Exogenous SOD Mimetic Tempol Ameliorates the Early Retinal Changes Reestablishing the Redox Status in Diabetic Hypertensive Rats

Autor(es)

Rosales, Mariana A. B. ^[1] ; Silva, Kamila C. ^[1] ; Lopes de Faria, Jose B. ^[1] ; Lopes de Faria, Jacqueline M. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas, Fac Med Sci, Renal Pathophysiol Lab, Dept Internal Med, Campinas, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE; v. 51, n. 8, p. 4327-4336, AUG 2010.
• Citações Web of Science: 25

Resumo

PURPOSE. The purpose of this study was to investigate the efficacy of tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl), a superoxide dismutase mimetic, in preventing early retinal molecular changes in a model that combines hypertension and diabetes. METHODS. Four-week-old spontaneously hypertensive rats (SHR) were rendered diabetic by streptozotocin. Diabetic SHR rats (DM-SHR) were randomized to receive or not receive tempol treatment. After 20 days of induction of diabetes, the rats were euthanatized, and their retinas were collected. RESULTS. The early molecular markers of diabetic retinopathy (DR), glial fibrillary acidic protein, and fibronectin were evaluated by Western blot assays and showed an increase in DM-SHR compared with the SHR group. The oxidative balance, evaluated by superoxide production and nitric oxide end product levels estimated by a nitric oxide analyzer, and the counterpart antioxidative defense revealed an accentuated imbalance in DM-SHR compared with the SHR group. As a result, the product peroxynitrite, which was detected by immunohistochemistry for nitrotyrosine, was higher in the DM-SHR group. The retinal poly-ADP-ribose (PAR)-modified proteins, which reflect the activation of PAR polymerase (PARP), and the inducible nitric oxide synthase (iNOS) expressions were found to have increased in this group. Treatment with tempol reestablished the oxidative parameters and decreased the PAR-modified proteins, thus preventing extracellular matrix accumulation and glial reaction. CONCLUSIONS. The administration of tempol prevented oxidative damage, decreased iNOS levels, and ameliorated the activation of PARP in the retinas of diabetic hypertensive rats. Consequently, the early molecular markers of DR, such as glial reaction (glial fibrillary acidic protein {[}GFAP]) and extracellular matrix accumulation (fibronectin), were prevented in tempol-treated rats. (Invest Ophthalmol Vis Sci. 2010; 51:4327-4336) DOI:10.1167/iovs.09-4690 (AU)

• Processo FAPESP: 05/58189-5 - A hipertensão arterial acentua a neurodegeneração retiniana na patogênese da retinopatia diabética? Possível papel da hipertensão na exacerbação da RD
• Beneficiário: Jacqueline Mendonça Lopes de Faria
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 08/54068-7 - E possível prevenir os efeitos tóxicos iniciais da hiperglicemia em retina de animais experimentalmente diabéticos através de tratamento antioxidante com tempol, um mimético da superóxido dismutase?
• Beneficiário: Jacqueline Mendonça Lopes de Faria
• Modalidade de apoio: Auxílio à Pesquisa - Regular