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BackgroundThe fruiting body of Ganoderma lucidum has been used as a traditional herbal medicine for many years. However, to the date, there is no detailed study for describing the effect of G. lucidum spores on oxidative stress, blood glucose level and lipid compositions in animal models of type 2 diabetic rats, in particular the effect on the gene expression profiles associated with glucose and lipid metabolisms.MethodsG. lucidum spores powder (GLSP) with a shell-broken rate >99.9 % was used. Adult male Sprague–Dawley rats were randomly divided into three groups (n = 8/group). Group 1: Normal control, normal rats with ordinary feed; Group 2: Model control, diabetic rats with ordinary feed without intervention; Group 3: GLSP, diabetic rats with ordinary feed, an intervention group utilizing GLSP of 1 g per day by oral gavages for 4 consecutive weeks. Type 2 diabetic rats were obtained by streptozocin (STZ) injection. The changes in the levels of glucose, triglycerides, total cholesterol and HDL-cholesterol in blood samples were analyzed after GLSP intervention. Meanwhile, gene expressions associated with the possible molecular mechanism of GLSP regulation were also investigated using a quantitative RT-PCR.ResultsThe reduction of blood glucose level occurred within the first 2 weeks of GLSP intervention and the lipid synthesis in the diabetic rats of GLSP group was significantly decreased at 4 weeks compared to the model control group. Furthermore, it was also found that GLSP intervention greatly attenuated the level of oxidative stress in the diabetic rats. Quantitative RT-PCR analysis showed up-regulation of lipid metabolism related genes (Acox1, ACC, Insig-1 and Insig-2) and glycogen synthesis related genes (GS2 and GYG1) in GLSP group compared to model control group. Additionally, there were no significant changes in the expression of other genes, such as SREBP-1, Acly, Fas, Fads1, Gpam, Dgat1, PEPCK and G6PC1.ConclusionThis study might indicate that GLSP consumption could provide a beneficial effect in terms of lowering the blood glucose levels by promoting glycogen synthesis and inhibiting gluconeogenesis. Meanwhile, GLSP treatment was also associated with the improvement of blood lipid compositions through the regulation of cholesterol homeostasis in the type 2 diabetic rats.Electronic supplementary materialThe online version of this article (doi:10.1186/s12944-015-0045-y) contains supplementary material, which is available to authorized users.

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Recent studies have revealed that diabetes mellitus caused gut bacterial dysbiosis, and intervention studies aiming to selectively alter the composition and metabolism of the gut microbiota are crucial next steps for investigating the links between the microbiome and diabetes. The sequences encompassing V1-3 16S rDNA hypervariable regions were PCR amplified from rat fecal samples fed with resistant starch (RS). In total, 13 different phyla and 107 different genus were obtained with a 3% distance cut off. The microbiota profile of normal rats was significantly different from that of rats in diabetic control and RS intervention group. The most prominent phyla were Firmicutes and Bacteroidetes in the three groups. The proportion of Proteobacteria was significantly higher in the rats of diabetic control compared to normal group, and RS intervention could inhibit the proliferation of Proteobacteria phyla, including a wide variety of pathogenic species, such as Escherichia-Shige, Klebsiella, and Pseudomona. At genus level, Lactobacillus in the diabetic control was significantly lower than that in the normal group, whereas the feeding of RS increased the amount of Lactobacillus. More importantly, the consumption of RS reduced the composition of Ruminococcus and increased S24-7 norank comparing with the diabetic control. This study might indicate that RS is an effective food ingredient for manipulating the gut microbiota.