Toxicity of ecstasy (MDMA) towards embryonic stem cell-derived cardiac and neural cells

“Ecstasy” or methylenedioxymethamphetamine (MDMA) is primarily a recreational drug commonly used during the child bearing period, thus, there is a major concern regarding the embryonic and fetal toxicity of this drug. Here, we report the cardio- and neuro-toxic effects of MDMA on beating embryoid bodies (EBs) and neural cell-containing EBs derived from mouse embryonic stem cell (ESCs). Based on our linear discriminate function, MDMA is considered to be a moderate or weak teratogen. Moreover, the generation of EBs with neural cell morphology and the expression of MAP2, a mature neuron marker, decrease more when MDMA is administered during the EB formation stage rather than post-plated EBs. In addition, the ID50 (inhibition of differentiation) of EBs with neural cell morphology is less than cardiac cells. In conclusion, MDMA causes a marked reduction in beating cardiomyocytes and neurons in ESC cultures, and this drug has a more potent toxicity on neural rather than cardiac cell differentiation.     

参附注射液对心肌细胞缺氧及缺氧/复氧时Fas/FasL表达的影响

目的 探讨参附注射液（SF）对培养的乳鼠心肌细胞缺氧及缺氧／复氧时凋亡相关基因Fas／FasL蛋白表达的影响。方法 按常规培养新生4d乳鼠心肌细胞，于培养24h后进行缺氧及缺氧／复氧实验。以免疫组织化学方法检测心肌细胞Fas／FasL蛋白表达的变化。结果 缺氧4．5h及10．5h后，心肌细胞Fas／FasL蛋白的阳性表达指数（positive expression index，PEI）均显著高于对照。10．5h组与4．5h组无明显差异。参附注射液组PEI明显低于缺氧组（P〈0．05）。缺氧30min后再给氧4h与10h，心肌细胞Fas／FasL蛋白的PEI显著高于对照，复氧10h组与4h组无明显差异，参附注射液组PEI低于无SF组（P〈0．05）。结论 缺氧及缺氧／复氧时均有凋亡相关基因Fas及其配体FasL蛋白表达的增强，参附注射液可通过下调Fas／FasL蛋白表达，减少凋亡从而减轻缺氧损伤及缺氧／复氧损伤。     

Nitric oxide induces caspase-dependent apoptosis and necrosis in neonatal rat cardiomyocytes

Excessive nitric oxide (NO) production has been implicated in the pathophysiology of cardiomyocyte (CMC) apoptosis and necrosis induced by ischemia/reperfusion, inflammation and NO-donating chemicals. Although caspases are known to be involved in apoptosis, the present study examined whether caspases also play a role in NO-induced CMC necrosis. Neonatal rat CMCs were labeled with Annexin-V and propidium iodide, and apoptosis and necrosis were analyzed by confocal images and fluorescence activated cell sorter analysis. CMC apoptosis and necrosis were also evaluated by determining DNA fragmentation in the cell and the supernatant fractions. Treatment of CMCs with the NO donor, diethylenetriamine NO (DETA/NO) or S-nitroso-N-acetyl-penicillamine (SNAP) at concentrations of 10 and 100 microM for 24h induced predominantly apoptosis over necrosis, but a higher concentration (1mM) of DETA/NO or SNAP provoked both apoptosis and necrosis. The lower doses of DETA/NO-induced apoptosis was associated with a gradual increase in caspase-3 activity over 24h without appreciable activation of poly ADP-ribose polymerase (PARP), while the higher dose of DETA/NO induced a marked increase in caspase-3 activity and CMC apoptosis until 2h after the treatment, and increased necrotic CMCs thereafter associated with robust activation of PARP. The caspase inhibitor Z-DEVD-FMK but not the poly ADP-ribose polymerase (PARP) inhibitor 3-aminobenzamide (3-AB) abolished caspase-3 activation and CMC apoptosis induced by 100 microM DETA/NO. However, both Z-DEVD-FMK and 3-AB abolished PARP activation and CMC necrosis induced by 1mM DETA/NO. The amount of nicotinamide adenine dinucleotide (NAD) and adenine nucleotides in CMCs was not significantly affected by treatment with 10 and 100 microM DETA/NO, but was significantly reduced by treatment with 1mM DETA/NO without a decline of adenylate energy charge. The depletion of NAD and adenine nucleotides was abrogated by Z-DEVD-FMK and 3-AB. These results suggest that caspase activation play a crucial role in CMC apoptosis induced by lower concentrations of NO as well as in CMC necrosis induced by a higher concentration of and a longer exposure to NO. NO-induced CMC necrosis is likely mediated by PARP activation which occurs as a consequence of caspase activation.     

Molecular determinants of the physiological adaptation to stress in the cardiomyocyte: a focus on AKT

Cardiomyocytes (CMCs) adapt to physiological or pathological stimuli by undergoing molecular changes which differentiate according to the specificity of the stimulus and eventually generate a phenotype with peculiar molecular characteristics. Here, we review the literature on the molecular mechanisms activated in the CMC during physiologic adaptation to stress, as opposed to maladaptation. The critical role of the IGF-1 receptor/PI3K/Akt signaling pathway during this process is described, including effector targets regulating inotropism and cell size.     

鞘磷脂酶在柯萨奇病毒B3感染心肌细胞中的作用

目的检测柯萨奇病毒B3(CVB3)感染心肌细胞后鞘磷脂酶活性的变化、鞘磷脂酶mRNA、CVB3RNA的表达、病毒滴度的变化及心肌细胞表型的变化。初步探讨鞘磷脂酶在CVB3感染的心肌细胞中的作用。方法 CVB3感染心肌细胞后不同时间点,用薄层色谱法(TLC)检测鞘磷脂酶活性;用Real time-PCR检测心肌细胞中鞘磷脂酶mRNA与CVB3RNA的表达;同时取细胞培养上清液检测CVB3滴度。用Annexin V-FITC,PI双染法观察心肌细胞表型变化。设正常心肌细胞对照组,每个时间点设三个复孔。结果病毒感染组与正常心肌细胞相比,酸性鞘磷脂酶在4h、12h时活性有升高,其mRNA表达在2h时有升高趋势(P0.05);中性Mg2+非依赖性鞘磷脂酶活性在4h时有明显升高,在12h时活性下降,而其mRNA表达在20h时升高(P0.05);中性Mg2+依赖性鞘磷脂酶活性于病毒感染后4h、12h无明显变化,其mRNA表达在各组间也无明显变化。心肌细胞内病毒RNA表达在4h时有升高趋势,8h后开始明显升高(P0.01)。CVB3病毒滴度在2h时明显升高(P0.05)。心肌细胞在病毒感染2h后早期凋亡及坏死开始增加,4h时凋亡坏死增加更明显,到24h时坏死心肌细胞明显增多。以上实验均重复3次。结论中性Mg2+非依赖性鞘磷脂酶与酸性鞘磷脂酶在CVB3侵入心肌细胞及病毒的扩散增殖过程中可能起重要作用;而中性Mg2+依赖性鞘磷脂酶在此过程中可能不起作用。     

血管内皮生长因子165通过抑制钙敏感性受体减少缺血/再灌注心肌细胞凋亡

目的:探讨血管内皮生长因子165(vascu-lar endothelial growth factor 165,VEGF165)在缺血/再灌注损伤中的抗细胞凋亡作用及与钙敏感性受体(calciumsensing receptor,CaSR)表达下调的关系。方法:新生鼠心肌细胞在模拟心肌缺血状态下孵育2 h,然后在标准培养液中再培养24 h,从而建立一个模拟心肌缺血/再灌注模型。通过末端脱氧核苷酰基转移酶介导性dUTP切口末端标记(TUNEL法)检测心肌细胞凋亡。CaSR mRNA表达通过逆转录聚合酶链反应(RT-PCR)测定。通过免疫印迹法(Westernblot)测定促凋亡蛋白Bax、抗凋亡蛋白Bcl-2含量。结果:模拟的缺血/再灌注后CaSR mRNA的表达(I/R组:2.6±0.4;对照组:1.0±0.3,P<0.01)和TUNEL阳性细胞增加(I/R组:15.3%±2.5%;对照组:2.9%±1.4%,P<0.01)。GdCl3、CaSR mRNA的表达(GdCl3组:4.5±0.6;I/R组:2.6±0.4,P<0.01)及TUNEL阳性细胞进一步增加(GdCl3组:25.4%±2.6%;I/R组:15.3%±2.5%,P<0.01),同时上调了Bax表达(GdCl3组:1.93±0.28;I/R组:1.50±0.21,P<0.01),下调了Bcl-2的表达(GdCl3组:0.82±0.18;I/R组:1.71±0.30,P<0.01)。VEGF165组Bax表达减少(GdCl3+VEGF165组:1.12±0.23;GdCl3组:1.93±0.28,P<0.05)和Bcl-2的表达增加(GdCl3+VEGF165组:2.56±0.54;GdCl3组:0.82±0.18,P<0.05),TUNEL阳性细胞减少(GdCl3+VEGF165组:11.8%±1.9%;GdCl3组:25.4%±2.6%,P<0.05),CaSR mRNA的表达下调(GdCl3+VEGF165组:1.5±0.4;GdCl3组:4.5±0.6,P<0.01)。结论:VEGF165通过抑制CaSR,促进Bcl-2和抑制Bax的表达来减少缺血/再灌注诱导的心肌细胞凋亡。     

蕨麻多糖抗缺氧作用研究

【目的】研究蕨麻多糖抗缺氧作用。【方法】取新生SD乳鼠心肌细胞,建立缺氧损伤模型,设正常对照组、缺氧损伤模型组、香丹注射液阳性对照组（2mg/ml）、蕨麻多糖高、中、低浓度组,浓度分别为0.2、0.02、0.002mg/ml。正常对照组在DMEM/F-12培养基中37℃培养于含5%CO2培养箱中,其它各组在D-Hanks液中37℃在混合气体培养箱中（95%N2、5%CO2、O2浓度〈1%）。培养6h后,采用四甲基偶氮唑盐法检测心肌细胞代谢活力;采用比色法检测细胞外乳酸脱氢酶活性。采用小鼠常压窒息性缺氧模型,观察缺氧状态下各组小鼠的存活时间。【结果】与缺氧模型组比较,蕨麻多糖0.2mg/ml、0.02mg/ml剂量组均使细胞代谢率显著升高（P〈0.05）。与正常对照组比较,给予小鼠蕨麻多糖1.8g/kg可使其平均存活时间延长28.91%（P〈0.01）。【结论】蕨麻多糖具有抗缺氧作用,并与剂量有关。     

NADPH氧化酶源性ROS在乳鼠心肌细胞肥大中的作用

目的探讨NADPH氧化酶来源的活性氧(ROS)在TNF-α诱导乳鼠心肌细胞肥大中的作用。方法采用体外乳鼠心肌细胞培养,给予TNF-α、APO单独或联合作用细胞24h,以BCA法测定心肌细胞蛋白合成,共聚焦显微镜测量心肌细胞ROS含量,RT-PCR法测定心肌细胞心钠素ANP mRNA的表达。结果 TNF-α可明显增加心肌细胞蛋白合成,心肌细胞体积增大,ROS生成增多,ANP mRNA表达水平显著增加,以上作用可被APO明显抑制。结论TNF-α通过增加心肌细胞NADPH氧化酶来源的ROS生成,促进心肌细胞肥大。     

Can the cardiomyocyte cell cycle be reprogrammed?

Cardiac repair following myocardial injury is restricted due to the limited proliferative potential of adult cardiomyocytes. The ability of mammalian cardiomyocytes to proliferate is lost shortly after birth as cardiomyocytes withdraw from the cell cycle and differentiate. We do not fully understand the molecular and cellular mechanisms that regulate this cell cycle withdrawal, although if we could it might lead to the discovery of novel therapeutic targets for improving cardiac repair following myocardial injury. For the last decade, researchers have investigated cardiomyocyte cell cycle control, commonly using transgenic mouse models or recombinant adenoviruses to manipulate cell cycle regulators in vivo or in vitro. This review discusses cardiomyocyte cell cycle regulation and summarises recent data from studies manipulating the expressions and activities of cell cycle regulators in cardiomyocytes. The validity of therapeutic strategies that aim to reinstate the proliferative potential of cardiomyocytes to improve myocardial repair following injury will be discussed.     

Lmcd1/Dyxin, a novel Z-disc associated LIM protein, mediates cardiac hypertrophy in vitro and in vivo

To identify new mediators of cardiac hypertrophy, we performed a genome-wide mRNA screen of stretched neonatal rat cardiomyocytes (NRCMs). In addition to known members of the hypertrophic gene program, we found the novel sarcomeric Z-disc LIM protein Lmcd1/Dyxin markedly upregulated. Consistently, Lmcd1 was also induced in several mouse models of myocardial hypertrophy suggesting a causal role in cardiac hypertrophy. We overexpressed Lmcd1 in NRCM, which led to cardiomyocyte hypertrophy and induction of the hypertrophic gene program. Likewise, the calcineurin-responsive gene RCAN1-4 was found significantly upregulated. Conversely, knockdown of Lmcd1 blunted the response to hypertrophic stimuli such as stretch and phenylephrine (PE), suggesting that Lmcd1 is required for the hypertrophic response. Furthermore, PE-mediated activation of calcineurin was completely blocked by knockdown of Lmcd1. To confirm these results in vivo, we generated transgenic mice with cardiac-restricted overexpression of Lmcd1. Despite normal cardiac function, adult transgenic mice displayed significant cardiac hypertrophy, again accompanied by induction of hypertrophic marker genes such as ANF and α-skeletal actin. Likewise, Rcan1-4 was found upregulated. Moreover, when crossed with transgenic mice overexpressing constitutionally active calcineurin, Lmcd1 transgenic mice revealed an exacerbated cardiomyopathic phenotype with depressed contractile function and further increased cardiomyocyte hypertrophy. We show that the novel z-disc protein Lmcd1/Dyxin is significantly upregulated in several models of cardiac hypertrophy. Lmcd1/Dyxin potently induces cardiomyocyte hypertrophy both in vitro and in vivo, while knockdown of this molecule prevents hypertrophy. Mechanistically, Lmcd1/Dyxin appears to signal through the calcineurin pathway. Lmcd1/Dyxin may thus represent an attractive target for novel antihypertrophic strategies.