Role of SIRT1/AMPK pathway in early intervention of Lira alleviating non-alcoholic fatty liver disease caused by high-fat diet in rats

AIM To investigate the effect of early intervention of glucagon-like peptide-1 (GLP-1) receptor agonist liraglutide (Lira) on oxidative stress, glucose tolerance, hepatic steatosis and insulin resistance of the rats with high-fat diet (HFD)-induced non-alcoholic fatty liver disease (NAFLD), and to explore the role of silent information regulator 1 (SIRT1)/AMP-activated protein kinase (AMPK) signaling pathway in this process. METHODS Twenty-four male SD rats were randomly divided into normal diet (ND) group, HFD group and HFD+Lira group, with 8 rats in each group. After 1 week of adaptive feeding, the rats in HFD+Lira group were subcutaneously injected with Lira (200 μg/kg) per day at a fixed time point, while the rats in the remaining 2 groups were injected with normal saline at the same volume. During the intervention, the body weight, hair, appetite, defecation and activity of the rats were observed to adjust the dosage timely. The body weight, food intake and blood glucose were recorded weekly. Glucose tolerance test was performed at the end of the 16th week. At the end of the 18th week, hyperinsulinemic euglycemic clamp test was conducted after anesthesia. Blood was taken from the carotid artery. The liver and adipose tissues from different parts were taken after death. The serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and other indicators were detected. HE staining was used to observe the pathological changes of the liver tissue. Lipid accumulation in the liver tissues was observed by oil red O staining. Liver fibrosis was observed by Masson staining and Sirius red staining. Fluorescence staining for reactive oxygen species (ROS) was used to observe the oxidative stress in the liver. The expression of GLP-1 receptor in the liver was observed by immunofluorescence staining. The expression and localization of SIRT1 and phosphorylated AMPK at Thr172 [p-AMPK (Thr172)] were observed by immunohistochemical staining. The protein levels of AMPK, p-AMPK (Thr172), SIRT1, phosphorylated sterol regulatory element binding protein-1c at Ser372 [p-SREBP-1c (Ser372)], phosphorylated acetyl coenzyme A carboxylase at Ser79 [p-ACC (Ser79)], carnitine palmitoyltransferase 1A (CPT1A) and fatty acid synthase (FAS) in liver tissues were determined by Western blot. RESULTS The results of HE and oil red O staining of rat liver tissues in HFD group confirmed the structural disorder and serious lipid accumulation, while Masson and Sirius red staining showed severe fibrosis, suggesting the successful establishment of NAFLD rat model. Compared with ND group, the levels of total cholesterol (TC), triglyceride (TG), AST and ALT in serum, and the levels of malondialdehyde (MDA), TC, TG and ROS in liver tissues in HFD group were significantly increased (P<0.01), while the activity of superoxide dismutase (SOD) was decreased (P<0.01). The protein levels of p-AMPK (Thr172), SIRT1, p-SREBP-1c (Ser372), p-ACC (Ser79) and CPT1A in the liver tissues were significantly reduced (P<0.05 or P<0.01), while the expression of FAS was increased （P<0.01）. Compared with HFD group, lipid accumulation and fibrosis in the liver tissues of the rats in HFD+Lira group were significantly attenuated, the serum levels of TC, TG, AST and ALT, and MDA, TC, TG and ROS in liver tissues were markedly reduced (P<0.05 or P<0.01), while SOD activity was increased (P<0.05). The protein levels of p-AMPK (Thr172), SIRT1, p-SREBP-1c (Ser372), p-ACC (Ser79) and CPT1A in the liver tissues were significantly increased (P<0.05 or P<0.01), while the expression of FAS was decreased （P<0.01）. CONCLUSION Lira attenuates insulin resistance, oxidative stress and fibrosis, and improves liver lipid metabolism in the rats with NAFLD induced by HFD, which may be mediated by SIRT1/AMPK signaling pathway.     

Influence of Tangshenfang on diabetic liver injury and the expression of SIRT1 and PGC-1α in the liver tissue

AIM: To observe the effect of Tangshenfang (TS) on the liver protection and the levels of silent information regulator 1 (SIRT1) and peroxisom proliferator-activated receptor γ coactivator-1α (PGC-1α) in the liver tissue. METHODS: The rat model of diabetes mellitus (DM) was established by intravenous injection of streptozotocin (STZ;30 mg/kg) after having the high fat/high glucose diets for 1 month. The diabetic rats were randomly divided into DM group, DM with high-dose TS (TS^Hi) group, medium-dose TS (TS^Med) group and low-dose TS (TS^Low)group. The normal rats were served as control group. There were 8 rats in each group. After treatment with TS for 12 weeks, the serum biochemical indices including fasting blood glucose (FBG), triglyceride (TG), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were tested. Fasting insulin (FINS) was also detected by radioimmunoassay, and homeostatic model assessment for insulin resistance (HOMA-IR) was calculated. The serum levels of tumor necrosis factor-α (TNF-α) and interleukin-1 (IL-1) were measured by ELISA. The activity of SOD and content of MDA in the liver tissues were measured by the methods of hydroxylamine and thiobarbituric acid. The liver pathological changes were observed under light microscope with HE and Masson staining. The protein expression of SIRT1and PGC-1α in the liver tissues was determined by Western blot. RESULTS: In DM group, serum FBG, TG, ALT, AST, FINS, HOMA-IR, TNF-α and IL-1 were obviously increased compared with the control group (P<0.01). The fatty changes, local necrosis, inflammation and fibrosis in the liver tissues were observed. The content of MDA in liver increased, while the activity of SOD decreased markedly. The protein expression of SIRT1 and PGC-1α was decreased (P<0.05). In TS treatment groups, all these changes in DM rats were markedly reversed by TS, and the protein expression of SIRT1 and PGC-1α in the liver tissues was markedly increased. CONCLUSION: TS may protect the rats from diabetic liver injury by increasing the expression of SIRT1 and PGC-1α, and thereby improving insulin resistance and oxidative stress.     

Effects of liraglutide on adiponectin and insulin resistance in rats with non-alcoholic fatty liver disease

AIM：To investigate the effects of glucagon-like peptide 1 analog, liraglutide, on adiponectin and insulin resistance in the rats with diet-induced non-alcoholic fatty liver disease (NAFLD). METHODS：Male rats were randomly divided into 3 groups:normal diet (ND) group (n=10), high-fat diet (HFD) group (n=10), and HFD with intraperitoneal injection of liraglutide group (n=10, first 12 weeks with HFD, later 4 weeks with liraglutide). All treatments continued for 16 weeks, and then the rats were killed ethically and the blood samples and liver tissues were collected. The levels of alanine aminotransferase (ALT), fasting blood glucose (FBG), total cholesterol (TC) and triglyceride (TG) were detected by a biochemical automatic analyzer. The levels of free fatty acids (FFAs), fasting insulin (FINS) and adiponectin were measured by RIA and ELISA. RESULTS：Compared with HFD group, the body weight, liver index, homeostasis assessment-insulin resistance (HOMA-IR), the serum levels of TG, TC, ALT and FBG, and the liver levels of TG, TC and FFAs in the rats in liraglutide group were apparently lower, the degree of hepatic steatosis and inflammatory activity significantly decreased (P<0.05), and the level of adiponectin in the serum and liver homogenate increased ob-viously (P<0.05). The level of adiponectin in the liver homogenate was negatively correlated with the levels of FFAs in the liver homogenate. CONCLUSION:Liraglutide is beneficial for NAFLD rats to improve insulin resistance and reduce hepatic steatosis by increasing the level of adiponectin in the serum and liver tissues.     

Activation of PPARs is involved in effect of bezafibrate on diabetic hepatopathy in mice

AIM: To investigate the effects of bezafibrate (BEZ) on diabetic hepatopathy in mice. METHODS: Diabetic hepatopathy model was established by a long-high-energy diet combined with streptozotocin (40 mg·kg^-1·d^-1× 5 d, ip), and then bezafibrate (75 mg·kg^-1·d^-1, ig) was supplemented for 4 weeks. Fasting blood glucose (FBG) was detected every week. The structure of liver was observed by HE staining, and the liver function was measured by observing the levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Total cholesterol (TC), triglyceride (TG), insulin and HbA1c were determined by commercial kits, and then HOMA insulin resistance index (HOMA-IR) was calculated. The expression of peroxisome proliferator-activated receports (PPARs) at mRNA and protein levels was determined by RT-qPCR and Western blot, respectively. RESULTS: After 7 days of treatment with streptozotocin, the FBG level of the mice exceeded 11.1 mmol/L. At the end of the experiment, the structural deformation of the hepatocytes (containing abundant fat vacuoles, infiltrated by inflammatory cells, etc.) was observed, with the increases in insulin, HbA1c, HOMA-IR, TC, TG, ALT and AST in diabetic mice (P<0.01). Meanwhile, the expression of PPARα, PPARβ and PPARγ at mRNA and protein levels was decreased (P<0.01). Bezafibrate treatment markedly attenuated the structural and functional damages of the liver in the diabetic mice (P<0.01), and reduced the levels of FBG, insulin, HbA1c, HOMA-IR, TC and TG (P<0.05). Bezafibrate also up-regulated the expression of PPARα, PPARβ and PPARγ (P<0.01). CONCLUSION: Bezafibrate attenuates hepatic injury in diabetic mice via the activation of PPARs-related signaling pathway.     

Vaspin and insulin signaling pathways in obstructive sleep apnea-hypopnea syndrome animal model

AIM: To establish a suitable chronic intermittent hypoxia (CIH) model in rats for modeling the obstructive sleep apnea-hypopnea syndrome (OSAHS) and further to explore the relationship between vaspin and insulin signaling pathways at mRNA and protein levels. METHODS: Healthy male Wistar rats were divided into control group and CIH group. The rats in control group were raised under physiological condition, and the rats in CIH group were kept in the plexiglass chamber between 9:00~17:00 and underwent intermittent hypoxic challenge 8 h/d for 8 weeks. The blood pressure of arteria caudilis in the rats was measured by tail cannulation before and after study. Fasting plasma glucose (FPG), total cholesterol (TC), triglycerides (TG), fasting insulin (FINS), vaspin and adiponectin levels were measured. The mRNA expression of vaspin was detected by real-time PCR. The protein levels of vaspin, Akt and p-Akt were determined by Western blotting.RESULTS: Before the experiment, the weight and blood pressure of the rats had no significant difference, while after the experiment the blood pressure in CIH group was obviously higher than that in control group. FPG, FINS, TG and TC in CIH group were also markedly higher than those in control group (P<0.05). Serum vaspin concentration was significantly correlated with FPG, FINS, HOMA-IR and TC. The expression of vaspin at mRNA and protein levels in the fat tissue of CIH group was evidently higher than that in control group. The protein levels of p-Akt decreased distinctly in CIH group. CONCLUSION: The levels of FINS, HOMA-IR, SaO2 and vaspin were markedly higher than those in control group, indicating that there was a close relationship between vaspin and insulin resistance in OSAHS.     

Effect of ginsenoside Rb1 on liver cell pyroptosis in hyperlipidemia rats and its possible mechanism

AIM:To discuss the mechanism of ginsenoside Rb1 against liver lipid deposition by observing the effect of ginsenoside Rb1 on liver cell pyroptosis in hyperlipidemia rats. METHODS:Totally 32 healthy SPF rats were randomly divided into control group, model group, ginsenoside Rb1 group and simvastatin group. The rats in control group was given the basic feed, while the others were given high-fat diet. The rats in ginsenoside Rb1 group and simvastatin group were given corresponding drugs. The rats in control group and model group were intraperitoneal injected with equal volume of saline. Eight weeks later, the serum levels of triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) were tested by the automatic biochemistry analyzer. The pathological changes of the liver tissues were observed with HE staining. The protein and mRNA expression levels of pyroptosis-related factors NLRP3, caspase-1, IL-1β, IL-18 and GSDMD were detected by Western blot and RT-qPCR. RESULTS:Compared with control group, the serum levels of TC, TG and LDL-C in model group were increased significantly (P<0.01), and the HDL-C content was decreased significantly (P<0.05). The steatotic liver cells covered the visual field. The mRNA and protein expression levels of NLRP3, caspase-1, IL-1β, IL-18 and GSDMD were increased significantly (P<0.01). Ginsenoside Rb1 significantly decreased the serum levels of TC, TG and LDL-C (P<0.05), and significantly increased the content of HDL-C (P<0.01). Ginsenoside Rb1 also significantly decreased the degree of steatosis, and the number and size of lipid droplets. The mRNA and protein expression levels of NLRP3, caspase-1, IL-1β, IL-18 and GSDMD were decreased significantly (P<0.05 or P<0.01). CONCLUSION:Ginsenoside Rb1 atte-nuates liver injury and inhibits liver lipid deposition in hyperlipidemia rats by reducing the expression of hepatic pyroptosis-related factors.     

Inhibitory effect of salidroside on liver oxidative stress in rats with non-alcoholic steatohepatitis

AIM：To explore the effects of salidroside (SDS) on the oxidative stress in liver tissues from rats with non-alcoholic steatohepatitis (NASH). METHODS：The experimental animal model of NASH was established in SD rats fed on high-fat and high-cholesterol diet (HFHCD) for 14 weeks. SDS (300 mg·kg-1·d-1) was administered via gavage daily from the 8th week after HFHCD feeding. At the end of the 14th week, serum samples were taken for detection of alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride (TG) and total cholesterol (TC). Liver tissues were taken for TG, TC, malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH) detection. The content of 8-isoprostaglandin F2α (8-iso-PGF2α) in liver tissues was determined by ELISA. The liver histopathological changes were observed under microscope with HE staining. The expression of 8-hydroxydeoxyguanosine (8-OHdG) in liver tissues was determined by immunohistochemical staining. RESULTS：At the end of the 14th week, ALT, AST, TG and TC in serum, and TG, TC, MDA and 8-iso-PGF2α in liver homogenate in NASH model group were significantly increased compared with control group, while SOD and GSH in liver tissues were significantly decreased. The liver expression of 8-OHdG in NASH model group was higher than that in control group. Compared with NASH model group, SDS significantly inhibited the elevation of serum ALT, AST, TG and TC, and liver TG, TC, MDA and 8-iso-PGF2α, but increased the levels of SOD and GSH in liver tissues. Meanwhile, the liver histopathological score and 8-OHdG expression were decreased in SDS treatment group. CONCLUSION：Salidroside can effectively inhibit steatohepatitis induced by HFHCD, and its antioxidant effect may be one of the mechanisms.     

PPARs signaling pathway is involved in diabetic hepatopathy in mice

AIM: To investigate the role of peroxisome proliferator-activated receptors (PPARs)-inflammation signaling pathways in diabetic hepatopathy. METHODS: Diabetic mouse model was established by feeding the mice with a high-energy diet for 4 weeks combined with intraperitoneal injection of streptozotocin (STZ; 40 mg·kg^-1·d^-1 for 5 d). The hepatopathy model was confirmed by histopathological observation and the indexes of liver function, such as alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP), after another 4 weeks. Moreover, fasting blood glucose (FBG), and serum levels of total cholesterol (TC), triglyceride (TG) and insulin were measured, and the HOMA insulin resistance index (HOMA-IR) was calculated. The mRNA and protein expression levels of PPARs and inflammation-related factors were measured by qPCR and Western blot, respectively. RESULTS: After treatment with STZ for 7 d, the FBG of mice exceeded 11.1 mmol/L, suggesting that the diabetic model was established. After 4 weeks, the structural deformation of the hepatocytes (including hepatocytes containing abundant fat vacuoles, and inflammatory cell infiltration), and the increases in the serum levels of insulin, HOMA-IR, TC, TG, ALT, AST and ALP were observed (P<0.01), indicating the occurrence and progression of hepatopathy in diabetic mice. Meanwhile, compared with the control group, the mRNA and protein expression of PPARα, PPARβ and PPARγ decreased, but the expression of nuclear factor-κB (NF-κB), cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) significantly increased in the diabetic hepatopathy mice (P<0.01). CONCLUSION: Down-regulation of PPARα, PPARβ and PPARγ and activation of NF-κB-COX-2/iNOS signaling pathways may be involved in the diabetic hepatopathy in mice induced by long-term high-energy diet feeding combined with intraperitoneal injection of STZ.     

Protective effect of curcumin analogue L6H4 on diaphragm of type 2 diabetic rats

AIM: To investigate the protective effect of curcumin analogue L6H4 on diaphragm of type 2 diabetic rats.METHODS: SPF male Sprague-Dawley rats (n=40) were randomly divided into 5 groups: normal control (NC) group, high fat (HF) group, high fat+L6H4 treatment (FT) group, diabetes mellitus (DM) group and DM+L6H4 treatment (DT) group. The rats in the later 4 groups were fed with high-fat diet. After 4 weeks of high-fat diet fee-ding, the rats in DM and DT groups were intraperitoneally injected with streptozotocin to induce type 2 diabetes melliutus. The rats in FT and DT groups were given L6H4 by gavage for 8 weeks. Blood glucose and blood lipid levels were detected biochemically. Fasting serum insulin (FINS) level was measured by radioimmunoassay and insulin resistance index (HOMA-IR) was calculated. Serum adiponectin (APN) level was measured by ELISA. The morphological changes of the diaphragm were observed under light and transmission electron microscopes. Lipid deposition and the activity of succinate dehydrogenase (SDH) and NADH-tetrazolium reductase (NADH-TR) were observed by enzyme histochemical staining. The content of malondialdehyde (MDA) and the activity of superoxide dismutase (SOD) in the diaphragm were measured by thiobarbituric acid method and hydroxylamine method, respectively. The protein expression of adiponectin receptor 1 (AdipoR1) in the diaphragm was determined by immunohistochemistry and Western blot. RESULTS: The levels of blood lipids, blood glucose, FINS and HOMA-IR in HF and DM groups were higher than those in NC group, but decreased after L6H4 treatment. The serum APN level in HF and DM groups was lower than that in NC group, but increased after treatment with L6H4. The muscle fibers of the diaphragm were shrunk, fat particles accumulated in the muscle fibers, and the mitochondria were slightly swollen in HF and DM groups. The diaphragmatic fibrosis was obvious in DM group. These lesions were relieved after L6H4 treatment. Compared with NC group, the level of MDA and the activity of SDH and NADH-TR in the diaphragm were increased in HF and DM groups, but decreased after treatment with L6H4. The activity of SOD and the expression of AdipoR1 in the diaphragm were lower than those in NC group, but increased after L6H4 treatment.CONCLUSION: The curcumin analogue L6H4 exerts a protective effect on diaphragm in type 2 diabetic rats. The strengthened protein expression of AdipoR1, the increased serum level of APN, and anti-lipid peroxidation may be involved in the process.     

mRNA expression of insulin receptor and leptin receptor in liver of nonalcoholic fatty liver disease from diabetic rats

AIM: To observe the pathologic changes of liver in diabetic rats and to investigate the role of mRNA expression of insulin receptor and leptin receptor in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). METHODS: Twenty male Sprague-Dawley rats were divided randomly into two groups: normal control group and diabetic group. After fed with high-fat diet for 4 weeks, diabetic rats were injected with streptozotocin at a dosage of 30 mg/kg intraperitoneally to induce NAFLD model of type 2 diabetes mellitus. Then the diabetic animals were fed with high-fat diet continuously for 12 weeks. At the end of the experiment, the rats were sacrificed, the concentrations of blood glucose, serum lipid, ALT and AST were measured biochemically. The levels of serum leptin and serum insulin were detected by enzyme-linked immunosorbent assay (ELISA) and radio immunoassay (RIA), respectively. The pathologic changes of liver were observed under light microscopy (LM) stained with HE, Sudan Ⅲ and Masson trichrome staining, respectively. The ultra-structural changes of liver were observed under transmission electron microscopy (TEM). Additionally, the mRNA expressions of PEPCK, G6Pase, insulin R and leptin R from rat livers were assayed by semi-quantitative RT-PCR. RESULTS: The levels of blood glucose, serum insulin, serum TG, ALT and AST increased significantly (P<0.01), serum TC elevated (P<0.05), and the levels of serum leptin decreased (P<0.01) in diabetic group compared to those in normal control group. Obvious liver fatty degeneration, piecemeal necrosis with accompanying inflammatory infiltration and fibrosis were found under LM. Hepatocytes pyknosis, lots of lipid deposits in cytoplasm of hepatocytes, proliferation of collagen in space of Disse were observed under TEM in diabetic group. The expression of insulin R and leptin R mRNA in liver from diabetic rats increased significantly (P<0.01) while the expression of PEPCK and G6Pase mRNA remained unchanged. CONCLUSION: Insulin resistance plays an important role in the pathogenesis of NAFLD. Low level of serum leptin, up-regulation of mRNA expression of insulin R and leptin R in liver caused by insulin resistance may be involved in this process.     

Serum levels of inflammatory factors and adiponectin in type 2 diabetic retinopathy patients

AIM: To investigate the serum levels of inflammatory factors and adiponectin in type 2 diabetic retinopathy (DR) patients.METHODS: One hundred and ten cases of type 2 diabetic patients were divided into 3 groups: no diabetic retinopathy group (DM, n=35), non-proliferative diabetic retinopathy group (NPDR, n=45), and proliferative diabetic retinopathy group (PDR, n=30). Other 40 normal persons served as controls (NC group). The physical examinated was performed for each patient. Serum levels of fasting plasma glucose (FPG), glycated hemoglobin A1c (HbA1c), 2 h postprandial plasma glucose (2hPG), fasting insulin (FINS), total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), adiponectin, intercellular adhesion molecule-1(ICAM-1), tumor necrosis factor-α (TNF-α) and high-sensitivity C-reactive protein (hs-CRP) were measured. Insulin resistance index (HOMA-IR) was also calculated.RESULTS: The systolic blood pressure, body-mass index, waist-hip ratio, serum levels of TG, LDL-C, FPG, 2hPG, HbA1c, ICAM-1, TNF-α, hs-CRP and HOMA-IR were significantly higher in DM group, NPDR group and PDR group than those in NC group (P<0.05). The systolic blood pressure, serum levels of ICAM-1, TNF-α, hs-CRP and HOMA-IR were higher in NPDR group and PDR group than those in DM group (P<0.05). The serum concentration of adiponectin was lower in DM group, NPDR group and PDR group than that in NC group (P<0.05), and that was also lower in NPDR group and PDR group than that in DM group (P<0.05). The negative correlations between adiponectin and ICAM-1 (r=-0.735,P<0.01), TNF-α (r=-0.781,P<0.01), hs-CRP (r=-0.768, P<0.01) or HOMA-IR (r=-0.752, P<0.01) were observed. The relationships between HOMA-IR and ICAM-1 (r=0.857,P<0.01), TNF-α (r=-0.906, P<0.01) or hs-CRP (r=-0.888,P<0.01) were positive.CONCLUSION: The results suggest that inflammatory refactors and adiponectin play important roles in the pathophysiology and progression of DR. The protective effects of adiponectin on DR may be related with its anti-inflammatory reactions to improve insulin resistant.     

Lipotoxicity of free fatty acid mixture and effect of free fatty acid mixture on lipid metabolism-related genes in L-02 cells

AIM：To investigate the lipotoxicity of free fatty acid (FFA) mixture and the effect of the FFA mixture on lipid metabolism-related genes in L-02 cells. METHODS：A normal human hepatocytes-derived cell line L-02 was treated with 0.5, 1 and 2 mmol/L FFA mixture (oleate and palmitate, 2∶1) for 24 h. The cellular total lipid accumulation was determined after Nile red staining by confocal laser scanning microscopy and flow cytometry. Intracellular triglyceride (TG) content was measured using an enzymatic kit. The viability of L-02 cells was determined by MTT assay and the apoptosis-inducing effect of FFA mixture was evaluated by annexin V/PI staining. The levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the culture medium were detected by ALT and AST kits. The mRNA levels of lipid metabolism-related genes, adipose differentiation-related protein (ADRP) and sterol regulatory element-binding protein 1 (SREBP-1), were examined by quantitative real-time PCR. RESULTS：All the different concentrations of FFA mixture increased intracellular lipid accumulation and TG content in a dose-dependent manner. FFA mixture at concentration of 1 mmol/L increased intracellular TG by 2.6 folds, which matched with the change in non-alcoholic fatty liver disease patients. Treatment for 24 h with 0.5 mmol/L and 1 mmol/L FFA mixture did not trigger apparent cell death and apoptosis, while treatment with 2 mmol/L FFA mixture resulted in a marked decrease in cell viability and induced early and late stages of apoptosis in L-02 cells. The levels of ALT and AST in the culture supernatant had no significant difference between control group and FFA treatment group. Treatment with 1 mmol/L FFA mixture up-regulated the expression of ADRP and SREBP-1 by 2.660 and 2.758 folds, respectively. CONCLUSION：FFA mixture induces the hepatic steatosis and 2 mmol/L FFA mixture causes mild cells damage in L-02 cells. The up-regulation of ADRP and SREBP-1 may be involved in FFA-induced hepatic steatosis.     

Role of Huoxue Jiangzhi Recipe in preventing and treating fatty liver in mice

AIM: To explore the role of Huoxue Jiangzhi Recipe in preventing and treating fatty liver in mice and its underlying mechanisms. METHODS: Healthy Kunming mice were fed with high-fat diet and treated intragastrically with different doses of Huoxue Jiangzhi Recipe (compound of ginseng, panax notoginseng and rhizoma gastrodiae, named as GST) for 2 weeks. The levels of blood lipids and triglyceride (TG) in hepatic tissues were measured. Meanwhile, liver index and hepatic pathology were observed. The optimized dosage of Huoxue Jiangzhi Recipe was determined by the experiments. The mice were divided into normal control group (NC group, fed with normal diet) and model group (fed with high-fat diet). The model mice were subdivided into 3 subgroups 12 weeks later: HF group (fed continuously with high-fat diet), ND group (fed with normal diet), GSL group (fed with normal diet and treated intragastrically with GSL). The mice in NC, HF and ND groups were given distilled water by gastric perfusion. Two weeks later, all mice were killed, and blood was collected for measuring serum total cholesterol (TC),TG,high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C) contents, hepatic TC, TG, malondialdehyde (MDA) levels and superoxide dismutase (SOD) activity were detected. Moreover, liver index and hepatic pathology were also observed. The mRNA expression of peroxisome proliferator-activated receptor alpha (PPARα) and cytochrome-P450 2E1 (CYP2E1) in the liver was examined by RT-PCR. RESULTS: GST significantly decreased serum lipid, hepatic lipid and MDA levels and elevated SOD activity. Furthermore, GST markedly reduced liver index, improved hepatic adipose infiltration, increased PPARα mRNA expression and inhibited CYP2E1 mRNA expression. CONCLUSION: GST is effective in the treatment of fatty liver in mice by up-regulating PPARα, thus reducing serum and hepatic TG levels, down-regulating CYP2E1 and inhibiting lipid peroxidation.     

Ginsenoside Rg1 improves liver function by regulating fat metabolism in rats with non-alcoholic fatty liver disease

AIM: To investigate whether ginsenoside Rg1 attenuates high-fat diet (HFD)-induced non-alcoho-lic fatty liver disease (NAFLD) by improving β-oxidation. METHODS: SD rats (n=60) were randomly divided into control group (CON), HFD group, low-dose, medium-dose and high-dose ginsenoside Rg1 groups (LDG, MDG and HDG) and positive drug (sodium ursodeoxycholate) treatment group (PDT). High-fat diet was given for 8 weeks to successfully establish an NAFLD model. The animals were treated with the appropriate medications for 4 weeks and 8 weeks after modeling, and sacrificed to collect the liver tissues for observing the pathologic changes with HE staining and for detecting liver functions and lipid levels. The expression of hepatic acyl-CoA synthetase 1 (CoASH1), carnitine acyltransferase I (CATI) and acyl-CoA oxidase 1 (ACOX1) at mRNA and protein levels was determined by RT-PCR and Western blotting. RESULTS: After 4-week treatment, the fatty infiltration of the liver tissues in PDT group, LDG group and MDG group was not attenuated except HDG group. After 8 weeks of treatment, a small number of fat particles was observed in PDT group and LDG group, while no infiltration of lipid droplet was found in MDG group and HDG group. Compared with HFD group, the levels of AST, ALT, AKP, TC, TG and LDL-C were significantly decreased after 4-week treatment in PDT group, LDG group, MDG group and HDG group (P<0.05), these indexes were further reduced after 8-week treatment. After 4-week treatment, HDL-C was significantly increased in the 4 treatment groups and almost restored to the level of CON group after 8-week treatment. The levels of CoASH1, CACTI and ACOX1 in the liver tissue of the 4 treatment groups were significantly increased after 4-week treatment (P<0.05) and much improved after 8-week treatment, and those in MDG group and HDG group were better than those in PDT group (P<0.05).CONCLUSION: Ginsenoside Rg1 regulates β-oxidation-related enzymes to improve the fat metabolism, thus playing a therapeutic role in liver injury in the rats with NAFLD.     

Serum apelin and chemerin levels in female obese children and their correlation with insulin resistance

AIM: To investigate the serum levels of apelin and chemerin in female obese children and their correlation with insulin resistance (IR).METHODS: Thirty-five female children participated in the study, 20 of which were obese and 15 were non-obese controls ,without statistical difference in age between the 2 groups. Serum levels of apelin and chemerin were measured by ELISA method. The concentrations of triglyceride (TG), cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), fasting glucose and fasting insulin (FINS) were measured. Body mass index standard deviation score (BMI-SDS) and homeostasis model assessment of insulin resistance (HOMA-IR) were calculated for all participants. RESULTS: A significant difference of BMI between obese group and control group (24.02±3.90 vs 16.46±1.93, P<0.01) was observed. Serum levels of TG, LDL-C, FINS, and HOMA-IR were significantly higher in obese group than those in control group (allP<0.05). Serum levels of apelin and chemerin were also significantly higher in obese children than those in the controls . Serum level of apelin was positively correlated with BMI-SDS (r=0.356, P<0.05), TG (r=0.548, P<0.01), FINS (r=0.541, P<0.01) and HOMA-IR (r=0.551, P<0.01) in all individuals. The negative correlation between serum chemerin level and age (r=-0.362, P< 0.05), and positive correlations between serum chemerin level and BMI-SDS (r= 0.315, P<0.01), TG (r= 0.28, P<0.05), FINS (r= 0.38, P<0.01) and HOMA-IR (r= 0.41, P< 0.01) were detected.CONCLUSION: Increased serum apelin and chemerin levels are correlated with insulin resistance, indicating their roles in the pathogenesis of children obese.     

Effect of salidroside on alcohol-injuced hepatic injury in rats

AIM:To investigate the effect of salidroside on alcoholic hepatic injury in rats. METHODS:The SD rats were randomly divided into 5 groups:negative control group, model group, bifendate group, and low-and high-dose salidroside groups. The rats in model group were administered with 56% alcohol, while the rats in negative control group was administered with saline. The rats in bifendate group and salidroside groups were administered with corresponding drugs every day. The blood and the liver tissues were collected to measure triacylglycerol (TG), alanine aminotransferase (ALT), aspartate aminotransferase (AST), malondialdehyde (MDA) and superoxide dismutase (SOD). The pathological changes of the liver tissues were observed with HE staining. Tumor necrosis factor-α (TNF-α) and nuclear factor-κB (NF-κB) were measured by ELISA and the protein and mRNA expression levels of TNF-α and NF-κB were detected by Western blot and RT-PCR. RESULTS:Compared with model group, the levels of TG, ALT, AST, MDA, TNF-α and NF-κB were reduced, while the activity of SOD was enhanced in salidroside group (P<0.05). The liver tissue injury was significantly attenuated. CONCLUSION:Salidroside improves the pathological changes, reduces inflammation, increases the activity of antioxidant enzymes and reduces lipid peroxidation in the liver with alcohol-induced injury. This effect may be related to regulating the NF-κB-mediated inflammatory responses.     

Effect of glucagon-like peptide 1 on Sesn2/AMPK/mTOR signaling pathway in liver of obese rats induced by high-fat diet

AIM: To explored the effect of glucagon-like peptide 1 receptor agonist liraglutide on Sesn2/AMPK/mTOR signaling pathway in the liver of obese rats.METHODS: Male SD rats were divided into normal chow (NC) group (n=12) and high-fat diet (HF) group (n=33). After 12 weeks, 5 rats of each group were used to assess establishment of obese rat model. The rats in HF group were divided into 4 subgroups, HF group, low dose of liraglutide (LG) group, middle dose of liraglutide (MG) group, and high dose of liraglutide (HG) group, and treated with various doses of liraglutide (0, 50, 100 and 200 μg/kg) via hypodermic injection twice a day for 4 weeks. The body weight and epididymal fat index of the rats at the 16th week were measured. The liver tissue fatty degeneration was observed. The protein levels of Sesn2, AMPK, p-AMPK, mTOR and p-mTOR were determined by Western blot.RESULTS: The body weight of rats in HF group was obviously higher than that in NC group (P<0.01). Compared with NC group, the levels of Sesn2 and p-AMPK/AMPK were significantly decreased in HF group (P<0.01), while the level of p-mTOR/mTOR was not changed. After treatment with liraglutide for 4-week, the body weight of the rats in LG, MG and HG groups was obviously lower than that in HF group (P<0.01), and epididymal fat index of the rats in MG and HG groups was obviously lower than that in HF group (P<0.01). The protein level of Sesn2 in HG group was obviously higher than that in HF group (P<0.01). The level of p-AMPK/AMPK was significantly increased in MG and HG groups (P<0.01). The level of p-mTOR/mTOR was significantly increased decreased in LG, MG and HG groups (P<0.01).CONCLUSION: Glucagon-like peptide 1 receptor agonist liraglutide affects energy metabolism and improves the state of obesity through Sesn2/AMPK/mTOR signaling pathway.     

Effect of berberine on oxidative damage and the SIRT1/p53 pathway in liver tissues of NAFLD rats

AIM:To investigate the effect of berberine on oxidative damage and silent mating type information regulation 2 homolog 1 (SIRT1)/p53 pathway in the liver tissues of nonalcoholic fatty liver disease (NAFLD) rats and to explore the mechanism of berberine against NAFLD. METHODS:The male SD rats (n=24) were randomly divided into normal group, model group and berberine group (8 rats in each group). The rats in normal group was fed with normal diet, while the rats in model group and berberine group were fed with high-fat diet. The rats in berberine group was intragastrically administered with daily doses (100 mg/kg) of berberine for 16 weeks. The levels of liver total cholesterol (TC), triglyceride (TG), superoxide dismutase (SOD), malondialdehyde (MDA) and total anti-oxidant capatity (T-AOC) were measured. HE staining, oil red O straining and transmission electron microscopy were used to observe the histological changes of the livers. The protein levels of SIRT1, p53 and acetylated p53 (Ac-p53) were determined by Western blot. RESULTS:Compared with model group, the levels of liver TC, TG and MDA in berberine group were significantly reduced (P<0.05 or P<0.01), and the levels of SOD and T-AOC were significantly increased (P<0.01). The results of pathological observation showed that the lipid accumulation in the liver of berberine group was significantly attenuated. Compared with model group, the expression of SIRT1 was significantly increased and the expression of Ac-p53 was obviously reduced in berberine group (P<0.01). CONCLUSION:Berberine reduces hepatic steatosis and oxidative damage in NAFLD rats induce by high-fat diet, and this effect may be associated with regulation of the SIRT1/p53 signal pathway.     

Effects of curcumin analogue L6H4 on myocardial tissue of type 2 diabetic rats

AIM: To explore the effects of curcumin analogue L6H4 on the myocardial tissue of type 2 diabetic rats and its mechanism. METHODS: Male Sprague-Dawley rats were randomly divided into normal control (NC) group, high-fat (HF) group, high-fat treatment (FT) group, diabetes mellitus (DM) group and diabetes treatment (DT) group.The rats in the latter 4 groups were fed high-fat diet for 4 weeks, then the rats in DM groups and DT groups were intraperitoneally injected with streptozotocin (STZ) to induce type 2 diabetes, while the rats in FT group and DT group were given L6H4. The blood glucose and lipid levels were detected by biochemical method, and serum adiponectin (APN) levels were detected by ELISA. The serum insulin levels were measured by radioimmunoassay and homeostasis model assessment of insulin resistance (HOMA-IR) were calculated. The morphological changes of myocardium were observed by Masson staining and electron microscopy. The protein expression of adiponectin receptor 1 (AdipoR1) and transforming growth factor β1(TGF-β1) in myocardial tissue were determined by immunohistochemistry. The protein expression of adipoR1 was also detected by Western blot for verification. RESULTS: Compared with NC group, the blood glucose, lipids, insulin, HOMA-IR and TGF-β1 were increased in HF and DM group, but they were decreased after treated with L6H4. Compared with NC group, the concentration of serum APN were decreased and the expression of AdipoR1 in the myocardium were weakened in HF group and DM group, and they increased after treated with L6H4. The myocardial fibrosis was obvious in HF group and DM group, the mitochondria in cardiomyocytes expanded, and the cristae disordered, partial disappeared. These lesions were significantly reduced after L6H4 treatment. CONCLUSION: L6H4 exerts a protective effect on the heart in type 2 diabetic rats. The increased concentration of serum APN, the enhanced expression of AdipoR1, and the expression of TGF-β1 inhibited by APN may be involved in the mechanism of protection.     

Effect of non-alcoholic fatty liver disease on metabolic syndrome-rela-ted type 2 diabetes

AIM: To investigate the effect of non-alcoholic fatty liver disease (NAFLD) on metabolic syndrome (MS)- related type 2 diabetes. METHODS: Sixty-four rats were randomly divided into 8 groups: normal control groups of 3 months (3NC), 6 months (6NC), 9 months (9NC) and 12 months (12NC), and high-sucrose and high-fat groups of 3 months (3H), 6 months (6H), 9 months (9H) and 12 months (12H). The serum levels of alanine transaminase (ALT), free fatty acid (FFA), endotoxin (LPS), tumor necrosis factor alpha (TNFα), C-reactive protein (CRP), monocyte chemotactic protein-1 (MCP-1), fasting plasma glucose (FPG) and fasting plasma insulin (FINS) were measured. The insulin resistance index (HOMA-IR) and beta cell function index(HOMA-β) were also calculated. The specimens of liver and pancreas were prepared for microscopic observation with HE and Sudan Ⅳ staining. The visceral adipose specimens were also prepared with HE staining. The apoptosis of islet cells was detected by TUNEL.RESULTS: Compared with normal control groups, the levels of ALT, FFA, LPS, TNFα, CRP, MCP-1, FPG, FINS and HOMA-IR in high-sucrose and high-fat groups of every phase were higher, but the level of HOMA-β in 6H group showed a compensatory increase first and then progressively decreased. Compared with normal control groups, TUNEL results showed that the number of apoptotic islet cells in high-sucrose and high-fat groups gradually increased from the 3rd to the 12th month. CONCLUSION: The NAFLD plays a trigger role in the start of MS-related type 2 diabetes.