Quercetin Protect the Rat Retina From Light–induced Damage

Abstract

Abstract: : Purpose:We examined the protective effect of quercetin in light exposed rat retina focusing on their anti–oxidative and anti–apoptotic effects. Methods:Splague–Dawley (SD; 6–weeks old, male) rats were maintained on a cycle of 12 hours of light and 12 hours for 2weeks. Quercetin (50mg/kg body weight) or saline was administered intraperiotoneally to rats for 6 days and 2 hours before the exposure. The intense white fluorescent light (3,000 lx) was exposed to rats for 24 hours. Water and Purina rat chow were provided ad libitum. Histological damage was determined by the thickness of the outer nuclear layer (ONL) in relation to the thickness of the entire retina. Oxidative stress was determined by immunostain using antibody against 8–hydroxy–deoxyguanosine (8–OHdG) and the number of phagosomes, fragment of rod outer segments, in retinal pigment epithelium (RPE). Hsp70 and c–Fos expression was measured by Western blot analysis. Apoptotic cells were detected using TdT–mediated dUTP nick end labeling (TUNEL) method. To determine the apoptotic pathway, we employed Electrophoretic Mobility Shift Assay (EMSA). Results:Quercetin treated retina was alleviated histological damage and oxidative stress by light exposure. However, in quercetin untreated retina (saline administered retina), many 8–OHdG labeling cells were observed in ONL and RPE during and after exposure and RPE had numerous phagosomes, arrangement of ROS was disrupted. Hsp70 and c–Fos expression was enhanced by light exposure and suppressed with quercetin treatment. TUNEL positive cells were observed in ONL during and after light exposure in quercetin untreated retina. On the other hand, little number of TUNEL positive cells were observed in quercetin treated retina. EMSA revealed the involvement of AP–1 in apoptosis in light exposed retina and the inhibition of binding c–Fos and c–Jun to AP–1 by quercetin treatment. Conclusions:With quercetin treatment, the retina was protected by light induced–damage, thus quercetin is the effective agent having anti–oxidative and anti–apoptotic effects.

Keywords: retina • antioxidants • apoptosis/cell death