Effects of Red Rice Bran Extract on High-Fat Diet-Induced Obesity and Insulin Resistance in Mice

Narongsuk Munkong; Arthid Thim-Uam; Sirinat Pengnet; Pintusorn Hansakul; Nuntiya Somparn; Jarinyaporn Naowaboot; Jiraporn Tocharus; Chainarong Tocharus

doi:10.3746/pnf.2022.27.2.180

Effects of Red Rice Bran Extract on High-Fat Diet-Induced Obesity and Insulin Resistance in Mice

Prev Nutr Food Sci. 2022 Jun 30;27(2):180-187. doi: 10.3746/pnf.2022.27.2.180.

Authors

Narongsuk Munkong¹, Arthid Thim-Uam², Sirinat Pengnet³, Pintusorn Hansakul⁴, Nuntiya Somparn⁴, Jarinyaporn Naowaboot⁴, Jiraporn Tocharus⁵, Chainarong Tocharus⁶

Affiliations

¹ Department of Pathology, School of Medicine, University of Phayao, Phayao 56000, Thailand.
² Division of Biochemistry, School of Medical Sciences, University of Phayao, Phayao 56000, Thailand.
³ Division of Physiology, School of Medical Sciences, University of Phayao, Phayao 56000, Thailand.
⁴ Department of Preclinical Science, Faculty of Medicine, Thammasat University, Pathum Thani 12120, Thailand.
⁵ Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand.
⁶ Department of Anatomy, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand.

Abstract

Insulin resistance is a salient player in the pathogenesis of obesity and its related abnormal glucose-insulin homeostasis. Red rice bran extract (RRBE) demonstrates several bioactive phytochemicals with anti-diabetic properties. However, little is known about its molecular mechanisms. Therefore, the present study was designed to investigate the anti-insulin resistant mechanisms of RRBE in a model of high-fat diet (HFD)-induced insulin resistance. In this study, mice were randomly divided into four groups: low-fat diet with distilled water (Group L), HFD with distilled water (Group H), HFD with 0.5 g/kg RRBE, and HFD with 1 g/kg RRBE. Metabolic parameters, histological changes in the pancreas, and gene expression levels were evaluated after treating HFD-fed mice with RRBE for six weeks. Mice from Group H exhib-ited significantly higher blood glucose levels prior to and after an oral glucose tolerance test, fasting serum insulin levels, islet size, pancreatic insulin expression levels, and lower skeletal muscle insulin-degrading enzyme (IDE) expression levels compared to Group L. In contrast, these were all significantly restored in the RRBE-treated groups. Also, RRBE treatment was found to upregulate the expression of insulin receptor substrate (IRS) and glucose transporter (GLUT) genes in the adipose tissues and GLUT genes in the muscles and livers of HFD-fed mice. According to our results, RRBE may ameliorate abnormal glucose-insulin metabolism by modulating the expression of insulin, IDE, IRS, and GLUT genes in the major metabolic target tissues of mice after being fed with HFD.

Keywords: hyperglycemia; hyperinsulinemia; insulin resistance; obesity; red rice bran.