Obesity is one of major health challenges in the industrial world. Although rice hull has been reported to show various bioactivities, no studies have evaluated its anti-obesity effect. We hope to demonstrate the anti-obesity effect of rice hull extract (RHE) and the underlying mechanism in high-fat diet (HFD)-induced obese mice and 3T3-L1 preadipocytes. Serum lipid profiles were determined by enzymatic methods. Histological analysis of liver and epididymis fat tissues was carried out with hematoxylin and eosin stain. The mRNA expression of adipogenic markers was analyzed with qRT-PCR and western blotting. Oral administration of RHE reduced body weight gain and fat accumulation in HFD-fed mice. RHE also reduced lipid accumulation by inhibiting the mRNA expression of adipogenic-related genes in HFD-fed obese mice and differentiated preadipocytes. The downregulation of adipogenesis by RHE was mediated through the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC). In addition, RHE induced the phosphorylation of c-Jun N-terminal kinases (JNK) and extracellular-signal-regulated kinases (ERK) in liver and epididymis adipose tissues of HFD-fed obese mice. Taken together, these findings indicate that RHE could inhibit the differentiation of adipose cell and prevent HFD-induced obesity, suggesting its potential in the prevention of obesity and metabolic syndrome and related-disorders.
Keywords: AMP-activated protein kinase; MAPK; high-fat diet; obesity; rice hull extract.