Lutein protects RGC-5 cells against hypoxia and oxidative stress

Abstract

Retinal ischemia and oxidative stress lead to neuronal death in many ocular pathologies. Recently, we found that lutein, an oxy-carotenoid, protected the inner retina from ischemia/reperfusion injury. However, it is uncertain whether lutein directly protects retinal ganglion cells (RGCs). Here, an in vitro model of hypoxia and oxidative stress was used to further investigate the neuroprotective role of lutein in RGCs. Cobalt chloride (CoCl(2)) and hydrogen peroxide (H(2)O(2)) were added to a transformed RGC cell line, RGC-5, to induce chemical hypoxia and oxidative stress, respectively. Either lutein or vehicle was added to cultured cells. A higher cell count was observed in the lutein-treated cells compared with the vehicle-treated cells. Our data from this in vitro model revealed that lutein might protect RGC-5 cells from damage when exposed to either CoCl(2)-induced chemical hypoxia or H(2)O(2)-induced oxidative stress. These results suggest that lutein may play a role as a neuroprotectant.

Keywords: RGC-5; antioxidants; carotenoids; cobalt chloride; hydrogen peroxide; ischemia.

Figure 1.

Light micrographs and cell count of RGC-5 cells treated with cobalt (II) chloride (CoCl₂; 300 μM). (a) Normal control. (b) Vehicle treatment. (c) Lutein treatment at 10 μM. (d) Lutein treatment at 20 μM. CoCl₂-induced hypoxia led to cell death in the vehicle-treated group (b) compared with control (a). However, 20 μM lutein treatment reversed the cytotoxic effect of CoCl₂ (d). (e) Count of RGC-5 cells treated with CoCl₂ referenced to the normal control. A decreased cell number was observed for the vehicle-treated group (*p < 0.05 versus control). However, an increased RGC-5 cell number was observed after 20μM lutein treatment (^#p < 0.05 versus vehicle-treated). Scale bar, 25 μm. Error bars, SEM.

Figure 2.

Light micrographs and cell count of RGC-5 cells treated with hydrogen peroxide (H₂O₂; 300 μM). (a) Normal control. (b) Vehicle treatment. (c) Lutein treatment at 10 μM. (d) Lutein treatment at 20 μM. H₂O₂-induced oxidative stress led to cell death in the vehicle-treated group (b). Lutein treatment reversed the cytotoxic effect (c and d). (e) Cell count in RGC-5 cells treated with H₂O₂. Cell count referenced to the normal control. H₂O₂ exposure led to a decrease in cell number in the vehicle-treated group (**p < 0.01 versus control). However, both 10 μM and 20 μM lutein treatment protected RGC-5 cells from damage (^#p < 0.05 versus vehicle-treated control). Scale bar, 25 μM. Error bars, SEM.