Protective effects of astragalosides IV on renal proximal tubular epithelial cell injury induced by high glucose

Abstract

Objective To investigate the protective effects of astragalosides Ⅳ (ASI) on high glucose-induced renal proximal tubular epithelial cells (NRK-52E). Methods NRK-52E were cultured and divided randomly into three groups: control group, high glucose group (HG in short), ASI groups (with various doses). Cells were treated with increasing concentrations of ASI (20, 40, 80 and 100 μg/ml) for 24 h in high glucose and we also stimulated cells in ASI 100 μg/ml with high glucose for various lengths of time. The apoptosis rate was detected by flow cytometric analysis. The mRNA and protein expression of transforming growth factor-β1 (TGF-β1), α-smooth muscle actin (α-SMA), Smad2, Smad3 and their phosphorylated forms were detected by real-time polymerase chain reaction (PCR) and Western blot, respectively. Results Compared with the control group, apoptosis was increased in the high glucose group (P<0.01). However, ASI inhibited high glucose-induced cell apoptosis in a dose-dependent manner, with a maximal inhibitory effect achieved at 100 μg/ml (P<0.05). The significant inhibition caused by ASI was observed at 8h after the start of pretreatment (P<0.05) and increased in a time-dependent manner. ASI can inhibit the expression of TGF-β1, α-SMA, Smad2, Smad3 both at mRNA and protein level. Conclusions ASI inhibited NRK-52E cells apoptosis induced by high glucose and reduced expression of TGF-β1, α-SMA, Smad2, Smad3 both at the mRNA and protein level in NRK-52E cells, thus delayed epithelial-to-mesenchymal transition progress. Key words: Astragalus membranaceus; Saponins/PD; Kidney tubules; Epithelial cells/DE; Diabetic nephropathies; Rats