Rice Bran Protein Hydrolysates Improve Insulin Resistance and Decrease Pro-inflammatory Cytokine Gene Expression in Rats Fed a High Carbohydrate-High Fat Diet

Abstract

A high carbohydrate-high fat (HCHF) diet causes insulin resistance (IR) and metabolic syndrome (MS). Rice bran has been demonstrated to have anti-dyslipidemic and anti-atherogenic properties in an obese mouse model. In the present study, we investigated the beneficial effects of rice bran protein hydrolysates (RBP) in HCHF-induced MS rats. After 12 weeks on this diet, the HCHF-fed group was divided into four subgroups, which were orally administered RBP 100 or 500 mg/kg, pioglitazone 10 mg/kg, or tap water for a further 6 weeks. Compared with normal diet control group, the MS rats had elevated levels of blood glucose, lipid, insulin, and HOMA-IR. Treatment with RBP significantly alleviated all those changes and restored insulin sensitivity. Additionally, RBP treatment increased adiponectin and suppressed leptin levels. Expression of Ppar-γ mRNA in adipose tissues was significantly increased whereas expression of lipogenic genes Srebf1 and Fasn was significantly decreased. Levels of mRNA of proinflammatory cytokines, Il-6, Tnf-α, Nos-2 and Mcp-1 were significantly decreased. In conclusion, the present findings support the consumption of RBP as a functional food to improve insulin resistance and to prevent the development of metabolic syndrome.

Fermented rice bran supplementation mitigates metabolic syndrome in stroke-prone spontaneously hypertensive rats

“…Both glucose and insulin are potent factors that are involved in inducing the transcription of key enzyme genes in glycolysis and de novo lipogenesis [34]. It has been found that rice bran derivatives reduce plasma and liver lipids, whereas protein hydrolysates from rice bran improve insulin and leptin sensitivity in high-fat diet-induced metabolic syndrome in hamsters [6, 14]. Insulin triggers the transcriptions of glycolytic and lipogenic enzymes by activating SREBP-1c and LXRα [35, 36].…”

“…Enzyme-treated rice bran has been shown to be effective against chronic diseases in rat and mouse models [12, 13]. For instance, a recent study showed that protein hydrolysates from rice bran improved insulin resistance in a mouse model [14]. Emerging evidence of the chronic disease-fighting properties of rice bran has advanced the development of rice bran for human use as a functional food and a dietary supplement [15].…”

Rice Bran as a Functional Food: An Overview of the Conversion of Rice Bran into a Superfood/Functional Food

“…Interestingly, the antidiabetic and antidyslipidemic activities of rice bran have been reported in different animal model experiments [15][16][17]. Furthermore, the active components in processed rice bran promote health; indeed, the processing itself adds value to the rice bran [18,19].…”

An Animal Study to Compare Hepatoprotective Effects Between Fermented Rice Bran and Fermented Rice Germ and Soybean in a Sprague-Dawley Rat Model of Alcohol-Induced Hepatic Injury

“…Rodent models have demonstrated its efficacy against chronic diseases when treated with enzymes [27,28]. The effect of protein hydrolysates from RB in improving insulin resistance is one of the best examples in this case [29]. Thus, there is a growing evidence of the potential effects of RB in treating chronic diseases and their application to human health [30].…”