Astaxanthin Protects Against Retinal Damage: Evidence from In Vivo and In Vitro Retinal Ischemia and Reperfusion Models

Purpose: Astaxanthin exhibits various pharmacological activities, including anti-oxidative, anti-tumor, and anti-inflammatory effects, and is thought to exert a neuroprotective effect via these mechanisms. The purpose of this study was to investigate the protective effects of astaxanthin on neuronal cell death using a retinal ischemia/reperfusion model.Methods: In vivo, retinal ischemia was induced by 5 h unilateral ligation of the pterygopalatine artery (PPA) and the external carotid artery (ECA) in ddY mice. Astaxanthin (100 mg/kg) was administered orally 1 h before induction of ischemia, immediately after reperfusion, at 6 or 12 h after reperfusion, and twice daily for the following 4 days. Histological analysis and an electroretinogram (ERG) were performed 5 days after ischemia/reperfusion. In vitro, cell death was induced in the RGC-5 (retinal precursor cells) by oxygen-glucose deprivation (OGD), and the rates of cell death and production of intracellular reactive oxygen species (ROS) were measured using nuclear staining and a ROS reactive reagent, CM-H(2)DCFDA.Results: Histological studies revealed that astaxanthin significantly reduced retinal ischemic damage and ERG reduction. In in vitro studies, astaxanthin inhibited cell death and ROS production in a concentration-dependent manner.Conclusions: Collectively, these results indicate that astaxanthin inhibits ischemia-induced retinal cell death via its antioxidant effect. Hence, astaxanthin might be effective in treating retinal ischemic pathologies.