Headings ethnopharmacological relevance: Portulaca oleracea L. is a succulent annual herb, which has various pharmacological effects including antidiabetic property. However, in vivo the reducing effect of P. oleracea on hyperglycemia and its mechanism of action have not been clarified in a mouse model of type 2 diabetes.
Aim of the study: The effects of Portulaca oleracea L. extract (POE) on hyperglycemia were investigated in an animal model of type 2 diabetes.
Materials and methods: C57BL/Ksj-db/db mice were randomly divided into three groups: db/db-control group was fed a standard semi-synthetic diet (AIN-93 G), db/db-RG group was fed AIN-93 G supplemented with rosiglitazone (RG) (0.005%, w/w), and db/db-POE group was fed AIN-93 G supplemented with POE (0.4%, w/w) for 6 weeks. Diabetes-related physical and biochemical indicators and the phosphorylation of components of PI3k/Akt and AMPK pathways were measured.
Results: The blood glucose and the glycosylated hemoglobin levels (HbA1c) in db/db-POE group were significantly lower than those in db/db-control group. In db/db-POE group, The homeostatic index of insulin resistance (HOMA-IR) decreased significantly, whereas the quantitative insulin sensitivity check index (QUICKI) was higher than those in db/db-control group. POE significantly elicited the phosphorylation of IRS-1Tyr612, AktSer473, and AS160Thr642, and the activation of PI3K in the skeletal muscle of mice. Additionally, POE significantly stimulated the phosphorylation of AMPKThr172, TBC1D1Ser231, and ACCSer79 and elevated the expression of plasma membrane-glucose transporter type 4 (GLUT4).
Conclusions: These results indicate that POE reduces hyperglycemia by improving insulin resistance through the PI3k/Akt and AMPK pathways in the skeletal muscle of C57BL/Ksj-db/db mice.
Keywords: Db/db mice; Hyperglycemia; Insulin resistance; Portulaca oleracea; Skeletal muscle.
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