Category Archives: Endocannabinoid System

Cannabinoid receptors in the inflammatory cells of canine atopic dermatitis

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Frontiers in Veterinary Science accepted into PubMed Central - Science & research news | Frontiers

“Background: Atopic dermatitis (AD) is one of the most common cutaneous inflammatory and pruritic diseases in dogs. Considering its multifactorial nature, AD can be a challenging disease to manage, and the therapeutic strategy must often be multimodal. In recent years, research has been moving toward the use of natural products which have beneficial effects on inflammation and itching, and no side effects. Cannabinoid receptors have been demonstrated to be expressed in healthy and diseased skin; therefore, one of the potential alternative therapeutic targets for investigating AD is the endocannabinoid system (ECS).

Objective: To immunohistochemically investigate the expression of the cannabinoid receptor type 2 (CB2R), and the cannabinoid-related receptors G protein-coupled receptor 55 (GPR55), transient receptor potential vanilloid 1 (TRPV1) and ankyrin 1 (TRPA1) in mast cells (MCs), macrophages, dendritic cells (DCs), T cells, and neutrophils of the skin of dogs with AD.

Animals: Samples of skin tissues were collected from eight dogs with AD (AD-dogs).

Materials and methods: The immunofluorescent stained cryosections of the skins of 8 dogs with AD having antibodies against CB2R, GPR55, TRPV1, TRPA1 were semiquantitatively evaluated. The inflammatory cells were identified using antibodies against tryptase (mast cells), ionized calcium binding adaptor molecule 1 (IBA1) (macrophages/DCs), CD3 (T cells), and calprotectin (neutrophils). The proportions of MCs, macrophages/DCs, T cells, and neutrophils expressing CB2R, GPR55, TRPV1 and TRPA1 were evaluated.

Results: The cells of the inflammatory infiltrate showed immunoreactivity (IR) for all or for some of the cannabinoid and cannabinoid-related receptors studied. In particular, MCs and macrophages/DCs showed CB2R-, GPR55-, TRPA1-, and TRPV1-IR; T cells showed CB2R-, GPR55- and TRPA1-IR, and neutrophils expressed GPR55-IR. Co-localization studies indicated that CB2R-IR was co-expressed with TRPV1-, TRPA1-, and GPR55-IR in different cellular elements of the dermis of the AD-dogs.

Conclusions and clinical importance: Cannabinoid receptor 2, and cannabinoid-related receptors GPR55, TRPV1 and TRPA1 were widely expressed in the inflammatory infiltrate of the AD-dogs. Based on the present findings, the ECS could be considered to be a potential therapeutic target for dogs with AD, and may mitigate itch and inflammation.”

https://pubmed.ncbi.nlm.nih.gov/36187821/

“The evidence regarding the effect of cannabinoid and cannabinoid-related receptors on MCs, macrophages and DCs (CB2R, GPR55, TRPV1, TRPA1), T-cells (CB2R, GPR55, TRPA1), and on neutrophils (GPR55) suggests the possibility that the manipulation of the inflammatory cell functions with endocannabinoids and cannabinoids could result in a novel approach to the treatment of AD. Phytocannabinoids could potentially modulate inflammatory responses by regulating more than one underlying mechanism (inflammatory cells, keratinocytes, sensory nerves, fibroblasts, etc.).”

https://www.frontiersin.org/articles/10.3389/fvets.2022.987132/full

Changes in the expression of endocannabinoid system components in an experimental model of chemotherapy-induced peripheral neuropathic pain: Evaluation of sex-related differences

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Experimental Neurology

“Chemotherapy-induced neuropathic pain is a serious clinical problem and one of the major side effects in cancer treatment. The endocannabinoid system (ECS) plays a crucial role in regulating pain neurotransmission, and changes in the expression of different components of the ECS have been reported in experimental models of persistent pain. In addition, sex differences have been observed in ECS regulation and function. The aim of our study was to evaluate whether administration of oxaliplatin, a neurotoxic antineoplastic agent, induced changes in the expression of ECS components in peripheral and central stations of the pain pathway, and if those changes exhibited sexual dimorphism. Adult male and female rats were injected with oxaliplatin or saline, and mechanical and cold hypersensitivity and allodynia were evaluated using Von Frey and Choi Tests. The mRNA levels corresponding to cannabinoid receptors (CB1, CB2), cannabinoid-related receptors (GPR55, 5HT1A, TRPV1) and to the main enzymes involved in the synthesis (DAGL, DAGL, NAPE-PLD) and degradation (MGL, FAAH) of endocannabinoids were assessed in lumbar dorsal root ganglia (DRGs) and spinal cord by using real time RT-PCR. In addition, the levels of the main endocannabinoids, 2-arachidonoylglycerol (2-AG) and anandamide (AEA), were evaluated using commercial ELISA kits. Oxaliplatin administration induced the development of mechanical and cold hypersensitivity and allodynia in male and female animals. Oxaliplatin also induced early and robust changes in the expression of several components of the ECS in DRGs. A marked upregulation of CB1, CB2, 5HT1A and TRPV1 was detected in both sexes. Interestingly, while DAGL mRNA levels remained unchanged, DAGL was downregulated in male and upregulated in female rats. Finally, MGL and NAPE-PLD showed increased levels only in male animals, while FAAH resulted upregulated in both sexes. In parallel, reduced 2-AG and AEA levels were detected in DRGs from male or female rats, respectively. In the lumbar spinal cord, only TRPV1 mRNA levels were found to be upregulated in both sexes. Our results reveal previously unreported changes in the expression of cannabinoid receptors, ligands and enzymes occurring mainly in the peripheral nervous system and displaying certain sexual dimorphism. These changes may contribute to the physiopathology of oxaliplatin-induced neuropathic pain in male and female rats. A better understanding of these dynamic changes will facilitate the development of mechanism- and sex-specific approaches to optimize the use of cannabinoid-based medicines for the treatment of chemotherapy-induced pain.”

https://pubmed.ncbi.nlm.nih.gov/36179876/

https://www.sciencedirect.com/science/article/abs/pii/S0014488622002576?via%3Dihub

Expression of cannabinoid receptors CB1 and CB2 in canine cutaneous mast cell tumours

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Research in Veterinary Science

“Cannabinoid receptors (CB1 and CB2) belong to endocannabinoid system (ECS), which is also composed from endocannabinoids and the enzymatic systems involved in their biosynthesis and degradation. The expression of CB1 and CB2 have been previously identified in normal canine mast cell and in atopic dermatitis. Canine cutaneous mast cell tumours (cMCTs) are among the most common cutaneous neoplasms in dogs and have a highly variable clinical behaviour. Expression of CB1-CB2 was assessed by means of immunohistochemistry in thirty-seven dogs (from 2019 to 2021) with proven histological diagnosis of cMCT. Dogs were divided in two groups according to the Kiupel’s grading system: high-grade (HG) cMCT and low-grade (LG) cMCT. A semiquantitative (score 0-3) and quantitative assessment of immunoreactivity (IR) was performed for each case. Our results show that there CB1 and CB2 are highly expressed in LG- cMCT, in contrast to HG- cMCT.”

https://pubmed.ncbi.nlm.nih.gov/36179546/

https://www.sciencedirect.com/science/article/abs/pii/S0034528822002946?via%3Dihub

Effects of β-caryophyllene, A dDietary Cannabinoid, in Animal Models of Drug Addiction

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“Background: β-caryophyllene (BCP) is a natural bicyclic sesquiterpene found in Cannabis and other plants. BCP is currently used as a food additive, although pharmacological studies suggest its potential therapeutic application for the treatment of certain brain disorders. The mechanisms of action of BCP remain uncertain, possibly including full agonism at the cannabinoid CB 2 receptor (CB 2 R).

Objective: The study aims to investigate the BCP’s potential as a new drug for the treatment of substance use disorders, by reviewing preclinical studies with animal models.

Results: BCP has been investigated in behavioral paradigms, including drug self-administration, conditioned place preference, and intracranial self-stimulation; the drugs tested were cocaine, nicotine, alcohol, and methamphetamine. Remarkably, BCP prevented or reversed behavioral changes resulting from drug exposure. As expected, the mechanism of action entails CB 2 R activation, although this is unlikely to constitute the only molecular target to explain such effects. Another potential target is the peroxisome proliferator-activated receptor.

Conclusion: Preclinical studies report promising results with BCP in animal models of substance use disorders. Further research, including studies in humans, are warranted to establish its therapeutic potential and its mechanisms of action.”

https://pubmed.ncbi.nlm.nih.gov/36173065/

https://www.eurekaselect.com/article/126579

The role of cannabinoids in neurodevelopmental disorders of children and adolescents

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PubMed | MIT Libraries News

“Introduction: Neurodevelopmental disorders have a multifactorial etiology that results from the interaction between biological and environmental factors. The biological basis of many of these disorders is only partially understood, which makes therapeutic interventions, especially pharmacological ones, particularly difficult. The impact of medical cannabis on neurological and psychiatric disorders has been studied for a long time. This study aimed to review the currently available clinical and pre-clinical studies regarding the use of cannabinoids in pediatric neurodevelopmental disorders and to draw attention to the potential therapeutic role of cannabidiol in this field.

Development: Cannabidiol is an endocannabinoid system modulator and exerts its effects on both developing and mature brains through numerous mechanisms. Cannabidiol holds a relatively high toxicity limit and current literature suggests that it may have anxiolytic, antipsychotic, and neuroprotective properties. Clinical evidence suggests that early treatment with cannabidiol might be a promising therapy for neurodevelopmental disorders, including intellectual disability, autism spectrum disorders, tics, and attention/deficit hyperactivity disorder.

Conclusions: This review hopefully draws attention to an emerging body of evidence concerning cannabidiol’s significant potential to safely improve many of the common symptoms affecting children and adolescents with neurodevelopmental disorders, especially autism spectrum disorder.”

https://pubmed.ncbi.nlm.nih.gov/36169325/

Targeting the endocannabinoid system for the treatment of abdominal pain in irritable bowel syndrome

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Nature Reviews Gastroenterology & Hepatology

“The management of visceral pain in patients with disorders of gut-brain interaction, notably irritable bowel syndrome, presents a considerable clinical challenge, with few available treatment options.

Patients are increasingly using cannabis and cannabinoids to control abdominal pain. Cannabis acts on receptors of the endocannabinoid system, an endogenous system of lipid mediators that regulates gastrointestinal function and pain processing pathways in health and disease.

The endocannabinoid system represents a logical molecular therapeutic target for the treatment of pain in irritable bowel syndrome.

Here, we review the physiological and pathophysiological functions of the endocannabinoid system with a focus on the peripheral and central regulation of gastrointestinal function and visceral nociception. We address the use of cannabinoids in pain management, comparing them to other treatment modalities, including opioids and neuromodulators. Finally, we discuss emerging therapeutic candidates targeting the endocannabinoid system for the treatment of pain in irritable bowel syndrome.”

https://pubmed.ncbi.nlm.nih.gov/36168049/

https://www.nature.com/articles/s41575-022-00682-y

Endocannabinoid-Binding Receptors as Drug Targets

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“Cannabis plant has been used from ancient times with therapeutic purposes for treating human pathologies, but the identification of the cellular and molecular mechanisms underlying the therapeutic properties of the phytocannabinoids, the active compounds in this plant, occurred in the last years of the past century.

In the late 1980s and early 1990s, seminal studies demonstrated the existence of cannabinoid receptors and other elements of the so-called endocannabinoid system. These G protein-coupled receptors (GPCRs) are a key element in the functions assigned to endocannabinoids and appear to serve as promising pharmacological targets. They include CB1, CB2, and GPR55, but also non-GPCRs can be activated by endocannabinoids, like ionotropic receptor TRPV1 and even nuclear receptors of the PPAR family.

Their activation, inhibition, or simply modulation have been associated with numerous physiological effects at both central and peripheral levels, which may have therapeutic value in different human pathologies, then providing a solid experimental explanation for both the ancient medicinal uses of Cannabis plant and the recent advances in the development of cannabinoid-based specific therapies.

This chapter will review the scientific knowledge generated in the last years around the research on the different endocannabinoid-binding receptors and their signaling mechanisms. Our intention is that this knowledge may help readers to understand the relevance of these receptors in health and disease conditions, as well as it may serve as the theoretical basis for the different experimental protocols to investigate these receptors and their signaling mechanisms that will be described in the following chapters.”

https://pubmed.ncbi.nlm.nih.gov/36152178/

https://link.springer.com/protocol/10.1007/978-1-0716-2728-0_6

Endocannabinoid Metabolism and Transport as Drug Targets

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Book cover

“The wide distribution of the endocannabinoid system (ECS) throughout the body and its pivotal pathophysiological role offer promising opportunities for the development of novel therapeutic drugs for treating several diseases. However, the need for strategies to circumvent the unwanted psychotropic and immunosuppressive effects associated with cannabinoid receptor agonism/antagonism has led to considerable research in the field of molecular alternatives, other than type-1 and type-2 (CB1/2) receptors, as therapeutic targets to indirectly manipulate this pro-homeostatic system. In this context, the use of selective inhibitors of proteins involved in endocannabinoid (eCB) transport and metabolism allows for an increase or decrease of the levels of N-arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG) in the sites where these major eCBs are indeed needed. This chapter will briefly review some preclinical and clinical evidence for the therapeutic potential of ECS pharmacological manipulation.”

https://pubmed.ncbi.nlm.nih.gov/36152188/

https://link.springer.com/protocol/10.1007/978-1-0716-2728-0_16


Dynamic Changes in the Endocannabinoid System during the Aging Process: Focus on the Middle-Age Crisis

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ijms-logo

“Endocannabinoid (eCB) signaling is markedly decreased in the hippocampus (Hip) of aged mice, and the genetic deletion of the cannabinoid receptor type 1 (CB1) leads to an early onset of cognitive decline and age-related histological changes in the brain. Thus, it is hypothesized that cognitive aging is modulated by eCB signaling through CB1.

In the present study, we detailed the changes in the eCB system during the aging process using different complementary techniques in mouse brains of five different age groups, ranging from adolescence to old age.

Our findings indicate that the eCB system is most strongly affected in middle-aged mice (between 9 and 12 months of age) in a brain region-specific manner. We show that 2-arachidonoylglycerol (2-AG) was prominently decreased in the Hip and moderately in caudate putamen (CPu), whereas anandamide (AEA) was decreased in both CPu and medial prefrontal cortex along with cingulate cortex (mPFC+Cg), starting from 6 months until 12 months. Consistent with the changes in 2-AG, the 2-AG synthesizing enzyme diacylglycerol lipase α (DAGLα) was also prominently decreased across the sub-regions of the Hip.

Interestingly, we found a transient increase in CB1 immunoreactivity across the sub-regions of the Hip at 9 months, a plausible compensation for reduced 2-AG, which ultimately decreased strongly at 12 months. Furthermore, quantitative autoradiography of CB1 revealed that [3H]CP55940 binding markedly increased in the Hip at 9 months. However, unlike the protein levels, CB1 binding density did not drop strongly at 12 months and at old age. Furthermore, [3H]CP55940 binding was significantly increased in the lateral entorhinal cortex (LEnt), starting from the middle age until the old age.

Altogether, our findings clearly indicate a middle-age crisis in the eCB system, which could be a potential time window for therapeutic interventions to abrogate the course of cognitive aging.”

https://pubmed.ncbi.nlm.nih.gov/36142165/

“In conclusion, our observations indicate that the eCB system is most affected during the middle age in a brain region-specific manner. Taken together, the middle-age crisis in the eCB signaling corresponds well with the onset of neuroinflammatory glial activity and cognitive deficits in mice. We now hypothesize that late middle-age is the time period when a therapy based on the activation of the cannabinoid system has the highest efficacy to prevent cognitive aging and pathologies related to brain aging.”

https://www.mdpi.com/1422-0067/23/18/10254/htm

Cannabinoid signaling and risk in Huntington’s disease

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Frontiers announces its first partnership with a leading Chinese University | STM Publishing News

“Dysregulated endocannabinoid (eCB) signaling and the loss of cannabinoid receptors (CB1Rs) are important phenotypes of Huntington’s disease (HD) but the precise contribution that eCB signaling has at the circuit level is unknown. Using a computational model of spiking neurons, synapses, and eCB signaling, we demonstrate that eCB signaling functions as a homeostatic control mechanism, minimizing excess glutamate. Furthermore, our model demonstrates that metabolic risk, quantified by excess glutamate, increases with cortico-striatal long-term depression (LTD) and/or increased cortico-striatal activity, and replicates a progressive loss of cannabinoid receptors on inhibitory terminals as a function of the excitatory/inhibitory ratio.”

https://pubmed.ncbi.nlm.nih.gov/36118134/

https://www.frontiersin.org/articles/10.3389/fncom.2022.903947/full