1
|
Grether U, Foxton RH, Gruener S, Korn C, Kimbara A, Osterwald A, Zirwes E, Uhles S, Thoele J, Colé N, Rogers-Evans M, Röver S, Nettekoven M, Martin RE, Adam JM, Fingerle J, Bissantz C, Guba W, Alker A, Szczesniak AM, Porter RF, Toguri TJ, Revelant F, Poirier A, Perret C, Winther L, Caruso A, Fezza F, Maccarrone M, Kelly MEM, Fauser S, Ullmer C. RG7774 (Vicasinabin), an orally bioavailable cannabinoid receptor 2 (CB2R) agonist, decreases retinal vascular permeability, leukocyte adhesion, and ocular inflammation in animal models. Front Pharmacol 2024; 15:1426446. [PMID: 39070793 PMCID: PMC11272598 DOI: 10.3389/fphar.2024.1426446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Accepted: 06/19/2024] [Indexed: 07/30/2024] Open
Abstract
Introduction Preclinical studies suggest that cannabinoid receptor type 2 (CB2R) activation has a therapeutic effect in animal models on chronic inflammation and vascular permeability, which are key pathological features of diabetic retinopathy (DR). A novel CB2R agonist, triazolopyrimidine RG7774, was generated through lead optimization of a high-throughput screening hit. The aim of this study was to characterize the pharmacology, absorption, distribution, metabolism, elimination, and toxicity (ADMET) profile of RG7774, and to explore its potential for managing the key pathological features associated with retinal disease in rodents. Methods The in vitro pharmacology of RG7774 was investigated for CB2R binding and receptor activation using recombinant human and mouse CB2R expression in Chinese hamster ovary cells, and endogenous CB2R expression in human Jurkat cells, and rat and mouse spleen cells. The ADMET profile was evaluated and the effects of RG7774 on retinal permeability, leukocyte adhesion, and choroidal neovascularization (CNV) were investigated in rodent models of retinal disease. Pharmacokinetic (PK) parameters and the exposure-response relationship were characterized in healthy animals and in animals with laser-induced CNV. Results RG7774 was found to be a potent (EC50: 2.8 nM and Ki: 51.3 nM), selective, and full CB2R agonist with no signs of cannabinoid receptor type 1 (CB1R) binding or activation. The ligand showed a favorable ADMET profile and exhibited systemic and ocular exposure after oral delivery. Functional potency in vitro translated from recombinant to endogenous expression systems. In vivo, orally administered RG7774 reduced retinal permeability and leukocyte adhesion in rodents with lipopolysaccharide (LPS)-induced uveitis and streptozotocin (STZ)-induced DR, and reduced lesion areas in rats with laser-induced CNV with an ED50 of 0.32 mg/kg. Anatomically, RG7774 reduced the migration of retinal microglia to retinal lesions. Discussion RG7774 is a novel, highly selective, and orally bioavailable CB2R agonist, with an acceptable systemic and ocular PK profile, and beneficial effects on retinal vascular permeability, leukocyte adhesion, and ocular inflammation in rodent animal models. Results support the development of RG7774 as a potential treatment for retinal diseases with similar pathophysiologies as addressed by the animal models.
Collapse
Affiliation(s)
- Uwe Grether
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Richard H. Foxton
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Sabine Gruener
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Claudia Korn
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Atsushi Kimbara
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Anja Osterwald
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Elisabeth Zirwes
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Sabine Uhles
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Janina Thoele
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Nadine Colé
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Mark Rogers-Evans
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Stephan Röver
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Matthias Nettekoven
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Rainer E. Martin
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Jean-Michel Adam
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Jürgen Fingerle
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Caterina Bissantz
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Wolfgang Guba
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - André Alker
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Anna M. Szczesniak
- Departments of Pharmacology, Anesthesia, Ophthalmology and Visual Sciences, Dalhousie University, Halifax, NS, Canada
| | - Ross F. Porter
- Departments of Pharmacology, Anesthesia, Ophthalmology and Visual Sciences, Dalhousie University, Halifax, NS, Canada
| | - Tom J. Toguri
- Departments of Pharmacology, Anesthesia, Ophthalmology and Visual Sciences, Dalhousie University, Halifax, NS, Canada
| | - Franco Revelant
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Agnès Poirier
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Camille Perret
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Lotte Winther
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Antonello Caruso
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Filomena Fezza
- Department of Experimental Medicine, University of Rome Tor Vergata, Rome, Italy
| | - Mauro Maccarrone
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, L’Aquila, Italy
- European Center for Brain Research (CERC), Santa Lucia Foundation IRCCS, Rome, Italy
| | - Melanie E. M. Kelly
- Departments of Pharmacology, Anesthesia, Ophthalmology and Visual Sciences, Dalhousie University, Halifax, NS, Canada
| | - Sascha Fauser
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Christoph Ullmer
- F. Hoffmann-La Roche Ltd, Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| |
Collapse
|
2
|
Estay SF, Morales-Moraga C, Vielma AH, Palacios-Muñoz A, Chiu CQ, Chávez AE. Non-canonical type 1 cannabinoid receptor signaling regulates night visual processing in the inner rat retina. iScience 2024; 27:109920. [PMID: 38799553 PMCID: PMC11126983 DOI: 10.1016/j.isci.2024.109920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 04/18/2024] [Accepted: 05/03/2024] [Indexed: 05/29/2024] Open
Abstract
Type 1 cannabinoid receptors (CB1Rs) are expressed in major retinal neurons within the rod-pathway suggesting a role in regulating night visual processing, but the underlying mechanisms remain poorly understood. Using acute rat retinal slices, we show that CB1R activation reduces glutamate release from rod bipolar cell (RBC) axon terminals onto AII and A17 amacrine cells through a pathway that requires exchange proteins directly activated by cAMP (EPAC1/2) signaling. Consequently, CB1R activation abrogates reciprocal GABAergic feedback inhibition from A17 amacrine cells. Moreover, the activation of CB1Rs in vivo enhances and prolongs the time course of the dim-light rod-driven visual responses, an effect that was eliminated when both GABAA and GABAC receptors were blocked. Altogether, our findings underscore a non-canonical mechanism by which cannabinoid signaling regulates RBC dyad synapses in the inner retina to regulate dim-light visual responses to fine-tune night vision.
Collapse
Affiliation(s)
- Sebastián F. Estay
- Programa de Doctorado en Ciencias, Mención Neurociencia, Valparaíso 2340000, Chile
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Instituto de Neurociencias, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2340000, Chile
| | - Camila Morales-Moraga
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Instituto de Neurociencias, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2340000, Chile
| | - Alex H. Vielma
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Instituto de Neurociencias, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2340000, Chile
| | - Angelina Palacios-Muñoz
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Instituto de Neurociencias, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2340000, Chile
| | - Chiayu Q. Chiu
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Instituto de Neurociencias, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2340000, Chile
| | - Andrés E. Chávez
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Instituto de Neurociencias, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2340000, Chile
| |
Collapse
|
3
|
Papadogkonaki S, Spyridakos D, Lapokonstantaki E, Chaniotakis N, Makriyannis A, Malamas MS, Thermos K. Investigating the Effects of Exogenous and Endogenous 2-Arachidonoylglycerol on Retinal CB1 Cannabinoid Receptors and Reactive Microglia in Naive and Diseased Retina. Int J Mol Sci 2023; 24:15689. [PMID: 37958673 PMCID: PMC10650178 DOI: 10.3390/ijms242115689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 10/22/2023] [Accepted: 10/26/2023] [Indexed: 11/15/2023] Open
Abstract
The endocannabinoid system (ECS) is a new target for the development of retinal disease therapeutics, whose pathophysiology involves neurodegeneration and neuroinflammation. The endocannabinoid 2-arachidonoylglycerol (2-AG) affects neurons and microglia by activating CB1/CB2 cannabinoid receptors (Rs). The aim of this study was to investigate the effects of 2-AG on the CB1R expression/downregulation and retinal neurons/reactive microglia, when administered repeatedly (4 d), in three different paradigms. These involved the 2-AG exogenous administration (a) intraperitoneally (i.p.) and (b) topically and (c) by enhancing the 2-AG endogenous levels via the inhibition (AM11920, i.p.) of its metabolic enzymes (MAGL/ABHD6). Sprague Dawley rats were treated as mentioned above in the presence or absence of CB1/CB2R antagonists and the excitatory amino acid, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). Immunohistochemistry, Western blot and a 2-AG level analyses were performed. The 2-AG repeated treatment (i.p.) induced the CB1R downregulation, abolishing its neuroprotective actions. However, 2-AG attenuated the AMPA-induced activation of microglia via the CB2R, as concurred by the AM630 antagonist effect. Topically administered 2-AG was efficacious as a neuroprotectant/antiapoptotic and anti-inflammatory agent. AM11920 increased the 2-AG levels providing neuroprotection against excitotoxicity and reduced microglial activation without affecting the CB1R expression. Our findings show that 2-AG, in the three paradigms studied, displays differential pharmacological profiles in terms of the downregulation of the CB1R and neuroprotection. All treatments, however, attenuated the activation of microglia via the CB2R activation, supporting the anti-inflammatory role of 2-AG in the retina.
Collapse
Affiliation(s)
- Sofia Papadogkonaki
- Department of Pharmacology, School of Medicine, University of Crete, Heraklion, 71003 Crete, Greece; (S.P.); (D.S.)
| | - Dimitris Spyridakos
- Department of Pharmacology, School of Medicine, University of Crete, Heraklion, 71003 Crete, Greece; (S.P.); (D.S.)
| | | | - Nikos Chaniotakis
- Department of Chemistry, University of Crete, Heraklion, 71003 Crete, Greece; (E.L.); (N.C.)
| | - Alexandros Makriyannis
- Center for Drug Discovery and Departments of Chemistry and Chemical Biology and Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA; (A.M.); (M.S.M.)
| | - Michael S. Malamas
- Center for Drug Discovery and Departments of Chemistry and Chemical Biology and Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA; (A.M.); (M.S.M.)
| | - Kyriaki Thermos
- Department of Pharmacology, School of Medicine, University of Crete, Heraklion, 71003 Crete, Greece; (S.P.); (D.S.)
| |
Collapse
|
4
|
Polyunsaturated Lipids in the Light-Exposed and Prooxidant Retinal Environment. Antioxidants (Basel) 2023; 12:antiox12030617. [PMID: 36978865 PMCID: PMC10044808 DOI: 10.3390/antiox12030617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/26/2023] [Accepted: 02/28/2023] [Indexed: 03/06/2023] Open
Abstract
The retina is an oxidative stress-prone tissue due to high content of polyunsaturated lipids, exposure to visible light stimuli in the 400–480 nm range, and high oxygen availability provided by choroidal capillaries to support oxidative metabolism. Indeed, lipids’ peroxidation and their conversion into reactive species promoting inflammation have been reported and connected to retinal degenerations. Here, we review recent evidence showing how retinal polyunsaturated lipids, in addition to oxidative stress and damage, may counteract the inflammatory response triggered by blue light-activated carotenoid derivatives, enabling long-term retina operation despite its prooxidant environment. These two aspects of retinal polyunsaturated lipids require tight control over their synthesis to avoid overcoming their protective actions by an increase in lipid peroxidation due to oxidative stress. We review emerging evidence on different transcriptional control mechanisms operating in retinal cells to modulate polyunsaturated lipid synthesis over the life span, from the immature to the ageing retina. Finally, we discuss the antioxidant role of food nutrients such as xanthophylls and carotenoids that have been shown to empower retinal cells’ antioxidant responses and counteract the adverse impact of prooxidant stimuli on sight.
Collapse
|
5
|
Grabon W, Bodennec J, Rheims S, Belmeguenai A, Bezin L. Update on the controversial identity of cells expressing cnr2 gene in the nervous system. CNS Neurosci Ther 2023; 29:760-770. [PMID: 36604187 PMCID: PMC9928557 DOI: 10.1111/cns.13977] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 07/29/2022] [Accepted: 08/25/2022] [Indexed: 01/07/2023] Open
Abstract
The function of cannabinoid receptor type 2 (CB2R), mainly expressed by leukocytes, has long been limited to its peripheral immunomodulatory role. However, the use of CB2R-specific ligands and the availability of CB2R-Knock Out mice revealed that it could play a functional role in the CNS not only under physiological but also under pathological conditions. A direct effect on the nervous system emerged when CB2R mRNA was detected in neural tissues. However, accurate mapping of CB2R protein expression in the nervous system is still lacking, partly because of the lack of specificity of antibodies available. This review examines the regions and cells of the nervous system where CB2R protein is most likely present by cross-referencing mRNA and protein data published to date. Of the many antibodies developed to target CB2R, only a few have partially passed specificity tests and detected CB2R in the CNS. Efforts must be continued to support the development of more specific and better validated antibodies in each of the species in which CB2R protein is sought or needs to be quantified.
Collapse
Affiliation(s)
- Wanda Grabon
- Lyon Neuroscience Research CenterTIGER TeamBronFrance,Lyon 1 UniversityCNRS UMR 5292, Inserm U1028VilleurbanneFrance,Epilepsy Institute IDEEBronFrance
| | - Jacques Bodennec
- Lyon Neuroscience Research CenterTIGER TeamBronFrance,Lyon 1 UniversityCNRS UMR 5292, Inserm U1028VilleurbanneFrance,Epilepsy Institute IDEEBronFrance
| | - Sylvain Rheims
- Lyon Neuroscience Research CenterTIGER TeamBronFrance,Lyon 1 UniversityCNRS UMR 5292, Inserm U1028VilleurbanneFrance,Epilepsy Institute IDEEBronFrance
| | - Amor Belmeguenai
- Lyon Neuroscience Research CenterTIGER TeamBronFrance,Lyon 1 UniversityCNRS UMR 5292, Inserm U1028VilleurbanneFrance,Epilepsy Institute IDEEBronFrance
| | - Laurent Bezin
- Lyon Neuroscience Research CenterTIGER TeamBronFrance,Lyon 1 UniversityCNRS UMR 5292, Inserm U1028VilleurbanneFrance,Epilepsy Institute IDEEBronFrance
| |
Collapse
|
6
|
Spyridakos D, Mastrodimou N, Vemuri K, Ho TC, Nikas SP, Makriyannis A, Thermos K. Blockade of CB1 or Activation of CB2 Cannabinoid Receptors Is Differentially Efficacious in the Treatment of the Early Pathological Events in Streptozotocin-Induced Diabetic Rats. Int J Mol Sci 2022; 24:240. [PMID: 36613692 PMCID: PMC9820336 DOI: 10.3390/ijms24010240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 12/19/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022] Open
Abstract
Oxidative stress, neurodegeneration, neuroinflammation, and vascular leakage are believed to play a key role in the early stage of diabetic retinopathy (ESDR). The aim of this study was to investigate the blockade of cannabinoid receptor 1 (CB1R) and activation of cannabinoid receptor 2 (CB2R) as putative therapeutics for the treatment of the early toxic events in DR. Diabetic rats [streptozotocin (STZ)-induced] were treated topically (20 μL, 10 mg/mL), once daily for fourteen days (early stage DR model), with SR141716 (CB1R antagonist), AM1710 (CB2R agonist), and the dual treatment SR141716/AM1710. Immunohistochemical-histological, ELISA, and Evans-Blue analyses were performed to assess the neuroprotective and vasculoprotective properties of the pharmacological treatments on diabetes-induced retinal toxicity. Activation of CB2R or blockade of CB1R, as well as the dual treatment, attenuated the nitrative stress induced by diabetes. Both single treatments protected neural elements (e.g., RGC axons) and reduced vascular leakage. AM1710 alone reversed all toxic insults. These findings provide new knowledge regarding the differential efficacies of the cannabinoids, when administered topically, in the treatment of ESDR. Cannabinoid neuroprotection of the diabetic retina in ESDR may prove therapeutic in delaying the development of the advanced stage of the disease.
Collapse
Affiliation(s)
- Dimitris Spyridakos
- Department of Pharmacology, School of Medicine, University of Crete, 71003 Heraklion, Greece
| | - Niki Mastrodimou
- Department of Pharmacology, School of Medicine, University of Crete, 71003 Heraklion, Greece
| | - Kiran Vemuri
- Center for Drug Discovery, Departments of Chemistry and Chemical Biology and Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
| | - Thanh C. Ho
- Center for Drug Discovery, Departments of Chemistry and Chemical Biology and Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
| | - Spyros P. Nikas
- Center for Drug Discovery, Departments of Chemistry and Chemical Biology and Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
| | - Alexandros Makriyannis
- Center for Drug Discovery, Departments of Chemistry and Chemical Biology and Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
| | - Kyriaki Thermos
- Department of Pharmacology, School of Medicine, University of Crete, 71003 Heraklion, Greece
| |
Collapse
|
7
|
CB 1R, CB 2R and TRPV1 expression and modulation in in vivo, animal glaucoma models: A systematic review. Biomed Pharmacother 2022; 150:112981. [PMID: 35468582 DOI: 10.1016/j.biopha.2022.112981] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 04/06/2022] [Accepted: 04/14/2022] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND The endocannabinoid system (ECS) is a complex biological regulatory system. Its expression and functionality have been widely investigated in ocular tissues. Recent data have reported its modulation to be valid in determining an ocular hypotensive and a neuroprotective effect in preclinical animal models of glaucoma. AIM This study aimed to explore the available literature on cannabinoid receptor 1 (CB1R), cannabinoid receptor 2 (CB2R), and transient receptor potential vanilloid 1 (TRPV1) expression in the trabecular meshwork (TM), ciliary body (CB), and retina as well as their ocular hypotensive and neuroprotective effects in preclinical, in vivo, animal glaucoma models. MATERIALS AND METHODS The study adhered to both PRISMA and SYRCLE guidelines. Sixty-nine full-length articles were included in the final analysis. RESULTS Preclinical studies indicated a widespread distribution of CB1R, CB2R, and TRPV1 in the TM, CB, and retina, although receptor-, age-, and species-dependent differences were observed. CB1R and CB2R modulation have been shown to exert ocular hypotensive effects in preclinical models via the regulation of inflow and outflow pathways. Retinal cell neuroprotection has been achieved in several experimental models, mediated by agonists and antagonists of CB1R, CB2R, and TRPV1. DISCUSSION Despite the growing body of preclinical data regarding the expression and modulation of ECS in ocular tissues, the mechanisms responsible for the hypotensive and neuroprotective efficacy exerted by this system remain largely elusive. Research on this topic is advocated to further substantiate the hypothesis that the ECS is a new potential therapeutic target in the context of glaucoma.
Collapse
|
8
|
Neuroprotection of Retinal Ganglion Cells In Vivo Using the Activation of the Endogenous Cannabinoid Signaling System in Mammalian Eyes. Neuronal Signal 2022; 6:NS20210038. [PMID: 35233292 PMCID: PMC8850705 DOI: 10.1042/ns20210038] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 01/13/2022] [Accepted: 01/18/2022] [Indexed: 12/02/2022] Open
Abstract
Cannabinoid and glutamatergic signaling systems in the human retina coexist and greatly influence one another. Under glaucomatous conditions, excess levels of glutamate accrete in the retinal ganglion cell (RGC) layer. The present study tests the putative neuroprotective effect mediated by cannabinoids at the CB1 and CB2 receptors. In the first experiment, mice were given intravitreal injections of 160 nmol N-methyl-d-aspartic acid (NMDA) in one eye and saline in the paired eye. In the second experiment, both eyes were given NMDA, while one of the two was additionally given the cannabinoid agonist WIN 55,212-2. Ten days later, animals were perfused and the retinae were dissected as wholemounts and stained with Cresyl Violet. Quantitative analysis revealed that 70% of the neurons in the retinal ganglion cell (RGC) layer exposed to NMDA underwent cell death. The addition of the cannabinoid CB1/CB2 agonist doubled the number of neurons surviving the NMDA treatment. These data provide evidence that cannabinoids, either exogenous or endogenous, may be harnessed to provide protection from neurodegenerative diseases, including glaucoma, and from glutamate-induced, and potentially other forms of neurotoxicity, under chronic or acute conditions.
Collapse
|
9
|
The Inhibition of the Degrading Enzyme Fatty Acid Amide Hydrolase Alters the Activity of the Cone System in the Vervet Monkey Retina. Brain Sci 2021; 11:brainsci11111418. [PMID: 34827417 PMCID: PMC8615683 DOI: 10.3390/brainsci11111418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 10/20/2021] [Accepted: 10/25/2021] [Indexed: 11/17/2022] Open
Abstract
Recent studies using full-field electroretinography (ffERG) that triggers a non-specific mass response generated by several retinal sources have attributed an important role for cannabinoid receptors in mediating vision in primates. Specific cone-mediated responses evoked through the photopic flicker ERG appear to be a better way to validate the assumption that endogenous cannabinoids modulate the cone pathway, since FAAH is mainly expressed in the vervet monkey cone photoreceptors. The aim of this study is two-fold: (1) to use the photopic flicker ERG to target the cone pathway specifically, and (2) use URB597 as a selective inhibitor of the endocannabinoid degrading enzyme Fatty Acid Amide Hydrolase (FAAH) to enhance the levels of fatty acid amides, particularly anandamide. We recorded ERGs under four different flicker frequencies (15, 20, 25, and 30 Hz) in light-adapted conditions after intravitreal injections of URB597. Our results show that intravitreal injections of URB597, compared to the vehicle DMSO, increased significantly ffERG amplitudes at 30 Hz, a frequency that solely recruits cone activity. However, at 15 Hz, a frequency that activates both rods and cones, no significant difference was found in the ERG response amplitude. Additionally, we found no differences in implicit times after URB597 injections compared to DMSO vehicle. These results support the role of molecules degraded by FAAH in cone-mediated vision in non-human primates.
Collapse
|
10
|
Heinbockel T, Straiker A. Cannabinoids Regulate Sensory Processing in Early Olfactory and Visual Neural Circuits. Front Neural Circuits 2021; 15:662349. [PMID: 34305536 PMCID: PMC8294086 DOI: 10.3389/fncir.2021.662349] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 06/11/2021] [Indexed: 12/25/2022] Open
Abstract
Our sensory systems such as the olfactory and visual systems are the target of neuromodulatory regulation. This neuromodulation starts at the level of sensory receptors and extends into cortical processing. A relatively new group of neuromodulators includes cannabinoids. These form a group of chemical substances that are found in the cannabis plant. Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) are the main cannabinoids. THC acts in the brain and nervous system like the chemical substances that our body produces, the endogenous cannabinoids or endocannabinoids, also nicknamed the brain's own cannabis. While the function of the endocannabinoid system is understood fairly well in limbic structures such as the hippocampus and the amygdala, this signaling system is less well understood in the olfactory pathway and the visual system. Here, we describe and compare endocannabinoids as signaling molecules in the early processing centers of the olfactory and visual system, the olfactory bulb, and the retina, and the relevance of the endocannabinoid system for synaptic plasticity.
Collapse
Affiliation(s)
- Thomas Heinbockel
- Department of Anatomy, Howard University College of Medicine, Washington, DC, United States
| | - Alex Straiker
- The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States
| |
Collapse
|
11
|
Duffy SS, Hayes JP, Fiore NT, Moalem-Taylor G. The cannabinoid system and microglia in health and disease. Neuropharmacology 2021; 190:108555. [PMID: 33845074 DOI: 10.1016/j.neuropharm.2021.108555] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 03/29/2021] [Accepted: 03/30/2021] [Indexed: 12/13/2022]
Abstract
Recent years have yielded significant advances in our understanding of microglia, the immune cells of the central nervous system (CNS). Microglia are key players in CNS development, immune surveillance, and the maintenance of proper neuronal function throughout life. In the healthy brain, homeostatic microglia have a unique molecular signature. In neurological diseases, microglia become activated and adopt distinct transcriptomic signatures, including disease-associated microglia (DAM) implicated in neurodegenerative disorders. Homeostatic microglia synthesise the endogenous cannabinoids 2-arachidonoylglycerol and anandamide and express the cannabinoid receptors CB1 and CB2 at constitutively low levels. Upon activation, microglia significantly increase their synthesis of endocannabinoids and upregulate their expression of CB2 receptors, which promote a protective microglial phenotype by enhancing their production of neuroprotective factors and reducing their production of pro-inflammatory factors. Here, we summarise the effects of the microglial cannabinoid system in the CNS demyelinating disease multiple sclerosis, the neurodegenerative diseases Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis, chronic inflammatory and neuropathic pain, and psychiatric disorders including depression, anxiety and schizophrenia. We discuss the therapeutic potential of cannabinoids in regulating microglial activity and highlight the need to further investigate their specific microglia-dependent immunomodulatory effects.
Collapse
Affiliation(s)
- Samuel S Duffy
- Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, UNSW Sydney, NSW, 2052, Australia
| | - Jessica P Hayes
- Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, UNSW Sydney, NSW, 2052, Australia
| | - Nathan T Fiore
- Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, UNSW Sydney, NSW, 2052, Australia
| | - Gila Moalem-Taylor
- Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, UNSW Sydney, NSW, 2052, Australia.
| |
Collapse
|
12
|
Kulu M, Özarslan Y, Ozsoy F, Karamustafalıoğlu O. Optical Coherence Tomography findings in patients with Multiple Substance Use Disorder. Cutan Ocul Toxicol 2021; 40:37-44. [PMID: 33555206 DOI: 10.1080/15569527.2021.1874007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
OBJECTIVE Optical Coherence Tomography (OCT) is a relatively new diagnosis method displaying biological tissue layers by with high-resolution sections. In the present study, the purpose was to examine the OCT findings of patients with Multiple Substance Use Disorder (MSUD) by comparing these findings with healthy controls. METHODS The study included 30 MSUD and 30 controls. Detailed biomicroscopic examinations were carried out for all participants, and intraocular pressure, followed by OCT. The central macular thickness (CMT), mean macular thickness (MMT), mean macular volume (MMV), and retinal nerve fibre layer thickness (RNFL) were measured by using OCT. RESULTS It was determined that the MMT and CMT were thinned in both eyes compared to the healthy controls. The MMV was decreased in both eyes in patients with substance use disorders compared to healthy controls. The RNFL and total thickness were thickened in temporal and inferior parts in patients with MSUD in both eyes compared to healthy. In the superior quadrant, thickening was detected only in the left eye. CONCLUSIONS Based on our results obtained here, it was concluded that vision-related findings should be carefully questioned and evaluated when treatment is planned for patients with substance use.
Collapse
Affiliation(s)
- Müberra Kulu
- Clinic of Psychiatry, Tokat Mental Health and Diseases Hospital, Tokat, Turkey
| | - Yakup Özarslan
- Clinic of Ophthalmology, Tokat State Hospital, Tokat, Turkey
| | - Filiz Ozsoy
- Clinic of Psychiatry, Tokat State Hospital, Tokat, Turkey
| | | |
Collapse
|
13
|
Kokona D, Spyridakos D, Tzatzarakis M, Papadogkonaki S, Filidou E, Arvanitidis KI, Kolios G, Lamani M, Makriyannis A, Malamas MS, Thermos K. The endocannabinoid 2-arachidonoylglycerol and dual ABHD6/MAGL enzyme inhibitors display neuroprotective and anti-inflammatory actions in the in vivo retinal model of AMPA excitotoxicity. Neuropharmacology 2021; 185:108450. [PMID: 33450278 DOI: 10.1016/j.neuropharm.2021.108450] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 12/17/2020] [Accepted: 01/03/2021] [Indexed: 12/14/2022]
Abstract
The endocannabinoid system has been shown to be a putative therapeutic target for retinal disease. Here, we aimed to investigate the ability of the endocannabinoid 2-arachidonoylglycerol (2-AG) and novel inhibitors of its metabolic enzymes, α/β-hydrolase domain-containing 6 (ABHD6) and monoacylglycerol lipase (MAGL), a) to protect the retina against excitotoxicity and b) the mechanisms involved in the neuroprotection. Sprague-Dawley rats, wild type and Akt2-/- C57BL/6 mice were intravitreally administered with phosphate-buffered saline or (RS)-α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid hydrobromide (AMPA). 2-AG was intravitreally co-administered with AMPA in the absence and presence of AM251 or AM630 (cannabinoid 1 and 2 receptor antagonists, respectively) or Wortmannin [Phosphoinositide 3-Kinase (PI3K)/Akt inhibitor]. Inhibitors of ABHD6 and dual ABHD6/MAGL (AM12100 and AM11920, respectively) were co-administered with AMPA intravitreally in rats. Immunohistochemistry was performed using antibodies raised against retinal neuronal markers (bNOS), microglia (Iba1) and macroglia (GFAP). TUNEL assay and real-time PCR were also employed. The CB2 receptor was expressed in rat retina (approx. 62% of CB1 expression). 2-AG attenuated the AMPA-induced increase in TUNEL+ cells. 2-AG activation of both CB1 and CB2 receptors and the PI3K/Akt downstream signaling pathway, as substantiated by the use of Akt2-/- mice, afforded neuroprotection against AMPA excitotoxicity. AM12100 and AM11920 attenuated the AMPA-induced glia activation and produced a dose-dependent partial neuroprotection, with the dual inhibitor AM11920 being more efficacious. These results show that 2-AG has the pharmacological profile of a putative therapeutic for retinal diseases characterized by neurodegeneration and neuroinflammation, when administered exogenously or by the inhibition of its metabolic enzymes.
Collapse
Affiliation(s)
- Despina Kokona
- Department of Pharmacology, School of Medicine, University of Crete, Heraklion, Crete, 71003, Greece.
| | - Dimitris Spyridakos
- Department of Pharmacology, School of Medicine, University of Crete, Heraklion, Crete, 71003, Greece.
| | - Manolis Tzatzarakis
- Department of Toxicology, School of Medicine, University of Crete, Heraklion, Crete, 71003, Greece.
| | - Sofia Papadogkonaki
- Department of Pharmacology, School of Medicine, University of Crete, Heraklion, Crete, 71003, Greece.
| | - Eirini Filidou
- Laboratory of Pharmacology, School of Medicine, Democritus University of Thrace, Alexandroupolis, 68100, Greece.
| | - Konstantinos I Arvanitidis
- Laboratory of Pharmacology, School of Medicine, Democritus University of Thrace, Alexandroupolis, 68100, Greece.
| | - George Kolios
- Laboratory of Pharmacology, School of Medicine, Democritus University of Thrace, Alexandroupolis, 68100, Greece.
| | - Manjunath Lamani
- Center for Drug Discovery and Departments of Chemistry and Chemical Biology and Pharmaceutical Sciences, Northeastern University, Boston, MA, 02115, USA.
| | - Alexandros Makriyannis
- Center for Drug Discovery and Departments of Chemistry and Chemical Biology and Pharmaceutical Sciences, Northeastern University, Boston, MA, 02115, USA.
| | - Michael S Malamas
- Center for Drug Discovery and Departments of Chemistry and Chemical Biology and Pharmaceutical Sciences, Northeastern University, Boston, MA, 02115, USA.
| | - Kyriaki Thermos
- Department of Pharmacology, School of Medicine, University of Crete, Heraklion, Crete, 71003, Greece.
| |
Collapse
|
14
|
Liu QR, Canseco-Alba A, Liang Y, Ishiguro H, Onaivi ES. Low Basal CB2R in Dopamine Neurons and Microglia Influences Cannabinoid Tetrad Effects. Int J Mol Sci 2020; 21:E9763. [PMID: 33371336 PMCID: PMC7767340 DOI: 10.3390/ijms21249763] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 12/04/2020] [Accepted: 12/17/2020] [Indexed: 12/13/2022] Open
Abstract
There are two well-characterized cannabinoid receptors (CB1R and CB2R and other candidates): the central nervous system (CNS) enriched CB1R and peripheral tissue enriched CB2R with a wide dynamic range of expression levels in different cell types of human tissues. Hepatocytes and neurons express low baseline CB1R and CB2R, respectively, and their cell-type-specific functions are not well defined. Here we report inducible expression of CB1R in the liver by high-fat and high sugar diet and CB2R in cortical neurons by methamphetamine. While there is less controversy about hepatocyte CB1R, the presence of functional neuronal CB2R is still debated to date. We found that neuron CB2R basal expression was higher than that of hepatocyte CB1R by measuring mRNA levels of specific isoform CB2A in neurons isolated by fluorescence-activated cell sorting (FACS) and CB1A in hepatocytes isolated by collagenase perfusion of liver. For in vivo studies, we generated hepatocyte, dopaminergic neuron, and microglia-specific conditional knockout mice (Abl-Cnr1Δ, Dat-Cnr2Δ, and Cx3cr1-Cnr2Δ) of CB1R and CB2R by crossing Cnr1f/f and Cnr2f/f strains to Abl-Cre, Dat-Cre, and Cx3cr1-Cre deleter mouse strains, respectively. Our data reveals that neuron and microglia CB2Rs are involved in the "tetrad" effects of the mixed agonist WIN 55212-2, CB1R selective agonist arachidonyl-2'-chloroethylamide (ACEA), and CB2R selective agonist JWH133. Dat-Cnr2Δ and Cx3cr1-Cnr2Δ mice showed genotypic differences in hypomobility, hypothermia, analgesia, and catalepsy induced by the synthetic cannabinoids. Alcohol conditioned place preference was abolished in DAT-Cnr2Δ mice and remained intact in Cx3cr1-Cnr2Δ mice in comparison to WT mice. These Cre-loxP recombinant mouse lines provide unique approaches in cannabinoid research for dissecting the complex endocannabinoid system that is implicated in many chronic disorders.
Collapse
MESH Headings
- Animals
- Behavior, Animal/drug effects
- Cannabinoids/pharmacology
- Dopaminergic Neurons/drug effects
- Dopaminergic Neurons/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Microglia/drug effects
- Microglia/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptor, Cannabinoid, CB1/genetics
- Receptor, Cannabinoid, CB1/metabolism
- Receptor, Cannabinoid, CB1/physiology
- Receptor, Cannabinoid, CB2/genetics
- Receptor, Cannabinoid, CB2/metabolism
- Receptor, Cannabinoid, CB2/physiology
Collapse
Affiliation(s)
- Qing-Rong Liu
- Laboratory of Clinical Investigation, National Institute on Aging, Baltimore, MD 21224, USA
| | - Ana Canseco-Alba
- Department of Biology, William Paterson University, Wayne, NJ 07470, USA;
| | - Ying Liang
- College of Food Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, Hunan, China;
| | - Hiroki Ishiguro
- Department of Neuropsychiatry, Graduate School of Medical Science, University of Yamanashi, Chuo, Yamanashi 409-3898, Japan;
| | - Emmanuel S. Onaivi
- Department of Biology, William Paterson University, Wayne, NJ 07470, USA;
| |
Collapse
|
15
|
Spyridakos D, Papadogkonaki S, Dionysopoulou S, Mastrodimou N, Polioudaki H, Thermos K. Effect of acute and subchronic administration of (R)-WIN55,212-2 induced neuroprotection and anti inflammatory actions in rat retina: CB1 and CB2 receptor involvement. Neurochem Int 2020; 142:104907. [PMID: 33220388 DOI: 10.1016/j.neuint.2020.104907] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 10/30/2020] [Accepted: 11/15/2020] [Indexed: 01/09/2023]
Abstract
Cannabinoids have been shown to protect the retina from ischemic/excitotoxic insults. The aim of the present study was to investigate the neuroprotective and anti-inflammatory properties of the synthetic cannabinoid (R)-WIN55,212-2 (CB1/CB2 receptor agonist) when administered acutely or subchronically in control and AMPA treated retinas. Sprague-Dawley rats were intravitreally administered (acutely) with vehicle or AMPA, in the absence or presence of (R)-WIN55,212-2 (10-7-10-4M) alone or in combination with AM251 [CB1 receptor antagonist/inverse agonist,10-4M] and AM630 (CB2 receptor antagonist,10-4M). In addition, AMPA was co-administered with the racemic (R,S)-WIN55,212 (10-4Μ). (R)-WIN55,212-2 was also administered subchronically (25,100 μg/kg,i.p.,4d) in control and AMPA treated rats. Immunohistochemical studies were performed using antibodies against the CB1R, and retinal markers for retinal neurons (brain nitric oxide synthetase, bNOS) and microglia (ionized calcium binding adaptor molecule 1, Iba1). ELISA assay was employed to assess TNFα levels in AMPA treated retinas. Intravitreal administration of (R)-WIN55,212-2 reversed the AMPA induced loss of bNOS expressing amacrine cells, an effect that was blocked by both AM251 and AM630. (R,S)WIN55,212 had no effect. (R)-WIN55,212-2 also reduced a) the AMPA induced activation of microglia, by activating CB2 receptors that were shown to be colocalized with Iba1+ reactive microglial cells, and b) TNFα levels in retina. (R)-WIN55,212-2 administered subchronically led to the downregulation of CB1 receptors at the high dose of 100 μg/kg(i.p.), and to the attenuation of the WIN55,212-2 induced neuroprotection of amacrine cells. At the same dose, (R)-WIN55,212-2 did not attenuate the AMPA induced increase in the number of reactive microglia cells, suggesting CB2 receptor downregulation under subchronic conditions. This study provides new findings regarding the role of CB1 and CB2 receptor activation by the synthetic cannabinoid (R)-WIN55,212-2, administered acutely or sub-chronically, on neuron viability and microglia activation in healthy and diseased retina.
Collapse
MESH Headings
- Animals
- Anti-Inflammatory Agents/administration & dosage
- Benzoxazines/administration & dosage
- Dose-Response Relationship, Drug
- Drug Administration Schedule
- Female
- Male
- Morpholines/administration & dosage
- Naphthalenes/administration & dosage
- Neuroprotective Agents/administration & dosage
- Rats
- Rats, Sprague-Dawley
- Receptor, Cannabinoid, CB1/agonists
- Receptor, Cannabinoid, CB1/metabolism
- Receptor, Cannabinoid, CB2/agonists
- Receptor, Cannabinoid, CB2/metabolism
- Retina/drug effects
- Retina/metabolism
- alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid/toxicity
Collapse
Affiliation(s)
- Dimitris Spyridakos
- Department of Pharmacology, School of Medicine, University of Crete, Heraklion, Crete, 71003, Greece.
| | - Sofia Papadogkonaki
- Department of Pharmacology, School of Medicine, University of Crete, Heraklion, Crete, 71003, Greece.
| | - Stavroula Dionysopoulou
- Department of Pharmacology, School of Medicine, University of Crete, Heraklion, Crete, 71003, Greece.
| | - Niki Mastrodimou
- Department of Pharmacology, School of Medicine, University of Crete, Heraklion, Crete, 71003, Greece.
| | - Hara Polioudaki
- Department of Biochemistry, School of Medicine, University of Crete, Heraklion, Crete, 71003, Greece.
| | - Kyriaki Thermos
- Department of Pharmacology, School of Medicine, University of Crete, Heraklion, Crete, 71003, Greece.
| |
Collapse
|
16
|
Cannabinoids affect the mouse visual acuity via the cannabinoid receptor type 2. Sci Rep 2020; 10:15819. [PMID: 32978469 PMCID: PMC7519129 DOI: 10.1038/s41598-020-72553-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 09/02/2020] [Indexed: 12/18/2022] Open
Abstract
Recently, there have been increasing indications that the endocannabinoid (eCB) system is involved in vision. Multiple research teams studied the cannabinoid receptor type 2 (CB2R) expression and function in the mouse retina. Here, we examined the consequence of CB2R modulation on visual acuity using genetic and pharmacologic tools. We found that Cnr2 knockout mice show an enhanced visual acuity, CB2R activation decreased visual acuity while CB2R blockade with the inverse agonist AM630 increased it. The inhibition of 2-arachidonylglycerol (2-AG) synthesis and degradation also greatly increased and decreased visual acuity, respectively. No differences were seen when the cannabinoid receptor type 1 (CB1R) was deleted, blocked or activated implying that CB2R exclusively mediates cannabinoid modulation of the visual acuity. We also investigated the role of cannabinoids in retinal function using electroretinography (ERG). We found that modulating 2-AG levels affected many ERG components, such as the a-wave and oscillatory potentials (OPs), suggesting an impact on cones and amacrine cells. Taken together, these results reveal that CB2R modulates visual acuity and that eCBs such as 2-AG can modulate both visual acuity and retinal sensitivity. Finally, these findings establish that CB2R is present in visual areas and regulates vision-related functions.
Collapse
|
17
|
Miller S, Daily L, Dharla V, Gertsch J, Malamas MS, Ojima I, Kaczocha M, Ogasawara D, Straiker A. Endocannabinoid metabolism and transport as targets to regulate intraocular pressure. Exp Eye Res 2020; 201:108266. [PMID: 32979397 DOI: 10.1016/j.exer.2020.108266] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 08/17/2020] [Accepted: 09/21/2020] [Indexed: 02/06/2023]
Abstract
Cannabinoids are part of an endogenous signaling system found throughout the body, including the eye. Hepler and Frank showed in the early 1970s that plant cannabinoids can lower intraocular pressure (IOP), an effect since shown to occur via cannabinoid CB1 and GPR18 receptors. Endocannabinoids are synthesized and metabolized enzymatically. Enzymes implicated in endocannabinoids breakdown include monoacylglycerol lipase (MAGL) and fatty acid amide hydrolase (FAAH), but also ABHD12, NAAA, and COX-2. Inhibition of MAGL activity raises levels of the endocannabinoid 2-arachidonoyl glycerol and substantially lowers IOP. Blocking other cannabinoid metabolizing enzymes or cannabinoid transporters may similarly contribute to lowering IOP and so serve as therapeutic targets for treating glaucoma. We have tested blockers for several cannabinoid-metabolizing enzymes and transporters (FABP5 and membrane reuptake) for their ability to alter ocular pressure in a murine model of IOP. Of FAAH, ABHD12, NAAA, and COX2, only FAAH was seen to play a role in regulation of IOP. Only the FAAH blocker URB597 lowered IOP, but in a temporally, diurnally, and sex-specific manner. We also tested two blockers of cannabinoid transport (SBFI-26 and WOBE437), finding that each lowered IOP in a CB1-dependent manner. Though we see a modest, limited role for FAAH, our results suggest that MAGL is the primary cannabinoid-metabolizing enzyme in regulating ocular pressure, thus pointing towards a role of 2-arachidonoyl glycerol. Interestingly, inhibition of cannabinoid transport mechanisms independent of hydrolysis may prove to be an alternative strategy to lower ocular pressure.
Collapse
Affiliation(s)
- Sally Miller
- The Gill Center for Biomolecular Science, Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, 47405, USA
| | - Laura Daily
- The Gill Center for Biomolecular Science, Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, 47405, USA
| | - Vijai Dharla
- The Gill Center for Biomolecular Science, Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, 47405, USA
| | - Juerg Gertsch
- Institute of Biochemistry and Molecular Medicine, NCCR TransCure, University of Bern, Bühlstrasse 28, 3012, Bern, Switzerland
| | - Michael S Malamas
- Center for Drug Discovery and Departments of Chemistry and Chemical Biology and Pharmaceutical Sciences, Northeastern University, Boston, MA, 02115, USA
| | - Iwao Ojima
- Department of Chemistry, USA; Institute of Chemical Biology and Drug Discovery, USA
| | - Martin Kaczocha
- Institute of Chemical Biology and Drug Discovery, USA; Department of Anesthesiology, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Daisuke Ogasawara
- Department of Chemistry, Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Alex Straiker
- The Gill Center for Biomolecular Science, Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, 47405, USA.
| |
Collapse
|