Effects of Curcumin on Inflammation in a Rat Model of Diabetic Retinopathy

Background: Diabetic retinopathy (DR) is a leading cause of vision loss, with oxidative stress and inflammation serving as critical drivers of its onset and progression. Curcumin, a natural polyphenol, is known for its potent anti-inflammatory and antioxidant properties. Glial fibrillary acidic protein (GFAP) is commonly used as an indicator of retinal macroglial reactivity, whereas the NLRP3 inflammasome is an important mediator of inflammatory signaling in DR. We evaluated retinal vascular abnormalities and retinal GFAP immunoreactivity and examined whether these findings were accompanied by changes in retinal NLRP3 and IL-1β protein abundance and in the levels of cleaved caspase-1 and cleaved GSDMD. Methods: Diabetes was induced in 7-week-old rats via a single intraperitoneal injection of streptozotocin. Following the confirmation of hyperglycemia, curcumin was administered orally. To evaluate the effects, we performed trypsin digestion, haematoxylin and eosin (H&E) staining, fluorescein isothiocyanate (FITC)-dextran permeability assays, immunofluorescence staining, and Western blotting on the harvested retinas. Results: The DM group showed increased acellular capillary formation, vascular leakage, retinal GFAP immunoreactivity, NLRP3 and IL-1β protein abundance, and levels of cleaved caspase-1 and cleaved GSDMD. Compared with the untreated DM group, the DM + curcumin group showed lower values for all of these outcomes. Conclusions: In diabetic rats, oral administration of a curcumin-containing formulation was associated with fewer retinal vascular abnormalities and lower GFAP immunoreactivity, accompanied by parallel differences in inflammasome-related proteins. These findings support the potential of this formulation as an adjunctive therapeutic approach for early diabetic retinopathy.