Objective: To explore the molecular mechanism underpinning the action by investigating its effect on glycogen content and AKT (also known as protein kinase B)/glycogen synthase kinase 3β (GSK- 3β) pathway in the liver of rats with type 2 diabetic induced by high-fat diet.
Methods: The rat model of type 2 diabetes was induced by high-fat diet and multiple low-dose streptozotocin injection. Diabetic rats were divided into five groups: the model control group, the Metformin group, spleen-kidney supplementing formula groups of low, medium and high doses. Fasting blood glucose (FBG) levels were measured before treatment and every two weeks during treatment. After the treatment, oral glucose tolerance test was performed, and hemoglobin A1c (HbA1c) and C-peptide were measured to assess the formula's effect on glucose metabolism and insulin resistance. The protein expression levels of AKT, GSK-3β and their phosphorylated forms in the liver were also measured to study the formula's role in insulin signaling pathway.
Results: Spleen-kidney supplementing formula significantly relieved the symptoms of polydipsia, polyuria and weight loss in type 2 diabetic rats, reduced FBG and HbA1c levels, increased glycogen content, and improved insulin sensitivity. The anti-diabetic effects of spleen-kidney supplementing formula are dose dependent. It also increased the total AKT protein level and the GSK-3β phosphorylation in the liver of type 2 diabetic rats.
Conclusion: Spleen-kidney supplementing formula has hypoglycemic effect and relieves insulin resistance by enhancing AKT/GSK-3β signaling pathway in the liver of type 2 diabetic rats.
Keywords: Glycogen; Insulin resistance; Phosphorylation; Proto-oncogene proteins c-akt; Spleen-kidney supplementing formula.