title: Therapeutic efficacy of melatonin in reducing retinal damage in an experimental model of early type 2 diabetes in rats.
abstract: Diabetic retinopathy (DR) is a leading cause of acquired blindness in adults, mostly affected by type 2 diabetes mellitus (T2DM). We have developed an experimental model of early T2DM in adult rats which mimics some features of human T2DM at its initial stages and provokes significant retinal alterations. The aim of this work was to analyze the effect of melatonin on retinal changes induced by the moderate metabolic derangement. For this purpose, adult male Wistar rats received a control diet or 30% sucrose in the drinking water. Three weeks after this treatment, animals were injected with vehicle or streptozotocin (STZ, 25 mg/kg). One day or 3 wk after vehicle or STZ injection, animals were subcutaneously implanted with a pellet of melatonin. Fasting and postprandial glycemia, and glucose, and insulin tolerance tests were analyzed. At 12 wk of treatment, animals which received a sucrose-enriched diet and STZ showed significant differences in metabolic tests, as compared with control groups. Melatonin, which did not affect glucose metabolism in control or diabetic rats, prevented the decrease in the electroretinogram a-wave, b-wave, and oscillatory potential amplitude, and the increase in retinal lipid peroxidation, NOS activity, TNFα, Müller cells glial fibrillary acidic protein, and vascular endothelial growth factor levels. In addition, melatonin prevented the decrease in retinal catalase activity. These results indicate that melatonin protected the retina from the alterations observed in an experimental model of DR associated with type 2 diabetes.
authors.affiliation: Laboratory of Retinal Neurochemistry and Experimental Ophthalmology, Department of Human Biochemistry, School of Medicine/CEFyBO, University of Buenos Aires/CONICET, Buenos Aires, Argentina.
authors.forename: Ezequiel M
authors.initials: EM
authors.lastname: Salido
authors.forename: Melina
authors.initials: M
authors.lastname: Bordone
authors.forename: Andrea
authors.initials: A
authors.lastname: De Laurentiis
authors.forename: Mónica
authors.initials: M
authors.lastname: Chianelli
authors.forename: María Inés
authors.initials: MI
authors.lastname: Keller Sarmiento
authors.forename: Damián
authors.initials: D
authors.lastname: Dorfman
authors.forename: Ruth E
authors.initials: RE
authors.lastname: Rosenstein
mesh_terms: D000818:Animals; D002374:Catalase / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000378:metabolism*; D003930:Diabetic Retinopathy / Q000188:drug therapy* / Q000378:metabolism*; D004596:Electroretinography; D005947:Glucose / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D008550:Melatonin / Q000627:therapeutic use*; D051381:Rats; D017208:Rats, Wistar; D013858:Thiobarbiturates / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D013858:Thiobarbiturates; D014409:Tumor Necrosis Factor-alpha; D002374:Catalase; D005947:Glucose; D008550:Melatonin; C029684:thiobarbituric acid