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Cui Sun M, Otálora-Alcaraz A, Prenderville JA, Downer EJ. Toll-like receptor signalling as a cannabinoid target. Biochem Pharmacol 2024; 222:116082. [PMID: 38438052 DOI: 10.1016/j.bcp.2024.116082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 02/01/2024] [Accepted: 02/22/2024] [Indexed: 03/06/2024]
Abstract
Toll-like receptors (TLRs) have become a focus in biomedicine and biomedical research given the roles of this unique family of innate immune proteins in immune activation, infection, and autoimmunity. It is evident that TLR dysregulation, and subsequent alterations in TLR-mediated inflammatory signalling, can contribute to disease pathogenesis, and TLR targeted therapies are in development. This review highlights evidence that cannabinoids are key regulators of TLR signalling. Cannabinoids include component of the plant Cannabis sativa L. (C. sativa), synthetic and endogenous ligands, and overall represent a class of compounds whose therapeutic potential and mechanism of action continues to be elucidated. Cannabinoid-based medicines are in the clinic, and are furthermore under intense investigation for broad clinical development to manage symptoms of a range of disorders. In this review, we present an overview of research evidence that signalling linked to a range of TLRs is targeted by cannabinoids, and such cannabinoid mediated effects represent therapeutic avenues for further investigation. First, we provide an overview of TLRs, adaptors and key signalling events, alongside a summary of evidence that TLRs are linked to disease pathologies. Next, we discuss the cannabinoids system and the development of cannabinoid-based therapeutics. Finally, for the bulk of this review, we systematically outline the evidence that cannabinoids (plant-derived cannabinoids, synthetic cannabinoids, and endogenous cannabinoid ligands) can cross-talk with innate immune signalling governed by TLRs, focusing specifically on each member of the TLR family. Cannabinoids should be considered as key regulators of signalling controlled by TLRs, and such regulation should be a major focus in terms of the anti-inflammatory propensity of the cannabinoid system.
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Affiliation(s)
- Melody Cui Sun
- Discipline of Physiology, School of Medicine, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Almudena Otálora-Alcaraz
- Discipline of Physiology, School of Medicine, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Jack A Prenderville
- Discipline of Physiology, School of Medicine, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland; Transpharmation Ireland Limited, Institute of Neuroscience, Trinity College, Dublin 2, Ireland
| | - Eric J Downer
- Discipline of Physiology, School of Medicine, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland.
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2
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Swindell WR, Bojanowski K, Singh P, Randhawa M, Chaudhuri RK. Bakuchiol and ethyl (linoleate/oleate) synergistically modulate endocannabinoid tone in keratinocytes and repress inflammatory pathway mRNAs. JID Innovations 2022; 3:100178. [PMID: 36992949 PMCID: PMC10041561 DOI: 10.1016/j.xjidi.2022.100178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 09/23/2022] [Accepted: 10/20/2022] [Indexed: 12/27/2022] Open
Abstract
The endocannabinoid (eCB) system plays an active role in epidermal homeostasis. Phytocannabinoids such as cannabidiol modulate this system but also act through eCB-independent mechanisms. This study evaluated the effects of cannabidiol, bakuchiol (BAK), and ethyl (linoleate/oleate) (ELN) in keratinocytes and reconstituted human epidermis. Molecular docking simulations showed that each compound binds the active site of the eCB carrier FABP5. However, BAK and ethyl linoleate bound this site with the highest affinity when combined 1:1 (w/w), and in vitro assays showed that BAK + ELN most effectively inhibited FABP5 and fatty acid amide hydrolase. In TNF-stimulated keratinocytes, BAK + ELN reversed TNF-induced expression shifts and uniquely downregulated type I IFN genes and PTGS2 (COX2). BAK + ELN also repressed expression of genes linked to keratinocyte differentiation but upregulated those associated with proliferation. Finally, BAK + ELN inhibited cortisol secretion in reconstituted human epidermis skin (not observed with cannabidiol). These results support a model in which BAK and ELN synergistically interact to inhibit eCB degradation, favoring eCB mobilization and inhibition of downstream inflammatory mediators (e.g., TNF, COX-2, type I IFN). A topical combination of these ingredients may thus enhance cutaneous eCB tone or potentiate other modulators, suggesting novel ways to modulate the eCB system for innovative skincare product development.
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Affiliation(s)
- William R. Swindell
- Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
- Correspondence: William R. Swindell, Department of Internal Medicine, UT Southwestern Medical Center, 5959 Harry Hines Boulevard, Ste 7.700, Dallas, Texas 75390-9175, USA.
| | | | - Parvesh Singh
- School of Chemistry & Physics, University of KwaZulu-Natal, Westville, South Africa
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Reusch N, Ravichandran KA, Olabiyi BF, Komorowska-Müller JA, Hansen JN, Ulas T, Beyer M, Zimmer A, Schmöle AC. Cannabinoid receptor 2 is necessary to induce toll-like receptor-mediated microglial activation. Glia 2021; 70:71-88. [PMID: 34499767 DOI: 10.1002/glia.24089] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 01/17/2023]
Abstract
The tight regulation of microglia activity is key for precise responses to potential threats, while uncontrolled and exacerbated microglial activity is neurotoxic. Microglial toll-like receptors (TLRs) are indispensable for sensing different types of assaults and triggering an innate immune response. Cannabinoid receptor 2 (CB2) signaling is a key pathway to control microglial homeostasis and activation, and its activation is connected to changes in microglial activity. We aimed to investigate how CB2 signaling impacts TLR-mediated microglial activation. Here, we demonstrate that deletion of CB2 causes a dampened transcriptional response to prototypic TLR ligands in microglia. Loss of CB2 results in distinct microglial gene expression profiles, morphology, and activation. We show that the CB2-mediated attenuation of TLR-induced microglial activation is mainly p38 MAPK-dependent. Taken together, we demonstrate that CB2 expression and signaling are necessary to fine-tune TLR-induced activation programs in microglia.
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Affiliation(s)
- Nico Reusch
- Systems Medicine, German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Genomics and Immunoregulation, Life and Medical Sciences Institute (LIMES), Bonn, Germany
| | | | | | - Joanna Agnieszka Komorowska-Müller
- Institute for Molecular Psychiatry, Medical Faculty, University of Bonn, Bonn, Germany.,International Max Planck Research School for Brain and Behavior, University of Bonn, Bonn, Germany
| | - Jan N Hansen
- Institute of Innate Immunity, Biophysical Imaging, Medical Faculty, University of Bonn, Bonn, Germany
| | - Thomas Ulas
- Systems Medicine, German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Genomics and Immunoregulation, Life and Medical Sciences Institute (LIMES), Bonn, Germany.,Platform for Single Cell Genomics and Epigenomics (PRECISE), German Center for Neurodegenerative Diseases (DZNE), University of Bonn, Bonn, Germany
| | - Marc Beyer
- Platform for Single Cell Genomics and Epigenomics (PRECISE), German Center for Neurodegenerative Diseases (DZNE), University of Bonn, Bonn, Germany.,Molecular Immunology in Neurodegeneration, German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Andreas Zimmer
- Institute for Molecular Psychiatry, Medical Faculty, University of Bonn, Bonn, Germany
| | - Anne-Caroline Schmöle
- Institute for Molecular Psychiatry, Medical Faculty, University of Bonn, Bonn, Germany
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4
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Posillico CK, Garcia-Hernandez RE, Tronson NC. Sex differences and similarities in the neuroimmune response to central administration of poly I:C. J Neuroinflammation 2021; 18:193. [PMID: 34488804 PMCID: PMC8418962 DOI: 10.1186/s12974-021-02235-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 08/04/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The neuroimmune system is required for normal neural processes, including modulation of cognition, emotion, and adaptive behaviors. Aberrant neuroimmune activation is associated with dysregulation of memory and emotion, though the precise mechanisms at play are complex and highly context dependent. Sex differences in neuroimmune activation and function further complicate our understanding of its roles in cognitive and affective regulation. METHODS Here, we characterized the physiological sickness and inflammatory response of the hippocampus following intracerebroventricular (ICV) administration of a synthetic viral mimic, polyinosinic:polycytidylic acid (poly I:C), in both male and female C57Bl/6N mice. RESULTS We observed that poly I:C induced weight loss, fever, and elevations of cytokine and chemokines in the hippocampus of both sexes. Specifically, we found transient increases in gene expression and protein levels of IL-1α, IL-1β, IL-4, IL-6, TNFα, CCL2, and CXCL10, where males showed a greater magnitude of response compared with females. Only males showed increased IFNα and IFNγ in response to poly I:C, whereas both males and females exhibited elevations of IFNβ, demonstrating a specific sex difference in the anti-viral response in the hippocampus. CONCLUSION Our data suggest that type I interferons are one potential node mediating sex-specific cytokine responses and neuroimmune effects on cognition. Together, these findings highlight the importance of using both males and females and analyzing a broad set of inflammatory markers in order to identify the precise, sex-specific roles for neuroimmune dysregulation in neurological diseases and disorders.
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Affiliation(s)
- Caitlin K Posillico
- Psychology Department, University of Michigan, 530 Church St., Ann Arbor, MI 48109, USA
| | | | - Natalie C Tronson
- Psychology Department, University of Michigan, 530 Church St., Ann Arbor, MI 48109, USA.
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Flannery LE, Kerr DM, Hughes EM, Kelly C, Costello J, Thornton AM, Humphrey RM, Finn DP, Roche M. N-acylethanolamine regulation of TLR3-induced hyperthermia and neuroinflammatory gene expression: A role for PPARα. J Neuroimmunol 2021; 358:577654. [PMID: 34265624 PMCID: PMC8243641 DOI: 10.1016/j.jneuroim.2021.577654] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/11/2021] [Accepted: 06/28/2021] [Indexed: 12/12/2022]
Abstract
Increasing evidence suggests that SARS-CoV-2, the virus responsible for the COVID-19 pandemic, is associated with increased risk of developing neurological or psychiatric conditions such as depression, anxiety or dementia. While the precise mechanism underlying this association is unknown, aberrant activation of toll-like receptor (TLR)3, a viral recognizing pattern recognition receptor, may play a key role. Synthetic cannabinoids and enhancing cannabinoid tone via inhibition of fatty acid amide hydrolase (FAAH) has been demonstrated to modulate TLR3-induced neuroimmune responses and associated sickness behaviour. However, the role of individual FAAH substrates, and the receptor mechanisms mediating these effects, are unknown. The present study examined the effects of intracerebral or systemic administration of the FAAH substrates N-oleoylethanolamide (OEA), N-palmitoylethanolamide (PEA) or the anandamide (AEA) analogue meth-AEA on hyperthermia and hypothalamic inflammatory gene expression following administration of the TLR3 agonist, and viral mimetic, poly I:C. The data demonstrate that meth-AEA does not alter TLR3-induced hyperthermia or hypothalamic inflammatory gene expression. In comparison, OEA and PEA attenuated the TLR3-induced hyperthermia, although only OEA attenuated the expression of hyperthermia-related genes (IL-1β, iNOS, COX2 and m-PGES) in the hypothalamus. OEA, but not PEA, attenuated TLR3-induced increases in the expression of all IRF- and NFκB-related genes examined in the hypothalamus, but not in the spleen. Antagonism of PPARα prevented the OEA-induced attenuation of IRF- and NFκB-related genes in the hypothalamus following TLR3 activation but did not significantly alter temperature. PPARα agonism did not alter TLR3-induced hyperthermia or hypothalamic inflammatory gene expression. These data indicate that OEA may be the primary FAAH substrate that modulates TLR3-induced neuroinflammation and hyperthermia, effects partially mediated by PPARα.
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Affiliation(s)
- Lisa E Flannery
- Physiology, National University of Ireland, Galway, Ireland; Centre for Pain Research and Galway Neuroscience Centre, National University of Ireland, Galway, Ireland
| | - Daniel M Kerr
- Pharmacology and Therapeutics, School of Medicine, National University of Ireland, Galway, Ireland; Centre for Pain Research and Galway Neuroscience Centre, National University of Ireland, Galway, Ireland
| | - Edel M Hughes
- Physiology, National University of Ireland, Galway, Ireland
| | - Colm Kelly
- Physiology, National University of Ireland, Galway, Ireland
| | | | | | - Rachel M Humphrey
- Physiology, National University of Ireland, Galway, Ireland; Centre for Pain Research and Galway Neuroscience Centre, National University of Ireland, Galway, Ireland
| | - David P Finn
- Pharmacology and Therapeutics, School of Medicine, National University of Ireland, Galway, Ireland; Centre for Pain Research and Galway Neuroscience Centre, National University of Ireland, Galway, Ireland
| | - Michelle Roche
- Physiology, National University of Ireland, Galway, Ireland; Centre for Pain Research and Galway Neuroscience Centre, National University of Ireland, Galway, Ireland.
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Thornton AM, Humphrey RM, Kerr DM, Finn DP, Roche M. Increasing Endocannabinoid Tone Alters Anxiety-Like and Stress Coping Behaviour in Female Rats Prenatally Exposed to Valproic Acid. Molecules 2021; 26:molecules26123720. [PMID: 34207178 PMCID: PMC8233839 DOI: 10.3390/molecules26123720] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 06/14/2021] [Accepted: 06/15/2021] [Indexed: 12/13/2022] Open
Abstract
Given the sex differences evident in the prevalence of autism, there is an increased awareness of the importance of including females in autism research to determine sexual dimorphism and sex-specific treatments. Cannabinoids and endocannabinoid modulators have been proposed as potential novel treatments for autism-related symptoms; however, few studies to date have examined if these pharmacological agents elicit sex-specific effects. The aim of the present study was to use the valproic acid (VPA) model of autism to compare the behavioural responses of male and female rats and examine the effects of increasing endocannabinoid tone on the behavioural responses of VPA-exposed female rats. These data revealed that VPA-exposed male, but not female, rats exhibit reduced social responding in the three-chamber and olfactory habituation/dishabituation (OHD) test during adolescence. In comparison, VPA-exposed female, but not male, adolescent rats exhibited anxiety-like behaviour in the elevated plus maze (EPM) and open field test (OFT). In VPA-exposed female rats, increasing 2-AG levels augmented anxiety-like behaviour in the EPM and OFT, while increasing AEA levels reduced stress coping behaviour in the swim stress test. These data highlight sexual dimorphic behaviours in the VPA model and indicate that enhancing endocannabinoid levels may exacerbate negative affective behaviour in VPA-exposed females. Thus, considerations should be paid to the possible sex-specific effects of cannabinoids for the treatment of symptoms associated with autism.
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Affiliation(s)
- Aoife M. Thornton
- Physiology, School of Medicine, National University of Ireland Galway, H91 W5P7 Galway, Ireland; (A.M.T.); (R.M.H.)
- Galway Neuroscience Centre, National University of Ireland Galway, H91 W5P7 Galway, Ireland;
| | - Rachel M. Humphrey
- Physiology, School of Medicine, National University of Ireland Galway, H91 W5P7 Galway, Ireland; (A.M.T.); (R.M.H.)
- Galway Neuroscience Centre, National University of Ireland Galway, H91 W5P7 Galway, Ireland;
- Centre for Pain Research, National University of Ireland Galway, H91 W5P7 Galway, Ireland
| | - Daniel M. Kerr
- Pharmacology and Therapeutics, School of Medicine, National University of Ireland Galway, H91 W5P7 Galway, Ireland;
| | - David P. Finn
- Galway Neuroscience Centre, National University of Ireland Galway, H91 W5P7 Galway, Ireland;
- Centre for Pain Research, National University of Ireland Galway, H91 W5P7 Galway, Ireland
- Pharmacology and Therapeutics, School of Medicine, National University of Ireland Galway, H91 W5P7 Galway, Ireland;
| | - Michelle Roche
- Physiology, School of Medicine, National University of Ireland Galway, H91 W5P7 Galway, Ireland; (A.M.T.); (R.M.H.)
- Galway Neuroscience Centre, National University of Ireland Galway, H91 W5P7 Galway, Ireland;
- Centre for Pain Research, National University of Ireland Galway, H91 W5P7 Galway, Ireland
- Correspondence:
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7
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Komorowska-Müller JA, Schmöle AC. CB2 Receptor in Microglia: The Guardian of Self-Control. Int J Mol Sci 2020; 22:E19. [PMID: 33375006 DOI: 10.3390/ijms22010019] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 12/16/2020] [Accepted: 12/18/2020] [Indexed: 12/12/2022] Open
Abstract
Microglia are key to maintaining the homeostasis of the brain. These immune cells of the brain can be our biggest ally in fighting infections, but can worsen pathology or hinder recovery when uncontrolled. Thus, understanding how microglia contribute to neuroinflammatory processes and how their activity can be controlled is of great importance. It is known that activation of endocannabinoid system, and especially the cannabinoid type 2 receptor (CB2R), decreases inflammation. Alongside its non-psychoactive effect, it makes the CB2R receptor a perfect target for treating diseases accompanied by neuroinflammation including neurodegenerative diseases. However, the exact mechanisms by which CB2R regulates microglial activity are not yet understood. Here, we review the current knowledge on the roles of microglial CB2R from in vitro and in vivo studies. We look into CB2R function under physiological and pathological conditions and focus on four different disease models representing chronic and acute inflammation. We highlight open questions and controversies and provide an update on the latest discoveries that were enabled by the development of novel technologies. Also, we discuss the recent findings on the role of microglia CB2R in cognition and its role in neuron–microglia communication.
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Abstract
Toll-like receptors (TLRs) play an important role in the innate immune system, and recently, they have been shown to be involved in the regulation of blood pressure. The incidence of hypertension is higher in men, and it increases in postmenopausal women. In fact, premenopausal women are protected from cardiovascular disease compared with age-matched men, and it is well established that this protective effect is lost with menopause. However, the molecular mechanisms underlying this protection in women are unknown. Whether or not it could be related to differential activation of the innate immune system remains to be elucidated. This review focuses on (1) the differences between men and women in TLR activation and (2) whether TLR activation may influence the regulation of blood pressure in a sex-dependent manner.
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Affiliation(s)
- Vanessa Dela Justina
- Graduate Program in Biological Sciences, Federal University of Goiás, Goiânia, Brazil
| | - Fernanda R. Giachini
- Graduate Program in Biological Sciences, Federal University of Goiás, Goiânia, Brazil
- Institute of Health Sciences and Health, Universidad Federal De Mato Grosso, Barra Do Garcas, Brazil
| | - Jennifer C. Sullivan
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, GA
| | - R. Clinton Webb
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, GA
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Killilea M, Kerr DM, Mallard BM, Roche M, Wheatley AM. Exacerbated LPS/GalN-Induced Liver Injury in the Stress-Sensitive Wistar Kyoto Rat Is Associated with Changes in the Endocannabinoid System. Molecules 2020; 25:E3834. [PMID: 32842550 DOI: 10.3390/molecules25173834] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 08/14/2020] [Accepted: 08/20/2020] [Indexed: 02/08/2023] Open
Abstract
Acute liver injury (ALI) is a highly destructive and potentially life-threatening condition, exacerbated by physical and psychological stress. The endocannabinoid system plays a key role in modulating stress and hepatic function. The aim of this study was to examine the development of acute liver injury in the genetically susceptible stress-sensitive Wistar-Kyoto (WKY) rat compared with normo-stress-sensitive Sprague Dawley (SD) rats, and associated changes in the endocannabinoid system. Administration of the hepatotoxin lipopolysaccharide/D-Galactosamine (LPS/GalN) resulted in marked liver injury in WKY, but not SD rats, with increased alanine aminotransferase (ALT), aspartate aminotransferase (AST) and glutamate dehydrogenase (GLDH) plasma levels, significant histopathological changes, increased hepatic pro-inflammatory cytokine expression and caspase-3 activity and expression and reduced Glutathione (GSH) activity. Furthermore, compared to SD controls, WKY rats display increased anandamide and 2-Arachidonoylglycerol levels concurrent with decreased expression of their metabolic enzymes and a decrease in cannabinoid (CB)1 receptor expression following LPS/GalN. CB1 antagonism with AM6545 or CB2 agonism with JWH133 did not alter LPS/GalN-induced liver injury in SD or WKY rats. These findings demonstrate exacerbation of acute liver injury induced by LPS/GalN in a stress-sensitive rat strain, with effects associated with alterations in the hepatic endocannabinoid system. Further studies are required to determine if the endocannabinoid system mediates or modulates the exacerbation of liver injury in this stress-sensitive rat strain.
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O'Sullivan G, Humphrey RM, Thornton AM, Kerr DM, McGuire BE, Caes L, Roche M. Maternal presence or absence alters nociceptive responding and cortical anandamide levels in juvenile female rats. Behav Brain Res 2020; 392:112712. [PMID: 32479851 DOI: 10.1016/j.bbr.2020.112712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 04/21/2020] [Accepted: 05/16/2020] [Indexed: 10/24/2022]
Abstract
The influence of parental support on child pain experiences is well recognised. Accordingly, animal studies have revealed both short- and long-term effects of early life stress on nociceptive responding and neural substrates such as endocannabinoids. The endocannabinoid system plays an important role in mediating and modulating stress, social interaction, and nociception. This study examined the effects of maternal support or acute isolation on nociceptive responding of female rats to a range of stimuli during the juvenile pre-adolescent period and accompanying changes in the endocannabinoid system. The data revealed that juvenile female Sprague Dawley rats (PND21-24) isolated from the dam for 1 h prior to nociceptive testing exhibited increased latency to withdraw in the hot plate test and increased mechanical withdrawal threshold in the Von Frey test, compared to rats tested in the presence of the dam. Furthermore, isolated rats exhibited reduced latency to respond in the acetone drop test and enhanced nociceptive responding in the formalin test when compared to dam-paired counterparts. Anandamide, but not 2-AG, levels were reduced in the prefrontal cortex of dam-paired, but not isolated, juvenile rats following nociceptive testing. There was no change in the expression of CB1, FAAH or MAGL; however, CB2 receptor expression was reduced in both dam-paired and isolated rats following nociceptive testing. Taken together the data demonstrate that brief social isolation or the presence of the dam modulates nociceptive responding of juvenile rat pups in a modality specific manner, and suggest a possible role for the endocannabinoid system in the prefrontal cortex in sociobehavioural pain responses during early life.
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Affiliation(s)
- Grace O'Sullivan
- Centre for Pain Research, National University of Ireland Galway, Ireland; School of Psychology, National University of Ireland Galway, Ireland
| | - Rachel M Humphrey
- Physiology, School of Medicine, National University of Ireland Galway, Ireland; Centre for Pain Research, National University of Ireland Galway, Ireland; Galway Neuroscience Centre, National University of Ireland Galway, Ireland
| | - Aoife M Thornton
- Physiology, School of Medicine, National University of Ireland Galway, Ireland; Galway Neuroscience Centre, National University of Ireland Galway, Ireland
| | - Daniel M Kerr
- Galway Neuroscience Centre, National University of Ireland Galway, Ireland; Pharmacology, School of Medicine, National University of Ireland Galway, Ireland
| | - Brian E McGuire
- Centre for Pain Research, National University of Ireland Galway, Ireland; School of Psychology, National University of Ireland Galway, Ireland
| | - Line Caes
- Psychology, Faculty of Natural Sciences, University of Stirling, Scotland, UK
| | - Michelle Roche
- Physiology, School of Medicine, National University of Ireland Galway, Ireland; Centre for Pain Research, National University of Ireland Galway, Ireland; Galway Neuroscience Centre, National University of Ireland Galway, Ireland.
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Ferizovic H, Spasojevic N, Stefanovic B, Jankovic M, Dronjak S. The fatty acid amide hydrolase inhibitor URB597 modulates splenic catecholamines in chronically stressed female and male rats. Int Immunopharmacol 2020; 85:106615. [PMID: 32447219 DOI: 10.1016/j.intimp.2020.106615] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 04/23/2020] [Accepted: 05/14/2020] [Indexed: 12/22/2022]
Abstract
The changes in sympathetic innervations in lymphoid organs could be a key factor in immune dysregulation. The endocannabinoid system has been shown to exhibit potent immunomodulatory effects that may differ between males and females, representing a potential therapeutic target for peripheral and central inflammatory disorders. Thus, in the present study, an examination was made of the effect of fatty acid amide hydrolase inhibitor URB597 treatment on splenic catecholamine content, synthesis, uptake and degradation in chronically unpredictably stressed (CUS) female and male rats. The results show that CUS increases anxiety-like behaviors and that URB597 had an anxiolytic effect on chronically stressed animals of both sexes. CUS induced the expression of plasma interleukin - 6 (IL-6), interleukin - 10 (IL-10) and IL-6 in the spleen, whereas the expression of IL-10 was reduced in the spleen of both sexes. URB597 treatment did not cause changes in IL-6 in plasma or the spleen, whereas it increased IL-10 in the spleen in CUS animals of both sexes. CUS caused a significant depletion of noradrenaline content in the spleen of female rats and a reduction in noradrenaline uptake in the spleen of female rats, while stressed males had a small but insignificant decrease of splenic noradrenaline levels and an enhanced uptake. The FAAH inhibitor URB597 enhances reduced noradrenaline content, affecting its uptake directly at the level of the spleen. It gives rise to the possibility that endocannabinoids exert a neurorestorative effect on the sympathetic nerve system and cell-mediated immune responses in the spleen of chronically stressed rats.
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Affiliation(s)
- Harisa Ferizovic
- Department of Molecular Biology and Endocrinology, "Vinča" Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Natasa Spasojevic
- Department of Molecular Biology and Endocrinology, "Vinča" Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Bojana Stefanovic
- Department of Molecular Biology and Endocrinology, "Vinča" Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Milica Jankovic
- Department of Molecular Biology and Endocrinology, "Vinča" Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Sladjana Dronjak
- Department of Molecular Biology and Endocrinology, "Vinča" Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia.
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12
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Hughes EM, Calcagno P, Clarke M, Sanchez C, Smith K, Kelly JP, Finn DP, Roche M. Prenatal exposure to valproic acid reduces social responses and alters mRNA levels of opioid receptor and pre-pro-peptide in discrete brain regions of adolescent and adult male rats. Brain Res 2020; 1732:146675. [PMID: 31978376 DOI: 10.1016/j.brainres.2020.146675] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 01/15/2020] [Accepted: 01/17/2020] [Indexed: 12/21/2022]
Abstract
Altered social behaviours are a hallmark of several psychiatric and developmental disorders. Clinical and preclinical data have demonstrated that prenatal exposure to valproic acid (VPA), an anti-epileptic and mood stabiliser, is associated with impaired social responses, and thus provides a useful model for the evaluation of neurobiological mechanisms underlying altered social behaviours. The opioid system is widely recognised to regulate and modulate social behaviours, however few studies have examined if the endogenous opioid system is altered in animal models of social impairment. The present study examined social behavioural responses of adolescent and adult male rats prenatally exposed to VPA, and the expression of mRNA encoding opioid receptors and pre-pro-peptides in discrete brain regions. Adolescent and adult rats prenatally exposed to VPA spent less time engaging in social behaviours in the direct social interaction test and exhibited reduced sociability and social novelty preference in the 3-chamber sociability test, compared to saline-treated counterparts. The VPA-exposed adolescent rats exhibited significantly reduced kappa opioid receptor (oprk1) and pre-pro-dynorphin (pdyn) mRNA expression in the cerebral cortex, and reduced oprk1 and nociceptin/orphanin FQ (oprl1) mRNA expression in the hypothalamus. Adult rats prenatally exposed to VPA exhibited decreased mRNA expression of oprk1 and pdyn in hypothalamus, reduced pro-opiomelanocortin(pomc) in the striatum and an increase in delta opioid receptor (oprd1) mRNA in the amygdaloid cortex, when compared to saline-treated counterparts. Mu opioid receptor (oprm1) mRNA expression did not differ between saline and VPA-exposed rats in any region examined. The data demonstrate that impaired social behaviours in adolescent and adult rats prenatally exposed to VPA is accompanied by altered mRNA expression of opioid receptors and pre-pro-peptides in a region specific manner. In particular, both adolescent and adult VPA-exposed rats exhibit reduced oprk1-pdyn mRNA expression in several brain regions, which are associated with deficits in social behavioural responding in the model.
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Affiliation(s)
- Edel M Hughes
- Physiology, School of Medicine, National University of Ireland, Galway, University Road, Galway, Ireland; Centre for Pain Research and Galway Neuroscience Centre, National University of Ireland, Galway, Ireland
| | - Patricia Calcagno
- Physiology, School of Medicine, National University of Ireland, Galway, University Road, Galway, Ireland; Pharmacology and Therapeutics, School of Medicine, National University of Ireland, Galway, University Road, Galway, Ireland
| | - Morgane Clarke
- Physiology, School of Medicine, National University of Ireland, Galway, University Road, Galway, Ireland; Pharmacology and Therapeutics, School of Medicine, National University of Ireland, Galway, University Road, Galway, Ireland
| | | | | | - John P Kelly
- Pharmacology and Therapeutics, School of Medicine, National University of Ireland, Galway, University Road, Galway, Ireland; Centre for Pain Research and Galway Neuroscience Centre, National University of Ireland, Galway, Ireland
| | - David P Finn
- Pharmacology and Therapeutics, School of Medicine, National University of Ireland, Galway, University Road, Galway, Ireland; Centre for Pain Research and Galway Neuroscience Centre, National University of Ireland, Galway, Ireland
| | - Michelle Roche
- Physiology, School of Medicine, National University of Ireland, Galway, University Road, Galway, Ireland; Centre for Pain Research and Galway Neuroscience Centre, National University of Ireland, Galway, Ireland.
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13
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Flannery LE, Kerr DM, Finn DP, Roche M. FAAH inhibition attenuates TLR3-mediated hyperthermia, nociceptive- and anxiety-like behaviour in female rats. Behav Brain Res 2018; 353:11-20. [PMID: 29953903 DOI: 10.1016/j.bbr.2018.06.030] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 05/21/2018] [Accepted: 06/25/2018] [Indexed: 01/09/2023]
Abstract
Aberrant activation of toll-like receptor (TLR)s results in persistent and prolonged neuroinflammation and has been implicated in the pathogenesis and exacerbation of psychiatric and neurodegenerative disorders. TLR3 coordinates the innate immune response to viral infection and recent data have demonstrated that inhibiting fatty acid amide hydrolase (FAAH), the enzyme that primarily metabolizes anandamide, modulates TLR3-mediated neuroinflammation. However, the physiological and behavioural consequences of such modulation are unknown. The present study examined the effect of URB597, a selective FAAH inhibitor, on neuroinflammation, physiological and behavioural alterations following administration of the TLR3 agonist and viral mimetic poly I:C to female rats. URB597 attenuated TLR3-mediated fever, mechanical and cold allodynia, and anxiety-like behaviour in the elevated plus maze and open field arena. There was no effect of URB597 on TLR3-mediated decreases in body weight and no effect in the sucrose preference or forced swim tests. URB597 attenuated the TLR3-mediated increase in the expression of CD11b and CD68, markers of microglia/macrophage activation. In summary, these data demonstrate that enhancing FAAH substrate levels suppresses TLR3-mediated microglia/macrophage activation and associated changes in fever, nociceptive responding and anxiety-related behaviour. These data provide further support for FAAH as a novel therapeutic target for neuroinflammatory disorders.
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Affiliation(s)
- Lisa E Flannery
- Physiology, School of Medicine, National University of Ireland Galway, Ireland; NCBES Centre for Pain Research and Galway Neuroscience Centre, National University of Ireland Galway, Ireland
| | - Daniel M Kerr
- Physiology, School of Medicine, National University of Ireland Galway, Ireland; Pharmacology and Therapeutics, School of Medicine, National University of Ireland Galway, Ireland; NCBES Centre for Pain Research and Galway Neuroscience Centre, National University of Ireland Galway, Ireland
| | - David P Finn
- Pharmacology and Therapeutics, School of Medicine, National University of Ireland Galway, Ireland; NCBES Centre for Pain Research and Galway Neuroscience Centre, National University of Ireland Galway, Ireland
| | - Michelle Roche
- Physiology, School of Medicine, National University of Ireland Galway, Ireland; NCBES Centre for Pain Research and Galway Neuroscience Centre, National University of Ireland Galway, Ireland.
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