Protocatechuic acid attenuates ferroptotic and apoptotic signaling in the kidney of streptozotocin-induced diabetic rats

Abstract

Diabetic nephropathy (DN) is a major complication of diabetes, largely driven by chronic hyperglycaemia and oxidative stress. This study investigated the dose-dependent effects of protocatechuic acid (PCA) on DN, focusing on its potential to attenuate ferroptosis and apoptosis in a streptozotocin-induced type 1 diabetes rat model. Thirty-two Wistar-Albino rats were divided into four groups (n = 8): Control, Diabetes, Diabetes + PCA 50 mg/kg, and Diabetes + PCA 100 mg/kg. After 12 weeks, kidney tissues were evaluated histologically (Perls’ Prussian blue, Periodic Acid–Schiff (PAS)), immunohistochemically (Bax, Bcl-2, Caspase-3, Caspase-9, Acyl-CoA Synthetase Long Chain Family Member 4 (ACSL4), glutathione peroxidase 4 (GPx4), transferrin receptor-1 (TfR-1), and by TUNEL assay. Diabetic rats exhibited iron accumulation, tubular dilatation, intracellular vacuolization, sclerotic glomeruli, and mesangial expansion (p < 0.05), while tubular atrophy, hyaline deposition, and mononuclear infiltration were unchanged (p > 0.05). Apoptotic and ferroptotic markers (Bax, Caspase-3, Caspase-9, ACSL4, TfR-1) increased, and Bcl-2 and GPx4 decreased (p < 0.001). PCA treatment, particularly at the 100 mg/kg dose, significantly attenuated the expression of apoptotic and ferroptotic markers and reduced the number of TUNEL-positive cells (p < 0.001). These findings suggest that PCA modulates cell death by upregulating Bcl-2 and GPx4 while downregulating Bax, Caspase-3, Caspase-9, ACSL4, and TfR-1 in renal tissues. While PCA effectively suppressed these molecular markers of injury, it did not lead to significant improvements in systemic renal function parameters such as serum creatinine and blood urea nitrogen. Thus, PCA may serve as a potential agent for mitigating cellular damage in diabetic kidney injury by targeting specific cell death pathways.