Dietary Taurine Reduces Retinal Damage Produced by Photochemical Stress Via Antioxidant and Anti-apoptotic Mechanisms in Sprague-Dawley Rats

Taurine has been shown to be tissue protective in many models of oxidant-induced injury. However, its protective role against retinal damage induced by photochemical stress is less well known. The purpose of the present study was to investigate whether dietary taurine reduced retinal photochemical damage in Sprague-Dawley rats and to further explore the underlying molecular mechanisms of this action. Twenty rats fed AIN-93 formulation and maintained in the dark for 48 h were used as controls (n 20). Another forty rats were randomly divided into two groups and then treated with (n 20) or without 4 % taurine (n 20) for 15 d respectively. After treatment, these two groups were exposed to fluorescent light (3000 +/- 200 lux and 25 degrees C), and the protective effects of dietary taurine were then evaluated. The present results showed that dietary taurine effectively prevented retinal photochemical damage as assessed by changes of morphology. Also, the supplementation caused an increase of taurine in the retina, a decrease of malondialdehyde (P < 0.01), and elevation of superoxide dismutase (P < 0.01) and glutathione peroxidase activities in the retina (P < 0.01). Moreover, dietary taurine inhibited activator protein-1 (AP-1) (c-fos/c-jun subunits) expression (P < 0.05), up regulated NF-kappaB (p65) expression (P < 0.05), and decreased caspase-1 expression (P < 0.05) so as to reduce the apoptosis of photoreceptors in the retina (P < 0.05). These results suggest that dietary taurine reduced retinal damage produced by photochemical stress via antioxidant and anti-AP-1-NF-kappaB-caspase-1 apoptotic mechanisms in rats.