参麦注射液对大鼠急性心肌缺血及eNOS mRNA表达的影响

目的：探讨参麦注射液(SMI)预处理可能对 大鼠急性心肌缺血及心肌内皮型一氧化氮合酶(eNOS)mRNA表达的影响。方法:大鼠随机分为对照组、模型组、处理组1和处理组2，应用异丙肾上腺素建立大鼠心肌 缺血模型,以心电图ST段抬高值作为心肌缺血指标，硝酸还原酶法测定血清和心肌的NO^-₂/NO^-₃，RT-PCR检测心肌eNOS mRNA表达。结果：模型组各时点的心 电图ST段均显著高于对照组，缺血20 min时达高峰，血清和心肌NO^-₂/NO^-₃含量及 心肌eNOS mRNA表达均低于对照组；两个处理组于缺血20、30、40 min时的心电图ST段抬高 幅度均显著低于模型组，血清和心肌NO^-₂/NO^-₃含量均显著高于模型组，心肌eNOS mRNA表达强于模型组；处理组1和处理组2比较，心电图ST段抬高幅度、血清和心肌的NO^-₂/NO^-₃含量及心肌eNOS mRNA表达差异均无显著。结论：参麦注 射液可能是通过促进心肌组织eNOS mRNA表达、增强eNOS活性而提高NO水平，达到抗心肌缺 血的作用。     

Morphologic alterations of cholinergic processes in the neocortex of aged rats

In the present study we observed enlarged cholinergic processes in the neocortex of aged Fischer 344 rats. These swollen ChAT-positive profiles appeared either as a single axon enlargement or, in many instances, the bulbous processes coalesced to form grape-like clusters of immunoreactivity. The latter structures looked similar to the immunoreactive profiles observed in the cortex of patients with Alzheimer's disease and in the rat septum following fimbria-fornix transection. Together, these data provide evidence that morphologic changes occur within processes of cholinergic neurons in the aged rat. Moreover, the similarity in appearance between the axonal alterations in the aged rat and in patients with Alzheimer's disease suggests a common pathologic process.     

厚朴酚减轻缺血大鼠心肌损伤

目的研究厚朴酚(Mag)对大鼠缺血心肌的保护作用及可能的机制。方法 SD大鼠分为对照组、模型组和厚朴酚组。模型组采用结扎大鼠左冠状动脉前降支建立急性心肌梗死模型。Mag组建模型前预先30 min给予高、中和低3种浓度的厚朴酚(40、20和10 mg/kg)。酶联免疫法检测血清超氧化物歧化酶(SOD)活力和丙二醛(MDA)含量,DNA断裂的原位末端标记法(TUNEL)检测心肌细胞凋亡,Western blot法检测Bcl-2、caspase-3和Bax蛋白表达,激光共聚焦技术检测[Ca2+]i。结果1)模型组LVEDP较对照组显著增加(P0.05),LVSP及±dp/dtmax较对照组显著降低(P0.05)。Mag组(40 mg/kg)LVEDP较模型组显著降低(P0.05),LVSP及±dp/dtmax较模型组显著增加(P0.05)。2)模型组Bcl-2表达较对照组显著降低(P0.05),30 mmol/L KCl诱导的[Ca2+]i、Bax及caspase-3表达较对照组显著升高(P0.05)。Mag组(40 mg/kg)Bcl-2表达水平较模型组显著增加(P0.05),30 mmol/L KCl诱导的[Ca2+]i、Bax及caspase-3表达较模型组显著降低(P0.05)。结论厚朴酚减轻大鼠缺血心肌损伤可能与下调[Ca2+]i和抑制心肌细胞凋亡有关。     

5-羟色胺对大鼠心肌单相动作电位及室性心律失常的影响

为探讨5-HT与缺血性室性心律失常的关系,观察了外源性5-HT对大鼠在体缺血心肌单相动作电位(MAP)及心电图的影响。结果证实(1)5-HT使心肌缺血动物DVA的VE数目增加,VT、VF持续时间延长,而不造成非心肌缺血动物的室性心律失常。(2)5-HT对缺血心脏DVA的影响不是通过MAPD的延长,而是与缺血心肌Vmax及MAPA有关。     

通心络对心肌梗死大鼠心室缝隙连接蛋白43重构及室性心律失常的影响

目的:探讨通心络(TXL)对心肌梗死大鼠心室缝隙连接蛋白43(Cx43)重构及室性心律失常(VA)的影响。方法:雄性SD大鼠100只,随机分为假手术(sham)组(n=25)和手术组(n=75)。手术组动物结扎冠状动脉左前降支制备心肌梗死模型,假手术组只开胸不结扎。将手术后存活3 d的大鼠随机分为TXL治疗组(TXL组)和心肌梗死组(MI组)。TXL组给予TXL(2 g·kg-1·d-1)连续4周灌胃治疗,MI组和sham组则给予等体积生理盐水灌胃。药物干预结束后,采用酶联免疫吸附法检测梗死周边区心肌组织白细胞介素-1β(IL-1β)及内皮素-1(ET-1)的水平;免疫组化法检测Cx43的分布;Western blotting法检测Cx43表达;RT-PCR法检测Cx43 mRNA的表达;采用Burst刺激诱发VA。结果:与sham组相比,MI组梗死周边心肌的IL-1β和ET-1水平均显著升高,而Cx43的mRNA及蛋白表达均显著降低,Cx43分布无规律性且侧面化分布增多,VA诱发率也明显升高(P0.05);与MI组相比,TXL组梗死周边心肌IL-1β和ET-1水平明显降低,Cx43的mRNA及蛋白表达均显著增加,Cx43部分呈线性分布于心肌细胞闰盘处,VA诱发率也明显降低(P0.05)。结论:TXL可降低心肌梗死大鼠VA的发生率,其机制可能与TXL抑制心肌梗死后Cx43重构有关。     

心肌梗死大鼠缺血心肌中内皮抑素的表达

目的： 观察心肌梗死后大鼠不同时间缺血心肌中内皮抑素的表达及其与新生血管密度和血管内皮生长因子（VEGF）的关系。 方法： 32只心肌梗死SD大鼠随机分为心肌梗死后7、14、21、28 d 4个组，以假手术组作为正常对照组，每组8只。应用免疫组织化学染色方法，观察各组心肌梗死大鼠缺血心肌中内皮抑素、VEGF 的表达和新生血管密度。 结果： 心肌梗死大鼠缺血心肌中内皮抑素的表达明显增加，弥散分部于心肌细胞和组织间隙，第7 d表达量最高，至14、21、28 d表达量逐渐降低，28 d基本降至基础水平，与VEGF表达的变化趋势一致，并与新生血管密度相关。 结论： 内皮抑素在心肌梗死大鼠的缺血心肌中表达增加，与VEGF的动态变化一致，并与新生血管密度呈正相关，提示内皮抑素可能参与缺血心肌血管新生的调节。     

Changes in ultrasonic attenuation indicative of early myocardial ischemic injury.

This study was designed to determine whether quantitative alterations in ultrasonic attenuation are associated with myocardial changes occurring after acute ischemic injury. Five hundred seventeen regions of myocardium from 41 dogs were studied in vitro at five intervals after coronary occlusion: 15 min, 1 h, 6 h, 24 h, 3 days, and 6 wk. Quantitative indices of ultrasonic attenuation were determined from the measured frequency dependence of the ultrasonic attenuation coefficient characterizing each myocardial region over the range 2-10 MHz. Independent definition of regions of ischemic injury was provided by either creatine kinase depletion or colloidal carbon dye distribution. Results of this study indicate that ischemic myocardial regions investigated 15 min to 24 h after coronary occlusion demonstrated ultrasonic attenuation significantly decreased from nonischemic regions (P less than 0.05). In contrast, ultrasonic attenuation was significantly increased in zones of ischemia or infarction investigated at 3 days and 6 wk after coronary occlusion (P less than 0.05 and P less than 0.01, respectively). These results indicate that altered attenuation of transmitted ultrasound by myocardium in vitro is an early manifestation of ischemia.     

Paradoxical sleep insomnia and decreased cholinergic neurons after myocardial infarction in rats

Study Objectives:

Acute myocardial infarction (MI) is followed, within a few hours, by neuronal loss in the central nervous system (CNS), including the limbic system, the hypothalamus, and the brainstem. Sleep before and after MI was investigated in the first experiment. In a parallel experiment, 2 weeks after MI, we quantified brainstem cholinergic neurons known to control paradoxical sleep (PS).

Measurements and Results:

Data were obtained from 28 adult male Sprague-Dawley rats weighing 350-375 g and maintained under a 12-12 light-dark cycle in 2 experiments on 16 and 12 rats, respectively. The 16 animals in the first experiment were implanted with chronic electroencephalographic (EEG) and electromyographic (EMG) electrodes. A week after surgery, these animals were habituated for 2 days to the recording equipment, and baseline sleep was charted for 24 h. The next morning, MI was induced in 8 rats by occluding the left anterior descending coronary artery for 40 min. The remaining 8 rats served as sham-operated controls. Sleep was recorded again 2 weeks after MI. The number of choline acetyltransferase (ChAT)-positive neurons was counted in the second, parallel experiment on 6 MI and 6 sham rats.Compared to the sham controls, MI rats displayed longer latency to sleep onset, shorter latency to paradoxical sleep (PS), and curtailed PS duration. The number of ChAT-positive neurons in the pedunculopontine tegmentum (PPT) area of MI rats was significantly decreased compared to the sham controls, while the number of laterodorsal tegmentum (LDT) cholinergic neurons was not different.

Conclusion:

Acute MI is accompanied, within 2 weeks, by PS-specific insomnia that can be explained, at least partly, by a specific loss of cholinergic neurons in an area known to control PS.

Citation:

Bah TM; Laplante F; Wann BP; Sullivan R; Rousseau G; Godbout R. Paradoxical sleep insomnia and decreased cholinergic neurons after myocardial infarction in rats. SLEEP 2010;33(12):1703-1710.     

缺血预处理抗缺血再灌注心肌间质损伤的实验研究

目的：观察缺血预处理（ＩＰＣ） 对大鼠缺血再灌注心肌间质胶原及心肌功能结构关系的影响,以进一步探讨ＩＰＣ 对心肌的保护作用。方法：实验采用体重（２５０ ±３０）ｇ 雄性ＳＤ 大鼠２４ 只,分３ 组,每组８ 只,即假手术对照（ＳＣ）组;缺血再灌注（Ｉ／Ｒ） 组和缺血预处理（ＩＰＣ） 组。用超微结构立体计量及羟脯氨酸浓度测定观察心肌间质胶原变化,多道记录仪测量心功能指标,透射电镜观察心肌超微结构。结果：Ｉ／Ｒ 时心肌间质胶原浓度显著低于ＳＣ 组（ Ｐ＜ ０－０１） ,心肌超微结构损伤严重,左室功能明显低于ＳＣ 组（ Ｐ＜ ０－０１） 。ＩＰＣ 组心肌超微结构破坏明显低于Ｉ／ Ｒ 组。同时,心肌间质胶原浓度、胶原纤维线密度及左室功能指标明显高于Ｉ／Ｒ 组（ Ｐ＜ ０－０５ ,Ｐ＜ ０－０１） 。结论：ＩＰＣ 的心肌保护作用不仅表现在对心肌细胞上,而且对心肌间质也有重要的保护作用。     

急性心肌梗死大鼠缺血心肌中差异microRNA的表达谱分析

 目的：筛选急性心肌梗死（AMI）大鼠缺血心肌中差异表达的microRNAs（miRNAs）,预测其靶基因并分析其可能的生物学功能。方法：结扎冠状动脉左前降支建立雄性Wistar大鼠AMI模型,同时检测其心电图和颈总动脉血压变化,并用TTC法测定心肌梗死面积;假手术（sham）组除不结扎冠状动脉左前降支外,其它实验程序与AMI组相同。心肌缺血4 h后取梗死区心肌组织,提取总RNA进行microRNA芯片杂交检测,并用real-time PCR进行验证;生物信息学方法预测差异miRNAs的靶点并分析其生物学功能。结果：心电图、血压检测及病理切片证实AMI模型制备成功。Microarray检测结果表明,与sham组相比,获得11个与急性心肌梗死相关的miRNAs,其中6个miRNAs上调表达,5个miRNAs下调表达;已知3个miRNAs（rno-miR-181c、rno-miR-146b和rno-miR-208）参与了心血管功能的调节,8个miRNAs（rno-miR-672*、rno-miR-743b、rno-miR-128、rno-miR-138-1*、rno-miR-336、rno-miR-138-2*、rno-miR-325-3p和rno-miR-3572）是否与心血管功能有关尚不清楚,可能是心肌梗死相关的新的生物标志物。预测的miRNA靶基因中的一部分亦与心血管功能相关。结论：本研究获得的与AMI相关的差异miRNAs,可能是急性心肌梗死新的生物标志物和潜在的治疗靶点。     

胰岛素对严重烧伤早期大鼠心肌氧化应激的影响

 目的：探讨胰岛素对严重烧伤早期大鼠心肌氧化应激的影响。方法：24只SPF级SD大鼠,随机分为3组,分别是对照组(假烫伤组)、烫伤组和烫伤+胰岛素组。后2组大鼠背部造成30%烧伤总面积(TBSA)的Ⅲ度烫伤,伤后立即腹腔注射生理盐水(40 mL/kg)。烫伤+胰岛素组大鼠复苏补液后皮下注射胰岛素(1 U/kg),烫伤组同法注射等量生理盐水。于伤后24 h采集腹主动脉血和心脏组织标本。采用分光光度法测定血糖(BG)、乳酸脱氢酶(LDH)和肌酸激酶(CK)活性及心脏组织中氧化、抗氧化指标,包括丙二醛(MDA)含量、黄嘌呤氧化酶(XO)、髓过氧化物酶(MPO)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GPx)活性。结果：(1) 烫伤组BG含量与对照组比较显著升高(P＜0.05),烫伤+胰岛素组BG水平较烫伤组显著降低(P＜0.05),与对照组比较显著升高(P＜0.05)。(2) 烫伤组LDH和CK活性与对照组比较显著升高(P＜0.05),烫伤+胰岛素组LDH和CK活性与烫伤组比较显著降低(P＜0.05)。(3) 烫伤组心肌MDA含量、XO与MPO活性与对照组比较显著升高(P＜0.05),SOD、CAT和GPx活性与对照组比较显著降低(P＜0.05);烫伤+胰岛素组心肌MDA含量、XO与MPO活性较烫伤组显著降低(P＜0.05),SOD、CAT和GPx活性较烫伤组显著升高(P＜0.05)。结论：胰岛素干预减轻烧伤后早期大鼠心肌的氧化应激,使升高的心肌酶活性下降,呈现心肌保护效应。     

Metabolic correction reduces the area of acute ischemic myocardial infarction in rats

The possibility of decreasing the degree of irreversible alterations in cardiomyocytes with original saline reperfusion solution enriched with L-aspartic acid, D-glucose, and D-mannitol was studied on experimental rats with regional ischemia and reperfusion. Infusion of the test solution into the left ventricle during the early reperfusion stage significantly reduced the area of myocardial infraction. This effect was accompanied by improvement of energy metabolism and decrease in damage to cell membranes in the risk zone. Our results indicate that metabolic protection during reperfusion increases myocardial resistance to ischemic and reperfusion stress. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 141, No. 3, pp. 267–269, March, 2006     

A comparison of the early development of ischemic brain damage in normoglycemic and hyperglycemic rats using magnetic resonance imaging

The early evolution of ischemic brain injury under normoglycemic and streptozotocin-induced hyperglycemic plasma conditions was studied using magnetic resonance imaging (MRI). Male Sprague-Dawley rats were subjected to either permanent middle cerebral artery occlusion (MCAO), or 1-h MCAO followed by reperfusion using the intraluminal suture insertion method. The animals were divided into four groups each with eight rats: normoglycemia with permanent MCAO, normoglycemia with 1-h MCAO, hyperglycemia with permanent MCAO, and hyperglycemia with 1-h MCAO. Diffusion-weighted images (DWIs) and T2-weighted images (T2WIs) were aquired every l h from 20 min until 6 h after MCAO, at which time cerebral plasma volume images (PVIs) were acquired. Tissue infarction was determined by triphenyltetrazolium chloride staining at 7 h after MCAO. The ischemic damage, measured as the area of DWI and T2WI hyperintensity and tissue infarction, increased significantly in hyperglycemic rats in both permanent and transient MCAO models. In the permanent MCAO model, the maximal apparent water diffusion coefficient (ADC) decline under either normoor hyperglycemia was about 40%, but the speed of ADC drop was faster in hyperlgycemic rats than in normoglycemic rats. Reperfusion after l h of MCAO in normoglycemic rats partly reversed the decline in ADC, whereas the low ADC area continued to expand after reperfusion in the hyperlgycemic group. Between the two hyperglycemic groups with either permanent MCAO or reperfusion, no significant difference was found in the infarct volume measured at 7 h after MCAO. However, reperfusion dramatically increased the extent and accelerated the development rate of vasogenic edema. ADC in the hyperglycemic reperfusion group also dropped to a lower level. A large no-reflow zone was found in the ischemic hemisphere in the hyperglycemic reperfusion group. This study provides strong evidence to support that preischemic hyperglycemia exacerbates ischemic damage in both transient and permanent MCAO models and demonstrates, using MRI, that reperfusion under preischemic hyperglycemia accelerates the evolution of early ischemic injury.     

缺血预处理对糖尿病大鼠缺血/再灌注损伤性心肌超微结构的影响

目的:研究缺血预处理对糖尿病大鼠缺血再灌注损伤性心肌超微结构的影响。方法:建立糖尿病大鼠、缺血再灌注和缺血预处理模型,随机分成6组,即非糖尿病和糖尿病的假手术组、缺血再灌注组、缺血预处理组,观察心肌酶和心肌超微结构变化。结果:非糖尿病的缺血预处理组心肌酶CK、CK-MB、LDH较缺血再灌注组明显降低,心肌超微结构损伤减轻;糖尿病缺血预处理组与缺血再灌注组相比心肌酶无降低,心肌超微结构损伤进一步加重。结论:缺血预处理对非糖尿病大鼠心肌具有保护作用,而对糖尿病大鼠心肌不具有同样的保护作用。     

The role of early parenting in children's development of executive processes

Using structural modeling, we examined the influence of mothers' verbal input that provided information about associations between objects and actions (scaffolding) at 3 and 4 years of age on children's 6-year executive processing skills. Executive processing skills were measured by search retrieval and independent goal-directed play tasks. A set of 4-year basic skills (language, memory, nonverbal problem solving) considered to be prerequisites for executive processing also were included. Patterns of influence across these variables were examined for 253 children who varied in neonatal complications and in their degree of risk for later developmental problems. Results showed that mothers' early verbal scaffolding at 3 years indirectly influenced both types of executive processing skills at 6 years by directly influencing children's language and nonverbal problem-solving skills at 4 years of age. Four-year scaffolding did not show direct influences on later executive processing skills. The provision of this form of maternal verbal input when children are rapidly developing language appears to support a set of basic skills necessary for later executive processing.     

Abnormal myocardial fluid retention as an early manifestation of ischemic injury.

Fifty-seven isolated, blood perfused, continuously weighed canine hearts have been utilized to study the development of abnormal myocardial fluid retention during early myocardial ischemic injury. Inflatable balloon catheters were positioned around the left anterior descending coronary arteries (LAD) of 54 hearts or the proximal left circumflex coronary arteries of three hearts for study of the following intervals of coronary occlusion: a) 10 minutes followed by 20 minutes of reflow, b) 40 minutes followed by either no reflow or by 20 minutes of reflow, and c) 60 minutes without reflow. After 60 minutes of fixed coronary occlusion, histologic and ultrastructural examination revealed mild swelling of many ischemic cardiac muscle cells in the absence of interstitial edema, cardiac weight gain, and obvious structural defects in cell membrane integrity. After 40 minutes of coronary occlusion and 20 minutes of reflow, significant cardiac weight gain occurred in association with characteristic alterations in the ischemic region, including widespread interstitial edema and focal vascular congestion and hemorrhage and swelling of cardiac muscle cells. Focal structural defects in cell membrane integrity were also noted. The development of abnormal myocardial fluid retention after 40 minutes of LAD occlusion occurred in association with a significant reduction in sodium-potassium-ATPase activity in the ischemic area, but with no significant alteration in either creatine phosphokinase or citrate synthase activity in the same region. Despite the abnormal myocardial fluid retention in these hearts, it was possible pharmacologically to vasodilate coronary vessels with adenosine and nitroglycerin infusion to maintain a consistently high coronary flow following release of the coronary occlusion after 40 minutes and to even exceed initial hyperemic flow values following release of the occlusion when adenosine and nitroglycerin infusion was delayed until 15 minutes after reflow. Thus, the data indicate that impaired cell volume regulation and interstitial fluid accumulation and focal structural defects in cell membrane integrity are early manifestations of ischemic injury followed by reflow, but fail to establish a major role for the abnormal fluid retention in altering coronary blood flow prior to the development of extensive myocardial necrosis. In contrast, fixed coronary occlusion for 60 minutes results in mild intracellular swelling but no significant interstitial edema and no obvious structural defects in cell membrane integrity.     

Effects of aging on rat cortical presynaptic cholinergic processes

We studied the effects of aging on the [³H]-choline uptake, acetylation, [³H]-ACh release and muscarinic modulation of [³H]-ACh release in cortical synaptosomes prepared from Fischer 344 male rats. Our results indicate that 6 and 24 month old rats take up and acetylate [³H]-choline to a similar extent, but that the older animals release significantly less [³H]-ACh in response to K⁺-depolarization than the young adults do. This difference in K⁺-induced release is not due to a difference in presynaptic muscarinic receptor inhibitory activity since the older animals appear to be, if anything, slightly less sensitive to oxotremorine than the younger animals are. Atropine (1 μM) had no effect on ACh-release but blocked oxotremorine-induced modulation. Our results suggest that acetylcholine release is decreased in synaptosomes prepared from old rats although the presynaptic muscarinic regulation of release is functional. Thus, muscarinic receptor-mediated release-modulation is a potential site for pharmacologically altering ACh release.