Abstract
Diabetic nephropathy (DN) is a major cause of chronic renal failure in diabetic patients worldwide. Betaine, a zwitterionic quaternary ammonium salt compound, is involved in numerous biological processes. The present study aimed to investigate the effects of betaine on mouse mesangial cells (MMCs) cultured under high glucose (HG) conditions and its underlying mechanisms. MMCs were treated with betaine under HG conditions. Cell proliferation and the cell cycle distribution were investigated with an MTT assay and flow cytometry, respectively. Western blotting and reverse transcription‑quantitative polymerase chain reaction analyses were applied to respectively determine protein and mRNA expression levels. The results suggested that betaine decreased cell proliferation in a dose‑dependent manner, while G1‑phase arrest was significantly induced in MMCs. Compared with the control group, the expression levels of p21 and p27 decreased under HG conditions, but were reversed by betaine. Furthermore, the expression levels of fibronectin and type IV collagen were significantly decreased in cells treated with betaine compared with the HG group. Additionally, betaine decreased the phosphorylation of Akt, extracellular‑signal‑regulated kinase (Erk)1/2 and p38 mitogen‑activated protein kinase (MAPK), but was enhanced under HG conditions. Overall, the results of the present study indicated that betaine serves a protective role in HG‑induced MMCs by inhibiting cell proliferation and extracellular matrix deposition via regulating regulation of the Akt/Erk1/2/p38 MAPK signaling pathway.