The effect of curcumin on on intravitreal proinflammatory cytokines, oxidative stress markers, and vascular endothelial growth factor in an experimental model of diabetic retinopathy.

The prevalence of diabetic retinopathy (DR) is high among individuals with diabetes. Curcumin (CUR) has been suggested as a possible treatment for this condition. This study aimed to investigate the impact of CUR on pro-inflammatory cytokines, oxidative stress markers, and vascular endothelial growth factor (VEGF) in an experimental model of DR. The study used Spontaneously Diabetic Torii (SDT) rats and divided them into groups to receive various CUR doses (10, 50, 100 mg/kg/day) or distilled water for four weeks. Non-diabetic Sprague-Dawley (SD) rats were used as a control group. Pro-inflammatory cytokines (interleukin (IL)-1, IL-6, tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ)) (by ELISA), oxidative stress markers (superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GPX), catalase (CAT)), and VEGF expression (by RT-PCR) and content (by Western-blot and immunostaining) were assessed as outcome measures. The study found that diabetic rats who received varying doses of CUR showed a decrease in pro-inflammatory cytokines (TNF-α, IFN-γ, IL-1), oxidative stress markers (SOD, MDA, GPX, CAT), and VEGF expression and content in the vitreous. The decrease in these markers was dose-dependent and significantly different from diabetic rats who did not receive CUR (p<0.01). However, there was no significant difference in the vitreous level of IL-6 between the groups (p=0.35). The study concluded that CUR has the potential to alleviate inflammation and oxidative stress induced by diabetes in the vitreous microenvironment of rats. CUR also reduced the increase in VEGF levels in the vitreous of diabetic rats. These findings suggest that CUR could be a viable therapeutic option for the treatment of DR.