Effects of endurance exercise and ginsenoside RB1 on AMP-activated protein kinase, phosphatidylinositol 3-kinase expression and glucose uptake in the skeletal muscle of rats

This study investigated the effects of endurance exercise and ginsenoside Rb₁ on AMP-activated protein kinase (AMPK), phosphatidylinositol 3-kinase (PI3K) protein expression and glucose uptake in the skeletal muscle of rats. A total of 32 rats were randomly divided into four groups: CON (Control group, n=8), Ex (Exercise group; 25 m/min for 1 h, 6 days/week, 2 weeks, n=8), Rb₁ (Ginsenoside Rb₁ group; n=8), and Rb₁/Ex (Rb₁+Exercise group, n=8). The Rb₁ and Rb₁/Ex groups were incubated in ginsenoside Rb₁ (KRBP buffer, 100 μg/mL) for 60 min after a 2-week experimental treatment. After 2 weeks, the expression of phosphorylated AMPKα Thr¹⁷², total AMPKα, the p85 subunit of PI3K, pIRS-1 Tyr⁶¹², and pAkt Ser⁴⁷³ were determined in the soleus muscle. Muscle glucose uptake was measured using 2-deoxy-D-[3H] glucose in epitroclearis muscle. Muscle glucose uptake was significantly higher in the three experimental groups (Ex, Rb₁, Rb₁/Ex) compared to the CON group (P<0.05). The expression of tAMPKα and pAMPKα Thr¹⁷² was significantly higher in the Ex, Rb₁, and Rb₁/Ex groups compared to the CON group (P<0.05). The expression of pAkt Ser⁴⁷³ was significantly higher in the Rb₁ group compared to the CON and EX groups. However, the expression of pIRS-1 Tyr⁶¹² and the p85 subunit of PI3K were not significantly different between the four groups. Overall, these results suggest that ginsenoside Rb₁ significantly stimulates glucose uptake in the skeletal muscle of rats through increasing phosphorylation in the AMPK pathway, similar to the effects of exercise.