[Dihydromyricetin improves Parkinson's disease-like lesions in T2DM rats by activating AMPK/ULK1 pathway].

The purpose of this study was to explore the effect and mechanism of dihydromyricetin (DHM) on Parkinson's disease (PD)-like lesions in type 2 diabetes mellitus (T2DM) rats. The T2DM model was established by feeding Sprague Dawley (SD) rats with high-fat diet and intraperitoneal injection of streptozocin (STZ). The rats were intragastrically administered with DHM (125 or 250 mg/kg per day) for 24 weeks. The motor ability of the rats was measured by balance beam experiment, the changes of dopaminergic (DA) neurons and the expression of autophagy initiation related protein ULK1 in the midbrains of the rats were detected by immunohistochemistry, and the protein expression levels of α-synuclein (α-syn), tyrosine hydroxylase (TH), as well as AMPK activation level, in the midbrains of the rats were detected by Western blot. The results showed that, compared with normal control, the rats with long-term T2DM exhibited motor dysfunction, increased α-syn aggregation, down-regulated TH protein expression, decreased number of DA neurons, declined activation level of AMPK, and significantly down-regulated ULK1 expression in the midbrain. DHM (250 mg/kg per day) treatment for 24 weeks significantly improved the above PD-like lesions, increased AMPK activity, and up-regulated ULK1 protein expression in T2DM rats. These results suggest that DHM may improve PD-like lesions in T2DM rats by activating AMPK/ULK1 pathway.

[Effects of dihydromyricetin on high fat diet induced obesity in mice and its mechanism].

OBJECTIVE: To observe the effects of dihydromyricetin (DHM) on obesity induced by high-fat diet in mice, and to explore whether its mechanism of action is related to the promotion of WAT browning. METHODS: Sixty c57bl/6j mice were randomly divided into 6 groups (n=10): ①normal control group (ND group): normal feed feeding; ②Normal control + low dose DHM group (ND+L-DHM group): normal feed feeding was treated with low dose DHM (125 mg/(kg·d)); ③Normal control + high dose DHM group (ND+H-DHM group): normal feed feeding was treated with high dose DHM (250 mg/(kg·d)); ④High-fat diet group (HFD): high-fat diet; ⑤high-fat diet + low-dose DHM group (HFD+L-DHM group): high-fat diet feeding with low-dose DHM; ⑥High-fat diet + high-dose DHM group (HFD+H-DHM group): High-fat diet was treated with high-dose DHM. After 16 weeks, the mice were fasted overnight, blood samples were collected for fasting blood glucose and blood lipids, then the animals were sacrificed, body length was measured, and Lee's index was calculated. After weighing the adipose tissue in the scapula, groin and epididymis, formaldehyde fixation and HE staining were used to observe the fat cells size, immunohistochemistry was used to detect the expression of uncoupling protein 1 (UCP1). The body weight was measured every 4 weeks during the experiment. RESULTS: Compared with the ND group, the body weight of the mice in the HFD group was increased significantly, suggesting that the obese mouse model replicated successfully. In addition, the body fat weight, fat cell diameter, Lee's index and blood glucose of the HFD group were increased significantly, and the expression of UCP1 in the adipocytes was increased. Body weight, fat cell diameter, Lee's index and blood glucose of HFD mice treated with L-DHM and H-DHM were reversed significantly, while the expression of UCP1 in adipocytes was more significantly increased; however, L-DHM and H-DHM had no significant effects on the above indicators in normal mice. CONCLUSION: Dihydromyricetin inhibited high fat diet induced mouse obesity; the mechanism might be associated with promoting WAT browning.

Potential regulatory mechanisms of lncRNA in diabetes and its complications.

Long non-coding RNAs (lncRNAs) are transcripts longer than 200 nucleotides without protein-coding potential. Although these molecules were initially considered as "junk products" of transcription without biological relevance, recent advances in research have shown that lncRNA plays an important role, not only in cellular processes such as proliferation, differentiation, and metabolism, but also in the pathological processes of cancers, diabetes, and neurodegenerative diseases. In this review, we focus on the potential regulatory roles of lncRNA in diabetes and the complications associated with diabetes.

[The effects of arecoline on the lipid metabolism of 3T3-L1 adipocytes].

OBJECTIVE: To observe the effects of arecoline on lipid metabolism in 3T3-L1 adipocytes and explore its possible mechanisms. METHODS: 3T3-L1 pre-adipocytes were induced into adipocytes with the classic "cocktail" method, subsequently, adipocytes were treated with arecoline at the concentrations of 0, 25, 50 and 100 µmol/L for 72 hours. After 72 hours, cell vability was measured with MTT method, lipid droplet accumulation in the cytoplasm was observed with oil red O staining, the protein expression of fatty acid synthase (FAS), adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) were detected by Western blot assay. RESULTS: There were a large number of lipid droplets in the cytoplasm in the differentiated 3T3-L1 adipocytes. MTT results showed that 0~100 µmol/L arecoline had no significant effect on cell vability; oil red O staining found arecoline reduced lipid amount in 3T3-L1 adipocytes; Western blot results showed that compared with 0 µmol/L arecoline group (the control group), arecoline significantly reduced the protein level of FAS and increased the protein levels of ATGL and HSL, and 50 µmol/L arecoline group was the most significant. CONCLUSIONS: Arecoline significantly increased lipolysis of 3T3-L1 adipocyte, which might be associated with decreased the FAS expression of key enzyme of lipid synthesis and increased the ATGL and HSL expression of key enzyme of adipolysis.

[The effects of dihydromyricetin on cognitive dysfunction in type 2 diabetes mice].

OBJECTIVE: To observe the effects of dihydromyricetin(DHM) on cognitive dysfunction and expression of brain derived neurotrophic factor(BDNF) protein in hippocampus of type 2 diabetic mice(T2DM). METHODS: Forty C57BL/6J mice were randomly divided into two groups, normal control group (n=8):normal diet feeding; T2DM model group (n=32):high-glucose and high-fat combined with 100 mg/kg streptozocin(STZ) treatment (five mice died during modeling and three failed). Twenty-four diabetic mice were modeled successfully and divided into three groups (T2DM group, T2DM+L-DHM group and T2DM+H-DHM group). Three groups mice were fed with high-glucose and high-fat diet, and treated with equal volume of normal saline, 125 mg/(kg·d) DHM or 250 mg/(kg·d) DHM for 16 weeks respectively. The control mice were fed with normal diet and treated with equal volume of saline (once a day, gavage) for 16 weeks. After 16 weeks, the body weight and fasting blood glucose were measured, intraperitoneal glucose tolerance test and related behavioral experiment were performed. Finally, the expression of BDNF protein in hippocampus of mice was detected by Western blot. RESULTS: The model of type 2 diabetes mellitus was established successfully with high-glucose and high-fat combined with 100 mg/kg STZ. After 16 weeks, the body weight of T2DM group was significantly decreased, the fasting blood glucose was significantly increased and the glucose tolerance was significantly abnormal compared with the normal control group. Compared with T2DM group, the body weight of T2DM+DHM groups mice was increased, while the levels of fasting blood glucose were decreased. And H-DHM could significantly improve the abnormal glucose tolerance of T2DM mice. Behavior test results showed that the ability of learning and memory of T2DM mice was significant decreased compared with control group, but these phenomena were improved in T2DM+DHM groups mice, and T2DM+H-DHM group was more obvious. Western blot analysis showed that the expression of BDNF protein in hippocampus of T2DM group was significantly lower than that of control group, while T2DM+DHM group was significant increased compared with T2DM mice. CONCLUSIONS: Dihydromyricetin can improve the cognitive dysfunction in type 2 diabetic mice. The mechanism may be through hypoglycemic effect and activation of BDNF protein expression in hippocampus.

[Ameliorative effects and the mechanism of lyceum barbarum polysaccharide on insulin resistance of HepG2 cell].

OBJECTIVE: To observe the effects of lyceum barbarum polysaccharide (LBP) on insulin resistance of HepG2 cells and investigate its possible mechanism. METHODS: IR-HepG2 cell model was induced with high glucose and high insulin in combination for 24 hours,with 104/vaccination in the 96-well plates, hole density after adherent cells (30 µg/ml、100 µg/ml、300 µg/ml) LBP cultivate 48 h, 200 µl/hole, each all had four holes. The effects of LBP at different concentrations on HepG2 cell activity and insulin resistance were tested. Intracellular malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were detected. The expressions of related proteins in insulin signal transduction pathways such as insulin receptor substrate-2(IRS-2), phosphatidylinositol-3-kinase(PI3-K), protein kinase B(Akt) and glucose transport-2(GLUT2) were determined. RESULTS: Compared with normal control group, the content of MDA was increased significantly and the activity of SOD and the expression levels of IRS-2,PI-3K,Akt and GLUT2 were decreased significantly in the IR model group. Compared with IR model group, medium and high concentrations of LBP decreased the content of MDA and increased the activity of SOD and the expression levels of IRS-2, PI-3K, Akt and GLUT2 in insulin-resistant HepG2 cells. MTT showed that at the same time, the OD value gradually decreased with the increase of LBP's concentration; under the same concentration of LBP, the OD value also gradually decreased with the extension of time, which indicated that LBP inhibited the proliferation of HepG2 cells with time and concentration-dependent manner. Glucose consumption experiment indicated that medium and high concentration of LBP could increase the glucose consumption of insulin-resistant HepG2 cells significantly, but low concentration of LBP had no significant impacted on glucose consumption of insulin-resistant HepG2 cells. CONCLUSIONS: Medium and high concentration of LBP can improve insulin resistance of HepG2 cell, its mechanisns may be associated with decreasing the level of oxidative stress and increasing the protein expressions of insulin signaling pathway.

[Effect of arecoline on proliferation and apoptosis of MCF-7 human breast cancer cells].

OBJECTIVE: To observe the effects of arecoline on proliferation and apoptosis of MCF-7 human breast cancer cells and to ex-plore its possible mechanism. METHODS: Human breast cancer MCF-7 cells were treated with arecoline at the concentrations of 0,10,30,50, 100,300,500µmol/L, the cell proliferation were detected by MTT assay, cell apoptosis were analyzed by Hoechst 33342 staining and flow cy-tometry, the protein expression of Bax,Bcl-2 and P53 were detected by Western blot. RESULTS: Low concentration(0,10,30, 50 µmol/L) arecoline had no effect on the proliferation and apoptosis of MCF-7. However, high concentration(100,300,500µmol/L) arecoline inhibited proliferation and induced apoptosis of MCF-7 cells in a concentration-dependent manner, arecoline also significantly increased P53 and Bax protein expression and decreased Bcl-2 protein expression. CONCLUSIONS: High concentration arecoline inhibited the proliferation and induced the apoptosis of MCF-7 cells, the mechanism was probably corrected with increasing P53 and Bax protein expression and decreasing Bcl-2 pro-tein expression.

[The role of arecoline on hepatic insulin resistance in type 2 diabetes rats].

OBJECTIVE: To explore the effects of arecoline on hepatic insulin resistance in type 2 diabetes rats and to elucidate its possible mechanism. METHODS: Forty five Wistar rats were fed with high fructose diet for 12 weeks to induce type 2 diabetic rat model. rats were randomly divided into 5 groups (n = 8): control group, model group and model group were treated with different dose (0, 0.5, 1, 5 mg/kg) of arecoline. After 4 weeks, the fasting blood glucose, blood lipid and insulin level measured , mRNA expression of liver constitutive androstane receptor (CAR), pregnane X receptor (PXR), glucose-6-phosphatase (G6Pase), phosphoenolpyruvate carboxykinase (PEPCK), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were detected by reverse transcription polymerase chain reaction (RT-PCR), the protein expression of p-AKT and glucose transporter4 (GLUT4) were detected by Western blot. RESULTS: 1.5 mg/kg arecoline could significantly decrease the level of fasting blood glucose, blood lipid, blood insulin level and liver G6Pase, PEPCK, IL-6, TNF-alpha mRNA level in type 2 diabetes rats. 1.5 mg/kg arecoline also could significantly increase CAR, PXR mRNA level and p-AKT and GLUT4 protein expression. CONCLUSION: Arecoline improved hepatic insulin resistance in type 2 diabetes rats by increasing the mRNA levels of CAR and PXR leading to the creased glucose metabolism and inflammation related genes expression.

Arecoline improves vascular endothelial function in high fructose-fed rats via increasing cystathionine-γ-lyase expression and activating K(ATP) channels.

AIM: To investigate the effect of arecoline, a major component of betel nut, on vascular endothelial function in high fructose-fed rats and the potential mechanisms underlying the effect. METHODS: Male Wistar rats were fed a high-fructose or control diet for 16 weeks. At the beginning of week 13, the rats were injected ip with low (0.5 mg·kg(-1)·d(-1)), medium (1.0 mg·kg(-1)·d(-1)) or high (5.0 mg·kg(-1)·d(-1)) doses of arecoline for 4 weeks. At the termination of the treatments, blood was collected, fasting blood glucose (FBG) and serum insulin (FSI) levels were measured, and insulin sensitivity index (ISI) was calculated. The thoracic aortas were isolated and aortic rings were prepared for studying ACh-induced endothelium-dependent vasorelaxation (EDVR). The mRNA and protein expression of cystathionine-γ-lyase (CSE) in the thoracic aortas was analyzed using RT-PCR and Western blot analysis, respectively. RESULTS: In high fructose-fed rats, the levels of FBG and FSI were remarkably increased, whereas the ISI and the mRNA and protein expression of CSE were significantly decreased. ACh-induced EDVR in the aortic rings from high fructose-fed rats was remarkably reduced. These changes were reversed by treatment with high dose arecoline. Pretreatment of the aortic rings rings from high fructose-fed rats with the CSE inhibitor propargylglycine (10 mmol/L) or the ATP-sensitive potassium (K(ATP)) channel blocker glibenclamide (10 mmol/L) abolished the restoration of ACh-induced EDVR by high dose arecoline. On the contrary, treatment with high dose arecoline significantly impaired ACh-induced EDVR in the aortic rings from control rats, and pretreatment with propargylglycine or glibenclamide did not cause further changes. CONCLUSION: Arecoline treatment improves ACh-induced EDVR in high fructose-fed rats, and the potential mechanism of action might be associated with increase of CSE expression and activation of K(ATP) channels by arecoline.

MicroRNA-375 promotes 3T3-L1 adipocyte differentiation through modulation of extracellular signal-regulated kinase signalling.

1. Adipocyte hypertrophy and hyperplasia are important processes in the development of obesity. To understand obesity and its associated diseases, it is important to elucidate the molecular mechanisms governing adipogenesis. MicroRNA-375 has been shown to inhibit differentiation of neurites, and participate in the regulation of insulin secretion and blood homeostasis. However, it is unknown whether miR-375 plays a role in adipocyte differentiation. 2. To investigate the role of miR-375 in adipocyte differentiation, we compared the miR-375 expression level between 3T3-L1 pre-adipocytes and adipocytes using miRNA microarray and quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) analysis. Furthermore, we evaluated the effects of overexpression or inhibition of miR-375 on 3T3-L1 adipocyte differentiation. 3. In the present study, we found that miR-375 expression was increased after induction of adipogenic differentiation. Overexpression of miR-375 enhanced 3T3-L1 adipocyte differentiation, as evidenced by its ability to increase mRNA levels of both CCAAT/enhancer binding protein-α (C/EBPα) and peroxisome proliferator-activated receptor-γ (PPARγ2), and induction of adipocyte fatty acid-binding protein (aP2) and triglyceride (TG) accumulation. Furthermore, we found overexpression of miR-375 suppressed phosphorylation levels of extracellular signal-regulated kinases 1/2 (ERK1/2). In contrast, anti-miR-375 increased ERK1/2 phosphorylation levels and inhibited mRNA expression of C/EBPα, PPARγ2 and aP2 in 3T3-L1 adipocyte, accompanied by decreased adipocyte differentiation. 4. Taken together, these data suggest that miR-375 promotes 3T3-L1 adipocyte differentiation, possibly through modulating the ERK-PPARγ2-aP2 pathway.

[miRNA expression change of differentiation of mice marrow mesenchymal stem cells into adipocytes].

OBJECTIVE: To explore miRNA expression change of differentiation of mice marrow mesenchymal stem cells (MSCs) into adipocytes, which lay the foundation for further studies on molecular mechanism of miRNA regulating the differentiation of MSCs into adipocytes. METHODS: C57BL/6 mice MSCs were isolated, cultured through the whole bone marrow method, amplified by the differential adherent method. Cell growth was observed by morphology and the expression of superficial antigen CD29, CD44, CD34 were detected through immunohistochemistry. MSCs was induced to differentiation into adipocytes with adipocyte differentiation medium, and adipogenic differentiation of MSCs was analyzed by oil Red O staining. MicroRNA microarray was used to investigate the differentially expressed miRNAs in MSCs and adipocytes. RESULTS: (1) The fifth passage of MSCs had high purity under an inverted m icroscope. Immunohistochemistry staining showed that CD29, CD44 were positive and CD34 was negative in more than 90% MSCs. There were a large number of lipid droplets in cytoplasm after MSCs were induced with adipocyte differentiation medium, Oil O staining was positive. (2) The microarray experiment showed that 75 differentially expressed miRNAs were obtained in adipocytes compared with MSCs, 20 up-regulated and 55 down-regulated miRNAs were observed among them. CONCLUSION: There was a expression change of miRNA of differentiation of MSCs into adipocytes, some miRNAs might play important roles in MSCs adipogenic differentiation.

Angiopoietin-1 protects myocardial endothelial cell function blunted by angiopoietin-2 and high glucose condition.

AIM: To evaluate the effects of angiopoietin-1 (Ang-1) on myocardial endothelial cell function under high glucose (HG) condition. METHODS: Mouse heart myocardial endothelial cells (MHMECs) were cultured and incubated under HG (25 mmol/L) or normal glucose (NG, 5 mmol/L) conditions for 72 h. MTT was used to determine cellular viability, and TUNEL assay and caspase-3 enzyme linked immunosorbent assays were used to assay endothelial apoptosis induced by serum starvation. Immunoprecipitation and Western blot analysis were used to analyze protein phosphorylation and expression. Endothelial tube formation was used as an in vitro assay for angiogenesis. RESULTS: Exposure of MHMECs to HG resulted in dramatic decreases in phosphorylation of the Tie-2 receptor and its downstream signaling partners, Akt/eNOS, compared to that under NG conditions. Ang-1 (250 ng/mL) increased Tie-2 activation, inhibited cell apoptosis, and promoted angiogenesis. Ang-1-mediated protection of endothelial function was blunted by Ang-2 (25 ng/mL). CONCLUSION: Ang-1 activates the Tie-2 pathway and restores hyperglycemia-induced myocardial microvascular endothelial dysfunction. This suggests a protective role of Ang-1 in the ischemic myocardium, particularly in hearts affected by hyperglycemia or diabetes.

CHANGES IN microRNA (miR) profile and effects of miR-320 in insulin-resistant 3T3-L1 adipocytes.

1. MicroRNAs (miRNAs) play essential roles in many biological processes. It is known that aberrant miRNA expression contributes to some pathological conditions. However, it is not known whether miRNAs play any role in the development of insulin resistance in adipocytes, a key pathophysiological link between obesity and diabetes. 2. To investigate the function of miRNAs in the development of insulin resistance, using miRNA microarray analysis we compared miRNA expression profiles between normal insulinsensitive 3T3-L1 adipocytes and 3T3-L1 adipocytes rendered insulin resistant following treatment with high glucose (25mmol/L) and high insulin (1 mol/L). Furthermore, adipocytes were transfected with specific antisense oligonucleotides against miRNA-320 (anti-miR-320 oligo) and the effects on the development of insulin resistance were evaluated. 3. We identified 50 upregulated and 29 downregulated miRNAs in insulin-resistant (IR) adipocytes, including a 50-fold increase in miRNA-320 (miR-320) expression. Using bioinformatic techniques, the p85 subunit of phosphatidylinositol 3-kinase (PI3-K) was found to be a potential target of miR-320. In experiments with anti-miR-320 oligo, insulin sensitivity was increased in IR adipocytes, as evidenced by increases in p85 expression, phosphorylation of Akt and the protein expression of the glucose transporter GLUT-4, as well as insulin-stimulated glucose uptake. These beneficial effects of anti-miR-320 oligo were observed only in IR adipocytes and not in normal adipocytes. 4. In conclusion, the miRNA profile changes in IR adipocytes compared with normal 3T3-L1 adipocytes. Anti-miR-320 oligo was found to regulate insulin resistance in adipocytes by improving insulin­PI3-K signalling pathways. The findings provide information regarding a potentially new therapeutic strategy to control insulin resistance.

Effects of rosiglitazone on the proliferation of vascular smooth muscle cell induced by high glucose.

AIM: To investigate the effects of the sensitizer rosiglitazone on the proliferation of vascular smooth muscle cell (VSMC) induced by high glucose administration. METHODS: VSMCs were isolated from rat thoracic aortas and cultured in 10% fetal bovine serum (FBS). VSMC proliferation was evaluated by methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay and cell counting. The cell cycle was examined by flow cytometry. The protein expressions of proliferating cell nuclear antigen (PCNA) and matrix metalloproteinases-2 (MMP-2) were evaluated by Western blotting. MMP-2 mRNA expression was analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and gelatinolytic activity was determined by zymography. RESULTS: Promoted VSMC proliferation significantly increased the number of VSMCs in the S phase, the expressions of PCNA and MMP-2, and MMP-2 activity, as well as decreased the proportion of VSMCs in the G(0)/G(1) phase. Rosiglitazone at a concentration of 10 mumol/L markedly inhibited glucose-induced VSMC proliferation (1.869 +/- 0.22 vs 0.820 +/- 0.15, P < 0.01). Concomitantly, rosiglitazone inhibited PCNA expression (0.96 +/- 0.07 vs 0.75 +/- 0.06, P < 0.05) and cell cycle progression from G(0)/G(1) to S phase (the proportion of VSMCs in the G(0)/G(1) and S phase were 69.6 +/- 3.96% vs 84.3 +/- 1.73% and 25.2 +/- 1.73% vs 10.1 +/- 1.42% (P < 0.01), respectively). Furthermore, rosiglitazone significantly decreased MMP-2 mRNA expression (0.98 +/- 0.08 vs 0.71 +/- 0.05, P < 0.05), protein expression (0.80 +/- 0.04 vs 0.64 +/- 0.03, P < 0.05) and MMP-2 activity (320 +/- 25% vs 248 +/- 21%, P < 0.05). CONCLUSION: Rosiglitazone significantly inhibited VSMC proliferation, at least in part by inhibiting high glucose-induced G(1)-->S phase transition, PCNA expression and MMP-2 synthesis.

Curcumin inhibits cellular cholesterol accumulation by regulating SREBP-1/caveolin-1 signaling pathway in vascular smooth muscle cells.

AIM: To investigate the protective effect and the possible mechanism of curcumin on anti-atherosclerosis. METHODS: Morphological changes of atherosclerotic lesions taken from apoE knockout (apoE-/-) mice were determined by hematoxylin- eosin staining. Intracellular lipid droplets and lipid levels were assayed by oil red O staining and HPLC. The protein expression of caveolin-1 was quantified by Western blotting. Translocation and the expression of sterol response element-binding protein-1 (SREBP-1) were indirectly detected by an immunofluorescence analysis. RESULTS: The administration of 20 mg. kg(-1 ). d(-1 )curcumin to apoE-/- mice for 4 months induced a 50% reduction of atherosclerotic lesions and yielded a 5- fold increase in the caveolin-1 expression level as compared to the model group. Rat vascular smooth muscle cells (VSMC) pretreated with 50 mg/L ox-lipid density lipoprotein(ox-LDL) for 48 h increased cellular lipid contents, and stimulated SREBP-1 translocation, but decreased the caveolin-1 expression level. Lipid-loaded cells exposed to curcumin at various concentrations (12.5, 25, and 50 micromol/L) for different durations (0, 6, 12, 24, and 48 h) significantly diminished the number and area of cellular lipid droplets, total cholesterol, cholesterol ester, and free cholesterol accompanying the elevation of the caveolin-1 expression level (approximately 3-fold); the translocation of SREBP-1 from the cytoplasm to the nucleus was inhibited compared with the models. Lipid-loaded VSMC exposed to N-acetyl- Leu-Leu-norleucinal, a SREBP-1 protease inhibitor, showed increased nuclear translocation of SREBP-1, reduced caveolin-1 expression level, and upregulated cellular lipid levels. CONCLUSION: Curcumin inhibits ox-LDL-induced cholesterol accumulation in cultured VSMC through increasing the caveolin-1 expression via the inhibition of nuclear translocation of SREBP-1.

[17ß-estradiol protects against injury of aortic relaxation and contraction in ovariectomized rats with insulin resistance induced by fructose].

The purpose of the present study was to investigate the effect of 17beta-estradiol (17beta-E(2)) on the structure and relaxation and contraction activity of thoracic aortas in ovariectomized rats with insulin resistance induced by fructose. Ovariectomized mature female Sprague-Dawley rats were fed with high fructose diet for 8 weeks to induce insulin resistance. Physiological dose of 17beta-E(2) (30 mug/kg) was injected subcutaneously every day for 8 weeks. Systolic blood pressure (SBP) was measured by use of tail-cuff. Serum nitric oxide (NO), estradiol (E(2)), fasting blood sugar (FBS) and fasting serum insulin (FSI) were measured respectively in each group. The insulin sensitive index (ISI) was calculated. The thoracic aortas were fixed in formalin, sliced and HE dyed. The structure of thoracic aortas, lumen breadth, media thickness, media thickness/lumen breadth ratio and media cross-section area were measured. The contraction response of thoracic aorta rings induced by L-phenylephrine (PE) and the relaxation response of thoracic aorta rings induced by ACh and sodium nitroprusside (SNP) were measured. To explore the mechanism, nitric oxide synthase (NOS) inhibitor N-nitro-L-arginine methyl ester (L-NAME) was used. The results obtained are as follows: (1) 17beta-E(2) protected against the effect of high fructose diet, which caused an increase in SBP, hyperinsulinemia and a decrease in ISI in ovariectomized rats. (2) The structure of thoracic aortas had no significant difference among the groups. (3) Compared with the ovariectomized group (OVX) or fructose fed group (F), serum nitric oxide was significantly reduced, the contraction response of thoracic aorta rings to PE was enhanced and the relaxation response to ACh was depressed significantly in ovariectomized+fructose fed group (OVX+F). The effect of high fructose was reversed by 17beta-E(2). After pretreatment with L-NAME, the effect of 17beta-E(2), which enhanced the relaxation response of thoracic aorta rings to ACh in ovariectomized+fructose+17beta-E(2) group (OVX+F+E(2)), was partly blocked. (4) The relaxation response of thoracic aorta rings to SNP had no significant difference among the groups. (5) The contraction response of thoracic aorta rings without endothelium to PE had no significant difference among the groups. These findings suggest that 17beta-E(2) may provide protection against the effect of high fructose diet, which causes hypertension, dysfunction of endothelial cells and insulin resistance. The mechanism of this effect of 17beta-E(2) could be partly associated with the increase of NO by NOS pathway, or associated with the decrease in the level of systolic blood pressure and serum insulin, and the improvement of insulin resistance.

[Effects of rosiglitazone on aortic function in rats with insulin resistant-hypertension].

Rosiglitazone (ROSI), thiazolidione peroxisome proliferator-activated receptor-gamma (PPAR-gamma) activator, reduces insulin resistance in patients with type 2 diabetes (T2DM). It also improves vascular reactivity in T2DM patients and some animal models by unclear mechanisms. In order to investigate the effect of ROSI on aortic systolic and diastolic function of insulin resistant-hypertensive rats (IRHR) and the underlying mechanism, male Sprague-Dawley (SD) rats were fed with high fructose (HF) for 8 weeks to induce IRHR model. To verify IRHR model, systolic blood pressure (SBP), fasting blood sugar (FBS), fasting serum insulin (FSI) were measured respectively in each group, and insulin sensitive index (ISI) was also calculated. Subsequently, the vascular function test was performed. The thoracic aortic ring of SD rats was mounted on a bath system. The effect of rosiglitazone on the contraction elicited by L-phenylephrine (PE) and potassium chloride (KCl) and the relaxation induced by acetylcholine (ACh) and sodium nitroprusside (SNP) were measured. To explore the mechanism, nitric oxide synthase (NOS) inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) was used and serum nitric oxide (NO) was measured. The results obtained were as follows: (1) Rosiglitazone reduced the level of SBP, serum insulin and improved insulin resistance in IRHRs. (2) The contractive responses of thoracic aortic rings to PE and KCl were enhanced and the relaxation response to ACh was depressed significantly in the HF group, and the effect was reversed by ROSI. (3) After pretreatment with L-NAME, the relaxation response to ACh was further impaired in the HF group, this effect was partly reversed by ROSI. (4) Sodium nitroprusside (SNP)-induced vasodilator responses did not differ significantly among the groups. (5) Aortic systolic and diastolic function of the control group was not affected markedly by ROSI. (6) Compared with the control group, serum nitric oxide was significantly reduced in the HF group, but after rosiglitazone treatment it was remarkably increased. These findings suggest that ROSI can improve aortic diastolic function of insulin resistant-hypertensive rats, the mechanism of this effect might be associated with an increase in nitric oxide mediated partly by NOS pathway, a decrease in the level of blood pressure, serum insulin and the improvement of insulin resistance.