Acupuncture intervention induced improvement of oxidative stress by regulating PKCβ/P66shc signaling in obese diabetic rats

Abstract

To observe the effect of electroacupuncture (EA) at "Zusanli"(ST36)-"Sanyinjiao"(SP6) on glucose and lipid metabolism and insulin resistance (IR) in obese diabetic rats, so as to explore its mechanism underlying improvement of obesity diabetes. SPF male rats were randomly divided into normal control, model, meridian-acupoint EA (acupoint), non-meridian non-acupoint EA (non-acupoint), and medication (metformin) groups, with 10 rats in each group. The diabetes model was established by feeding the rats with high-fat diet for 8 weeks. EA (1.5 mA, 10 Hz/100 Hz) was applied to unilateral ST36 and SP6 for 20 min, once daily (except Sundays) for 4 weeks. Rats of the medication group were treated by gavage of metformin (300 mg/kg) once daily for 4 weeks (except Sundays). The body weight and length were measured and the Lee's index was calculated. The contents of total cholesterol (TC), triglyceride (TG), low density lipoprotein-cholesterol (LDL-C), high density lipoprotein-cholesterol (HDL-C) in the plasma were detected by using a full-automatic biochemical analyzer. The content of fasting serum insulin (FINS) was assayed by using radioimmunoassay, the fasting blood glucose (FBG) was measured, and serum superoxide dismutase (SOD) activity by using xanthine oxidase method, serum malondialdehyde (MDA) by color method, serum glutathione peroxidase (GSH-Px) activity by indirect method, reactive oxygen species (ROS) by Dithio-bis-nitrobenzoic acid (DTNB) direct method, and the homeostasis model assessment of IR (HOMA-IR) and insulin sensitive index (ISI) were calculated. The expression levels of pancreatic tissue P66shc mRNA and PKCβ mRNA were detected by using RT-PCR, and the histopathological changes of the liver and adipose tissues were observed after H.E. staining. Compared with the normal control group, the Lee's index, levels of FBG, FINS, HOMA-IR, TC, TG, LDL-C, MDA, ROS, and P66shc mRNA and PKCβ mRNA expressions were significantly increased (P<0.05，P<0.01), and ISI, HDL-C, SOD, GSH-Px significantly decreased (P<0.05, P<0.01) in the model group. After the interventions, the levels of Lee's index,levels of FBG, FINS, HOMA-IR, TC, TG, LDL-C, MDA, ROS, and expressions of P66shc mRNA and PKCβ mRNA were remarkably down-regulated (P<0.05, P<0.01), and those of ISI, HDL-C, SOD, and GSH-Px up-regulated (P<0.05, P<0.01) in both EA and medication groups. H.E. staining showed many white adipocytes in the adipose tissue, radial and cord-like arrangement of liver cells, and many of them with vacuoles in the cytoplasm of small vesicular lipid droplets in the model group; and relative reduction of white adipocytes in number, smaller in cell body, and no obvious abnormal changes of structure and arrangement of liver cells in the EA and medication groups. EA of ST36 and SP6 can improve glucose and lipid metabolism and IR in obese diabetic rats, which may be related to its function in suppressing PKCβ/P66shc signaling and oxidative stress.