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Lindner T, Schmidl D, Peschorn L, Pai V, Popa-Cherecheanu A, Chua J, Schmetterer L, Garhöfer G. Therapeutic Potential of Cannabinoids in Glaucoma. Pharmaceuticals (Basel) 2023; 16:1149. [PMID: 37631064 PMCID: PMC10460067 DOI: 10.3390/ph16081149] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 08/07/2023] [Accepted: 08/09/2023] [Indexed: 08/27/2023] Open
Abstract
Glaucoma is a leading cause of irreversible blindness worldwide. To date, intraocular pressure (IOP) is the only modifiable risk factor in glaucoma treatment, but even in treated patients, the disease can progress. Cannabinoids, which have been known to lower IOP since the 1970s, have been shown to have beneficial effects in glaucoma patients beyond their IOP-lowering properties. In addition to the classical cannabinoid receptors CB1 and CB2, knowledge of non-classical cannabinoid receptors and the endocannabinoid system has increased in recent years. In particular, the CB2 receptor has been shown to mediate anti-inflammatory, anti-apoptotic, and neuroprotective properties, which may represent a promising therapeutic target for neuroprotection in glaucoma patients. Due to their vasodilatory effects, cannabinoids improve blood flow to the optic nerve head, which may suggest a vasoprotective potential and counteract the altered blood flow observed in glaucoma patients. The aim of this review was to assess the available evidence on the effects and therapeutic potential of cannabinoids in glaucoma patients. The pharmacological mechanisms underlying the effects of cannabinoids on IOP, neuroprotection, and ocular hemodynamics have been discussed.
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Affiliation(s)
- Theresa Lindner
- Department of Clinical Pharmacology, Medical University Vienna, 1090 Vienna, Austria; (T.L.); (D.S.); (L.P.); (V.P.); (L.S.)
| | - Doreen Schmidl
- Department of Clinical Pharmacology, Medical University Vienna, 1090 Vienna, Austria; (T.L.); (D.S.); (L.P.); (V.P.); (L.S.)
| | - Laura Peschorn
- Department of Clinical Pharmacology, Medical University Vienna, 1090 Vienna, Austria; (T.L.); (D.S.); (L.P.); (V.P.); (L.S.)
| | - Viktoria Pai
- Department of Clinical Pharmacology, Medical University Vienna, 1090 Vienna, Austria; (T.L.); (D.S.); (L.P.); (V.P.); (L.S.)
| | - Alina Popa-Cherecheanu
- Department of Ophthalmology, Emergency University Hospital, 050098 Bucharest, Romania;
- Carol Davila University of Medicine and Pharmacy, 020021 Bucharest, Romania
| | - Jacqueline Chua
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore 169856, Singapore;
- Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Leopold Schmetterer
- Department of Clinical Pharmacology, Medical University Vienna, 1090 Vienna, Austria; (T.L.); (D.S.); (L.P.); (V.P.); (L.S.)
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore 169856, Singapore;
- Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore 169857, Singapore
- SERI-NTU Advanced Ocular Engineering (STANCE), Nanyang Technological University, Singapore 639798, Singapore
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore 637459, Singapore
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, 1090 Vienna, Austria
- Institute of Molecular and Clinical Ophthalmology, 4031 Basel, Switzerland
| | - Gerhard Garhöfer
- Department of Clinical Pharmacology, Medical University Vienna, 1090 Vienna, Austria; (T.L.); (D.S.); (L.P.); (V.P.); (L.S.)
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Vasincu A, Rusu RN, Ababei DC, Neamțu M, Arcan OD, Macadan I, Beșchea Chiriac S, Bild W, Bild V. Exploring the Therapeutic Potential of Cannabinoid Receptor Antagonists in Inflammation, Diabetes Mellitus, and Obesity. Biomedicines 2023; 11:1667. [PMID: 37371762 DOI: 10.3390/biomedicines11061667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 05/31/2023] [Accepted: 06/06/2023] [Indexed: 06/29/2023] Open
Abstract
Recently, research has greatly expanded the knowledge of the endocannabinoid system (ECS) and its involvement in several therapeutic applications. Cannabinoid receptors (CBRs) are present in nearly every mammalian tissue, performing a vital role in different physiological processes (neuronal development, immune modulation, energy homeostasis). The ECS has an essential role in metabolic control and lipid signaling, making it a potential target for managing conditions such as obesity and diabetes. Its malfunction is closely linked to these pathological conditions. Additionally, the immunomodulatory function of the ECS presents a promising avenue for developing new treatments for various types of acute and chronic inflammatory conditions. Preclinical investigations using peripherally restricted CBR antagonists that do not cross the BBB have shown promise for the treatment of obesity and metabolic diseases, highlighting the importance of continuing efforts to discover novel molecules with superior safety profiles. The purpose of this review is to examine the roles of CB1R and CB2Rs, as well as their antagonists, in relation to the above-mentioned disorders.
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Affiliation(s)
- Alexandru Vasincu
- Department of Pharmacodynamics and Clinical Pharmacy, "Grigore T. Popa" University of Medicine and Pharmacy, 16 Universitatii Street, 700115 Iasi, Romania
| | - Răzvan-Nicolae Rusu
- Department of Pharmacodynamics and Clinical Pharmacy, "Grigore T. Popa" University of Medicine and Pharmacy, 16 Universitatii Street, 700115 Iasi, Romania
| | - Daniela-Carmen Ababei
- Department of Pharmacodynamics and Clinical Pharmacy, "Grigore T. Popa" University of Medicine and Pharmacy, 16 Universitatii Street, 700115 Iasi, Romania
| | - Monica Neamțu
- Department of Pharmacodynamics and Clinical Pharmacy, "Grigore T. Popa" University of Medicine and Pharmacy, 16 Universitatii Street, 700115 Iasi, Romania
| | - Oana Dana Arcan
- Department of Pharmacodynamics and Clinical Pharmacy, "Grigore T. Popa" University of Medicine and Pharmacy, 16 Universitatii Street, 700115 Iasi, Romania
| | - Ioana Macadan
- Department of Pharmacodynamics and Clinical Pharmacy, "Grigore T. Popa" University of Medicine and Pharmacy, 16 Universitatii Street, 700115 Iasi, Romania
| | - Sorin Beșchea Chiriac
- Department of Toxicology, "Ion Ionescu de la Brad" University of Life Sciences, 8 M. Sadoveanu Alley, 700489 Iasi, Romania
| | - Walther Bild
- Department of Physiology, "Grigore T. Popa" University of Medicine and Pharmacy, 16 Universitatii Street, 700115 Iasi, Romania
- Center of Biomedical Research of the Romanian Academy, 700506 Iasi, Romania
| | - Veronica Bild
- Department of Pharmacodynamics and Clinical Pharmacy, "Grigore T. Popa" University of Medicine and Pharmacy, 16 Universitatii Street, 700115 Iasi, Romania
- Center of Biomedical Research of the Romanian Academy, 700506 Iasi, Romania
- Center for Advanced Research and Development in Experimental Medicine (CEMEX), "Grigore T. Popa" University of Medicine and Pharmacy, 16 Universitatii Street, 700115 Iasi, Romania
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Fujii Y, Arima M, Murakami Y, Sonoda KH. Rhodopsin-positive cell production by intravitreal injection of small molecule compounds in mouse models of retinal degeneration. PLoS One 2023; 18:e0282174. [PMID: 36821627 PMCID: PMC9949636 DOI: 10.1371/journal.pone.0282174] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Accepted: 02/08/2023] [Indexed: 02/24/2023] Open
Abstract
We aimed to verify whether the intravitreal injection of small molecule compounds alone can create photoreceptor cells in mouse models of retinal degeneration. Primary cultured mouse Müller cells were stimulated in vitro with combinations of candidate compounds and the rhodopsin expression was measured on day 7 using polymerase chain reaction and immunostaining. We used 6-week-old N-methyl-N-nitrosourea-treated and 4-week-old rd10 mice as representative in vivo models of retinal degeneration. The optimal combination of compounds selected via in vitro screening was injected into the vitreous and the changes in rhodopsin expression were investigated on day 7 using polymerase chain reaction and immunostaining. The origin of rhodopsin-positive cells was also analyzed via lineage tracing and the recovery of retinal function was assessed using electroretinography. The in vitro mRNA expression of rhodopsin in Müller cells increased 30-fold, and 25% of the Müller cells expressed rhodopsin protein 7 days after stimulation with a combination of 4 compounds: transforming growth factor-β inhibitor, bone morphogenetic protein inhibitor, glycogen synthase kinase 3 inhibitor, and γ-secretase inhibitor. The in vivo rhodopsin mRNA expression and the number of rhodopsin-positive cells in the outer retina were significantly increased on day 7 after the intravitreal injection of these 4 compounds in both N-methyl-N-nitrosourea-treated and rd10 mice. Lineage tracing in td-Tomato mice treated with N-methyl-N-nitrosourea suggested that the rhodopsin-positive cells originated from endogenous Müller cells, accompanied with the recovery of the rhodopsin-derived scotopic function. It was suggested that rhodopsin-positive cells generated by compound stimulation contributes to the recovery of retinal function impaired by degeneration.
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Affiliation(s)
- Yuya Fujii
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Mitsuru Arima
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan,Center for Clinical and Translational Research, Kyushu University Hospital, Fukuoka, Japan,* E-mail:
| | - Yusuke Murakami
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Koh-Hei Sonoda
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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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.
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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
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Soliño M, Larrayoz IM, López EM, Rey-Funes M, Bareiro M, Loidl CF, Girardi E, Caltana L, Brusco A, Martínez A, López-Costa JJ. CB1 Cannabinoid Receptor is a Target for Neuroprotection in Light Induced Retinal Degeneration. ADVANCES IN DRUG AND ALCOHOL RESEARCH 2022; 2:10734. [PMID: 38390616 PMCID: PMC10880786 DOI: 10.3389/adar.2022.10734] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 08/23/2022] [Indexed: 02/24/2024]
Abstract
In the last few years, an increasing interest in the neuroprotective effect of cannabinoids has taken place. The aim of the present work was to study the effects of modulating cannabinoid receptor 1 (CB1) in the context of light induced retinal degeneration (LIRD), using an animal model that resembles many characteristics of human age-related macular degeneration (AMD) and other degenerative diseases of the outer retina. Sprague Dawley rats (n = 28) were intravitreally injected in the right eye with either a CB1 agonist (ACEA), or an antagonist (AM251). Contralateral eyes were injected with respective vehicles as controls. Then, rats were subjected to continuous illumination (12,000 lux) for 24 h. Retinas from 28 animals were processed by GFAP-immunohistochemistry (IHC), TUNEL technique, Western blotting (WB), or qRT-PCR. ACEA-treated retinas showed a significantly lower number of apoptotic nuclei in the outer nuclear layer (ONL), lower levels of activated Caspase-3 by WB, and lower levels of glial reactivity by both GFAP-IHC and WB. qRT-PCR revealed that ACEA significantly decreased the expression of Bcl-2 and CYP1A1. Conversely, AM251-treated retinas showed a higher number of apoptotic nuclei in the ONL, higher levels of activated Caspase-3 by WB, and higher levels of glial reactivity as determined by GFAP-IHC and WB. AM251 increased the expression of Bcl-2, Bad, Bax, Aryl hydrocarbon Receptor (AhR), GFAP, and TNFα. In summary, the stimulation of the CB1 receptor, previous to the start of the pathogenic process, improved the survival of photoreceptors exposed to LIRD. The modulation of CB1 activity may be used as a neuroprotective strategy in retinal degeneration and deserves further studies.
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Affiliation(s)
- Manuel Soliño
- Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis" (IBCN), Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Ignacio M Larrayoz
- Biomarkers and Molecular Signaling Group, Center for Biomedical Research of La Rioja (CIBIR), Logroño, Spain
| | - Ester María López
- Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis" (IBCN), Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Manuel Rey-Funes
- Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis" (IBCN), Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Mariana Bareiro
- Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis" (IBCN), Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Cesar Fabián Loidl
- Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis" (IBCN), Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Elena Girardi
- Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis" (IBCN), Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Laura Caltana
- Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis" (IBCN), Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Alicia Brusco
- Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis" (IBCN), Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Alfredo Martínez
- Angiogenesis Study Group, Center for Biomedical Research of La Rioja (CIBIR), Logroño, Spain
| | - Juan José López-Costa
- Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis" (IBCN), Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
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6
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Niu Z, Shi Y, Li J, Qiao S, Du S, Chen L, Tian H, Wei L, Cao H, Wang J, Gao L. Protective effect of rapamycin in models of retinal degeneration. Exp Eye Res 2021; 210:108700. [PMID: 34245755 DOI: 10.1016/j.exer.2021.108700] [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] [Received: 02/08/2021] [Revised: 06/25/2021] [Accepted: 07/06/2021] [Indexed: 12/29/2022]
Abstract
Age-related macular degeneration (AMD) is a complex retinal disease with no viable treatment strategy. The causative mechanistic pathway for this disease is not yet clear. Therefore, it is highly warranted to screen effective drugs to treat AMD. Rapamycin are known to inhibit inflammation and has been widely used in the clinic as an immunosuppressant. This study aimed to investigate the protective effect of rapamycin on the AMD retinal degeneration model. The AMD models were established by injection of 35 mg/kg sodium iodate (NaIO3) into the tail vein. Then the treated mice intraperitoneally received rapamycin (2 mg/kg) once a day. The histomorphological analysis showed that rapamycin could inhibit retinal structure damage and apoptosis. Experiments revealed that rapamycin significantly attenuated inflammatory response and oxidative stress. Our experimental results demonstrated that rapamycin has protected the retinal against degeneration induced by NaIO3. The therapeutic effect was more significant after 7 days of treatment. Therefore, our study potentially provides a powerful experimental support for the treatment of AMD.
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Affiliation(s)
- Zhanyu Niu
- School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
| | - Yongpeng Shi
- School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
| | - Jiande Li
- School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
| | - Shufan Qiao
- Colloge of Life Sciences, Northwest Normal University, Lanzhou, 730000, China.
| | - Shaobo Du
- School of Stomatology of Lanzhou University, Lanzhou, 730000, China.
| | - Linchi Chen
- School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
| | - Huanbing Tian
- School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
| | - Li Wei
- School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
| | - Hanwen Cao
- School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
| | - Ji Wang
- School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
| | - Lan Gao
- School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
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Kasatkina LA, Rittchen S, Sturm EM. Neuroprotective and Immunomodulatory Action of the Endocannabinoid System under Neuroinflammation. Int J Mol Sci 2021; 22:ijms22115431. [PMID: 34063947 PMCID: PMC8196612 DOI: 10.3390/ijms22115431] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 05/17/2021] [Accepted: 05/18/2021] [Indexed: 12/17/2022] Open
Abstract
Endocannabinoids (eCBs) are lipid-based retrograde messengers with a relatively short half-life that are produced endogenously and, upon binding to the primary cannabinoid receptors CB1/2, mediate multiple mechanisms of intercellular communication within the body. Endocannabinoid signaling is implicated in brain development, memory formation, learning, mood, anxiety, depression, feeding behavior, analgesia, and drug addiction. It is now recognized that the endocannabinoid system mediates not only neuronal communications but also governs the crosstalk between neurons, glia, and immune cells, and thus represents an important player within the neuroimmune interface. Generation of primary endocannabinoids is accompanied by the production of their congeners, the N-acylethanolamines (NAEs), which together with N-acylneurotransmitters, lipoamino acids and primary fatty acid amides comprise expanded endocannabinoid/endovanilloid signaling systems. Most of these compounds do not bind CB1/2, but signal via several other pathways involving the transient receptor potential cation channel subfamily V member 1 (TRPV1), peroxisome proliferator-activated receptor (PPAR)-α and non-cannabinoid G-protein coupled receptors (GPRs) to mediate anti-inflammatory, immunomodulatory and neuroprotective activities. In vivo generation of the cannabinoid compounds is triggered by physiological and pathological stimuli and, specifically in the brain, mediates fine regulation of synaptic strength, neuroprotection, and resolution of neuroinflammation. Here, we review the role of the endocannabinoid system in intrinsic neuroprotective mechanisms and its therapeutic potential for the treatment of neuroinflammation and associated synaptopathy.
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Affiliation(s)
- Ludmila A. Kasatkina
- Otto Loewi Research Center, Division of Pharmacology, Medical University of Graz, 8010 Graz, Austria; (L.A.K.); (S.R.)
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Sonja Rittchen
- Otto Loewi Research Center, Division of Pharmacology, Medical University of Graz, 8010 Graz, Austria; (L.A.K.); (S.R.)
| | - Eva M. Sturm
- Otto Loewi Research Center, Division of Pharmacology, Medical University of Graz, 8010 Graz, Austria; (L.A.K.); (S.R.)
- Correspondence:
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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.
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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
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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.
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9
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Haspula D, Clark MA. Cannabinoid Receptors: An Update on Cell Signaling, Pathophysiological Roles and Therapeutic Opportunities in Neurological, Cardiovascular, and Inflammatory Diseases. Int J Mol Sci 2020; 21:E7693. [PMID: 33080916 PMCID: PMC7590033 DOI: 10.3390/ijms21207693] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 10/14/2020] [Accepted: 10/15/2020] [Indexed: 12/16/2022] Open
Abstract
The identification of the human cannabinoid receptors and their roles in health and disease, has been one of the most significant biochemical and pharmacological advancements to have occurred in the past few decades. In spite of the major strides made in furthering endocannabinoid research, therapeutic exploitation of the endocannabinoid system has often been a challenging task. An impaired endocannabinoid tone often manifests as changes in expression and/or functions of type 1 and/or type 2 cannabinoid receptors. It becomes important to understand how alterations in cannabinoid receptor cellular signaling can lead to disruptions in major physiological and biological functions, as they are often associated with the pathogenesis of several neurological, cardiovascular, metabolic, and inflammatory diseases. This review focusses mostly on the pathophysiological roles of type 1 and type 2 cannabinoid receptors, and it attempts to integrate both cellular and physiological functions of the cannabinoid receptors. Apart from an updated review of pre-clinical and clinical studies, the adequacy/inadequacy of cannabinoid-based therapeutics in various pathological conditions is also highlighted. Finally, alternative strategies to modulate endocannabinoid tone, and future directions are also emphasized.
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Affiliation(s)
- Dhanush Haspula
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA;
| | - Michelle A. Clark
- Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33314, USA
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10
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Carullo G, Federico S, Relitti N, Gemma S, Butini S, Campiani G. Retinitis Pigmentosa and Retinal Degenerations: Deciphering Pathways and Targets for Drug Discovery and Development. ACS Chem Neurosci 2020; 11:2173-2191. [PMID: 32589402 DOI: 10.1021/acschemneuro.0c00358] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Inherited retinal diseases (IRDs) are a group of retinopathies generally caused by genetic mutations. Retinitis pigmentosa (RP) represents one of the most studied IRDs. RP leads to intense vision loss or blindness resulting from the degeneration of photoreceptor cells. To date, RP is mainly treated with palliative supplementation of vitamin A and retinoids, gene therapies, or surgical interventions. Therefore, a pharmacologically based therapy is an urgent need requiring a medicinal chemistry approach, to validate molecular targets able to deal with retinal degeneration. This Review aims at outlining the recent research efforts in identifying new drug targets for RP, especially focusing on the neuroprotective role of the Wnt/β-catenin/GSK3β pathway and apoptosis modulators (in particular PARP-1) but also on growth factors such as VEGF and BDNF. Furthermore, the role of spatiotemporally expressed G protein-coupled receptors (GPR124) in the retina and the emerging function of histone deacetylase inhibitors in promoting retinal neuroprotection will be discussed.
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Affiliation(s)
- Gabriele Carullo
- Department of Biotechnology, Chemistry and Pharmacy, Department of Excellence 2018−2022, University of Siena, via Aldo Moro 2, 53100 Siena, Italy
| | - Stefano Federico
- Department of Biotechnology, Chemistry and Pharmacy, Department of Excellence 2018−2022, University of Siena, via Aldo Moro 2, 53100 Siena, Italy
| | - Nicola Relitti
- Department of Biotechnology, Chemistry and Pharmacy, Department of Excellence 2018−2022, University of Siena, via Aldo Moro 2, 53100 Siena, Italy
| | - Sandra Gemma
- Department of Biotechnology, Chemistry and Pharmacy, Department of Excellence 2018−2022, University of Siena, via Aldo Moro 2, 53100 Siena, Italy
| | - Stefania Butini
- Department of Biotechnology, Chemistry and Pharmacy, Department of Excellence 2018−2022, University of Siena, via Aldo Moro 2, 53100 Siena, Italy
| | - Giuseppe Campiani
- Department of Biotechnology, Chemistry and Pharmacy, Department of Excellence 2018−2022, University of Siena, via Aldo Moro 2, 53100 Siena, Italy
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11
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Abstract
Cannabis ranks among the most commonly used psychotropic drugs worldwide. In the context of the global movement toward more widespread legalisation, there is a growing need toward developing a better understanding of the physiological and pathological effects. We provide an overview of the current evidence on the effects of cannabinoids on the eye. Of the identified cannabinoids, Δ9-tetrahydrocannabinol is recognized to be the primary psychotropic compound, and cannabidiol is the predominant nonpsychoactive ingredient. Despite demonstrating ocular hypotensive and neuroprotective activity, the use of cannabinoids as a treatment for glaucoma is limited by a large number of potential systemic and ophthalmic side effects. Anterior segment effects of cannabinoids are complex, with preliminary evidence showing decreased corneal endothelial density in chronic cannabinoid users. Experiments in rodents, however, have shown potential promise for the treatment of ocular surface injury via antinociceptive and antiinflammatory effects. Electroretinography studies demonstrating adverse effects on photoreceptor, bipolar, and ganglion cell function suggest links between cannabis and neuroretinal dysfunction. Neuro-ophthalmic associations include ocular motility deficits and decrements in smooth pursuit and saccadic eye movements, although potential therapeutic effects for congenital and acquired nystagmus have been observed.
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12
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An D, Peigneur S, Hendrickx LA, Tytgat J. Targeting Cannabinoid Receptors: Current Status and Prospects of Natural Products. Int J Mol Sci 2020; 21:E5064. [PMID: 32709050 PMCID: PMC7404216 DOI: 10.3390/ijms21145064] [Citation(s) in RCA: 94] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 07/14/2020] [Accepted: 07/15/2020] [Indexed: 02/07/2023] Open
Abstract
Cannabinoid receptors (CB1 and CB2), as part of the endocannabinoid system, play a critical role in numerous human physiological and pathological conditions. Thus, considerable efforts have been made to develop ligands for CB1 and CB2, resulting in hundreds of phyto- and synthetic cannabinoids which have shown varying affinities relevant for the treatment of various diseases. However, only a few of these ligands are clinically used. Recently, more detailed structural information for cannabinoid receptors was revealed thanks to the powerfulness of cryo-electron microscopy, which now can accelerate structure-based drug discovery. At the same time, novel peptide-type cannabinoids from animal sources have arrived at the scene, with their potential in vivo therapeutic effects in relation to cannabinoid receptors. From a natural products perspective, it is expected that more novel cannabinoids will be discovered and forecasted as promising drug leads from diverse natural sources and species, such as animal venoms which constitute a true pharmacopeia of toxins modulating diverse targets, including voltage- and ligand-gated ion channels, G protein-coupled receptors such as CB1 and CB2, with astonishing affinity and selectivity. Therefore, it is believed that discovering novel cannabinoids starting from studying the biodiversity of the species living on planet earth is an uncharted territory.
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Affiliation(s)
| | | | | | - Jan Tytgat
- Toxicology and Pharmacology, KU Leuven, Campus Gasthuisberg, O&N 2, Herestraat 49, P.O. Box 922, 3000 Leuven, Belgium; (D.A.); (S.P.); (L.A.H.)
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13
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Hommer N, Kallab M, Szegedi S, Puchner S, Stjepanek K, Bauer M, Werkmeister RM, Schmetterer L, Abensperg‐Traun M, Garhöfer G, Schmidl D. The Effect of Orally Administered Dronabinol on Optic Nerve Head Blood Flow in Healthy Subjects-A Randomized Clinical Trial. Clin Pharmacol Ther 2020; 108:155-161. [PMID: 31977076 PMCID: PMC7325313 DOI: 10.1002/cpt.1797] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 01/04/2020] [Indexed: 02/04/2023]
Abstract
It has been hypothesized that besides its intraocular pressure (IOP) lowering potential, tetrahydrocannabinol (THC) may also improve ocular hemodynamics. The aim of the present study was to investigate whether single oral administration of dronabinol, a synthetic THC, alters optic nerve head blood flow (ONHBF) and its regulation in healthy subjects. The study was carried out in a randomized, placebo-controlled, double-masked, two-way crossover design in 24 healthy subjects. For each study participant, 2 study days were scheduled, on which they either received capsules containing 5 mg dronabinol or placebo. ONHBF was measured with laser Doppler flowmetry at rest and while the study participants performed isometric exercise for 6 minutes to increase mean arterial blood pressure (MAP). This was repeated 1 hour after drug intake. Ocular perfusion pressure (OPP) was calculated as 2/3MAP-IOP. Dronabinol was well tolerated and no cannabinoid-related psychoactive effects were reported. Neither administration of dronabinol nor placebo had an effect on IOP, MAP, or OPP. In contrast, dronabinol significantly increased ONHBF at rest by 9.5 ± 8.1%, whereas placebo did not show a change in ONHBF (0.3 ± 7.4% vs. baseline, P < 0.001 between study days). Dronabinol did not alter the autoregulatory response of ONHBF to isometric exercise. In conclusion, the present data indicate that low-dose dronabinol increases ONHBF in healthy subjects without affecting IOP, OPP, or inducing psychoactive side effects. In addition, dronabinol does not alter the autoregulatory response of ONHBF to an experimental increase in OPP. Further studies are needed to investigate whether this effect can also be observed in patients with glaucoma.
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Affiliation(s)
- Nikolaus Hommer
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
| | - Martin Kallab
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
| | - Stephan Szegedi
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
| | - Stefan Puchner
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
| | - Kristina Stjepanek
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
| | - Martin Bauer
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
| | - René M. Werkmeister
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
| | - Leopold Schmetterer
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
- Singapore Eye Research InstituteSingaporeSingapore
- Lee Kong Chian School of MedicineNanyang Technological UniversitySingaporeSingapore
- Ophthalmology and Visual Sciences Academic Clinical ProgramDuke‐NUS Medical SchoolSingaporeSingapore
- SERI‐NTU Advanced Ocular Engineering (STANCE)SingaporeSingapore
- Institute of OphthalmologyBaselSwitzerland
| | | | - Gerhard Garhöfer
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
| | - Doreen Schmidl
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
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14
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Liu X, Liu Y, Cao Q, Wu Y, Huo X, Du X, Chen Z. Impact of age on N-methyl-N-nitrosourea induced microsatellite instability in young and old C57BL/6J mice. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2020; 853:503189. [PMID: 32522351 DOI: 10.1016/j.mrgentox.2020.503189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 03/20/2020] [Accepted: 03/27/2020] [Indexed: 10/24/2022]
Abstract
Age is an important factor in the evaluation of chemical toxicology. Chemical carcinogenic compounds can induce genomic mutations. However, few studies have been conducted on the association between genomic mutation frequency, such as microsatellite instability (MSI), and the age of mice treated with a nitrosourea mutagen. In the current work, we treated young (6 weeks) and old (10 months) mice with N-methyl-N-nitrosourea (MNU) for 4 months; the MSI frequency was then measured using polymerase chain reaction (PCR) and short tandem repeat (STR) scanning. The percentage of animals with MSI in the old group was significantly higher than that in the young group (100% and 75%). The frequency of MSI events was significantly different between the two groups as well (15.8% for old and 9.4% for young). The ratio of MSI loci displayed no obvious difference between the two groups. In addition, a few loci, including D15Mit5 and D8Mit14 exhibited the highest frequency of MSI events. Since specific loci showed increased MSI in the present study and a higher frequency in previous studies, these loci could be regarded as "hot spot". These results suggested that old mice would be more susceptible to this mutagen, and prone to accrue MSI. The hot spot microsatellite loci are potentially useful markers for genomic instability analysis.
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Affiliation(s)
- Xingchen Liu
- School of Basic Medical Sciences, Capital Medical University, Beijing Key Laboratory of Cancer Invasion & Metastasis Research, Beijing 100069, China
| | - Yihan Liu
- School of Basic Medical Sciences, Capital Medical University, Beijing Key Laboratory of Cancer Invasion & Metastasis Research, Beijing 100069, China
| | - Qi Cao
- School of Basic Medical Sciences, Capital Medical University, Beijing Key Laboratory of Cancer Invasion & Metastasis Research, Beijing 100069, China
| | - Ying Wu
- School of Basic Medical Sciences, Capital Medical University, Beijing Key Laboratory of Cancer Invasion & Metastasis Research, Beijing 100069, China
| | - Xueyun Huo
- School of Basic Medical Sciences, Capital Medical University, Beijing Key Laboratory of Cancer Invasion & Metastasis Research, Beijing 100069, China
| | - Xiaoyan Du
- School of Basic Medical Sciences, Capital Medical University, Beijing Key Laboratory of Cancer Invasion & Metastasis Research, Beijing 100069, China.
| | - Zhenwen Chen
- School of Basic Medical Sciences, Capital Medical University, Beijing Key Laboratory of Cancer Invasion & Metastasis Research, Beijing 100069, China
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15
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Zantut PRA, Veras MM, Yariwake VY, Takahashi WY, Saldiva PH, Young LH, Damico FM, Fajersztajn L. Effects of cannabis and its components on the retina: a systematic review. Cutan Ocul Toxicol 2019; 39:1-9. [PMID: 31648567 DOI: 10.1080/15569527.2019.1685534] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Purpose: Cannabis is the most prevalent drug in the world and its consumption is growing. Cannabinoid receptors are present in the human central nervous system. Recent studies show evidence of the effects of cannabinoids on the retina, and synthesising the results of these studies may be relevant for ophthalmologists. Thus, this review adopts standardised, systematic review methodology to investigate the effects of exposure to cannabis and components on the retina.Methods: We searched five online databases for the combined terms for outcome ("retina") and exposure ("cannabis"). Eligibility of studies were conducted by two independent reviewers, and risk of bias was assessed.Results: We retrieved 495 studies, screened 229 studies, assessed 52 studies for eligibility, and included 16 studies for qualitative analysis. The cannabinoids most frequently investigated were delta-9-tetrahydrocannabinol (THC), abnormal cannabidiol, synthetic cannabinoid, and cannabidiol (CDB). The outcomes most studied were neuroretinal dysfunction, followed by vascular effects. The studies also included investigation of neuroprotective and anti-inflammatory effects and teratogenic effects.Conclusions: This review suggests that cannabinoids may have an important role in retinal processing and function.
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Affiliation(s)
- Paulo R A Zantut
- Department of Ophthalmology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Mariana M Veras
- Laboratory of Experimental Air Pollution (LIM05), Department of Pathology, Faculdade de Medicina da Universidade São Paulo, São Paulo, Brazil
| | - Victor Y Yariwake
- Laboratory of Experimental Air Pollution (LIM05), Department of Pathology, Faculdade de Medicina da Universidade São Paulo, São Paulo, Brazil
| | - Walter Y Takahashi
- Department of Ophthalmology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Paulo H Saldiva
- Laboratory of Experimental Air Pollution (LIM05), Department of Pathology, Faculdade de Medicina da Universidade São Paulo, São Paulo, Brazil.,Institute for Advanced Studies of the University of São Paulo-IEA, Universidade de São Paulo, São Paulo, Brazil
| | - Lucy H Young
- Department of Ophthalmology, Harvard Medical School, Cambridge, MA, USA
| | - Francisco Max Damico
- Department of Ophthalmology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Laís Fajersztajn
- Institute for Advanced Studies of the University of São Paulo-IEA, Universidade de São Paulo, São Paulo, Brazil.,Department Global Brain Health Institute, University of California, San Francisco, CA, USA
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16
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Freitas HR, Reis RAM, Ventura ALM, França GR. Interaction between cannabinoid and nucleotide systems as a new mechanism of signaling in retinal cell death. Neural Regen Res 2019; 14:2093-2094. [PMID: 31397346 PMCID: PMC6788250 DOI: 10.4103/1673-5374.262585] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Hércules R Freitas
- Laboratory of Neurochemistry, Institute of Biophysics Carlos Chagas Filho, Universidade Federal do Rio de Janeiro; School of Health Sciences, Centro Universitário IBMR, Rio de Janeiro, RJ, Brazil
| | - Ricardo A M Reis
- Laboratory of Neurochemistry, Institute of Biophysics Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Ana L M Ventura
- Laboratory of Neurochemistry, Institute of Biology, Universidade Federal Fluminense, Niterói, RJ, Brazil
| | - Guilherme R França
- Laboratory of Neurochemistry, Institute of Biology, Universidade Federal Fluminense, Niterói; Biomedical Institute, Departament of Physiological Sciences/Pharmacology, Universidade Federal do Estado do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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17
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Papadogkonaki S, Theodorakis Κ, Thermos K. Endogenous and synthetic cannabinoids induce the downregulation of cannabinoid CB1 receptor in retina. Exp Eye Res 2019; 185:107694. [DOI: 10.1016/j.exer.2019.107694] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/20/2019] [Accepted: 06/10/2019] [Indexed: 10/26/2022]
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18
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The Endocannabinoid System Is Present in Rod Outer Segments from Retina and Is Modulated by Light. Mol Neurobiol 2019; 56:7284-7295. [PMID: 31016476 DOI: 10.1007/s12035-019-1603-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 04/10/2019] [Indexed: 10/27/2022]
Abstract
The aim of the present research was to evaluate if the endocannabinoid system (enzymes and receptors) could be modulated by light in rod outer segment (ROS) from bovine retina. First, we analyzed endocannabinoid 2-arachidonoylglycerol (2-AG) metabolism in purified ROS obtained from dark-adapted (DROS) or light-adapted (LROS) retinas. To this end, diacylglycerol lipase (DAGL), monoacylglycerol lipase (MAGL), and lysophosphatidate phosphohydrolase (LPAP) enzymatic activities were analyzed using radioactive substrates. The protein content of these enzymes and of the receptors to which cannabinoids bind was determined by immunoblotting under light stimulus. Our results indicate that whereas DAGL and MAGL activities were stimulated in retinas exposed to light, no changes were observed in LPAP activity. Interestingly, the protein content of the main enzymes involved in 2-AG metabolism, phospholipase C β1 (PLCβ1), and DAGLα (synthesis), and MAGL (hydrolysis), was also modified by light. PLCβ1 content was increased, while that of lipases was decreased. On the other hand, light produced an increase in the cannabinoid receptors CB1 and CB2 and a decrease in GPR55 protein levels. Taken together, our results indicate that the endocannabinoid system (enzymes and receptors) depends on the illumination state of the retina, suggesting that proteins related to phototransduction phenomena could be involved in the effects observed.
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