Retarding effect of simvastatin on artery remodeling induced by high-salt and high-fat diet in rats

AIM: To investigate the effect of simvastatin intervention on the changes of blood pressure, serum lipid fluctuation and aortic configuration induced by high-sodium and high-fat diet in rats. METHODS: Sixty adult male SD rats were randomly divided into 5 groups (n=12): control (N)group, high salt (S)group, high fat (F) group, high salt+ high fat (SF) group and high salt+high fat + simvastatin (T) group. After fed for 16 weeks, the rats were subject to determine blood pressures and serum concentrations of triglycerides (TG),total cholesterol(TC) and soluble CD40 ligand (sCD40L). The expression of CD40/CD40L in the root of ascending aorta was detected by immunohistochemical method. The thickness of intima media in the ascending aorta as well as the ratio of lumen area/total vascular area were measured and calculated after HE staining. RESULTS: In S group, F group and SF group, systolic blood pressure was significantly higher than that in N group (P<0.01). Systolic blood pressure in T group were slightly higher than that in N group with statistical significance and significantly lower than that in SF group. The serum concentrations of TG and TC in F group and SF group were significantly higher than those in N group and T group (P<0.01), and no significant difference among S group, N group and T group was observed. In S group, F group and SF group, the serum concentrations of sCD40L were higher than that in N group and T group (P<0.05), meanwhile that in SF group was also higher than that in S group and F group (P<0.05). However, no significant difference of sCD40L concentration between S group and F group as well as N group and T group was observed. The expression of CD40/CD40L in the ascending aorta in S group, F group and SF group was higher than that in N group and T group (P<0.05), and that in SF group was also higher than that in S group and F group (P<0.05).No significant difference of CD40/CD40L expression between S group and F group as well as N group and T group was observed. The thickness of intima media in S group, F group and SF group was significantly thicker than that in N group (P<0.01), and no significant difference of the intima media thickness between T group and N group was observed. The ratio of lumen area/total vascular area in S group, F group and SF group was smaller than that in N group (P<0.05), and no significant difference of the ratio between T group and N group was found. CONCLUSION: Feeding high-fat and high-salt diet leads to blood pressure elevation, induces atherosclerosis, increases serum concentration of sCD40L and enhances the expression of CD40/CD40L in arterial tissues. The combination of the stimuli has stronger effect than a single factor. Statins protect the arterial tissues against atherosclerosis by decreasing the level of serum sCD40L and inhibiting the arterial expression of CD40/CD40L.     

Lipid metabolism is improved by L-carnitinein semi-starved rats fed on high fat diet

AIM: To investigate the effects of exogenous L-carnitine on lipid metabolism in semi-starved rats fed on high fat diet. METHODS: The semi-starved rats were restricted half in calorie intake on high fat diet for 2 week. L-carnitine was supplied at dose of 250 mg/kg·bw. The changes of plasma carnitine concentration, urinary excretion of ketone body, serum lipase activity, muscle carnitine palmitoyl transferase activity, triglyceride secretion and clearance rate were measured. RESULTS: The results showed that the concentration of plasma free carnitine increased significantly in carnitine supplemented rats compared to normal and semi-starved rats.The activities of muscle carnitine palmitoyltransferase and serum lipase were significantly enhanced in carnitine supplemented rats. The triglyceride secretion rate (TGSR) was also improved remarkably by carnitine supplementation. Meanwhile, the urinary excretion of ketone body was reduced significantly in carnitine supplemented rats compared to semi-starved rats. CONCLUSION: It is concluded that carnitine supplementation can significantly increase the plasma concentration of free carnitine and accelerate the lipid metabolism in semi-starved rats fed on high fat diet.     

Effects of oxidative stress on high-fat,high-salt diet and sucrose solution-induced metabolic syndrome in nephropathy rats

AIM: To establish a suitable animal model of nephropathy associated with metabolic syndrome (MS) induced by abnormal diet, and to investigate the effects of oxidative stress on renal damage in MS rats. METHODS: Normal 7-week-old male SD rats were randomly divided into 2 groups.The animals were fed with normal chow (control group, n=10) or high-fat and high-salt diet plus 20% sucrose solution (MS model group, n=10) for 20 weeks. Systolic blood pressure (SBP) was measured monthly. The levels of blood glucose, serum and urinary creatinine (Cr), total cholesterol (TC), triglycerides (TG), fasting insulin (FIns), urinary protein, urinary albumin and urinary sodium were determined. Insulin resistance (HOMA-IR), creatinine clearance (Ccr), urinary protein excretion (UPE), urinary albumin excretion (UAE) and urinary sodium excretion (USE) were calculated. Renal total-antioxidant capacity (T-AOC), inhibiting superoxide anion capacity (ISAC), malondialdehyde (MDA) content, and antioxidant enzyme activity were measured. Renal protein expression of Cu/Zn-SOD, NADPH oxidase subunit p47^phox and p22^phox was detected by Western blotting. In addition, pathological changes of the kidney were observed with PAS and Masson staining,and degree of glomerulosclerosis (GS) and tubulointerstitial injury was evaluated. RESULTS: Compared with control rats, SBP, TC, TG, FIns, USE and UAE were increased in MS rats. Furthermore, the MS rats showed a significant elevation of renal MDA content, p47^phox protein expression and GS score, and reduction of T-AOC, ISAC, SOD activity, and Cu/Zn-SOD protein expression in the kidney. CONCLUSION: SD rats fed with abnormal diet produce a suitable animal model of MS nephropathy that mimics the major features of human MS. Oxidative stress caused by up-regulation of NADPH oxidase expression and down-regulation of SOD expression may be one of the mechanisms leading to MS renal damage.     

Effects of grape seed procyanidin on vascular remodeling in renovascular hypertensive rats

AIM: To study the effect of grape seed procyanidin (GSP) on vascular remodeling in renovascular hypertensive (RH) rats. METHODS: The RH rat model was established by two-kidney one-clip method. Two weeks after operation, 28 rats were selected according to the increased tail systolic pressure above 130 mmHg and randomly divided into 4 groups (n=7): RH model group, low GSP treatment group (50 mg·kg^-1·d^-1),high GSP treatment group (200 mg·kg^-1·d^-1) and captopril treatment group (30 mg·kg^-1·d^-1). Meanwhile, 7 rats with sham operation served as controls. Tail systolic pressure, medial thickness (MT), luminal diameter (LD), and the ratio of MT to LD in thoracic aortic wall were determined 6 weeks after treatment. Masson staining and ELISA were used to detect the content of collagen and angiotensin II (Ang II) in aortic tissues. The protein expression of tumor necrosis factor α (TNF-α) in abdominal aortic tissues was determined by Western blotting. RESULTS: Compared with control group, the tail systolic pressure, MT, MT/LD, the content of collagen and the protein expression of TNF-α in aorta were significantly increased in RH model group, but LD decreased. Treatment with GSP and captopril reduced the raised parameters, and increased the LD in RH model rats. These effects were more notable in high GSP treatment group, and equal to captopril treatment group. CONCLUSION: GSP treatment significantly decreases tail systolic pressure in RH rats, and effectively attenuates arterial vascular remodeling by decreasing the content of AngII and reducing the protein expression of TNF-α in aorta.     

Pathways of local angiotensin II generation in islets of Langerhans in Syrian golden hamster fed with high-fat diet

AIM: To investigate the diverse pathways of local angiotensin Ⅱ (Ang Ⅱ) generation in islets of Langerhans in Syrian golden hamsters with dyslipidemia. METHODS: The Syrian golden hamsters were fed with high-fat diet to induce dyslipidemia. Purified islet cells from dyslipidemia and normal Syrian hamsters were prepared and divided into control group, captopril group, chymotrypsin endostatin group, aprotinin group, α-antitrypsin group and captopril+chymotrypsin endostatin group by adding respective reagents into the cultured cells after treated with angiotensin I. The Ang Ⅱ levels in the supernatants of each group were examined by ELISA.RESULTS: Compared with the control animals, Ang Ⅱ levels decreased in all groups with interventions. Compared with the normal hamsters islet cells, the Ang Ⅱ levels in captopril group, chymotrypsin endostatin group, α-antitrypsin group, aprotinin group and captopril+chymotrypsin endostatin group were decreased by 39.98%, 50.10% (P<0.01), 23.04%, 20.85% (P<0.05) and 82.78% (P<0.01), respectively. Compared with high-fat group, the corresponding data were 42.12%, 56.96% (P<0.01), 26.11%, 22.68% (P<0.05) and 83.59% (P<0.01), respectively. The levels of Ang Ⅱ in chymotrypsin group between normal and high-fat diet hamsters were significantly different (P<0.05). CONCLUSION: Under the condition of dyslipidemia, the classic angiotensin-converting enzyme-based pathway and chymotrypsin pathway are still the main approaches of producing Ang Ⅱ in male Syrian hamster islet to produce angiotensin. The effect of chymotrypsin endostatin is comparatively stronger in inhibiting the production of local Ang Ⅱ than the effect of angiotensin-converting enzyme inhibitor.     

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.     

Effect of lipoic acid on redox regulation,digestive and absorptive function in intestine of mice fed high fat diet

AIM:To elucidate the molecular mechanisms of lipoic acid (LA) on redox regulation and digestive function in intestine of C57BL/6 mice fed high fat diet (HFD).METHODS:C57BL/6 mice were randomly assigned to one of three groups (n=8).The control group consumed an ordinary diet.The other two experimental groups were fed with a high fat diet, high fat plus 0.1% LA.After 6 weeks, the activities of digestive enzymes were examined.In order to evaluate the antioxidant status of the mice, superoxide dismutase (SOD), malondialdehyde (MDA), total antioxidant capacity (TAC) and reactive oxygen species (ROS) in intestinal homogenate were measured.To investigate the molecular mechanisms underlying the effects of LA, the gene expression profiles in intestine were examined using the GeneChip microarray system.RESULTS:A depressed antioxidant defense system, accompanied by digestive and absorptive function impairment, was observed in HFD-fed mice.These changes were partially restored in the LA-treated group.DNA microarray analysis of intestine showed that LA ingestion up-regulated the expression of genes related to free-radical scavenger enzymes, digestive enzymes and transporters.CONCLUSION:Treatment with LA improves redox homeostasis and the function of intestine in mice fed HFD.The mechanism may involve preventing oxidative stress by scavenging ROS directly and increasing those of free-radical scavenger enzymes gene expression indirectly.     

Effects of short-chain acyl-CoA dehydrogenase on hypertensive vascular remodeling

AIM: To investigate the changes of short-chain acyl-CoA dehydrogenase (SCAD) in hypertensive vascular remodeling and to explore the relationship between SCAD and vascular remodeling in hypertension.METHODS: The spontaneously hypertensive rats (SHR; 24 weeks old) and Wistar rats (24 weeks old) were used as experimental control groups. The SHR and Wistar rats of 16 weeks old were trained by swimming as experimental groups. The systolic pressure was measured periodically. The thickness of vascular wall and the diameter of the vascular lumen were measured. The contents of ROS and ATP, the enzyme activity of SCAD, and the expression of SCAD at mRNA and protein levels in the aorta were determined. The free fatty acid in the serum and aorta was also measured.RESULTS: Compared with Wistar group, the diameter of vascular lumen decreased in SHR group. The thickness of vascular wall, the ratio of vascular wall and the diameter of vascular lumen, and the blood pressure in SHR group were increased significantly (P<0.05). Compared with SHR group, the diameter of vascular lumen increased in SHR+swim group. The thickness of vascular wall, the ratio of vascular wall and the diameter of vascular lumen, and the blood pressure in SHR+swim group were decreased significantly. Compared with control group, the expression of SCAD at mRNA and protein levels, the enzyme activity of SCAD, and the content of ATP were decreased in SHR group. However, the free fatty acid in the serum and aorta, and the content of ROS in the aorta were increased in SHR group. The expression of SCAD at mRNA and protein levels, the enzyme activity of SCAD, the content of ATP were increased in Wistar+swim group and SHR+swim group. However, the free fatty acid in serum and aorta, and the content of ROS in the aorta were decreased in Wistar+swim group and SHR+swim group.CONCLUSION: Decrease in SCAD expression may be associated with hypertensive vascular remodeling. Swimming training can reverse hypertensive vascular remodeling by increasing the expression of SCAD in the aorta.     

Effects of maternal high-fat diet on motor ability,learning and memory of male offspring mice in late adolescence

AIM To study the effects of maternal high-fat diet （HFD） on motor ability, learning and memory of male offspring mice in late adolescence and the underlying mechanism. METHODS The female rats were fed with HFD for 16 weeks until the end of lactation to establish the obesity model, and the offspring male rats were taken as the main research object. The motor coordination of offspring mice was studied by footprinting analysis and rotarod experiment, the change of motor ability of male offspring mice was studied by open field experiment, the change of learning memory behavior of offspring mice was studied by Morris water maze and new object recognition experiment, and the neurogenesis of dentate gyrus （DG） in hippocampus of offspring mice was observed by immunofluorescence staining. RESULTS The footprint angle of the offspring mice in maternal HFD group decreased significantly, and the stay time in rotarod of the offspring mice in maternal HFD group was significantly shorter than that of the offspring mice in maternal normal diet group（P<0.01）. In the open field experiment, the number of vertical times, the central time and the total distance of movement were significantly reduced, and the latency of water maze experiment and the preference index of new object recognition were significantly reduced. The results of immunofluorescence staining showed that the degree and complexity of neuron differentiation in DG area of hippocampus of offspring mice in maternal HFD group decreased significantly（P<0.01）. CONCLUSION Maternal HFD damages the movement and learning abilities of the male offspring in late adolescence by affecting the hippocampus neurogenesis.     

Renoprotective effects of sesamin on renal hypertensive and hyperlipidemic rats

AIM: To investigate the effects of sesamin on progression of renal injury in renal hypertensive and hyperlipidemic rats (RHHR). METHODS: RHHR was induced by 2K1C and high lipid baitvessel. After 7 weeks of intragastric administration with sesamin, the contents of serum creatinine (Scr), blood urea nitrogen (BUN), 24 h urinary protein excretion (UPE) were measured. In addition, the activity of total antioxidative capacity (T-AOC), superoxide dismutase (SOD), the concentrations of malondialdehyde (MDA), hydrogen peroxide (H2O2), and the nitric oxide synthase (NOS) and nitric oxide (NO) levels in renal homogenate were measured. RESULTS: Compared with the model group, seasamin (in 100 mg·kg-1 and 33 mg·kg-1 groups) evidently decreased the contents of Scr, BUN, UP and the concentration of MDA, iNOS, H2O2 in renal tissure. It also improved the levels of NO, cNOS and activity of SOD, T-AOC in renal tissure. CONCLUSION: Sesamin ameliorates hypertensive and hyperlipidemic-induced renal injury, probably by enhancing antioxidative activity, scavenging hydroxyl radical and restraining iNOS level.     

Effects of orexin-A on food intake and spontaneous physical activity in obesity-resistant rats and high-fat diet-induced obese rats

AIM: To investigate the differences of food intake and spontaneous physical activity (SPA) among obesity-resistant (OR) rats, diet-induced obese (DIO) rats and normal Sprague-Dawley (SD) rats and the role of orexin-A in these processes. METHODS: The rostral lateral hypothalamic area (rLHa) catheter was implanted into the OIO, OR, and SD rats. Orexin A at doses of 0, 31.25, 62.5, 125 and 250 pmol was injected through the catheter. The SPA and food intake were measured and recorded for 2 h after injection. The mRNA expression of prepro-orexin, orexin-A receptor (OX1R) and orexin-B receptor (OX2R) in the rLHa and hypothalamus of OR, DIO and SD rats was detected by real-time PCR. The protein expression of OX1R and OX2R in the hypothalamus and rLHa of the rats was measured by radioimmunoassay. RESULTS: A small-dose injection of orexin-A into rLHa significantly increased the food intake in all the rats. Orexin A-induced SPA had significant differences, showing that the OR and SD rats had the higher motion than the DIO rats. The mRNA and protein levels of OX1R and OX2R in the rLHa of OR rats were significantly higher than those in DIO and SD rats. CONCLUSION: Hypothalamic orexin-A participates in the regulation of energy metabolism in obese and normal rats, in which the regulatory effect on OR rats is the best.     

Effects of miR-124 over-expression on right ventricular remodeling in rats with pulmonary hypertension

AIM: To investigate the effect of microRNA-124 (miR-124) over-expression mediated by adeno-associated virus (AAV) on right ventricular remodeling in rats with pulmonary arterial hypertension (PAH) induced by monocrotaline (MCT). METHODS: Male SD rats (n=32) were randomly divided into 4 groups:normal control (control) group, MCT+normal saline (NS) group, MCT+AAV-GFP (MCT+GFP) group and MCT+AAV-miR-124 (MCT+miR-124) group. The rats in the latter 3 groups were instilled slowly with 100 μL NS, AAV-GFP and AAV-miR-124 by orotracheal instillation after anesthesia, respectively. Three weeks later, MCT (60 mg/kg) was intraperitoneally injected to establish the PAH model. Right ventricular systolic blood pressure (RVSP) and mean arterial pressure of the rats were measured, and right ventricular hypertrophy index (RVHI) and right ventricular weight index (RVWI) were calculated. The pathological sections of the right heart were stained with Sirius red, and the pathological changes of myocardium were observed under a microscope. The expression of miR-124 in the lung tissues was detected by RT-qPCR. The protein levels of transforming growth factor-β₁(TGF-β₁) and p-Smad2 in right heart tissues were determined by Western blot. RESULTS: Compared with control group, RVSP, RVHI, RVWI and the protein levels of TGF-β₁ and p-Smad2 in MCT+NS group and MCT+GFP group were significantly increased (P<0.05), the right ventricular myocytes were significantly enlarged, and collagen deposition was significantly increased. However, compared with MCT+GFP group, RVSP, RVHI, RVWI and the protein levels of TGF-β₁ and p-Smad2 in MCT+miR-124 group were significantly decreased (P<0.05), the degree of right ventricular myocyte hypertrophy was significantly reduced, and collagen deposition was significantly reduced. CONCLUSION: Over-expression of miR-124 obviously reduces RVSP of rats induced by MCT and relieves myocardial remodeling, which may be related to the down-regulation of TGF-β₁ and p-Smad2.     

Effects of blockade of rennin-angiotensin system on expression of uncoupling protein-2 and catalytic subunit of glutamylcysteine ligase in pancreatic islets in rats with insulin resistance and long-term high-fat diet

AIM: To study the mechanism of oxidative stress in rats characteristic of insulin resistance with long-term high-fat diet and to observe the effects of rennin-angiotensin system (RAS) blockade on the functions of RAS, oxidative stress and glucose metabolism.METHODS: Male Wistar rats were randomly divided into 4 groups: normal chow group (NC), high-fat-chow group (HF), perindopril treated group (FP, perindopril and high-fat-chow), and telmisartan treated group (FM, telmisartan and high-fat-chow). At the end of 16 week experiment, the last two groups were treated with perindopril 2 mg·kg-1·d-1 and telmisartan 10 mg·kg-1·d-1, respectively. After 8 week intervention, the glucose infusion rate (GIR) was measured by using euglycemic hyperinsulinemia clamp to evaluate the peripheral insulin resistance. Islet function of all the animals was evaluated by the intravenous glucose tolerance test. The mRNA expression levels of catalytic subunit of glutamylcysteine ligase (GCLC) in the islets were detected by RT-PCR. Immunohistochemical technique with qualitative and (or) quantitative analysis was applied to determine the expression of uncoupling protein-2 (UCP2) in the islets. The contents of malonaldehyde in the pancreatic tissue were determined by chromatometry.RESULTS: Compared to NC group, GIR in HF group was decreased by 31.8%, the relative expression of local GCLC was decreased by 31.5%，the relative content of UCP2 was increased by 17.0% (all P<0.01). The area under the curve of blood insulin between 0 and 10 minutes (AUCI0-10) was (271.8±33.8) vs (282.7±29.8) mIU·L-1·min-1, glucose-stimulated early insulin secretion was decreased, but there was no significant difference. Compared to HF group, the GIR of FP and FM groups was increased by 27.8% and 30.8%, respectively. The relative expression of local GCLC was increased by 26.6% and 26.6%, respectively, the relative content of UCP2 was decreased by 13.0% and 15.6%, respectively (all P<0.01). No significant difference between group FP and FM was found.CONCLUSION: Blockade of rennin-angiotensin system improves insulin resistance and pancreatic islet β-cell function in rats with long-term high-fat diet. The β-cell function may be protected by down-regulating the expression of uncoupling protein-2 (UCP2), up- regulating the expression of catalytic subunit of glutamylcysteine ligase (GCLC) and attenuating oxidative stress.     

Comparison of vascular remodeling between small artery and aorta in spontaneous hypertensive rats

AIM: To examine the difference of vascular remodeling between aorta and small artery in sponta-neous hypertensive rats (SHR) and control rats.METHODS: Male SHR (20-week-old) were used as experiment group, and age matched male Wistar-Kyoto (WKY) rats were used as control group. The systolic blood pressure and body weight were measured once a week. At 43 weeks old, the rats were anaesthetized, blood samples were collected, and thoracic aorta and mesenteric small artery tissue were harvested. The morphological changes of the arterial tissue were observed with HE staining. The collagen and elastine fibers were detected by the Sirius red-Victoria blue staining. The protein expression of type I and Ⅲ collagens were analyzed by confocal laser-scanning microscopy and Western blot. The changes of the vascular ultrastructure were imaged by transmission electron microscopy. The expression of proliferating cell nuclear antigen (PCNA) and the cell apoptosis in the arterial wall were examined by immunohistochemical method and TdT-mediated dUTP nick and labeling (TUNEL) detection.RESULTS: The inner diameter (ID) and luminal cross-sectional area (LCSA) of mesenteric small artery were decreased, whereas ratio of wall thickness (WT) to ID (WT/ID) and ratio of wall cross-sectional area (WCSA) to LCSA (WCSA/LCSA) were increased. Meanwhile, adventitia fibroblast migrated to the media, with overload collagens, especially collagen Ⅲ. Proliferation index (PI) and apoptotic index (AI) of the mesenteric small artery wall cells were increased. The ID, LCSA, WT/ID and WCSA/LCSA of the aorta were increased. Moreover, the vascular smooth muscle cells (VSMCs) showed hypertrophy and hyperplasia, with overload collagens. The PI and AI of the aortic wall cells were increased.CONCLUSION: The difference of vascular remodeling between the aorta and small artery is significant. The small artery mainly appears hyperplasia of matrix, especially the adventitial collagen Ⅲ. Meanwhile, the cell apoptosis in the small artery wall is increased. The aorta mainly appears hyperplasia and hypertrophy of media VSMCs.     

Effect of resveratrol on level of brain-derived neurotrophic factor in hippocampus of obese rats induced by ovariectomy and high-fat diet

AIM：To explore the effects of resveratrol on the level of brain-derived neurotrophic factor (BDNF) and the mRNA expression of estrogen receptor α (ERα) and estrogen receptor β (ERβ) in hippocampus of obese rats induced by ovariectomy and high-fat diet. METHODS：Fifty female Wistar rats, aged 3 months, were randomly divided into 5 groups: control (C) group, sham operation plus high-fat diet (H) group, ovariectomy plus normal diet (O) group, ovariectomy plus high-fat diet (O+H) group, and ovariectomy plus high-fat diet and treated with resveratrol (40 mg·kg-1·d-1) (O+H+R) group. Three months later, the blood was collected from the femoral artery to detect the serum concentrations of total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and estradiol (E2). The mRNA expression of ERα, ERβ and BDNF in the hippocampus was determined by real-time PCR. The protein level of BDNF in hippocampal tissues was detected by ELISA and Western blotting. RESULTS：Compared with C group, the serum levels of TC and LDL-C in H group were increased, and the hippocampal level of BDNF was decreased. The rats in O group had higher concentration of serum TC, and lower levels of serum E2 and the mRNA expression of ERα, ERβ and BDNF in the hippocampus than those in C group. Compared with C,H and O groups, the level of serum TC was higher, and the level of serum E2 and the expression of BDNF in the hippocampus was lower in O+H group. The mRNA expression of ERα and ERβ in hippocampus was also reduced as compared with C group and H group. After treated with resveratrol, the rats in O+H+R group showed lower level of serum TC, and higher levels of serum E2, hippocampal BDNF and mRNA expression of ERα and ERβ than those in O+H group. CONCLUSION：Ovariectomy combined with high-fat diet decreases the mRNA expression of ERαand ERβ and the level of BDNF in the rat hippocampus. Resveratrol improves the blood lipid metabolism and up-regulates the mRNA expression of ERα/ERβ and the level of BDNF in the hippocampus in obese rats induced by ovariectomy and high-fat diet.     

Effect of calories restriction on ER stress in the liver of high fat diet rats

AIM: To study the effect of calories restriction on endoplasmic reticulum(ER) chaperone protein 78-kD glucose regulated protein (GRP78) mRNA expression in the liver of high fat diet rats, in order to explore the mechanism of how calories restriction improves insulin resistance. METHODS: Wistar rats (n=24) were randomly divided into 3 groups: normal chow (NC) group, was fed free normal chow (18.94% of calories as fat) for 12 weeks; high fat group (HF) was fed high fat diet (50.55% of calories as fat) for 12 weeks; calories restriction group (CR) was fed high fat diet for 8 weeks at first, then given 50% of diet consumed by the same age NC group. Changes of body weight, height, and food intake were recorded. At the end of experiment, HOMAIR, the rate of visceral fat (including perirenal fat and epididymal fat) vs weight, plasma protein, blood lipid (including total cholesterol and triglyceride), hepatic GRP78 mRNA and hepatic histological changes (including light microscopic studies and electron microscopic studies) were detected. RESULTS: (1) Animals in HF group had an obviously elevation of fasting insulin (27.51±3.51) mU/L vs (15.46±2.25) mU/L, triglyceride (1.35±0.25) mmol/L vs (0.67±0.10) mmol/L, total cholesterol (2.59±0.34) mmol/L vs (1.41±0.28) mmol/L and insulin resistance index HOMAIR (5.85±0.23 vs 2.85±0.60) compared with NC group, and also had obviously lipid accumulations in the liver. (2) After calories restriction, all the abnormal elevated biochemical indicators were decreased to normal levels, the hepatic lipid accumulations were also improved. (3) The changes of liver ultrastructure in HF group showed rough endoplasmic reticulum enlargement, fragmentation, taking off grain, and with glycogen solution. The changes in CR group were nearly the same as those in NC group. (4) High fat diet induced the expression of GRP78 mRNA, calories restriction might reverse it. CONCLUSION: Reasonable food calories restriction is a good method to improve insulin resistance, partly due to improvement of endoplasmic reticulum stress in liver.     

Influence of high-fat environment on glucose metabolism in rat myoblasts

AIM: To explore the effects of high-fat environment on glucose metabolism in rat myoblasts. METHODS: The rat myoblasts were exposed to palmitic acid (PA) at concentrations of 0.1 mmol/L, 0.3 mmol/L or 0.5 mmol/L for 6 h, 12 h or 24 h. The viability of the cells was determined by MTT assay. The oil red O dyeing method was used to display triglyceride (TG) sediment in the cells. Triglyceride content in the cells was measured by glycerophosphate oxidase-peroxidase(GPO-POD) method. The uptake of 2-deoxy-D- glucose ( -G) in rat myoblasts was determined by isotope tracer method. RESULTS: After exposed to PA at concentrations of 0.1~0.5 mmol/L for 6~24 h, the viability of rat myoblasts decreased, TG sediment and content increased,and -G uptake was inhibited in a concentration-and time-dependent manner. Compared with control group, the cell viability, TG sediment and content, and -G uptake were significantly changed in 0.3 mmol/L PA group (24 h) and 0.5 mmol/L PA groups (12 h and 24 h). CONCLUSION: With the elevating concentration of PA exposure, TG sediment increases and glucose uptake decreases in rat myoblasts.