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

Abstract

The present study investigated the molecular effects of rice bran oil (RBO) on lipid-regulatory genes (sterol regulatory element binding protein-1 [Srebf1] and peroxisome proliferator-activated receptors-α [Ppara]) and the expression of catalase (CAT) and superoxide dismutase (SOD1) genes in insulin-resistant rats. Rats were divided into five groups: animals that received standard diet (control); rats fed standard diet containing RBO as the sole source of fat (RBO); a high-fructose diet (HFD) group, which was further divided into two subgroups: rats fed HFD either for only 1 month (HFD1) or for 2 months (HFD2) and rats fed HFD containing RBO for 1 month; while rats in the last group fed HFD for 30 days then treated with RBO for another 30 days. The HFD induced a state of insulin resistance (IR) as indicated by the hyperinsulinemia and elevated homeostasis model assessment insulin resistance index. Hepatic lipid levels and radical scavenging enzymes were altered by the HFD. Lipid-regulatory genes, Srebf1 and Ppara, were upregulated while Sod1 and Cat were downregulated in insulin-resistant rats. Addition of RBO to the two diet regimens alleviated the disorders of IR to some extent. RBO reduced the hepatic levels of triacylglycerol, malondialdehyde, SREBP, and PPAR-α mRNA. Hepatic SOD and CAT were elevated at gene and protein levels. The HFD induces de novo lipogenesis by upregulating the lipid-regulatory genes resulting in increased serum and hepatic triacylglycerol. Moreover, IR induced by the HFD caused a state of oxidative stress. Supplementation of RBO to fructose-fed rats not only improves insulin resistance but also downregulates lipogenic genes and improves the unbalanced oxidative status.

Rice bran oil could favorably ameliorate atherogenicity and insulin resistance indices among men with coronary artery disease: post hoc analysis of a randomized controlled trial

“…It has also been mentioned that γ-oryzanol, in addition to tocotrienols, might promote cholesterol 7-alpha-hydroxylase (CYP7A1), the enzyme with rate restriction ability in the synthesis of cholesterol, which stabilizes serum cholesterol concentration by modulating cholesterol-bile acids conversion [ 33 , 37 , 53 ]. With respect to these mechanisms, RBO has also been shown to ameliorate insulin resistance and attenuate lipotoxicity and glucotoxicity [ 32 , 35 , 37 , 43 – 46 , 48 , 54 ].…”

Rice Bran Oil Attenuates Chronic Inflammation by Inducing M2 Macrophage Switching in High-Fat Diet-Fed Obese Mice

“…Rice bran oil has previously been shown to attenuate obesity, hyperlipidemia, and inflammation in mice and rats [25,26,44]. A previous study also demonstrated that RBO exerted its anti-inflammatory effects through modulating the mitochondrial respiration of macrophages in normal diet-fed mice [27].…”

“…Rice bran oil is also known to have a balanced fatty acid composition characterized by high levels of monounsaturated oleic acid (C18:1) and polyunsaturated linoleic acid (C18:2) [22]. Previous studies have demonstrated that RBO not only alleviates hyperglycemia and hyperlipidemia but also exhibits anti-oxidant and immunomodulatory effects [22][23][24][25][26]. Recently, it was demonstrated that RBO exerts anti-inflammatory properties by upregulating the mitochondrial respiration of macrophages in a normal diet-fed mouse model [27], yet the detailed cellular mechanisms and effects of RBO on obesity-induced chronic inflammation are unclear.…”

Effect of propofol on the skeletal muscle insulin receptor in rats with hepatic ischemia-reperfusion injury

“…19 The use of antioxidants is believed to represent an effective treatment for insulin resistance. 20,21 As a commonly used intravenous anesthetic, propofol has a strong antioxidant capacity, and may improve the antioxidant capacity of red blood cells and tissues in rats. 22,23 Our study demonstrated that tyrosine phosphorylation levels of Tyr-IRb and Tyr-IRS1 in the P group were higher than those the I/R group, indicating that an improvement in insulin signaling may result in reduced hyperglycemia.…”