褪黑素对非酒精性脂肪性肝炎大鼠肝脏CYP2E1表达的影响

目的 观察褪黑素(melatonin,MT)对非酒精性脂肪性肝炎大鼠肝脏CYP2E1表达的影响.方法 雄性Wistar大鼠50只,随机分成5组,每组10只,正常对照组予普通饲料,模型组、MT低剂量组、MT中剂量组、MT高剂量组予高脂饮食12周,各MT干预组依次给予MT(含≤1%无水乙醇)2.5 mg·kg-1·d-1、5.0 mg·kg-1·d-1、10 mg·kg-1·d-1腹腔注射,正常对照组、模型组予等量生理盐水(含1%无水乙醇)腹腔注射,12周末进行肝脏病理学检查.生化法测定肝匀浆三酰甘油(TG)、总胆同醇(TC)、超氧化物歧化酶(SOD)、丙二醛(MDA)、谷胱苷肽过氧化物酶(GSH-Px)值,免疫组化法检测肝脏CYP2EI的表达.结果 与正常对照组比较,模型组大鼠肝细胞呈中-重度脂肪变性,肝匀浆TG、TC、MDA值明显升高(P＜0.01);肝匀浆SOD、GSH-Px明显降低,CYP2F1表达强度增加.与模型组比较,各MT干预组肝脏病理变化逐渐改善,肝匀浆TC、TG、MDA值逐渐降低,肝匀浆SOD、GSH-Px活力则逐渐升高,MT高剂量组肝脏CYP2E1表达减弱(P＜0.05).结论 MT能显著抑制非酒精性脂肪性肝炎大鼠肝脏CYP2E1的表达,提高抗氧化酶活性,抑制脂质过氧化反应.     

黄芪总苷对应激大鼠胃黏膜氧自由基及褪黑素受体的影响

目的:探讨黄芪总苷对应激大鼠胃黏膜褪黑素受体基因表达及氧自由基变化的影响.方法:SD大鼠48只分为4组,即正常对照组,模型组,黄芪总苷组和雷尼替丁组,每组12只.采用水浸-束缚应激模型,观察胃黏膜损伤指数,比色法检测胃黏膜SOD活性、MDA含量,RT-PCR法测定褪黑素受体1、2亚型mRNA表达变化.结果:与正常组比较,模型组大鼠胃黏膜损伤指数明显增高,MDA含量增高,SOD活性下降,褪黑素受体1、2基因表达降低,黄芪总苷预防给药后可明显降低应激大鼠胃黏膜损伤指数(6.75±4.10 vs 16.83±4.96,P＜0.01)和MDA含量(0.45±0.07 vs 0.79±0.36,P＜0.05),升高SOD活性(110.62±26.42 vs 71.74±22.20,P＜0.05)和褪黑素受体1、2基因表达(0.86±0.12 vs 0.54±0.05,0.79±0.14 vs 0.50±0.10,均P＜0.01).结论:黄芪总苷对水浸.束缚应激大鼠胃黏膜损伤有保护作用,其保护机制可能与调节胃黏膜褪黑素受体,并参与抗氧自由基损伤有关.     

褪黑激素对应激性溃疡大鼠胃黏膜诱生型一氧化氮合酶表达的影响

背景胃黏膜诱生型一氧化氮合酶(iNOS)的过度表达在应激性溃疡的发生中起重要作用。目的研究褪黑激素(MT)对水浸鄄束缚应激大鼠胃黏膜iNOS表达的影响及其对胃黏膜的保护作用,以进一步阐明MT的作用机制。方法正常对照组不予水浸鄄束缚应激和MT预防,模型组和MT低剂量预防组、MT高剂量预防组于应激前30min分别腹腔注射含1%二甲基亚砜(DMSO)或MT5mg/kg、20mg/kg的等体积生理盐水。应激6h后处死动物,检测各组大鼠胃黏膜一氧化氮(NO)水平、iNOS蛋白和iNOSmRNA的表达,并评估胃黏膜损伤程度。结果水浸鄄束缚应激6h后,大鼠胃黏膜NO水平、iNOS蛋白和iNOSmRNA表达显著增加,胃黏膜病变明显。MT预防组大鼠胃黏膜NO水平、iNOS蛋白和iNOSmRNA表达均显著低于模型组(P<0.01),且溃疡指数(UI)显著下降(P<0.01)。MT高剂量预防组大鼠各检测指标均显著低于MT低剂量预防组(P<0.05),作用呈剂量依赖性。结论MT可预防水浸鄄束缚应激诱导的大鼠胃黏膜损伤,其机制可能与其抑制胃黏膜iNOS过度表达有关。     

褪黑素对糖尿病合并创伤应激大鼠细胞因子及氧化应激的影响

目的 :探讨褪黑素干预治疗对糖尿病合并严重创伤应激大鼠血清TNF α、IL 6及氧化应激指标的影响。方法 :对糖尿病大鼠行左下肢截肢术作为创伤应激 ,术后给予褪黑素 1mg/kg/赋型剂腹腔注射 ,观察术后 2h、6h、12h、2 4h、72h各组大鼠血清TNF α、IL 6、SOD、MDA及GSH水平的变化。结果 :对糖尿病大鼠行截肢术后 ,血清TNF α、IL 6水平升高 ,SOD、GSH水平均明显降低 ,MDA水平明显升高 (P <0 .0 1) ,褪黑素干预组血清TNF α、IL 6水平降低 ,SOD、GSH水平均明显升高 ,MDA水平下降 (P <0 .0 5 )。结论 :褪黑素干预治疗可使糖尿病合并严重创伤应激大鼠前炎症细胞因子下降 ,抗氧化应激能力提高     

损毁孤束核对电针足三里穴抗大鼠应激性胃溃疡作用的影响

目的:探讨孤束核(NTS)在电针(EA)足三里穴抗大鼠应激性胃溃疡中的作用.方法:健康♂SD大白鼠56只随机分为应激组、EA 应激组、NTS电损毁组、NTS假损毁组.通过脑立体定向仪电损毁大鼠孤束核,采用束缚-浸水制备大鼠应激性胃溃疡模型,分别测定各组胃黏膜损伤指数(UI)、超氧化物歧化酶(SOD)活性、丙二醛(MDA)含量.结果:与应激组比较,EA 应激组UI明显减少(t=9.5071,P<0.01),SOD活性升高(t=3.8729,P<0.01),MDA降低(t=2.3578,P<0.05).NTS电损毁组分别与假损毁组和EA 应激组比较UI提高(t=4.4223,7.2579,均P<0.01),SOD活性降低(t=3.5625,3.7242,均P<0.01),MDA含量升高(t=2.9045,2.4960,均P<0.05).结论:电损毁孤束核后,电针足三里穴对应激性胃黏膜损伤的保护作用减弱.     

阿托伐他汀联合辅酶Q10对心肌梗死后心力衰竭大鼠丙二醛、超氧化物歧化酶及心肌纤维化的影响

目的 观察联合应用阿托伐他汀及辅酶Q10对心肌梗死后心衰大鼠丙二醛(MDA)、超氧化物歧化酶(SOD)以及心肌纤维化的影响,探讨阿托伐他汀联合辅酶Q10在治疗心衰中的作用.方法 Wistar大鼠氟烷麻醉后,结扎左冠状动脉前降支,术后6 w成功建立心衰模型.将大鼠随机分为4组(每组6只):假手术组、模型组、模型+阿托伐他汀组、模型+阿托伐他汀+辅酶Q10组,给药组均于术后第7周开始给药,其中阿托伐他汀给药浓度为10 mg·kg-1·d-1,辅酶Q10给药浓度为30 mg·kg-1·d-1,连续给药5 w,1次/d.5 w后硫代巴比妥酸法测定血清中MDA含量,黄嘌呤氧化酶法测定血清中SOD活性,光镜观察心肌纤维化的程度.结果 模型+阿托伐他汀组较模型组血清中MDA含量显著减少(P＜0.01),SOD活性显著增强(P＜0.01),心肌纤维化程度减轻;模型+阿托伐他汀+辅酶Q10组较模型+阿托伐他汀组MDA含量减少(P＜0.05),SOD活性增强(P＜0.05),心肌纤维化程度减轻.结论 阿托伐他汀联合辅酶Q10较单独应用阿托伐他汀能进一步保护心肌,减少心肌梗死后心衰大鼠血清中MDA含量,增加SOD活性,减轻心肌纤维化程度.     

巯基物质对小剂量阿司匹林所致大鼠胃黏膜损伤的保护作用

背景：很多胃黏膜损伤模型中发现巯基物质含量下降，巯基物质对胃黏膜细胞具有保护作用。目的：探讨巯基物质对小剂量阿司匹林所致胃黏膜损伤的保护作用。方法：80只雄性Sprague-Dawley（SD）大鼠随机分为正常对照组、纯巯基对照组、阿司匹林模型组、巯基预防组、硫糖铝预防组、NaCl治疗对照组、巯基治疗组和硫糖铝治疗组8组。测定黏膜溃疡指数（UI），行大体、组织学和透射电子显微镜观察，测定胃黏膜组织中还原型谷胱甘肽（GSH）、超氧化物歧化酶（SOD）、丙二醛（MDA）、6-酮．前列腺素F1α（6-keto-PGF1α）水平。结果：阿司匹林模型组胃黏膜发生病变，UI与其余各组相比显著升高（P〈0．01），GSH、6-keto-PGF1α含量较正常对照组显著降低（P〈0．05），MDA含量显著增高（P〈0.001）。巯基预防或治疗后，胃黏膜损伤明显减轻，UI显著下降（P〈0．001），GSH、6．keto．PGF1α含量显著增高（P〈0．05），MDA含量显著降低（P〈0．05）。各组SOD含量无显著差异。结论：小剂量阿司匹林可致大鼠胃黏膜损伤，胃黏膜GSH下降可能是其机制之一。外源性GSH具有增强胃黏膜抗氧化作用和细胞保护作用。     

西洋参茎叶总皂苷对大鼠实验性心室重构的影响

目的 观察西洋参茎叶总皂苷(PQSs)对大鼠心室重构的影响,并探讨其作用机制.方法 采取结扎大鼠腹主动脉的方法建立压力超负荷性心室重构模型.将70只雄性Wistar大鼠随机分为5组,即:假手术组、模型组、贝那普利(2 mg/kg)组及PQSs 100、50 mg/kg剂量组.假手术组及重构模型组灌胃蒸馏水10 ml*kg-1*d-1,阳性药物组灌胃贝那普利2 mg*kg-1*d-1.给药6 w后观察各组血流动力学相关指标,心肌组织切片,心室脏器系数及体内AngⅡ、内皮素、前列环素、血栓素,SOD、MDA、NO的含量.结果 与模型组比较,PQSs 100、50 mg/kg剂量组及贝那普利(2 mg/kg)组的脏器系数明显减低(P＜0.05或P＜0.01),收缩压、舒张压、平均动脉压以及左室收缩末压明显降低(均P＜0.05),AngⅡ、内皮素、血栓素A2、MDA含量均明显降低(P＜0.05或P＜0.01),而前列环素I2、SOD、NO均明显升高(均P＜0.05或P＜0.01);病理结果显示心室重构不显著.结论 PQSs可显著抑制压力负荷增加所致的心室重构.其作用机制可能是通过改善血流动力学,降低AngⅡ、内皮素含量及升高NO含量,并且有效调节前列环素I2与血栓素A2之间以及SOD与MDA之间的平衡来实现的.     

罗格列酮钠对非酒精性脂肪肝大鼠COX-2表达的影响

目的 探讨罗格列酮钠(RSG)对高脂诱导的非酒精性脂肪肝(NAFLD)大鼠COX-2表达的影响.方法 30只SD大鼠分为对照(CON)组、高脂(HFD)组、RSG组.高脂饮食8 w建立大鼠NAFLD模型,建模后,RSG组灌胃3 mg·kg-1·d-1RSG,CON组及高脂组灌等量蒸馏水,共12 w.测定丙二醛(MDA)、超氧化物歧化酶(SOD)、C反应蛋白(CRP).光镜观察形态学变化,免疫组化法观察COX-2的表达.结果 与CON组相比,HFD组的MDA、CRP升高(P＜0.01),SOD降低(P＜0.01),HFD组出现明显的脂肪变性(P＜0.01),COX-2表达明显增高(P＜0.01).与HFD组相比,RSG组的MDA、CRP降低(P＜0.01),SOD升高(P＜0.01),肝脏脂肪变性减轻(P＜0.01),COX-2表达下降(P＜0.01). 结论 RSG可以减轻高脂诱导的NAFLD大鼠COX-2的表达,从而减轻NAFLD的炎症.     

抗结核药致肝细胞线粒体的氧化损伤

目的 探讨抗结核药对小鼠肝细胞线粒体功能的影响,为减少抗结核药致肝损伤发生提供实验依据.方法 150只昆明种小鼠分成5组,分别为对照组(C组)、利福平(RFP)组、异烟肼(INH)组、吡嗪酰胺(PZA)组以及三种药物的混合组(MIX),分别予0.9％氯化钠溶液0.3 mL/d,RFP 135 mg·kg-1·d-1,INH 90 mg·kg-1·d-1,PZA 315 mg·kg-1·d-1和RFP+ INH+PZA(135+90+315) mg·kg-1·d-1,每天灌胃给药一次,在用药3、7和15 d分批处死小鼠取标本.动态观察各组肝细胞线粒体丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性、谷胱甘肽过氧化物酶(GSH-PX)活性和线粒体DNA(mtDNA)中8羟基脱氧鸟苷(8-OH-dG)含量.采用单因素方差分析或秩和检验.结果 随着用药时间的延长,RFP组(Z=6.020,P=0.049)、INH组(Z=10.220,P=0.006)和MIX组(Z=7.460,P=0.024) MDA含量逐步增高,RFP组(F=6.751,P=0.011)和MIX组(F=4.891,P=0.041)的SOD活性低于对照组和PZA组,RFP组GSH-PX活性明显减低(F=32.445,P＜0.01),其余各组无明显变化规律.各组8-OH-dG含量随用药时间延长均有升高趋势,其中RFP组(F=6.602,P＜0.01)、PZA组(F=5.927,P＜0.01)和MIX组(F=7.974,P＜0.01)升高明显.结论 抗结核药可导致小鼠肝细胞线粒体内MDA和mtDNA中8-OH-dG含量升高,SOD和GSH-PX活性降低.随着用药时间的延长损伤呈加重趋势,三种药物联合用药,可加重对小鼠肝细胞线粒体的损伤程度.     

Recovery of the hypothalamic-pituitary-adrenal response to stress. Effect of stress intensity, stress duration and previous stress exposure

Pathological consequences of stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis may be related to the duration rather than to the intensity of HPA axis activation after exposure to the stressor. Consequently a fine analysis of post-stress events is of importance. The present experiments were designed to study the importance of three key factors in HPA recovery: intensity of the stressor (experiment 1), duration of exposure to the stressor (experiment 2) and previous experience of the animals with the situation (experiments 3 and 4). In experiment 1, analysis of both the response to the stressor and the poststress period showed that the stronger the stressor, the greater the area under the curve of HPA activation. In experiment 2, different groups of rats were exposed to different periods of immobilization (IMO) (20 min, 1 h and 2 h) and sampled before, during and after exposure to IMO. The speed of recovery of plasma corticotropin (ACTH) levels was not related to the duration of exposure to the stressor. In experiments 3 and 4, the influence of previous experience with the stressor was studied in rats daily exposed to 20 min IMO or daily injected with hypertonic saline (HS) for 8 days and sampled on days 1, 2, 5 and 8. Whereas a significant decline in plasma ACTH levels was not observed immediately after IMO until day 8, a single previous exposure to IMO was enough to enhance recovery 90 min after the end of exposure to IMO. Corticosterone levels were related to the number of previous experiences with the stressor only in the post-IMO period. In response to a novel stressor (forced swimming), chronic IMO rats showed a slightly impaired recovery as compared to stress-naive rats, suggesting that enhanced recovery of the HPA axis was specific for the homotypic stressor. After daily HS injections, a pattern similar to that after IMO was observed, the delayed, but not the early response of the HPA axis being reduced as a function of the number of previous experiences with the situation. Taken together, the present results suggest that the speed of recovery of the HPA axis after its activation by stressors is sensitive to the intensity of the stressors but not to their duration, and that adaptation to a repeated stressor is more apparent during the delayed HPA response.     

Long-duration stress

No extensive information exists in literature concerning the late or residual effects of stress on motility of small bowel and colon. Moreover, the duration and magnitude of the intestinal motor response to stress are still ignored. Therefore, the aim of our work was to determine, in rat, the effect of long-duration stress induced by restraint on the motility of small bowel and colon. Observations were made during physical restraint and 60 h later. Bipolar electrodes were implanted on the gastrointestinal serosa from the pylorus to the sigmoid colon in male Wistar rats. Electromyographic (EMG) recordings were made during fasting state, and a control EMG recording session was performed during 12 hr, followed by a 12-hr recording during restraint stress. After a 60-hr resting period, another EMG recording session was performed during 3 hr. During stress in the pylorus and small bowel, the recurrence of migrating myoelectrical complexes (MMCs) was immediately interrupted and replaced by a continuous and irregular activity. The motility index (number of spike bursts/10 min) was augmented rapidly on the jejunum and ileum, but it increased only gradually on the pylorus. Only on the transverse colon were the number of spike bursts/hour and their relative duration increased after 7 hr of physical restraint. In contrast, the sigmoid colon displayed a gradual decrease in the relative duration of contractile activity during the first 6–7 hr of stress. At 60 hr after stress in the pylorus and small bowel, a normal control motor activity was restored (MMC, motility index) on the jejunum and on the ileum, but the motility index on the pylorus was decreased. Throughout the colon, a faster motor activity as well as an increase in the number of spike bursts/hour was observed. In conclusion, a 12hr physical restraint stress induced instant drastic changes in small bowel motility, but a normal motility pattern was rapidly restored after the end of the stress period. However, on the colon, the motor changes are moderate at the beginning of the restraint period, then gradually increased with time, and were still largely persistent three days after the cessation of physical restraint.     

Chronic inflammatory stress

A major mechanism involved in maintaining homeostasis in response to chronic inflammation is the hypothalamo-pituitary-adrenal (HPA) axis, resulting in the release of anti-inflammatory glucocorticoids from the adrenal cortex. An inadequate HPA axis response may result in the development of a pathology or an increase in susceptibility and/or severity of disease. Other neuroendocrine systems are also implicated. Increasingly considered important are circadian rhythms, not only of hormones, but also of components of the immune system. Recent evidence concerning changes in hypothalamic control of the HPA axis following development of disease, the implication of these for the response to stress and the use of the HPA axis as a predictor of susceptibility to disease will also be considered. Finally, the influence of stress on autoimmune disease will be discussed. This chapter will concentrate principally on rheumatoid arthritis, although other autoimmune diseases and animal models will be discussed.     

Hypertension and stress

This study explores the relationship of chronic stress to hypertension. The study included 127 hospitalized and 134 outpatients of a stress treatment program and 129 "normal" persons in the general population. All subjects were matched for age, sex, and race. After three days of hospitalization, there was a 17.3% incidence of hypertension in the hospitalized patients when hypertension was defined as blood pressure levels greater than 140/90 mmHg. These data compare with a 5% and 13% incidence of hypertension in the outpatient stress and "normal" groups, respectively. The National Health Survey of 1962 indicated that 18% of the population were hypertensive. Our data indicate that the incidence of hypertension was no greater in a diagnostically established group of hospitalized stress patients than in the less stressed outpatient or an otherwise "normal" group. The frequently expressed notion that tension and chronic stress predispose a population to essential hypertension is not confirmed by this analysis.     

Pacing stress echocardiography: an alternative to pharmacologic stress testing

OBJECTIVES: We sought to evaluate the diagnostic accuracy and feasibility of bedside pacing stress echocardiography (PASE) as a potential substitute for pharmacologic stress echocardiography in patients admitted to the hospital with new-onset chest pain or worsening angina pectoris. BACKGROUND: Accurate and rapid noninvasive identification and evaluation of the extent of coronary artery disease (CAD) is essential for optimal management of these patients. METHODS: Bedside transthoracic stress echocardiography was performed in 54 consecutive patients admitted to a community hospital with new-onset chest pain, after acute myocardial infarction had been excluded. We used 10F transesophageal pacing catheters and a rapid and modified pacing protocol. The PASE results were validated in all patients by coronary angiography performed within 24 h of the test. Significant CAD was defined as > or =75% stenosis in at least one major epicardial coronary artery. RESULTS: The sensitivity of PASE for identifying patients with significant CAD was 95%, specificity was 87% and accuracy was 92%. The extent of significant CAD (single- or multivessel disease) was highly concordant with coronary angiography (kappa = 0.73, p<0.001). Pacing stress echocardiography was well tolerated, and only 4% of the patients had minor adverse events. The mean rate-pressure product at peak pacing was 22,313+/-5,357 beats/min per mm Hg, and heart rate >85% of the age-predicted target was achieved in 94% of patients. The average duration of the bedside PASE test, including image interpretation, was 38+/-6 min. CONCLUSIONS: Bedside PASE is rapid, tolerable and accurate for identification of significant CAD in patients admitted to the hospital with new-onset chest pain or worsening angina pectoris.     

Quantitative stress echocardiography

Dramatic improvements in our ability to treat coronary artery disease have created the need to develop sensitive and specific noninvasive tests for diagnosing and assessing the severity of ischemic disease. The purpose of this review is to examine stress echocardiography and, in particular, quantitative stress echocardiography in this context. Methodology and technical aspects of performing and interpreting stress echocardiography are discussed, including the type of exercise performed, imaging and recording techniques, and methods for on-line and off-line analysis. Qualitative, semiquantitative, and quantitative approaches are compared and contrasted. In assessing quantitative stress echocardiography, the role of global measurements of left ventricular function including ejection fraction, peak systolic pressure to end-systolic volume index ratio, as well as regional measurements including wall-motion analysis and wall stress, are discussed. Pertinent literature using quantitative approaches is reviewed including those comparing quantitative stress echocardiography with other noninvasive modalities. Future directions for study are also addressed. We concluded that quantitative stress echocardiography has excellent sensitivity and specificity for diagnosing ischemic heart disease. It was useful in localizing lesions, defining multivessel disease, and predicting patients with poor prognosis postmyocardial infarction. Its reproducibility makes it a valuable technique in following patients noninvasively over time.