Obesity is a leading global health problem contributing to various chronic diseases, including type II diabetes mellitus (T2DM). The aim of this study was to investigate whether blueberries, yoghurt, and their respective bioactive components, Cyanidin-3-O-β-glucoside (C3G) and peptides alone or in combinations, alter the expression of genes related to glucose metabolism in skeletal muscles from diet-induced obese mice. In extensor digitorum longus (EDL), yoghurt up-regulated the expression of activation of 5’adenosine monophosphate-activated protein kinase (AMPK), insulin receptor substrate-1 (IRS-1), phosphatidylinositol-3 kinase (PI3K) and glucose transporter 4 (GLUT4), and down-regulated the expression of angiotensin II receptor type 1 (AGTR-1). The combination of blueberries and yoghurt down-regulated the mRNA expression of AGTR-1 and Forkhead box protein O1 (FoxO1) in the EDL. Whereas the combination of C3G and peptides down-regulated AGTR-1 and up-regulated GLUT4 mRNA expression in the EDL. In the soleus, blueberries and yoghurt alone, and their combination down-regulated AGTR-1 and up-regulated GLUT4 mRNA expression. In summary blueberries and yoghurt, regulated multiple genes associated with glucose metabolism in skeletal muscles, and therefore may play a role in the management and prevention of T2DM.

Following the eight week treatment period, the mice were deeply anaesthetised using isoflurane. Soleus and the EDL were collected into cryotubes and immediately frozen in liquid nitrogen for RNA analysis.

RNA was extracted from the soleus and the EDL utilising a TRIzol based method according to the manufacturer’s instruction. Total RNA (0.5 μg) was reverse transcribed into cDNA using the iScriptTM cDNA Synthesis Kit, according to manufactures instructions.

Oligonucleotide primers were designed using the Oligoperfect™ Suite (Invitrogen, Victoria, Australia) and were purchased from Integrated DNA Technologies, Inc. (Coralville, Iowa). The primer sequences used for the genes of interest are detailed in Table 1. ‘Real Time’ PCR was utilised using SYBR Green Supermix and MyiQ™ multiplex ‘real-time’ PCR detection system (Bio-Rad Laboratories, Hercules, CA). Relative changes in mRNA abundance was normalised to the average of the housekeeping gene, hypoxanthine phosphoribosyltransferase 1 (HPRT-1), then quantified using the 2-ΔΔCTmethod.

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