[Mechanism of electroacupuncture regulating PI3K/AKT/FoxO1 signaling pathway to improve hepatic gluconeogenesis in type 2 diabetic rats].

OBJECTIVES

To investigate the regulatory effects of electroacupuncture (EA) intervention on the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/forkhead box transcription factor O1 (FoxO1) signaling pathway and gluconeogenic function in liver tissue of type 2 diabetes mellitus (T2DM) model rats, so as to elucidate the possible mechanisms underlying EA improvement of blood glucose levels.

METHODS

Male SD rats were fed with a high-fat diet combined with intraperitoneal injection of streptozotocin to establish T2DM model. The rats were randomly divided into model, EA, and EA + LY294002 groups, with 10 rats in each group；another 10 age-matched SD rats were selected as the control group. Rats in the EA group received EA intervention at "Zusanli" (ST36) and "Neiting" (ST44) as well as acupuncture at "Weiwanxiashu" (EX-B3), once daily for 15 min each time, 6 times a week, for 4 consecutive weeks. The EA + LY294002 group received intraperitoneal injection of the PI3K inhibitor LY294002 (10 mg/kg) in addition to the EA treatment once daily, with the same intervention period with the EA group. Random blood glucose was measured using a glucometer；body weight was measured with an electronic balance；HE staining was used to observe pathological changes in liver tissue；real-time quantitative PCR was used to detect the mRNA expression levels of PI3K, AKT, FoxO1, phosphoenolpyruvate carboxykinase (PEPCK), and glucose-6-phosphatase (G6Pase)；Western blot was used to detect the protein expression levels of PI3K, p-PI3K, AKT, p-AKT, FoxO1, PEPCK, and G6Pase.

RESULTS

After treatment, compared with the control group, the model group showed significantly elevated random blood glucose levels (P<0.01), decreased body weight (P<0.01), severe liver tissue damage with enlarged hepatocytes and numerous fatty vacuoles, decreased mRNA expression levels of PI3K and AKT and reduced p-PI3K/PI3K and p-AKT/AKT protein expression ratios (P<0.01, P<0.05), and increased mRNA and protein expression levels of FoxO1, PEPCK, and G6Pase (P<0.01) in liver tissue. Compared with the model group, the EA group showed significantly decreased random blood glucose (P<0.01), increased body weight (P<0.01), improved liver pathological injury with reduced hepatocyte size and attenuated steatosis, significantly increased mRNA expression levels of PI3K and AKT and elevated p-PI3K/PI3K and p-AKT/AKT protein expression ratios (P<0.01), and decreased mRNA and protein expression levels of FoxO1, PEPCK, and G6Pase (P<0.01) in liver tissue. Compared with the EA group, the EA + LY294002 group showed elevated random blood glucose (P<0.01), decreased body weight (P<0.05), aggravated liver tissue injury, decreased mRNA expression levels of PI3K and AKT and reduced p-AKT/AKT protein expression ratio (P<0.01, P<0.05), and increased mRNA and protein expression levels of FoxO1, PEPCK, and G6Pase (P<0.01, P<0.05) in liver tissue.

CONCLUSIONS

EA at EX-B3, ST36, and ST44 can significantly reduce blood glucose levels, increase body weight, and improve liver injury in T2DM rats. The underlying mechanism may involve activation of the hepatic PI3K/AKT/FoxO1 signaling pathway, which suppresses the expression of the downstream gluconeogenic key enzymes PEPCK and G6Pase, thereby reducing hepatic glucose output.