Effect of Riceberry oil (deep purple oil; Oryza sativa Indica) supplementation on hyperglycemia and change in lipid profile in Streptozotocin (STZ)-induced diabetic rats fed a high fat diet

Abstract

Riceberry oil (RBBO) has been described as having a high level of antioxidants and functional properties. The aim of the present study was to determine the effects of RBBO on changes in blood glucose, insulin levels, and GLUT4 transporter as well as lipid profiles in Streptozotocin (STZ) - induced hyperglycemic rats fed a high-fat diet. Seventy male Sprague-Dawley rats, aged six weeks and weighing 196.09 ± 10.46 g, were randomly divided into two groups: the first group of 20 rats was fed with a basal diet and another group of 50 rats were fed with a high fat (HF) diet. After two weeks, rats fed the HF-diet were induced to hyperglycemia by two doses of STZ injections (20 and 30 mg/kg; i.p.). Normal rats were divided into two groups: one group fed with basal diet (NC) and another group fed with basal diet with the oil source replaced with 5% RBBO (NR). Diabetic rats were randomized into five groups of 10 rats each as follows: untreated diabetic rats (DMC) fed a high fat (HF) diet alone; and 4 treated groups fed with high fat + 5% RBBO (DMRL); HF + 7.5% RBBO (DMRM); HF + 15% RBBO (DMRH); and HF + metformin 300mg/kg BW (DM-MET), respectively. All rats were given free access to their diet and water for 12 weeks. After 12 weeks of supplementation, significant improvement of blood glucose, insulin, HbA1C, intraperitoneal glucose tolerance and GLUT 4 transporter level were observed in the RBBO supplemented groups compared to the DMC group. Significant reductions in TC, LDL-cholesterol, TG and TG/HDL ratio were also shown in rats fed with RBBO when compared to those of diabetic rats. Findings in the present study demonstrate that RBBO, a nutraceutical food, may be useful as an alternative food supplement for the alleviation of hyperglycemia and dyslipidemia conditions.