS and SADI-S caused limb-dependent changes in the gut eCBome and microbiome. The present results indicate that these variables could significantly influence the beneficial metabolic outcome of hypoabsorptive bariatric surgeries.

A Delightful Trip Along the Pathway of Cannabinoid and Endocannabinoid Chemistry and Pharmacology

After a traumatic childhood in Europe during the Second World War, I found that scientific research in Israel was a pleasure beyond my expectations. Over the last 65 year, I have worked on the chemistry and pharmacology of natural products. During the last few decades, most of my research has been on plant cannabinoids, the endogenous cannabinoids arachidonoyl ethanolamide (anandamide) and 2-arachidonoyl glycerol, and endogenous anandamide-like compounds, all of which are involved in a wide spectrum of physiological reactions. Two plant cannabinoids, Δ⁹-tetrahydrocannabinol and cannabidiol, are approved drugs. However, the endogenous cannabinoids and the anandamide-like constituents have not yet been well investigated in humans. For me, intellectual freedom-the ability to do research based on my own scientific interests-has been the most satisfying part of my working life. Looking back over the 91 years of my long life, I conclude that I have been lucky, very lucky, both personally and scientifically.

The endocannabinoidome mediator N-oleoylglycine is a novel protective agent against 1-methyl-4-phenyl-pyridinium-induced neurotoxicity

N-oleoylglycine (OlGly) is a lipid mediator that belongs to the expanded version of the endocannabinoid (eCB) system, the endocannabinoidome (eCBome), which has recently gained increasing attention from the scientific community for its protective effects in a mouse model of mild traumatic brain injury. However, the effects of OlGly on cellular models of Parkinson’s disease (PD) have not yet been investigated, whilst other lipoaminoacids have been reported to have beneficial effects. Moreover, the protective effects of OlGly seem to be mediated by direct activation of proliferator-activated receptor alpha (PPARα), which has already been investigated as a therapeutic target for PD. Therefore, this study aims to investigate the possible protective effects of OlGly in an in vitro model obtained by treating the neuroblastoma cell line, SH-SY5Y (both differentiated and not) with 1-methyl-4-phenyl-pyridinium (MPP⁺), which mimics some cellular aspects of a PD-like phenotype, in the presence or absence of the PPARα antagonist, GW6471. Our data show that MPP⁺ increases mRNA levels of PPARα in both non differentiated and differentiated cells. Using assays to assess cell metabolic activity, cell proliferation, and pro-inflammatory markers, we observed that OlGly (1 nM), both as treatment (1 h) and pre-treatment (4 h), is able to protect against neuronal damage induced by 24 h MPP⁺ exposure through PPARα. Moreover, using a targeted lipidomics approach, we demonstrate that OlGly exerts its effects also through the modulation of the eCBome. Finally, treatment with OlGly was able also to reduce increased IL-1β induced by MPP⁺ in differentiated cells. In conclusion, our results suggest that OlGly could be a promising therapeutic agent for the treatment of MPP⁺-induced neurotoxicity.

Facile and Sustainable Synthesis of Commendamide and its Analogues

Commendamide, or N-(3-hydroxypalmitoyl)-glycine 1a, is a gut microbiota-derived bioactive metabolite, structurally similar to long-chain N-acyl-amino acids which belong to the complex lipid signaling system known as endocannabinoidome and play important roles in mammals through activation of, inter alia, G-protein-coupled receptors (GPCRs). In this work, we describe a simple, green and economic method for the preparation of commendamide 1a, a GPCR G2A/132 agonist. The developed protocol is general and could also be applied to the synthesis of deuterated commendamide 1b, as well as to other minor microbiota-derived metabolites, such as the analog 2.

Effect of oleoyl glycine and oleoyl alanine on lithium chloride induced nausea in rats and vomiting in shrews

RATIONALE

The fatty acid amide oleoyl glycine (OlGly) and its more stable methylated form oleoyl alanine (OlAla) reduce naloxone-precipitated morphine withdrawal (MWD)-induced conditioned gaping (nausea) responses in rats. In addition, OlGly has been shown to reduce lithium chloride (LiCl)-induced conditioned gaping in rats and vomiting in Suncus murinus (house musk shrews).

OBJECTIVES

Here, we compared the potential of these fatty acid amides to maintain their anti-nausea/anti-emetic effect over a delay. The following experiments examined the potential of a wider dose range of OlGly and OlAla to interfere with (1) LiCl-induced conditioned gaping in rats and (2) LiCl-induced vomiting in shrews, when administered 20 or 70 min prior to illness.

RESULTS

OlAla (1, 5, 20 mg/kg) reduced LiCl-induced conditioned gaping, with OlGly only effective at the high dose (20 mg/kg), with no effect of pretreatment delay time. At the high dose of 20 mg/kg, OlGly increased passive drips during conditioning suggesting a sedative effect. In shrews, both OlGly and OlAla (1, 5 mg/kg) suppressed LiCl-induced vomiting, with no effect of pretreatment delay. OlAla more effectively suppressed vomiting, with OlAla (5 mg/kg) also increasing the latency to the first vomiting reaction.

CONCLUSIONS

OlAla was more effective than OlGly in reducing both LiCl-induced gaping in rats and LiCl-induced vomiting in shrews. These findings provide further evidence that these fatty acid amides may be useful treatments for nausea and vomiting, with OlAla demonstrating superior efficacy.

The impact of cigarette smoking and nicotine on traumatic brain injury: a review

INTRODUCTION

Traumatic Brain Injury (TBI) and tobacco smoking are both serious public health problems. Many people with TBI also smoke. Nicotine, a component of tobacco smoke, has been identified as a premorbid neuroprotectant in other neurological disorders. This study aims to provide better understanding of relationships between tobacco smoking and nicotine use and effect on outcome/recovery from TBI.

METHODS

PubMed database, SCOPUS, and PTSDpub were searched for relevant English-language papers.

RESULTS

Twenty-nine human clinical studies and nine animal studies were included. No nicotine-replacement product use in human TBI clinical studies were identified. While smoking tobacco prior to injury can be harmful primarily due to systemic effects that can compromise brain function, animal studies suggest that nicotine as a pharmacological agent may augment recovery of cognitive deficits caused by TBI.

CONCLUSIONS

While tobacco smoking before or after TBI has been associated with potential harms, many clinical studies downplay correlations for most expected domains. On the other hand, nicotine could provide potential treatment for cognitive deficits following TBI by reversing impaired signaling pathways in the brain including those involving nAChRs, TH, and dopamine. Future studies regarding the impact of cigarette smoking and vaping on patients with TBI are needed .

Spontaneous and Naloxone-Precipitated Withdrawal Behaviors From Chronic Opiates are Accompanied by Changes in N-Oleoylglycine and N-Oleoylalanine Levels in the Brain and Ameliorated by Treatment With These Mediators

Rationale: The endocannabinoidome mediators, N-Oleoylglycine (OlGly) and N-Oleoylalanine (OlAla), have been shown to reduce acute naloxone-precipitated morphine withdrawal affective and somatic responses.

Objectives: To determine the role and mechanism of action of OlGly and OlAla in withdrawal responses from chronic exposure to opiates in male Sprague-Dawley rats.

Methods: Opiate withdrawal was produced: 1) spontaneously 24 h following chronic exposure to escalating doses of morphine over 14 days (Experiments 1 and 2) and steady-state exposure to heroin by minipumps for 12 days (Experiment 3), 2) by naloxone injection during steady-state heroin exposure (Experiment 4), 3) by naloxone injection during operant heroin self-administration (Experiment 5).

Results: In Experiment 1, spontaneous morphine withdrawal produced somatic withdrawal reactions. The behavioral withdrawal reactions were accompanied by suppressed endogenous levels of OlGly in the nucleus accumbens, amygdala, and prefrontal cortex, N-Arachidonylglycerol and OlAla in the amygdala, 2-arachidonoylglycerol in the nucleus accumbens, amygdala and interoceptive insular cortex, and by changes in colonic microbiota composition. In Experiment 2, treatment with OlAla, but not OlGly, reduced spontaneous morphine withdrawal responses. In Experiment 3, OlAla attenuated spontaneous steady-state heroin withdrawal responses at both 5 and 20 mg/kg; OlGly only reduced withdrawal responses at the higher dose of 20 mg/kg. Experiment 4 demonstrated that naloxone-precipitated heroin withdrawal from steady-state exposure to heroin (7 mg/kg/day for 12 days) is accompanied by tissue-specific changes in brain or gut endocannabinoidome mediator, including OlGly and OlAla, levels and colonic microbiota composition, and that OlAla (5 mg/kg) attenuated behavioural withdrawal reactions, while also reversing some of the changes in brain and gut endocannabinoidome and gut microbiota induced by naloxone. Experiment 5 demonstrated that although OlAla (5 mg/kg) did not interfere with operant heroin self-administration on its own, it blocked naloxone-precipitated elevation of heroin self-administration behavior.

Conclusion: These results suggest that OlAla and OlGly are two endogenous mediators whose brain concentrations respond to chronic opiate treatment and withdrawal concomitantly with changes in colon microbiota composition, and that OlAla may be more effective than OlGly in suppressing chronic opiate withdrawal responses.

Linalool attenuates acquisition and reinstatement and accelerates the extinction of nicotine-induced conditioned place preference in male mice

Background: Nicotine is the addictive agent in tobacco products. The monoterpene linalool is the main ingredient in the essential oils of various aromatic plants. It has previously been demonstrated that linalool has beneficial effects on some mechanisms that are important in drug addiction.Objectives: The goal of the current study was to investigate the effect of linalool on nicotine-induced conditioned place preference (CPP) in male mice.Methods: CPP was induced by administering intraperitoneal (i.p.) injection of nicotine (0.5 mg/kg) during the conditioning phase. The effects of nicotinic acetylcholine receptor partial agonist varenicline and linalool on the rewarding characteristics of nicotine were tested in mice with administration of linalool (12.5, 25, and 50 mg/kg, i.p.), varenicline (2 mg/kg, i.p.) or saline 30 minutes before nicotine injection. CPP was extinguished by repeated testing, during which conditioned mice were administered varenicline and linalool every day. One day after the last extinction trial, mice that received linalool, varenicline or saline 30 minutes before a priming injection of nicotine (0.1 mg/kg, i.p.) were immediately tested for reinstatement of CPP.Results: Linalool attenuated nicotine acquisition (50 mg/kg, p < .01) and reinstatement (25 and 50 mg/kg, respectively p < .05, p < .01) and accelerated the extinction of nicotine-induced CPP (50 mg/kg, p < .05). Linalool exhibited similar effects on the reference drug varenicline in the CPP phases.Conclusion: These results suggest that linalool may be helpful as an adjuvant for the treatment of nicotine use disorder.

Function and therapeutic potential of N-acyl amino acids

N-acyl amino acids (NAAs) are amphiphilic molecules, with different potential fatty acid and head group moieties. NAAs are the largest family of anandamide congener lipids discovered to date. In recent years, several NAAs have been identified as potential ligands, engaging novel binding sites and mechanisms for modulation of membrane proteins such as G-protein coupled receptors (GPRs), nuclear receptors, ion channels, and transporters. NAAs play a key role in a variety of physiological functions as lipid signaling molecules. Understanding the structure, function roles, and pharmacological potential of these NAAs is still in its infancy, and the biochemical roles are also mostly unknown. This review will provide a summary of the literature on NAAs and emphasize their therapeutic potential.

Endogenous opiates and behavior: 2019

This paper is the forty-second consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2019 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

N-Oleoylglycine and N-Oleoylalanine Do Not Modify Tolerance to Nociception, Hyperthermia, and Suppression of Activity Produced by Morphine

The endogenous amide N-Oleoylglycine (OlGly) and its analog N-Oleoylalanine (OlAla), have been shown to interfere with the affective and somatic responses to acute naloxone-precipitated MWD in male rats. Here we evaluated the potential of a single dose (5 mg/kg, ip) which alleviates withdrawal of these endogenous fatty acid amides to modify tolerance to anti-nociception, hyperthermia, and suppression of locomotion produced by morphine in male Sprague-Dawley rats. Although rats did develop tolerance to the hypolocomotor and analgesic effects of morphine, they did not develop tolerance to the hyperthermic effects of this substance. Administration of neither OlGly nor OlAla interfered with the establishment of morphine tolerance, nor did they modify behavioral responses elicited by morphine on any trial. These results suggest that the effects of OlGly and OlAla on opiate dependence may be limited to naloxone-precipitated withdrawal effects.

Relevance of Peroxisome Proliferator Activated Receptors in Multitarget Paradigm Associated with the Endocannabinoid System

Cannabinoids have shown to exert their therapeutic actions through a variety of targets. These include not only the canonical cannabinoid receptors CB1R and CB2R but also related orphan G protein-coupled receptors (GPCRs), ligand-gated ion channels, transient receptor potential (TRP) channels, metabolic enzymes, and nuclear receptors. In this review, we aim to summarize reported compounds exhibiting their therapeutic effects upon the modulation of CB1R and/or CB2R and the nuclear peroxisome proliferator-activated receptors (PPARs). Concomitant actions at CBRs and PPARα or PPARγ subtypes have shown to mediate antiobesity, analgesic, antitumoral, or neuroprotective properties of a variety of phytogenic, endogenous, and synthetic cannabinoids. The relevance of this multitargeting mechanism of action has been analyzed in the context of diverse pathologies. Synergistic effects triggered by combinatorial treatment with ligands that modulate the aforementioned targets have also been considered. This literature overview provides structural and pharmacological insights for the further development of dual cannabinoids for specific disorders.

Endocannabinoid-Like Lipid Neuromodulators in the Regulation of Dopamine Signaling: Relevance for Drug Addiction

The family of lipid neuromodulators has been rapidly growing, as the use of different -omics techniques led to the discovery of a large number of naturally occurring N-acylethanolamines (NAEs) and N-acyl amino acids belonging to the complex lipid signaling system termed endocannabinoidome. These molecules exert a variety of biological activities in the central nervous system, as they modulate physiological processes in neurons and glial cells and are involved in the pathophysiology of neurological and psychiatric disorders. Their effects on dopamine cells have attracted attention, as dysfunctions of dopamine systems characterize a range of psychiatric disorders, i.e., schizophrenia and substance use disorders (SUD). While canonical endocannabinoids are known to regulate excitatory and inhibitory synaptic inputs impinging on dopamine cells and modulate several dopamine-mediated behaviors, such as reward and addiction, the effects of other lipid neuromodulators are far less clear. Here, we review the emerging role of endocannabinoid-like neuromodulators in dopamine signaling, with a focus on non-cannabinoid N-acylethanolamines and their receptors. Mounting evidence suggests that these neuromodulators contribute to modulate synaptic transmission in dopamine regions and might represent a target for novel medications in alcohol and nicotine use disorder.

Oleoyl alanine (HU595): a stable monomethylated oleoyl glycine interferes with acute naloxone precipitated morphine withdrawal in male rats

RATIONALE

Oleoyl glycine, a little studied fatty acid amide similar in structure to anandamide, interferes with nicotine addiction in mice and acute naloxone-precipitated morphine withdrawal (MWD) in rats. Because endogenous oleoyl glycine is subject to rapid enzymatic deactivation, we evaluated the potential of more stable analogs to interfere with opiate withdrawal.

OBJECTIVES

The potential of monomethylated oleoyl glycine (oleoyl alanine, HU595) to interfere with somatic and aversive effects of acute naloxone-precipitated MWD, its duration, and mechanism of action was assessed in male Sprague Dawley rats. The potential of dimethylated oleoyl glycine (HU596) to interfere with the aversive effects of naloxone-precipitated MWD was also investigated.

RESULTS

Oleoyl alanine (HU595) interfered with somatic and aversive effects produced by naloxone-precipitated MWD at equivalent doses (1 and 5 mg/kg, i.p.) as we have reported for oleoyl glycine; however, oleoyl alanine produced a longer lasting (60 min) interference, yet did not produce rewarding or aversive effects on its own and did not modify locomotor activity. HU596 was not effective. The interference with aversive effects of naloxone-precipitated MWD by oleoyl alanine was prevented by both a PPARα antagonist and a CB₁ receptor antagonist. Accordingly, the compound was found to inhibit FAAH and activate PPARα in vitro. Finally, oleoyl alanine also reduced acute naloxone-precipitated MWD anhedonia, as measured by decreased saccharin preference.

CONCLUSIONS

Oleoyl alanine (also an endogenous fatty acid) may be a more stable and effective treatment for opiate withdrawal than oleoyl glycine.

Advances in smoking cessation pharmacotherapy: Non-nicotinic approaches in animal models

The landscape of worldwide tobacco use is changing, with a decrease in traditional smoking and an exponential rise in electronic cigarette use. No new nicotine cessation pharmacotherapies have come to market in the last 10 years. The current therapies that have been approved by the United States Food and Drug Administration for nicotine cessation include nicotine replacement therapy, varenicline, a nicotinic acetylcholine receptor partial agonist, and the atypical antidepressant bupropion. Nicotine replacement therapy and varenicline both act on nicotinic acetylcholine receptors. Bupropion inhibits the dopamine transporter, the norepinephrine transporter, and the nicotinic acetylcholine receptors to inhibit smoking behavior. Notwithstanding these treatments, rates of successful nicotine cessation in clinical trials remain low. Recent pharmacological approaches to improve nicotine cessation rates in animal models have turned their focus away from activating nicotinic acetylcholine receptors. The present review focuses on such pharmacological approaches, including nicotine vaccines, anti-nicotine antibodies, nicotine-degrading enzymes, cannabinoids, and metformin. Both immunopharmacological and enzymatic approaches rely on restricting and degrading nicotine within the periphery, thus preventing psychoactive effects of nicotine on the central nervous system. In contrast, pharmacologic inhibition of the enzymes which degrade nicotine could affect smoking behavior. Cannabinoid receptor agonists and antagonists interact with the dopamine reward pathway and show efficacy in reducing nicotine addiction-like behaviors in preclinical studies. Metformin is currently approved by the Food and Drug Administration for the treatment of diabetes. It activates specific intracellular kinases that may protect against the lower metabolism, higher oxidation, and inflammation that are associated with nicotine withdrawal. Further studies are needed to investigate non-nicotinic targets to improve the treatment of tobacco use disorder. This article is part of the special issue on 'Contemporary Advances in Nicotine Neuropharmacology'.

Cannabinoidomics - An analytical approach to understand the effect of medical Cannabis treatment on the endocannabinoid metabolome

Increasing evidence for the therapeutic potential of Cannabis in numerous pathological and physiological conditions has led to a surge of studies investigating the active compounds in different chemovars and their mechanisms of action, as well as their efficacy and safety. The biological effects of Cannabis have been attributed to phytocannabinoid modulation of the endocannabinoid system. In-vitro and in-vivo studies have shown that pure phytocannabinoids can alter the levels of endocannabinoids and other cannabimimetic lipids. However, it is not yet understood whether whole Cannabis extracts exert variable effects on the endocannabinoid metabolome, and whether these effects vary between tissues. To address these challenges, we have developed and validated a novel analytical approach, termed "cannabinoidomics," for the simultaneous extraction and analysis of both endogenous and plant cannabinoids from different biological matrices. In the methodological development liquid chromatography high resolution tandem mass spectrometry (LC/HRMS/MS) was used to identify 57 phytocannabinoids, 15 major phytocannabinoid metabolites, and 78 endocannabinoids and cannabimimetic lipids in different biological matrices, most of which have no analytical standards. In the validation process, spiked cannabinoids were quantified with acceptable selectivity, repeatability, reproducibility, sensitivity, and accuracy. The power of this analytical method is demonstrated by analysis of serum and four different sections of mouse brains challenged with three different cannabidiol (CBD)-rich extracts. The results demonstrate that variations in the minor phytocannabinoid contents of the different extracts may lead to varied effects on endocannabinoid concentrations, and on the CBD metabolite profile in the peripheral and central systems. We also show that the Cannabis challenge significantly decreases the levels of several endocannabinoids in specific brain sections compared to the control group. This effect is extract-specific and suggests the importance of minor, other-than CBD, phytocannabinoid or non-phytocannabinoid compounds.

Therapeutic Potential of Peroxisome Proliferator-Activated Receptor (PPAR) Agonists in Substance Use Disorders: A Synthesis of Preclinical and Human Evidence

Targeting peroxisome proliferator-activated receptors (PPARs) has received increasing interest as a potential strategy to treat substance use disorders due to the localization of PPARs in addiction-related brain regions and the ability of PPAR ligands to modulate dopamine neurotransmission. Robust evidence from animal models suggests that agonists at both the PPAR-α and PPAR-γ isoforms can reduce both positive and negative reinforcing properties of ethanol, nicotine, opioids, and possibly psychostimulants. A reduction in the voluntary consumption of ethanol following treatment with PPAR agonists seems to be the most consistent finding. However, the human evidence is limited in scope and has so far been less promising. There have been no published human trials of PPAR agonists for treatment of alcohol use disorder, despite the compelling preclinical evidence. Two trials of PPAR-α agonists as potential smoking cessation drugs found no effect on nicotine-related outcomes. The PPAR-γ agonist pioglitazone showed some promise in reducing heroin, nicotine, and cocaine craving in two human laboratory studies and one pilot trial, yet other outcomes were unaffected. Potential explanations for the discordance between the animal and human evidence, such as the potency and selectivity of PPAR ligands and sex-related variability in PPAR physiology, are discussed.

Protective Effects of N-Oleoylglycine in a Mouse Model of Mild Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the main causes of death in young people for which currently no efficacious treatment exists. Recently, we have reported that mice with mild-TBI with a specific injury in the insula showed elevated levels of a little investigated N-acyl amino acid, N-oleoylglycine (OlGly). N-acyl amino acids have recently experienced an increased interest because of their important biological activities. They belong to the endocannabinoidome family of lipids with structural similarities with the endocannabinoids (eCBs). The aim of this study was to test the neuroprotective and antihyperalgesic actions of OlGly in a model of mouse mild-TBI (mTBI) and its effect on levels of eCBs and N-acylethanolamines at the end of treatment. Following mTBI, mice were administered a daily injection of OlGly (10-50-100 mg/kg i.p.) for 14 days. Treatment with OlGly normalized motor impairment and behavior in the light/dark box test, ameliorated TBI-induced thermal hyperalgesia and mechanical allodynia, and normalized aggressiveness and depression. Moreover, levels of eCBs and some N-acylethanolamines underwent significant changes 60 days after TBI, especially in the prefrontal cortex and hypothalamus, and OlGly reversed some of these changes. In conclusion, our findings reveal that OlGly ameliorates the behavioral alterations associated with mTBI in mice, while concomitantly modulating eCB and eCB-like mediator tone.

Obesity Affects the Microbiota-Gut-Brain Axis and the Regulation Thereof by Endocannabinoids and Related Mediators

The hypothalamus regulates energy homeostasis by integrating environmental and internal signals to produce behavioral responses to start or stop eating. Many satiation signals are mediated by microbiota-derived metabolites coming from the gastrointestinal tract and acting also in the brain through a complex bidirectional communication system, the microbiota–gut–brain axis. In recent years, the intestinal microbiota has emerged as a critical regulator of hypothalamic appetite-related neuronal networks. Obesogenic high-fat diets (HFDs) enhance endocannabinoid levels, both in the brain and peripheral tissues. HFDs change the gut microbiota composition by altering the Firmicutes:Bacteroidetes ratio and causing endotoxemia mainly by rising the levels of lipopolysaccharide (LPS), the most potent immunogenic component of Gram-negative bacteria. Endotoxemia induces the collapse of the gut and brain barriers, interleukin 1β (IL1β)- and tumor necrosis factor α (TNFα)-mediated neuroinflammatory responses and gliosis, which alter the appetite-regulatory circuits of the brain mediobasal hypothalamic area delimited by the median eminence. This review summarizes the emerging state-of-the-art evidence on the function of the “expanded endocannabinoid (eCB) system” or endocannabinoidome at the crossroads between intestinal microbiota, gut-brain communication and host metabolism; and highlights the critical role of this intersection in the onset of obesity.

Acute naloxone-precipitated morphine withdrawal elicits nausea-like somatic behaviors in rats in a manner suppressed by N-oleoylglycine

RATIONALE

Acute naloxone-precipitated morphine withdrawal (MWD) produces a conditioned place aversion (CPA) in rats even after one or two exposures to high-dose (20 mg/kg, sc) morphine followed 24-h later by naloxone (1 mg/kg, sc). However, the somatic withdrawal reactions produced by acute naloxone-precipitated MWD in rats have not been investigated. A recently discovered fatty acid amide, N-oleoylglycine (OlGly), which has been suggested to act as a fatty acid amide hydrolase (FAAH) inhibitor and as a peroxisome proliferator-activated receptor alpha (PPARα) agonist, was previously shown to interfere with a naloxone-precipitated MWD-induced CPA in rats.

OBJECTIVES

The aims of these studies were to examine the somatic withdrawal responses produced by acute naloxone-precipitated MWD and determine whether OlGly can also interfere with these responses.

RESULTS

Here, we report that following two exposures to morphine (20 mg/kg, sc) each followed by naloxone (1 mg/kg, sc) 24 h later, rats display nausea-like somatic reactions of lying flattened on belly, abdominal contractions and diarrhea, and display increased mouthing movements and loss of body weight. OlGly (5 mg/kg, ip) interfered with naloxone-precipitated MWD-induced abdominal contractions, lying on belly, diarrhea and mouthing movements in male Sprague-Dawley rats, by both a cannabinoid 1 (CB₁) and a PPARα mechanism of action. Since these withdrawal reactions are symptomatic of nausea, we evaluated the potential of OlGly to interfere with lithium chloride (LiCl)-induced and MWD-induced conditioned gaping in rats, a selective measure of nausea; the suppression of MWD-induced gaping reactions by OlGly was both CB₁ and PPARα mediated.

CONCLUSION

These results suggest that the aversive effects of acute naloxone-precipitated MWD reflect nausea, which is suppressed by OlGly.

N-Acyl Amino Acids: Metabolism, Molecular Targets, and Role in Biological Processes

The lipid signal is becoming increasingly crowded as increasingly fatty acid amide derivatives are being identified and considered relevant therapeutic targets. The identification of N-arachidonoyl-ethanolamine as endogenous ligand of cannabinoid type-1 and type-2 receptors as well as the development of different–omics technologies have the merit to have led to the discovery of a huge number of naturally occurring N-acyl-amines. Among those mediators, N-acyl amino acids, chemically related to the endocannabinoids and belonging to the complex lipid signaling system now known as endocannabinoidome, have been rapidly growing for their therapeutic potential. Here, we review the current knowledge of the mechanisms for the biosynthesis and inactivation of the N-acyl amino acids, as well as the various molecular targets for some of the N-acyl amino acids described so far.

Beyond THC and Endocannabinoids

Research in the cannabinoid field, namely on phytocannabinoids, the endogenous cannabinoids anandamide and 2-arachidonoyl glycerol and their metabolizing and synthetic enzymes, the cannabinoid receptors, and anandamide-like cannabinoid compounds, has expanded tremendously over the last few years. Numerous endocannabinoid-like compounds have been discovered. The Cannabis plant constituent cannabidiol (CBD) was found to exert beneficial effects in many preclinical disease models ranging from epilepsy, cardiovascular disease, inflammation, and autoimmunity to neurodegenerative and kidney diseases and cancer. CBD was recently approved in the United States for the treatment of rare forms of childhood epilepsy. This has triggered the development of many CBD-based products for human use, often with overstated claims regarding their therapeutic effects. In this article, the recently published research on the chemistry and biological effects of plant cannabinoids (specifically CBD), endocannabinoids, certain long-chain fatty acid amides, and the variety of relevant receptors is critically reviewed.

Oleoyl glycine: interference with the aversive effects of acute naloxone-precipitated MWD, but not morphine reward, in male Sprague-Dawley rats

RATIONALE

Oleoyl glycine (OlGly), a recently discovered fatty acid amide that is structurally similar to N- acylethanolamines, which include the endocannabinoid, anandamide (AEA), as well as endogenous peroxisome proliferator-activated receptor alpha (PPARα) agonists oleoylethanolamide (OEA) and palmitoylethanolamide (PEA), has been shown to interfere with nicotine reward and dependence in mice.

OBJECTIVES AND METHODS

Behavioral and molecular techniques were used to investigate the ability of OlGly to interfere with the affective properties of morphine and morphine withdrawal (MWD) in male Sprague-Dawley rats.

RESULTS

Synthetic OlGly (1-30 mg/kg, intraperitoneal [ip]) produced neither a place preference nor aversion on its own; however, at doses of 1 and 5 mg/kg, ip, it blocked the aversive effects of MWD in a place aversion paradigm. This effect was reversed by the cannabinoid 1 (CB1) receptor antagonist, AM251 (1 mg/kg, ip), but not the PPARα antagonist, MK886 (1 mg/kg, ip). OlGly (5 or 30 mg/kg, ip) did not interfere with a morphine-induced place preference or reinstatement of a previously extinguished morphine-induced place preference. Ex vivo analysis of tissue (nucleus accumbens, amygdala, prefrontal cortex, and interoceptive insular cortex) collected from rats experiencing naloxone-precipitated MWD revealed that OlGly was selectively elevated in the nucleus accumbens. MWD did not modify levels of the endocannabinoids 2-AG and AEA, nor those of the PPARα ligands, OEA and PEA, in any region evaluated.

CONCLUSION

Here, we show that OlGly interferes with the aversive properties of acute naloxone-precipitated morphine withdrawal in rats. These results suggest that OlGly may reduce the impact of MWD and may possess efficacy in treating opiate withdrawal.

FAAH-Catalyzed C-C Bond Cleavage of a New Multitarget Analgesic Drug

The discovery of extended catalytic versatilities is of great importance in both the chemistry and biotechnology fields. Fatty acid amide hydrolase (FAAH) belongs to the amidase signature superfamily and is a major endocannabinoid inactivating enzyme using an atypical catalytic mechanism involving hydrolysis of amide and occasionally ester bonds. FAAH inhibitors are efficacious in experimental models of neuropathic pain, inflammation, and anxiety, among others. We report a new multitarget drug, AGN220653, containing a carboxyamide-4-oxazole moiety and endowed with efficacious analgesic and anti-inflammatory activities, which are partly due to its capability of achieving inhibition of FAAH, and subsequently increasing the tissue concentrations of the endocannabinoid anandamide. This inhibitor behaves as a noncompetitive, slowly reversible inhibitor. Autoradiography of purified FAAH incubated with AGN220653, opportunely radiolabeled, indicated covalent binding followed by fragmentation of the molecule. Molecular docking suggested a possible nucleophilic attack by FAAH-Ser241 on the carbonyl group of the carboxyamide-4-oxazole moiety, resulting in the cleavage of the C-C bond between the oxazole and the carboxyamide moieties, instead of either of the two available amide bonds. MRM-MS analyses only detected the Ser241-assisted formation of the carbamate intermediate, thus confirming the cleavage of the aforementioned C-C bond. Quantum mechanics calculations were fully consistent with this mechanism. The study exemplifies how FAAH structural features and mechanism of action may override the binding and reactivity propensities of substrates. This unpredicted mechanism could pave the way to the future development of a completely new class of amidase inhibitors, of potential use against pain, inflammation, and mood disorders.

Bioactive Lipids in Cancer, Inflammation and Related Diseases : Acute and Chronic Mild Traumatic Brain Injury Differentially Changes Levels of Bioactive Lipids in the CNS Associated with Headache

Headache is a common complaint after mild traumatic brain injury (mTBI). Changes in the CNS lipidome were previously associated with acrolein-induced headache in rodents. mTBI caused similar headache-like symptoms in rats; therefore, we tested the hypothesis that mTBI might likewise alter the lipidome. Using a stereotaxic impactor, rats were given either a single mTBI or a series of 4 mTBIs 48 h apart. 72 h later for single mTBI and 7 days later for repeated mTBI, the trigeminal ganglia (TG), trigeminal nucleus (TNC), and cerebellum (CER) were isolated. Using HPLC/MS/MS, ~80 lipids were measured in each tissue and compared to sham controls. mTBI drove widespread alterations in lipid levels. Single mTBI increased arachidonic acid and repeated mTBI increased prostaglandins in all 3 tissue types. mTBI affected multiple TRPV agonists, including N-arachidonoyl ethanolamine (AEA), which increased in the TNC and CER after single mTBI. After repeated mTBI, AEA increased in the TG, but decreased in the TNC. Common to all tissue types in single and repeated mTBI was an increase the AEA metabolite, N-arachidonoyl glycine, a potent activator of microglial migration. Changes in the CNS lipidome associated with mTBI likely play a role in headache and in long-term neurodegenerative effects of repeated mTBI.