Effect of rice-bran water extract on energy metabolism in rats fed a high-fat diet

Abstract

Insulin resistance and some chronic un-communicable diseases have long been known to associate with obesity. The altered energy metabolism is verified, in part, by observing fat accumulation in fat tissues and liver as well as analyzing the acetyl CoA carboxylase (ACC) in liver, lipid profile in blood and oral glucose tolerance. The study was carried out in 7 groups of Sprague Dawley rats. Rats in group 2-7 were fed with high-fat diet (HF) while group 1 is the control group where rats were fed with standard chow. RBE at doses of 220.5, 2205 and 4410 mg/kg rat weight and metformin at the doses of 19.10 and 38.20 mg/kg rat weight were also fed in group 3-7, respectively. Oral glucose tolerance was tested at the end of forth week. Then, all rats were killed and specimens were collected. The results showed that the mean ± SEM of abdominal fat weight (7.65 ± 0.29 vs. 4.73 ± 0.39), fat cell size (4919.76 ± 453.59 vs. 2835.23 ± 249.15) and triglyceride level in liver (2.50 ± 0.26 vs. 1.48 ± 0.08) were increased whereas HDL-c (67.14 ± 1.62 vs. 77.20 ± 2.82) was decreased in rats fed with HF alone as compared to rats fed with chow. At least 2205 mg RBE/kg rat weight or 19.10 mg metformin/kg rat weight were significantly reduced abdominal fat weight (6.57 ± 0.25, 6.26 ± 0.39), fat cell size (3545.97 ± 146.60, 3523.60 ± 9.16) and triglyceride levels in liver (1.98 ± 0.11, 1.69 ± 0.10) in comparison to rats fed with HF alone. ACC activity was also increased in HF group when compared with the control group and the activities retuned to normal when HF groups were also received RBE or metformin, though there were no statistic significance. In conclusion, HF was able to give fat accumulation. One aspect of the mechanism could be the increased fat synthesis in liver as well as poor fat disposition as evidenced by increased triglyceride content in liver but low HDL-c. Both RBE and metformin were able to ameliorate the alteration.

Key words: Rice bran extract, Fat deposit, Fatty acid synthesis