Effects of angiotensin II type 2 receptor blocker on wound healing in a mouse skin full-thickness injury model

AIM：To observe the effect of angiotensin II (Ang II) and its type 2 receptor (AT2R) on re-epithelialization, granulation tissue formation and growth factor production during wound healing, and to explore the possible mechanism by which Ang II and AT2R influence wound healing. METHODS：Two full-thickness skin wounds were created on the dorsum of C57BL/6J mice. The animals were treated with or without AT2R blocker PD123319 at a dose of 10 mg/kg daily after wounding. Specimens were taken from the wound of each mouse on days 3, 5, 7, 9, 11, 13 and 15 after wounding. Re-epithelialization and granulation tissue formation in the wounded skin tissues were evaluated by HE staining. The production of growth factors,epidermal growth factor (EGF),vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in wounded tissues during the healing process was detected by ELISA. RESULTS：Treatment with PD123319 significantly increased the rate of re-epithelialization and the area of granulation tissue compared with control group at 5 d and 7 d after wounding. Moreover, peritoneal application of PD123319 increased the production of EGF, VEGF and bFGF in the wounded tissues at the indicated time points after wounding. CONCLUSION：AT2R blocker PD123319 accelerates wound healing via promoting re-epithelialization,granulation tissue formation and growth factor production.     

Effect of NOS on podocytes in hyperlipidemia rats and the protection of simvastatin in podocyte damage

AIM: To investigate the possible effect of hyperlipidemia on golmerular podocytes,the nitric oxide synthase (NOS) availability and the synthesis of NOS in podocyte damage by hyperlipidemia,further to study the protective effect of simvastatin on podocytes.METHODS: 4 groups of Wistar rats were fed high fat diet for 18 weeks.Serum lipid,urinary protein excretion and renal pathological changes were detected.Immunohistochemistry was used to determine the expression of desmin.The expression of nNOS was detected by Western blotting.RESULTS: The level of serum lipid was increased significantly in hyperlipidemic group and treated group after 4 weeks (P<0.01) and was decreased significantly in simvastatin treated group compared with hyperlipidemic group (P<0.01).Podocyte injury was detected under electronic microscopy in hyperlipidemic group after 4 weeks,and the injury became more serious during the lasting time.The expression of desmin was increased in hyperlipidemic group after 4 weeks,and the level was significantly decreased in treated groups (P<0.01).The urinary protein excretion was increased significantly after 6 weeks (P<0.01),and the level was significantly lower in treated groups (P<0.01).The expression of nNOS was significantly decreased in hyperlipidemic and treated groups (P<0.01),and the level significantly decreased in simvastatin group (P<0.01).CONCLUSION: Hyperlipidemia induces podocyte injury.The injury seems to be associated with NO deficiency and decreased renal NOS activity.The injury can be relieved by simvastatin.     

Effects of gypenosides on PCSK9 gene expression and blood lipids lowered by simvastatin

AIM: To explore the effect of gypenosides (GPs) on PCSK9 gene expression in hyperlipidemic rat liver and the blood lipids lowered by simvastatin.METHODS: Healthy male SD rats (n=60) were randomized into 5 groups:normal control group, hyperlipidemic model group, simvastatin group, GPs group and GPs combined with simvastatin group (combined group). The rats in all groups were fed high-fat diet except normal control group which were fed with ordinary diet. The rats in control group and hyperlipidemic model group were gavaged with 0.3% CMC-Na every day. The rats in GPs group were gavaged with GPs at 160 mg·kg^-1·d^-1. The rats in simvastatin group were gavaged with simvastatin at 5 mg·kg^-1·d^-1. The rats in combined group were gavaged with GPs and simvastatin. The experiment lasted for 8 weeks. The rats were anesthetized with chloral hydrate, and abdominal arterial blood samples were collected to detect the total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C). The body weight and the wet weight of the livers were measured, and the liver index was calculated. The pathological changes of the livers were observed under microscope with HE staining. The expression of PCSK9 and low-density lipoprotein receptor (LDLR) at mRNA and protein levels was determined by real-time PCR and Western blot. RESULTS: The model of hyperlipidemia rats was established successfully. Compared with model group, the levels of TC, TG and LDL-C in simvastatin group, GPs group and combined group were obviously decreased (P<0.05), and the HDL-C levels were obviously upregulated (P<0.05). Compared with model group, the liver indexes in simvastatin group, GPs group and combined group were obviously decreased (P<0.05). The pathological changes of the liver tissues showed that hepatic adipose appeared in model group, and that in simvastatin group and GPs group had different degrees of relief, especially in combined group. Compared with model group, the mRNA expression levels of PCSK9 and LDLR in simvastatin group were obviously increased, while the mRNA expression levels of PCSK9 in GPs group and combined group were obviously decreased (P<0.05), and the mRNA expression of LDLR in combined group was obviously increased (P<0.05). Compared with model group, the protein expression of PCSK9 and LDLR in simvastatin group was obviously increased, while the protein expression levels of PCSK9 in GPs group and combined group were obviously reduced, and the LDLR protein levels were obviously increased (P<0.05). CONCLUSION: Gypenosides inhibit the expression of PCSK9 and increase the expression of LDLR in the liver. The combination of gypenosides and simvastatin promotes the lipid-lowering effect of simvastatin and attenuates hepatic steatosis, which may be related to inhibiting the expression of PCSK9 in the liver.     

Role of angiotensin II and angiotensin II receptors in vascular smooth muscle cells migration

AIM:To determine the effects of Angiotensin II(AngII) on migration of rat smooth muscle cells and to investigate the mechanisms underlying Ang II action in the development of injured vascular disease. METHODS:VSMCs isolated from aortic media of Wistar rats and cultured by the modified explant method were adopted. In prersence and absence of AngII, the expression of AngII receptor and reorganization of the actin cytoskeleton of VSMCs were studied by immunocytochemistry technique, fluorocytochemistry technique. The migration assays were performed by a modified Boyden's chamber. And the effects of AT₁R antagonist (CV-11974), AT₂R antagonist (PD123319) on aforementioned target were studied.RESULTS:VSMCs migration was stimulated by addition of AngII. The dynamic reorganization of actin cytoskeleton may be an important mechanism by which AngII facilitates VSMC motility. The expression of AT₁R in VSMCs can be upregulated after treatment with AngII initially, then decreased gradually. The expression of AT₁R was downregulated by AT₁R antagonist. The effect of AngII on VSMCs migration was mediated by AT₁R, while AT₂R had no significant effect.CONCLUSION:The dynamic reorganization of actin cytoskeleton is required for AngII-induced VSMC migration, and this effect is mediated by AT₁R .     

《中国科学技术专家传略》农学编.园艺卷2出版发行

AIM: To make hyperglycemia models and observe the effects of hyperglycemia on expressive type transformation of vascular smooth muscle cell (VSMC) in rats. METHODS: Using tissue culture and radioactivity analysis methods.RESULTS:①Hyperglycemia group was lower than control group in NO₂^- content, nitric oxide synthase activity and cGMP content;②Hyperglycemia group was higher than control group in endothelin, insulin, total chdesterol and [³H]-TdR penetrated rate of VSMC. CONCLUSION: It was possible that hyperglycemia reduces the expressive type of VSMC to change and promotes VSMC proliferation.     

Roles of nuclear factor-κB in the development of rat pancreatic fibrosis mediated by angiotensin II

AIM: To determine the effects of NF-κB on the development of rat pancreatic fibrosis mediated by angiotensin II. METHODS: Spraque-Dawley rats (200-300g) were randomly divided into normal group, control group and losartan-treatment group. Pancreatic fibrosis was induced by injection of 2% TNBS into biliopancreatic duct. Rats in losartan-treatment group and control group were respectively treated with losartan (10 mg·kg^-1·d^-1) by gavage and the same volume of saline vehicle. The expression, distribution, and activation of NF-κB were studied by Western blot, immunohistochemistry and TransAM^TM. Toluidine blue staining and transmission electron microscopy were also used to observe the number, distribution and degranulation of mast cells. In addition, RT-PCR was performed to detect the intrapancreatic ICAM-1 mRNA expression. RESULTS: The expression and activity of intrapancreatic NF-κB p65 protein were significantly increased on day 3 after operation, reaching peak on day 7 [(0.406±0.086)mg/g total protein].. Mast cell activation was observed and ICAM-1 mRNA levels on day 3 and 7 were up-regulated in control group. Losartan treatment inhibited NF-κB expression and activation, reduced mast cell infiltration and degranulation and decreased ICAM-1 mRNA expression compared with control rats. CONCLUSION: It might be associated with the expression and activation of NF-κB that angiotensin II mediates inflammation and fibrosis in the early stage of pancreatic fibrosis.     

Effect of taurine on L-arginine/NO pathway in erythrocytes of rats of hypertension with insulin resistance induced by fructose

AIM and METHODS:The present study observed the change of L-arginine(L-Arg)/Nitric oxide(NO)pathway in ergthrocytes in hypertension with insulin resistance rat induced by fructose and the effect of taurine on L-Arg/NO pathway.RESULTS:Drinking 4%fructose, while inducing blood pressure, glucose and plasma insulin contents increase, obviously decreased the maximal velocity of L-Arg transport about 31%and 37%(P<0.01), more than that of control group in total and Y⁺ carrier, the NO synthase(NOS)activity, nitrite(NO₂^-)content and cyclic guanylate monophosphate(cGMP)level more than that of control group, but obviously enhanced Michaelis Constant(Km)about 35%and 30%(P<0.01)more than that of control group in total and Y⁺ carrier transport.The taurine treatment significantly counteracted the above changes.CONCLUSION:There exists a functional disturbance in L-Arg/NO system in the erythrocyte of hypertension rats with insulin resistance, but taurine can obviously enhanced the maximal velocity of L-Arg transport and NOS activity.Thus, it appears that taurinemay have vital value in the treatment of hypertension with insulin resistance.     

Changes in the expression of endothelin system in rats with chronic heart failing

AIM: To study the changes of endothelin system during chronic heart failure (CHF) and imply the relationship between endothelin system and the course of CHF by observing the mRNA expression of endothelin receptors (ET_AR and ET_BR) and PreproET₁ in early stage and later stage of CHF caused by left coronary artery ligation. METHODS: The mRNA expression of ET_A, ET_B receptors and PreproET₁ were detected by RT-PCR technique. The plasma concentrations of ET₁ and ANP were determined by RIA method. RESULTS: The plasma concentrations of ET₁ and ANP, and the mRNA expression of ET receptors and PreproET₁ in the lefe ventricle increased significantly in early stage (myocardial infarction 10 d). While the plasma concentrations of ET₁ and ANP in later stage (myocardial infarction 70 d) were higher than those in the early stage. However, the mRNA expression of ET_AR, ET_BR and PreproET₁ decreased significantly. The mRNA expression of ET_AR in myocardial infarction (MI) 70 d rats had no difference with those in sham-operated rats and the mRNA expression of ET_BR and PreproET₁ in MI 70 d rats was lower significantly than those in MI 10 d rats, but significantly higher than those in sham-operated rats. CONCLUSION: The changes of ET receptors and PreproET₁ mRNA expression are involved in the cardiac function modulation during the different stages in chronic heart failure.     

The effect of glucocorticoid receptor on level of inflammatory media in rats after critical scald

AIM:To further elaborate the effect of glucocorticoid receptor(GR) decrease on level of inflammatory media in rats after critical scald.METHOD:The changes of phospholipase A₂(PLA₂) activity and concentrations of tumor necrosis factoralpha (TNFα) and malondialdehyde (MDA), the product of lipid peroxidation metabolism in plasma and tissue homogenate have been studied in scalded rats with or without GR blockade by RU38486.RESULTS:The PLA₂ activity and the concentrations of TNFα and MDA in plasma and homogenate of pulmonary and renal tissue in scalded rats were significantly higher than those in the controls(P＜0.01) and further increased in scalded rats accompanied with GR blockade (P＜0.01 or P＜0.05).CONCLUSION: Blockade of GR might aggravate the increase of inflammatory mediator caused by scalding. It suggested that GR might potentiate anti-inflammation in scald.     

Long-term effects of TCV116 on left ventricular remodeling and heart function after myocardial infarction in rats

AIM: To investigate the effects of long-term TCV116 on left ventricular remodeling and heart function after myocardial infarction. METHODS: Myocardial infarction (MI) was caused by ligation of the left anterior descending coronary artery in rats. One week after the surgical performance, the surviving rats were randomly assigned to the following treatment protocols: (1) MI rats with no therapy; (2) MI rats treated with TCV116 2 mg/kg per day; (3) Sham-operated control; (4) Sham-operated rats, treated with TCV116 2 mg/kg per day. At 22 weeks, cardiac hemodynamic parameters such as MAP, LVSP, dp/dt_max and LVEDP, and histomorphometric parameters such as LVW/BW and LVCA/BW were measured, mRNA of cardiac genes such as βMHC, BNP, TGF-β₁, collagen I and III were quantified, and survival rates were calculated. RESULTS: Compared with sham-operated rats, MI rats without therapy showed significant increases in histomorphometric parameters as well as in mRAN expressions of cardiac genes (P<0.01); While their hemodynamic parameters were significantly impaired (P<0.01), and survival duration shortened (P<0.05). Compared with MI rats without therapy, MI rats treated with TCV116 showed significant attenuation of mRAN expression of cardiac genes (P<0.01); While their hemodynamic parameters were significantly improved (P<0.05 or P＜0.01), and survival duration extended (P<0.05). CONCLUSION: Treatment with long-term angiotensin II type 1 receptor antagonist may improve left ventricular remodeling and cardiac function after MI in rats.     

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.     

The protective effects of angiotensin Ⅱ receptor blocker irbesartan on kidney function in diabetic rats

AIM: To investigate the effects and mechanisms of irbesartan, one of the angiotensin Ⅱreceptor blockers, on kidney function in diabetic rats. METHODS: Forty adult male Wistar rats were randomly divided into four groups: control group, diabetes group, irbesartan group and captopril group. At the end of 12 weeks, the rats were sacrificed. Urine volume, body weight, kidney weight/body weight, plasma, glucose, glycosylated hemoglobin (HbA₁c), urinary β₂-microglobulin (β₂-MG) excretion, urinary albumin excretion rate (UAR), creatinine clearance (Ccr) were measured. Nitric oxide (NO) and endothelin-1 (ET-1) levels in plasma, urinary and renal tissues were determined. RESULTS: Urine volume, kidney weight/body weight, plasma glucose, HbA1C, UAR, Ccr, urinary β₂-MG excretion, NO and ET-1 levels of urinary, blood and renal tissue in diabetic rats were significantly higher than those of normal controls ( P<0.01). UAR, Ccr, urinary β₂-MG excretion, ET-1 and NO levels of urinary and renal tissue in rats of irbesartan and captopril groups were significantly lower than those of DM rats ( P<0.01). There were positive relationships among the levels of plasma, urinary, renal tissue ET-1, NO and UAR, Ccr and urinary β₂-MG excretion. CONCLUSION: Irbesartan could prevent from the injury of renal function in STZ-induced diabetic rats. And it maybe one of the most importan mechanisms that irbesartan could reduce the NO and ET-1 levels in STZ-induced diabetic rats.     

Effect of erigeron on intercellular adhesion molecule-1 and its mRNA expression during cerebral ischemia and reperfusion in rats

AIM: To investigate the effect of erigeron on intercellular adhesion molecule-1 (ICAM-1) and mRNA expression during cerebral ischemia/reperfusion. METHODS: The rat models of middle cerebral artery (MCA) focal cerebral ischemic reperfusion were established with the suture method in the study. The ICAM-1 mRNA and protein expression were measured by RT-PCR and immunohistochemistry techniques, respectively. RESULTS: By down-regulating the expression of ICAM-1 protein and mRNA and alleviating inflammation in cerebral ischemic region, erigeron exerted a protective effect in cerebral ischemia and reperfusion. CONCLUSION: The results suggest that erigeron protects the brain against cerebral ischemia and reperfusion injury via inhibiting ICAM-1 expressino.     

Effect of simvastatin on expression of Toll-like receptor 2 in mouse cytomegalovirus pneumonia

AIM: To investigate the effects of simvastatin on the expression of Toll-like receptor 2 (TLR-2), interferon-γ (IFN-γ) and monocyte chemoattractant protein-1 (MCP-1) in lung tissues of mice with mouse cytomegalovirus (MCMV) pneumonia and to explore the possible mechanism. METHODS: Male BALB/c mice (6~8 weeks old, n=40) were randomly divided into 5 groups: normal control (NC) group, MCMV infection group, simvastatin group 1 (SMV1 group), simvastatin group 2 (SMV2 group), and simvastatin group 3 (SMV3 group). The mice in SMV1, SMV2 and SMV3 groups were gavaged with simvastatin (50 mg·kg^-1·d^-1 for 7 d) 7 d before, on the same day of and 3 d after intraperitoneal injection of MCMV, while the mice in normal control group and MCMV infection group were gavaged with the same volume of normal saline. HE staining was used to observe the pathological changes of lung tissues in mice. Total tissue protein was extracted from the lung homogenates to detect the expression of TLR-2 by Western blot and immunohistochemical staining. Real-time PCR was used to analyse the content of MCMV DNA. The levels of IFN-γ and MCP-1 were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: Compared with NC group, the pathological changes of the lung tissues of the mice in MCMV group showed alveolar interstitial edema, alveolar wall widening and a large number of inflammatory cells. The expression of TLR-2 in the lung tissues of the mice in model group was increased significantly. The content of MCMV DNA was increased, and the expression of IFN-γ and MCP-1 was also increased significantly. Compared with the mice in MCMV group, the pathological changes of the lung tissues of simvastatin groups showed that the inflammatory cells were decreased. The expression of TLR-2 was down-regulated. The content of MCMV DNA was decreased, and the levels of IFN-γ and MCP-1 were also decreased significantly. At the same time, the expression of TLR-2 and the content of MCMV DNA in SMV1 group were less than those in SMV2 and SMV3 groups (P<0.05), and no statistically significant difference between SMV2 and SMV3 groups was observed. CONCLUSION: Simvastatin down-regulates the TLR-2 signaling pathway, and reduces the expression of TLR-2 and replication of MCMV DNA, thus attenuating the pathological damage of the lung tissue. Early intervention with simvastatin plays an important role in preventing the infection of MCMV and reducing the inflammation.     

Effects of taurine-magnesium complex on vascular endothelium and hemorheology in rats in vivo

AIM: To study the protective effects of taurine-magnesium complex (TMC) on endothelium and hemorheology in rats. METHODS: A model of the endothelial damage was made by means of giving rats an injection of adrenaline and making them swim in ice-cold water, then number of circulating endothelial cells (CEC) in whole blood, plasma ET-1 and NO₂^-/NO₃^- content, NOS activity and rheology were determined, respectively. The protective effects of TMC were also observed. RESULTS: An increase in the number of CEC accompanied by abnormal whole blood viscosity, and endothelium-derived ET-1 were observed in model rats. Both the NO₂^-/NO₃^- content and NOS activity were declined significantly in model rats. TMC reduced the number of CEC, resumed NO₂^-/NO₃^- content and NOS activity, and improved the whole blood viscosity in a dose-dependent manner in model rats. CONCLUSION: Ice-cold water bath with adrenaline causes an acute damage of vascular endothelium and abnoramal rheology. TMC protects against the injury of vascular endothelium and improves the hemorheology.     

The alteration of expression of iNOS mRNA and ecNOS mRNA in peripheral leukocytes from insulin resistance rats fed with fructose

AIM: To study the alteration of expression of iNOS mRNA and ecNOS mRNA in peripheral leukocytes of Wistar rats fed with fructose. METHODS: Wistar rats were randomly divided into the control group (n=10) and the fructose feeding group(n=10). The fructose feeding group drank12% fructose water for 6 months. The blood glucose, blood insulin, and the expression of iNOS mRNA and ecNOS mRNA in peripheral leukocytes of rats were determined. RESULTS: The levels of blood insulin (P<0.01) and the expression of ecNOS mRNA were higher in fructose feeding group than that in control group after1month. The level of blood insulin(P<0.01), the level of blood glucose (P<0.05), the expression of ecNOS mRNA and the iNOS mRNA were also higher in fructose feeding group than that in control group after 2 months. The levels of blood insulin and glucose, the expression of ecNOS mRNA and the iNOS mRNA were increased persistently during 3 to 6 months. CONCLUSIONS: These results indicate that fructose can increase the level, but reduce the sensitivity of insulin. It can also induce the expression of ecNOS mRNA firstly and the expression of iNOS mRNA secondly, the former can delay the formation of insulin resistance and the later can accelerate the formation of insulin resistance.     

Effect of insulin on the secretion of VEGF and its receptor in serum-free cultured bovine thoracic aortic endothelial cells

AIM: This study was designed to investigate the secretion of VEGF and its receptor (flt-1 or flk-1/KDR) protein by cultured bovine thoracic aortic endothelial cells treated with various insulin concentrations. METHODS: Endothelial cells was isolated from bovine thoracic aorta, and cultured in serum-free medium, then incubated with different insulin concentrations (30 mU/L, 300 mU/L, 3 000 mU/L). The level of VEGF and its receptor (flt-1 or flk-1/KDR) protein were detected by immunohistochemical staining. RESULTS: As compared with no insulin group, the expression of VEGF protein in low insulin concentration (30 mU/L and 300 mU/L) groups were significantly increased (P＜0.01). The expression of VEGF protein in high insulin concentration (3 000 mU/L) group was significantly decreased (P＜0.05). Howerer, no difference of the expression of VEGF receptor (flt-1 or flk-1/KDR) protein among all groups (P＞0.05) was observed. CONCLUSION: Low concentration insulin up-regulates the VEGF protein expression while high concentration insulin down-regulates the VEGF protein expression in bovine thoracic aortic endothelial cells, but insulin had no directly effect on the VEGF receptor (flt-1 or flk-1/KDR) protein expression in bovine thoracic aortic endothelial cells.