Phenolic Compounds from Rice Bran Ameliorate Hyperglycemia in High Fat Diet-induced Mice

Abstract

Abstract Objectives To clarify that phenolic compounds in rice bran play a role in regulating lipid metabolism, we used high-fat diet-induced mice to investigate effects of rice bran phenolic extract on lipid metabolism, and related mechanism are also explored. Methods Male C57BL/6J mice were randomly divided into 4 groups of 20 animals each. The mice in the normal control group (NC) were fed with the purified D12450H diet (10% energy from fat), while the other 3 groups were fed with the purified high fat (HF) diet D12451 (45% energy from fat) ad libitum to induce dyslipidemia. In the HF + LP and HF-HP groups, RBPE was administered intragastrically every day at the dose of 200 mg/kg/d and 400 mg/kg/d, respectively together with the intake of HF diet. After 16 weeks’ treatment, the animals were fasted for 12 h and then anesthetized withr ether. Results High-Fat Diet administration for 16 weeks significantly increased the weights of liver and adipose tissue mass and induced increased levels of total cholesterol, triglyceride, and low-density lipoproteins cholesterol and decreased high-density lipoproteins cholesterol. Long-term intake of RBPE (200 mg/kg/d and 400 mg/kg/d) could significantly improve lipid profiles in serum. Histological analysis and oil red O staining results showed that RBPE could ameliorate liver steatosis and inhibit adipocytes enlargement and lipid filling in epididymal fat tissue. Besides, RBPE could alleviate oxidative stress in liver, which might be responsible for its protective effect on liver steatosis. Further study showed that RBPE might regulate lipid metabolism through promoting the activation of 5' adenosine monophosphate (AMP)-activated protein kinase (AMPK)α, thereby inhibiting expressions of sterol regulatory element-binding protein 1c (SREBP-1c) and 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGR). Conclusions RBPE might regulate lipid metabolism through AMPKα-mediated SREBP-1c and HMGR pathways. These results provide us new evidences of the health effect of rice bran and encourage us consume more brown rice instead of refined rice. Funding Sources This study was supported by National Natural Science Foundation of China, Group Program of Natural Science Foundation of Guangdong Province and the Guangdong Provincial Special Fund for Modern Agriculture Industry Technology Innovation Teams.