Protective effect of Humic acid against Diabetic Retinopathy in streptozotocin-induced diabetic rats

Diabetes mellitus (DM) is a growing global health concern, often leading to complications such as diabetic retinopathy (DR), primarily due to chronic hyperglycemia. DR is associated with oxidative stress, microvascular damage, and inflammation. Humic acid (HA), a natural polyphenolic antioxidant, has demonstrated free radical-scavenging properties. The purpose of this study was to evaluate the protective effect of HA against DR in streptozotocin (STZ) -induced diabetic rats. DR was induced with a single intraperitoneal dose of STZ (55 mg/kg). Diabetic rats were then treated orally with HA at 100, 500, and 1000 mg/kg for 90 days. Key parameters measured included blood glucose, HbA1c, body weight, total cholesterol (TC), triglycerides (TG) and retinal morphometry. HA treatment significantly reduced blood glucose levels, improved body weight, and normalized lipid profiles. It also lowered oxidative stress in ocular tissues by decreasing lipid peroxidation and enhancing antioxidant levels. Histological analysis revealed notable recovery of retinal structure following HA treatment. These findings suggest that HA exerts a protective effect against DR by improving metabolic balance, reducing oxidative stress, and preserving retinal integrity, thereby indicating its potential as a therapeutic agent in diabetes-related ocular complications.