ANP gene expression in rat hearts during hypoxia

 It is unclear whether the increase in plasma atrial natriuretic peptide (ANP) concentration during hypoxia is due to direct, hypoxia-induced upregulation of ANP secretion in the heart, or to pressure overload of the right ventricle (RV) following hypoxia-induced pulmonary hypertension. To test the hypothesis that hypoxia leads to an early upregulation of the ANP gene, we examined the influence of acute and prolonged inspiratory hypoxia (6 h, 1 or 3 weeks) on the expression of ANP messenger ribonucleic acid (mRNA) in rat heart and compared the results with the expression of the ANP gene after acute pressure overload induced by experimental coarctation of the main pulmonary artery. As a molecular marker for hypertrophy we determined the ratio of α- and β-myosin gene expression. Hypoxia increased systolic RV pressure from 20.0 ± 1.6 mmHg to 27.8 ± 1.6 mmHg (P < 0.01) and 41.6 ± 2.1 mmHg (P < 0.05) after 1 and 3 weeks hypoxia respectively. The ANP plasma concentration did not change significantly after 6 h or 1 week: 232 ± 21 pg/ml (control), 246 ± 25 pg/ml (6 h), 268 ± 25 pg/ml (1 week), but increased significantly after 3 weeks hypoxia (446.8 ± 99.56 pg/ml; P < 0.05). ANP mRNA levels in different regions of the heart did not change after 6 h or 1 week hypoxia. After 3 weeks hypoxia ANP mRNA had increased 2.7-fold in the RV (P < 0.05), 4.2-fold in the left ventricle (LV, P < 0.05), 3.5-fold in the septum (S, P < 0.05) and about 1.4-fold in the right (n.s.) and left atrium (n.s.). Relative ventricular masses increased significantly only for the RV (190%, P < 0.05) during hypoxia. The β/α-myosin mRNA ratio did not change after 6 h hypoxia but, contrary to ANP gene expression, increased after just 1 week (6.1-fold in RV, 7.8-fold in LV, 6-fold in S; P < 0.05) and was more pronounced in the RV after 3 weeks (9.4-fold in RV, 7.6-fold in LV, 9.1-fold in S; P < 0.05). The increase in the β/α-myosin mRNA ratio in the LV contrasts with a lack of increase in relative ventricular mass. Acute pressure overload in the RV after pulmonary arterial banding significantly increased ANP-mRNA and the β/α-myosin mRNA ratio after 1 day in the RV. In the LV ANP mRNA was unchanged. The delayed upregulation of the ANP gene suggests that hypoxia per se is not a significant stimulus for ANP gene expression in the heart and that hypoxia-induced ANP-gene expression in the heart is regulated predominantly by the increase in RV afterload due to hypoxia-induced increased pulmonary pressure. The upregulation of ANP and β-myosin mRNA in the LV during chronic hypoxia has yet to be elucidated. Received: 5 November 1996 / Received after revision and accepted: 24 January 1997     

Exercise-induced physiological hypertrophy initiates activation of cardiac progenitor cells

Objective: Physiological hypertrophy is featured by the hypertrophy of pre-existing cardiomyocytes and the formation of new cardiomyocytes. C-kit positive cardiac progenitor cells increased their numbers in exercise-induced physiological hypertrophy. However, the participation of Sca-1 positive cells in the physiological adaptation of the heart to exercise training is unclear. Methods: Physiological hypertrophy was induced by swimming and the mRNA levels of GATA binding protein 4 (GATA4), atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), endogenous hepatocyte growth factor (HGF), and insulin like growth factor-1 (IGF-1) from the whole heart were determined by real-time polymerase chain reactions (RT-PCRs) analysis. Immunofluorescent staining was used to compare the number of C-kit and Sca-1 positive cardiac progenitor cells. In addition, mRNA levels of C-kit and Sca-1 in left ventricle (LV), right ventricle (RV), and outflow tract (OFT) were determined in mice swimming for 7, 14, and 21 days by RT-PCRs. Results: The ratio of heart weight (HW) to body weight and HW to tibia length and the mRNA level of GATA4 were increased while mRNA levels of ANP and BNP remained unchanged. C-kit and Sca-1 positive cardiac progenitor cells were activated by swimming training. An increased endogenous production of HGF and IGF was observed at least at the mRNA level. Swimming induced a significant up-regulation of C-kit in LV of mice swimming for 1, 2 and 3 weeks and in RV of mice swimming for 3 weeks. Sca-1 positive cardiac progenitor cells were increased in LV and OFT in mice swimming for 3 weeks. Conclusion: This study presents that swimming-induced physiological hypertrophy initiates activation of cardiac progenitor cells.     

Increased cardiac weight in interleukin-6 transgenic mice with viral infection accompanies impaired expression of natriuretic peptide genes

Atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) regulate cardiac hypertrophy. We investigated ventricular alterations of ANP and BNP in interleukin-6 (IL-6) transgenic mice (TG) and wild type (WT) mice with or without viral infection. The ANP and BNP mRNA/GAPDH mRNA ratios in the ventricles of IL-6 TG mice were twice that of WT mice, but were not increased significantly by viral inoculation. In WT mice, both ANP and BNP responses were significantly increased in the ventricles of mice 10 days after encephalomyocarditis (EMC) viral inoculation. Cardiac weight in IL-6 TG mice was significantly greater than in WT 10 days after viral inoculation. Left ventricular wall thickness and the diameter of ventricular myocytes also were greater in IL-6 TG than WT after viral infection. Primary cultures of neonatal rat cardiac myocyte showed that IL-6 increased ANP and BNP mRNA expression in a dose-responsive fashion. In summary, overexpression of ANP and BNP occurs in the ventricles of IL-6 TG mice, along with increased cardiac weight after infection with EMC virus, and impaired responses in the expression of ANP and BNP.     

雌激素及其受体对低氧性肺血管重建的作用

 目的：探讨雌激素及其受体对低氧性肺血管重建的作用。 方法:采用间断常压低氧法建立大鼠低氧性肺动脉高压模型。将30只雄性SD大鼠随机分成：对照组、雌激素预防组、低氧组、雌激素治疗组、治疗对照组。以右心导管法测定平均肺动脉压(mPAP)；测定右心室肥厚指数［RV/(LV+S)］；图像分析技术测定肺小血管管壁厚度；用放射免疫法测定血清17-β雌二醇浓度。用RT-PCR方法检测肺组织中ERβ mRNA的表达，用免疫组化染色法检测肺小血管壁的ERβ蛋白表达。 结果:①低氧组、治疗对照组大鼠mPAP、RV/(LV+S)、WT%和WA%均高于对照组；雌激素预防组、雌激素治疗组大鼠mPAP、RV/(LV+S)、WT%和WA%均低于低氧组、治疗对照组。②低氧组、治疗对照组大鼠ERβ mRNA表达量和ERβ蛋白表达与正常对照组无差异。经雌激素干预后，雌激素预防组、雌激素治疗组的ERβ mRNA表达和ERβ蛋白表达显著高于低氧组、治疗对照组。 结论:17-β雌二醇能有效降低低氧性肺动脉高压大鼠的肺动脉压力、阻抑右心室肥厚,对低氧性肺动脉高压血管重建具有一定的预防和治疗作用，其作用可能是通过雌激素受体β实现的。     

Role of anterior hypothalamic natriuretic peptide in lipopolysaccharide-induced fever in rats

We investigated whether within the preoptic area, natriuretic peptide (NP) acts as an endogenous antipyretic in rats made febrile by systemic administration of bacterial endotoxin (lipopolysaccharide, LPS). Intravenous (i.v.) injection of LPS (2 μg/kg) induced a triphasic fever. The third phase of this fever was (a) significantly enhanced by an intrapreoptic (i.p.o.) injection of the NP-receptor (A-type and B-type) antagonist HS-142-1(1 μg), and (b) significantly attenuated by an i.p.o. injection of atrial NP (ANP, 20 ng). When given i.v., LPS induced significant upregulation of the mRNA coding for C-type NP within the anterior hypothalamus, and tended to upregulate that for ANP. The anterior hypothalamic expression of interleukin-1β mRNA was significantly greater in rats injected i.v. with LPS than in saline-injected rats. These results suggest that NPs produced within the anterior hypothalamus after i.v. injection of LPS may act upon preoptic NP receptors to inhibit the LPS-induced fever, possibly through attenuation of the LPS-induced production of proinflammatory cytokines and/or the subsequent final fever mediator prostaglandin E₂.     

静脉注射IL-19重组质粒对大鼠实验性自身免疫性心肌炎的治疗作用

目的:评估静脉注射白细胞介素19(interleukin-19,IL-19)重组质粒对大鼠实验性自身免疫性心肌炎(experimental autoimmune myocarditis,EAM)的治疗作用。方法:将猪心室肌球蛋白与等体积完全弗氏免疫佐剂充分混匀后,双足皮下注射制作大鼠EAM模型,免疫后第6天应用静脉注射方法将IL-19重组质粒导入体内,第17天行心脏超声检查后处死大鼠,检测心脏重量与体重比值、病理学评估、心肌炎面积率;实时荧光定量PCR检测心衰标记物心房钠尿肽(atrial natriuretic peptide,ANP)、脑钠尿肽(brain natriuretic peptide,BNP)的表达水平,进一步检测心肌相关炎症因子IL-18、IL-1β、IL-12p35和IFN-γ的表达水平。结果:IL-19重组质粒导入组的大鼠心功能得到显著改善;心脏重量体重比、心肌炎面积率、ANP、BNP的表达均较模型组明显下降;相关炎症细胞因子的表达也显著降低。结论:应用静脉注射法进行IL-19重组质粒体内导入治疗,明显抑制大鼠实验性自身免疫性心肌炎的炎症反应,减轻了心肌损伤从而改善心功能。     

Ghrelin抑制大鼠心肌梗死后心室重构

目的:探讨Ghrelin对大鼠心肌梗死后心室重构的影响及其机制。方法:结扎SD大鼠前降支造成急性心肌梗死(AMI)模型,并设假手术组。结扎24h后,存活大鼠给予Ghrelin(100μg/kg)或生理盐水皮下注射,每天两次。4周后,超声心动图和血流动力学方法检测心功能,实时定量PCR检测梗死心肌白介素-1β(IL-1β)、肿瘤坏死因子-α(TNF-α)mRNA表达,Western-blot检测核转录因子-κB(NF-κB)活性。结果:与假手术组相比,AMI模型组左室收缩内径(LVESD)、左室舒张内径(LVEDD)、左室舒张末压力(LVEDP)都明显增加(P<0.01);而左室收缩压(LVSP)、压力变化值最大值(dp/dtmax)、左室短轴缩短率(FS)都显著降低(P<0.01)。与AMI模型组相比,Ghrelin治疗组LVEDP、LVEDD以及LVESD明显变小(P<0.01),而dp/dtmax及FS显著增加(P<0.01)。梗死后心肌IL-1β、TNF-αmRNA表达增强,Ghrelin治疗后IL-1β、TNF-αmRNA表达明显降低(P<0.01)。AMI模型组心肌核蛋白P65表达明显增加,而胞浆蛋白I-κBα含量显著减少(P<0.01),Ghrelin治疗明显降低梗死心肌核蛋白P65表达(P<0.01),同时增加胞浆蛋白I-κBα含量(P<0.01)。结论:Ghrelin能够抑制心肌梗死后心室重构,改善心功能,可能与其抑制炎症介质表达及NF-κB活性有关。     

Gene expression profiling of exercise‐induced cardiac hypertrophy in rats

Aims: Exercise training causes physiological cardiac hypertrophy, which acts to enhance cardiac function during exercise. However, the underlying molecular mechanisms are unclear. We investigated gene expression profile of exercise training‐induced cardiac hypertrophy using left ventricle (LV) excised from exercise‐trained and sedentary control rats (12‐week old). Method: Rats in the training group exercised on a treadmill for 8‐week. Results: Left ventricular mass index and wall thickness in the exercise‐trained group were significantly greater than that in the control group, indicating that the trained rats developed cardiac hypertrophy. Of the 3800 genes analysed in the microarray analyses, a total of 75 relevant genes (upregulation of 33 genes and downregulation of 42 genes) displayed alterations with exercise training. Among these genes, we focused on glycogen synthase kinase (GSK)‐3β, calcineurin‐inhibitor (Cain), and endothelin (ET)‐1 for their implicated roles in pathological cardiac hypertrophy, and confirmed the results of microarray analysis at mRNA and protein/peptide levels using quantitative PCR, Western blot, and EIA analyses. The gene expression of GSK‐3β decreased significantly and those of Cain and ET‐1 increased significantly with exercise training. Furthermore, LV mass index was significantly correlated with GSK‐3β protein activity (r = ?0.70, P < 0.01) and tissue ET‐1 concentration (r = 0.52, P < 0.05). There were no changes in gene expressions in brain natriuretic peptide (BNP), angiotensin‐correcting enzyme (ACE), interleukin‐6, and vascular cell adhesion molecule (VCAM)‐1. Conclusion: These findings suggest that physiological and pathological LV hypertrophy may share some of the same molecular mechanisms in inducing LV hypertrophy (e.g. GSK‐3β, Cain, and ET‐1) and that other genes (e.g. BNP, ACE) may differentiate physiological from pathological LV hypertrophy.     

肾上腺髓质素m RNA在慢性缺氧大鼠右心室中的表达

目的:探讨肾上腺髓质素(AM)在慢性低氧性肺动脉高压发病中的作用。方法:16只大鼠随机分为低氧组和对照组,间断常压低氧14d复制肺动脉高压模型,静脉右心导管测定右室收缩压(RVSP)的变化,分离心室检测右室/(左室+室间隔)(RV/LV+SP)比值,原位杂交法检测AMmRNA在右心室中的表达。结果:低氧组大鼠右室压为(63.63±3.42)mmHg,显著高于对照组的(34.13±3.40)mmHg(P<0.01)。低氧组大鼠(RV/LV+SP)比值为0.439±0.039,显著高于对照组的0.23±0.025(P<0.01)。AMmRNA在对照组大鼠的右室心肌细胞也有少量表达,低氧组大鼠其表达显著多于对照组。图像分析表明,低氧组的平均吸光度、平均表达面积分别为0.1061±0.0188,0.1421±0.0165,均显著高于对照组的0.0872±0.0171,0.0967±0.0135。结论:低氧时右心室AMmRNA表达增加,提示可能在肺动脉高压的发病中起保护作用。     

慢性低氧性肺动脉高压大鼠肾上腺髓质素前体N端20肽的变化

目的：探讨慢性低氧性肺动脉高压和肺血管结构重建时肾上腺髓质素前体N端20肽（PAMP）的变化。方法:将18只雄性Wistar大鼠随机分为对照组和低氧组，每组各9只。常压低氧2周后，以右心导管法测定肺动脉平均压（mPAP），检测右心室与左心室加室间隔比值 ［RV/(LV+S)］，观测肺血管显微和超微结构的变化。并且以放免法测定血浆中PAMP含量，以免疫组化法检测肺组织中PAMP表达，以原位杂交检测肺组织中肾上腺髓质素（ADM） mRNA的表达。结果: 低氧组大鼠mPAP及RV/（LV+S）均明显高于对照组（均P<0.01）。光镜下，肺小血管肌化程度明显增强，肺中、小型肌型动脉相对中膜厚度明显增加。电镜下，肺腺泡内动脉内皮细胞增生、肿胀，内弹力层粗细不均，平滑肌细胞肥厚、向合成表型转化。并且低氧组大鼠血浆PAMP含量明显高于对照组（P<0.01），肺动脉PAMP表达和ADM mRNA表达均明显增强。结论：低氧后肺动脉PAMP表达和血浆PAMP含量的上调可能参与了慢性低氧性肺动脉高压和肺血管结构重建的形成。     

Remote myocardium gene expression after 30 and 120 min of ischaemia in the rat

The aim of the present study was to investigate how early the onset of ischaemia-induced changes in gene expression is in remote myocardium, and whether these changes would be different for left and right ventricles. Wistar rats (n=27) were randomly assigned to left coronary artery (LCA) ligation for 30 or 120 min and sham groups. Evans Blue infusion revealed antero-apical left ventricle (LV) and left intraventricular (IV) septal ischaemia (35.5+/-0.6% of LV mass). LCA ligation induced transient LV systolic dysfunction and sustained biventricular slowing of relaxation. Regarding mRNA levels, type B natriuretic peptide (BNP) was upregulated in the LV at 30 (+370+/-191%) and 120 min (+221+/-112%), whilst in the right ventricle (RV) this was only significant at 120 min (+128+/-39%). Hipoxia-inducible factor 1alpha and interleukin 6 overexpression positively correlated with BNP. Inducible NO synthase upregulation was present in both ventricles at 120 min (LV, +327+/-195%; RV, +311+/-122%), but only in the RV at 30 min (+256+/-88%). Insulin-like growth factor 1 increased in both ventricles at 30 (RV, +59+/-18%; LV, +567+/-192%) and 120 min (RV, +69+/-33%; LV, +120+/-24%). Prepro-endothelin-1 was upregulated in the RV at 120 min (+77+/-25%). Ca2+-handling proteins were selectively changed in the LV at 120 min (sarcoplasmic reticulum Ca2+ ATPase, 53+/-7%; phospholamban, +31+/-4%; Na+-Ca2+ exchanger, 31+/-6%), while Na+-H+ exchanger was altered only in the RV (-79+/-5%, 30 min; +155+/-70%, 120 min). Tumour necrosis factor-alpha and angiotensin converting enzyme were not significantly altered. A very rapid modulation of remote myocardium gene expression takes place during myocardial ischaemia, involving not only the LV but also the RV. These changes are different in the two ventricles and in the same direction as those observed in heart failure.     

慢性心力衰竭大鼠内皮素系统表达的变化

目的:研究慢性心衰大鼠在心衰早期(冠脉结扎10d)和心衰晚期(冠脉结扎70d)的左心室内皮素受体A(ET_AR)和内皮素受体B(ET_BR)及内皮素前体(PreproET₁)的mRNA表达水平,了解心衰时心肌内皮素系统的变化及其与病程的关系。方法:用逆转录-聚合酶链反应(RT-PCR)检测冠脉结扎心衰模型大鼠的左心室ET_A和ET_B受体及PreproET₁的mRNA表达,以放射免疫技术检测血浆中内皮素(ET₁)和心钠素(ANP)的浓度。结果:冠脉结扎10d后,血浆ET₁、ANP的水平和左心室ET_AR、ET_BR、PreproET₁的mRNA表达水平均明显高于假手术组;冠脉结扎70d后,血浆ET₁和ANP的水平显著高于冠脉结扎10d组和假手术组,ET_A受体mRNA表达水平和假手术组相比无显著性差异,而ET_B受体及PreproET₁mRNA表达水平仍明显高于假手术组,但显著低于冠脉结扎10d组。结论:在慢性心衰的不同阶段,左心室内皮素系统的改变参与机体心脏功能的调节,循环ET₁水平的上升在早期主要是由于PreproET₁的mRNA表达上调所致,在后期则主要与下调的内皮素受体水平有关。     

多胺在L-精氨酸抑制异丙肾上腺素诱导的大鼠心肌肥厚中的作用

目的： 研究多胺在L-精氨酸抑制病理性心肌肥厚中的作用及机制。方法：异丙肾上腺素（ISO）皮下注射复制大鼠心肌肥厚模型,L-精氨酸作为干预因素,检测心脏肥大指数,心肌组织胶原染色,心房利钠肽（ANP）的转录水平,观察L-精氨酸对心肌肥大的影响;不同时段,应用高效液相色谱仪（HPLC）测定心肌组织内多胺含量,应用Western blotting结合图像分析系统,检测各组大鼠心肌组织鸟氨酸脱羧酶（ODC）和精眯/精胺乙酰转移酶（SSAT）的蛋白表达水平;检测血清NO含量和NOS活性。结果：皮下注射ISO7d后,心肌肥大指数增加,心肌纤维增粗、排列紊乱,ANP mRNA表达增加;L-精氨酸干预可抑制ISO诱导的心肌肥大,随着L-精氨酸作用时间延长,心肌组织多胺含量减少,血清NOS活性增强,NO含量增加。同时,ODC蛋白表达下调,SSAT蛋白表达上调。结论：L-精氨酸抑制ISO诱导的心肌肥大,其机制可能与下调L-精氨酸/多胺通路、上调L-精氨酸/NO通路有关。     

ECE1过表达通过eNOS/NO通路促进AngⅡ诱导的体外培养大鼠心肌细胞肥大和凋亡

目的:探讨过表达内皮素转换酶1(ECE1)对血管紧张素Ⅱ(AngⅡ)诱导的体外培养大鼠H9C2心肌细胞肥大和凋亡的影响.方法:采用AngⅡ作用于体外培养的H9C2心肌细胞,建立心肌细胞肥大模型.将细胞分为空白对照组、AngⅡ组、AngⅡ+质粒空载体(AngⅡ+NC)组和AngⅡ+ECE1过表达组.CCK-8法检测细胞活...     

Increased oxytocinergic system activity in the cardiac muscle in spontaneously hypertensive SHR rats

IntroductionThe present study aimed to determine whether the presence of cardiac hypertrophy due to arterial hypertension is associated with a change in the activity of the oxytocinergic system in cardiomyocytes.Material and methodsThe experiments were performed on male, spontaneously hypertensive rats (SHR, n = 10) and normotensive Wistar-Kyoto rats (WKY, n = 12). Blood samples were collected from both SHR and WKY animals to asses plasma oxytocin (OT) concentration; the rats were sacrificed by decapitation. Samples of the left and right ventricles were harvested for the analysis of the OT and oxytocin receptor (OTR) protein by ELISA, and OT and OTR mRNA expression by RT-PCR. Immunohistopathological studies were performed to confirm the presence of OTR receptors in the cardiac muscle of the ventricles.ResultsPlasma OT concentration did not differ between SHR and WKY rats. In the SHR rats, the expression of OT mRNA and the OT protein level was higher in the left and the right ventricle, while OTR mRNA expression was significantly lower in both the left and the right ventricle. However, the level of OTR protein was higher only in the left ventricle of the SHR rats. The presence of OTR receptors was confirmed by immunohistochemical analysis in the muscle of the right and left ventricle.ConclusionsThe presence of arterial hypertension is associated with increased activity of the oxytocinergic system in the heart, especially in the area of the left ventricle. These findings support the important role of this system in the maintenance of cardiovascular homeostasis.     

异甘草素对低氧诱导的大鼠肺动脉结构重建的影响

目的 观察异甘草素对缺氧性肺动脉高压（HPH）大鼠模型的肺动脉压力的变化,右心室肥厚程度及肺血管结构重建的影响,探讨异甘草素对HPH的抑制作用及其可能机制。方法 雄性SD大鼠30只随机分为对照组、HPH组、异甘草素组,每组各10只。HPH组和异甘草素组大鼠置于缺氧箱中建立大鼠HPH模型。异甘草素组中,每只大鼠腹腔注射异甘草素剂量为10 mg/(kg·d),从缺氧前1周开始给药直到缺氧结束。对照组和HPH组大鼠腹腔注射等体积0.5% DMSO。测定各组大鼠平均右心室压力(RVSP);称重法测得各组大鼠右心室游离壁（RV）及左心室加室间隔（LV+S）质量,以及RV/（LV+S）;HE染色观察肺动脉病理形态改变,计算血管厚度百分比(WT%)及面积百分比(WA%);ELISA法检测各组大鼠血清及肺组织中的超氧化物歧化酶(SOD)及丙二醛(MDA)的含量。Real-time PCR检测各组大鼠肺组织中的NADPH氧化酶4(NOX4) mRNA的表达。结果 HPH组大鼠RVSP、RV/LV+S、WT%,以及WA%明显高于对照组大鼠（P<0.01）,然而异甘草素组大鼠RVSP、RV/LV+S、WT%,以及WA%均明显低于HPH组大鼠（P<0.01）。HPH组大鼠肺组织及血清中的SOD含量较对照组明显降低,而MDA含量则明显增高（P<0.01）。异甘草素组大鼠肺组织及血清中的SOD含量较HPH组大鼠明显增高,而MDA含量则明显降低（P<0.01）。 Real time PCR结果显示,异甘草素有效抑制了低氧诱导的大鼠肺组织中NOX4 mRNA的高表达（P<0.01）。结论 异甘草素抑制由低氧诱导的HPH大鼠肺动脉压力升高、右心室肥厚,以及肺动脉管壁的增厚,可能与异甘草素抑制HPH大鼠体内的氧化损伤有关。     

Inhibition of microglial inflammatory responses by norepinephrine: effects on nitric oxide and interleukin-1β production

Background

Under pathological conditions, microglia produce proinflammatory mediators which contribute to neurologic damage, and whose levels can be modulated by endogenous factors including neurotransmitters such as norepinephrine (NE). We investigated the ability of NE to suppress microglial activation, in particular its effects on induction and activity of the inducible form of nitric oxide synthase (NOS2) and the possible role that IL-1β plays in that response.

Methods

Rat cortical microglia were stimulated with bacterial lipopolysaccharide (LPS) to induce NOS2 expression (assessed by nitrite and nitrate accumulation, NO production, and NOS2 mRNA levels) and IL-1β release (assessed by ELISA). Effects of NE were examined by co-incubating cells with different concentrations of NE, adrenergic receptor agonists and antagonists, cAMP analogs, and protein kinase (PK) A and adenylate cyclase (AC) inhibitors. Effects on the NFκB:IκB pathway were examined by using selective a NFκB inhibitor and measuring IκBα protein levels by western blots. A role for IL-1β in NOS2 induction was tested by examining effects of caspase-1 inhibitors and using caspase-1 deficient cells.

Results

LPS caused a time-dependent increase in NOS2 mRNA levels and NO production; which was blocked by a selective NFκB inhibitor. NE dose-dependently reduced NOS2 expression and NO generation, via activation of β2-adrenergic receptors (β2-ARs), and reduced loss of inhibitory IkBα protein. NE effects were replicated by dibutyryl-cyclic AMP. However, co-incubation with either PKA or AC inhibitors did not reverse suppressive effects of NE, but instead reduced nitrite production. A role for IL-1β was suggested since NE potently blocked microglial IL-1β production. However, incubation with a caspase-1 inhibitor, which reduced IL-1β levels, had no effect on NO production; incubation with IL-receptor antagonist had biphasic effects on nitrite production; and NE inhibited nitrite production in caspase-1 deficient microglia.

Conclusions

NE reduces microglial NOS2 expression and IL-1β production, however IL-1β does not play a critical role in NOS2 induction nor in mediating NE suppressive effects. Changes in magnitude or kinetics of cAMP may modulate NOS2 induction as well as suppression by NE. These results suggest that dysregulation of the central cathecolaminergic system may contribute to detrimental inflammatory responses and brain damage in neurological disease or trauma.     

三七总皂苷对低氧大鼠肺动脉压和肺组织p38 MAPK表达的影响

目的:探讨三七总皂苷(PNS)对低氧大鼠p38丝裂原活化蛋白激酶(p38 MAPK)表达的影响,及预防低氧性肺动脉高压(HPH)的作用和机制。方法:将30只SD大鼠随机分为3组:正常对照组、低氧组和低氧+PNS组。观察各组大鼠平均肺动脉压(mPAP)、平均颈动脉压(mCAP)和右心室/(左心室+室间隔重量)比[RV/(LV+S)],免疫组化法和RT-PCR法分别检测肺小血管壁磷酸化p38 MAPK(p-p38 MAPK)蛋白和肺组织中mRNA的含量。结果:与对照组相比,低氧组大鼠mPAP、RV/(LV+S)明显升高,肺小动脉p-p38 MAPK及肺组织p38 MAPK mRNA含量显著升高(P0.05)。低氧+PNS组mPAP、RV/(LV+S)、肺小动脉p-p38 MAPK及肺组织p38 MAPK mRNA含量明显低于低氧组(P0.05)。结论:PNS具有显著预防HPH的作用,其机制可能与其降低p38 MAPK mRNA的表达有关。     

Athymic nude rats develop severe pulmonary hypertension following monocrotaline administration

OBJECTIVE: To investigate the significance of the presence or absence of the thymus in the development of pulmonary hypertension (PH) following monocrotaline (MCT) administration, the degree of MCT-induced PH (MCT-PH) in athymic nude (F344/N Jcl-rnu) rats was compared with that in their euthymic (rnu/+) littermates. METHODS: Histopathological studies of the lung in terms of interstitial edema, congestion, thickening of the alveolar wall, inflammatory cell infiltration and degeneration of arteries were performed by staining with hematoxylin-eosin (HE), elastin van Gieson and Masson's trichrome. The medial wall thickness of the small pulmonary arteries and the weight ratio of the right ventricular free wall (RV) to that of the left ventricle plus septum [RV/(LV + S) weight ratio] were used as indices of the degree of PH. Toluidine blue staining was performed to estimate the number of the mast cells in the lung interstitium. RESULTS: Interstitial edema was significantly severer in MCT- injected euthymic rats than in MCT-injected athymic nude rats (p < 0.01); in contrast, the thickening of the alveolar wall was severer in MCT-injected athymic nude rats than in MCT-injected euthymic rats (p < 0.05). The degree of MCT-PH, as determined by the medial wall thickness of the small pulmonary arteries and RV/(LV + S) weight ratio in MCT-injected athymic nude rats, was significantly severer than in MCT-injected euthymic rats (p < 0.05 and p < 0.01, respectively). The number of mast cells was significantly greater in MCT-injected athymic nude rats than in MCT-injected euthymic rats (p < 0.01). The degree of the medial wall thickness of the small pulmonary arteries was significantly correlated with RV/(LV + S) weight ratio (p < 0.05) as well as with the number of mast cells in MCT-injected rats. CONCLUSIONS: Athymic nude rats developed severer PH than euthymic rats along with a greater number of mast cells and severer histopathological changes, such as thickening of the alveolar wall. Mast cell proliferation was considered to play a pivotal role in the development of PH in MCT-PH.