Abstract
Whole-wheat intake is known to reduce the risk of metabolic syndrome. However, the active component remains unclear. Recently, we identified bioactive peptides [leucine-arginine-proline (LRP) and leucine-glutamine‑proline (LQP)] from wheat bran autolytic hydrolysate. The present study aimed to investigate the effects of LRP and LQP on non-alcoholic steatohepatitis (NASH) in a mouse model. We also evaluated the effects of these peptides on oxidative stress and on the AMP-activated protein kinase (AMPK) signaling pathway, two major pathogenic factors of NASH. Seven‑week-old male C57BL/6 mice were fed a high-fat diet for 10 weeks and administered water supplemented with 0.05% LRP, 0.20% LRP, 0.05% LQP, or 0.20% LQP (each n=5) or distilled water (control; n=5) ad libitum. Oxidative stress was evaluated by measuring the serum levels of diacron reactive oxygen metabolite (d-ROM) and biological antioxidant potential (BAP). Hepatic expression of phosphorylated AMPK and phosphorylated acetyl-CoA carboxylase (ACC) were evaluated by immunoblotting. The result showed that non‑alcoholic fatty liver disease activity score was significantly decreased in all types of treatment. Serum d-ROM levels were significantly decreased in the 0.20% LRP group, but not in the 0.05% LRP, 0.05% LQP, and 0.20% LQP groups. Serum BAP levels were significantly increased in the 0.05% LRP and 0.20% LRP groups, but not in the 0.05% LQP and 0.20% LQP groups. Immunoblotting analysis revealed that the expression of phospho-AMPK was increased whereas that of phospho-ACC was decreased in the 0.20% LQP group. In conclusion, we demonstrated that both LRP and LQP alleviated the severity of NASH in a high-fat diet-induced NASH mouse model. In addition, we showed that LRP and LQP modulated oxidative stress and upregulated AMPK/ACC, respectively. Thus, LRP and LQP may constitute clinically applicable therapeutic agents for NASH.