Abstract
Purpose: :
A carotenoid, lutein, has biological effects as an antioxidant as well as a blue light filter. In the retina of disease models, such as an endotoxin-induced uveitis model and a diabetes model, the levels of reactive oxygen species (ROS) are reduced by lutein administration, as we have recently reported. However, it remains to be elucidated whether lutein acts directly on ROS as a scavenger or indirectly through activating phase II antioxidant enzymes and its related genes which can promote ROS catalysis. In this study, we analyze whether lutein affects expression of phase II antioxidants in a neuronal cell line, the PC12D cells.
Methods: :
The PC12D cells were cultured in Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 10% fetal bovine serum (FBS) and 10% horse serum. Cells were incubated with 50 ng/ml of nerve growth factor (NGF) together with 0.5% FBS for differentiation to neurons for 2 days. After removal of NGF, cells were applied with lutein-rich marigold extract or vehicle for 6, 9, 12 and 24 hours, and total RNA or whole cell lysate were prepared. Gene expression of phase II antioxidants was analyzed using real-time PCR. Moreover, protein expression of these molecules was measured using immunoblotting.
Results: :
Treatment with lutein-rich marigold extract induced gene expression of catalase and Pi isoform of Glutathione S-transferase, GSTP1, in the neuronal cell line. The latter was gradually upregulated in a time-dependent manner. However, there was no effect on expression of other antioxidants such as superoxide dismutase 1, superoxide dismutase 2 or 4-Nitroquinoline 1-oxide. Protein expression of GSTP1 was also elevated.
Conclusions: :
Lutein-rich marigold extract induced the expression of phase II antioxidants, catalase and GSTP1, suggesting that a pathway through which lutein indirectly reduces ROS can be involved in the lutein’s effect in reducing ROS.
Keywords: antioxidants • neuroprotection