| Summary: | 碩士 === 臺北醫學大學 === 保健營養學研究所 === 95 === The aim of this study is to investigate the effect of rice bran on lipid metabolism and hepatic mRNA expression in hamsters. Rice bran is a byproduct of the rice milling process. It contains a high level of dietary fiber (25%). Many animal studies indicate that rice bran may contribute to the lowering of plasma levels of various components of the lipid profile. However, how rice bran affects hepatic mRNA related to plasma and hepatic lipid regulation and cholesterol homeostasis is unknown. Forty 8-week-old male hamsters were first fed a high fat diet (modified AIN-93M diet containing 4% soybean oil plus 4% lard) and supplemented with 0.2% cholesterol for 2 weeks and then divided into five groups. The control group was fed modified AIN-93M diet without cholesterol (NC), and the experimental groups were fed modified AIN-93M diet plus 0.2% cholesterol and either 0% (CC), 5% (R5), 10% (R10), or 15% (R15) rice bran for 4 weeks. The results showed that plasma and hepatic triglyceride and cholesterol concentrations were lower in hamsters fed the rice bran diet than hamsters fed the CC diet. Besides, the plasma LDL-C concentrations and LDL-C/HDL-C ratio were lower and the plasma short chain fatty acid concentrations, fecal neutral sterol, and bile acid excretion were higher in the rice bran group than the CC group. After 4 weeks, the rice bran diet resulted in lower hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) mRNA expression. Hepatic HMG-CoA reductase mRNA expression was significantly lower and hepatic LDL receptor mRNA expression was significantly higher in the R15 group than R5 group. Moreover, hepatic cholesterol 7α-hydroxylase (CYP7A1) mRNA expression was higher in the groups fed rice bran than those fed the CC diet. Additionally, the R5 group had higher hepatic lipoprotein lipase, scavenger receptor class B type 1 (SR-B1), and acyl-CoA oxidase (ACO) mRNA expression than the CC group. These findings suggest that the rice bran diet regulates the lipid and cholesterol mechanism in hamsters.
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