Amygdalin alleviates renal injury by suppressing inflammation, oxidative stress and fibrosis in streptozotocin-induced diabetic rats

To explore the protective efficacies and potent mechanism of amygdalin on high glucose-cultured renal cell HBZY-1 in vitro and streptozotocin (STZ)-induced diabetic nephropathy (DN) rat in vivo. The cellar proliferation and generation of ROS in high-glucose cultured HBZY-1 cell were assessed by MTT and DCFH-DA assay, respectively. The fasting blood glucose levels, renal function and inflammation indexes as well as oxidative stress markers in STZ-induced diabetic rats were all measured. The histologic renal section was stained with Mason and periodic acid-Schiff (PAS) method. Immunohistochemistry and western blotting methods were applied to assess expression levels of extracellular matrix (ECM), epithelial-mesenchymal transition (EMT)-related as well as TGF-β1/Smad signaling pathway-related proteins. Firstly, amygdalin significantly suppressed the excessive cell proliferation and ROS generation in HBZY-1 cells cultured with high glucose. The hyperglycemia, 24 h-UP excretion, BUN and Scr of DN rats were significantly attenuated after the chronic treatment of amygdalin. Moreover, MDA, SOD, IFN-γ and IL-12 levels in kidney tissues were all effectively reduced. Besides, amygdalin can suppress the ECM accumulation and EMT transformation by inhibiting Smad/TGF-β pathway to alleviate the renal fibrosis in renal tissues of DN model rats. Amygdalin ameliorates excessive oxidative stress, inflammation and renal tissue fibrosis of DN mainly by suppressing TGF-β1/Smad signaling pathway and regulating the key enzymes of ECM degradation.