| Objective: To investigate the effects of the taurine on the formation of hepatic injury in type 2 diabetic rats and explore its possible mechanism.Methods:The study was performed after all rats were allowed to acclimate for 1week. 80 Sprague Dawley(SD) rats were randomly divided into control group and type 2 diabetes mellitus group.The control group was given ordinary feed and the latter was fed with high-fat and high-sucrose diet for four weeks,the mode of type 2diabetes mellitus was made by intraperitoneal injection with low-dose streptozotocin(STZ) continuously. Then,the latter group was divided into diabetic model group, low-dose of taurine(200mg·kg-1)and high-dose group of taurine(400mg·kg-1). Moreover,the medication administration group was given the high-fat diet and treated by oral medication of taurine for 8 weeks.After the last treatment of taurine and an overnight fast,water freely,the fasting blood glucose of all rats were detected.Then under 10% chloral hydrate anesthesia,the body weight of sample and the liver weight were determined,and the liver index should be calculated.The levels of the serum markers for liver fibrosis and liver function were measured.The livers were removed to make HE and Masson staining,immunohistochemistry and fluorescence quantitative-real time PCR in order to evaluate the effect of taurine on the hepatic fibrosis.HE and Masson staining were made to observe the degree of liver fibrosis; Immunohistochemical and fluorescence quantitative PCR were employed to detect transforming growth factor beta1(TGF-β1)of liver tissue of rat;Fluorescence quantitative PCR was used to detect the expression of the mi RNA-200 b and mi RNA-29 b.Results :(1)Comparing with the control group,the rats in model group were not active with coarse hair.The food-intake,drinking, excreting waste and urine output increased in model group,and the body weight decreased with increasing mortality.Compared to the model group,the food-intake,drinking,excreting waste and urine output were improved in the administration group with lower mortality rate.(2)After the rats with type 2 diabete mellitus have been fed with high fat diet for 8weeks,their fasting blood glucose and hepatic coefficient increased significantly, and the body weight decreased significantly in model group compared with control group(P<0.05).There is a slightly change that the blood glucose and hepatic coefficient decreased,and the body weight decreased in treatment group compared with model group.There was statistically significant difference of body weight,and there was no obvious influence on the liver coefficient of rats in taurine group.(3)The levels of the serum markers(TC, TG, AST, HA, LN)for liver fibrosis and liver function increased significantly in model group compared with control group.There is a remarkable change that the TC, TG and AST decreased, HA and LN were decreased significantly(P<0.05),and the expression of PCIII decreased in treatment group compared with model group.(4)The result of HE staining showed that hepatic cells were well-arranged and distributed neatly and orderly,double membrane structure was clear without obvious fat vacuoles and fiber in control group.In the model group,the structure of liver lobule was abnormal and a lot of collagen fibers located in portal area and central vein.The liver cells of portal area and interstitial cells increased in rats of the model group with Collagen fiber hyperplasing and fiber interval aroud the heptic cells forming as well as obvious fibrosis,which were aggravated with the time prolonging.The structure of rat’s liver lobule and liver structure were obvious in the therapy group with taurine,the less fat vacuoles were found in hepatic cells.The liver fibrosis has been improved with taurine treatment,and the extent of fibrosis in high dose group is lighter than low dose group.The liver fibrosis model with type 2 diabetes mellitus is successful,taurine treatment can obviously alleviate liver fibrosis.(5)After Masson staining,red liver cells have different amount of fiber in blue.There is not obvious fibrosis,liver cell arranged neatly.The collagen fiber of heptic tissue increased significantly,came into being fiber interval segregating liver cells,making cells in a disordered arrangement.And we can see that liver fibrosis were significantly increased.Hepatic fibrosis appeared,fiber cells actively proliferated and the deposit of collagen gradually increased in rat liver.The partial liver tissue became blue after masson staining,fibrosis.However, the blue area and hepatic fibrosis decreases while rats were treated with taurine,and the extent of fibrosis in high dose group is lighter than low dose group(P<0.05).Taurine can significantly reduce liver fibrosis of type 2diabetes mellitus.(6)Immunohistochemical staining was used to detect the expression of TGF-β1 of liver tissue each group.The positive material was claybank mainly localized in the cytoplasm,barely in the nuclei of liver cell,and the nuclear was pale blue.In the control group, the structure of liver lobule was normal and a few of blue located in portal area and central vein,and with shallow coloring. Under the optical microscope,the cells exhibited claybank in the cytoplasm and with pale blue staining in the nucleolus,thus the TGF-β1 localized in the cytoplasm were identified in model group.The expression of TGF-β1 increased obviously and stained stronger.In comparison with model group,the expression of TGF-β1 decreased markedly in administered group after taurine treatment(P<0.05).The results suggested that taurine can reduce the expression of TGF-β1 and improve liver fibrosis of the liver tissue of type 2 diabete mellitus.(7)The expression of TGF-β1 m RNA increased significantly compared with control group(P<0.05),and it decreased significantly in taurine group in comparation with model group(P<0.05).(8)The fluorescent quantitative PCR was used to detected the expression of mi RNA-200 b and mi RNA-29 b of liver tissue in each groups,including control group,model group,low-does group and the high-does group.Compared with normal group,the level of mi RNA-200 b and mi RNA-29 b in the liver of model group downregulated significantly(P<0.05).The expression of mi RNA-200 b and mi RNA-29 b in taurine group showed an increasing tendency,which increased significantly in high-dose group compared with model group(P<0.05).Conelusions:(1)Taurine can alleviated liver damage,induced by high glucose and fat diet combined with intraperitoneally injection of STZ in rats of type 2 diabete mellitus,and improved hepatic fibrosis.(2)The expression of TGF-β1 m RNA and its protein were decreased in liver in diabetic rats induced by high fat diet combined with intraperitoneally injection of STZ.This may be the mechanism of taurine protecting liver tissue from liver fibrosis.(3)Taurine can upregulate the level of mi RNA-200 b and mi RNA-29 b in the rats liver with type 2 diabete mellitus,making its expression returning to normalization.And mi RNA-200 b and mi RNA-29 b downregulates the expression of TGF-β1.Taurine can protect liver tissue by regulating the content of mi RNA-200 b and mi RNA-29 b decreasing transforming growth factor beta-1. |
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