| Objective: With the improvement of living standards and increase of the bad living habits,type 2 diabetes mellitus has become one of the common disease in clinical.T2 DM is rising year by year and trend to younger,greatly influence the people healthy,increase the social burden,its chronic complicat-ions can be widely involved in heart,liver,kidney,eye,blood vessels,nervous system and so on.The incidence of diabetic liver disease is rising year by year.Fatty liver is the most common reason and the pathogenesis has not yet been systematically c larified,it is thought to be closely related to oxidative stress,inflammatory reaction.The metabolic disorder of sugar and lipid,insulin resistance,glycosylation end-products and so on.In recent years,oxidative stress and insulin res istance have attracted the attention of the people.Mammalian target of rapamyein is a hub connecting multiple s ignaling pathways,oxidative stress can induce excessive activation of mTOR pathways which caused by hyperglycemia and hyperlipidemia has been proved.The excessive activation of mTOR can affect the insulin s ignaling pathway,aggravating glucolipid metabolic disorder and promote the occurrence of diabetic liver disease.MTOR signalling pathway play a important role in regulation the insulin signaling pathway which can become the treatment targets of diabetic liver disease.Lipoic acid is the strongest antioxidant in natural which is not only can remove the body of a variety of reactive oxygen free radicals,but can restore the body’s antioxidant system,strengthen the antioxidant ability.Lipoic acid has a broad application prospect in the treatment of diabetic liver disease.This experiment through preparation of T2 DM rats model,lipoic acid intervention and than detection the phosphoryla-tied mTOR and AMPK which the markers of mTOR signaling pathwayin every group of liver to investigate whether Alpha-lipoic acid can resistance oxidative stress and at the same time inhibition mTOR signaling pathways activated to protection the liver of diabetic rats.Methods: Twenty-eight male Sprague-Dawley(SD)rats aged 6 weeks and weighing 180 g ± 20 g.The rats in the clean laboratory environment were fed for 1 week.The rats were randomly divided into three groups: the control group(n = 6),the diabetic group(n = 8)and the lipoic acid group(n = 8).The control group was fed with normal diet,and the diabetic group and the lipoic acid group were fed with high glucose and high fat diet.Group B and Group C were fed with streptozotocin 30 mg / kg after one week of high glucose and high fat diet for 4 weeks.At the end of the 6th week,the fasting blood glucose(FBG)of rats in group B and group C was greater than or equal to 7.8 mmol / L as model of type 2 diabetes mellitus.The rats in Alpha-lipoic acid group were given Alpha-lipoic acid at a dosage of 100 mg/kg by daily intraperitoneal injection and the ones in control group and diabetic group were received the equal volume normal saline,the intraperitoneal injection was continued for 8 weeks.At the end of the 14 week:1.took blood from abdominal aorta,and FBG,FINS,alanine aminotransferase(ALT),aspartate aminotransfer-ase(AST),alka linephosphatase(ALP),gamma-glutamyl transpeptidase(γ-GGT),triglyceride(TG),total cholesterol(TC),low dens ity lipoprotein cholesterol(LDL-C),high dens ity lipoprotein cholesterol(HDL-C)were measured use a part of the biood.Another part of blood take clear liquid after centrifugal,freeze on-80℃ refrigerator for testing 8-OHdG.2.Take part of the liver fixed in 4% paraformaldehyde,for HE staining to observe the liver morphology and immunohistochemical staining detection the protein expression of mTOR signaling pathway,The data was dealt with SPSS21.Results:1.Comparison of liver mass coefficient in each groupCompared with the normal control group,the liver weight index of the diabetic group and lipoic acid were significantly higher than that of normal control group(P<0.05);The liver weight index of lipoic acid group was significantly lower than that of diabetes mellitus group(P<0.05).2.Comparison of HOMA-IR in each groupCompared with the normal control group,the HOMA-IR of diabetic group and the lipoic acid group was significantly higher than that of normal control group(P <0.05);The HOMA-IR of lipoic acid group was significant-ly lower than that of the diabetes mellitus group(P <0.05).3.Comparison of biochemical indexes in each groupCompared with normal control group,ALT,AST,γ-GGT,TG,TC and LDL-C were significantly increased in the diabetic group and lipoic acid group(P <0.05);The HDL-C in the diabetic group and lipoic acid group was lower than that of normal control group(P <0.05);The ALT,AST,γ-GGT,TG,TC and LDL-C of lipoic acid group were significantly lower than that of diabetes mellitus group,the difference was statistically significant(P <0.05);The HDL-C of lipoic acid group was higher than that of diabetes mellitus group(P <0.05).4.Comparison of 8-OhdG level in each groupCompared with the normal control group,the level of 8-OHdG in diabetic group and the lipoic ac id group was significantly higher than that in normal control group(P <0.05);The level of 8-OHdG in lipoic acid group was significantly lower than that of diabetes mellitus group(P <0.05).5.Liver HE stainingUnder the light microscope,HE staining showed that the normal liver tissue morphology was liver lobule structure integrity,liver cell arrange ment rules,no steatosis and necrosis,no inflammatory cell infiltration;The part of liver cells had steatosis in diabetes group,lipid droplets was large bubblebased,accompanied by more inflammatory cell infiltration and punctate necro-sis,but also to see perivascular inflammation and portal area a small amount of fibrous tissue hyperplasia.Lipoic acid group of steatosis significantly reduced liver cells,occasionally small intracellular cytoplasmic vacuoles and inflammatory foci.6.Liver electron microscopyElectron microscopy showed: liver nuc leus of normal group was round or round like,nuclear membrane smooth,nucleolus obvious,centered,nuclear space without expans ion,nuclear chromatin distribution evenly.Mitochondri-al shape normal,rough endoplasmic reticulum distribution.Cytoplasm almost invis ible or have a very small amount of lipid droplets;diabetes group: the nucleus of the nuclear membrane irregular,nucleolus side set,nuclear space expansion,uneven.Mitochondria hyperplas ia,swelling,ridge fusion.Rough endoplasmic reticulum significantly expanded.Cytoplasm can be seen within the size of fat droplet deposition;lipoic acid group: the shape of liver cells most of the rules,nuclear clearance is normal.Hepatocyte steatosis was significantly less than in diabetic group,cytoplasmic lipid droplets decreased,mitochondrial swelling was not obvious,mitochondrial ridge showed clear,rough endoplasmic reticulum and smooth endoplasmic reticulum structure was normal.7.Liver phosphorylated mTOR,AMPK protein expression levelThe expression level of phosphorylated mTOR in diabetic group was significantly higher than that in normal group and lipoic acid group(P <0.05);The level of phosphorylated mTOR in lipoic acid group was significantly lower than that in diabetes mellitus group,the difference was statistically significant(P <0.05);The level of phosphorylated AMPK in diabetic group was significantly lower than that in normal group and lipoic acid group(P <0.05);The level of phosphorylated AMPK in lipoic acid group was significantly higher than that in diabetes mellitus group,the difference was statistically significant(P <0.05).Conclusions:1 Diabetic rats increased blood transaminase,microscopic observation of liver histological changes,indicating that there are liver injury in diabetic rats.Lipid acid intervention group significantly improved liver function,liver histology was significantly improved,indicating that lipoic acid has a protective effect of the liver.2 Diabetic group 8-OHdG levels were significantly increased,indicating that there is oxidative stress in diabetic rats.The level of 8-OHdG in the lipoic acid group was significantly decreased,indicating that lipoic ac id had antioxidant stress.3 Phospholipid mTOR protein expression level was significantly reduced,phosphorylated AMPK protein expression level was significantly increased,indicating that lipoic acid may by inhibiting the abnormal activation of mTOR path-way to play the role of liver protection in diabetic rats. |
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