| Objective:Observe the effects of a-lipoic acid on the activity of AMPK in the diabetic rats induced by streptozotocin, to research the different regulation effects of a-lipoic on the AMPK in different tissue and the role of AMPK in improving the metabolism turbulance in diabetes rats, and provide the new acting targets for metabolic disease such as diabetes and obesity.Methods:Fifty healthy male Wistar rats(weighing180-200g) were randomly divided into two groups after adaptive feeding with ordinary food for7days, the normal control group(NC n=15) and the experimental group (EG n=35). The rats of NC group were continued to feed with primary diet while the rats of experimental group were switched to high fat diet, then at the end of the4th weeks those rats of EG were gived STZ (30mg/kg) intraperitoneal injection singly after overnight fasting12hours which was dissolved in O.1mol/L citric acid-citrate sodium buffer (pH4.2), and the NC were injected with the same amount of citric acid-citrate sodium buffer only. The tail vein blood glucose>16.7mmol/L after72hs was consided to be diabetic rat and taken into the experiment. All of the diabetic rats was feed with high-fat diet for another4weeks, after that they were randomly divided into two groups, the group of a-lipoic acid (LA, a-lipoic acid120mg/kg.d, n=15), and the diabetic control group (DC, Sodium Chloride2ml/d,n=15). During the experiment, animals eat and drink ad libitum, Body weight were measured once a week. After4weeks’drug intervention all the rats were anesthetized by pentobarbital sodium after overnight fasting for12hours, blood was taken from superior vena cava for the testing of blood lipids profile and glucose, skeletal muscle and hypohtalamus was taken immediately and put into the EP tubes and then frozened in the liquid nitrogen. After the experiment all the tissue was stored in-80℃refrigerator. Western blot method was used to detect the protein expression level of AMPKa and phosphorylated AMPK (Ph-AMPK), RT-PCR method was used to detect the mRNA level of AMPKa1/2, TRX, TXNIP, colorimetric assay was used to measure the level of MDA and T-AOC.Result:①The levels of glucose, triglyceride, cholesterol, low density lipoprotein in the DC group were significantly higher than those of NC group, however the level of high density lipoprotein is decreased obviously(P<0.05), a-lipoic acid intervention can decrese the levels of glucose, triglyceride, cholesterol, low density lipoprotein and increse the level of high density lipoprotein (P<0.05). The growth rate of DC were reduced compaired to NC(P<0.05), a-lipoic acid intervention also can reduce the growth rate of DC(P<0.05).②In the skeletal muscle and hypothalamus tissue of DC group, the expression of AMPKa, Ph-AMPKa were decreased compared with NC group(P<0.05), a-lipoic acid intervention can enhance the expression of AMPKa and Ph-AMPKa in the skeletal muscle, while in the hypothalamus were decresed(P<0.05).③Compaired to NC group, the level of AMPKa2mRNA in skeletal muscle and hypothalamus were dcreased in DC groups (P<0.05); compaired to DC, the level of AMPKa2mRNA in the skeletal muscle of the a-lipoic acid intervention group were increased (P<0.05) while in the hypothalamus were decreased (P<0.05); compaired to NC, the TRX-1mRNA、TXNIPmRNA in hypothalamus of DC and a-lipoic acid intervention group were increased (P<0.05); compaired to DC, the mRNA level of TRX and TXNIP in the hypothalamus of a-lipoic acid intervention group were increased (P<0.05).④In the hypothalamus of DC group, the level of MDA were incresed compared with the NC group(P<0.05), and the T-AOC were dereased(P<0.05); a-lipoic acid intervention can decrease the level of MDA compared to DC group(P<0.05), and increase the level of T-AOC in hypothalamus(P<0.05).Conclusion:1. a-lipoic acid have different effect on AMPK in skeletal muscle and hypothalamus, it can increase the activity of AMPKa in skeletal muscle while decrease in hypothalamus.2. a-lipoic acid show an protective effect of improving the metabolic disturbance of glucose and lipid and improving the oxidative stress in diabetes, which was achieved partly by activate the AMPK. |
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