Antidiabetic Effect Of DMDD Isolated From Averrhoa Carambola L. Roots On STZ-Induced Diabetic Mice And Its Potential Mechanism

Objectives:The present study was carried out to evaluate antidiabetic effect of DMDD isolated from Averrhoa carambola L. roots and to investigate its potential molecular mechanism on STZ-induced diabetic mice. Methods:1) Experiment was designed to investigate diabetogenic activity of STZ affected by different factors such as sex (male vs female mice), administration route (intravenously vs intraperitoneally), dose of STZ (120,150,180,200mg/kg body weight), duration of induction (3vs7days) and frequency of injection (single vs double). Symptoms accompanying diabetes mellitus such as polydipsia, polyphagia and body weight were observed every day. STZ-induced mice were considered as diabetes mellitus when fasting blood glucose level above11.1mmol/L.2) Experiment was designed to evaluate antidiabetic effect of DMDD on blood glucose levels of STZ-induced diabetic mice. DMDD was isolated using methods which have established. Diabetes induction was performed to produce diabetic mice by intravenously injection of STZ at dose of100mg/kg (single dose). Mice recording blood glucose levels more than11.1mmol/L were used and randomly divided into5groups with1group as normal. Each group consists of10mice. Group1as normal control, group2as diabetic control, group3as pioglitazone-treated diabetic, group4as12.5mg/kg DMDD-treated diabetic, group5as25mg/kg DMDD-treated diabetic, and group6as50mg/kg DMDD-treated diabetic. Treatment with pioglitazone and DMDD were conducted for15days. Blood glucose, body weight, water and food intake, FER and organ indices of liver, kidney, pancreas, adipose and spleen were determined.3) Experiment was designed to evaluate antidiabetic effect of DMDD on insulin levels and sensitivity of STZ-induced diabetic mice. Diabetes induction was performed as previous step. Insulin levels in serum and pancreas, IL-6of pancreas and IAI were determined with observation of immunohistochemistry of pancreatic islet and adipose tissue.4) Experiment was designed to evaluate antidiabetic effect of DMDD on lipid and protein metabolism of STZ-induced diabetic mice. Diabetes induction was performed as previous step. Lipid profiles in serum and tissues such as liver, kidney, and protein of serum, liver, kidney and pancreas were determined.5) Experiment was designed to evaluate antidiabetic effect of DMDD on oxidative stress of STZ-induced diabetic mice. Diabetes induction was performed as previous step. Biochemical parameters such as MDA, SOD, CAT, T-AOC, ALT, AST and ALP in serum and tissues homogenate were determined.6) Experiment was designed to evaluate antidiabetic effect of DMDD on histological changes of STZ-induced diabetic mice. Diabetes induction was performed as previous step. Histology of liver, kidney, skeletal muscle and adipose tissue were observed under light microscope.7) Experiment was designed to evaluate antidiabetic effect of DMDD on adipokines regulation of STZ-induced diabetic mice. Diabetes induction was performed as previous step. Levels of TNF-α, IL-6, leptin, resistin and adiponectin serum were determined using ELISA.8) Experiment was designed to evaluate antidiabetic effect of DMDD on mRNA and protein expression of PPAR-y in STZ-induced diabetic mice. Diabetes induction was performed as previous step. PPARy mRNA and protein were determined using RT-PCR and western blot analysis, respectively.9) Experiment was designed to evaluate antidiabetic effect of DMDD on adipocyte apoptosis of STZ-induced diabetic mice. Diabetes induction was performed as previous step. DNA fragmentation was determined by DNA laddering assay using agarose gel electrophoresis. Results:Treatment of DMDD for15days showed fasting blood glucose levels were significantly reduced on STZ-induce diabetic mice, therefore symptoms of diabetes could be alleviated. Levels of insulin also were significantly increased when compared to untreated-diabetic mice. Levels of TC, TG, LDL, VLDL, FFA, ALP, AST, and ALT were a significant decrease, whereas HDL, albumin, and total protein levels significantly increased. Oxidative stress on DMDD-treated diabetic mice could be significantly attenuated by reducing MDA levels and stimulating antioxidant activities such as SOD, CAT, and T-AOC. Abnormal histological changes in liver, kidney, pancreas, skeletal muscle and adipose tissue could be improved near to normal. Adipokine such as TNFa, IL-6, leptin and resistin were a significant decrease, whereas adiponectin increased significantly on DMDD-treated diabetic mice. DMDD up-regulated significantly mRNA and protein expression of PPARy, but no DNA fragmentation observed after treated by DMDD. Conclusions:DMDD evidently possessed antidiabetic affect and up-regulated PPARy expression. Potential mechanism by which DMDD lowered hyperglycemia might be associated with its ability to induce PPARy-mediated insulin secretion and sensitivity, via stimulating free fatty acid storage, promoting antioxidant activity, modulating adipocyte hormones and protecting tissues damage.