Diabetes mellitus is a clinically complex disease characterized by chronic hyperglycemia with metabolic disturbances. In this study, we investigated the effect of mulberry leaf polysaccharide (MLPII) on pancreatic islet cell
apoptosis and insulin secretory function in diabetic rats induced by a high fat diet and streptozotocin. Our results
showed that MLPII treatment inhibited pancreatic islet cell apoptosis and ameliorated insulin secretory capacity
of pancreaticβ-cells in diabetic rats. And further study demonstrated that chronic treatment of diabetic rats with
MLPII resulted in up-regulation of anti-apoptotic B-cell leukaemia/lymphoma 2 (Bcl-2) protein and downregulation of pro-apoptotic Bcl2-associated X (Bax) and caspase-3 protein in pancreatic islet cells. Moreover,
MLPII significantly restored pancreatic duodenal homeobox-1 (PDX-1) protein nuclear localization, and increased mRNA and protein expression of PDX-1 and its downstream targets, glucose transporter 2 (GLUT2)
and glucokinase (GCK) in pancreatic islet cells of diabetic rats. Thesefindings suggested that MLPII might play
a critical role in protecting pancreatic islet cell from apoptosis via elevation of Bcl-2/Bax ratio, and ameliorating
insulin secretory capacity of pancreaticβ-cells via restoration of PDX-1 nuclear localization and expression levels
in diabetic rats. This is thefirst report to explore the potential molecular mechanism involved in the hypoglycemic activity of the polysaccharide from mulberry leaves