Hepatic Glucose Regulations by Sago (Metroxylon sagu) Resistant Starch in Diabetic Goto Kakizaki Rat

Abstract

Resistant starch (RS) Sago (Metroxylon sagu) intake has been linked with the improvement in postprandial hyperglycemia and diabetes management via several modes of action including delayed glucose absorption and inhibition of carbohydrate digestion in the gastrointestinal tract. However, to our knowledge, studies on local Malaysian sago RS associated with hepatic glucose production has not been reported elsewhere. Thus, this study was done to identify the underlying mechanisms of local Malaysian RS sago native and modified known as sago RS type 2 (sago RS2) and type 4 (sago RS4) respectively in glucose regulations by analyzing the targeted genes in hepatic glucose pathways. In this study, gene expression associated with Glucose and Glycogen Metabolism Pathways analysis in the liver of spontaneously type 2 diabetic rat, Goto kakizaki treated with water (control), Hi Maize (positive control), sago RS2 and RS4 was done using Rat Glucose Metabolism RT² Profiler PCR Array which consist of 84 genes. The results showed that several genes were significantly up- and down-regulated in the diabetic rats treated with Sago. Taldo1 was significantly upregulated whereas G6PC, Sdhb and Rplp1 genes were significantly downregulated in the rat liver treated with sago RS2. In the rat liver treated with sago RS4, Idh3g gene was significantly upregulated whereas G6pc, Pdk3, Eno3, Sdhb, Galm and Tkt genes were significantly downregulated. The gene expressions identified are associated in the blood glucose homeostasis involving the regulation and enzymatic pathways of glucose and glycogen metabolisms. In conclusion, the genes identified might be useful for therapeutic targets in glucose lowering effects by reducing hepatic glucose output indicating potential of our local sago in managing diabetes.