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.

Amelioration of Insulin Resistance in Rats Treated with Rice Bran Oil

“…The present study demonstrated that, RBO reduced the level of insulin and HOMA-IR, compared to normal control and fructose fed rats (HFD1and HFD2). These results are in line with Abd El-Wahab et al (18) , who reported that supplementation of rice bran oil to fructose-fed rats improves insulin resistance and reduces lipo-and glucotoxicity. The present work illustrated that, feeding rats with HFD for 4 weeks did not alter serum cholesterol (sCHO) and TG levels, while feeding rats for 8 weeks elevated its level, compared to NC and those fed HFD for one month.…”

Rice Bran Oil Improves Insulin Resistance by Affecting the Expression of Antioxidants and Lipid‐Regulatory Genes

“…In the present study, insulin-resistant rats (HFD1 and HFD2) displayed impairment in the antioxidant defense system indicated by a highly significant reduction in hepatic SOD and CAT activities accompanied by significant elevation in hepatic MDA, compared to the control group. The current results agree with those of many previous studies (Abd El-Wahab et al, 2017;Abdel-Kawi et al, 2016;Mahfouz et al, 2010;Rajasekar, Viswanathan, & Anuradha, 2008).…”

“…The present study demonstrated that administration of RBO reduced the level of insulin and HOMA‐IR, compared to NC and fructose‐fed rats (HFD1and HFD2). These results agree with those of Abd El‐Wahab et al (), who reported that HFD containing RBO improves insulin sensitivity and reduces lipo‐ and glucotoxicity. Shakib, Gabrial, and Gabrial () showed that the glucose lowering effect of RBO may be due to its content of oleic acid.…”

“…The improvement in antioxidant capacity, which was characterized by increasing the activity of SOD and CAT, in addition to the reduction of the hepatic MDA content, was noticeable and pronounced in rats fed RBO‐containing diets (HFD1 + RBO and HFD2 + RBO) as compared to their respective control. These results are in harmony with those reported by Al‐Okbi et al (), Araghi et al (), and Abd El‐Wahab et al (). The most important antioxidants in RBO are γ‐oryzanol and tocotrienols (Chotimarkorn, Benjakul, & Silalai, ; Posuwan et al, ).…”

“…Many studies proved the induction of insulin resistance by feeding rats with HFD (Abd El-Wahab, Mohamed, El Sayed, & Bauomy, 2017;Mahfouz, Ghanem, & Mohamed, 2009;Mohamed, 2010;Shawky, Shehatou, Abdel Rahim, Suddek, & Gameil, 2014) and was established in the current study. Feeding rats with HFD for 1 and 2 months (HFD1 and HFD2, respectively) increased the hepatic insulin insensitivity as indicated by the significant elevation of serum insulin and HOMA-IR.…”