Simvastatin inhibits leptin-induced hypertrophy in cultured neonatal rat cardiomyocytes

AIM: To test the hypothesis that statins inhibit leptin-induced hypertrophy in cultured neonatal rat cardiomyocytes. METHODS: Cultured neonatal rat cardiomyocytes were used to evaluate the effects of simvastatin on leptin-induced hypertrophy. Intracellular reactive oxygen species (ROS) levels were determined by using 2',7'-dichlorofluorescein diacetate (DCF-DA) fluorescence. Total intracellular RNA and cell protein content, which serve as cell proliferative markers, were assayed by using propidium iodide (PI) fluorescence and the Bio-Rad DC protein assay, respectively. The cell surface area, an indicator of cell hypertrophy, was quantified by using Leica image analysis software. RESULTS: After 72 h treatment, leptin markedly increased RNA levels, cell surface area, and total cell protein levels in cardiomyocytes, which were significantly inhibited by simvastatin or catalase treatment. ROS levels were significantly elevated in cardiomyocytes treated with leptin for 4 h compared with those cells without leptin treatment. The increase in ROS levels in cardiomyocytes induced by leptin was reversed by treatment with simvastatin and catalase. CONCLUSION: Simvastatin inhibits leptin-induced ROS-mediated hypertrophy in cultured neonatal rat cardiac myocytes. Statin therapy may provide an effective means of improving cardiac dysfunction in obese humans.     

Simvastatin inhibits noradrenaline-induced hypertrophy of cultured neonatal rat cardiomyocytes

1. Oxidative mechanisms have been implicated in neonatal cardiomyocyte hypertrophy. We and others have shown that a HMG-CoA reductase inhibitor preserves endogenous antioxidant enzyme activity and inhibits cardiac hypertrophy in vivo. We therefore have examined whether noradrenaline (NA) induces the generation of reactive oxygen species (ROS) during its induction of neonatal cardiomyocyte hypertrophy and whether simvastatin, a HMG-CoA reductase inhibitor, attenuates ROS production and thus NA-induced hypertrophy of cardiomyocytes. 2. NA increased the intracellular ROS levels in a concentration-dependent manner. This increase of ROS was significantly inhibited by simvastatin and catalase. Prazosin partially suppressed NA-induced increase of ROS and beating, while preincubation with both prazosin and propranolol completely abolished NA-evoked increase of ROS and beating. Simvastatin did not affect NA-induced increase of beating. 3. The NA-induced increase of protein content was partially suppressed by prazosin and completely abolished by preincubation with both prazosin and propranolol. Simvastatin inhibited the increase of NA-induced increase of RNA content and [(3)H]-leucine incorporation in a concentration-dependent manner. Mevalonic acid (MVA) reversed the inhibition of NA-induced RNA and protein increase by simvastatin. Catalase also inhibited the NA-induced increase of RNA and protein. 4. We conclude that the inhibitory effects of simvastatin on myocyte hypertrophy were associated with its antioxidant effects and inhibition of MVA-metabolism pathway in neonatal rat cardiomyocytes. NA-induced increases of intracellular ROS and cardiomyocyte hypertrophy requires both alpha and beta adrenoceptors activation in neonatal rat cardiomyocytes. The increases of ROS induced by NA is required for hypertrophy.     

槲皮素对血管紧张素Ⅱ致培养乳鼠心肌细胞肥大的抑制作用

目的:研究槲皮素(Quercetin,Que)对血管紧张素Ⅱ(Aug Ⅱ)诱发培养乳鼠心肌细胞肥大的抑制作用及机制。方法:分别用[~3H]胸苷、[~(14)C]尿苷和[~3H]酪氨酸标记测定DNA、RNA和蛋白质合成;用Lowry法测定蛋白质含量;用组蛋白ⅢS、[γ-~(32)P]ATP与蛋白激酶C(PKC)酶液一起保温测定PKC活性;用聚谷氨酸·酪氨酸(4:1)多肽、[γ-~(32)P]ATP与酪氨酸蛋白激酶(TPK)酶液一起保温测TPK活性。结果:Aug Ⅱ作用于心肌细胞24h后,心肌细胞总蛋白含量明显增加(P<0.01),[~(14)C]尿苷和[~3H]酪氨酸掺入量明显增加(P<0.01),而[~3H]胸苷掺入量未见增加(P>0.05);Aug Ⅱ作用30min后,心肌细胞PKC和TPK活性明显增加。Que(1-100μmol/L)能剂量依赖性地抑制Ang Ⅱ所致心肌细胞总蛋白含量、[~(14)C]尿苷和[~3H]酪氨酸掺入量、PKC及TPK活性的增加。结论:Que可抑制Aug Ⅱ致培养乳鼠心肌细胞肥大,该作用与抑制PKC及TPK活性有关。     

吡格列酮对培养的心肌细胞肥大的抑制作用

目的利用体外培养的乳鼠心肌细胞,观察吡格列酮对高浓度葡萄糖与去甲肾上腺素共同诱导的肥大心肌细胞的影响,进一步推测吡格列酮对糖尿病性心肌肥大的可能作用及作用机制。方法以培养的乳鼠心肌细胞为模型分组给药后,用显微镜目镜计数心肌细胞搏动的频率;用Lowry’s法测心肌细胞的蛋白质含量;用[3H]leucine标记法测定心肌细胞蛋白的合成;利用计算机图象分析系统测心肌细胞的体积。结果吡格列酮在1～10μmol·L-1浓度对25.5mmol·L-1高糖与1μmol·L-1去甲肾上腺素联合诱导的肥大心肌细胞的蛋白含量、蛋白合成及体积均有显著的抑制作用。其抑制肥大的效果比1μmol·L-1维拉帕米更为显著;同时观察到10μmol·L-1吡格列酮同1μmol·L-1维拉帕米一样有抑制心肌细胞搏动的作用。结论吡格列酮能有效抑制高糖与去甲肾上腺素联合诱导的心肌细胞肥大。这种作用可能是通过作用于PPARγ来实现的。     

海胆黄多糖SEP抑制高糖高胰岛素诱导的大鼠乳鼠心肌细胞肥大

目的观察海胆黄多糖SEP对高糖高胰岛素诱导的肥大心肌细胞的影响,并初步探索其作用机制。方法利用高糖高胰岛素模拟糖尿病机体微环境诱导乳鼠心肌细胞肥大模型,选择不同剂量海胆黄多糖SEP分组给药处理后,采用Lowrys法检测心肌细胞蛋白质含量;利用计算机图像分析系统检测心肌细胞表面积变化;采用RT-PCR法检测给药前后心肌细胞ANF和PPAR-αm RNA表达变化。结果与正常对照组相比,高糖高胰岛素组蛋白含量、细胞表面积、ANF和PPAR-αm RNA表达均明显增加;与高糖高胰岛素组相比,低、中、高给药组剂量依赖性降低了高糖高胰岛素诱导的肥大心肌细胞的蛋白含量、细胞表面积、以及ANF和PPAR-αm RNA表达。结论 SEP对高糖高胰岛素诱导的乳鼠心肌细胞肥大具有一定的抑制作用,PPAR-α信号通路可能参与了这一过程。     

Taurine attenuates hypertrophy induced by angiotensin II in cultured neonatal rat cardiac myocytes

The effect of taurine on angiotensin II-induced changes in cell morphology and biochemistry of the cultured neonatal cardiomyocyte was examined. Angiotensin II (1-100 nM) alone caused a slow increase in the surface area of the myocyte accompanied by an induction of the expression of atrial natriuretic peptide (ANP) and an upregulation of transforming growth factor beta(1) gene (TGF-beta(1)). The signaling pathway of angiotensin II (1-100 nM) was found to proceed through protein kinase C and the rapid activation of mitogen-activated protein (MAP) kinases. Pretreatment of the myocyte with taurine (20 mM) in the absence of angiotensin II had no visible effect on cell size or growth rate. However, the cells that were pretreated with taurine (20 mM) for 24 h exhibited reduced responsiveness to angiotensin II (100 nM) relative to surface cell area enlargement and the upregulation of the late and growth factor genes(ANP, TGF-beta(1)). Angiotensin II-mediated activation of the MAP kinases (extracellular signal-regulated protein kinase 1/2: ERK1/2) was not blocked by taurine. Taurine reduced the phosphorylation of a 29-kDa protein, a reaction which was enhanced by angiotensin II and appears to involve protein kinase C step. The results indicate that taurine is an effective inhibitor of certain aspects of angiotensin II action.     

Adenovirus-mediated FKBP12.6 overexpression induces hypertrophy and apoptosis in cultured neonatal cardiomyocytes

1. Cardiac ryanodine RyR2 receptors regulate Ca(2+) release from the sarcoplasmic reticulum (SR). FK506 binding protein (FKBP) 12.6 prevents aberrant SR Ca(2+) leakage during diastole, thereby maintaining the integrity of RyR2 function. Previous studies have focused mainly on FKBP12.6 deficiency and so the pathophysiological consequences of FKBP12.6 overexpression remain unclear. Herein, we investigate the effect of FKBP12.6 overexpression on cardiac hypertrophic and apoptotic signalling. 2. Human FKBP12.6 cDNA was cloned into pAdTrack-CMV and the resulting plasmid, along with a control empty plasmid, were transfected into bacteria. The resulting virus, namely Ad-FKBP12.6 containing green fluorescent protein, was propagated and purified. Neonatal rat cardiomyocytes were infected with this virus. Protein and DNA synthesis were measured by [(3)H]-leucine and [(3)H]-thymidine incorporation, respectively. Expression of p38 mitogen-activated protein kinase (MAPK), phosphorylated extracellular signal-regulated kinase 1 or 2 (p-ERK1/2) and Bax were examined by western blotting. 3. Compared with control cells, cardiomyocytes that overexpressed FKBP12.6 became hypertrophic and hyperplastic, with increased levels of both p38 MAPK and p-ERK1/2. At the same time, overexpression of FKBP12.6 induced apoptosis of cardiomyocytes, as determined by both Bax protein expression and DNA fragmentation. Rapamycin treatment downregulated the expression of p-ERK1/2, p38 MAPK and Bax in stimulated cardiomyocytes, with or without FKBP12.6 overexpression, and enhanced protein synthesis, but had no effect on DNA synthesis in cardiomyocytes. 4. In conclusion, FKBP12.6 overexpression may participate in pathophysiological processes through both hypertrophic and apoptotic signalling pathways, leading to cardiomyocyte damage and death.     

辛伐他汀对内皮素-1诱导氧活性物质介导心肌细胞肥大的抑制作用

目的　探讨辛伐他汀对内皮素 1 (endothelin 1 ,ET 1 )诱导的氧活性物质 (reactiveoxygenspecies,ROS)产生和心肌细胞肥大的抑制作用。方法　用原代培养的新生大鼠心肌细胞进行实验。细胞内荧光信号用荧光倒置显微镜检测。细胞内ROS水平用ROS敏感的荧光探针 2 ,7 dichlorofluo rescindictate(DCF DA)来反应 ,细胞内RNA含量用RNA敏感的荧光探针碘化丙啶 (propidiumiodide ,PI)来测定。用考马斯亮蓝法测定细胞内总蛋白含量。用图像分析软件 (Leica图像分析软件 )测细胞表面积。结果　①ET 1浓度依赖性地使心肌细胞内DCF DA的荧光信号增加和心肌细胞肥大。过氧化氢酶 (catalase ,CAT ,0 2U·L- 1 )抑制ET 1 (1× 1 0 - 8mol·L- 1 )诱导的心肌细胞内DCF DA的荧光信号的增加和心肌细胞肥大。②辛伐他汀对ET 1诱导的心肌细胞内DCF DA的荧光信号增强和心肌细胞肥大产生剂量依赖性的抑制作用。结论　ET 1能够使心肌细胞产生ROS和ROS依赖的心肌细胞肥大 ,辛伐他汀能抑制ET 1诱导的ROS依赖的心肌细胞肥大。     

Minoxidil attenuates ischemia-induced apoptosis in cultured neonatal rat cardiomyocytes

The effects of minoxidil (a mitochondrial K+(ATP) channel opener) on ischemia-induced necrosis and apoptosis were examined using a cardiomyocyte model of simulated ischemia, since mitochondrial K+(ATP) channel openers have been suggested to be involved in the mechanisms of cardioprotective action against ischemia/reperfusion injury. In the absence of minoxidil, simulated ischemia led to cellular release of creatine phosphokinase (CPK), morphologic degeneration, and beating cessation within 24 to 72 hours. Based on the Hoechst 33258 staining pattern, a significant number of cells placed in sealed flasks underwent apoptosis. Myocytes treated with 5 microM of minoxidil failed to alter the degree of ischemia-induced CPK loss for 48 to 72 hours. However, minoxidil treatment prevented the loss of beating function in many of the ischemic cells, and attenuated the decline in intracellular ATP content after a 48-hour ischemic incubation. The number of nuclear fragmentation was significantly reduced in minoxidil-treated cells after a 72-hour ischemic insult compared with untreated ischemic cells. This effect was blocked by the mitochondrial K+(ATP) channel antagonist 5-HD. The data suggest that minoxidil renders the cell resistant to ischemia-induced necrosis and apoptosis. The beneficial effects of minoxidil appear to be related to the opening of mitochondrial K+(ATP) channels.     

Dopamine D2 receptor stimulation inhibits angiotensin II-induced hypertrophy in cultured neonatal rat ventricular myocytes

1. Myocardial hypertrophy is a common pathological change that accompanies cardiovascular disease. Dopamine D2 receptors have been demonstrated in cardiovascular tissues. However, the pathophysiological involvement of D2 receptors in myocardial hypertrophy is unclear. Therefore, the effects of the D2 receptor agonist bromocriptine and the D2 receptor antagonist haloperidol on angiotensin (Ang) II- or endothelin (ET)-1-induced hypertrophy of cultured neonatal rat ventricular myocytes were investigated in the present study. 2. Protein content and protein synthesis, determined by examining [(3)H]-leucine uptake, were used as estimates of cardiomyocyte hypertrophy. The expression of D2 receptor protein in neonatal rat ventricular myocytes was determined using western blotting. Changes in [Ca(2+)](i) in cardiomyocytes were observed by laser scanning confocal microscopy. 3. Angiotensin II and ET-1, both at 10 nmol/L, induced myocyte hypertrophy, as demonstrated by increased protein content and synthesis, [Ca(2+)](i) levels, protein kinase C (PKC) activity and phosphorylation of extracellular signal-regulated kinase, c-Jun N-terminal kinase and mitogen-activated protein kinase (MAPK) p38 (p38). Concomitant treatment of cells with 10 nmol/L AngII plus 10 micromol/L bromocriptine significantly inhibited cardiomyocyte hypertrophy, MAPK phosphorylation and PKC activity in the membrane, as well as [Ca(2+)](i) signalling pathways, compared with the effects of AngII alone. In addition, 10 micromol/L bromocriptine significantly inhibited cardiomyocyte hypertrophy induced by 10 nmol/L ET-1. However, pretreatment with haloperidol (10 micromol/L) had no significant effects on cardiomyocyte hypertrophy induced by either AngII or ET-1. 4. In conclusion, D2 receptor stimulation inhibits AngII-induced hypertrophy of cultured neonatal rat ventricular myocytes via inhibition of MAPK, PKC and [Ca(2+)](i) signalling pathways.     

HSP70 and GRP78 induced by endothelin-1 pretreatment enhance tolerance to hypoxia in cultured neonatal rat cardiomyocytes

The heat shock protein 70 and glucose-regulated protein 78 have been shown to protect cells against deleterious stimuli. This study was performed to determine whether endothelin-1 pretreatment could increase cardiomyocyte tolerance to hypoxia and induce heat shock protein 70 and glucose-regulated protein 78 expression. Cultured cardiomyocytes were treated with endothelin-1 at doses of 0.01, 0.1 and 1.0 nmol/L for 10 minutes followed by 10 minutes endothelin-1-free normal medium prior to 12 hours hypoxia. Lactate dehydrogenase activity and malondialdehyde level in the medium were determined at the end of hypoxia, and myocyte heat shock protein 70 and glucose-regulated protein 78 were assayed with Western blot. Lactate dehydrogenase activity and malondialdehyde content in the medium were significantly elevated after hypoxia (P < 0.01, n = 6). Heat shock protein 70 and glucoseregulated protein 78 expression in cardiomyocytes also increased significantly after hypoxia (P < 0.01 vs control, n = 3). Endothelin- 1 pretreatment reduced lactate dehydrogenase and malondialdehyde after hypoxia, and increased heat shock protein 70 and glucoseregulated protein 78 levels during normal culture and hypoxia. Glucose-regulated protein 78 antisense oligodeoxynucleotide partially abrogated the protective effect of endothelin-1 pretreatment on hypoxic cardiomyocyte injury. This study indicated that endothelin-1 pretreatment could protect hypoxic cardiomyocytes and might exert this effect through upregulation of heat shock protein 70 and glucose-regulated protein 78.     

Enhancement of nitric oxide production by methylecgonidine in cultured neonatal rat cardiomyocytes.

1. In the present experiments, we investigated the effects of methylecgonidine (MEG) on nitric oxide (NO) production in cultured neonatal rat cardiomyocytes. Incubation of cultured cardiomyocytes with carbachol or MEG for 48 h significantly enhanced NO production. No release was increased from 1.48+/-0.13 microM (mg protein)(-1) for control to 5.73+/-0.19 microM (mg protein)(-1) for 1 microM carbachol treated cells (P<0.001). In addition, incubation with 1 microM MEG enhanced NO production to 5.55+/-0.28 microM (mg protein)(-1). The effects of MEG on NO production were concentration-dependent. The muscarinic antagonist atropine prevented the enhancement of NO production induced by carbachol or MEG. Compared to MEG-induced NO production, cocaine was much less potent. 2. The enhancement of NO production by carbachol or MEG was even greater in cultured cardiomyocytes transfected with the M(2) cDNA. After 48-h incubation with 1 microM carbachol or 1 microM MEG, NO production was increased by 6.5 and 6.7 fold, respectively, in cardiomyocytes overexpressing M(2) receptors. Coincubation with atropine or N(G)-nitro-L-arginine methyl ester abolished the enhancement of NO production. In contrast, NO production enhanced by carbachol or MEG in M(1)- or M(3)-transfected cardiomyocytes was similar to the level in non-transfected cells. 3. Western blot analysis showed that the protein levels of M(1), M(2), and M(3) were significantly increased in cardiomyocytes transfected with the receptor cDNAs, but MEG had no effect on the expressions. It is interesting that both carbachol and MEG caused a significant increase in constitutive endothelial NO synthase (eNOS) only in M(2)-transfected cardiomyocytes, not in non-transfected, M(1)- or M(3)-transfected cells. Again, atropine blocked the MEG-produced induction of eNOS. 4. Our data demonstrate that MEG significantly enhanced NO production in cultured cardiomyocytes and that the enhancement of NO production may result from MEG stimulation of muscarinic M(2) receptors.     

L-精氨酸-NO途径抑制血管紧张素Ⅱ诱导的心肌细胞肥大反应

目的探讨L-精氨酸(L-arginine,L-Arg)对心肌细胞血管紧张素Ⅱ受体(angiotensin Ⅱ receptor,ATR)及丝裂原活化蛋白激酶(mitogen-activated protein kinase,MAPK)表达的影响,进而阐述L-Arg对病理性心肌肥大的影响作用及相关机制。方法用血管紧张素Ⅱ(angiotensinⅡ,ATⅡ)、ATR抑制剂、L-Arg和(或)L-NAME(L-硝基精氨酸甲酯)分别作用于心肌细胞,然后以[3H]-亮氨酸参入法检测细胞蛋白合成速率、比色法检测一氧化氮(NO)生成量、RT-PCR及Western blot检测ATR及p38MAPK的表达水平。结果①给予L-Arg可缓解ATⅡ引起的心肌细胞NO合成量下降,减弱血管紧张素Ⅱ-1型受体(angiotensin receptor type1,ATR1)表达及下调p38MAPK蛋白磷酸化水平,并降低心肌细胞蛋白合成速率给予ATⅡ或L-Arg均未影响血管紧张素Ⅱ-2受体(angiotensin receptor type 2,ATP2)的表达水平;②心肌ATR1表达水平及p38MAPK蛋白磷酸化水平均与NO合成量之间存在线性负相关。多元逐步回归分析显示在ATR1与ATR2中,仅ATR1的表达水平与p38MAPK蛋白磷酸化水平之间存在回归关系。结论①L-Arg可致心肌细胞NO合成量增加,后者可抑制ATR1介导的p38MAPK蛋白磷酸化水平上调,进而抑制心肌细胞肥大反应;②ATR2未参与上述过程。     

Molecular mechanism of the inhibitory effect of trilinolein on endothelin-1-induced hypertrophy of cultured neonatal rat cardiomyocytes

Trilinolein, isolated from the traditional Chinese herb Sanchi ( Panax notoginseng), has been shown to have myocardial protective effects via its antioxidant ability. However, the cellular and molecular mechanisms of the protective effect of trilinolein in the heart remain to be elucidated. Oxidative mechanisms have been implicated in neonatal cardiomyocyte hypertrophy. We therefore have examined whether trilinolein attenuates reactive oxygen species (ROS) production and thus ET-1-induced hypertrophy of cardiomyocytes. Cultured neonatal rat cardiomyocytes were stimulated with ET-1 (10 nM), [3H]leucine incorporation and the beta-myosin heavy chain (beta-MyHC) promoter activity were examined. Trilinolein (1 and 10 microM) inhibited the ET-1-induced increase of [3H]-leucine incorporation in a concentration-dependent manner. Trilinolein (1 and 10 microM) also inhibited ET-1-induced beta-MyHC promoter activity in cardiomyocytes. We further examined the effects of trilinolein on ET-1-induced intracellular ROS generation by measuring a redox-sensitive fluorescent dye, 2',7'-dichlorofluorescin diacetate, fluorescence intensity. Trilinolein (1 and 10 microM) inhibited ET-1-increased intracellular ROS levels in a concentration-dependent manner. This increase of ROS by ET-1 (10 nM) or H2O2 (25 microM) was significantly inhibited by trilinolein (10 microM) and N-acetylcysteine (10 mM). Moreover, ET-1- or H2O2-induced beta-MyHC promoter activity and protein synthesis were also inhibited by trilinolein (10 microM). These data indicate that trilinolein inhibits ET-1-induced beta-MyHC promoter activity, and subsequent hypertrophy via its antioxidant ability in cardiomyocytes.     

尿促皮素诱导乳大鼠心肌细胞肥大的作用及信号传导机制

目的探讨尿促皮素(urocortin)诱导大鼠心肌细胞肥大的作用及其信号传导机制。方法实验分8组,正常对照组、尿促皮素0.1μmol.L-1组、星形孢菌素(Sta)1μmo.lL-1、H890.1μmol.L-1和维拉帕米(Ver)1μmol.L-1组及尿促皮素分别加Sta,H89和Ver组。采用体外培养的乳大鼠心肌细胞,应用尿促皮素0.1μmol.L-1诱导心肌肥大,观察Sta1μmol.L-1,H890.1μmo.lL-1和Ver1μmol.L-1的作用,进一步探讨尿促皮素0.1μmol.L-1诱导心肌肥厚的作用机制。用消化分离法及计算机图像分析系统检测心肌细胞直径;[3H]亮氨酸掺入法测定心肌细胞蛋白质的合成;用Lowry法检测心肌细胞蛋白质含量;用Western蛋白印迹法测定心房钠尿肽(ANP)表达;采用Till阳离子测定系统,以Fura-2/AM为荧光探针,观察心肌细胞[Ca2+]i瞬间变化。结果尿促皮素使心肌细胞直径、蛋白质合成、蛋白质含量和ANP表达分别增加30.9%,36.3%,35.5%和34.7%;尿促皮素+Sta组使心肌细胞直径、蛋白质合成、蛋白质含量和ANP表达分别降低了16.5%,22.1%,18.1%和21.3%;尿促皮素+H89组使心肌细胞直径、蛋白质合成、蛋白质含量和ANP表达分别降低了16.6%,21.5%,19.5%和20.6%;尿促皮素+Ver组使心肌细胞直径、蛋白质合成、蛋白质含量和ANP表达分别降低了17.1%,20.9%,17.9%及19.9%;尿促皮素能够使心肌细胞[Ca2+]i瞬间变化水平增高,Sta,H89和Ver能够降低尿促皮素引起的心肌细胞[Ca2+]i瞬间变化升高。结论尿促皮素可能通过蛋白激酶C和蛋白激酶A信号途径影响L-型Ca2+通道,进而影响细胞[Ca2+]i瞬间变化水平,诱导乳大鼠心肌细胞肥大。     

Resveratrol prevents norepinephrine induced hypertrophy in adult rat cardiomyocytes, by activating NO-AMPK pathway

Increased adrenergic drive is a major factor influencing the development of pathological cardiac hypertrophy, a stage which precedes overt heart failure. We examined the effect of resveratrol, a polyphenol (found predominantly in grapes), in preventing norepinephrine induced hypertrophy of adult cardiomyocyte, and the role of nitric oxide (NO) and adenosine monophosphate kinase (AMPK) in the effects of resveratrol. Cardiomyocytes isolated from adult rats were pretreated, or not, with resveratrol and then exposed to norepinephrine for 24h. In other experiments cardiomyocytes were also treated with different pharmacological inhibitors of NO synthase, AMPK and sirtuin for elucidating the signaling pathways underlying the effect of resveratrol. In order to validate the role of these signaling molecules in the in vivo settings, we also examined hearts from resveratrol treated spontaneously hypertensive rats (SHR), a genetic model of essential hypertension. Cardiomyocyte hypertrophy was determined by morphometry and (3)H-phenylalanine incorporation assay. NO levels and AMPK activity were measured using a specific assay kit and western blot analysis respectively. In vitro, resveratrol prevented the norepinephrine-induced increase in cardiomyocytes size and protein synthesis. Pharmacological inhibition of NO-AMPK signaling abolished the anti-hypertrophic action of resveratrol. Consistent with the in vitro findings, the anti-hypertrophic effect of resveratrol in the SHR model was associated with increases in NO and AMPK activity. This study demonstrates that NO-AMPK signaling is linked to the anti-hypertrophic effect of resveratrol in adult cardiomyocytes in vitro, and in the SHR model in vivo.     

二十碳五烯酸对高糖与去甲肾上腺素诱导的心肌细胞肥大的抑制作用

糖尿病性心肌肥大是糖尿病的严重并发症之一,如何改善糖尿病性左室肥大已经成为目前治疗糖尿病的重点研究课题.二十碳五烯酸(eicosapentaenoic acid,EPA)是人体必需脂肪酸之一,属于Ω-3系列多不饱和脂肪酸,其对高血压、心肌梗死等疾病的预防与治疗具有较好的效果[1],最新研究显示[2],EPA能够参与抑制转化生长因子β1(TGF-β1)和c-jun氨基末端激酶(JNK)等因子来产生抑制心肌细胞肥大的作用,那么是否EPA在糖尿病心肌病所产生的心肌细胞肥大也有同样的抑制作用,目前还未见国内外有相关报道.     

匹格列酮抑制小鼠肝切除术后肝脏再生

目的:探讨匹格列酮在小鼠肝切除术后肝脏再生中的作用。方法:对C57BL/6J小鼠实施2/3肝切除,建立小鼠肝再生模型。实验组小鼠按体重给予匹格列酮20mg.kg-1.d-1口服,对照组给予安慰剂口服,在术后不同时间点收集小鼠残余肝脏和血清,计算肝脏体重比;监测术后肝功能和血糖变化;H&E染色观察肝脏形态学变化,免疫组化染色观察肝细胞增殖情况。结果:匹格列酮20mg.kg-1.d-1对小鼠术后肝功能和血糖无明显影响。与对照组相比,匹格列酮组小鼠术后肝脏生长缓慢,肝细胞增殖受到抑制(P<0.05)。结论:匹格列酮抑制小鼠肝切除术后肝脏再生。