Effect of loganin on experimental diabetic nephropathy

Connective tissue growth factor (CTGF) plays a pathogenic role in diabetic nephropathy (DN). Loganin, an iridoid glucoside compound was isolated from Cornus officinalis Sieb. et Zucc. This study was conducted to investigate the efficacy of loganin on DN and to elucidate the potential mechanism. High glucose (HG) stimulated cultured human renal proximal tubular epithelial cells (HK-2) analyzed CTGF expression by Western blotting and investigated whether extracellular signal-regulated kinase (ERK) signaling pathway was involved. Streptozotocin (STZ)-induced experimental DN, randomized to receive intragastric (i.g.) of loganin. Renal tissue, blood and urine samples were collected to determine and analyze. In vitro study, loganin reduced CTGF excretion in HG-induced HK-2 cells through the ERK signaling pathway. In vivo study, I.g. of loganin 5 mg/kg or 10 mg/kg significantly ameliorated renal function and increased body weight. Meanwhile, loganin reduced renal CTGF expression by immunohistochemical staining, reduced serum levels of CTGF. Besides, there were no significant differences in blood sugar levels between the loganin groups compared to the STZ-treated group. Furthermore, loganin ameliorated renal pathology. These results suggested that loganin exerts an early renal protective role to DN. Inhibition of CTGF may be a potential target in DN therapy, which highlights the possibility of using loganin to treat DN.