Effect of astragalus injection on renal tubular epithelial transdifferentiation in type 2 diabetic mice

Background: Astragalus injection is used by practitioners of traditional Chinese medicine to treat diabetic nephropathy (DN). The current study was conducted to determine the effect of astragalus on tubular epithelial transdifferentiation during the progression of DN in KKAy mice, as well as to investigate the molecular mechanism underlying this effect. Methods: Diabetic, 14- week-old, male KKAy mice were randomly divided into a model group and an astragalus treatment group, while age-matched male C57BL/6 J mice were selected as controls. The treatment group received daily intraperitoneal injections of astragalus (0.03 mL/10 g per day), while the model group received injections of an equal volume of saline. Mice were euthanized after 24 weeks. Serum samples were obtained from the animals in each group for blood glucose measurement. Kidney tissue samples were used for morphometric studies. The mRNA and protein expression levels of transforming growth factor beta 1 (TGF-beta 1), transforming growth factor beta receptor 1 (TGF beta-R1), alpha smooth muscle actin (a-SMA), and E-cadherin were evaluated using real-time polymerase chain reaction (PCR) and western blotting. Results: Astragalus significantly reduced blood glucose levels; inhibited morphological changes in the kidneys of KKAy mice; reduced mRNA and protein expression levels of TGF-beta 1, TGF beta-R1, and a-SMA; and increased E-cadherin expression. Conclusions: Tubular epithelial transdifferentiation plays an important role in the development of DN in diabetic mice. Administration of astragalus likely prevents or mitigates DN by suppressing tubular epithelial transdifferentiation, protecting KKAy mice from renal damage.