RESUMO
Age-related macular degeneration (AMD) is among the increasing number of diseases causing irreversible blindness in the elderly. Dry AMD is characterized by the accumulation of lipofuscin in retinal pigment epithelium (RPE) cells. N-Retinylidene-N-retinylethanolamine (A2E), a component of lipofuscin, is oxidized to oxo-A2E under blue light illumination, leading to retinal cell death. The aim of this study was to investigate the protective effect and mechanism of quercetin-3-O-α-l-arabinopyranoside (QA) against blue light (BL)-induced damage in both RPE cells and mice models. Treatment by QA inhibited A2E uptake in RPE cells, as determined by a decrease in fluorescence intensity. QA also protected A2E-laden RPE cells against BL-induced apoptosis. QA inhibited C3 complement activation and poly (ADP-ribose) polymerase (PARP) cleavage, as determined by western blotting. QA showed an inhibitory effect on AP1 and NF-kB activity as estimated in a reporter gene assay. In addition, QA activated the gene expression of aryl hydrocarbon receptor target genes (CYP1A1, CYP1B1) in TCDD-treated RPE cells. In the mice model, oral administration of QA protected against retinal degeneration induced by BL exposure as determined by histological analyses (thickness of retinal layers and immunostaining for caspase-3). In addition, QA inhibited apoptosis and inflammation via inhibition of NF-kB p65 translocation, C3 activation, and PARP cleavage. Collectively, these results revealed the protective mechanism of QA against BL-induced retinal damage both in vitro and in vivo.
Assuntos
Apoptose/efeitos da radiação , Suplementos Nutricionais , Luz/efeitos adversos , Degeneração Macular/prevenção & controle , Quercetina/análogos & derivados , Protetores contra Radiação/uso terapêutico , Epitélio Pigmentado da Retina/metabolismo , Absorção Fisiológica/efeitos da radiação , Animais , Anti-Inflamatórios não Esteroides/administração & dosagem , Anti-Inflamatórios não Esteroides/metabolismo , Anti-Inflamatórios não Esteroides/uso terapêutico , Linhagem Celular , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos da radiação , Regulação da Expressão Gênica/efeitos da radiação , Genes Reporter/efeitos da radiação , Humanos , Degeneração Macular/etiologia , Degeneração Macular/metabolismo , Degeneração Macular/patologia , Masculino , Camundongos Endogâmicos BALB C , Microscopia de Fluorescência , Oxirredução , Quercetina/administração & dosagem , Quercetina/metabolismo , Quercetina/uso terapêutico , Protetores contra Radiação/administração & dosagem , Protetores contra Radiação/metabolismo , Distribuição Aleatória , Epitélio Pigmentado da Retina/imunologia , Epitélio Pigmentado da Retina/patologia , Epitélio Pigmentado da Retina/efeitos da radiação , Retinoides/metabolismo , Retinoides/efeitos da radiaçãoRESUMO
A bacterial plasmid was constructed on which the regulatory region of the umuC gene of Escherichia coli was fused to the coding sequence of the green fluorescent protein gene (gfp) from the jellyfish Aequorea victoria. Escherichia coli AB1157 strains carrying the plasmid emitted fluorescence in the presence of mutagens that induce the SOS DNA repair system. Data on tests with nitrosoguanidine, methylmethane sulphonate and UV radiation (254 nm) are presented. Although fluorescent detection using this system was not as rapid or sensitive as a similar luminescent equivalent (umuC-luxAB), the gfp reporter system was more robust. Escherichia coli umu gene induction was also analysed in Salmonella typhimurium TA1537 cells following plasmid transfer and exposure to the same range of mutagens. There was no significant difference in sensitivity between the two species. These preliminary results will provide the basis for development of mutagenicity test systems useful in the testing of complex mixtures, such as environmental samples, and the investigation of physiological parameters influencing spontaneous mutagenesis in bacteria.