1
|
Sadikan MZ, Abdul Nasir NA, Lambuk L, Mohamud R, Reshidan NH, Low E, Singar SA, Mohmad Sabere AS, Iezhitsa I, Agarwal R. Diabetic retinopathy: a comprehensive update on in vivo, in vitro and ex vivo experimental models. BMC Ophthalmol 2023; 23:421. [PMID: 37858128 PMCID: PMC10588156 DOI: 10.1186/s12886-023-03155-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 09/26/2023] [Indexed: 10/21/2023] Open
Abstract
Diabetic retinopathy (DR), one of the leading causes of visual impairment and blindness worldwide, is one of the major microvascular complications in diabetes mellitus (DM). Globally, DR prevalence among DM patients is 25%, and 6% have vision-threatening problems among them. With the higher incidence of DM globally, more DR cases are expected to be seen in the future. In order to comprehend the pathophysiological mechanism of DR in humans and discover potential novel substances for the treatment of DR, investigations are typically conducted using various experimental models. Among the experimental models, in vivo models have contributed significantly to understanding DR pathogenesis. There are several types of in vivo models for DR research, which include chemical-induced, surgical-induced, diet-induced, and genetic models. Similarly, for the in vitro models, there are several cell types that are utilised in DR research, such as retinal endothelial cells, Müller cells, and glial cells. With the advancement of DR research, it is essential to have a comprehensive update on the various experimental models utilised to mimic DR environment. This review provides the update on the in vitro, in vivo, and ex vivo models used in DR research, focusing on their features, advantages, and limitations.
Collapse
Affiliation(s)
- Muhammad Zulfiqah Sadikan
- Department of Pharmacology, Faculty of Medicine, Manipal University College Malaysia (MUCM), Bukit Baru, 75150, Melaka, Malaysia
| | - Nurul Alimah Abdul Nasir
- Centre for Neuroscience Research (NeuRon), Faculty of Medicine, Universiti Teknologi MARA, 47000, Sungai Buloh, Selangor, Malaysia.
| | - Lidawani Lambuk
- Department of Immunology, School of Medical Sciences, Universiti Sains Malaysia, 16150, Kubang Kerian, Kelantan, Malaysia
| | - Rohimah Mohamud
- Department of Immunology, School of Medical Sciences, Universiti Sains Malaysia, 16150, Kubang Kerian, Kelantan, Malaysia
| | - Nur Hidayah Reshidan
- School of Biology, Faculty of Applied Sciences, Universiti Teknologi MARA, 40450, Shah Alam, Selangor, Malaysia
| | - Evon Low
- Ageing Biology Centre, Newcastle University, NE1 7RU, Newcastle upon Tyne, UK
| | - Saiful Anuar Singar
- Department of Nutrition and Integrative Physiology, College of Health and Human Sciences, Florida State University, 32306, Tallahassee, FL, USA
| | - Awis Sukarni Mohmad Sabere
- Kulliyyah of Pharmacy, International Islamic University Malaysia, Jalan Sultan Ahmad Shah, Bandar Indera Mahkota, 25200, Kuantan, Pahang, Malaysia
| | - Igor Iezhitsa
- School of Medicine, International Medical University, 57000, Bukit Jalil, Kuala Lumpur, Malaysia
- Department of Pharmacology and Bioinformatics, Volgograd State Medical University, Pavshikh Bortsov sq. 1, 400131 , Volgograd, Russian Federation
| | - Renu Agarwal
- School of Medicine, International Medical University, 57000, Bukit Jalil, Kuala Lumpur, Malaysia
| |
Collapse
|
2
|
Pitale PM, Gorbatyuk MS. Diabetic Retinopathy: From Animal Models to Cellular Signaling. Int J Mol Sci 2022; 23:ijms23031487. [PMID: 35163410 PMCID: PMC8835767 DOI: 10.3390/ijms23031487] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 01/24/2022] [Accepted: 01/26/2022] [Indexed: 12/24/2022] Open
Abstract
Diabetic retinopathy (DR) is an ocular complication of diabetes mellitus (DM), a metabolic disorder characterized by elevation in blood glucose level. The pathogenesis of DR includes vascular, neuronal, and inflammatory components leading to activation of complex cellular molecular signaling. If untreated, the disease can culminate in vision loss that eventually leads to blindness. Animal models mimicking different aspects of DM complications have been developed to study the development and progression of DR. Despite the significant contribution of the developed DR models to discovering the mechanisms of DR and the recent achievements in the research field, the sequence of cellular events in diabetic retinas is still under investigation. Partially, this is due to the complexity of molecular mechanisms, although the lack of availability of models that adequately mimic all the neurovascular pathobiological features observed in patients has also contributed to the delay in determining a precise molecular trigger. In this review, we provide an update on the status of animal models of DR to help investigators choose an appropriate system to validate their hypothesis. We also discuss the key cellular and physiological events of DR in these models.
Collapse
Affiliation(s)
- Priyamvada M. Pitale
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX 77030, USA;
| | - Marina S. Gorbatyuk
- Department of Optometry and Vision Science, School of Optometry, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Correspondence: ; Tel.: +1-205-934-6762; Fax: +1-205-934-3425
| |
Collapse
|
3
|
Quiroz J, Yazdanyar A. Animal models of diabetic retinopathy. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:1272. [PMID: 34532409 PMCID: PMC8421981 DOI: 10.21037/atm-20-6737] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Accepted: 12/23/2020] [Indexed: 12/16/2022]
Abstract
The retina is the posterior neuro-integrated layer of the eye that conducts impulses induced by light to the optic nerve for human vision. Diseases of the retina often leads to diminished vision and in some cases blindness. Diabetes mellitus (DM) is a worldwide public health issue and globally, there is an estimated 463 million people that are affected by DM and its consequences. Diabetic retinopathy (DR) is a blinding complication of chronic uncontrolled DM and is the most common cause of blindness in the United States between the ages 24-75. It is estimated that the global prevalence of DR will increase to 191.0 million by 2030, of those 56.3 million possessing vision-threatening diabetic retinopathy (VTDR). For the most part, current treatment modalities control the complications of DR without addressing the underlying pathophysiology of the disease. Therefore, there is an unmet need for new therapeutics that not only repair the damaged retinal tissue, but also reverse the course of DR. The key element in developing these treatments is expanding our basic knowledge by studying DR pathogenesis in animal models of proliferative and non-proliferative DR (PDR and NPDR). There are numerous models available for the research of both PDR and NPDR with substantial overlap. Animal models available include those with genetic backgrounds prone to hyperglycemic states, immunologic etiologies, or environmentally induced disease. In this review we aimed to comprehensively summarize the available animal models for DR while also providing insight to each model's ocular therapeutic potential for drug discovery.
Collapse
Affiliation(s)
- Jose Quiroz
- Medical Scientist Training Program, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Amirfarbod Yazdanyar
- Department of Ophthalmology and Visual Sciences, State University of New York (SUNY), Upstate Medical University, Syracuse, NY, USA
| |
Collapse
|
4
|
Fernandez-Bueno I, Diebold Y. Ocular findings in Zucker Diabetic Fatty rats emphasize the key role of neuroglia degeneration in diabetic retinopathy pathophysiology. Neural Regen Res 2018; 13:239-240. [PMID: 29557371 PMCID: PMC5879893 DOI: 10.4103/1673-5374.226391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Ivan Fernandez-Bueno
- Instituto Universitario de Oftalmobiología Aplicada, University of Valladolid, Valladolid; Red Temática de Investigación Cooperativa en Salud (RETICS), Oftared, Instituto de Salud Carlos III, Madrid, Spain
| | - Yolanda Diebold
- Instituto Universitario de Oftalmobiología Aplicada, University of Valladolid; Biomedical Research Networking Center on Bioengineering, Biomaterials and Nanomedicine, CIBER-BBN, Valladolid, Spain
| |
Collapse
|
5
|
Abstract
PURPOSE OF REVIEW Diabetic retinopathy (DR) is one of the most common complications associated with chronic hyperglycemia seen in patients with diabetes mellitus. While many facets of DR are still not fully understood, animal studies have contributed significantly to understanding the etiology and progression of human DR. This review provides a comprehensive discussion of the induced and genetic DR models in different species and the advantages and disadvantages of each model. RECENT FINDINGS Rodents are the most commonly used models, though dogs develop the most similar morphological retinal lesions as those seen in humans, and pigs and zebrafish have similar vasculature and retinal structures to humans. Nonhuman primates can also develop diabetes mellitus spontaneously or have focal lesions induced to simulate retinal neovascular disease observed in individuals with DR. DR results in vascular changes and dysfunction of the neural, glial, and pancreatic β cells. Currently, no model completely recapitulates the full pathophysiology of neuronal and vascular changes that occur at each stage of diabetic retinopathy; however, each model recapitulates many of the disease phenotypes.
Collapse
Affiliation(s)
- Ana Maria Olivares
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, MA 02114 USA
| | - Kristen Althoff
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, MA 02114 USA
| | - Gloria Fanghua Chen
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, MA 02114 USA
| | - Siqi Wu
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, MA 02114 USA
| | | | | | - Neena Haider
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, MA 02114 USA
| |
Collapse
|
6
|
Abstract
Diabetic retinopathy (DR) is one of today's main causes of blindness in numerous developed countries worldwide. The underlying pathogenesis of DR is complex and not well understood, thus impeding development of specific, effective treatment modalities. Consequently, the use of animal models of DR is of critical importance for investigating the pathogenesis of and treatment for DR. While rats and mice are the most commonly used animal models of DR, the zebrafish now appears to be a promising model. Nonhuman primates and humans have similar eye structures, and both can develop spontaneous diabetes mellitus (DM). Although various traditionally used animal models of DR undergo a number of pathological changes similar to those of human DR, several human variations, e.g. retinal neovascularization, cannot yet be fully mimicked in any existing animal model of DM. Since both the animal models and the methods chosen for inducing DR have great influence on experimental results, a clear understanding of available animal models is vital for planning an experimental design. In this review, we summarize the mechanisms, methodologies and pros and cons of the most commonly used animal models of DR.
Collapse
Affiliation(s)
- Xiaoyan Jiang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University , Guangzhou , P.R. China
| | | | | |
Collapse
|
7
|
Mi XS, Yuan TF, Ding Y, Zhong JX, So KF. Choosing preclinical study models of diabetic retinopathy: key problems for consideration. DRUG DESIGN DEVELOPMENT AND THERAPY 2014; 8:2311-9. [PMID: 25429204 PMCID: PMC4242133 DOI: 10.2147/dddt.s72797] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Diabetic retinopathy (DR) is the most common complication of diabetes mellitus in the eye. Although the clinical treatment for DR has already developed to a relative high level, there are still many urgent problems that need to be investigated in clinical and basic science. Currently, many in vivo animal models and in vitro culture systems have been applied to solve these problems. Many approaches have also been used to establish different DR models. However, till now, there has not been a single study model that can clearly and exactly mimic the developmental process of the human DR. Choosing the suitable model is important, not only for achieving our research goals smoothly, but also, to better match with different experimental proposals in the study. In this review, key problems for consideration in choosing study models of DR are discussed. These problems relate to clinical relevance, different approaches for establishing models, and choice of different species of animals as well as of the specific in vitro culture systems. Attending to these considerations will deepen the understanding on current study models and optimize the experimental design for the final goal of preventing DR.
Collapse
Affiliation(s)
- Xue-Song Mi
- Department of Ophthalmology, First Affiliated Hospital of Jinan University, Guangzhou, Guangdong, People's Republic of China ; Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, People's Republic of China
| | - Ti-Fei Yuan
- School of Psychology, Nanjing Normal University, Nanjing, People's Republic of China ; Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Yong Ding
- Department of Ophthalmology, First Affiliated Hospital of Jinan University, Guangzhou, Guangdong, People's Republic of China
| | - Jing-Xiang Zhong
- Department of Ophthalmology, First Affiliated Hospital of Jinan University, Guangzhou, Guangdong, People's Republic of China
| | - Kwok-Fai So
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong ; Guangdong-Hongkong-Macau Institute of Central Nervous System, Jinan University, Guangzhou, People's Republic of China
| |
Collapse
|
8
|
Robinson R, Barathi VA, Chaurasia SS, Wong TY, Kern TS. Update on animal models of diabetic retinopathy: from molecular approaches to mice and higher mammals. Dis Model Mech 2013; 5:444-56. [PMID: 22730475 PMCID: PMC3380708 DOI: 10.1242/dmm.009597] [Citation(s) in RCA: 193] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Diabetic retinopathy (DR) is the most common microvascular complication of diabetes and one of the major causes of blindness worldwide. The pathogenesis of DR has been investigated using several animal models of diabetes. These models have been generated by pharmacological induction, feeding a galactose diet, and spontaneously by selective inbreeding or genetic modification. Among the available animal models, rodents have been studied most extensively owing to their short generation time and the inherited hyperglycemia and/or obesity that affect certain strains. In particular, mice have proven useful for studying DR and evaluating novel therapies because of their amenability to genetic manipulation. Mouse models suitable for replicating the early, non-proliferative stages of the retinopathy have been characterized, but no animal model has yet been found to demonstrate all of the vascular and neural complications that are associated with the advanced, proliferative stages of DR that occur in humans. In this review, we summarize commonly used animal models of DR, and briefly outline the in vivo imaging techniques used for characterization of DR in these models. Through highlighting the ocular pathological findings, clinical implications, advantages and disadvantages of these models, we provide essential information for planning experimental studies of DR that will lead to new strategies for its prevention and treatment.
Collapse
|
9
|
Bharadwaj AS, Appukuttan B, Wilmarth PA, Pan Y, Stempel AJ, Chipps TJ, Benedetti EE, Zamora DO, Choi D, David LL, Smith JR. Role of the retinal vascular endothelial cell in ocular disease. Prog Retin Eye Res 2013; 32:102-80. [PMID: 22982179 PMCID: PMC3679193 DOI: 10.1016/j.preteyeres.2012.08.004] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2012] [Revised: 08/23/2012] [Accepted: 08/24/2012] [Indexed: 12/14/2022]
Abstract
Retinal endothelial cells line the arborizing microvasculature that supplies and drains the neural retina. The anatomical and physiological characteristics of these endothelial cells are consistent with nutritional requirements and protection of a tissue critical to vision. On the one hand, the endothelium must ensure the supply of oxygen and other nutrients to the metabolically active retina, and allow access to circulating cells that maintain the vasculature or survey the retina for the presence of potential pathogens. On the other hand, the endothelium contributes to the blood-retinal barrier that protects the retina by excluding circulating molecular toxins, microorganisms, and pro-inflammatory leukocytes. Features required to fulfill these functions may also predispose to disease processes, such as retinal vascular leakage and neovascularization, and trafficking of microbes and inflammatory cells. Thus, the retinal endothelial cell is a key participant in retinal ischemic vasculopathies that include diabetic retinopathy and retinopathy of prematurity, and retinal inflammation or infection, as occurs in posterior uveitis. Using gene expression and proteomic profiling, it has been possible to explore the molecular phenotype of the human retinal endothelial cell and contribute to understanding of the pathogenesis of these diseases. In addition to providing support for the involvement of well-characterized endothelial molecules, profiling has the power to identify new players in retinal pathologies. Findings may have implications for the design of new biological therapies. Additional progress in this field is anticipated as other technologies, including epigenetic profiling methods, whole transcriptome shotgun sequencing, and metabolomics, are used to study the human retinal endothelial cell.
Collapse
Affiliation(s)
| | | | - Phillip A. Wilmarth
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University
| | - Yuzhen Pan
- Casey Eye Institute, Oregon Health & Science University
| | | | | | | | | | - Dongseok Choi
- Department of Public Health and Preventive Medicine, Oregon Health & Science University
| | - Larry L. David
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University
| | - Justine R. Smith
- Casey Eye Institute, Oregon Health & Science University
- Department of Cell & Developmental Biology, Oregon Health & Science University
| |
Collapse
|
10
|
Lai AKW, Lo ACY. Animal models of diabetic retinopathy: summary and comparison. J Diabetes Res 2013; 2013:106594. [PMID: 24286086 PMCID: PMC3826427 DOI: 10.1155/2013/106594] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 09/02/2013] [Accepted: 09/02/2013] [Indexed: 12/16/2022] Open
Abstract
Diabetic retinopathy (DR) is a microvascular complication associated with chronic exposure to hyperglycemia and is a major cause of blindness worldwide. Although clinical assessment and retinal autopsy of diabetic patients provide information on the features and progression of DR, its underlying pathophysiological mechanism cannot be deduced. In order to have a better understanding of the development of DR at the molecular and cellular levels, a variety of animal models have been developed. They include pharmacological induction of hyperglycemia and spontaneous diabetic rodents as well as models of angiogenesis without diabetes (to compensate for the absence of proliferative DR symptoms). In this review, we summarize the existing protocols to induce diabetes using STZ. We also describe and compare the pathological presentations, in both morphological and functional aspects, of the currently available DR animal models. The advantages and disadvantages of using different animals, ranging from zebrafish, rodents to other higher-order mammals, are also discussed. Until now, there is no single model that displays all the clinical features of DR as seen in human. Yet, with the understanding of the pathological findings in these animal models, researchers can select the most suitable models for mechanistic studies or drug screening.
Collapse
Affiliation(s)
- Angela Ka Wai Lai
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Amy C. Y. Lo
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
- Research Center of Heart, Brain, Hormone and Healthy Aging, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
- *Amy C. Y. Lo:
| |
Collapse
|
11
|
Díaz-Flores L, Gutiérrez R, García MP, Díaz-Flores L, Valladares F, Madrid JF. Ultrastructure of myopericytoma: a continuum of transitional phenotypes of myopericytes. Ultrastruct Pathol 2012; 36:189-94. [PMID: 22559047 DOI: 10.3109/01913123.2012.655855] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The authors report the ultrastructural characteristics of myopericytoma, a recently described variant of perivascular (pericytic) tumors, mainly with regard to their myopericytic cells and vessels. Myopericytes range between pericytes and vascular smooth muscle cells (SMCs) in a morphologic continuum. The principal findings of the intermediate phenotypes are (1) elongated or annular morphology with processes of varying length and thickness (usually long and thin); (2) a continuous, irregularly thickened and zonally duplicated basement membrane; (3) heterocellular "peg and socket" junctions with neighboring endothelial cells, and scarce specialized junctions between myopericytes; (4) numerous micropinocytotic vesicles, whether continuous or forming focal rows; (5) abundant thin microfilaments, grouped in bundles with dense bodies and adhesion plaques; (6) poorly developed synthetic system (RER and Golgi); (7) pseudointracellular bodies formed by invagination of basement and plasma membranes, with numerous endocytic vesicles; and (8) zones of cytoplasmic rarefaction near micropinocytotic vesicles and intracellular organelles. The ultrastructure of myopericytes therefore makes it possible to distinguish them from pericytes, SMCs, and fibroblast/myofibroblasts, which is useful for myopericytoma diagnosis. The main pattern of the vessels, with perivascular concentric and multilayered growth of myopericytes (a thick wall in contrast to a small lumen) and lack of elastic material, also supports an intermediate form between pericytic and muscular microvasculature. The presence of myopericytes more similar to SMCs and of hemangiopericytoma-like vessels concurs with transitional forms with angioleyomyoma and true hemangiopericytoma, histogenetically representing a morphologic continuum for the perivascular tumors.
Collapse
Affiliation(s)
- L Díaz-Flores
- Department of Anatomy, Pathology, Histology and Radiology, Faculty of Medicine, University of La Laguna, Tenerife, Spain.
| | | | | | | | | | | |
Collapse
|
12
|
Barber AJ, Gardner TW, Abcouwer SF. The significance of vascular and neural apoptosis to the pathology of diabetic retinopathy. Invest Ophthalmol Vis Sci 2011; 52:1156-63. [PMID: 21357409 DOI: 10.1167/iovs.10-6293] [Citation(s) in RCA: 291] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The most striking features of diabetic retinopathy are the vascular abnormalities that are apparent by fundus examination. There is also strong evidence that diabetes causes apoptosis of neural and vascular cells in the retina. Thus, there is good reason to define diabetic retinopathy as a form of chronic neurovascular degeneration. In keeping with the gradual onset of retinopathy in humans, the rate of cell loss in the animal models is insidious, even in uncontrolled diabetes. This is not surprising given that a sustained high rate of cell loss without regeneration would soon lead to catastrophic tissue destruction. The consequences of ongoing cell death are difficult to detect, and even the quantification of cumulative cell loss requires painstaking histology and microscopy. This subtle cell loss raises the issue of the relevance of the phenomenon to the progression of diabetic retinopathy and the ultimate loss of vision. Neuronal function may be compromised in advance of apoptosis, contributing to an early deterioration of vision. Here we review some of the evidence supporting apoptotic cell death as a contributing mechanism of diabetic retinopathy, explore some of the potential causes, and discuss the potential links between apoptosis and loss of visual function in diabetic retinopathy.
Collapse
Affiliation(s)
- Alistair J Barber
- Department of Ophthalmology, Penn State Hershey Eye Center, Penn State Hershey College of Medicine, Hershey, Pennsylvania 17033, USA.
| | | | | |
Collapse
|
13
|
Matsumoto Y, Torimoto K, Matsuyoshi H, Hirayama A, Fujimoto K, Yoshimura N, Hirao Y. Long-term effects of diabetes mellitus on voiding function in a new model of type 2 diabetes mellitus, the Spontaneously Diabetic Torii (SDT) rat. ACTA ACUST UNITED AC 2010; 30:331-5. [PMID: 20051641 DOI: 10.2220/biomedres.30.331] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The spontaneously diabetic Torii (SDT) rat has recently been established as a model of type 2 diabetes mellitus (DM). The usefulness of this rat model for the study of diabetic voiding dysfunction was investigated. Male SDT rats and male Sprague-Dawley (SD) rats were used. Voiding function was evaluated by a metabolic cage study and cystometry. Total voided volume for 24 h, mean voided volume, and urinary frequency for 24 h were significantly greater in SDT rats at the age of 36 weeks. From cystometry mean inter-micturition interval (IMI) was significantly longer in SDT rats at the age of 22 and 36 weeks. In SDT rats mean IMI was significantly longer at the age of 36 weeks than at the age of 22 weeks. Mean voiding pressure was significantly higher in SDT rats at the age of 22 and 36 weeks. In the present study, SDT rats showed typical diabetic voiding dysfunction similar to other diabetic rat models. It was suggested that activity of the bladder afferent pathways is decreased and the urethral relaxation mechanism is impaired in SDT rats. In addition, SDT rats are suitable to study chronic diabetic voiding dysfunction because they survive without insulin treatment for as long as 60 weeks.
Collapse
Affiliation(s)
- Yoshihiro Matsumoto
- Department of Urology, School of Medicine, Nara Medical University, Kashihara, Japan
| | | | | | | | | | | | | |
Collapse
|
14
|
Tsuji N, Matsuura T, Ozaki K, Sano T, Narama I. Diabetic retinopathy and choroidal angiopathy in diabetic rats (WBN/Kob). Exp Anim 2010; 58:481-7. [PMID: 19897931 DOI: 10.1538/expanim.58.481] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Retinopathy and choroidal angiopathy were both detected in aged male rats of the WBN/Kob strain with sustained diabetes. Hyperglycemia and glucosuria were found starting from 12 months of age and lasted through 24 months of age. Macroscopically, the vitreous body was partially or entirely replaced by white mass in 3 of 9 diabetic males. Histopathologically, the intravitreal white mass consisted of collagen fibers accompanied by numbers of newly formed vessels. Intraretinal angiopathy was accompanied with newly formed vessels, which were observed within the retina in 5 of 9 diabetic males, and marked hyalinization of intraretinal vessels was detected in 6 of 9 males irrespective of the presence of intravitreal neovascularization. Furthermore, hyperglycemia-related choroidal angiopathy was also seen with newly formed blood vessels originating from the choroid penetrating the retinal pigment epithelial layer and invading the retina in 8 of 9 diabetic males. Focal proliferation or degeneration of the pigment epithelial cells was associated in the region with choroidal angiopathy. In females, choroidal vessels slightly raised the pigment epithelial layer; however, they were localized in the choroid. The present study indicates that the WBN/Kob strain of rats is a useful model for both diabetic retinopathy and diabetic choroidal angiopathy.
Collapse
Affiliation(s)
- Naho Tsuji
- Department of Pathology, Faculty of Pharmaceutical Sciences, Setsunan University, Hirakata, Osaka, Japan
| | | | | | | | | |
Collapse
|
15
|
|
16
|
Spadella CT, Machado JLM, Lerco MM, Ortolan EVP, Schellini SA, Gregório EA. Temporal relationship between successful pancreas transplantation and control of ocular complications in alloxan-induced diabetic rats. Transplant Proc 2008; 40:518-23. [PMID: 18374119 DOI: 10.1016/j.transproceed.2008.01.049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
PURPOSE The impact of pancreas transplantation (PT) on the progression of eye disease is still controversial. This study evaluated the course of retinopathy in transplanted rats in two different diabetic stages. METHODS Sixty inbred male Lewis rats were assigned to four experimental groups: NC-15 nondiabetic control rats; DC-15 untreated diabetic control rats; PT1-15 diabetic rats that received syngeneic pancreas transplants 2 weeks after alloxan diabetes induction; PT2-15 diabetic rats that received pancreas transplants 12 weeks after diabetes onset. Clinical and laboratory parameters and lens opacity were examined in all rats prior to treatment and at 1-, 6-, and 12-months follow-up. Nucleated eyes from five rats in each group processed for ultrastructural study of the retinal at 6 and 12 months after PT or at follow-up. RESULTS Cataracts were observed in 20%, 60%, and 100% of DC rats at 1-, 6-, and 12-months follow-up, respectively. Early PT (2 weeks) significantly reduced the prevalence of this complication but not late (12 weeks) PT. PT1 rats also showed improved ultrastructure of the superficial and deep capillary plexuses of the retina, and of Müller cells, compared with DC and PT2. In the last group, retinopathy continued to evolve despite successful PT. CONCLUSION Our results suggested that prevention of diabetic ocular lesions by PT was closely dependent on earlier performance of the procedure.
Collapse
Affiliation(s)
- C T Spadella
- Department of Surgery, Botucatu School of Medicine, São Paulo State University (Unesp), Botucatu, SP, Brazil.
| | | | | | | | | | | |
Collapse
|
17
|
Shakoor A, Gupta M, Blair N, Shahidi M. Chorioretinal vascular oxygen tension in spontaneously breathing anesthetized rats. Ophthalmic Res 2007; 39:103-7. [PMID: 17284937 PMCID: PMC2883832 DOI: 10.1159/000099246] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Accepted: 10/19/2006] [Indexed: 11/19/2022]
Abstract
PURPOSE To establish baseline and variability of oxygen tension (PO(2)) measurements in the choroid, retinal arteries, capillaries, and veins of spontaneously breathing anesthetized rats and determine the effect of a moderate surgical procedure on the chorioretinal PO(2). METHODS Our previously established optical section phosphorescence imaging technique was utilized to measure PO(2) in the chorioretinal vasculatures. Imaging was performed in 29 spontaneously breathing rats under ketamine/xylazine anesthesia. In 7 rats, blood was drawn using a surgically implanted femoral arterial catheter and analyzed to determine the systemic arterial PO(2). The PO(2) measurements in 22 rats without surgery (group 1) and 7 surgically instrumented rats (group 2) were statistically compared. The intrasubject variability was calculated by the average standard deviation (SD) of repeated measurements. RESULTS The average systemic arterial PO(2) was 52 +/- 7 mm Hg (mean +/- SD) in group 2. In group 1, the average PO(2) measurements in the choroid, retinal arteries, capillaries, and veins were 50 +/- 11, 40 +/- 5, 39 +/- 6, and 30 +/- 5 mm Hg, respectively. No statistically significant PO(2) differences in any of the chorioretinal vasculatures were found between the two groups (p > 0.4). The intrasubject variability was 3 mm Hg in the choroid, retinal arteries, capillaries, and veins. CONCLUSIONS Chorioretinal PO(2) measurements in spontaneously breathing anesthetized rats have a relatively low variability, indicating that PO(2) changes due to various physiological alterations can be reliably assessed.
Collapse
Affiliation(s)
| | | | | | - M. Shahidi
- *Mahnaz Shahidi, PhD, Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, 1855 West Taylor Street, Chicago IL 60612 (USA), Tel. +1 312 413 7364, Fax +1 312 413 7366, E-Mail
| |
Collapse
|
18
|
Kakehashi A, Saito Y, Mori K, Sugi N, Ono R, Yamagami H, Shinohara M, Tamemoto H, Ishikawa SE, Kawakami M, Kanazawa Y. Characteristics of diabetic retinopathy in SDT rats. Diabetes Metab Res Rev 2006; 22:455-61. [PMID: 16572493 DOI: 10.1002/dmrr.638] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND We previously reported a new diabetic strain of the Sprague-Dawley rat, named the Spontaneously Diabetic Torii (SDT) rat. The purpose of the present study was to report the histologic and ultrastructural characteristics of diabetic retinopathy (DR) in a new animal model, the SDT rat. METHODS Fifty-three eyes of 43 SDT rats of various ages (35-82 weeks) were examined, of which 33 underwent histopathologic examination, 15 eyes fluorescein-dextran microscopy, and five eyes the trypsin digestion method. RESULTS Of the 33 eyes examined histopathologically, DR was identified in 20 eyes (61%). Large retinal folds mimicking diabetic tractional retinal detachment were observed in 20 eyes (61%). Retinal hemorrhages were seen in four eyes (12%). A neovascular fibrous membrane around the iris developed in five eyes (15%), of which two eyes had a massive anterior chamber hemorrhage. Of the 15 eyes examined by fluorescein-dextran microscopy, an area of nonperfusion and/or extensive hyperfluorescence was observed in 12 eyes (80%). Of the five eyes examined using the trypsin digestion method, acellular capillaries and pericyte loss were observed in four eyes (80%). Of the 53 eyes, the previously mentioned retinal changes of DR were observed in 36 eyes (68%). The rats with DR (49-82 weeks; mean, 60 weeks) were older than the rats without DR (35-55 weeks; mean, 40 weeks) (p < 0.001). CONCLUSION Large retinal folds mimicking tractional retinal detachment with extensive leakage of fluorescein around the optic disk was the most prominent finding of DR in SDT rats.
Collapse
Affiliation(s)
- Akihiro Kakehashi
- The Department of Ophthalmology, Omiya Medical Center, Jichi Medical University, Saitama 330-8503, Japan.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Matsuoka M, Ogata N, Minamino K, Higuchi A, Matsumura M. High levels of pigment epithelium-derived factor in the retina of a rat model of type 2 diabetes. Exp Eye Res 2006; 82:172-8. [PMID: 16054135 DOI: 10.1016/j.exer.2005.05.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2004] [Revised: 05/08/2005] [Accepted: 05/28/2005] [Indexed: 11/20/2022]
Abstract
Spontaneously diabetic Torii (SDT) rats are a new animal model of diabetes. To investigate the mechanisms controlling diabetic retinopathy, we examined the retinal changes in SDT rats and determined the molecular balance between pigment epithelium-derived factor (PEDF), an angiogenic inhibitor, and vascular endothelial growth factor (VEGF), a major angiogenic stimulator. The retinopathy in SDT rats was characterized by a low incidence of neovascular formation and absence of non-perfused areas, and high levels of both PEDF and VEGF. Proliferative neovascular membranes, that are similar to that in human eyes with proliferative diabetic retinopathy, were found in the eyes of some of the SDT rats at >50-weeks-of-age, Immunoreactivity for VEGF was detected in the retina of SDT rats and the level of VEGF increased with the duration of diabetes. More importantly, immunoreactivity for PEDF was also increased in the retina of diabetic SDT rats. Western blot analysis showed that the level of VEGF in the retina was increased by 2.4 fold at 20-week-old, and by 6.8 fold at >40-week-old compared to that of 10-weeks old SDT rats. The levels of PEDF in the retina at 20-week- and at >40-week-old were significantly higher than that of 10-weeks old SDT rats (20-week-old; 13.5-fold increase, > 40-week-old; 10.3-fold increase). Earlier studies showed that the level of PEDF was decreased and VEGF was increased in proliferative diabetic retinopathy in human eyes. The high levels of PEDF in the retina of SDT rats may contribute to the low incidence of neovascular formation and absence of non-perfused areas that do not match the typical diabetic retinopathy in humans.
Collapse
Affiliation(s)
- Masato Matsuoka
- Department of Ophthalmology, Kansai Medical University, Fumizono-cho 10-15, Moriguchi, Osaka 570-8507, Japan
| | | | | | | | | |
Collapse
|
20
|
Sun W, Gerhardinger C, Dagher Z, Hoehn T, Lorenzi M. Aspirin at low-intermediate concentrations protects retinal vessels in experimental diabetic retinopathy through non-platelet-mediated effects. Diabetes 2005; 54:3418-26. [PMID: 16306357 DOI: 10.2337/diabetes.54.12.3418] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The prevention of diabetic retinopathy requires drugs that leverage the benefits of glycemic control without adding the burden of side effects. Aspirin at dosages of 1-1.5 g/day has prevented manifestations of diabetic retinal microangiopathy in a clinical trial as well as in studies with dogs. Because lower and safer doses of aspirin could be used if its beneficial effects on retinopathy were due to antithrombotic effects, we compared the effects of a selective antiplatelet drug (clopidogrel) to those of aspirin in streptozotocin-induced diabetic rats. Clopidogrel did not prevent neuronal apoptosis, glial reactivity, capillary cell apoptosis, or acellular capillaries in the retina of diabetic rats. Aspirin, at doses yielding serum levels (<0.6 mmol/l) well below the anti-inflammatory range for humans, prevented apoptosis of capillary cells and the development of acellular capillaries but did not prevent neuroglial abnormalities. The aldose reductase inhibitor sorbinil, used as the benchmark for the effect of the other drugs, prevented all abnormalities. The diabetic rat retina showed increased expression of the transcription factor CCAAT/enhancer-binding protein-beta, one of the known targets of low-intermediate concentrations of aspirin. Thus we found a spectrum of drug efficacy on the prevention of experimental diabetic retinopathy, ranging from the absent effect of a selective antiplatelet drug to the prevention of all abnormalities by an aldose reductase inhibitor. Aspirin at low-intermediate concentrations selectively prevented microangiopathy. The minimal effective dose of aspirin should now be sought.
Collapse
Affiliation(s)
- Wei Sun
- Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, 20 Staniford St., Boston, Massachusetts 02114, USA
| | | | | | | | | |
Collapse
|
21
|
Yamada H, Yamada E, Higuchi A, Matsumura M. Retinal neovascularisation without ischaemia in the spontaneously diabetic Torii rat. Diabetologia 2005; 48:1663-8. [PMID: 15977012 DOI: 10.1007/s00125-005-1809-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2004] [Accepted: 02/28/2005] [Indexed: 02/03/2023]
Abstract
AIMS/HYPOTHESIS The spontaneously diabetic Torii (SDT) rat has recently been established as a model of type 2 human diabetes mellitus. Male SDT rats develop severe diabetic ocular complications. This study investigated the nature of the ocular complications in this model and addressed the question of whether the SDT rat is a good model of human proliferative diabetic retinopathy. METHODS Male SDT rats aged 50 weeks were studied for a period of 8 months. Under deep anaesthesia, one eye of each animal was enucleated following perfusion with fluorescein dextran and a retinal flat mount was prepared to study vascular structure. The other eye was enucleated and investigated histologically by haematoxylin-eosin and azan staining and by immunohistochemistry using antibodies against vascular endothelium (Griffonia simplicifolia isolectin B4 antibody) and vascular endothelial growth factor (VEGF). RESULTS From the vascular structure study, 17 of 32 rats (53%) showed proliferative retinopathy without vascular non-perfusion. The histological study revealed traction retinal folds in rats with proliferative retinopathy. Azan staining showed some proliferative matrix in rats with normal retinal structure and those with proliferative retinopathy compared with normoglycaemic controls. Staining with Griffonia simplicifolia isolectin B4 antibody showed no specific vascular changes in any of the rats, while VEGF staining revealed higher immunoreactivity in the retina of rats with normal retinal structure and those with proliferative retinopathy, but only low immunoreactivity in the control animals. CONCLUSIONS/INTERPRETATION There appear to be differences between the SDT rat model of diabetic retinopathy and human proliferative diabetic retinopathy, as the SDT rat develops retinal neovascularisation without retinal ischaemia. This very unique display of ocular neovascularisation may be caused by increased expression of VEGF.
Collapse
Affiliation(s)
- H Yamada
- Department of Ophthalmology, Kansai Medical University, Moriguchi, Osaka, Japan 570-8507.
| | | | | | | |
Collapse
|
22
|
Abstract
Patients with diabetes mellitus (DM) have accelerated atherothrombotic disease of coronary, cerebral, leg, and other vessels. The major cause of death is cardiovascular, and the risk for a myocardial infarction (MI) in a patient with DM who has never had a MI is the same as a nondiabetic individual who has already had one. In this paper, we review the major reasons for a prothrombotic state in patients with DM: alterations in the intrinsic coagulation and fibrinolytic systems and many abnormalities of platelet function. Increased platelet thromboxane production as well as activation of platelet receptors for fibrinogen and or adenosine diphosphate (ADP) are often present, and can be treated with aspirin (acetylsalicylic acid) and/or receptor blockers. Review of the major primary prevention trials in DM indicates that a significantly reduced risk for MI or major cardiovascular events may be obtained by enteric-coated aspirin, 81-325 mg/day. There is emerging consensus that this is recommended strategy in adult (aged >30 years) patients with DM who are at high vascular risk. Surveys suggest that this includes virtually every patient with type 2 DM in the US, as well as many patients with complicated type 1 DM. These recommendations are also appropriate for secondary prevention. Data supporting the use of clopidogrel as an alternative drug in the case of aspirin allergy or other contraindications are reviewed. Evidence is presented in support of using aspirin plus clopidogrel in acute coronary syndromes (ACS), and a meta-analysis of six trials of platelet glycoprotein (GP) IIb/IIIa inhibitors and aspirin in diabetic patients with ACS establishes this regimen as an effective choice. Although bleeding episodes are more common with combined antiplatelet therapy for ACS than for aspirin alone, the benefit of a significant reduction in 30-day mortality appears to outweigh the risk of major bleeding. It is concluded that major advances in our understanding of the prothrombotic state in DM have been made. Evidence from controlled clinical trials supports the use of enteric-coated aspirin, 81-325 mg/day, as a primary and a secondary prevention strategy in adults with DM with high vascular risk. In ACS, combination therapy with aspirin plus clopidogrel or alternatively, aspirin plus a platelet GP IIb/IIIa inhibitor is supported by prospective trial data. These approaches should be added to the other multifactorial preventive strategies directed at lowering the risk for major vascular events in patients with DM.
Collapse
Affiliation(s)
- John A Colwell
- Medical University of South Carolina, Charleston, South Carolina, USA
| |
Collapse
|
23
|
Rakoczy PE, Brankov M, Fonceca A, Zaknich T, Rae BC, Lai CM. Enhanced recombinant adeno-associated virus-mediated vascular endothelial growth factor expression in the adult mouse retina: a potential model for diabetic retinopathy. Diabetes 2003; 52:857-63. [PMID: 12606531 DOI: 10.2337/diabetes.52.3.857] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Diabetic retinopathy, one of the most serious complications of long-term diabetes, could clinically be divided into two stages: 1) background retinopathy that does not cause visual impairment and 2) proliferative retinopathy, which is a potentially blinding condition. This study aims to investigate the correlation between enhancement of vascular endothelial growth factor (VEGF) expression and neovascular changes. A binary recombinant adeno-associated virus construct producing green fluorescent protein (GFP) and VEGF under the control of the human cytomegalovirus promoter, recombinant adeno-associated virus (rAAV).VEGF.GFP, was produced and injected into the subretinal space of C57BL mice. GFP expression was tracked by fluorescence fundus photography, and VEGF expression was confirmed by immunohistochemistry and enzyme-linked immunoassay. Neovascular changes were monitored by fluorescein angiography and histology and by quantifying the number of inner retinal vessels. GFP expression was found in 100% of injected eyes, and vascular changes were detected in 9 of 10 rAAV.VEGF.GFP-injected eyes. Of these, four demonstrated microaneurysms and five showed moderate to severe leakage. There was a statistically significant increase in blood vessel number in the inner nuclear layer (P < 0.03) and dilatation of retinal veins (P < or = 0.05). This work has demonstrated that the development of different stages of diabetic retinopathy is closely correlated with an increased VEGF level in the retina.
Collapse
Affiliation(s)
- P Elizabeth Rakoczy
- Centre of Ophthalmology and Visual Science, the University of Western Australia, 2 Verdun Street, Nedlands, 6009 WA, Australia.
| | | | | | | | | | | |
Collapse
|
24
|
Davis GE, Bayless KJ, Mavila A. Molecular basis of endothelial cell morphogenesis in three-dimensional extracellular matrices. THE ANATOMICAL RECORD 2002; 268:252-75. [PMID: 12382323 DOI: 10.1002/ar.10159] [Citation(s) in RCA: 204] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Although many studies have focused on blood vessel development and new blood vessel formation associated with disease processes, the question of how endothelial cells (ECs) assemble into tubes in three dimensions (i.e., EC morphogenesis) remains unanswered. EC morphogenesis is particularly dependent on a signaling axis involving the extracellular matrix (ECM), integrins, and the cytoskeleton, which regulates EC shape changes and signals the pathways necessary for tube formation. Recent studies reveal that genes regulating this matrix-integrin-cytoskeletal (MIC) signaling axis are differentially expressed during EC morphogenesis. The Rho GTPases represent an important class of molecules involved in these events. Cdc42 and Rac1 are required for the process of EC intracellular vacuole formation and coalescence that regulates EC lumen formation in three-dimensional (3D) extracellular matrices, while RhoA appears to stabilize capillary tube networks. Once EC tube networks are established, supporting cells, such as pericytes, are recruited to further stabilize these networks, perhaps by regulating EC basement membrane matrix assembly. Furthermore, we consider recent work showing that EC morphogenesis is balanced by a tendency for newly formed tubes to regress. This morphogenesis-regression balance is controlled by differential gene expression of such molecules as VEGF, angiopoietin-2, and PAI-1, as well as a plasmin- and matrix metalloproteinase-dependent mechanism that induces tube regression through degradation of ECM scaffolds that support EC-lined tubes. It is our hope that this review will stimulate increased interest and effort focused on the basic mechanisms regulating capillary tube formation and regression in 3D extracellular matrices.
Collapse
Affiliation(s)
- George E Davis
- Department of Pathology, Texas A&M University System Health Science Center, College Station 77843, USA.
| | | | | |
Collapse
|
25
|
Li Q, Zemel E, Miller B, Perlman I. Early retinal damage in experimental diabetes: electroretinographical and morphological observations. Exp Eye Res 2002; 74:615-25. [PMID: 12076083 DOI: 10.1006/exer.2002.1170] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A growing body of evidence indicates that impairment of retinal function precedes the earliest signs of vascular complications. The aim of this study was to follow the development of retinopathy both functionally and morphologically in a rat model of diabetes mellitus. Diabetes was induced in rats by intravenous injection of streptozotocin (STZ). Age-matched rats raised under similar conditions served as control. The electroretinogram (ERG) was recorded in order to assess retinal function. The expression of glial fibrillary acidic protein (GFAP) in Müller cells was used as a cellular marker for retinal damage. The ERG responses of the diabetic rats were reduced in amplitude compared to the responses recorded from the control rats as early as 2 weeks after onset of diabetes. The b-wave was more affected than the a-wave. GFAP expression in the diabetic retina did not differ from that in the control retina during the first 5 weeks of diabetes. GFAP was demonstrated only in astrocytes in the vitreo-retinal border. After 6-7 weeks of diabetes, GFAP expression in the retinas of the diabetic rats was also detected in the endfeet of the Müller cells. With the progression of diabetes, GFAP expression spreads throughout the entire length of the Müller cells. In the retinas from control rats, GFAP expression was limited to astrocytes and was not detected in Müller cells even at 40 weeks of follow-up. The observations indicate that the functional integrity of retinal cells is compromised already at short time intervals after onset of experimental diabetes in rats.
Collapse
Affiliation(s)
- Q Li
- Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology and Rappaport Institute, Haifa, Israel
| | | | | | | |
Collapse
|
26
|
Abstract
In diabetic retinopathy, capillary nonperfusion and eventual obliteration can lead to retinal ischemia and sight-threatening neovascularization. The occurrence of retinal microthrombosis in human diabetes has long been suspected and occasionally observed but never systematically demonstrated. We used trypsin digestion to isolate the intact vascular network from retinas obtained postmortem from nine diabetic donors (age 64 +/- 11 years, duration of diabetes 6 +/- 4 years; mean +/- SD) and eight age-matched nondiabetic donors. Topographically matched sectors (each one-sixth of retina) of diabetic and nondiabetic retinas were tested sequentially with antibodies to fibrin cross-linking factor XIII and platelet glycoprotein (GP)-IIIa to identify fibrin-platelet thrombi. In some trypsin digests, we also examined vascular cell apoptosis. The retina from a nondiabetic donor, 24 years of age, who had died of trauma, was used to exclude confounding influences caused by the postmortem period. When compared with those of nondiabetic donors, the retinas of diabetic donors showed double the number of capillary segments with colocalized immunostaining for factor XIII and GPIIIa (P = 0.02). The total area of the positive segments was fourfold greater in the diabetic than in the nondiabetic donors (P = 0.02) and correlated with the duration of diabetes (r = 0.71, P < 0.05). Large thrombi were six times more frequent in the diabetic donors (P = 0.03), and there was a significant topographical association of microthrombosis with apoptotic cells in both diabetic and nondiabetic vessels (P = 0.0001). Hence, diabetes of short duration was found to be associated with a greater than normal number and size of platelet-fibrin thrombi in the retinal capillaries. These thrombi can contribute to capillary obliteration and retinal ischemia and may be a practical target for early drug intervention.
Collapse
Affiliation(s)
- D Boeri
- Schepens Eye Research Institute, 20 Staniford Street, Boston, MA 02114, USA
| | | | | |
Collapse
|
27
|
Chakrabarti S, Sima AA. Endothelin-1 and endothelin-3-like immunoreactivity in the eyes of diabetic and non-diabetic BB/W rats. Diabetes Res Clin Pract 1997; 37:109-20. [PMID: 9279481 DOI: 10.1016/s0168-8227(97)00057-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Endothelins (ETs) are a family of vasoactive peptides implicated in several disorders of the microvasculature. In the present study, the distribution of immunoreactive ET-1 and ET-3 was investigated in eyes from 8 month spontaneously diabetic BB/W rats and in age matched control animals. Both peptides showed similar immunoreactivity. In non-diabetic animals, corneal epithelium and endothelium, ciliary epithelium, lens epithelium, iris and the microvasculature of the sclera and choroid showed positive immunoreactivity. In the retina, photoreceptor inner segments showed positivity. In the inner nuclear layer, cells of both neuronal and glial origins showed positive immunoreactivity. Both the nuclei and the cytoplasm of the ganglion cells were positively stained. Retinal pigment epithelium showed patchy but consistent immunoreactivity. Capillary endothelial cells showed inconsistent positive staining. The pericytes were uniformly negative. In diabetic animals although overall intensity was increased, retinal pigment epithelium and ciliary epithelium showed no immunoreactivity. The corneal epithelium showed increased but patchy immunoreactivity. The altered intensity and distribution of ETs in diabetes suggest that ETs may be of importance in the pathogenesis of chronic occular complications in the diabetic BB/W rat.
Collapse
Affiliation(s)
- S Chakrabarti
- Department of Pathology, University of Western Ontario, London, Canada.
| | | |
Collapse
|
28
|
Zhang H, Agardh CD, Agardh E. Retinal nitro blue tetrazolium staining and catalase activity in rat models of diabetes. Graefes Arch Clin Exp Ophthalmol 1996; 234:324-30. [PMID: 8740254 DOI: 10.1007/bf00220708] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Recent studies have suggested that reactive oxygen species may be involved in the development of diabetic retinopathy. METHODS Nitro blue tetrazolium (NBT) staining, a marker of reductants which may be induced by free radicals such as superoxide, and catalase activity, as an indirect measure of hydrogen peroxide (H2O2) generation, were studied in the rat retina in three conditions known to cause diabetes-like retinopathy, i.e. rats with spontaneous diabetes (the BB Wistar rat), rats with streptozotocin-induced diabetes mellitus, and rats fed on galactose. Male Wistar BB rats were studied 4-10 weeks after diagnosis of diabetes. Streptozotocin (60 mg/kg) was injected i.p. at 8 weeks of age and the experiments were performed after 8 weeks of diabetes. Young Sprague-Dawley rats were fed a 50% galactose diet for 9, 12 or 22 months. RESULTS In trypsinized vessel preparations, more intense NBT staining was observed only in rats fed a galactose diet for 22 months. In cross sections, the number of stained vessels were increased in BB rats (p < 0.01), but not in rats with streptozotocin-induced diabetes. Catalase activity did not differ between any of the experimental groups and their matched controls. CONCLUSIONS Increased amount of NBT reductants in retinal vessels occurred in BB Wistar rats and to some extent in galactose-fed rats, indicating a possible role for free radicals in the development of diabetic retinopathy. There was no evidence of increased retinal H2O2 production or activation of catalase, indicating that this particular enzyme was not affected during the conditions studied.
Collapse
Affiliation(s)
- H Zhang
- Department of Ophthalmology, University Hospital, Lund, Sweden
| | | | | |
Collapse
|
29
|
Yagihashi S. Pathology and pathogenetic mechanisms of diabetic neuropathy. DIABETES/METABOLISM REVIEWS 1995; 11:193-225. [PMID: 8536541 DOI: 10.1002/dmr.5610110304] [Citation(s) in RCA: 113] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- S Yagihashi
- Department of Pathology, Hirosaki University School of Medicine, Japan
| |
Collapse
|
30
|
Robinson W, Laver NM, Lou MF. The role of aldose reductase in diabetic retinopathy: Prevention and intervention studies. Prog Retin Eye Res 1995. [DOI: 10.1016/1350-9462(94)00020-g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
31
|
Wadhwani KC, Rapoport SI. Transport properties of vertebrate blood-nerve barrier: comparison with blood-brain barrier. Prog Neurobiol 1994; 43:235-79. [PMID: 7816928 DOI: 10.1016/0301-0082(94)90002-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- K C Wadhwani
- Laboratory of Neurosciences, NIA, NIH, Bethesda, MD 20892
| | | |
Collapse
|
32
|
Abstract
The morphology of the vitreoretinal border region, also termed the inner limiting membrane, was examined in spontaneously diabetic rats (BB rats), in non-diabetes-prone rats (WB rats) and in Buffalo rats (BUF rats) by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). This was performed in order to visualize a possible increase in thickness of the lamina densa or in the whole vitreoretinal border region complex with duration of diabetes. The median thickness of the lamina densa in the three groups varied between 34 and 68 nm. In BB rats the thickness decreased with age and duration of diabetes. In WB rats the lamina densa thickened up to the 9th month and then decreased to the level of the young rats. In BUF rats the lamina densa decreased in thickness with age. The median thickness of the whole vitreoretinal border region varied between: BB rats: 84 and 126 nm (SEM) and 68 and 119 nm (TEM); WB rats: 42 and 84 nm (SEM) and 51 and 68 nm (TEM); BUF rats: 42 nm (SEM) and 34 and 68 nm (TEM). In BB rats the whole vitreoretinal border region appeared in SEM to thicken with duration of diabetes > or = 27 weeks, whereas in TEM no specific pattern could be statistically demonstrated. In WB rats the whole vitreoretinal border region was thinner in 3-month-old animals than in 9-month-old animals in (SEM) and TEM. In BUF rats there was no difference in thickness between young and older animals. Light microscopy of older diabetic animals showed neovascularization of the iris stroma.
Collapse
Affiliation(s)
- S Heegaard
- Eye Pathology Institute, University of Copenhagen, Denmark
| |
Collapse
|
33
|
Chakrabarti S, Cherian PV, Sima AA. The effect of acarbose on diabetes- and age-related basement membrane thickening in retinal capillaries of the BB/W-rat. Diabetes Res Clin Pract 1993; 20:123-8. [PMID: 8375264 DOI: 10.1016/0168-8227(93)90005-p] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The effect of the alpha-glucosidase inhibitor acarbose on retinal capillary basement membrane thickening was examined in the spontaneously diabetic BB/W-rat. Four months of diabetes resulted in significant thickening of the basement membranes of both the superficial and deep capillary nets of the retina. This characteristic change of the retinal microvasculature in diabetes was completely prevented by acarbose treatment that substantially reduced postprandial hyperglycemia. A similar but less pronounced effect was seen on the age-related increase in basement membrane thickening in acarbose-treated non-diabetic control rats who demonstrated decreased glycated hemoglobin levels compared to non-treated control rats. Significant positive correlations between basement membrane thickness and glycated hemoglobin area suggest that diabetic retinal microangiopathy may be prevented by lowering the cumulative glucose exposure to the microvasculature, and that age-related basement membrane thickening is mediated by long-term exposure to normal glucose levels.
Collapse
Affiliation(s)
- S Chakrabarti
- Department of Pathology, University of Manitoba, Winnipeg, Canada
| | | | | |
Collapse
|
34
|
Affiliation(s)
- D R Tomlinson
- Department of Pharmacology, Queen Mary and Westfield College, London, UK
| |
Collapse
|
35
|
Guberski DL. Diabetes-Prone and Diabetes-Resistant BB Rats: Animal Models of Spontaneous and Virally Induced Diabetes Mellitus, Lymphocytic Thyroiditis, and Collagen-Induced Arthritis. ILAR J 1993. [DOI: 10.1093/ilar.35.2.29] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
|
36
|
Nehls V, Drenckhahn D. The versatility of microvascular pericytes: from mesenchyme to smooth muscle? HISTOCHEMISTRY 1993; 99:1-12. [PMID: 8468190 DOI: 10.1007/bf00268014] [Citation(s) in RCA: 165] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- V Nehls
- Department of Anatomy, Julius-Maximilians-University, Würzburg, Germany
| | | |
Collapse
|
37
|
Murray FT, Johnson RD, Sciadini M, Katovich MJ, Rountree J, Jewett H. Erectile and copulatory dysfunction in chronically diabetic BB/WOR rats. THE AMERICAN JOURNAL OF PHYSIOLOGY 1992; 263:E151-7. [PMID: 1636693 DOI: 10.1152/ajpendo.1992.263.1.e151] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The pituitary-testicular axis, penile reflexes, and copulatory behavior were studied in male BB diabetic rats from 10 to 40 wk of diabetes. Serum testosterone was diminished from 18 to 28 wk of diabetes, and the responses to human chorionic gonadotropin stimulation were blunted. Serum luteinizing hormone (LH) in diabetic rats did not differ from that of the control rats before or after LH-releasing hormone stimulation. Serum follicle-stimulating hormone and prolactin levels were also similar to controls. After 26 wk of diabetes, androgen-sensitive reproductive accessory organs were significantly reduced in size. This also was true for the androgen-sensitive bulbocavernosus and ischiocavernosus muscles. Penile reflexes in these animals from 20 to 32 wk of diabetes were consistently reduced in number and demonstrated prolonged latency. Copulatory behavior was evaluated in these animals at 25 and 28 wk of diabetes and revealed a reduced number of BB diabetic rats showing normal behavior at 25 wk of diabetes. At 28 wk of diabetes, mount latency, intromission latency, ejaculatory latency, and the postejaculatory interval were all prolonged compared with controls. In addition, the number of diabetic animals showing normal behavior was reduced compared with controls. These studies demonstrate that chronically BB diabetic rats develop diminished testosterone and erectile dysfunction that precedes ejaculatory dysfunction in a similar fashion as impotence in diabetic men. We suggest that further studies in this animal model may be critical to the better understanding and treatment of impotence in diabetic men.
Collapse
Affiliation(s)
- F T Murray
- Department of Medicine, University of Florida, Gainesville 32610
| | | | | | | | | | | |
Collapse
|
38
|
|
39
|
Abstract
Aldose reductase inhibitors impede flux of glucose through the sorbitol pathway in diabetes mellitus. They therefore reduce the accumulation of the pathway metabolites, sorbitol and fructose, reduce the impact of the flux on the cofactors used by the pathway and reduce other derived phenomena, such as osmotic stress and myo-inositol depletion. As drugs, their targets are the chronic complications of diabetes--neuropathy, retinopathy, nephropathy and vasculopathy. In experimental models there is proof of activity against biochemical, functional and structural defects in all of the involved tissues, but we await full clinical verification of this potential.
Collapse
Affiliation(s)
- D R Tomlinson
- Department of Pharmacology, Queen Mary and Westfield College, London, U.K
| | | | | |
Collapse
|
40
|
Robison WG, McCaleb ML, Feld LG, Michaelis OE, Laver N, Mercandetti M, Robinson WG. Degenerated intramural pericytes ('ghost cells') in the retinal capillaries of diabetic rats. Curr Eye Res 1991; 10:339-50. [PMID: 1829996 DOI: 10.3109/02713689108996340] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
One of the earliest histopathological signs of diabetic retinopathy is a selective loss of intramural pericytes from retinal capillaries. In the present study, the retinal vessels of rats with streptozotocin-induced diabetes (STZ Wistar) and rats with genetically-induced insulin dependent diabetes mellitus (BB Wistar) and non-insulin dependent diabetes mellitus (SHR/N-corpulent) were examined after 6 to 8 months duration for diabetes-related retinal microangiopathies. The SHR/N-corpulent (cp) rats were fed a 54% sucrose diet, whereas the STZ Wistar and BB Wistar rats were fed laboratory chow for 32 to 36 weeks. In all the diabetic rats, the retinal capillaries in enzyme-digested flat mounts exhibited an increase in periodic-acid-Schiff (PAS) staining and loss of pericytes compared to their respective euglycemic controls. Pericyte "ghosts", like those defined in human diabetes as intramural pockets lacking normal cell contents, were documented by high resolution micrographs in all the diabetic rats. Endothelial cell proliferation, capillary dilation, and varicose loop formation were noted in some of the diabetic rats. Hence, similar capillary lesions were found in very different groups of diabetic rats. The findings suggest that a chronic high tissue concentration of glucose is the underlying factor which triggers pathogenesis in the pericyte. Hyperglycemia-induced activation of endogenous aldose reductase of the polyol pathway is probably the initial insult, but other factors such as advanced glycosylation products may affect the final outcome.
Collapse
|
41
|
Pugliese G, Tilton RG, Williamson JR. Glucose-induced metabolic imbalances in the pathogenesis of diabetic vascular disease. DIABETES/METABOLISM REVIEWS 1991; 7:35-59. [PMID: 1935535 DOI: 10.1002/dmr.5610070106] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- G Pugliese
- Department of Experimental Medicine, La Sapienza University, Policlinico Umberto 1, Rome, Italy
| | | | | |
Collapse
|
42
|
Cameron DF, Rountree J, Schultz RE, Repetta D, Murray FT. Sustained hyperglycemia results in testicular dysfunction and reduced fertility potential in BBWOR diabetic rats. THE AMERICAN JOURNAL OF PHYSIOLOGY 1990; 259:E881-9. [PMID: 2260654 DOI: 10.1152/ajpendo.1990.259.6.e881] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Rats with short-term diabetes show a greater than 50% reduction of serum testosterone and increased lipid in Leydig cells but normal testicular structure. The purpose of this study was to determine the extent of testicular pathology (morphology index), integrity of the blood-testis barrier, daily sperm production (DSP), number of Leydig cells per testis (LC/T), and total trunk testosterone (TTT) in diabetic rats (BBWORdp) with long-term hyperglycemia (300-350 mg/dl for greater than 180 days) and to evaluate its effects on fertility potential. Results were compared with similarly aged normoglycemic rats (BBWORdr) and normal control Wistar rats. After 6 mo of diabetes, testis weights, DSPs, TTTs, and the morphology index were significantly reduced. The LC/T was not different from BBWORdr rats. The blood-testis barrier appeared intact, although structural abnormalities were noted in Sertoli-Sertoli junction complexes. There was a significant reduction in the number of pregnancies per rat and implantations per pregnancy in matings utilizing the diabetic BBWORdp rat and control Wistar female rats. Results indicate that long-term diabetes with sustained hyperglycemia leads to significant testicular dysfunction associated with decreased fertility potential.
Collapse
Affiliation(s)
- D F Cameron
- Department of Anatomy, University of South Florida, Tampa 33612
| | | | | | | | | |
Collapse
|
43
|
Benstead TJ, Sangalang VE, Dyck PJ. Acute endothelial swelling is induced in endoneurial microvessels by ischemia. J Neurol Sci 1990; 99:37-49. [PMID: 2250170 DOI: 10.1016/0022-510x(90)90197-u] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Structural alterations of endoneurial microvessels occur in diabetic neuropathy and are statistically associated with severity of nerve fiber loss and teased fiber abnormality. It is therefore hypothesized that the microvessel alterations may cause or contribute to pathologic alterations of nerve fibers in diabetic neuropathy, possibly through hypoxic injury. The mechanism of the microvessel change in diabetic neuropathy is unknown. The role of microvessels and details of microvessel structure in other possible ischemic neuropathies has not been studied completely. Already there is evidence that hypoxia induces endothelial swelling but this has not been characterized or quantitated in nerve. To determine the acute morphologic effect of ischemia on ultrastructural features of transverse profiles of endoneurial microvessels major pelvic arteries were ligated in rats. At 36 h mean lumen and mural areas were greater in ischemic than in control nerves. All components (endothelium, pericytes and basement membrane) were on average greater in ischemic than controls. The greatest increase was in endothelial cells. In these cells swollen mitochondria were abundant. This study demonstrates that acute ischemia induces swelling of the cells and organelles of endoneurial microvessels.
Collapse
Affiliation(s)
- T J Benstead
- Department of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | | | | |
Collapse
|
44
|
Dosso A, Rungger-Brändle E, Rohner-Jeanrenaud F, Ionescu E, Guillaume-Gentil C, Jeanrenaud B, Leuenberger PM. Ocular complications in the old and glucose-intolerant genetically obese (fa/fa) rat. Diabetologia 1990; 33:137-44. [PMID: 2184064 DOI: 10.1007/bf00404039] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Genetically obese fatty (fa/fa) male rats with abnormal oral glucose tolerance associated with initial hyperinsulinaemia as well as control lean (FA/FA) rats were investigated for the development of retinal microangiopathies. The animals were kept on a standard or sucrose supplemented diet. When tested at 60 weeks, the glucose intolerance of fa/fa rats was accompanied by an insulin response that was now either comparable to that of lean rats (standard diet) or close to nil (sucrose supplemented diet). At killing (68 weeks of age), retinal vasculature was examined by electron microscopy and morphological changes were quantitatively assessed by ultrastructural morphometry. A retinal microangiopathy was observed in all mutant animals which was more pronounced in the sucrose fed group, and which was characterized by: (1), an increase in focal thickenings and in nodules of the basement membrane adjacent to the perivascular glial cells: (2), a decrease in the number of pericyte nulei with concomitant signs of early degenerative cytoplasmic changes of pericytes; (3), an increase in the pinocytic activity of endothelial cells, indicative of presumptive changes in vascular permeability; (4), an increase in the number of intercellular endothelial junctions; (5), the presence of numerous stimulated platelets within capillaries. The fa/fa rat may thus be considered as a suitable model for studying the pathophysiology of ocular complications, in particular retinopathy accompanying non-insulin-dependent diabetes.
Collapse
Affiliation(s)
- A Dosso
- Laboratoire de Microscopie électronique, Faculty of Medicine, Geneva, Switzerland
| | | | | | | | | | | | | |
Collapse
|
45
|
Fitzgerald ME, Caldwell RB. The retinal microvasculature of spontaneously diabetic BB rats: structure and luminal surface properties. Microvasc Res 1990; 39:15-27. [PMID: 2314305 DOI: 10.1016/0026-2862(90)90056-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Endothelial cell permeability and luminal surface anionic sites were studied in the retinal microvasculature of spontaneously diabetic rats. Horseradish peroxidase (HRP) was used as a tracer of pinocytotic transport, and cationized ferritin (CF) was used as a marker of luminal surface anionic sites. Diabetic and control rats were injected with HRP, and their retinas were fixed. Retinal tissue sections were then incubated in CF, reacted to visualize HRP, and prepared for quantitative electron microscopic analysis. In both control and diabetic rats treated with serotonin and histamine antagonists to prevent HRP-induced vascular changes, the endothelium formed a barrier to the tracer. Pinocytotic uptake was relatively low in most vessels. Reaction product was restricted to pinocytotic vesicles, tubular cisternae, and multivesticular bodies. HRP uptake appeared high in some of the deep capillaries of the diabetic retinas as compared with that of the controls, but the difference was not statistically significant. HRP-induced transendothelial permeability was observed in both control and diabetic rats when serotonin and histamine antagonist pretreatment was omitted. CF studies showed anionic sites in four luminal surface microdomains in control and diabetic endothelial cells. CF-binding, anionic sites were present on the plasma membrane, on all coated vesicles, on some uncoated vesicles, and on most diaphragms of uncoated vesicles. Plasma membrane binding was sparse and patchy in some diabetic vessels, especially in the deep vessels of rats that were not treated with the serotonin and histamine antagonists. However, statistical analysis showed similar numbers of plasma membrane binding sites in diabetic and control rats pretreated with serotonin and histamine antagonists. Our data suggest that the retinal microvasculature in diabetic rats remains normal in terms of permeability and luminal membrane anionic charge.
Collapse
Affiliation(s)
- M E Fitzgerald
- Department of Anatomy and Neurobiology, University of Tennessee, Memphis 38163
| | | |
Collapse
|
46
|
Vinores SA, Campochiaro PA. Prevention or moderation of some ultrastructural changes in the RPE and retina of galactosemic rats by aldose reductase inhibition. Exp Eye Res 1989; 49:495-510. [PMID: 2507341 DOI: 10.1016/0014-4835(89)90057-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Rats were maintained on a 50% galactose diet with and without the aldose reductase inhibitor, Sorbinil, or on a normal diet of rat chow, and the retinas and retinal pigment epithelium were examined ultrastructurally at time points ranging from 4 weeks to 20 months. Several ultrastructural changes were observed in the retinal pigment epithelium and retinal capillaries of galactosemic rats that were not seen in rats on a normal diet. Only some of these changes are similar to those that have been previously noted in diabetic (glucosemic) rats. As in diabetics, galactosemic rats demonstrated thickening of the basal laminae of the retinal pigment epithelium and retinal capillaries. They also manifested vacuolization and degenerative foci in the retinal pigment epithelium that were similar, but not identical, to changes seen in diabetic rats. Each of these changes was significantly inhibited by Sorbinil. Unlike diabetics, galactosemic rats did not have dilated basal infoldings, but did have outer retinal folds and a significant increase in large-lipofuscin-like aggregates in the retinal pigment epithelium, both of which were partly prevented by Sorbinil. These data suggest that multiple mechanisms may be involved in retinal and retinal pigment epithelium changes in diabetic and galactosemic rats, and that enhanced polyol metabolism is likely to be involved in some of the changes in both.
Collapse
Affiliation(s)
- S A Vinores
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville 22908
| | | |
Collapse
|
47
|
Fitzgerald ME, Caldwell RB. Lectin-ferritin binding on spontaneously diabetic and control rat retinal microvasculature. Curr Eye Res 1989; 8:271-83. [PMID: 2707043 DOI: 10.3109/02713688908997569] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We previously reported, in the spontaneously diabetic Bio-Breeding (BB) rat, an increase in horseradish peroxidase (HRP) uptake that was associated with reduction and patching of cationized ferritin (CF) binding to anionic sites on the luminal plasma membrane of the retinal capillary endothelium. To see whether alterations in the negatively charged terminal sugar residues, N-acetyl-glucosamine (NAG) and sialic acid (SA), might contribute to these changes in the diabetic rat retina, we used lectin-ferritin (Fe) conjugates to study the distribution of these sugars on the retinal endothelial luminal membranes. Wheat germ agglutin (WGA, binds to NAG and SA) and Limax flavius (LFA, binds only SA) were used. Plasma membrane WGA-Fe binding was dense and uniform in control animals. Binding sites were also found in coated luminal vesicles, within some uncoated luminal vesicles and on their diaphragms. Unlabeled uncoated luminal vesicles were also seen, suggesting two populations of uncoated vesicles. In diabetic animals, the binding sites were present within the same membrane associated microdomains as in the controls. However, in the majority of outer plexiform layer (OPL) vessels in diabetic animals, WGA-Fe binding was reduced to a single, discontinuous layer of particles (p less than 0.02). In both diabetic and control vessels, WGA-Fe binding was greatly reduced by the addition of competitive sugars. A few particles remained on the plasma membrane, on the diaphragms of some vesicles, and at the edge of vesicles. LFA-Fe binding was similar to that seen with WGA-Fe in the presence of competitive sugars. These results suggest that luminal membranes of retinal capillaries are rich in NAG and contain little SA. The sparse WGA-Fe binding pattern in the diabetic OPL may reflect decreases in number or accessibility of NAG residues, since similar binding patterns are seen in both the control and diabetic animals under conditions specific for SA. Thus, alteration of terminal NAG residues may contribute to decreased luminal surface anionic sites and increased pinocytotic transport in the retinal microvasculature of spontaneously diabetic BB rats.
Collapse
Affiliation(s)
- M E Fitzgerald
- Department of Anatomy and Neurobiology, University of Tennessee, Memphis 38163
| | | |
Collapse
|
48
|
Kwok CF, Goldstein BJ, Muller-Wieland D, Lee TS, Kahn CR, King GL. Identification of persistent defects in insulin receptor structure and function capillary endothelial cells from diabetic rats. J Clin Invest 1989; 83:127-36. [PMID: 2910904 PMCID: PMC303652 DOI: 10.1172/jci113848] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Insulin actions and receptors were studied in capillary endothelial cells cultured from diabetic BB rats and their nondiabetic colony mates. The endothelial cells from diabetic rats of 2 mo duration had persistent biological and biochemical defects in culture. Compared with normal rats, endothelial cells from diabetic rats grew 44% more slowly. Binding studies of insulin and insulin-like growth factor I (IGF-I) showed that cells from diabetic rats had 50% decrease of insulin receptor binding (nondiabetic: 4.6 +/- 0.7; diabetic: 2.6 +/- 0.4% per milligram protein, P less than 0.01), which was caused by a 50% decrease in the number of binding sites per milligram protein, whereas IGF-I binding was not changed. Insulin stimulation of 2-deoxy-glucose uptake and alpha-aminoisobutyric acid uptake were also severely impaired with a 80-90% decrease in maximal stimulation, in parallel with a 62% decrease in insulin-stimulated autophosphorylation (P less than 0.05). 125I-insulin cross-linking revealed an 140-kD alpha subunit of the insulin receptor similar to that in cells from nondiabetic rats, although bands at greater than 200 kD were also detected. The molecular weight of the insulin receptor beta subunit (by SDS-PAGE) was smaller in cells from diabetic than from normal rats (88-90 vs. 95 kD). Neuraminadase treatment of the partially purified insulin receptors decreased the molecular weight of the insulin receptors from nondiabetic rats to a greater degree than its diabetic counterpart. In contrast, Northern blot analysis of insulin receptor mRNAs using human cDNA probes revealed two species of 9.4 and 7.2 kb with no difference in mRNA abundance between cells from diabetic and nondiabetic rats. We conclude that the exposure of capillary endothelial cells to a diabetic milieu in vivo can cause specific and persistent changes in the insulin receptor and insulin action.
Collapse
Affiliation(s)
- C F Kwok
- Research Division, Joslin Diabetes Center, Boston, Massachusetts 02215
| | | | | | | | | | | |
Collapse
|
49
|
Affiliation(s)
- P F Kador
- National Eye Institute, Bethesda, Maryland 20892
| |
Collapse
|
50
|
Williamson JR, Tilton RG, Chang K, Kilo C. Basement membrane abnormalities in diabetes mellitus: relationship to clinical microangiopathy. DIABETES/METABOLISM REVIEWS 1988; 4:339-70. [PMID: 3292174 DOI: 10.1002/dmr.5610040404] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- J R Williamson
- Pathology Department, Washington University School of Medicine, St. Louis, Missouri 63110
| | | | | | | |
Collapse
|