Hordenine protects against hyperglycemia-associated renal complications in streptozotocin-induced diabetic mice

•Combination of HOR and insulin reduce blood glucose level in diabetic mice.•HOR and insulin function synergistically to ameliorate renal injury in diabetic mice.•HOR and insulin play synergistic roles to inhibit inflammation and fibrosis in kidney.•HOR and insulin function synergistically to enhance antioxidant defense in kidney.•HOR functions synergistically with insulin and prevents diabetic nephropathy. The worldwide prevalence of diabetes and associated metabolic diseases has dramatically increased. Pharmacological treatment of diabetes is still limited. Hordenine (HOR), a phenethylamine alkaloid, is a natural constituent in many plants. The present study was designed to explore the possible anti-diabetic effect of HOR in streptozotocin (STZ)-induced diabetic mice. Combined treatment of HOR and insulin significantly reduced fasting and postprandial blood glucose level in diabetic mice. HOR and insulin did not show evident protective effect against structural and functional injuries of pancreas. Renal histological and functional injuries were significantly improved by HOR or insulin treatment. Moreover, combined treatment of HOR and insulin resulted in a more significant amelioration of renal histological and functional injuries in diabetic mice. HOR induced a decrease of renal IL-1α/β and IL-6 expression, and a reduction of Col1α1 and MMP9 expression and PAS-stained mesangial expansion in glomeruli of diabetic mice. In diabetic mice, HOR significantly decreased Nrf2 expression and increased hnRNPF and hnRNPK expression in kidney. Moreover, HOR showed a synergistic effect with insulin on the expression of these regulators. Renal ROS level and TBARS content in diabetic mice were decreased by HOR. The reduction of renal expression of antioxidant enzymes in diabetic mice was inhibited by HOR and insulin. Furthermore, HOR and insulin function synergistically to play an antioxidant role against oxidative injury in diabetic nephropathy. In conclusion, to the best of our knowledge, we, for the first time, found the anti-diabetic, anti-inflammatory, and anti-fibrotic role of HOR in combination with insulin. HOR functions synergistically with insulin and prevents diabetic nephropathy. However, the molecular mechanism of the synergistic effect of HOR and insulin needs to be elucidated.