Novel synergic antidiabetic effects of Astragalus polysaccharides combined with Crataegus flavonoids via improvement of islet function and liver metabolism

The present study investigated the synergic effects and potential mechanisms of action of Astragalus polysaccharides (APS) combined with Crataegus flavonoids (CF) in the treatment of type 1 diabetes. Diabetes was induced by intraperitoneal injection of 100 mg/kg streptozotocin in mice. Normal and untreated diabetic control mice were used, and CF-treated (200 mg/kg/day), APS-treated (200 mg/kg/day), APS + CF (AC)-treated (200 mg/kg/day of each) and metformin-treated (200 mg/kg/day) diabetic mice were orally administrated the appropriate therapeutic agent for 4 weeks. The results demonstrated that AC treatment significantly reduced the fasting blood glucose, food and water intake in the diabetic mice. The AC group demonstrated increased serum insulin levels and islet cell function was restored. Furthermore, the AC-treated mice demonstrated significant increases in the protein expression levels of pancreatic and duodenal homeobox-1 and phosphorylated adenosine 5-monophosphate-activated protein kinase in the pancreatic and liver tissue samples, respectively. In addition, AC significantly increased the mRNA expression levels of neurogenin 3, v-maf musculoaponeurotic fibrosarcoma oncogene family, protein A and insulin, and simultaneously decreased the expressions of interleukin 6, tumor necrosis factor- and chemokine (C-C motif) ligand 2 in the pancreatic islet cells of diabetic mice. The anti-inflammatory activity of APS and the islet-restoring effect of CF may contribute to the improvement of islet function. AC exerted greater antidiabetic effects compared with APS or CF treatments alone. These results indicated that AC treatment had a synergic antidiabetic effect, which may involve improvements in islet function and liver metabolism. These effects of AC may facilitate the treatment of type 1 or 2 diabetes, as these patients frequently experience impaired islet function and disordered extrapancreatic metabolism.