Effect of Vitamin E on the Expression of SIRT1 and PGC-1α in Mice with Nonalcoholic Fatty Liver Disease / 中国药学杂志

OBJECTIVE: To investigate the effect of vitamin E (Vit E) on the expression of SIRT1 and PGC-1α in mice with nonalcoholic fatty liver disease(NAFLD), and to explore its role in the resistance against the oxidative stress. METHODS: As animal models of NAFLD, Male C57BL/6 mice were fed with high-fat diets for 24 weeks, the model mice was administered Vit E (50 mg·kg-1·d-1) intragastrically for 18 weeks from 7th week of modeling.The pathological changes in liver were determined by HE and Masson staining. The serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) analyzed using automatic biochemical instrumentation. The levels of liver superoxide-dismutase (SOD) and MnSOD were tested by xanthine oxidase assay. Total content of malondialdehyde (MDA) in liver homogenate was tested by thiobarbituric acid (TBA) method. The mRNA and protein levels of silent mating type information regulation 2 homolog 1(SIRT1) and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) were tested by Real-time PCR and immunohistochemistry assay respectively. RESULTS: Long-term high-fat diet induced NAFLD with the progression from liver steatosis, inflammatory response to fibrosis. The levels of serum ALT and AST in the rats of the NAFLD group were significantly higher than those of the normal group(P<0.05). The transcript and protein levels of liver SIRT1 and PGC-1α were significantly decreased compared with the normal group. The total contents of liver SOD and MnSOD were much lower than those of the normal group, while the MDA level increased significantly(P<0.05).The administration of Vit E to some extent reduced inflammation and fibrosis.After Vit E treatment, the levels of serum ALT and AST were significantly lower than those of the model group(P<0.01, P<0.05). The mRNA and protein levels of liver SIRT1 and PGC-1α became higher than those of the model group(P<0.05).Then liver SOD and MnSOD levels were significantly increased compared with the model group(P<0.05) while MDA content was reduced(P<0.05). CONCLUSION: Vitamin E corrects the imbalances of the oxidative and antioxidative system in mice models of high-fat diet-induced NAFLD by regulating the expression levels of the key factors of the SIRT1/PGC-1α signaling pathway, which reduces inflammation damage in liver and prevents the progression of NAFLD.

Regulation of pure total flavonoids from Citrus on TH17/Treg balance in mice with NASH / 中国中药杂志

This study aimed to investigate the involved immunologic mechanism of pure total flavonoids from Citrus (PTFC) on the development of non-alcoholic steatohepatitis (NASH). C57BL/6 mice were fed with high .fat diet for 16 weeks to induce the NASH model, and from the 7th week three dosages (25, 50 and 100 mg x kg(-1) x d(-1)) of PTFC were administrated intragastric for 10 weeks respectively. Serum TG, CHOL, ALT, AST were determined by biochemical assay, histopathological changes of the liver tissue were observed by HE staining, expression of RORyt and Foxp3 mRNA of the liver tissue was detected by Real-time PCR, and serum IL-17, IL-6, IL-10 and IL-4 were determined by.Cytometric Beads Array. As a result, we find that after the administration of PTFC, the in- flammation of the liver tissue of NASH mice was attenuated, liver function was improved, and the expression of RORgammat mRNA was higher in the liver tissue while which was lower of Foxp3 mRNA, the level of proinflammatory cytokines IL-17 and IL-6 decreased and the level of suppressive cytokines IL-10 and IL-4 increased. These data show that PTFC protects the development of NASH through regulating the Th17/Treg balance and attenuating inflammation.

Effect of pure total flavonoids from citrus on hepatic SIRT1/PGC-1alpha pathway in mice with NASH / 中国中药杂志

<p><b>OBJECTIVE</b>To observe the effect of pure total flavonoids from Citrus (PTFC) on the hepatic fatty degeneration, inflammation, oxidative stress and SIRT1/PGC-1alpha expressions in mice with non-alcohol steatohepatitis (NASH), and discuss the action mechanism of PTFC on NASH.</p><p><b>METHOD</b>Mice were given high-fat diet for 16 weeks to induce the NASH model. Since the seventh week after the model establishment, the mice were intervened with 100, 50 and 25 mg x kg(-1) x d(-1) PTFC for 10 weeks. The pathologic changes in hepatic tissues were observed with HE staining. The contents of TG, CHOL in hepatic tissue, as well as the levels of AST, ALT in serum were detected by using the biochemical process. The expression of SIRT1, PGC-1alpha and MnSOD mRNA in hepatic tissues were detected with Real-time PCR assay. SIRT1, PGC-1alpha protein and 8-OHdG expressions were determined with the immunohistochemical method. The SOD level in hepatic tissues was tested by the xanthine oxidase method. The MDA content in hepatic tissues was examined by the thiobarbituric acid method.</p><p><b>RESULT</b>The contents of TG, CHOL, NAFLD activity scores and ALT level in serum in hepatic tissues of mice in the model induced by fat-rich diet were obviously higher than that of the normal group (P < 0.010. The SIRT1, PGC-1alpha, MnSOD mRNA and protein expression in hepatic tissues were significantly lower than that of the normal group (P < 0.01). The expression of 8-OHdG and the content of MDA in hepatic tissues were obviously higher than that of the normal group (P < 0.01). After the intervention with different doses of PTFC, the NAFLD activity scores, the content of TG and the level of AST in serum were notably lower than that of the normal group (P < 0.01, P < 0.05); whereas the SIRT1, PGC-1alpha, MnSOD mRNA and protein expression were obviously higher than that of the normal group (P < 0.01, P < 0.05), with the significant decrease in the expression of 8-OHdG and the content of MDA (P < 0.01).</p><p><b>CONCLUSION</b>Oxidative stress/lipid peroxidation enhancement in in NASH mice induced by high-fat diet may be related to the changes in SIRT1/PGC-1alpha signal transduction pathway. PTFC could enhance the anti-oxidant capacity in liver, relieve the damage of reactive oxygen during the fatty acid metabolic process, and prevent NASH from the occurrence and development by regulating the SIRT1/PGC-1alpha signal pathway.</p>

Effect of Nrf2 and related factors on the progression of nonalcoholic steatohepatitis / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To explore the role of NF-E2-related factor 2(Nrf2) and its related factors in the progression of nonalcoholi steatohepatitis (NASH) by investigating the alterations of lipid metabolism and liver histopathology as well as the changes of mRNA and protein expression levels of Nrf2 and its related factors in rats during NASH progression.</p><p><b>METHODS</b>Male SD rats were randomly divided into normal group and model group, which were administrated with high fat diet to establish nonalcoholic steatohepatitis model. The rats from both groups were randomly killed at the end of 4, 12 weeks respectively. The levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) were detected in the serum and liver tissue; Changes in fat deposition in liver tissue were determined by oil red O staining. HE staining were used to observe the pathological changes of liver tissue and to calculate nonalcoholic fatty liver disease (NAFLD) activity score (hepatic steatosis, inflammation and ballooning degeneration of liver cells). The expression of Nrf2 in liver was detected by immunohistochemical staining. The mRNA and protein levels of Nrf2 and related factors in liver were determined by Realtime PCR and Western blot, respectively.</p><p><b>RESULTS</b>After 4 weeks of high fat diet, the levels of ALT, AST, TC in rat serum and TC, TG, LDL-C in liver were significantly increased compared with that of the normal group (P < 0.01, P < 0.05). After 4 weeks of high fat diet, the levels of ALT, AST, TC, TG in serum and TC, TG, LDL- C in liver increased further (P < 0.01, P < 0.05). Until the 12th week, the content of HDL-C in liver was significantly lower than that of the normal group (P < 0.05). At the end of the 4th or the 12th week, lipid droplets in the model rat liver cells were heavily dyed red and hepatic steatosis increased severely, with ballooning degeneration of liver cells. With the extension of high fat diet feeding time, fat deposition in the liver tissue, hepatic steatosis, NAFLD score, Nrl2 expression were significantly increased (P < 0.01). Expression levels of mRNA and protein of Nrf2, heme oxyenase 1(HO1), NADPH quinone oxidoreductase 1(NQO1), γ-glutamylcysteine synthethase (γ-GCS), glutathione S-transferase (GST) in the model rats increased or decreased at the end of the 4th or the 12th week differentially, (P < 0.01, P < 0.05) with the more significant changes at the end of the 4th week than the 12th week.</p><p><b>CONCLUSION</b>Nrf2 and its related factors may be involved in the occurrence and development of nonalcoholic fatty liver disease, which may play an important role in the process of NASH formation.</p>