Modulatory effects of rice bran and its oil on lipid metabolism in insulin resistance rats

Abstract

The study was designed to evaluate the effects of rice bran (RB) or its oil (RBO) on lipid metabolism, hepatic insulin receptor substrate-1 (IRS-1) and hepatic expression of 3-hydroxy-3-methylglutaryl-Co A (HMG-CoA) reductase in rats fed high-fructose diet (HFD). Rats were divided into four groups: Group 1, animals received standard diet as control, while groups 2, 3 and 4 were fed on a HFD. Groups 3 and 4 animals fed HFD containing RB (5%) instead of cellulose and RBO (10%) instead of corn oil, respectively for 5 weeks. Fructose feeding to rats caused significant elevations in plasma glucose, serum insulin, and lipid profile, while serum total antioxidant capacity was significantly reduced compared to control. Hepatic concentration of IRS-1 was decreased while malondialdehyde (MDA) and HMG-CoA reductase mRNA were elevated compared to control group. Addition of RB or RBO to fructose fed rats alleviated the hazardous effects of fructose. Practical applications Rats fed high-fructose diet were used as a model of insulin resistance accompanied by deleterious metabolic consequences including hyperinsulinemia, hyperglycemia, glucose intolerance, hypertriglyceridemia and hypertension in rats and these metabolic effects are similar to those observed in human multi-metabolic syndrome X. Supplementation of rice bran or rice bran oil to fructose-fed rats improves insulin resistance and reduces lipo- and glucotoxicity.