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Rusciano D, Russo C. The Therapeutic Trip of Melatonin Eye Drops: From the Ocular Surface to the Retina. Pharmaceuticals (Basel) 2024; 17:441. [PMID: 38675402 PMCID: PMC11054783 DOI: 10.3390/ph17040441] [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: 03/04/2024] [Revised: 03/18/2024] [Accepted: 03/27/2024] [Indexed: 04/28/2024] Open
Abstract
Melatonin is a ubiquitous molecule found in living organisms, ranging from bacteria to plants and mammals. It possesses various properties, partly due to its robust antioxidant nature and partly owed to its specific interaction with melatonin receptors present in almost all tissues. Melatonin regulates different physiological functions and contributes to the homeostasis of the entire organism. In the human eye, a small amount of melatonin is also present, produced by cells in the anterior segment and the posterior pole, including the retina. In the eye, melatonin may provide antioxidant protection along with regulating physiological functions of ocular tissues, including intraocular pressure (IOP). Therefore, it is conceivable that the exogenous topical administration of sufficiently high amounts of melatonin to the eye could be beneficial in several instances: for the treatment of eye pathologies like glaucoma, due to the IOP-lowering and neuroprotection effects of melatonin; for the prevention of other dysfunctions, such as dry eye and refractive defects (cataract and myopia) mainly due to its antioxidant properties; for diabetic retinopathy due to its metabolic influence and neuroprotective effects; for macular degeneration due to the antioxidant and neuroprotective properties; and for uveitis, mostly owing to anti-inflammatory and immunomodulatory properties. This paper reviews the scientific evidence supporting the use of melatonin in different ocular districts. Moreover, it provides data suggesting that the topical administration of melatonin as eye drops is a real possibility, utilizing nanotechnological formulations that could improve its solubility and permeation through the eye. This way, its distribution and concentration in different ocular tissues may support its pleiotropic therapeutic effects.
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Affiliation(s)
- Dario Rusciano
- Fidia Research Centre, c/o University of Catania, Via Santa Sofia 89, 95123 Catania, Italy
| | - Cristina Russo
- Department of Biomedical and Biotechnological Sciences, University of Catania, Via Santa Sofia 89, 95123 Catania, Italy;
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2
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Mueller A, Lam I, Kishor K, Lee RK, Bhattacharya S. Secondary glaucoma: Toward interventions based on molecular underpinnings. WIREs Mech Dis 2024; 16:e1628. [PMID: 37669762 DOI: 10.1002/wsbm.1628] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 08/08/2023] [Accepted: 08/10/2023] [Indexed: 09/07/2023]
Abstract
Glaucoma is a heterogeneous group of progressive diseases that leads to irreversible blindness. Secondary glaucoma refers to glaucoma caused by a known underlying condition. Pseudoexfoliation and pigment dispersion syndromes are common causes of secondary glaucoma. Their respective deposits may obstruct the trabecular meshwork, leading to aqueous humor outflow resistance, ocular hypertension, and optic neuropathy. There are no disease-specific interventions available for either. Pseudoexfoliation syndrome is characterized by fibrillar deposits (pseudoexfoliative material) on anterior segment structures. Over a decade of multiomics analyses taken together with the current knowledge on pseudoexfoliative glaucoma warrant a re-think of mechanistic possibilities. We propose that the presence of nucleation centers (e.g., vitamin D binding protein), crosslinking enzymes (e.g., transglutaminase 2), aberrant extracellular matrix, flawed endocytosis, and abnormal aqueous-blood barrier contribute to the formation of proteolytically resistant pseudoexfoliative material. Pigment dispersion syndrome is characterized by abnormal iridolenticular contact that disrupts iris pigment epithelium and liberates melanin granules. Iris melanogenesis is aberrant in this condition. Cytotoxic melanogenesis intermediates leak out of melanosomes and cause iris melanocyte and pigment epithelium cell death. Targeting melanogenesis can likely decrease the risk of pigmentary glaucoma. Skin and melanoma research provides insights into potential therapeutics. We propose that specific prostanoid agonists and fenofibrates may reduce melanogenesis by inhibiting cholesterol internalization and de novo synthesis. Additionally, melatonin is a potent melanogenesis suppressor, antioxidant, and hypotensive agent, rendering it a valuable agent for pigmentary glaucoma. In pseudoexfoliative glaucoma, where environmental insults drive pseudoexfoliative material formation, melatonin's antioxidant and hypotensive properties may offer adjunct therapeutic benefits. This article is categorized under: Neurological Diseases > Molecular and Cellular Physiology.
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Affiliation(s)
- Anna Mueller
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
- Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, USA
| | - Isabel Lam
- Idaho College of Osteopathic Medicine, Meridian, Idaho, USA
| | - Krishna Kishor
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
- Miami Integrative Metabolomics Research Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Richard K Lee
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
- Miami Integrative Metabolomics Research Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Sanjoy Bhattacharya
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
- Miami Integrative Metabolomics Research Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
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3
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Borges VG, Gabriel JE. Assessment of melatonin-alpha adrenergic receptor complexes by molecular docking analysis. BRAZ J BIOL 2022; 82:e261624. [PMID: 35920463 DOI: 10.1590/1519-6984.261624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 07/23/2022] [Indexed: 11/21/2022] Open
Abstract
The pineal melatonin (N-acetyl-5-methoxytryptamine) is a molecule associated in a way or another with probably all physiological systems, aiming to fulfil its functional integrative roles in central nervous system activity, sleep and wakefulness cycles, energy metabolism and thermoregulation, immune, reproductive, endocrine, cardiovascular, respiratory and excretory systems. Within this context, the present study aimed to assess in silico the formation of complexes between ligand melatonin and other potential receptor proteins by molecular docking analyses. The main steps established in this experimental procedure were: a) search and selection of the 3D structure of the melatonin from DrugBank; b) search and selection of 3D structures of other target receptor proteins using STRING, protein BLAST and database PDB; and c) formation of the complexes between melatonin and receptors selected using AutoDock4.0 server by molecular docking analyses. High reliability score and significant similarity were only identified between type 1B melatonin and alpha-2A adrenergic receptor. Thus, molecular docking assays were carried out using ligand melatonin and crystallographic structures of the alpha-2A adrenergic receptor coupled to an antagonist (ID PDB 6kux) and a partial agonist (ID PDB 6kuy) available in the database PDB. Binding energy values of -6.79 and -6.98 kcal/mol and structural stability by non-covalent intermolecular interactions were predicted during the formation of complexes between melatonin and alpha-2A adrenergic receptor 6kux and 6kuy, respectively. In this way, the findings described in current study may indicate strong interactions between melatonin and adrenoceptors, suggesting its possible partial agonist effect on the activation of the alfa-2A adrenergic receptor.
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Affiliation(s)
- V G Borges
- Universidade Federal de São Carlos - UFSCar, Curso de Graduação de Bacharelado em Biotecnologia, São Carlos, SP, Brasil
| | - J E Gabriel
- Universidade Federal de São Carlos - UFSCar, Centro de Ciências da Saúde e Biológicas - CCBS, Departamento de Hidrobiologia, São Carlos, SP, Brasil
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Influence of Circadian Rhythm in the Eye: Significance of Melatonin in Glaucoma. Biomolecules 2021; 11:biom11030340. [PMID: 33668357 PMCID: PMC7996162 DOI: 10.3390/biom11030340] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 02/19/2021] [Accepted: 02/20/2021] [Indexed: 02/07/2023] Open
Abstract
Circadian rhythm and the molecules involved in it, such as melanopsin and melatonin, play an important role in the eye to regulate the homeostasis and even to treat some ocular conditions. As a result, many ocular pathologies like dry eye, corneal wound healing, cataracts, myopia, retinal diseases, and glaucoma are affected by this cycle. This review will summarize the current scientific literature about the influence of circadian patterns on the eye, focusing on its relationship with increased intraocular pressure (IOP) fluctuations and glaucoma. Regarding treatments, two ways should be studied: the first one, to analyze if some treatments could improve their effect on the ocular disease when their posology is established in function of circadian patterns, and the second one, to evaluate new drugs to treat eye pathologies related to the circadian rhythm, as it has been stated with melatonin or its analogs, that not only could be used as the main treatment but as coadjutant, improving the circadian pattern or its antioxidant and antiangiogenic properties.
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A Topical Formulation of Melatoninergic Compounds Exerts Strong Hypotensive and Neuroprotective Effects in a Rat Model of Hypertensive Glaucoma. Int J Mol Sci 2020; 21:ijms21239267. [PMID: 33291737 PMCID: PMC7730513 DOI: 10.3390/ijms21239267] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/23/2020] [Accepted: 12/02/2020] [Indexed: 02/08/2023] Open
Abstract
Melatonin is of great importance for regulating several eye processes, including pressure homeostasis. Melatonin in combination with agomelatine has been recently reported to reduce intraocular pressure (IOP) with higher efficacy than each compound alone. Here, we used the methylcellulose (MCE) rat model of hypertensive glaucoma, an optic neuropathy characterized by the apoptotic death of retinal ganglion cells (RGCs), to evaluate the hypotensive and neuroprotective efficacy of an eye drop nanomicellar formulation containing melatonin/agomelatine. Eye tissue distribution of melatonin/agomelatine in healthy rats was evaluated by HPLC/MS/MS. In the MCE model, we assessed by tonometry the hypotensive efficacy of melatonin/agomelatine. Neuroprotection was revealed by electroretinography; by levels of inflammatory and apoptotic markers; and by RGC density. The effects of melatonin/agomelatine were compared with those of timolol (a beta blocker with prevalent hypotensive activity) or brimonidine (an alpha 2 adrenergic agonist with potential neuroprotective efficacy), two drugs commonly used to treat glaucoma. Both melatonin and agomelatine penetrate the posterior segment of the eye. In the MCE model, IOP elevation was drastically reduced by melatonin/agomelatine with higher efficacy than that of timolol or brimonidine. Concomitantly, gliosis-related inflammation and the Bax-associated apoptosis were partially prevented, thus leading to RGC survival and recovered retinal dysfunction. We suggest that topical melatoninergic compounds might be beneficial for ocular health.
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Natural Products: Evidence for Neuroprotection to Be Exploited in Glaucoma. Nutrients 2020; 12:nu12103158. [PMID: 33081127 PMCID: PMC7602834 DOI: 10.3390/nu12103158] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 10/12/2020] [Accepted: 10/14/2020] [Indexed: 12/14/2022] Open
Abstract
Glaucoma, a leading cause of irreversible blindness worldwide, is an optic neuropathy characterized by the progressive death of retinal ganglion cells (RGCs). Elevated intraocular pressure (IOP) is recognized as the main risk factor. Despite effective IOP-lowering therapies, the disease progresses in a significant number of patients. Therefore, alternative IOP-independent strategies aiming at halting or delaying RGC degeneration is the current therapeutic challenge for glaucoma management. Here, we review the literature on the neuroprotective activities, and the underlying mechanisms, of natural compounds and dietary supplements in experimental and clinical glaucoma.
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Hypotensive Effect of Nanomicellar Formulation of Melatonin and Agomelatine in a Rat Model: Significance for Glaucoma Therapy. Diagnostics (Basel) 2020; 10:diagnostics10030138. [PMID: 32138160 PMCID: PMC7151109 DOI: 10.3390/diagnostics10030138] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 02/18/2020] [Accepted: 02/28/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Melatoninergic agents are known to reduce intraocular pressure (IOP). The present study was performed to evaluate the effect of nanomicellar formulations of melatoninergic agents on IOP in the rat. METHODS Tonometry was used to measure IOP in eyes instilled with melatonin or agomelatine. Ocular hypertension was induced by the injection of methylcellulose in the anterior chamber. RESULTS Melatonin formulated in nanomicelles had a longer lasting hypotonizing effect on IOP with respect to melatonin in saline. Nanomicellar formulations of melatonin and agomelatine, either alone or in combination, had lowering effects that did not depend on their concentration or their combination, which, however, resulted in an increased duration of the hypotonizing effect. The duration of the lowering effect was further increased by the addition of lipoic acid. CONCLUSIONS We demonstrated the effective hypotonizing activity of melatonin and agomelatine in combination with lipoic acid. Although results in animals cannot be directly translated to humans, the possibility of developing novel therapeutical approaches for patients suffering from hypertensive glaucoma should be considered.
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Alkozi HA, Navarro G, Franco R, Pintor J. Melatonin and the control of intraocular pressure. Prog Retin Eye Res 2019; 75:100798. [PMID: 31560946 DOI: 10.1016/j.preteyeres.2019.100798] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 09/13/2019] [Accepted: 09/18/2019] [Indexed: 12/15/2022]
Abstract
Melatonin is not only synthesized by the pineal gland but by several ocular structures. This natural indoleamine is of great importance for regulating several eye processes, among which pressure homeostasis is included. Glaucoma, the most prevalent eye disease, also known as the silent thief of vision, is a multifactorial pathology that is associated to age and, often, to intraocular hypertension (IOP). Indeed IOP is the only modifiable risk factor and as such medications are available to control it; however, novel medications are sought to minimize undesirable side effects. Melatonin and analogues decrease IOP in both normotensive and hypertensive eyes. Melatonin activates its cognate membrane receptors, MT1 and MT2, which are present in numerous ocular tissues, including the aqueous-humor-producing ciliary processes. Melatonin receptors belong to the superfamily of G-protein-coupled receptors and their activation would lead to different signalling pathways depending on the tissue. This review describes the molecular mechanisms underlying differential functionalities that are attributed to melatonin receptors. Accordingly, the current work highlights the important role of melatonin and its analogues in the healthy and in the glaucomatous eyes, with special attention to the control of intraocular pressure.
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Affiliation(s)
- Hanan Awad Alkozi
- Department of Biochemistry and Molecular Biology, Faculty of Optics and Optometry, University Complutense of Madrid, Madrid, Spain
| | - Gemma Navarro
- Centro de Investigación en Red, Enfermedades Neurodegeneratives (CiberNed), Instituto de Salud Carlos III, Sinesio Delgado 6, 28029, Madrid, Spain; Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Universitat de Barcelona, Avda. Juan XXIII, 27, 08027, Barcelona, Spain
| | - Rafael Franco
- Centro de Investigación en Red, Enfermedades Neurodegeneratives (CiberNed), Instituto de Salud Carlos III, Sinesio Delgado 6, 28029, Madrid, Spain; Department of Biochemistry and Molecular Biomedicine, School of Biology, Universitat de Barcelona, Diagonal 643, 08028, Barcelona, Barcelona, Spain.
| | - Jesus Pintor
- Department of Biochemistry and Molecular Biology, Faculty of Optics and Optometry, University Complutense of Madrid, Madrid, Spain; Real Academia Nacional de Farmacia, Calle Farmacia 11, 28004, Madrid, Spain.
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Guglielmi P, Carradori S, Campestre C, Poce G. Novel therapies for glaucoma: a patent review (2013-2019). Expert Opin Ther Pat 2019; 29:769-780. [DOI: 10.1080/13543776.2019.1653279] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Paolo Guglielmi
- Department of Chemistry and Technologies of Drugs, Sapienza University of Rome, Rome, Italy
| | - Simone Carradori
- Department of Pharmacy, University “G. d’Annunzio” of Chieti-Pescara, Chieti, Italy
| | - Cristina Campestre
- Department of Pharmacy, University “G. d’Annunzio” of Chieti-Pescara, Chieti, Italy
| | - Giovanna Poce
- Department of Chemistry and Technologies of Drugs, Sapienza University of Rome, Rome, Italy
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Navarro Gil FJ, Huete-Toral F, Crooke A, Dominguez Godinez CO, Carracedo G, Pintor J. Effect of Melatonin and Its Analogs on Tear Secretion. J Pharmacol Exp Ther 2019; 371:186-190. [PMID: 31371479 DOI: 10.1124/jpet.119.259192] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 07/30/2019] [Indexed: 11/22/2022] Open
Abstract
Melatonin has been shown to enhance tear secretion associated with dinucleotide diadenosine tetraphosphate. This study investigated the isolated action of melatonin and its analogs, agomelatine, N-butanoyl-2-(2-methoxy-6H-isoindolo[2,1-a]indol-11-yl) ethanamine (IIK7), and 5-methoxycarbonylamino-N-cetyltryptamine (5-MCA-NAT) (10 µl at 100 µM), on tear secretion when applied topically in the rabbit cornea and its relationship with the melatonin MT1, MT2, and MT3/quinone reductase QR2 receptors. The results showed a significant increase in tear secretion, with a maximal effect at 60 minutes for the agonists (138.9% ± 6.5%, 128.9% ± 6.4%, and 120.0% ± 5.2%, respectively; P < 0.05; 100% control) but not for melatonin (101.6% ± 7.9%; P > 0.05). Agonist action was tested combined with the antagonists DH97 (MT2 selective), prazosin (MT3/QR2 inhibitor), and luzindole (nonselective MT membrane receptor) (10 µl at 100 µM). DH97 reversed the effect of agomelatine, IIK7, and 5-MCA-NAT up to 30.85% ± 7.6%,108% ± 7.2%, and 87.01% ± 7.6%, respectively (P < 0.05; 100% control). Luzindole antagonized agomelatine and 5-MCA-NAT up to 67.35% ± 7.6% and 92.12% ± 8%, respectively (P < 0.05). Prazosin only reversed 5-MCA-NAT action up to 84.2% ± 7.7% (P < 0.05). These results suggest different pathways for the agonists to act through MT membrane receptors. Therefore, agomelatine, IIK7, and 5-MCA-NAT act through MT membrane receptors as secretagogues of tear secretion, and these analogs could be considered excellent therapeutic candidates for dry eye treatment. SIGNIFICANCE STATEMENT: Currently, dry eye with aqueous deficit is treated by adding artificial tears palliatively. This study shows that topical installation of three melatonin analogs (agomelatine, IIK7, and 5-MCA-NAT), but not melatonin, in therapeutic doses in the rabbit cornea significantly increases tear production, acting through different melatonin membrane receptor subtypes. Therefore, this study suggests that melatoninergic compounds could be considered excellent therapeutic candidates for dry eye treatment and ocular surface diseases occurring with a reduction in tear production.
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Affiliation(s)
- Francisco Javier Navarro Gil
- Departamentos de Optometría y Visión (F.J.N.G., C.O.D.G., G.C.) and Bioquímica y Biología Molecular (F.H.-T., A.C., J.P.), Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Madrid, Spain
| | - Fernando Huete-Toral
- Departamentos de Optometría y Visión (F.J.N.G., C.O.D.G., G.C.) and Bioquímica y Biología Molecular (F.H.-T., A.C., J.P.), Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Madrid, Spain
| | - Almudena Crooke
- Departamentos de Optometría y Visión (F.J.N.G., C.O.D.G., G.C.) and Bioquímica y Biología Molecular (F.H.-T., A.C., J.P.), Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Madrid, Spain
| | - Carmen Olalla Dominguez Godinez
- Departamentos de Optometría y Visión (F.J.N.G., C.O.D.G., G.C.) and Bioquímica y Biología Molecular (F.H.-T., A.C., J.P.), Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Madrid, Spain
| | - Gonzalo Carracedo
- Departamentos de Optometría y Visión (F.J.N.G., C.O.D.G., G.C.) and Bioquímica y Biología Molecular (F.H.-T., A.C., J.P.), Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Madrid, Spain
| | - Jesús Pintor
- Departamentos de Optometría y Visión (F.J.N.G., C.O.D.G., G.C.) and Bioquímica y Biología Molecular (F.H.-T., A.C., J.P.), Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Madrid, Spain
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Visser HE, Dees DD, Millichamp NJ, Vallone LV, Scott EM. Effect of orally administered melatonin on intraocular pressure of ophthalmologically normal dogs. Am J Vet Res 2019; 80:410-415. [PMID: 30919670 DOI: 10.2460/ajvr.80.4.410] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine the effect of orally administered melatonin on the intraocular pressure (IOP) of ophthalmologically normal dogs. ANIMALS 20 ophthalmologically normal dogs (40 eyes). PROCEDURES In a randomized crossover study, each dog received a 7-day regimen of melatonin (0.1 to 0.2 mg/kg, PO, q 12 h) and a placebo (150 mg of lactose powder in a capsule, PO, q 12 h), with a 7-day washout period between treatment regimens. Rebound tonometry was used to measure the IOP in both eyes of each dog 5 times at 2-hour intervals on days 0 (before administration of the first dose), 2, 4, and 7 (after administration of the last dose) of each treatment period. Repeated-measures ANOVA was used to evaluate the effects of treatment, day, and IOP measurement time within day on IOP. RESULTS Intraocular pressure was not significantly associated with treatment but was associated with day and the interaction between day and IOP measurement time within day. The mean ± SD IOP was 14.26 ± 2.95 and 14.34 ± 2.69 mm Hg for the melatonin and placebo regimens, respectively. Within each treatment period, the mean IOP tended to decrease from day 0 to 7 as well as within each day, which was attributed to the dogs becoming acclimated to the study protocol and natural diurnal variations in IOP. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that oral administration of melatonin (0.1 to 0.2 mg/kg, q 12 h for 7 d) did not significantly affect the IOP of ophthalmologically normal dogs.
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Melatonin Levels in Patients With Primary Open-angle Glaucoma With High or Low Intraocular Pressure. J Glaucoma 2019; 28:154-160. [DOI: 10.1097/ijg.0000000000001130] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Lledó VE, Alkozi HA, Pintor J. Yellow Filter Effect on Melatonin Secretion in the Eye: Role in IOP Regulation. Curr Eye Res 2019; 44:614-618. [PMID: 30640554 DOI: 10.1080/02713683.2019.1570276] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Purpose: Melatonin is a neurohormone mainly synthesized in the pineal gland; however, it is also present in the aqueous humor. One of melatonins' functions in the eye is the regulation of intraocular pressure (IOP). Melatonin is known to be sensitive to light. Recently, the photopigment which controls melatonin synthesis, melanopsin, was found in the crystalline lens. Therefore, light conditions are an interesting possible way of regulating melatonin levels in the aqueous humor. The current study used yellow filters, since melanopsin is activated by short wavelength (blue light). Methods: New Zealand white rabbits were used, divided in two groups, one under controlled 12 h light/dark cycles, while the rest had their cages encased with a yellow filter (λ 465-480). IOP measurements were taken every week at the same time before they were anesthetized for aqueous humor extraction. Results: Keeping the rabbits under the yellow filter resulted in a decrease in IOP up to 43.8 ± 7.8% after 3 weeks. This effect was reversed after the topical application of selective and nonselective melatonin receptors antagonists, 4PPDOT and luzindole. Also, blocking melanopsin by its antagonist AA92593 under white light condition decreased IOP. Finally, melatonin levels were found significantly higher in the aqueous humor of rabbits developed under yellow filter compared to controls (37.4 ± 4.2 and 15.3 ± 3.1 ng/ml, respectively). Conclusion: Yellow filters modulate melatonin levels in the aqueous humor due to deactivating melanopsin activity. This effect leads to a decrease in IOP mediated by melatonin receptors.
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Affiliation(s)
- Victoria Eugenia Lledó
- a Department of Biochemistry and Molecular Biology, Faculty of Optics and Optometry , University Complutense of Madrid , Madrid , Spain
| | - Hanan Awad Alkozi
- a Department of Biochemistry and Molecular Biology, Faculty of Optics and Optometry , University Complutense of Madrid , Madrid , Spain
| | - Jesús Pintor
- a Department of Biochemistry and Molecular Biology, Faculty of Optics and Optometry , University Complutense of Madrid , Madrid , Spain
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Boutin JA, Ferry G. Is There Sufficient Evidence that the Melatonin Binding SiteMT3Is Quinone Reductase 2? J Pharmacol Exp Ther 2018; 368:59-65. [DOI: 10.1124/jpet.118.253260] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 10/26/2018] [Indexed: 12/15/2022] Open
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Spadoni G, Bedini A, Furiassi L, Mari M, Mor M, Scalvini L, Lodola A, Ghidini A, Lucini V, Dugnani S, Scaglione F, Piomelli D, Jung KM, Supuran CT, Lucarini L, Durante M, Sgambellone S, Masini E, Rivara S. Identification of Bivalent Ligands with Melatonin Receptor Agonist and Fatty Acid Amide Hydrolase (FAAH) Inhibitory Activity That Exhibit Ocular Hypotensive Effect in the Rabbit. J Med Chem 2018; 61:7902-7916. [DOI: 10.1021/acs.jmedchem.8b00893] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Gilberto Spadoni
- Dipartimento di Scienze Biomolecolari, Università degli Studi di Urbino “Carlo Bo”, Piazza Rinascimento 6, I-61029 Urbino, Italy
| | - Annalida Bedini
- Dipartimento di Scienze Biomolecolari, Università degli Studi di Urbino “Carlo Bo”, Piazza Rinascimento 6, I-61029 Urbino, Italy
| | - Lucia Furiassi
- Dipartimento di Scienze Biomolecolari, Università degli Studi di Urbino “Carlo Bo”, Piazza Rinascimento 6, I-61029 Urbino, Italy
| | - Michele Mari
- Dipartimento di Scienze Biomolecolari, Università degli Studi di Urbino “Carlo Bo”, Piazza Rinascimento 6, I-61029 Urbino, Italy
| | - Marco Mor
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle Scienze 27/A I-43124 Parma, Italy
| | - Laura Scalvini
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle Scienze 27/A I-43124 Parma, Italy
| | - Alessio Lodola
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle Scienze 27/A I-43124 Parma, Italy
| | - Andrea Ghidini
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle Scienze 27/A I-43124 Parma, Italy
| | - Valeria Lucini
- Dipartimento di Oncologia ed Emato-Oncologia, Università degli Studi di Milano, Via Vanvitelli 32, I-20129 Milano, Italy
| | - Silvana Dugnani
- Dipartimento di Oncologia ed Emato-Oncologia, Università degli Studi di Milano, Via Vanvitelli 32, I-20129 Milano, Italy
| | - Francesco Scaglione
- Dipartimento di Oncologia ed Emato-Oncologia, Università degli Studi di Milano, Via Vanvitelli 32, I-20129 Milano, Italy
| | - Daniele Piomelli
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle Scienze 27/A I-43124 Parma, Italy
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California 92697, United States
| | - Kwang-Mook Jung
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California 92697, United States
| | - Claudiu T. Supuran
- Dipartimento NEUROFARBA, Sezione di Scienze Farmaceutiche e Nutraceutiche, Università degli Studi di Firenze, via Ugo Shiff 6, I-50019 Sesto Fiorentino (FI), Italy
| | - Laura Lucarini
- Dipartimento NEUROFARBA, Sezione di Farmacologia e Tossicologia, Università degli Studi di Firenze, Viale G. Pieraccini 6, I-50019 Firenze, Italy
| | - Mariaconcetta Durante
- Dipartimento NEUROFARBA, Sezione di Farmacologia e Tossicologia, Università degli Studi di Firenze, Viale G. Pieraccini 6, I-50019 Firenze, Italy
| | - Silvia Sgambellone
- Dipartimento NEUROFARBA, Sezione di Farmacologia e Tossicologia, Università degli Studi di Firenze, Viale G. Pieraccini 6, I-50019 Firenze, Italy
| | - Emanuela Masini
- Dipartimento NEUROFARBA, Sezione di Farmacologia e Tossicologia, Università degli Studi di Firenze, Viale G. Pieraccini 6, I-50019 Firenze, Italy
| | - Silvia Rivara
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle Scienze 27/A I-43124 Parma, Italy
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Sharif NA. iDrugs and iDevices Discovery Research: Preclinical Assays, Techniques, and Animal Model Studies for Ocular Hypotensives and Neuroprotectants. J Ocul Pharmacol Ther 2018; 34:7-39. [PMID: 29323613 DOI: 10.1089/jop.2017.0125] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Discovery ophthalmic research is centered around delineating the molecular and cellular basis of ocular diseases and finding and exploiting molecular and genetic pathways associated with them. From such studies it is possible to determine suitable intervention points to address the disease process and hopefully to discover therapeutics to treat them. An investigational new drug (IND) filing for a new small-molecule drug, peptide, antibody, genetic treatment, or a device with global health authorities requires a number of preclinical studies to provide necessary safety and efficacy data. Specific regulatory elements needed for such IND-enabling studies are beyond the scope of this article. However, to enhance the overall data packages for such entities and permit high-quality foundation-building publications for medical affairs, additional research and development studies are always desirable. This review aims to provide examples of some target localization/verification, ocular drug discovery processes, and mechanistic and portfolio-enhancing exploratory investigations for candidate drugs and devices for the treatment of ocular hypertension and glaucomatous optic neuropathy (neurodegeneration of retinal ganglion cells and their axons). Examples of compound screening assays, use of various technologies and techniques, deployment of animal models, and data obtained from such studies are also presented.
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Affiliation(s)
- Najam A Sharif
- 1 Global Alliances & External Research , Santen Incorporated, Emeryville, California.,2 Department of Pharmaceutical Sciences, Texas Southern University , Houston, Texas.,3 Department of Pharmacology and Neuroscience, University of North Texas Health Sciences Center , Fort Worth, Texas
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Marangoz D, Guzel E, Eyuboglu S, Gumusel A, Seckin I, Ciftci F, Yilmaz B, Yalvac I. Comparison of the neuroprotective effects of brimonidine tartrate and melatonin on retinal ganglion cells. Int Ophthalmol 2017; 38:2553-2562. [PMID: 29159432 DOI: 10.1007/s10792-017-0768-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Accepted: 11/12/2017] [Indexed: 02/07/2023]
Abstract
PURPOSE We aimed to compare the neuroprotective effects of brimonidine tartrate (BRT) and melatonin (MEL) on retinal ganglion cells (RGCs) in a rat glaucoma model. METHODS Thirty-six adult Wistar albino rats were allocated into six groups: control (C), glaucoma (G), BRT, MEL, G + BRT and G + MEL. After establishing the glaucoma model, intraocular pressure (IOP) of all animals measured at day 4 and day 30 was compared statistically with day 0 and day 4, respectively. Prior to sacrification at day 30 for histological evaluation and TUNEL analysis, retrograde labeling of non-apoptotic RGCs with 3% Fluorogold was performed and RGCs were evaluated under fluorescein microscope. RESULTS IOP measurements at day 4 were significantly higher than basal measurements in all glaucoma groups. BRT alone induced a time-dependent decrease in IOP (p < 0.05), while MEL alone failed to reduce IOP. However, both BRT and MEL reduced IOP in the presence of glaucoma at day 30 (p < 0.05). BRT treatment significantly reversed the reduced non-apoptotic RGC counts (p < 0.01) and increased TUNEL-positive RGCs (p < 0.001) to control group levels in the presence of glaucoma. However, no statistical significance was found between groups G and G + MEL considering 3% Fluorogold-labeled cell counts and apoptotic index values. CONCLUSION Our study revealed that systemic administration of BRT also has an IOP reducing effect. MEL has no neuroprotective effect on RGCs; on the other hand, BRT acts as a neuroprotective agent against glaucomatous injury, when applied systemically.
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Affiliation(s)
- Deniz Marangoz
- Department of Ophthalmology, Faculty of Medicine, Yeditepe University, Sakir Kesebir cad. Gazi Umur Pasa sok. No: 28, 34349, Beşiktaş-Istanbul, Turkey.
| | - Elif Guzel
- Department of Histology and Embryology, Cerrahpasa Faculty of Medicine, Istanbul University, Kocamustafapasa cad., 34098, Fatih-Istanbul, Turkey.
| | - Signem Eyuboglu
- Department of Physiology, Faculty of Medicine, Yeditepe University, Inonu mah. Kayisdagi cad. 26 Agustos Yerleskesi, 34755, Istanbul, Turkey
| | - Asli Gumusel
- Department of Histology and Embryology, Cerrahpasa Faculty of Medicine, Istanbul University, Kocamustafapasa cad., 34098, Fatih-Istanbul, Turkey
| | - Ismail Seckin
- Department of Histology and Embryology, Cerrahpasa Faculty of Medicine, Istanbul University, Kocamustafapasa cad., 34098, Fatih-Istanbul, Turkey
| | - Ferda Ciftci
- Department of Ophthalmology, Faculty of Medicine, Yeditepe University, Sakir Kesebir cad. Gazi Umur Pasa sok. No: 28, 34349, Beşiktaş-Istanbul, Turkey
| | - Bayram Yilmaz
- Department of Physiology, Faculty of Medicine, Yeditepe University, Inonu mah. Kayisdagi cad. 26 Agustos Yerleskesi, 34755, Istanbul, Turkey
| | - Ilgaz Yalvac
- Department of Ophthalmology, Faculty of Medicine, Yeditepe University, Sakir Kesebir cad. Gazi Umur Pasa sok. No: 28, 34349, Beşiktaş-Istanbul, Turkey
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Neuroprotection in Glaucoma: Old and New Promising Treatments. Adv Pharmacol Sci 2017; 2017:4320408. [PMID: 30723498 PMCID: PMC5664381 DOI: 10.1155/2017/4320408] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 09/02/2017] [Accepted: 09/13/2017] [Indexed: 12/21/2022] Open
Abstract
Glaucoma is a major global cause of blindness, but the molecular mechanisms responsible for the neurodegenerative damage are not clear. Undoubtedly, the high intraocular pressure (IOP) and the secondary ischemic and mechanical damage of the optic nerve have a crucial role in retinal ganglion cell (RGC) death. Several studies specifically analyzed the events that lead to nerve fiber layer thinning, showing the importance of both intra- and extracellular factors. In parallel, many neuroprotective substances have been tested for their efficacy and safety in hindering the negative effects that lead to RGC death. New formulations of these compounds, also suitable for chronic oral administration, are likely to be used in clinical practice in the future along with conventional therapies, in order to control the progression of the visual impairment due to primary open-angle glaucoma (POAG). This review illustrates some of these old and new promising agents for the adjuvant treatment of POAG, with particular emphasis on forskolin and melatonin.
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20
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Crooke A, Huete-Toral F, Colligris B, Pintor J. The role and therapeutic potential of melatonin in age-related ocular diseases. J Pineal Res 2017; 63. [PMID: 28658514 DOI: 10.1111/jpi.12430] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 06/23/2017] [Indexed: 12/20/2022]
Abstract
The eye is continuously exposed to solar UV radiation and pollutants, making it prone to oxidative attacks. In fact, oxidative damage is a major cause of age-related ocular diseases including cataract, glaucoma, age-related macular degeneration, and diabetic retinopathy. As the nature of lens cells, trabecular meshwork cells, retinal ganglion cells, retinal pigment epithelial cells, and photoreceptors is postmitotic, autophagy plays a critical role in their cellular homeostasis. In age-related ocular diseases, this process is impaired, and thus, oxidative damage becomes irreversible. Other conditions such as low-grade chronic inflammation and angiogenesis also contribute to the development of retinal diseases (glaucoma, age-related macular degeneration and diabetic retinopathy). As melatonin is known to have remarkable qualities such as antioxidant/antinitridergic, mitochondrial protector, autophagy modulator, anti-inflammatory, and anti-angiogenic, it can represent a powerful tool to counteract all these diseases. The present review analyzes the role and therapeutic potential of melatonin in age-related ocular diseases, focusing on nitro-oxidative stress, autophagy, inflammation, and angiogenesis mechanisms.
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Affiliation(s)
- Almudena Crooke
- Department of Biochemistry and Molecular Biology IV, Group Ocupharm, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Madrid, Spain
| | - Fernando Huete-Toral
- Department of Biochemistry and Molecular Biology IV, Group Ocupharm, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Madrid, Spain
| | - Basilio Colligris
- Department of Biochemistry and Molecular Biology IV, Group Ocupharm, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Madrid, Spain
| | - Jesús Pintor
- Department of Biochemistry and Molecular Biology IV, Group Ocupharm, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Madrid, Spain
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21
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Martinez-Aguila A, Fonseca B, Perez de Lara MJ, Pintor J. Effect of Melatonin and 5-Methoxycarbonylamino-N-Acetyltryptamine on the Intraocular Pressure of Normal and Glaucomatous Mice. ACTA ACUST UNITED AC 2016; 357:293-9. [DOI: 10.1124/jpet.115.231456] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 03/02/2016] [Indexed: 01/02/2023]
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Pescosolido N, Gatto V, Stefanucci A, Rusciano D. Oral treatment with the melatonin agonist agomelatine lowers the intraocular pressure of glaucoma patients. Ophthalmic Physiol Opt 2015; 35:201-5. [DOI: 10.1111/opo.12189] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2014] [Accepted: 11/29/2014] [Indexed: 01/21/2023]
Affiliation(s)
- Nicola Pescosolido
- Facoltà di Medicina e Odontoiatria; Università di Roma La Sapienza; Rome Italy
| | - Vittorio Gatto
- Facoltà di Medicina e Odontoiatria; Università di Roma La Sapienza; Rome Italy
| | - Alessio Stefanucci
- Facoltà di Medicina e Odontoiatria; Università di Roma La Sapienza; Rome Italy
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Loma P, Guzman-Aranguez A, Pérez de Lara MJ, Pintor J. Diadenosine tetraphosphate induces tight junction disassembly thus increasing corneal epithelial permeability. Br J Pharmacol 2014; 172:1045-58. [PMID: 25297531 DOI: 10.1111/bph.12972] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 09/26/2014] [Accepted: 09/29/2014] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND AND PURPOSE Here, we have studied the effects of the dinucleotide P(1), P(4)-Di (adenosine-5') tetraphosphate (Ap4 A) on corneal barrier function conferred by the tight junction (TJ) proteins and its possible involvement in ocular drug delivery and therapeutic efficiency. EXPERIMENTAL APPROACH Experiments in vitro were performed using human corneal epithelial cells (HCLEs) treated with Ap4 A (100 μM) for 5 min. Western blot analysis and transepithelial electrical resistance (TEER) were performed to study the TJ protein levels and barrier function respectively. Intracellular pathways involved were determined using an ERK inhibitor and P2Y(2) receptor siRNAs. In in vivo assays with New Zealand rabbits, TJ integrity was examined by zonula occludens-1 (ZO-1) staining. The hypotensive compound 5-methoxycarbonylamino-N-acetyltryptamine (5-MCA-NAT) was used to assess improved delivery, measuring its levels by HPLC and measuring intraocular pressure using 5-MCA-NAT, P2Y receptor antagonists and P2Y2 siRNAs. KEY RESULTS Two hours after Ap4 A pretreatment, TJ protein levels in HCLE cells were reduced around 40% compared with control. TEER values were significantly reduced at 2 and 4 h (68 and 52% respectively). TJ reduction and ERK activation were blocked by the ERK inhibitor U012 and P2Y(2) siRNAs. In vivo, topical application of Ap4 A disrupted ZO-1 membrane distribution. 5-MCA-NAT levels in the aqueous humour were higher when Ap4 A was previously instilled and its hypotensive effect was also increased. This action was reversed by P2Y receptor antagonists and P2Y(2) siRNA. CONCLUSIONS AND IMPLICATIONS Ap4 A increased corneal epithelial barrier permeability. Its application could improve ocular drug delivery and consequently therapeutic efficiency.
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Affiliation(s)
- P Loma
- Department of Biochemistry and Molecular Biology IV, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Spain
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Alkozi HA, Pintor J. Melatonin and derivatives as promising tools for glaucoma treatment. World J Ophthalmol 2013; 3:32-37. [DOI: 10.5318/wjo.v3.i4.32] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 11/13/2013] [Indexed: 02/06/2023] Open
Abstract
Neurohormones melatonin and its analogues are present with an important physiological and pharmacological ability to reduce intraocular pressure (IOP); thus, they are suitable for the treatment of ocular hypertension often associated with glaucoma. It is demonstrated that two of its analogues, 5-MCA-NAT and IIK7, are more effective than melatonin to reduce IOP for a longer period of time. The research for the discovery of better compounds resulted in the development of newer and improved analogues compared to 5-MCA-NAT and IIK7. Furthermore, already commercially available drugs currently used as treatment for other pathologies, presenting a resemblance to the melatonin structure, are being tested as potential glaucoma drugs. In this sense, agomelatine, which is already used as an anti-depressant medicine, is recognized as a worthy candidate since it reduces IOP, even under hypertensive conditions. To sum up, the use of melatonin and its analogues as promising anti-glaucomatous substances is of great importance and should be given serious consideration.
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Li Z, Ding YS, Gifford A, Fowler JS, Gatley JS. Synthesis of structurally identical fluorine-18 and iodine isotope labeling compounds for comparative imaging. Bioconjug Chem 2003; 14:287-94. [PMID: 12643738 DOI: 10.1021/bc025616n] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis of a benzophenone-based labeling compound designed for comparative imaging studies with both in vivo positron emission tomograph (PET) and single-photon computed tomography (SPECT) and ex vivo autoradiography is described. The new compound can be labeled with either F-18 or iodine radioisotopes to give two different radioisotopmers: N-[2-fluoro-5-(3-[I-131]iodobenzoyl)benzyl]-2-bromoacetamide (1) and N-[2-[F-18]fluoro-5-(3-iodobenzoyl)benzyl]-2-bromoacetamide (2). Compound 1 and 2 have a 2-bromoacetyl group, which can be used to conjugate with biomolecules through a nucleophilic substitution reaction. Compound 1 was synthesized from the corresponding tributyltin derivatives via an oxidative destannylation reaction, and compound 2 was prepared via a four-step radiosynthesis (nucleophilic aromatic substitution, reduction, oxidation, and alkylation) starting from 4-(N,N,N-trimethylammonio)-3-cyano-3'-iodobenzophenone triflate. A remarkably high radiochemical yield (>90%) was achieved for the F-18 nucleophilic aromatic substitution under mild conditions (room temperature in less than 10 min), indicating the structural advantage of the designed molecule to facilitate the F-18 for trimethylammonium substitution in the presence of two electron-withdrawing groups (nitrile and carbonyl). The overall radiosynthesis time for compound 2 is less than 3 h after end of bombardment (EOB) with an unoptimized radiochemical yield of about 2% (not decay corrected) and specific activity of 0.8 Ci/micromol at EOB. The radiolabeling precursors for compound 1 and 2 were synthesized via a carbon-carbon bond-forming reaction between 2-substituted-5-lithiobenzonitrile and 3-substituted benzaldehyde derivatives. Compounds 1 and 2 should allow us to label biomolecules with F-18 or iodine isotopes and gives structurally identical products, which are expected to have identical biological properties and should be useful for comparative imaging studies.
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Affiliation(s)
- Zizhong Li
- Medical Department and Chemistry Department, Brookhaven National Laboratory, Upton, New York 11978, USA.
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