Nerve growth factor protects against palmitic acid- induced injury in retinal ganglion cells

Accumulating evidence supports an important role for nerve growth factor （NGF） in diabetic retinopathy. We hypothesized that NGF has a protective effect on rat retinal ganglion RGC-5 cells injured by palmitic acid （PA）, a metabolic factor implicated in the development of dia- betes and its complications. Our results show that PA exposure caused apoptosis of RGC-5 cells, while NGF protected against PA insult in a concentration-dependent manner. Additionally, NGF significantly attenuated the levels of reactive oxygen species （ROS） and malondialde- hyde （MDA） in RGC-5 cells. Pathway inhibitor tests showed that the protective effect of NGF was completely reversed by LY294002 （PI3K inhibitor）, Akt VIII inhibitor, and PD98059 （ERK1/2 inhibitor）. Western blot analysis revealed that NGF induced the phosphorylation of Akt/FoxO1 and ERK1/2 and reversed the PA-evoked reduction in the levels of these proteins. These results indicate that NGF protects RGC-5 cells against PA-induced injury through anti-oxidation and inhibition of apoptosis by modulation of the PI3K/Akt and ERK1/2 signaling pathways.