Abstract: This study aimed to observe the antiobesity and lipid-lowering effects of wheat bran polyphenols (WBP) in diet-induced obese rats, and to explore its possible mechanism. Eighty 6-week-old SD rats, half from each gender, were adaptively fed for one week. Ten rats were randomly selected from them and fed on a basal diet to serve as a blank control group. The remaining 70 rats were fed on a high-fat diet until the body mass gain exceeded 20%. Totally 50 obese rats were selected from the 70 rats and randomly divided into five groups of 10 rats each: model (distilled water 5.0 mL/kg mb), positive control (trimethylglycine (TMG), 0.10 g/kg mb), low-dose WBP (WBP-L, 1.50 g/kg mb), medium-dose WBP (WBP-M, 3.00 g/kg mb), and high-dose WBP (WBP-H, 6.00 g/kg mb). Each drug was administered daily at a dose of 5.0 mL/kg mb by gavage. The rats in the blank control group were gavaged with distilled water (5.0 mL/kg mb) for nine weeks. During the intervention period, body mass and food intake of the rats were measured once a week and food effect was calculated. After completion of the intervention period, the rats were fasted for 12 hours with access to water and then anesthetized with ether to collect blood samples from the abdominal aorta and liver and surrounding adipose tissue to calculate liver coefficients and obesity indexes. Sera were separated from the blood samples for measurement of biochemical indicators. Liver tissues were homogenized for analyses of antiinflammatory and antioxidant parameters. Moreover, the degree of hepatic steatosis was pathohistologically observed. The results showed that WBP at all doses could reduce the food effect, inhibit the body mass gain in obese rats, reduce the liver mass and liver coefficient, and significantly lower the levels of triglycerides (TG), total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and creatinine (CREA) in the sera of obese rats. In addition, all doses of WBP decreased the levels of interleukin-6 (IL-6), IL-1β. tumor necrosis factor-α (TNF-α), adiponectin (ADPN) and leptin (LEP) in the liver homogenate of obese rats to varying degrees, but significantly increased glutathione peroxidase (GSH-Px), lipoprotein lipase (LPL), and hepaticlipase (HL) levels (P < 0.05 or P < 0.01); the effect of WBP was more pronounced than that of TMG. In conclusion, WBP can exert antiobesity, lipid-lowering and hepatoprotective functions by inhibiting the degree of obesity in simple obesity rats, reducing serum lipid levels, alleviating chronic inflammation caused by obesity, and inhibiting liver injury. Therefore, WBP has the potential to be developed as a functional food and health product with antiobesity and lipid-lowering effects. This study provides a theoretical reference for scientific and reasonable development of wheat bran.

Key words: wheat bran; polyphenols; obese rats; antiobesity and lipid-lowering effects