The Effect Of Auricularia On Type 2 Diabetes Mellitus And Its Mechanism

Gynurae Cusimbuae is a herb of Gynura cusimbua (D. Don) S. Moore. G. cusimbua was applied to fracture, injuries and rheumatoid arthritis in the Yi and LahuNationality Traditional Medicines in China. According to other literatures, other plants of this species, such as Gynura procumbens?Gynura bicolor?Gynura divaricata and Gynura medica, are very helpful to reduce the blood-glucose. Our previous researches showed G. cusimbua may have hypoglycemic effects via mechanisms of a-glucosidase inhibition. In our study, we prepared to observe the effect of G. cusimbua on Type 2 diabetes.In this research, we prepared GCTE (Total extract from Gynurae cusimbuae, GCTE); observed the effect of GCTE on L6 cells' glucose uptake and Type 2 diabetes mice's FBG?OGTT?serum insulin?body weight; researched the possible mechanism of improving insulin resistance on cell and tissue respectively, providing comprehensive theoretical basis for Gynurae Cusimbuae's further development and application.The main research methods and results were as follows:(1) MTT assay was used to cytotoxicity test of L6 cells. The result showed that 20% inhibitive concentration (IC20) and 50% inhibitive concentration (IC50) of GCTE were 0.7?1.6 mg/mL, respectively. So in this study, we chose 0.2? 0.6mg/mL as the subsequent concentration.(2) Builded L6 cells insulin resistance model inducing by a certain concentration of PA; GCTE was used to intervene and as the experimental group; glucose oxidase method was used to detect the glucose concentration of cell culture fluid. The results showed that the model group had lower glucose consumption comparedwith the normal group (P<0.01); GCTE low and high dose group can make higher glucose consumption than model group (P<0.05, P<0.01)(3) Builded Type 2 diabetic model by injecting a little streptozotocin and raising high-fat-sugar die to mice. The results showed that diabetic mice model have some symptoms, such as polyuria, polydipsia, polyphagia; the FBG (Fasting Blood Glucose) of the model group was clearly higher than the normol group (P<0.01), which illustrate that type 2 diabetic model was established. The FBG of the GCTE low and high dose group were 12.61 mmoL/L?13.41mmoL/L respectively, and were lower compared with the model group(P<0.01).(4) Detected the levels of serum insulin by Elisa method. The results showed that the concentration of serum insulin in the model group was higher than the normal group (P<0.01), and the insulin sensitivity index was smaller; Diabetic mice treating with GCTE had a lower concentration of serum insulin and larger insulin resistance index.(5) Observed OGTT of diabetic mice by detecting FBG on regular time. The results showed that, the model group had a higher bloodglucose after 0.5h of diner, and reached the peak after 2h of diner. The GCTE groups also had a higher blood-glucose, but reach the peak only after 1h of diner and have a lower blood-glucose 2h later.(6) Detected the levels of mice serum LDL?HDL by direct method; Detected the levels of mice serum GC?TC by COD-PAP?GPO-PAP method respectively. The results showed that the LDL?GC?TC concentration of the model group was higher than the normal group, however, the HDL concentration was lower. The concentration of LDL?GC?TC were decreased and the concentration of HDL was increased when the mice were treated with GCTE.(7) The expression level of GLUT4 mRNA in skeletal muscle and L6 cells was detected by RT-PCR. The results showed that the GLUT4 mRNA relative abundance of the model group was lower than the normal group, but the relative abundance of GLUT4 mRNA was increased when the mice were treated with GCTE.(8) The expression level of GLUT4, IRS-1 proteins in skeletal muscle and L6 cells were detected by western blot method. The results showed that the expression level of GLUT4? IRS-1 proteins in the model group were lower than the normal group, but the expression level of GLUT4, IRS-1 proteins were increased when the mice were treated with GCTE.The results suggested that GCTE could increase the GLUT4 expression by activating the PI3-Akt signaling pathway.(9) The expression level of GLUT4 proteins in cell membrane of skeletal muscle and L6 cells were detected respectively by western blot method. The results showed that the expression level of GLUT4 protein in the model group were lower than the normal group, but the expression level of GLUT4 protein were increased when the mice were treated with GCTE.Conclusion:GCTE could effectively improve insulin resistance in L6 cells and mice, activate the PI3-AKt signaling pathway, promote the expression level of GLUT4 mRNA and GLUT4, IRS-1 proteins, and accelerate the translocation of GLUT4. The results indicated that G.Cusimbuae may be the potential agent to diabetes mellitus.