Pumpkin polysaccharide modifies the gut microbiota during alleviation of type 2 diabetes in rats

Pumpkin polysaccharide is able to alleviate diabetes, but understanding of the underlining mechanism is still limited. In this study, we hypothesized that the alleviating effects of pumpkin polysaccharide is modulated via changes in the gut microbiota and short-chain fatty acid (SCFA) production in type 2 diabetic rats. After the type 2 diabetic model successfully was established, three groups of high-fat diet induced diabetic rats were intragastrically administered pumpkin polysaccharide, metformin, or saline solution respectively. We utilized 16S rRNA gene sequencing and multivariate statistics to analyze the structural and key species of gut microbiota in the type 2 diabetic rats. The results revealed that pumpkin polysaccharide alleviated the type 2 diabetes by improving the insulin tolerance and decreasing the levels of serum glucose (GLU), total cholesterol (TC), and low-density lipoprotein (LDL-C), while increasing the levels of high-density lipoprotein (HDL-C). Simultaneously, pumpkin polysaccharide changed the structure of gut microbiota and had selective enrichment in key species of Bacteroidetes, Prevotella, Deltaproteobacteria, Oscillospira, Veillonellaceae, Phascolarctobacterium, Sutterella, and Bilophila. The correlations between the key species and SCFA production indicated the underlining mechanisms of pumpkin polysaccharide on type 2 diabetes.