Scopoletin protects retinal ganglion cells 5 from high glucose-induced injury in a cellular model of diabetic retinopathy via ROS-dependent p38 and JNK signaling cascade

The protective activity of scopoletin (SPT) against glucose-induced cataract has been attributed to attenuation of aldose reductase activity and oxidative stress in a rat model. The present investigation was aimed to study the protective effect and mechanism of SPT in retinal ganglia cells (RGC) under oxidative stress and apoptosis induced by hyperglycemia. The RGC-5 cells were pre-conditioned with variable SPT concentrations for 6 hours and then subjected to hyperglycemia for 48 hours. The cell viability, mito- chondrial membrane potential (MMP) and oxidative stress markers were quantified. Western blotting was employed to screen the expression of mitogen-activated protein kinase (MAPK) and various apoptosis related proteins. SPT blocked the high-glucose induced cell injury and normalized the mitochondrial functioning via lowering the loss of MMP and release of cytochrome c. Pretreatment with SPT suppressed the enhanced ROS, malondialdehyde, and protein carbonyl content triggered by high-glucose exposure in RGC-5 cells. SPT normalized the apoptotic proteins in RGC-5 cells. The phosphorylation of c-Jun N-terminal kinases (JNK) and p38 MAPK in RGC-5 due to hyperglycemia was attenuated by SPT. Overall, SPT exhibited a protective effect in RGC-5 cells exposed to a high-glucose environment via its antioxidant efficacy, inhibition of apoptosis and modulation of the ROS-dependent p38/JNK signaling cascade.