17 beta Estradiol protects SD rat retina from light damage via antioxidative effect

Abstract Our previous studies have proved that 17 beta Estradiol (beta E2) could protect SD rat retinal neurons against light induced apoptosis. The present study was aimed at finding out whether beta E2 could protect retinal neurons from light damage by antioxidative effects. The light damage animal model was constructed using 250±10 g male and female (ovariectomized) SD rats exposuring to 8000 lux white light for 12 hours. 4 μl beta E2 (final concentration was 100 μM) or saline was injected to rats by intravitreous injection before exposure to the light. Electroretinogram (ERG) and HE staining were used to investigate the neuroprotective effect of beta E2. Content of oxidative stress products-reactive oxygen species (ROS) and maleic dialdehyde (MDA), activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were detected by biochemical kits in order to assess the antioxidative effects of beta E2. Our results showed that exposed to 8000 lux white light for 12 h resulted in obvious functional and morphological damage in both male and female SD rat retina: the amplitude of Rod-a, b wave and Max-a, b wave decreased sharply; numbers of outer nuclear layer and cells lost significantly; the gradual fusion of outer nuclear layer and inner nuclear layer lead to structural confusion and disappearance of outer plexiform layer. While pre-intravitreous injection with 4 μl beta E2 significantly attenuated that damage on rat retina. In addition, after exposuring to light, oxidative stress products-ROS and MDA-in retina increased while the activity of antioxidant enzymes-SOD, CAT and GPx-decreased. Nevertheless, ROS and MDA were reduced and the activity of SOD, CAT and GPx was raised by administration of beta E2. These results suggested that beta E2 could effectively protect retina from light damage in SD rat and it possibly play such neuroprotective effect by antioxidation.