Background and objective: The consumption of high fat and high fructose diet (HFFD) can lead to insulin resistance and type 2 DM. We have found that hydrolysate of Jasmin rice bran could decrease insulin resistance in high fat diet-induced insulin resistant rats. Tubtim-chumphae rice is a hybrid Thai rice cultivar RD69 (กข 69 ทับทิมชุมแพ) with red colored pericarp. We aimed to investigate the effect of Tubtim-chumphae rice bran on insulin resistance in HFFD fed rats.
Methods: Hydrolysate of rice bran (HRB) was prepared using hydrothermolysis followed by enzymatic digestion. Ethanolic extract of rice bran (ERB) was prepared using 50% ethanol-water. Male Sprague-Dawley rats were fed HFFD (40% lard; 20% fructose) for 10 weeks; followed by concomitant administrations of distilled water or HRB 250 mg/kg/day or ERB 250 and 500 mg/kg/day or pioglitazone 10 mg/kg BW/day for further 4 weeks. Rats fed normal chow and distilled water was served as normal control. At the end of all treatments, fasting blood glucose (FBG); oral glucose tolerance test (OGTT); lipid profile and serum insulin were measured. Homeostatic model assessment of insulin resistance (HOMA-IR) was also evaluated.
Results: At week 14, control HFFD rats had significantly (P<0.05) high FBG, triglyceride; insulin secretion and HOMA-IR score together with impaired OGTT as compared to normal control rats. These parameters indicate the insulin resistance in HFFD rats. The administrations of HRB 250 mg/kg or ERB 250 and 500 mg/kg or pioglitazone 10 mg/kg significantly decreased FBG; triglyceride; insulin secretion and HOMA-IR score with improved OGTT as compared to HFFD control rats.
Conclusion: The results suggest that HRB and ERB improve insulin resistance in HFFD rats.