Protective effects of pioglitazone on endothelial function in rats with hypercholesterolemia

AIM: To investigate the effects of pioglitazone,a PPARγ agonist,on endothelial cell (EC) dysfunction in hypercholesterolemic rats.METHODS: 36 healthy male Wistar rats were assigned to one of the following groups randomly (six rats in each group): control,hypercholesterolemia (HC),and HC treated with pioglitazone 1.5 mg·kg^-1·d^-1,3 mg·kg^-1·d^-1,10 mg·kg^-1·d^-1 and 20 mg·kg^-1·d^-1 (HC＋PIO),respectively.EC function was determined by comparing vasorelaxation to ACh,an EC dependent vasodilator,and acidified NaNO₂,an EC-independent vasodilator.Maximal positive and negative values of the instantaneous first derivative of LVP (+dp/dt_max and dp/dt_max) were determined by MS2000 system.RESULTS: (1) Hypercholesterolemia caused a significant endothelial diastolic dysfunction (maximal relaxation to ACh: 50.51%±2.45% vs 99.78%±3.01% in control,P<0.01).(2) Treatment with pioglitazone relieved EC-dependent vasodilatation in a dose dependent manner,and 10 mg·kg^-1·d^-1 is the best dose.(3) Pioglitazone not only improved EC function,but also reduced cardiac functional injury induced by hypercholesterolemia.CONCLUSION: EC dysfunction induced by hypercholesterolemia can be directly extenuated by pioglitazone,which may effectively prevent from subsequent atherosclerosis and ischemic heart disease.     

Administration of magnolol postpones development of hypertension in juvenile spontaneous hypertensive rats

AIM:To investigate the effects of magnolol (MAG) on blood pressure and aortic vasodilatation to insulin in juvenile spontaneous hypertensive rats (SHR). METHODS:Four-week-old male SHR and age-matched normotensive Wistar-Kyoto (WKY) control rats were used. SHR and WKY rats were randomized into 2 groups and treated daily by gavage with vehicle (distilled water) or MAG (100 mg·kg-1·d-1). After 3 weeks of treatment, blood pressure, aortic vasorelaxation, fasting glucose and plasma insulin levels, the expressions of PPARγ and TRB3, and insulin-stimulated Akt/endothelial nitric oxide synthase (eNOS) activation were measured. In vitro, human umbilical vein endothelial cells (HUVECs) were cultured in the medium containing glucose (25 mmol/L) and palmitate (500 μmol/L). RESULTS:Treatment of young SHR with MAG for 3 weeks decreased blood pressure, improved insulin-induced aortic vasodilation, and Akt and eNOS activation , increased PPARγ expression and decreased TRB3 expression. In cultured HUVECs, MAG incubation increased PPARγ exprssion, decreased TRB3 expression, and elevated insulin-induced phosphorylated Akt and eNOS levels and NO production, which were reversed by PPARγ antagonist. CONCLUSION: Treatment of young SHR with MAG at the prehypertensive stage decreases blood pressure via improving vascular insulin resistance that is at least partly attributable to up-regulation of PPARγ, down-regulation of TRB3 and consequently activation of Akt and eNOS in blood vessel .     

Effects of sesamin on blood fat,blood glucose and vascular remodeling in rats fed with high-fat and refined-sugar diet

AIM: To explore the effect of sesamin on blood fat, blood glucose and vascular remodeling in rats fed with high-fat, refined-sugar diet. METHODS: A high-fat, refined-sugar diet was given to rats for 24 weeks. Sesamin (120, 60, 30 mg·kg-1·d-1) was given by intragastric administration to the rats at 9th week, which lasted for 16 weeks. After 24 weeks, blood glucose, blood fat, blood pressure, activity of total anti-oxidation capacity (T-AOC) and concentration of hydrogen peroxide in serum and aorta were determined. Changes of histology and collagen fibers were observed in aorta by HE and Masson staining, respectively. Immunohistochemical method was used to examine iNOS protein expression in aorta. In mesenteric arteries, media thickness (M), luminal radius (L) and ratio of media to lumen (M/L) were measured. RESULTS: Compared to model group, sesamin (120, 60 mg·kg^-1·d^-1) obviously decreased the levels of blood glucose, blood fat, blood pressure and concentration of hydrogen peroxide in serum and aorta. Sesamin also markedly enhanced the activity of T-AOC in serum and aorta and reduced collagen deposition and iNOS protein expression in the vascular wall. In addition, proliferation of intima and vascular smooth muscle cells were improved. In mesenteric arteries, sesamin lessened M and M/L and increased L of mesenteric arteries. CONCLUSION: Sesamin ameliorates disorders of glucose and lipid metabolism and inhibits vascular remodeling in rats caused by chronic high-fat, refined-sugar diet.     

Role of endogenous nitric oxide synthase inhibitor in erectile dysfunction of diabetic rats

AIM: To investigate the role of nitric oxide synthase (NOS) inhibitor asymmetric dimethylarginine (ADMA) in erectile dysfunction of diabetic rats.METHODS: Type 2 diabetic rat model was established by 4 weeks of high-fat diet plus a single intraperitoneal injection of streptozotocin and continued high-fat diet feeding for 8 weeks. Corpus cavernosum was isolated from the rats under anesthetization, and the endothelium-dependent relaxation response to acetylcholine (ACh) was tested in an organ chamber to reflect erectile function. The level of ADMA in serum was detected. The NOS activity, nitric oxide (NO) content and cyclic guanosine monophosphate (cGMP) content in corpus cavernosum were measured. The protein expression of ADMA-NOS-NO pathway-related molecules and phosphodiesteras 5 (PDE5) in the corpus cavernosum was detected by Western blot. Superoxide dismutase activity and malondialdehyde content were analyzed to evaluate oxidative stress.RESULTS: Elevated blood glucose and lowered insulin sensitivity were observed in the diabe-tic rats, indicating that type 2 diabetic rat model was successfully established. Compared with control group, the relaxation response to ACh of corpus cavernosum from diabetic rats was significantly decreased, which was accompanied with the elevation of serum ADMA level and reduction of NOS activity, NO content and cGMP content in the corpus cavernosum. The protein expression of ADMA-generating enzyme protein arginine methyltransferase 1 was up-regulated, while ADMA-metabolic enzymes dimethylarginine dimethylaminohydrolases 1 and 2, and ADMA-targeting enzymes endothelial NOS and neuronal NOS were down-regulated. The protein expression of PDE5 was up-regulated, accompanied with an increase in oxidative stress in the corpus cavernosum of diabetic rats. Incubation of isolated corpus cavernosum from normal rats with NOS inhibitor ADMA induced the similar relaxation dysfunction of corpus cavernosum response to ACh and decreased NO and cGMP contents in diabetic rats.CONCLUSION: Elevated endogenous NOS inhibitor ADMA plays an important role in erectile dysfunction of diabetic rats. The underlying mechanism may be related to the reduction of NO production and the increase in oxidative stress.     

Effect of micronised fenofibrate on lipotoxicity and insulin sensitivity in spontaneously hypertensive rats treated with high-fat diet

AIM: To observe the effect of micronised fenofibrate (lipanthyl) on lipotoxicity and insulin sensitivity (IS) in spontaneously hypertensive rats (SHR) with high-fat diet.METHODS: Twenty-seven SHR were randomly divided into three groups: normal chow group (n=9), high-fat diet group (n=9) and micronised fenofibrate treatment group (n=9). Micronised fenofibrate 100 mg·kg-1·d-1 was given orally to SHR, which diet on high-fat diet for three months. Intramuscular lipids were observed and lipids accumulation index (LAI) was calculated. Nonesterified fatty acid, glucose and insulin were determined in all rats.RESULTS: (1) Compared to SHR in normal chow diet group, body weight and the level of serum TG and TC increased significantly and the level of HDL-C decreased significantly in SHR fed with high-fat diet (P<0.05). Micronised fenofibrate significantly decreased systolic blood pressure, body weight, the level of serum TG and TC, increased the level HDL-C (P<0.05). (2) Fasted blood glucose, free fatty acid (FFA), GLU-AUC obviously increased in high-fat diet group compared with normal chow diet group. Insulin sensitivity index (ISI) in high-fat diet group was much lower than that in normal chow diet group (0.0038±0.0007 vs 0.0053±0.0013, P<0.05). No difference was found between fenofibrate-treated group and normal chow diet group. (3) There were more lipid drops in intramuscular cells of SHR treated with high-fat diet than those in fenofibrate-treated group and normal chow diet group (LAI: 6.42±0.59 vs 3.32±0.77 and 1.98±0.97, P<0.05). After covariance analysis, the results above-mentioned also made sense (F=10.46, P<0.05). (4) Inverse association was found between LAI and ISI (r=-0.58, P<0.05). Positive correlations were found between LAI and TG, FFA, body weight.CONCLUSION: In addition to regulating lipid, micronised fenofibrate may reduce BP, body weight, FFA, lipid accumulation in intramuscular cells and improve insulin sensitivity of SHR treated with high-fat diet.     

Correlation of serum omentin-1 level and insulin resistance in rats

AIM：To establish the insulin resistance rat model for evaluating the correlation of omentin-1 level and insulin resistance. METHODS：SPF male Wistar rats (n=30) were randomly divided into normal control group (NC, n=15) and high-fat diet group (HF, n=15). The rats in NC group were fed with basic diet. The insulin resistant model was established by feeding the rats with high-fat diet in HF group. After 10 weeks, 5 rats in each group were assessed by the technique of hyperinsulinaemic-euglycaemic clamp. After the insulin resistant model was successfully established, the body weight and fasting blood glucose were detected. The concentration of fasting serum omentin-1 was analyzed by ELISA. Fasting serum insulin was measured by radioimmunoassay. RESULTS：No difference of fasting blood glucose between the 2 groups was observed. The level of fasting serum insulin in HF group was significantly higher than that in NC group (P<0.05). The level of serum omentin-1 in HF group were significantly decreased compared with NC group (P<0.01). Pearson’s correlation analysis showed that negative correlations between serum omentin-1 and fasting serum insulin (r=-0.654,P<0.01), serum omentin-1 and free fatty acid (r=-0.446, P<0.05) was found. CONCLUSION：In rats, serum omentin-1 level began to decrease at insulin resistance stage. As serum omentin-1 level decreased, the basal insulin level increased, indicating that decreased serum omentin-1 level may be an early factor of IR, diabetes and cardiovascular diseases.     

Preventive effect of 3,4-dihydroxyacetophenone on atherosclerosis and role of visfatin expression

AIM: To observe the preventive effect of 3,4-dihydroxyacetophenone (DHAP) on atherosclerosis (AS) and the role of visfatin expression in ApoE(-/-) mice.METHODS: Eight-week-old normal mice were used in normal control group (n=8). Eight-week-old male ApoE (-/-) mice were randomly divided into 3 groups: AS group (n= 8, im. NS), DHAP treatment group (n=8, im. DHAP 10 mg·kg^-1·d^-1) and simvastatin treatment group (n=8, im. simvastatin 10 mg·kg^-1·d^-1). All mice were fed with Western diet (21% fat, 0.15% cholesterol) for 12 weeks. The blood samples were collected and the concentrations of blood lipids and visfatin were detected. The frozen sections of aortic root were stained with oil red O. The visfatin in atherosclerotic plaques at aortic roots was examined by Western blotting. The structures of smooth muscle cells and endothelial cells were observed under electron microscope. RESULTS: In DHAP-treated mice, the concentrations of visfatin, TG and TC were decreased, the formation of AS plaque was reduced, the injuries of smooth muscle cells and endothelia cells were attenuated. Visfatin was also decreased at atherosclerosis plaque in DHAP-treated mice.CONCLUSION: DHAP effectively prevents and treats AS by inhibiting the production of visfatin and reducing lipid.     

Mechanism of hepatic insulin resistance induced by high-fat diet

AIM: To observed the relationship between oxidative stress and development of insulin resistance in hepatic tissues of Sprague dawley(SD) rats by analyzing reactive oxygen species(ROS) level and NADPH oxidase 3(NOX3) expression in livers. METHODS: Four-week-old male SD rats were fed with high-fat diet containing 20% fat and 20% sucrose for 12 weeks to induce insulin resistance. Plasma insulin level was detected by radioimmunoassay. The content of liver intracellular glycogen was measured using a glycogen assay kit. ROS generation in the liver tissues was assessed by dihydroethidium(DHE) fluorescence. The expression of NOX3 was determined by Western blotting.RESULTS: After 12 weeks of high-fat diet feeding, the content of blood glucose was increased but still maintained in normal level in the rats. However, the index of insulin sensitivity obviously decreased. Hepatic glycogen content in the rats fed with high-fat diet was significantly decreased, indicating that insulin resistance developed. Enhanced ROS production in hepatic tissues of the rats fed with high-fat diet was observed. Importantly, the expression of NOX3 in the liver was up-regulated in response to high-fat diet in vivo.CONCLUSION: High-fat diet feeding decreases insulin sensitivity, enhances ROS level and NOX3 expression, and reduces glycogen content in the livers.     

High-fat diet affects plasma membrane GLUT4 content in skeletal muscle from Sprague-Dawley rats

AIM: To explore the change of the amount of GLUT4 protein at the plasma membrane of the rat skeletal muscle after high-fat feeding. METHODS: The animals were divided into three groups (ten for each): group I: control; group II: high-fat feeding; group III: high-fat feeding + dietary treatment. The rat model of insulin resistance (IR) was made by feeding high-fat diet for eight weeks. And then insulin-resistant rats were fed with chow diet for 4 weeks. Fasting plasma glucose and fasting serum insulin levels were measured before and after dietary treatment, respectively. Insulin treatment was achieved by intraperitoneal injection of insulin (10 unit insulin per kg body weight) 15 minutes before killing the animals. The right hindlimb skeletal muscle was rapidly dissected. Then the expression of GLUT4 protein at the plasma membrane in all the animals was assessed with Western bloting. RESULTS: The GLUT4 content at the plasma membrane in high-fat-fed rat skeletal muscle was significantly lower (about 31%) than that in controls (P<0.01). Dietary treatment partly corrected fasting blood glucose [from(6.20±0.39)mmol/L to(5.78±0.74)mmol/L]and fasting serum insulin levels [from(17.19±1.93)mU/L to(11.68±1.28)mU/L] and increased the GLUT4 content at the plasma membrane by 1.14-fold in insulin-resistant rat skeletal muscle. CONCLUSION: High-fat feeding induces IR in Sprague-Dawley rats. The mechanism may be involved in decreased cell-surface level of GLUT4 through affecting intracellular insulin signaling and then decreasing GLUT4 trafficking.     

Effect of caveolin-1 expression on high-salt diet-induced endothelial dysfunction in type 1 diabetic rats

AIM: To investigate the underlying mechanisms responsible for endothelial dysfunction of type 1 diabetes mellitus (DM) rats fed with high-salt diet. METHODS: Type 1 DM was induced by intraperitoneal injection of streptozotocin (70 mg/kg). Normal and diabetic rats were fed high-salt food (HS, 8% NaCl) and standard food for 6 weeks, respectively. Isometric tension of the mesenteric arteries were measured. The expression of Akt, endothelial nitric oxide synthase (eNOS) and caveolin-1 (Cav-1) was examined by Western blot. RESULTS: The rats in DM+HS group exhibited more pronounced impairment of vasorelaxation to acetylcholine and insulin compared with either DM group or HS group (P<0.01). Akt and eNOS phosphorylation levels, and nitric oxide (NO) concentration in DM+HS group were significantly lower than those in DM group (P<0.01). The level of Cav-1 in DM+HS group was significantly higher than that in DM group and HS group. CONCLUSION: Impaired endothelial Akt activation, increased Cav-1 expression and resultant decreased eNOS activation contribute to aggravate high-salt diet-induced endothelial dysfunction and hypertension in DM rats.     

Protective effect of adiponectin on glucose and lipid metabolism by suppressing MHCⅡ expression

AIM: To investigate whether the protective effect of adiponectin on glucose and lipid metabolism is achieved through down-regulating major histocompatibility complex class Ⅱ (MHCⅡ) in the adipose tissue. METHODS: Adiponectin knockout (KO) mice and C57BL/6(WT) mice were fed with high-fat diet and standard diet for 24 weeks, respectively. The body weight, fasting blood glucose (FBG), fasting insulin (FINS), homeostasis model assessment of insulin resistance (HOMA-IR), triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), hepatic histology, and class Ⅱ trans-activator (CⅡTA), histocompatibility 2 class Ⅱ antigen E beta (H2-Eb1) and cluster of differentiation 74(CD74) mRNA and MHC Ⅱ protein levels in adipose tissue were measured at sacrifice. siRNA targeting MHC Ⅱ and overexpression vector was used in 3T3-L1 cells to explore the effect of adiponectin on the protein level of MHCⅡ. RESULTS: The levels of body weight, FBG, FINS, HOMA-IR, TC, TG, LDL-C, hepatic steatosis, CⅡTA, H2-Eb1 and CD74 mRNA expression, and MHCⅡ protein expression in the KO mice were higher than those in the WT mice that fed with high-fat diet or standard diet. In 3T3-L1 cells, inhibition of adiponectin reversed MHC Ⅱ protein level induced by specific siRNA. The expression of MHC Ⅱ in adipocytes decreased after adiponectin was overexpressed. CONCLUSION: Adiponectin improves glucose and lipid metabolism through suppressing the expression of MHCⅡ in the adipose tissue.     

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.     

Effects of extract of gingko biloba on the lipid metabolism and the function of macrophages from diabetic rats

AIM: To study effect of extract of ginkgo biloba (EGb) on the lipid metabolism and the function of macrophages from diabetic rats.METHODS: Sprague-Dauley rats were divided into four groups: normal control group, high-fat group, diabetic group and EGb treatment group.At the end of experiment, the rats were sacrificed, the blood glucose, blood insulin and serum lipid were measured.The activity of superoxide dismutase (SOD), content of malondialdehyde (MDA), nitric oxide (NO) in alveolar macrophages (AM) and peritoneal macrophages (PM) were assayed.In addition, peroxisome proliferator activated receptor γ (PPARγ), CD36 mRNA expression in AM was measured by RT-PCR.RESULTS: The concentration of the blood glucose, blood insulin and total cholesterol (TC), total triglycerides (TG), low-density lipoprotein- cholesterol (LDL-C) in blood increased significantly in type 2 diabetic group.The supplement of EGb decreased blood glucose, blood insulin and TC, TG, LDL-C levels.The activity of SOD decreased, while the content of NO, MDA increased in the diabetic macrophages, the activity of SOD became increased, but the content of NO and MDA decreased in EGb-treated group.The mRNA expression level of CD36 and PPARγ in alveolar macrophages from diabetic group increased, while expression level of CD36 and PPARγ mRNA in EGb treated rats continued to rise.CONCLUSIONS: EGb corrected insulin resistance and ameliorated disturbance of lipid metabolism caused by type2 diabetes in rats.Adjustment of PPARγ and CD36 mRNA expression of as well as reduction of lipid peroxidation and NO level may be involved in this process.     

Effect of Jia-jian-yi-yin decoction on endothelial dysfunction in ovariectomized female rats

AIM: To investigate the effect of Jia-jian-yi-yin decoction on endothelium-dysfunction in ovariectomized rats. METHODS: The ovariectomized rats were treated with Jia-jian-yi-yin decoction or turbid liquid of estradiol valerate for 8 weeks. The vascular ring tension was measured. Scanning electron microscopy and Western blotting were applied to assess the function of endothelium-dependent dilation, aortic endothelial morphology and the expression of endothelial lipase. The pathologic sections were prepared to observe the effect of Jia-jian-yi-yin decoction on the uterus. RESULTS: In ovariectomized rats, the decrease in endothelium-dependent relaxation to acetylcholine (ACh) was reversed to normal level, the endothelial morphology returned to normal without lipid accumulation and the endothelial lipase expression was decreased by Jia-jian-yi-yin decoction. Furthermore, no obvious change of the wet weight of uterine between the ovariectomized rats with or without Jia-jian-yi-yin decoction treatment was observed. CONCLUSION: Jia-jian-yi-yin decoction may have protective effects on endothelium-dependent vasodilation and aortic endothelial morphology in estrogen-deficient animals.     

Effect of GLP-1 on insulin resistance and PKCε in rats with nonalcoholic fatty liver disease induced by high fat diet

AIM: To observe the therapeutic effect of glucagon-like peptide 1 (GLP-1) analog on nonalcoholic fatty liver disease of rats and to investigate the underlying mechanism.METHODS: SD rats (n=21) were used to establish a nonalcoholic fatty liver disease model by feeding a high fat diet for 12 weeks, and other 11 rats were fed with a normal diet for 16 weeks. The model rats were randomly divided into 2 equal groups:one group was treated with glucagon-like peptide 1 analog (0.6 mg·kg^-1·d^-1) by intraperitoneal injection for 4 weeks, the other group using saline as a control. After treatment, fasting blood glucose, serum insulin, blood lipids, liver function and the pathological changes of the hepatic tissues were evaluated and the expression of PKCε at mRNA and protein levels in the liver tissues was detected by real-time PCR and Western blot, respectively.RESULTS: Compared with model group, the intervention of GLP-1 significantly reduced insulin resistance index (HOMA-IR), improved the liver function (P<0.05), decreased the liver index and blood lipids (P<0.05). HE staining showed obvious pathological changes of the hepatic tissues in model group, and the intervention of GLP-1 significantly reduced lipid droplets in the hepatocytes and improved the structural damage of the liver. The expression of hepatic protein kinase Cε (PKCε) at mRNA and protein levels significantly decreased which were reversed by treating with GLP-1.CONCLUSION: GLP-1 shows good therapeutic effect on nonalcoholic fatty liver disease of rats, possibly by controlling lipid metabolism and reducing insulin resistance, which may be related to PKCε expression.     

Atorvastatin inhibits atherogenesis by RXRα-mediated depressing oxidative stress in STZ-induced diabetic ApoE-/- mice with fat-rich diet

AIM: To explore the effects of atorvastatin (Atorv) on atherosclerosis in streptozotocin (STZ)-induced diabetic apolipoprotein E knockout (ApoE-/-) mice with fat-rich diet and the possible mechanism. METHODS：C57 mice served as control. ApoE-/- mice (n=34) fed with high-fat diet were randomly divided into ApoE-/- group, STZ-ApoE-/- group and STZ-ApoE-/-+Atorv group. Intraperitoneal injection of streptozotocin was performed to create diabetic animal model. Blood glucose was determined by glucose oxidase method. Blood lipid levels were detected by enzymic method or selective homogeneous method. The plaque area in the thoracic aorta was measured by HE staining. The protein level of nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase subunit gp91phox in the thoracic aorta was determined by Western blotting. The levels of reactive oxygen species (ROS) in blood and thoracic aorta homogenates were detected by Fenton reaction and Griess reagent. Human umbilical vein endothelial cells (HUVECs) were isolated from healthy umbilical cords by collagenase I and cultured. ROS production was detected by flow cytometry. NADPH oxidase activity was measured using lucigenin assay.Effects of retinoid X receptor α (RXRα) on inhibition of oxidative stress by atorvastatin were evaluated by RNA interference and plasmid transfection. RESULTS：(1) Compared with C57 group, the plaque areas of the thoracic aorta in ApoE-/- group were increased. No difference of the fasting glucose between the 2 groups was observed. The levels of triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), thoracic aorta gp91phox protein and ROS in blood and thoracic aorta homogenates were higher in ApoE-/- group than those in C57 group. (2) Compared with ApoE-/- group, the plaque areas of the thoracic aorta in STZ-ApoE-/- group were further enlarged ［(314.13±35.72) μm2 vs (215.88±34.19) μm2, P<0.05］. The levels of blood glucose, TG, TC and LDL-C, thoracic aorta gp91phox protein and ROS in blood and thoracic aorta homogenates were higher in STZ-ApoE-/- group than those in ApoE-/- group (P<0.05). (3) Compared with STZ-ApoE-/- group, the plaque areas of the thoracic aorta in STZ-ApoE-/- +Atorv group were reduced ［(217.47±24.56） μm2 vs （314.13±35.72） μm2, P<0.05］. The levels of blood glucose, LDL-C, TC, HDL-C and TG showed no significant difference between the 2 groups. Thoracic aorta gp91phox protein level and ROS production in blood and thoracic aorta homogenates were lower in STZ-ApoE-/- +Atorv group than those in STZ-ApoE-/- group (P<0.05). (4) High glucose-induced increases in NADPH oxidase activity and gp91phox expression were significantly inhibited by atorvastatin (10-6 mol/L) in HUVECs. The inhibitory effects of atorvastatin on high glucose-induced ROS production and NADPH oxidase activation were largely impaired when the cells were transfected with RXRα siRNA. However, the effect of atorvastatin was significantly strengthened when RXRα was over-expressed in the HUVECs transfected with RXRα plasmid. CONCLUSION：Atorvastatin inhibits atherogenesis by depressing high glucose-induced oxidative stress in diabetic ApoE-/- mice with fat-rich diet. The anti-oxidative stress effect of atorvastatin is mediated by RXRα.     

Effect of puerarin on blood pressure and serum lipid in a rat model of insulin resistance

AIM: To observe the effects of puerarin on blood pressure (BP), serum lipid in a rat model of insulin resistance and the mechanism. METHODS: Adult SD rats were maintained on high-fat-sugar-salt diet for 12 weeks. Puerarin was administered to the rats from 9th week for 4 weeks by intramuscular injection. BP was measured at the end of 0, 8th, 12th week. The levels of serum glucose, serum lipid, fasting serum insulin and the levels of MDA, TNF-α, plasma rennin, angiotensinⅡ (AngⅡ) and the activity of SOD were measured and the insulin-sensitivity index was also calculated at the end of the experiment. RESULTS: High and middle dosage of puerarin significantly decreased blood pressure, reduced the levels of serum lipid and AngⅡ, and also increased insulin-sensitivity index. The levels of MDA and TNF-α were significantly decreased by high dosage of puerarin. The activity of SOD was increased significantly. CONCLUSIONS: Puerarin possesses the effects of decreasing the blood pressure and serum lipid in a rat model of insulin resistance, which may be concerned with the changes of rennin- angiotensin system, the levels of oxygen-derived free radicals and TNF-α.     

Protective effect on hepatic insulin resistance of Astragalus polysaccharide in the high fat-fed mice model

AIM: To investigate the effect and mechanism of Astragalus polysaccharide (APS) on the amelioration of hepatic insulin resistance in high fat-fed mouse model.METHODS: C57BL/6J mice (n=26) were divided into three groups randomly: C group (an animal model for control,n=10);IR group ( an animal model of insulin resistance,n=8) and IA group (an animal model in high-fat diet with APS treatment for12 weeks,700mg·kg^-1·d^-1,ig).High-fat diet was used to induce the formation of insulin resistant.The parameters and insulin sensitivity of the animals were observed.The pathological features of the liver were presented through microscope and TEM.The expression changes of hepatic GSK3β were measured by Western blotting.RESULTS: In this study,the fat-fed mouse model of insulin resistance was established successfully.The mice in IA group responded to the 12-week APS therapy with a significant decrease in the level of blood glucose,plasma insulin,body weight,hepatic TG/FFA and improved glucose tolerance compared with those in IR group.In addition,the expression and the activity of GSK3β were lower in IA group (vs IR group，P<0.05).We also found the hepatic steatosis could be significantly alleviated with APS therapy.CONCLUSION: These results indicate that APS prevents the occurrence of insulin resistance and the hepatic steatosis induced by high-fat diet,at least in part by inhibiting the expression and activity of the hepatic GSK3β.     

The comparative study on SiNi-decoction and VitE against oxidative injury of vascular endothelial function and their preventive and therapeutic action on experimental atherosclerosis in rabbits

AIM: To compare effects of SiNi-decoction and Vitamin E on vascular endothelial function of experimental atherosclerosis rabbits and their therapeutic action on atherosclerosis.METHODS:The model of experimental atherosclerosis rabbits fed with forage of high lipid was established and treated in groups randomly. At the end of the experiment, samples of aorta and blood were taken and the percentage of lipid plaque area of aortic endothelium ,lipid metabolism and vascular endothelial oxidative injury (SOD activity, MDA content, NO level, endothelin concentration) of each group were analyzed. RESULTS: In comparison with model group,the percentage of the lipid plaque area of aortic endothelium and endothelial oxidative injury (except for SOD of VitE group) of SiNi-high and mid-dose group and VitE group are reduced obviously (P＜0.05),and the index of lipid metabolism of SiNi-decoction group is improved (P＜0.05). CONCLUSION:The comprehensive therapentic effects of SiNi decoction on vascular endothelial oxidative injury and atherosclerosis are superior to VitE.