Effect of verapamil on monocrotaline-induced pulmonary artery hypertension and endothelial cell dysfunction in rats

Verapamil, a calcium channel blocker has been used with partial success in cases of primary pulmonary hypertension, as well as to reduce hypoxia-induced pulmonary hypertension (PH) in rats. However, its effect on monocrotaline (MCT)-induced PH in rats is not known. We studied the effect of verapamil on MCT-induced PH. Three weeks after a single injection of MCT, significant PH was noted in the MCT-injected rats compared with control (44.35 +/- 3.5 vs. 22 +/- 2.5 mmHg). MCT-injected rats on daily verapamil showed significant reduction in PH (31.5 +/- 3.4 mmHg). The main pulmonary artery of MCT-injected rats revealed subendothelial thickening, thinning and fragmentation of elastic laminae, smooth muscle cell hypertrophy and necrosis or loss of smooth muscle cells, and increased amounts of collagen in media and adventitia. In contrast, the main pulmonary artery of MCT + VP-treated rats showed less intimal thickening, some smooth muscle cell hypertrophy, but little necrosis or loss of cells in addition to disappearance of outer elastic laminae. Smaller pulmonary arteries (less than 150 microns in diameter) in MCT + VP-treated rats showed less medial thickening than MCT groups. However, diminished lung angiotensin-converting enzyme activity suggestive of endothelial cell dysfunction was noted in both MCT and MCT + VP-treated rats. This study indicates that verapamil attenuates MCT-induced PH, but has no effect on pulmonary endothelial cell dysfunction.     

Peroxisome proliferator-activated receptor gamma ligands inhibit Rho/Rho kinase pathway by inducing protein tyrosine phosphatase SHP-2

Although peroxisome proliferator-activated receptor gamma (PPARgamma) ligands have an antihypertensive effect in vivo, the precise mechanism has not been fully elucidated. We examined their effects on Rho/Rho kinase pathway, a key regulator of vascular tone. In cultured rat aortic smooth muscle cells (RASMC), Rho kinase stimulated by angiotensin II was suppressed by the pretreatment with pioglitazone and troglitazone, and these effects were explained by the inhibition of the Rho translocation to the cell membrane. We evaluated the role of Vav, a GTP/GDP exchange factor upregulating Rho kinase activity, and Src homology region 2-containing protein tyrosine phosphatase-2 (SHP-2), a protein tyrosine phosphatase that dephosphorylated Vav and subsequently inactivated Rho kinase. Both pioglitazone and troglitazone upregulated SHP-2, particularly in the cytosolic fraction, and the SHP-2-bound Vav, and reduced the phosphorylation of Vav. Furthermore, 4-week treatment with pioglitazone lowered systolic blood pressure in spontaneously hypertensive rats (SHR) and suppressed the Rho/Rho kinase activity in aortic tissues isolated from SHR. Consistently, the expression of SHP-2 was upregulated in vascular tissues from pioglitazone-treated SHR. The phosphorylated Vav was increased in SHR, compared with that in normotensive Wistar-Kyoto rats (WKY), which was mitigated by pioglitazone. Finally, both basal and angiotensin II-stimulated levels of Rho kinase activity were greater in RASMC from SHR than those from WKY, and the enhanced Rho kinase activity was blocked by pioglitazone or troglitazone in both strains. Collectively, PPARgamma ligands inhibit the Rho/Rho kinase pathway through upregulation of cytosolic SHP-2 expression and inactivation of Vav, and may contribute to the hemodynamic, in addition to metabolic, action in hypertensive metabolic syndrome. The full text of this article is available online at http://circres.ahajournals.org.     

C-type natriuretic peptide ameliorates monocrotaline-induced pulmonary hypertension in rats

C-type natriuretic peptide (CNP) has been shown to act as a local regulator of vascular tone and remodeling. We investigated whether CNP ameliorates monocrotaline (MCT)-induced pulmonary hypertension in rats. Rats received a continuous infusion of CNP or placebo. Significant pulmonary hypertension developed 3 weeks after MCT. However, infusion of CNP significantly attenuated the development of pulmonary hypertension and vascular remodeling. Neither systemic arterial pressure nor heart rate was altered. Interestingly, CNP enhanced Ki-67 expression, a marker for cell proliferation, in pulmonary endothelial cells and augmented lung tissue content of endothelial nitric oxide synthase. CNP significantly suppressed apoptosis of pulmonary endothelial cells, decreased the number of monocytes/macrophages, and inhibited expression of plasminogen activator inhibitor type 1, a marker for fibrinolysis impairment, in the lung. In addition, CNP significantly increased the survival rate in MCT rats. Finally, infusion of CNP after the establishment of pulmonary hypertension also had beneficial effects on hemodynamics and survival. In conclusion, infusion of CNP ameliorated MCT-induced pulmonary hypertension and improved survival. These beneficial effects may be mediated by regeneration of pulmonary endothelium, inhibition of endothelial cell apoptosis, and prevention of monocyte/macrophage infiltration and fibrinolysis impairment.     

Serum–Glucocorticoid Regulated Kinase 1 Regulates Macrophage Recruitment and Activation Contributing to Monocrotaline-Induced Pulmonary Arterial Hypertension

Sustained inflammation is associated with pulmonary vascular remodeling and arterial hypertension (PAH). Serum–glucocorticoid regulated kinase 1 (SGK1) has been shown to participate in vascular remodeling, but its role in inflammation-associated PAH remains unknown. In this study, the importance of SGK1 expression and activation was investigated on monocrotaline (MCT)-induced PAH, an inflammation-associated experimental model of PAH used in mice and rats. The expression of SGK1 in the lungs of rats with MCT-induced PAH was significantly increased. Furthermore, SGK1 knockout mice were resistant to MCT-induced PAH and showed less elevation of right ventricular systolic pressure and right ventricular hypertrophy and showed reduced pulmonary vascular remodeling in response to MCT injection. Administering the SGK1 inhibitor, EMD638683, to rats also prevented the development of MCT-induced PAH. The expression of SGK1 was shown to take place primarily in alveolar macrophages. EMD638683 treatment suppressed macrophage infiltration and inhibited the proliferation of pulmonary arterial smooth muscle cells (PASMCs) in the lungs of rats with MCT-induced PAH. Co-culture of bone marrow-derived macrophages (BMDMs) from wild-type (WT) mice promoted proliferation of PASMC in vitro, whereas BMDMs from either SGK1 knockout mice or WT mice with EMD638683 treatment failed to induce this response. Collectively, the present results demonstrated that SGK1 is important to the regulation of macrophage activation that contributes to the development of PAH; thus, SGK1 may be a potential therapeutic target for the treatment of PAH.     

槲皮素对野百合碱诱导的大鼠肺动脉高压的影响

目的:观察槲皮素对野百合碱(MCT)诱导的肺动脉高压大鼠的治疗效果。方法:30只成年雄性SD大鼠随机分成3组:MCT诱导的肺动脉高压组(MCT组)、治疗组和对照组。MCT组和治疗组一次性皮下注射MCT 50mg/kg,饲养21d;对照组一次性皮下注射等量0.9%氯化钠溶液,饲养21d。造模后治疗组以槲皮素100mg.kg-1.d-1灌胃20d;MCT组和对照组以0.9%氯化钠溶液2ml/d灌胃20d。20d后,测定3组大鼠平均肺动脉压(mPAP),计算右心室肥大指数(RVHI);光镜下观察大鼠肺组织形态学的改变及肺血管增殖细胞核抗原(PCNA)增殖度的变化,并计算肺中、小动脉管壁厚度占血管外径的百分比(WT%)和肺动脉管壁面积/管总面积的百分比(WA%)。结果:MCT组的mPAP、RVHI、肺中、小动脉WT%、WA%及PCNA增殖度均显著高于对照组及治疗组。结论:槲皮素可降低MCT所致的大鼠肺血管PCNA表达,抑制MCT诱导的肺部炎症、肺血管重建和肺动脉高压形成,对MCT所致的大鼠肺动脉高压具有治疗作用。     

Chronic sildenafil treatment inhibits monocrotaline-induced pulmonary hypertension in rats

Sildenafil, a phosphodiesterase 5 inhibitor, is currently under investigation for therapy of pulmonary hypertension. This study was designed to investigate chronic effects of sildenafil in monocrotaline (MCT)-induced pulmonary hypertension in rats. Four weeks after a single subcutaneous injection of MCT, the animals displayed nearly threefold elevated pulmonary artery pressure and vascular resistance values, with a concomitant decline in central venous oxygen saturation and arterial oxygenation. Marked right heart hypertrophy was evident, and massive thickening of the precapillary artery smooth muscle layer was histologically apparent. Further deterioration of pulmonary hypertension occurred 6 weeks after MCT injection, with some animals dying during this period because of right heart failure. When chronically administered from Days 14-28, sildenafil significantly increased plasma cyclic guanosine monophosphate and inhibited the development of pulmonary hypertension and right heart hypertrophy, with preservation of gas exchange and systemic arterial pressure. A corresponding efficacy profile was also noted for long-term feeding with sildenafil from Days 28-42. Moreover, the death rate significantly decreased in those animals treated with sildenafil. We conclude that sildenafil attenuates MCT-induced pulmonary hypertension and cor pulmonale in rats.     

Genistein, a phytoestrogen, attenuates monocrotaline-induced pulmonary hypertension

BACKGROUND: Pulmonary hypertension is characterized by high pulmonary blood pressure, vascular remodeling, and right ventricular hypertrophy. Although recent studies suggest that an imbalance between endothelial mediators on pulmonary vasculature may contribute to the development of pulmonary hypertension, the pathogenesis is not fully understood and the treatment of pulmonary hypertension is still unresolved. OBJECTIVE: The purpose of this study was to investigate whether genistein, a phytoestrogen derived from soybean, would prevent the development of monocrotaline (MCT)-induced pulmonary hypertension in rats. Hemodynamic parameters of catheterized rats and morphological feature of lungs were evaluated among MCT-treated rats receiving or not receiving genistein. Furthermore, examination of expression in endothelial nitric oxide synthase and endothelin-1 peptide level was performed. METHODS: Daily supplementation with either genistein (0.2 mg/kg) or vehicle was started 2 days prior to a single-dose injection of MCT (60 mg/kg). On day 28, rats underwent catheterization, and right ventricular hypertrophy and morphological features were assessed. Furthermore, endothelial nitric oxide synthase and endothelin-1 were examined by Western blot analysis and radioimmunoassay, respectively, in homogenated lungs. RESULTS: In rats that received daily supplementation of genistein, mean pulmonary arterial pressure was significantly reduced, whereas mean systemic arterial pressure and heart rate were unaltered compared with MCT control rats on day 28 after MCT injection. Right ventricular hypertrophy, medial wall thickness of pulmonary arteries corresponding to the terminal bronchioles, and the degree of neo-muscularization of more distal arteries were less severe in genistein-treated rats. Genistein supplementation improved MCT-induced downregulation of expression of endothelial nitric oxide synthase in the lungs. However, endothelin-1 peptide levels did not differ among all groups of lungs. CONCLUSIONS: We conclude that daily supplementation of genistein potently attenuates MCT-induced pulmonary hypertension, right ventricular hypertrophy, and pulmonary vascular remodeling in rats. The underlying mechanism responsible for this effect may be partly related to the restoration of a decreased expression of endothelial nitric oxide synthase.     

Inhaled iloprost reverses vascular remodeling in chronic experimental pulmonary hypertension

RATIONALE: Inhaled iloprost is an effective therapy for pulmonary arterial hypertension (PAH). However, no study to date has addressed the effects of inhaled iloprost on changes to pulmonary vascular structure that occur in PAH. OBJECTIVES: The present study was designed to investigate chronic antiremodeling effects of inhaled iloprost in monocrotaline (MCT)-induced PAH in rats. Methods: Four weeks after a single injection of MCT, after full establishment of PAH, rats were nebulized with iloprost at a dose of 6 microg . kg(-1) . day(-1), or underwent sham nebulization with saline. RESULTS: After 2 weeks of inhalation therapy, right ventricular pressure and pulmonary vascular resistance were reversed in rats treated with iloprost, but not in sham-treated control animals. Systemic arterial pressure was unaffected. In addition, right heart hypertrophy, the degree of pulmonary artery muscularization, and the medial wall thickness of intraacinar pulmonary arteries regressed in response to iloprost. Furthermore, the MCT-induced increase in matrix metalloproteinase-2 and -9 activities and tenascin-C expression was suppressed. CONCLUSIONS: We conclude that the inhalation of iloprost reverses PAH and vascular structural remodeling in MCT-treated rats. This regimen suggests the possibility of an antiremodeling therapy in PAH.     

Pivotal role of peroxisome proliferator-activated receptor gamma (PPARgamma) in regulation of erythroid progenitor cell proliferation and differentiation

OBJECTIVE: The aim of this study was to reveal the role of peroxisome proliferator-activated receptor gamma (PPARgamma) in erythropoiesis. METHODS: The effects of PPARgamma ligands on cellular proliferation and differentiation were investigated in erythroid colony-forming cells (ECFCs) purified from human peripheral blood. RESULTS: RT-PCR analysis revealed that PPARgamma mRNA is expressed in ECFCs. Synthetic PPARgamma ligands, troglitazone or pioglitazone, suppressed cellular proliferation without inducing apoptosis and delayed maturation of ECFCs, as determined by flow cytometry. The delay in erythroid maturation by troglitazone was confirmed by the down-regulation of gamma-globin, beta-globin and GATA-1 mRNA, and the maintenance of GATA-2 mRNA. CONCLUSIONS: Our results suggest that PPARgamma modulates the differentiation process of erythroid progenitor cells, and plays a crucial role in regulating the balance of hematopoiesis.     

血管内皮生长因子在肺动脉平滑肌细胞重构中的作用

目的 :探讨血管内皮生长因子 （VEGF）在野百合碱 （MCT）性肺动脉高压 （PH）中的作用。方法 :用 MCT复制大鼠慢性 PH病理模型 ,用免疫组化法和图像分析技术测定肺组织中 VEGF的表达。结果 :发现 VEGF可在正常大鼠肺血管平滑肌、支气管平滑肌和软骨组织中表达 ,并且 MCT组 VEGF表达的相对含量在肺血管平滑肌 （177±7）和支气管平滑肌 （172± 6）均较正常组 （血管平滑肌 13 6± 8,支气管平滑肌 13 8± 12 ）呈显著增强 （P<0 .0 5）。结论 :MCT性 PH中 VEGF在肺血管平滑肌的过度表达参与 MCT性 PH的发病过程     

粒细胞集落刺激因子对大鼠肺动脉高压模型的影响

目的:探讨粒细胞集落刺激因子(G-CSF)对野百合碱(MCT)诱导的大鼠肺动脉高压(PAH)的治疗作用。方法:动物随机分为3组:正常对照组(CON组)、MCT组和MCT/G-CSF组,腹腔注射MCT诱导大鼠PAH模型,采用G-CSF腹腔注射动员自体骨髓干细胞(BMSC),动员结束后行肺组织CD34免疫组化染色,第5周分别对3组大鼠进行血流动力学检测,处死大鼠,取肺、右心组织行苏木素-伊红(HE)染色。结果:1.动员结束后第2天,CD34+细胞浸润至肺血管平滑肌层和血管内皮细胞周围,以及肺泡间隔内;2.实验第35天,MCT组大鼠肺小动脉管壁增厚、管腔明显狭窄,血流动力学指标明显高于CON组(P<0.01);3.MCT/G-CSF组肺血管病变明显改善、肺泡结构完整,血流动力学指标明显低于MCT组(P<0.05)。结论:G-CSF可以动员骨髓干细胞并归巢致受损肺组织内,部分逆转PAH的血流动力学和病理学改变、减缓PAH的进展,用于PAH的研究和治疗。     

PAF receptor blockade inhibits lung vascular changes in the rat monocrotaline model

We recently reported that platelet-activating factor (PAF) levels increased in lung tissue after 1 subcutaneous injection of monocrotaline (MCT) (which causes lung injury), and, further, that treatment with PAF antagonists reduced pulmonary hypertension in this chronic lung injury rat model [15]. In the present study, we examined the effect of WEB 2170, a specific PAF antagonist, on MCT-induced pulmonary vascular remodeling. At 3 weeks after MCT injection, pulmonary hypertension in the animals was associated with an increase in the vessel wall thickness of the muscular arteries, reduction in number of peripheral arterioles, and right ventricular hypertrophy. In WEB 2170-treated rats, these changes were significantly less severe when compared with those observed in MCT-treated rats. In MCT-treated rats, there were significant increases in in vitro [³H]thymidine incorporation and accumulation of hydroxyproline in the lung tissue, and these changes were inhibited by WEB 2170 treatment. Our results suggest that PAF or a PAF-dependent sequence of events is involved in MCT-induced lung vascular remodeling. Offprint requests to: N. F. Voelkel     

Combination of sildenafil and simvastatin ameliorates monocrotaline-induced pulmonary hypertension in rats

Sildenafil, a phosphodiesterase-5 inhibitor, and simvastatin, a cholesterol lowering drug, both have therapeutic effects on PAH; however, the combination of these drugs has not been tested in the treatment of PAH. The purpose of this study was to determine whether the combination of sildenafil and simvastatin is superior to each drug alone in the prevention of MCT-induced PAH. Phosphorylated Smad levels were decreased in lung tissue in MCT-injected rats, whereas ERK protein levels were increased. This indicates a possible role for an increase in mitogenic ERK activity in addition to decreased proapoptotic Smad signaling in the MCT model of PAH. Combination sildenafil and simvastatin treatment prevented the MCT-induced increases in right ventricular systolic pressure (RVSP) and right ventricular hypertrophy (RVH), exerted an anti-proliferative effect on pulmonary artery smooth muscle cells (PASMC). Our results indicate that combination therapy with sildenafil and simvastatin attenuated the development of pulmonary hypertension more than either treatment alone.     

Troglitazone inhibits formation of early atherosclerotic lesions in diabetic and nondiabetic low density lipoprotein receptor-deficient mice

Peroxisome proliferator-activated receptor-gamma (PPARgamma) is a ligand-activated nuclear receptor expressed in all of the major cell types found in atherosclerotic lesions: monocytes/macrophages, endothelial cells, and smooth muscle cells. In vitro, PPARgamma ligands inhibit cell proliferation and migration, 2 processes critical for vascular lesion formation. In contrast to these putative antiatherogenic activities, PPARgamma has been shown in vitro to upregulate the CD36 scavenger receptor, which could promote foam cell formation. Thus, it is unclear what impact PPARgamma activation will have on the development and progression of atherosclerosis. This issue is important because thiazolidinediones, which are ligands for PPARgamma, have recently been approved for the treatment of type 2 diabetes, a state of accelerated atherosclerosis. We report herein that the PPARgamma ligand, troglitazone, inhibited lesion formation in male low density lipoprotein receptor-deficient mice fed either a high-fat diet, which also induces type 2 diabetes, or a high-fructose diet. Troglitazone decreased the accumulation of macrophages in intimal xanthomas, consistent with our in vitro observation that troglitazone and another thiazolidinedione, rosiglitazone, inhibited monocyte chemoattractant protein-1-directed transendothelial migration of monocytes. Although troglitazone had some beneficial effects on metabolic risk factors (in particular, a reduction of insulin levels in the diabetic model), none of the systemic cardiovascular risk factors was consistently improved in either model. These observations suggest that the inhibition of early atherosclerotic lesion formation by troglitazone may result, at least in part, from direct effects of PPARgamma activation in the artery wall.     

Cilostazol therapy attenuates monocrotaline-induced pulmonary arterial hypertension in rat model.

BACKGROUND: Pulmonary arterial hypertension (PAH) is characterized by a progressive increase in pulmonary vascular resistance caused by a proliferation of vascular endothelial and smooth muscle cells, resulting in occlusion of the lumen of small pulmonary arteries. Cilostazol, with its antiproliferative effects on vascular endothelial and smooth muscle cells, may ameliorate monocrotaline (MCT)-induced PAH in rats. METHODS AND RESULTS: Male Sprague - Dawley rats (n=10/each group) were randomized to receive MCT (75 mg/kg) only (group 1), MCT plus cilostazol (20 mg .kg(-1 ). day(-1)) (group 2) and saline injection only (group 3). Hemodynamic measurement on day 28 following MCT treatment indicated the development of significant PAH on MCT-treated groups (p<0.0001). Cilostazol was given to group 2 orally on days 28-90. By day 90 following MCT treatment, the right ventricular (RV) systolic blood pressure and RV hypertrophy were significantly higher in group 1 than in groups 2 and 3 (all values of p<0.01). Additionally, connexin43 and endothelial nitric oxide synthase gene expressions of lung and RV, and Bcl-2 protein expression of RV, were significantly lower in group 1 than in groups 2 and 3 (all values of p<0.01). Furthermore, the number of alveolar sac and small arterioles of the lung were significantly lower in group 1 than in groups 2 and 3 (all values of p<0.01). CONCLUSION: Cilostazol therapy effectively attenuates of MCT-induced PAH.     

黄芩苷对肺动脉高压大鼠模型的治疗作用及可能的机制

目的:观察黄芩苷对野百合碱诱导的大鼠肺动脉高压模型的治疗作用和肺动脉平滑肌细胞凋亡的影响。方法:将48只大鼠随机分为正常对照组、模型组、辛伐他汀阳性对照组（辛伐他汀组）、3个黄芩苷剂量组（20 mg/kg、40 mg/kg、80 mg/kg,简称低、中、高黄岑苷组）,每组8只。通过皮下注射野百合碱诱导建立大鼠肺动脉高压模型,辛伐他汀组给予2 mg/kg灌胃,药物治疗组分别给予黄芩苷20、40、80 mg/kg灌胃。观察黄芩苷对肺动脉压、右室肥大指数的影响。将肺组织切片HE染色后,观察肺动脉的形态学变化。用免疫组化染色法检测肺血管平滑肌细胞中Bcl-2、Bax表达的变化。结果:与模型组比较,高、中黄芩苷可显著降低野百合碱所致大鼠的平均肺动脉压(P<0.01),高黄芩苷可降低其右室肥大指数(P<005);高、中黄岑苷可显著降低模型大鼠肺动脉中膜厚度比（P<0.01）和中膜面积比（P<0.01）;高、中黄芩苷可增加Bax的表达率（P<0.01）,降低Bcl-2的表达率（P<0.01）。结论:一定剂量的黄芩苷可有效降低野百合碱诱导的模型大鼠的肺动脉压,逆转肺动脉重构。黄芩苷可能是通过抑制肺动脉中膜平滑肌细胞增殖、促进其凋亡而发挥作用的。     

瑞舒伐他汀干预野百合碱诱导大鼠肺动脉高压的实验研究

目的 探讨他汀类药物改善内皮细胞功能、抗增殖等降脂外作用在防治肺动脉高压中的作用及可能机制.方法 雄性SD大鼠,体重(255.7±12.5)g,皮下注射野百合碱诱导大鼠形成肺动脉高压,肺动脉高压形成前后分别接受瑞舒伐他汀预防和治疗.预防实验:32只SD大鼠随机分为4组,分别为瑞舒伐他汀低剂量(2 mg·kg-1·d-1)预防组(n=8)、瑞舒伐他汀高剂量(10 mg·kg-1·d-1)预防组(n=8)、肺动脉高压4周组(n=8)和正常对照4周组(n=8),野百合碱注射当日起预防组每日予瑞舒伐他汀灌胃至第4周末,正常对照组、肺动脉高压4周组仅予生理盐水灌胃.治疗实验:52只SD大鼠随机分为4组,分别为瑞舒伐他汀低剂量(2 mg·kg-1·d-1)治疗组(n=12)、瑞舒伐他汀高剂量(10 mg·kg-1·d-1)治疗组(n=12)、肺动脉高压8周组(n=20)和正常对照8周组(n=8),野百合碱注射4周后治疗组每日予瑞舒伐他汀灌胃至第8周末,正常对照组、肺动脉高压8周组仅予生理盐水灌胃.比较各组生存率、平均肺动脉压(mPAP)、肺小动脉管壁厚度、右心室肥厚程度,比较肺小动脉增殖细胞核抗原(PCNA)、内皮型一氧化氮合酶(eNOS)蛋白表达水平,比较肺组织Rho激酶1(ROCK-1)、eNOS mRNA表达水平.结果 预防实验大鼠均存活,肺动脉高压形成之后瑞舒伐他汀治疗能改善生存率(瑞舒伐他汀低剂量治疗组、瑞舒伐他汀高剂量治疗组与肺动脉高压8周组比较为58%、75%比30%,P均＜0.05);肺动脉高压形成之前和之后瑞舒伐他汀预防和治疗均能降低mPAP[预防实验:瑞舒伐他汀低剂量预防组、瑞舒伐他汀高剂量预防组与肺动脉高压4周组比较为(27.53±3.43)mm Hg(1 mm Hg=0.133 kPa)、(25.72±1.76)mm Hg比(36.05±2.45)mm Hg,P均＜0.01;治疗实验:瑞舒伐他汀低剂量治疗组、瑞舒伐他汀高剂量治疗组与肺动脉高压8周组比较为(30.39±3.17)mm Hg、(27.59±1.99)mmHg比(40.68±1.39)mm Hg,P均＜0.01],减轻肺小动脉管壁增厚、右心室肥厚程度(P均＜0.01),下调肺小动脉平滑肌细胞PCNA表达(P均＜0.01),上调内皮细胞eNOS表达(P均＜0.05),抑制ROCK-1基因表达(P均＜0.05),有一定的剂量依赖性(P均＜0.05).结论 瑞舒伐他汀防治肺动脉高压可能是通过抑制ROCK-1基因表达,抑制肺动脉平滑肌增殖和恢复内皮细胞功能等机制来实现的.

Abstract：

Objective To investigate the effects of rosuvastatin on monocrotaline (MCT)-induced pulmonary artery hypertension in rats. Methods Pulmonary arterial hypertension was induced by a single subcutaneous injection of monocrotaline (50 mg/kg) in rats. In the prevention protocol, 32 male SpragueDawley rats were randomly divided into four groups ( n = 8 each): low-dose rosuvastatin prevention group (2 mg · kg-1 · d-1 ), high-dose rosuvastatin prevention group ( 10 mg· kg-1 · d-1 ), pulmonary arterial hypertension group, normal control group. Beginning on the MCT injection day, rats were treated with rosuvastatin by daily gavage for 4 weeks. Normal control group and pulmonary arterial hypertension group received vehicle by garage. In the treatment protocol, 52 male Sprague-Dawley rats were randomly dividedinto four groups (n = 13 each): low-dose rosuvastatin treatment group (2 mg · kg-1 · d-1), high-dose rosuvastatin treatment group( 10 mg · kg-1 · d-1), pulmonary arterial hypertension group, normal control group. Four weeks after MCT injection, rats were treated with rnsuvastatin by daily gavage for 4 weeks.Normal control group and pulmonary arterial hypertension group received vehicle by gavage. At the end of study, survival rates, mean pulmonary arterial pressure (mPAP), wall thickness of small pulmonary artery and right ventricular hypertrophy among groups were compared. The expression levels of proliferating cell nuclear antigen (P CNA) and endothelial nitricoxide synthase (eNOS) protein in small pulmonary artery,the expression levels of Rho kinase 1 ( ROCK-1 ) and eNOS mRNA in lung tissue were also detected. Results All rats in the prevention protocol survived. Rosuvastatin treatment improved survival in the treatment protocol (58%, 75% vs. 30%, P ＜0. 05 ). Rosuvastatin therapy in both preventment or treatment protocols significantly lowered mPAP [prevention protocol: ( 27.53 ± 3.43 ), ( 25.72 ± 1.76 ) vs. ( 36. 05 ± 2. 45 )mm Hg(1 mm Hg =0. 133 kPa), P ＜0.01; treatment protocol: (30. 39 ±3. 17), (27.59 ±1.99) vs.(40. 68 ± 1.39) mm Hg, P ＜0. 01], reduced thickening of small pulmonary artery wall (P ＜0. 01 ) and right ventricular hypertrophy ( P ＜ 0. 01 ). Rosuvastatin also inhibited PCNA expression of SMC ( P ＜0. 01 ), restored eNOS expression of EC ( P ＜ 0. 05) and inhibited ROCK-1 mRNA expressions in lung tissue (P ＜ 0. 05 ). Conclusions Rosuvastatin therapy reduced mPAP in monocrotaline-induced pulmonary arterial hypertension rat model and this effect is linked with inhibition of ROCK-I expression, inhibition of smooth muscle cell proliferation and restoration of endothelial cell functions.     

Polyamines and epidermal growth factor in monocrotaline-induced pulmonary hypertension

Multiple lines of evidence suggest that the polyamines, a family of low-molecular-weight organic cations with documented regulatory note in cell growth and differentiation, are involved with hyperplastic and hypertrophic responses of lung cells underlying hypertensive pulmonary vascular disease. Little is known, however, of the factor(s) initiating polyamine synthesis in pulmonary hypertension. This study tested the key aspects of the hypothesis that augmented polyamine synthesis, and attendent vascular structural alterations in monocrotaline (MCT)-treated rats can be ascribed to elaboration of an epidermal growth factor (EGF)-like mitogen. In lungs of rats treated 4 days previously with 60 mg/kg, EGF-like immunoreactivity was detected diffusely throughout perivascular regions. Intravenous administration of human recombinant EGF (125 pg/h) to rats for 1 wk was associated with medial thickening in pulmonary arteries between 100 and 200 microns in diameter, significant increases in lung polyamine contents, and a moderate elevation in mean pulmonary arterial pressure. These observations indicate that EGF can be detected in the lungs of MCT-treated rats and that exogenous EGF mimics some of the action of MCT on the rat lung. It is thus reasonable to speculate that an EGF-like mitogen may participate in the response to MCT in part through a polyamine-dependent mechanism.     

Troglitazone induces p27Kip1-associated cell-cycle arrest through down-regulating Skp2 in human hepatoma cells

Increasing evidence has confirmed that ligands for peroxisome proliferator-activated receptor gamma (PPARgamma) exhibit antitumoral effects through inhibition of cell proliferation and induction of cell differentiation in several malignant neoplasms. Recently, we have documented the accumulation of a cyclin-dependent kinase inhibitor, p27(Kip1), as well as an unexpected accumulation in cyclin E in G1-arrested human hepatoma cells treated with the PPARgamma ligand troglitazone. Simultaneous accumulations in both p27(Kip1) and cyclin E are known to be characteristic phenotypes in cells derived from mice lacking Skp2, an F-box protein component of the SCF ubiquitin-ligase complex. Thus, the aim of the present study was to assess whether Skp2 might be involved in the down-regulation of p27(Kip1) in troglitazone-treated human hepatoma cells. A striking decrease in Skp2 expression and a reciprocal increase in p27(Kip1) expression were found in troglitazone-treated hepatoma cells but not in those cells treated with other PPARgamma ligands such as pioglitazone and ciglitazone. Quantitative real-time RT-PCR analysis showed that troglitazone down-regulated Skp2 at the mRNA levels. Consistently, ectopic overexpression in Skp2 brought resistance to troglitazone, resulting in a decreased population of arrested cells at the G1 phase compared with that in the mock-transfected cells. In surgically resected hepatocellular carcinoma (HCC) tissue, an increased expression in Skp2 was found in both the moderately differentiated HCCs and the poorly differentiated HCCs. In conclusion, troglitazone attenuated Skp2 expression, thereby promoting p27(Kip1) accumulation in human hepatoma cells. This therapeutic potential of the ligand may lead to new cell-cycle-based antitumor strategies for advanced HCCs.