Protective Effects Of African Potato On Skeletal Muscle Of Diabetic Rats And Regulation Of AMPK Signaling

Diabetes Mellitus (DM) is a medical condition of several metabolic disorders caused by genetic and environmental factors and marked by clinical performance of glucose metabolic disorders. DM has high morbidity and mortalilty in the world. It is a great threat to global health. The treatment and mechanism research of diabetes is becoming a hot spot. Traditional medicine has a long history and plays an important role in the global current medical service system. Prevention and treatment of DM using natural plant medicine is rich in experience and effective in clinical effect. Hypoxis Hemerocallidea (African Potato, AP), considered a very potential plant medicine to treat modern diseases, is one of the most commonly used traditional herbal medicine in South Africa and used to treat diseases such as diabetes, high blood pressure, prostate cancer. The curative effect of AP treating diabetes is significant, but the mechanism is still not clear. It hasn’t been reported if AP can improve skeletal muscle insulin resistance. This project uses DM rats and C2C12 skeletal muscle cells as insulin resistance model to explore the mechanism of AP on rats’skeletal muscle about insulin resistance.Objective:Use high fat feed and Streptozotocin(STZ) to induce DM rat models and C2C12 insulin resistance model to observe the effect of AP on skeletal muscle insulin resistance, oxidative stress, AMPK pathway. Explore the prevention and cure effect of AP on DM and provide experimental basis for the treatment of DM.Materials and Methods:1 In vivo experiment:40 male SD rats were included with 10 remained in the normal group and 30 were high-fat feeding for a month, then injected with STZ. After successfully modeled to be DM rats, they were divided into control group, pioglitazone hydrochloride group and AP group. Received gavage for five weeks, body weight and fasting blood glucose measured every week, OGTT tested every two weeks, GLU, TG, TC, HDL, LDL of serum were tested after sacrificed. Imbed and slice the skeletal muscle tissue for HE staining, immunohistochemistry, TUNEL test, SOD test, MDA test. Detect protein and mRNA of MnSOD, p-AMPK, p-AS16, GLUT4, NF-kb mRNA in skeletal muscle using Western blot and RT-PCR.2 In vitro experiment:C2C12 skeletal muscle cells insulin resistance model was set up by 100mmol/L glucose. Use AP drug-containing serum for 24h as treatment group and normal cells as control group. Glucose consumption, cell proliferation, SOD content, MDA content were detected and the protein、mRNA of p-AMPKα、AS160、p-AS160、GLUT4were detected using Western blot and RT-PCR.Results:1 In vivo experiment:There is no statistical difference of body weight of each group compared with normal group. The serum GLU, TG and LDL were significantly lower (P<0.05) after treatment. Tunel detection results show that AP treatment could reduce the degree of skeletal muscle apoptosis. AP significantly increased SOD, MnSOD content (P<0.05) and decreased MDA content (P<0.01). The protein and gene expressions of MnSOD、GLUT4 also increased (P<0.05). AP could also up-regulate p-AMPKa protein express (P<0.01), skeletal AS160 phosphorylation level(P<0.01), GLUT4(P<0.01), and reduce the gene expression of NF-kb.2 In vitro experiment:Compared with normal group, glucose caused the fall of C2C12 skeletal muscle cell activity and glucose consumption (P<0.05). After the intervention of AP drug-containing serum for 48h, MDA content were significantly decreased (P<0.05). AP drug-containing serum also increased p-AMPK, P-AS160 protein express (P<0.01), GLUT4 (P<0.05).Conclusions:1 AP can significantly decrease blood glucose and blood lipid level of DM rats and has the effect of treating diabetes.2 AP can improve oxidative stress in diabetic rats skeletal muscle and inhibit its cell apoptosis.3 AP can increase glucose induced C2C12cells activity and glucose consumption and inhibit its oxidative stress state.4 AP may improve insulin resistance of skeletal muscle by regulating AMPK-AS 160 phosphorylation and increase the expression of GLUT4.