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Zheng J, Zhang W, Xu R, Liu L. The role of adiponectin and its receptor signaling in ocular inflammation-associated diseases. Biochem Biophys Res Commun 2024; 717:150041. [PMID: 38710142 DOI: 10.1016/j.bbrc.2024.150041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 04/13/2024] [Accepted: 04/29/2024] [Indexed: 05/08/2024]
Abstract
Ocular inflammation-associated diseases are leading causes of global visual impairment, with limited treatment options. Adiponectin, a hormone primarily secreted by adipose tissue, binds to its receptors, which are widely distributed throughout the body, exerting powerful physiological regulatory effects. The protective role of adiponectin in various inflammatory diseases has gained increasing attention in recent years. Previous studies have confirmed the presence of adiponectin and its receptors in the eyes. Furthermore, adiponectin and its analogs have shown potential as novel drugs for the treatment of inflammatory eye diseases. This article summarizes the evidence for the interplay between adiponectin and inflammatory eye diseases and provides new perspectives on the diagnostic and therapeutic possibilities of adiponectin.
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Affiliation(s)
- Jing Zheng
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China; Department of Optometry and Visual Science, West China Hospital, Sichuan University, Chengdu, China
| | - Wenqiu Zhang
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China; Department of Optometry and Visual Science, West China Hospital, Sichuan University, Chengdu, China
| | - Ran Xu
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China; Department of Optometry and Visual Science, West China Hospital, Sichuan University, Chengdu, China
| | - Longqian Liu
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China; Department of Optometry and Visual Science, West China Hospital, Sichuan University, Chengdu, China.
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2
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Bejarano E, Domenech-Bendaña A, Avila-Portillo N, Rowan S, Edirisinghe S, Taylor A. Glycative stress as a cause of macular degeneration. Prog Retin Eye Res 2024:101260. [PMID: 38521386 DOI: 10.1016/j.preteyeres.2024.101260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 03/08/2024] [Accepted: 03/11/2024] [Indexed: 03/25/2024]
Abstract
People are living longer and rates of age-related diseases such as age-related macular degeneration (AMD) are accelerating, placing enormous burdens on patients and health care systems. The quality of carbohydrate foods consumed by an individual impacts health. The glycemic index (GI) is a kinetic measure of the rate at which glucose arrives in the blood stream after consuming various carbohydrates. Consuming diets that favor slowly digested carbohydrates releases sugar into the bloodstream gradually after consuming a meal (low glycemic index). This is associated with reduced risk for major age-related diseases including AMD, cardiovascular disease, and diabetes. In comparison, consuming the same amounts of different carbohydrates in higher GI diets, releases glucose into the blood rapidly, causing glycative stress as well as accumulation of advanced glycation end products (AGEs). Such AGEs are cytotoxic by virtue of their forming abnormal proteins and protein aggregates, as well as inhibiting proteolytic and other protective pathways that might otherwise selectively recognize and remove toxic species. Using in vitro and animal models of glycative stress, we observed that consuming higher GI diets perturbs metabolism and the microbiome, resulting in a shift to more lipid-rich metabolomic profiles. Interactions between aging, diet, eye phenotypes and physiology were observed. A large body of laboratory animal and human clinical epidemiologic data indicates that consuming lower GI diets, or lower glycemia diets, is protective against features of early AMD (AMDf) in mice and AMD prevalence or AMD progression in humans. Drugs may be optimised to diminish the ravages of higher glycemic diets. Human trials are indicated to determine if AMD progression can be retarded using lower GI diets. Here we summarized the current knowledge regarding the pathological role of glycative stress in retinal dysfunction and how dietary strategies might diminish retinal disease.
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Affiliation(s)
- Eloy Bejarano
- Department of Biomedical Sciences, School of Health Sciences and Veterinary School, Universidad Cardenal Herrera-CEU, CEU Universities, Valencia, Spain
| | - Alicia Domenech-Bendaña
- Department of Biomedical Sciences, School of Health Sciences and Veterinary School, Universidad Cardenal Herrera-CEU, CEU Universities, Valencia, Spain
| | | | - Sheldon Rowan
- Tufts University Human Nutrition Research Center on Aging, United States
| | - Sachini Edirisinghe
- Tufts University Friedman School of Nutrition Science and Policy, United States
| | - Allen Taylor
- Tufts University Friedman School of Nutrition Science and Policy, United States.
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Jahagirdar D, Yadav S, Gore M, Korpale V, Mathpati CS, Chidambaram S, Majumder A, Jain R, Dandekar P. Compartmentalized microfluidic device for in vitro co‐culture of retinal cells. Biotechnol J 2022; 17:e2100530. [DOI: 10.1002/biot.202100530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 06/01/2022] [Accepted: 06/01/2022] [Indexed: 11/10/2022]
Affiliation(s)
- Devashree Jahagirdar
- Department of Pharmaceutical Sciences and Technology Institute of Chemical Technology Mumbai 400019 India
| | - Shital Yadav
- Department of Chemical Engineering Indian Institute of Technology Mumbai 400076 India
| | - Manish Gore
- Department of Pharmaceutical Sciences and Technology Institute of Chemical Technology Mumbai 400019 India
| | - Vikram Korpale
- Department of Chemical Engineering Institute of Chemical Technology Mumbai 400019 India
| | - C S Mathpati
- Department of Chemical Engineering Institute of Chemical Technology Mumbai 400019 India
| | - Subbulakshmi Chidambaram
- Dept. of Biochemistry and Molecular Biology Pondicherry Central University Puducherry 605014 India
| | - Abhijit Majumder
- Department of Chemical Engineering Indian Institute of Technology Mumbai 400076 India
| | - Ratnesh Jain
- Department of Chemical Engineering Institute of Chemical Technology Mumbai 400019 India
| | - Prajakta Dandekar
- Department of Pharmaceutical Sciences and Technology Institute of Chemical Technology Mumbai 400019 India
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Goit RK, Taylor AW, Lo ACY. Anti-inflammatory α-Melanocyte-Stimulating Hormone Protects Retina After Ischemia/Reperfusion Injury in Type I Diabetes. Front Neurosci 2022; 16:799739. [PMID: 35281489 PMCID: PMC8914517 DOI: 10.3389/fnins.2022.799739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 01/19/2022] [Indexed: 11/13/2022] Open
Abstract
Retinal ischemia/reperfusion (I/R) injury is a major cause of vision loss in many ocular diseases. Retinal I/R injury is common in diabetic retinopathy, which as a result of hyperglycemia damages the retina and can cause blindness if left untreated. Inflammation is a major contributing factor in the pathogenesis of I/R injury. α-Melanocyte-stimulating hormone (α-MSH) is an anti-inflammatory peptide hormone that has displayed protective effects against I/R-induced organ damages. Here, we aimed to investigate the protective role of α-MSH on I/R-induced diabetic retinal damage using hyperglycemic C57BL/6J Ins2Akita/+ mice. Experimental I/R injury was induced by blocking the right middle cerebral artery (MCA) for 2 h followed by 2 h or 22 h of reperfusion using the intraluminal method. Since ophthalmic artery originates proximal to the origin of the MCA, the filament also blocked blood supply to the retina. Upon treatment with α-MSH at 1 h after ischemia and 1 h after reperfusion, animals displayed significant improvement in amplitudes of b-wave and oscillatory potentials during electroretinography. α-MSH also prevented I/R-induced histological alterations and inhibited the development of retinal swelling. Loss of retinal ganglion cells as well as oxidative stress were significantly attenuated in the α-MSH-treated retinae. Level of interleukin 10 was significantly increased after α-MSH treatment. Moreover, gene expression of glutamate aspartate transporter 1, monocarboxylate transporter (MCT) 1 and MCT-2 were significantly higher after α-MSH administration. In conclusion, α-MSH mitigates the severity of I/R-induced retinal damage under hyperglycemic condition. These beneficial effects of α-MSH may have important therapeutic implications against retinal I/R injury under hyperglycemic condition.
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Affiliation(s)
- Rajesh Kumar Goit
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Andrew W. Taylor
- Department of Ophthalmology, Boston University School of Medicine, Boston, MA, United States
| | - Amy C. Y. Lo
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
- *Correspondence: Amy C. Y. Lo, , orcid.org/0000-0003-4239-6851
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Pitale PM, Saltykova IV, Adu-Agyeiwaah Y, Li Calzi S, Satoh T, Akira S, Gorbatyuk O, Boulton ME, Pardue MT, Garvey WT, Athar M, Grant MB, Gorbatyuk MS. Tribbles Homolog 3 Mediates the Development and Progression of Diabetic Retinopathy. Diabetes 2021; 70:1738-1753. [PMID: 33975909 PMCID: PMC8385618 DOI: 10.2337/db20-1268] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 05/04/2021] [Indexed: 11/21/2022]
Abstract
The current understanding of the molecular pathogenesis of diabetic retinopathy does not provide a mechanistic link between early molecular changes and the subsequent progression of the disease. In this study, we found that human diabetic retinas overexpressed TRIB3 and investigated the role of TRIB3 in diabetic retinal pathobiology in mice. We discovered that TRIB3 controlled major molecular events in early diabetic retinas via HIF1α-mediated regulation of retinal glucose flux, reprogramming cellular metabolism, and governing of inflammatory gene expression. These early molecular events further defined the development of neurovascular deficit observed in mice with diabetic retinopathy. TRIB3 ablation in the streptozotocin-induced mouse model led to significant retinal ganglion cell survival and functional restoration accompanied by a dramatic reduction in pericyte loss and acellular capillary formation. Under hypoxic conditions, TRIB3 contributed to advanced proliferative stages by significant upregulation of GFAP and VEGF expression, thus controlling gliosis and aberrant vascularization in oxygen-induced retinopathy mouse retinas. Overall, our data reveal that TRIB3 is a master regulator of diabetic retinal pathophysiology that may accelerate the onset and progression of diabetic retinopathy to proliferative stages in humans and present TRIB3 as a potentially novel therapeutic target for diabetic retinopathy.
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Affiliation(s)
- Priyamvada M Pitale
- Department of Optometry and Vision Science, School of Optometry, University of Alabama at Birmingham, Birmingham, AL
| | - Irina V Saltykova
- Department of Optometry and Vision Science, School of Optometry, University of Alabama at Birmingham, Birmingham, AL
| | - Yvonne Adu-Agyeiwaah
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL
| | - Sergio Li Calzi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL
| | - Takashi Satoh
- Department of Immune Regulation, Tokyo Medical and Dental University, Tokyo, Japan
| | - Shizuo Akira
- WPI Immunology Frontier Research Center, Osaka University, Osaka, Japan
| | - Oleg Gorbatyuk
- Department of Optometry and Vision Science, School of Optometry, University of Alabama at Birmingham, Birmingham, AL
| | - Michael E Boulton
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL
| | - Machelle T Pardue
- Department of Biomedical Engineering, Georgia Institute of Technology, and Atlanta VA Center of Excellence for Visual and Neurocognitive Rehabilitation
| | - W Timothy Garvey
- Department of Nutrition Sciences and Department of Dermatology, University of Alabama at Birmingham, Birmingham, AL
| | - Mohammad Athar
- School of Medicine, University of Alabama at Birmingham, Birmingham, AL
| | - Maria B Grant
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL
| | - Marina S Gorbatyuk
- Department of Optometry and Vision Science, School of Optometry, University of Alabama at Birmingham, Birmingham, AL
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Bodnar CN, Watson JB, Higgins EK, Quan N, Bachstetter AD. Inflammatory Regulation of CNS Barriers After Traumatic Brain Injury: A Tale Directed by Interleukin-1. Front Immunol 2021; 12:688254. [PMID: 34093593 PMCID: PMC8176952 DOI: 10.3389/fimmu.2021.688254] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 05/05/2021] [Indexed: 01/13/2023] Open
Abstract
Several barriers separate the central nervous system (CNS) from the rest of the body. These barriers are essential for regulating the movement of fluid, ions, molecules, and immune cells into and out of the brain parenchyma. Each CNS barrier is unique and highly dynamic. Endothelial cells, epithelial cells, pericytes, astrocytes, and other cellular constituents each have intricate functions that are essential to sustain the brain's health. Along with damaging neurons, a traumatic brain injury (TBI) also directly insults the CNS barrier-forming cells. Disruption to the barriers first occurs by physical damage to the cells, called the primary injury. Subsequently, during the secondary injury cascade, a further array of molecular and biochemical changes occurs at the barriers. These changes are focused on rebuilding and remodeling, as well as movement of immune cells and waste into and out of the brain. Secondary injury cascades further damage the CNS barriers. Inflammation is central to healthy remodeling of CNS barriers. However, inflammation, as a secondary pathology, also plays a role in the chronic disruption of the barriers' functions after TBI. The goal of this paper is to review the different barriers of the brain, including (1) the blood-brain barrier, (2) the blood-cerebrospinal fluid barrier, (3) the meningeal barrier, (4) the blood-retina barrier, and (5) the brain-lesion border. We then detail the changes at these barriers due to both primary and secondary injury following TBI and indicate areas open for future research and discoveries. Finally, we describe the unique function of the pro-inflammatory cytokine interleukin-1 as a central actor in the inflammatory regulation of CNS barrier function and dysfunction after a TBI.
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Affiliation(s)
- Colleen N. Bodnar
- Department of Neuroscience, University of Kentucky, Lexington, KY, United States
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY, United States
| | - James B. Watson
- Department of Neuroscience, University of Kentucky, Lexington, KY, United States
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY, United States
| | - Emma K. Higgins
- Department of Neuroscience, University of Kentucky, Lexington, KY, United States
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY, United States
| | - Ning Quan
- Department of Biomedical Science, Charles E. Schmidt College of Medicine and Brain Institute, Florida Atlantic University, Jupiter, FL, United States
| | - Adam D. Bachstetter
- Department of Neuroscience, University of Kentucky, Lexington, KY, United States
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY, United States
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7
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Aragonès G, Rowan S, G Francisco S, Yang W, Weinberg J, Taylor A, Bejarano E. Glyoxalase System as a Therapeutic Target against Diabetic Retinopathy. Antioxidants (Basel) 2020; 9:antiox9111062. [PMID: 33143048 PMCID: PMC7692619 DOI: 10.3390/antiox9111062] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/25/2020] [Accepted: 10/27/2020] [Indexed: 12/14/2022] Open
Abstract
Hyperglycemia, a defining characteristic of diabetes, combined with oxidative stress, results in the formation of advanced glycation end products (AGEs). AGEs are toxic compounds that have adverse effects on many tissues including the retina and lens. AGEs promote the formation of reactive oxygen species (ROS), which, in turn, boost the production of AGEs, resulting in positive feedback loops, a vicious cycle that compromises tissue fitness. Oxidative stress and the accumulation of AGEs are etiologically associated with the pathogenesis of multiple diseases including diabetic retinopathy (DR). DR is a devastating microvascular complication of diabetes mellitus and the leading cause of blindness in working-age adults. The onset and development of DR is multifactorial. Lowering AGEs accumulation may represent a potential therapeutic approach to slow this sight-threatening diabetic complication. To set DR in a physiological context, in this review we first describe relations between oxidative stress, formation of AGEs, and aging in several tissues of the eye, each of which is associated with a major age-related eye pathology. We summarize mechanisms of AGEs generation and anti-AGEs detoxifying systems. We specifically feature the potential of the glyoxalase system in the retina in the prevention of AGEs-associated damage linked to DR. We provide a comparative analysis of glyoxalase activity in different tissues from wild-type mice, supporting a major role for the glyoxalase system in the detoxification of AGEs in the retina, and present the manipulation of this system as a therapeutic strategy to prevent the onset of DR.
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Affiliation(s)
- Gemma Aragonès
- Laboratory for Nutrition and Vision Research, USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02155, USA; (G.A.); (S.R.); (S.G.F.); (W.Y.); (J.W.)
| | - Sheldon Rowan
- Laboratory for Nutrition and Vision Research, USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02155, USA; (G.A.); (S.R.); (S.G.F.); (W.Y.); (J.W.)
- Department of Ophthalmology, Tufts University School of Medicine, Boston, MA 02155, USA
- Friedman School of Nutrition and Science Policy, Tufts University, Boston, MA 02155, USA
| | - Sarah G Francisco
- Laboratory for Nutrition and Vision Research, USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02155, USA; (G.A.); (S.R.); (S.G.F.); (W.Y.); (J.W.)
| | - Wenxin Yang
- Laboratory for Nutrition and Vision Research, USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02155, USA; (G.A.); (S.R.); (S.G.F.); (W.Y.); (J.W.)
| | - Jasper Weinberg
- Laboratory for Nutrition and Vision Research, USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02155, USA; (G.A.); (S.R.); (S.G.F.); (W.Y.); (J.W.)
| | - Allen Taylor
- Laboratory for Nutrition and Vision Research, USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02155, USA; (G.A.); (S.R.); (S.G.F.); (W.Y.); (J.W.)
- Department of Ophthalmology, Tufts University School of Medicine, Boston, MA 02155, USA
- Friedman School of Nutrition and Science Policy, Tufts University, Boston, MA 02155, USA
- Correspondence: (A.T.); (E.B.); Tel.: +617-556-3156 (A.T.)
| | - Eloy Bejarano
- Laboratory for Nutrition and Vision Research, USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02155, USA; (G.A.); (S.R.); (S.G.F.); (W.Y.); (J.W.)
- Universidad Cardenal Herrera-CEU, CEU Universities, 46115 Valencia, Spain
- Correspondence: (A.T.); (E.B.); Tel.: +617-556-3156 (A.T.)
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Francisco SG, Smith KM, Aragonès G, Whitcomb EA, Weinberg J, Wang X, Bejarano E, Taylor A, Rowan S. Dietary Patterns, Carbohydrates, and Age-Related Eye Diseases. Nutrients 2020; 12:E2862. [PMID: 32962100 DOI: 10.3390/nu12092862] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 09/16/2020] [Accepted: 09/16/2020] [Indexed: 12/19/2022] Open
Abstract
Over a third of older adults in the U.S. experience significant vision loss, which decreases independence and is a biomarker of decreased health span. As the global aging population is expanding, it is imperative to uncover strategies to increase health span and reduce the economic burden of this age-related disease. While there are some treatments available for age-related vision loss, such as surgical removal of cataracts, many causes of vision loss, such as dry age-related macular degeneration (AMD), remain poorly understood and no treatments are currently available. Therefore, it is necessary to better understand the factors that contribute to disease progression for age-related vision loss and to uncover methods for disease prevention. One such factor is the effect of diet on ocular diseases. There are many reviews regarding micronutrients and their effect on eye health. Here, we discuss the impact of dietary patterns on the incidence and progression of age-related eye diseases, namely AMD, cataracts, diabetic retinopathy, and glaucoma. Then, we focus on the specific role of dietary carbohydrates, first by outlining the physiological effects of carbohydrates on the body and then how these changes translate into eye and age-related ocular diseases. Finally, we discuss future directions of nutrition research as it relates to aging and vision loss, with a discussion of caloric restriction, intermittent fasting, drug interventions, and emerging randomized clinical trials. This is a rich field with the capacity to improve life quality for millions of people so they may live with clear vision for longer and avoid the high cost of vision-saving surgeries.
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Abstract
Energy demand of neurons in brain that is covered by glucose supply from the blood is ensured by glucose transporters in capillaries and brain cells. In brain, the facilitative diffusion glucose transporters GLUT1-6 and GLUT8, and the Na+-d-glucose cotransporters SGLT1 are expressed. The glucose transporters mediate uptake of d-glucose across the blood-brain barrier and delivery of d-glucose to astrocytes and neurons. They are critically involved in regulatory adaptations to varying energy demands in response to differing neuronal activities and glucose supply. In this review, a comprehensive overview about verified and proposed roles of cerebral glucose transporters during health and diseases is presented. Our current knowledge is mainly based on experiments performed in rodents. First, the functional properties of human glucose transporters expressed in brain and their cerebral locations are described. Thereafter, proposed physiological functions of GLUT1, GLUT2, GLUT3, GLUT4, and SGLT1 for energy supply to neurons, glucose sensing, central regulation of glucohomeostasis, and feeding behavior are compiled, and their roles in learning and memory formation are discussed. In addition, diseases are described in which functional changes of cerebral glucose transporters are relevant. These are GLUT1 deficiency syndrome (GLUT1-SD), diabetes mellitus, Alzheimer’s disease (AD), stroke, and traumatic brain injury (TBI). GLUT1-SD is caused by defect mutations in GLUT1. Diabetes and AD are associated with changed expression of glucose transporters in brain, and transporter-related energy deficiency of neurons may contribute to pathogenesis of AD. Stroke and TBI are associated with changes of glucose transporter expression that influence clinical outcome.
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Abstract
Blood-retinal barrier (BRB) includes inner BRB (iBRB) and outer BRB (oBRB), which are formed by retinal capillary endothelial (RCEC) cells and by retinal pigment epithelial (RPE) cells in collaboration with Bruch's membrane and the choriocapillaris, respectively. Functions of the BRB are to regulate fluids and molecular movement between the ocular vascular beds and retinal tissues and to prevent leakage of macromolecules and other potentially harmful agents into the retina, keeping the microenvironment of the retina and retinal neurons. These functions are mainly attributed to absent fenestrations of RCECs, tight junctions, expression of a great diversity of transporters, and coverage of pericytes and glial cells. BRB existence also becomes a reason that systemic administration for some drugs is not suitable for the treatment of retinal diseases. Some diseases (such as diabetes and ischemia-reperfusion) impair BRB function via altering tight junctions, RCEC death, and transporter expression. This chapter will illustrate function of BRB, expressions and functions of these transporters, and their clinical significances.
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Affiliation(s)
- Xiaodong Liu
- grid.254147.10000 0000 9776 7793School of Pharmacy, China Pharmaceutical University, Nanjing, Jiangsu China
| | - Guoyu Pan
- grid.9227.e0000000119573309Shanghai Institute of Materia Medica, Chinese Academy of Science, Shanghai, Shanghai China
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11
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Country MW. Retinal metabolism: A comparative look at energetics in the retina. Brain Res 2017; 1672:50-7. [DOI: 10.1016/j.brainres.2017.07.025] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 07/25/2017] [Accepted: 07/26/2017] [Indexed: 12/27/2022]
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12
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Soltésová D, Veselá A, Mravec B, Herichová I. Daily profile of glut1 and glut4 expression in tissues inside and outside the blood-brain barrier in control and streptozotocin-treated rats. Physiol Res 2014; 62:S115-24. [PMID: 24329691 DOI: 10.33549/physiolres.932596] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Glucose is molecule usually studied in relation to metabolism. Except for this traditional view, it is known that under certain conditions glucose can serve as a signal molecule for the circadian system. The circadian system is entrained by relevant synchronizing cues that can be tissue-dependent. Central oscillator is synchronized mainly by light-dark cycle, while peripheral oscillators can be entrained by food intake. Glucose transport in the organism is controlled by insulin dependent and independent mechanism. Therefore, we employed streptozotocin-induced diabetes to elucidate the influence of metabolic changes on glucose transporter (glut1, glut4) 24-h expression profile in peripheral oscillators in tissues, inside (frontal cortex, cerebellum) and outside (heart) the blood-brain barrier. Diabetes was induced by streptozotocin injection. Seventeen days later, sampling was performed during a 24-h cycle. Gene expression was measured using real-time PCR. We observed down-regulation of glut1 and glut4 expression in the heart of diabetic rats. The expression of glut1 and glut4 in brain areas was not down-regulated, however, we observed trend to phase advance in glut1 expression in the cerebellum. These results may indicate higher glucose levels in diabetic brain, which might influence regulation of clock gene expression in different manner in brain compared to periphery.
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Affiliation(s)
- D Soltésová
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovak Republic.
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Lind KR, Ball KK, Cruz NF, Dienel GA. The unfolded protein response to endoplasmic reticulum stress in cultured astrocytes and rat brain during experimental diabetes. Neurochem Int 2013; 62:784-95. [PMID: 23411409 DOI: 10.1016/j.neuint.2013.02.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Revised: 01/29/2013] [Accepted: 02/04/2013] [Indexed: 12/21/2022]
Abstract
Oxidative-nitrosative stress and inflammatory responses are associated with endoplasmic reticulum (ER) stress in diabetic retinopathy, raising the possibility that disturbances in ER protein processing may contribute to CNS dysfunction in diabetics. Upregulation of the unfolded protein response (UPR) is a homeostatic response to accumulation of abnormal proteins in the ER, and the present study tested the hypothesis that the UPR is upregulated in two models for diabetes, cultured astrocytes grown in 25mmol/L glucose for up to 4weeks and brain of streptozotocin (STZ)-treated rats with diabetes for 1-7months. Markers associated with translational blockade (phospho-eIF2α and apoptosis (CHOP), inflammatory response (inducible nitric oxide synthase, iNOS), and nitrosative stress (nuclear translocation of glyceraldehyde-3-phosphate dehydrogenase, GAPDH) were not detected in either model. Nrf2 was present in nuclei of low- and high-glucose cultures, consistent with oxidative stress. Astrocytic ATF4 expression was not altered by culture glucose concentration, whereas phospho-IRE and ATF6 levels were higher in low- compared with high-glucose cultures. The glucose-regulated chaperones, GRP78 and GRP94, were also expressed at higher levels in low- than high-glucose cultures, probably due to recurrent glucose depletion between feeding cycles. In STZ-rat cerebral cortex, ATF4 level was transiently reduced at 4months, and p-IRE levels were transiently elevated at 3months. However, GRP78 and GRP94 expression was not upregulated, and iNOS, amyloid-β, and nuclear accumulation of GAPDH were not evident in STZ-diabetic brain. High-glucose cultured astrocytes and STZ-diabetic brain are relatively resistant to diabetes-induced ER stress, in sharp contrast with cultured retinal Müller cells and diabetic rodent retina.
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Abstract
The occurrence of altered brain glucose metabolism has long been suggested in both diabetes and Alzheimer’s diseases. However, the preceding mechanism to altered glucose metabolism has not been well understood. Glucose enters the brain via glucose transporters primarily present at the blood-brain barrier. Any changes in glucose transporter function and expression dramatically affects brain glucose homeostasis and function. In the brains of both diabetic and Alzheimer’s disease patients, changes in glucose transporter function and expression have been observed, but a possible link between the altered glucose transporter function and disease progress is missing. Future recognition of the role of new glucose transporter isoforms in the brain may provide a better understanding of brain glucose metabolism in normal and disease states. Elucidation of clinical pathological mechanisms related to glucose transport and metabolism may provide common links to the etiology of these two diseases. Considering these facts, in this review we provide a current understanding of the vital roles of a variety of glucose transporters in the normal, diabetic and Alzheimer’s disease brain.
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Affiliation(s)
- Kaushik Shah
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, 1300 S. Coulter Street, Amarillo, TX 79106, USA.
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15
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Liou GI, Ahmad S, Naime M, Fatteh N, Ibrahim AS. Role of adenosine in diabetic retinopathy. J Ocul Biol Dis Infor 2011; 4:19-24. [PMID: 23308298 DOI: 10.1007/s12177-011-9067-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 12/02/2011] [Indexed: 12/20/2022] Open
Abstract
In diabetic retinopathy (DR), abnormalities in vascular and neuronal function are closely related to the local production of inflammatory mediators whose potential source is microglia. Adenosine and its receptors have been shown to possess anti-inflammatory properties that have only recently been studied in DR. Here, we review recent studies that determined the roles of adenosine and its associated proteins, including equilibrative nucleoside transporters, adenosine receptors, and underlying signaling pathways in retinal complications associated with diabetes.
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16
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Ibrahim AS, El-Remessy AB, Matragoon S, Zhang W, Patel Y, Khan S, Al-Gayyar MM, El-Shishtawy MM, Liou GI. Retinal microglial activation and inflammation induced by amadori-glycated albumin in a rat model of diabetes. Diabetes 2011; 60:1122-33. [PMID: 21317295 PMCID: PMC3064086 DOI: 10.2337/db10-1160] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
OBJECTIVE During diabetes, retinal microglial cells are activated to release inflammatory cytokines that initiate neuronal loss and blood-retinal barrier breakdown seen in diabetic retinopathy (DR). The mechanism by which diabetes activates microglia to release those inflammatory mediators is unclear and was therefore elucidated. RESEARCH DESIGN AND METHODS Microglia activation was characterized in streptozocin-injected rats and in isolated microglial cells using immunofluorescence, enzyme-linked immunosorbent assay, RT-PCR, and Western blot analyses. RESULTS In 8-week diabetic retina, phospho-extracellular signal-related kinase (ERK) and P38 mitogen-activated protein kinases were localized in microglia, but not in Mueller cells or astrocytes. At the same time, Amadori-glycated albumin (AGA)-like epitopes were featured in the regions of microglia distribution, implicating a pathogenic effect on microglial activation. To test this, diabetic rats were treated intravitreally with A717, a specific AGA-neutralizing antibody, or murine IgG. Relative to nondiabetic rats, diabetic rats (IgG-treated) manifested 3.9- and 7.9-fold increases in Iba-1 and tumor necrosis factor (TNF)-α mRNAs, respectively. Treatment of diabetic rats with A717 significantly attenuated overexpression of these mRNAs. Intravitreal injection of AGA per se in normal rats resulted in increases of Iba-1 expression and TNF-α release. Guided by these results, a cultured retinal microglia model was developed to study microglial response after AGA treatment and the mechanistic basis behind this response. The results showed that formation of reactive oxygen species and subsequent activation of ERK and P38, but not Jun NH2-terminal kinase, are molecular events underpinning retinal microglial TNF-α release during AGA treatment. CONCLUSIONS These results provide new insights in understanding the pathogenesis of early DR, showing that the accumulated AGA within the diabetic retina elicits the microglial activation and secretion of TNF-α. Thus, intervention trials with agents that neutralize AGA effects may emerge as a new therapeutic approach to modulate early pathologic pathways long before the occurrence of vision loss among patients with diabetes.
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Affiliation(s)
- Ahmed S. Ibrahim
- Department of Ophthalmology, Medical College of Georgia, Augusta, Georgia
- Vision Discovery Institute, Medical College of Georgia, Augusta, Georgia
- Department of Biochemistry, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
| | - Azza B. El-Remessy
- Department of Ophthalmology, Medical College of Georgia, Augusta, Georgia
- Vision Discovery Institute, Medical College of Georgia, Augusta, Georgia
- Program in Clinical and Experimental Therapeutics, University of Georgia, Athens, Georgia
- VA Medical Center, Augusta, Georgia
| | - Suraporn Matragoon
- Program in Clinical and Experimental Therapeutics, University of Georgia, Athens, Georgia
- VA Medical Center, Augusta, Georgia
| | - Wenbo Zhang
- Vascular Biology Center, Medical College of Georgia, Augusta, Georgia
| | - Yogin Patel
- Department of Medicine, Medical College of Georgia, Augusta, Georgia
| | - Sohail Khan
- Department of Ophthalmology, Medical College of Georgia, Augusta, Georgia
| | - Mohammed M. Al-Gayyar
- Department of Biochemistry, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
- Program in Clinical and Experimental Therapeutics, University of Georgia, Athens, Georgia
- VA Medical Center, Augusta, Georgia
| | | | - Gregory I. Liou
- Department of Ophthalmology, Medical College of Georgia, Augusta, Georgia
- Vision Discovery Institute, Medical College of Georgia, Augusta, Georgia
- Corresponding author: Gregory I. Liou,
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17
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Abstract
Glaucoma is a leading cause of blindness. It is a multifactorial condition, the risk factors for which are increasingly well defined from large-scale epidemiological studies. One risk factor that remains controversial is the presence of diabetes. It has been proposed that diabetic eyes are at greater risk of injury from external stressors, such as elevated intraocular pressure. Alternatively, diabetes may cause ganglion cell loss, which becomes additive to a glaucomatous ganglion cell injury. Several clinical trials have considered whether a link exists between diabetes and glaucoma. In this review, we outline these studies and consider the causes for their lack of concordant findings. We also review the biochemical and cellular similarities between the two conditions. Moreover, we review the available literature that attempts to answer the question of whether the presence of diabetes increases the risk of developing glaucoma. At present, laboratory studies provide robust evidence for an association between diabetes and glaucoma.
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Affiliation(s)
- Vickie H Y Wong
- Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, VIC 3010, Australia
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18
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Gandhi GK, Ball KK, Cruz NF, Dienel GA. Hyperglycaemia and diabetes impair gap junctional communication among astrocytes. ASN Neuro 2010; 2:e00030. [PMID: 20396375 DOI: 10.1042/AN20090048] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Revised: 01/03/2010] [Accepted: 01/05/2010] [Indexed: 01/21/2023] Open
Abstract
Sensory and cognitive impairments have been documented in diabetic humans and
animals, but the pathophysiology of diabetes in the central nervous system is
poorly understood. Because a high glucose level disrupts gap junctional
communication in various cell types and astrocytes are extensively coupled by
gap junctions to form large syncytia, the influence of experimental diabetes on
gap junction channel-mediated dye transfer was assessed in astrocytes in tissue
culture and in brain slices from diabetic rats. Astrocytes grown in
15–25 mmol/l glucose had a slow-onset, poorly reversible decrement in
gap junctional communication compared with those grown in 5.5 mmol/l glucose.
Astrocytes in brain slices from adult STZ (streptozotocin)-treated rats at
20–24 weeks after the onset of diabetes also exhibited reduced dye
transfer. In cultured astrocytes grown in high glucose, increased oxidative
stress preceded the decrement in dye transfer by several days, and gap
junctional impairment was prevented, but not rescued, after its manifestation by
compounds that can block or reduce oxidative stress. In sharp contrast with
these findings, chaperone molecules known to facilitate protein folding could
prevent and rescue gap junctional impairment, even in the presence of elevated
glucose level and oxidative stress. Immunostaining of Cx (connexin) 43 and 30,
but not Cx26, was altered by growth in high glucose. Disruption of astrocytic
trafficking of metabolites and signalling molecules may alter interactions among
astrocytes, neurons and endothelial cells and contribute to changes in brain
function in diabetes. Involvement of the microvasculature may contribute to
diabetic complications in the brain, the cardiovascular system and other
organs.
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Key Words
- 4-PBA, 4-phenylbutyric acid
- 6-NBDG, 6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxyglucose
- Cx, connexin
- DCF, 2′,7′-dichlorodihydrofluorescein
- DIC, differential interference contrast
- DMEM, Dulbecco's modified Eagle's medium
- ER, endoplasmic reticulum
- FBS, fetal bovine serum
- LYCH, Lucifer Yellow CH
- LYVS, Lucifer Yellow VS
- MnTBAP, manganese(III) tetrakis (4-benzoic acid) porphyrin chloride
- NA, numerical aperture
- NOS, nitric oxide synthase
- PKC, protein kinase C
- RNS, reactive nitrogen species
- ROS, reactive oxygen species
- STZ, streptozotocin
- TMAO, trimethylamine N-oxide dihydrate
- TUDCA, tauroursodeoxycholic acid
- aCSF, artificial cerebrospinal fluid
- astrocyte
- carboxy-DCF-DA, carboxy DCF diacetate
- connexin (Cx)
- dBcAMP, dibutyryl cAMP
- diabetes
- gap junction
- hyperglycaemia
- l-NAME, l-Nω-nitro-l-arginine methyl ester
- streptozotocin
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19
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Acar N, Bonhomme B, Joffre C, Bron AM, Creuzot-Garcher C, Bretillon L, Doly M, Chardigny JM. The retina is more susceptible than the brain and the liver to the incorporation oftransisomers of DHA in rats consumingtransisomers of alpha-linolenic acid. ACTA ACUST UNITED AC 2006; 46:515-25. [PMID: 17107641 DOI: 10.1051/rnd:2006033] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Trans polyunsaturated fatty acids are formed during heat treatments of vegetable oils from polyunsaturated fatty acids containing cis double bonds. After dietary intake, they are distributed in the body and are incorporated into nervous tissues including the retina. Since nervous tissues are known to be rich in n-3 fatty acids such as docosahexaenoic acid (DHA), we studied the ability of the retina and the brain to incorporate trans isomers of DHA formed in vivo from the dietary precursor trans alpha-linolenic acid. Wistar rats were fed with trans isomers of alpha-linolenic acid for 21 months. A linear incorporation of trans DHA and a decrease in cis DHA was observed in the retina, whereas no major changes were observed in the brain. In parallel to the modifications in retinal cis and trans DHA levels, the retinal functionality evaluated by the electroretinogram showed defects in animals that consumed trans alpha-linolenic acid. These results suggest that the mechanisms leading to the incorporation of cis and trans fatty acids are quite different in the retina when compared to the brain and the liver, the retina being more susceptible to changes in the dietary lipid contribution.
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Affiliation(s)
- Niyazi Acar
- INRA, Lipid Nutrition Unit, 17, rue Sully, BP86510, Dijon Cedex, 21065 France.
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20
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Abstract
Recent mining of the human and mouse genomes, use of yeast genetics, and detailed analyses of several biochemical pathways, have resulted in the identification of many new roles for ubiquitin-proteasome mediated degradation of proteins. In the context of last year's award of Noble Prize (Chemistry) work, the ubiquitin and ubiquitin-like modifications are increasingly recognized as key regulatory events in health and disease. Although the ATP-dependent ubiquitin-proteasome system has evolved as premier cellular proteolytic machinery, dysregulation of this system by several different mechanisms leads to inappropriate degradation of specific proteins and pathological consequences. While aberrations in the ubiquitin-proteasome pathway have been implicated in certain malignancies and neurodegenerative disorders, recent studies indicate a role for this system in the pathogenesis of diabetes and its complications. Inappropriate degradation of insulin signaling molecules such as insulin receptor substrates (IRS-1 and IRS-2) has been demonstrated in experimental diabetes, mediated in part through the up-regulation of suppressors of cytokine signaling (SOCS). It appears that altered ubiquitin-proteasome system might be one of the molecular mechanisms of insulin resistance in many pathological situations. Drugs that modulate the SOCS action and/or proteasomal degradation of proteins could become novel agents for the treatment of insulin resistance and Type 2 diabetes.
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Affiliation(s)
- Muthuswamy Balasubramanyam
- Department of Cell and Molecular Biology, Madras Diabetes Research Foundation, 6B, Conran Smith Road, Gopalapuram, Chennai 600 086, India.
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21
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Wiernsperger NF. Is non-insulin dependent glucose uptake a therapeutic alternative? Part 2: Do such mechanisms fulfil the required combination of power and tolerability? Diabetes & Metabolism 2005; 31:521-5. [PMID: 16357799 DOI: 10.1016/s1262-3636(07)70226-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The worldwide burden of diabetes, the unavoidable worsening which is observed in long-term clinical trials despite treatment and the close link between glycaemia and microangiopathy appeal for much stronger treatment strategies. This, in turn, either requires polypharmacy (with new risks) or new, more powerful drugs to be invented. The first part of this review dealt with a thorough analysis of pros and cons for some selected pathways which could potentially increase glucose uptake without necessitating insulin. The choice of such targets for developing completely new drugs, however, requires a favourable background from existing tentatives with either drugs or cell biology approaches. Moreover, because vascular complications are what must ultimately be avoided when treating diabetic patients, we must be sure that increasing glucose uptake in a fashion which is no more controlled by normal physiology is compatible with the physiology of vascular cells (long-term tolerance). The aspect of drug side-effects must therefore be considered systematically. For reasons which are individually developed, it appears that each of the potential pathways analyzed either lacks sufficient power and/or is likely to induce side effects which are not acceptable for long-term application. The fact that GLUT-1 transporters are ubiquitously distributed even extends this cardinal question to the general principle of increasing glucose uptake. In conclusion a precise evaluation suggests that, although non-insulin dependent glucose uptake represents (3/4) of whole body glucose transport, it is difficult to consider such mechanisms able to generate a new treatment fulfilling the unavoidable request of combined efficacy and tolerability.
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Affiliation(s)
- N F Wiernsperger
- INSERM UMR 585, Bâtiment Louis Pasteur, INSA Lyon, boulevard J. Chapelle, 69621 Villeurbanne Cedex, France.
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22
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Patton N, Aslam T, Macgillivray T, Pattie A, Deary IJ, Dhillon B. Retinal vascular image analysis as a potential screening tool for cerebrovascular disease: a rationale based on homology between cerebral and retinal microvasculatures. J Anat 2005; 206:319-48. [PMID: 15817102 PMCID: PMC1571489 DOI: 10.1111/j.1469-7580.2005.00395.x] [Citation(s) in RCA: 499] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The retinal and cerebral microvasculatures share many morphological and physiological properties. Assessment of the cerebral microvasculature requires highly specialized and expensive techniques. The potential for using non-invasive clinical assessment of the retinal microvasculature as a marker of the state of the cerebrovasculature offers clear advantages, owing to the ease with which the retinal vasculature can be directly visualized in vivo and photographed due to its essential two-dimensional nature. The use of retinal digital image analysis is becoming increasingly common, and offers new techniques to analyse different aspects of retinal vascular topography, including retinal vascular widths, geometrical attributes at vessel bifurcations and vessel tracking. Being predominantly automated and objective, these techniques offer an exciting opportunity to study the potential to identify retinal microvascular abnormalities as markers of cerebrovascular pathology. In this review, we describe the anatomical and physiological homology between the retinal and cerebral microvasculatures. We review the evidence that retinal microvascular changes occur in cerebrovascular disease and review current retinal image analysis tools that may allow us to use different aspects of the retinal microvasculature as potential markers for the state of the cerebral microvasculature.
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Affiliation(s)
- Niall Patton
- Princess Alexandra Eye Pavilion, Chalmers Street, Edinburgh, UK.
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23
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Abstract
Diabetes is associated with extensive microvascular pathology and decreased expression of the glucose transporter (GLUT-1) in retina, but not brain. To explore the basis of these differences, the authors simultaneously measured glucose influx (micromol x g(-1) x min(-1)) and blood flow (mL x g(-1) x min(-1)) in retina and brain cortex of nondiabetic control rats (normoglycemic and acute-hyperglycemic) and in rats with streptozotocin-induced diabetes (with or without aminoguanidine (AMG) treatment) using a single-pass, dual-label indicator method. In addition, tissue glucose and adenosine triphosphate (nmol/mg dry weight) levels were measured. Glucose influx in retina exceeded that of cortex by about threefold for both the nondiabetic and diabetic groups. In contrast, blood flow in retina was significantly lower than in cortex by about threefold for each group. Retinal and cortical glucose influx in the diabetic rats was lower than in the nondiabetic acute-hyperglycemic group, but not in the normoglycemic group. Blood flow in these tissues remained relatively unchanged with glycemic conditions. The glucose levels in the diabetic retina (aminoguanidine untreated and aminoguanidine treated) were fourfold to sixfold greater than the nondiabetic retina. The cortical glucose levels remained unchanged in all groups. These data suggest that the accumulation of glucose in the diabetic retina cannot be explained by increased endothelial-glucose uptake or increased vascular membrane permeability.
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Affiliation(s)
- Michelle A Puchowicz
- Department of Anatomy, Case Western Reserve University, School of Medicine, Cleveland, OH 44106-4938, USA
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24
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Nakamura M, Barber AJ, Antonetti DA, LaNoue KF, Robinson KA, Buse MG, Gardner TW. Excessive hexosamines block the neuroprotective effect of insulin and induce apoptosis in retinal neurons. J Biol Chem 2001; 276:43748-55. [PMID: 11560942 DOI: 10.1074/jbc.m108594200] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
In addition to microvascular abnormalities, neuronal apoptosis occurs early in diabetic retinopathy, but the mechanism is unknown. Insulin may act as a neurotrophic factor in the retina via the phosphoinositide 3-kinase/Akt pathway. Excessive glucose flux through the hexosamine biosynthetic pathway (HBP) is implicated in the development of insulin resistance in peripheral tissues and diabetic complications such as nephropathy. We tested whether increased glucose flux through the HBP perturbs insulin action and induces apoptosis in retinal neuronal cells. Exposure of R28 cells, a model of retinal neurons, to 20 mm glucose for 24 h attenuated the ability of 10 nm insulin to rescue them from serum deprivation-induced apoptosis and to phosphorylate Akt compared with 5 mm glucose. Glucosamine not only impaired the neuroprotective effect of insulin but also induced apoptosis in R28 cells in a dose-dependent fashion. UDP-N-acetylhexosamines (UDP-HexNAc), end products of the HBP, were increased approximately 2- and 15-fold after a 24-h incubation in 20 mm glucose and 1.5 mm glucosamine, respectively. Azaserine, a glutamine:fructose-6-phosphate amidotransferase inhibitor, reversed the effect of 20 mm glucose, but not that of 1.5 mm glucosamine, on attenuation of the ability of insulin to promote cell survival and phosphorylate Akt as well as accumulation of UDP-HexNAc. Glucosamine also impaired insulin receptor processing in a dose-dependent manner but did not decrease ATP content. By contrast, in L6 muscle cells, glucosamine impaired insulin receptor processing but did not induce apoptosis. These results suggest that the excessive glucose flux through the HBP may direct retinal neurons to undergo apoptosis in a bimodal fashion; i.e. via perturbation of the neuroprotective effect of insulin mediated by Akt and via induction of apoptosis possibly by altered glycosylation of proteins. The HBP may be involved in retinal neurodegeneration in diabetes.
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Affiliation(s)
- M Nakamura
- Pennsylvania State Retina Research Group, The Ulerich Ophthalmology Research Center, the Department of Ophthalmology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA
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25
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Gardner TW, Antonetti DA, Barber AJ, LaNoue KF, Nakamura M. New insights into the pathophysiology of diabetic retinopathy: potential cell-specific therapeutic targets. Diabetes Technol Ther 2000; 2:601-8. [PMID: 11469624 DOI: 10.1089/15209150050502023] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Diabetic retinopathy, a leading cause of vision impairment, is classically defined by its vascular lesions. This review examines how diabetes affects vascular cells, as well as neurons, macroglia, and microglia. The cellular and clinical elements of diabetic retinopathy have many features of chronic inflammation. Understanding the individual cell-specific and global inflammatory changes in the retina may lead to novel therapeutic approaches to prevent vision loss.
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Affiliation(s)
- T W Gardner
- Department of Ophthalmology, Penn State University College of Medicine, Hershey, Pennsylvania 17033, USA.
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