Objective To investigate the effects of simvastatin on monocrotaline-induced pulmonary hypertension in rats, and explore the potential mechanism of simvastatin by blocking heme oxygenase-1( HO-1) expression. Methods 52 male Sprague-Dawley rats were randomly divided into five groups, ie. a control group, a simvastatin control group, a pulmonary hypertension model group, a simvastatin treatment group, a ZnPP ( chemical inhibitor of HO) group. Mean pulmonary arterial pressure ( mPAP) and right ventricular systolic pressure ( RVSP) were detected by right heart catheter at 5th week. Right ventricular hypertrophy index ( RVHI) was calculated as the right ventricle to the left ventricle plus septum weight. Histopathology changes of small intrapulmonary arteries were evaluated via image analysis system.Immunohistochemical analysis was used to investigate the expression and location of HO-1. HO-1 protein level in lung tissue were determined by western blot. Results Compared with the model group, simvastatin treatment decreased mPAP and RVHI significantly [ ( 35. 63 ±5. 10) mm Hg vs. ( 65. 78 ±15. 51) mm Hg,0. 33 ±0. 05 vs. 0. 53 ±0. 06, both P lt; 0. 05 ] . Moreover, simvastatin treatment partially reversed the increase of arterial wall area and arterial wall diameter [ ( 50. 78 ±9. 03 ) % vs. ( 65. 92 ±7. 19) % ,( 43. 75 ±4. 23) % vs. ( 52. 00 ±5. 35) % , both P lt; 0. 01) . In the model group, HO-1 staining was primarily detected in alveolar macrophages. Simvastatin treatment increased HO-1 protein expression significantly, especially in the thickened smooth muscle layer and alveolar macrophages. Inhibiting HO-1 expression using ZnPP resulted in a loss of the effects of simvastatin. mPAP in the ZnPP group was ( 52. 88±17. 45) mm Hg, while arterial wall area and arterial wall diameter were ( 50. 78 ±9. 03) % and ( 52. 00 ±5. 35) % , respectively. Conclusions Simvastatin attenuates established pulmonary arterial hypertension andpulmonary artery remodeling in monocrotaline-induced pulmonary hypertension rats. The effect of simvastatin is associated with HO-1.
Objective To investigative the effects of combination treatment with simvastatin and aspirin in a rat model of monocrotaline-induced pulmonary hypertension. Methods Sixty male Sprague-Dawley rats were randomly divided into a control group, a simvastatin group, an aspirin group, and a combination treatment group. The control group received monocrotaline injection subcutaneously to induce pulmonary hypertension. Simvastatin ( 2 mg/kg) , aspirin ( 1 mg/kg) , or simvastatin ( 2 mg/kg) + aspirin ( 1 mg/kg) was administered once daily to the rats of treatment groups respectively for 28 days after monocrotaline injection. Mean pulmonary arterial pressure ( mPAP) was detected by right heart catheter.Right ventricular hypertrophy index ( RVHI) was calculated as the right ventricle to the left ventricle plus septum weight. Histopathology changes of small intrapulmonary arteries were evaluated via image analysissystem. Interleukin-6 ( IL-6) level in lung tissue was determined by ELISA.Results Compared with the control group, simvastatin or aspirin decreased mPAP [ ( 34. 1 ±8. 4) mm Hg, ( 38. 3 ±7. 1) mmHg vs.( 48. 4 ±7. 8) mmHg] and increased arterial wall diameter significantly ( P lt; 0. 05) . The combination treatment group showed more significant improvement in mPAP, RVHI and pulmonary arterial remodeling compared with each monotherapy ( P lt;0. 05) . Moreover, the combination therapy had additive effects on the increases in lung IL-6 levels and the perivascular inflammation score. Conclusions Combination therapy with simvastatin and aspirin is superior in preventing the development of pulmonary hypertension. The additive effect of combination therapy is suggested to be ascribed to anti-inflammation effects.
Abstract： Objective To study the effect of different numbers of bone marrow mesenchymal stem cells（MSCs） transplanted into rats with pulmonary arterial hypertension （PAH）induced by monocrotaline（MCT）and their influence on the expression of endothelin-1（ET-1）. Methods Forty healthy male Wistar rats（weight，from 180 to 250 g） were divided into four groups by random number table（n=10）：group A：Wistar rats were intraperitoneally injected with MCT 60 mg/ kg， and then injected with 1×106 MSCs via the external jugular vein；group B：Wistar rats were intraperitoneally injected with MCT 60 mg/kg，and then injected with 5×105 MSCs via the external jugular vein；MCT group：Wistar rats were intraperitoneally injected with MCT 60 mg/kg， and then injected with equal amount of PBS via the external jugular vein； control group：Wistar rats were intraperitoneally injected with equal amount of saline and then injected with equal amount of PBS via the external jugular vein. Four weeks after MSCs transplantation，right ventricular systolic pressure（RVSP） and ventricular weight ratio of right ventricle/ （left ventricle＋ventricular septum）were measured. Histomorphology of lung tissue was observed. Genetic expression of ET-1 in lungs and serum peptide of ET-1 were also measured. Results Four weeks after MSCs transplantation，both RVSP and ventricular weight ratio decreased significantly in rats of group Acompared with those of MCT group（RVSP：35.8±4.2 mm Hg vs. 47.2±10.1 mm Hg，P＜ 0.01； ventricular weight ratio：0.357±0.032 vs. 0.452±0.056，P＜0.01）， but these two parameters didn’t decrease significantly in rats of group B（P＞ 0.05）. By histopathological staining， the percentage of medial wall thickness of the pulmonary arterioles was significantly less in rats of group A than that of MCT group（19.7%±3.0% vs. 26.8%±3.6%， P＜ 0.01）. There was no statistical difference in the percentage of medial wall thickness of the pulmonary arterioles between group B and MCT group. Reverse transcriptase-polymerase chain reaction （RTase-PCR）results showed that ET-1messenger ribonucleic acid（mRNA）expression was highest in MCT group and MSCs transplantation significantly decreasedits expression in group A， while its expression was similar between group B and MCT group. The expression ofET-1 in plasma was also significantly decreased in group A than that in MCT group. Conclusion Intravenous MSCs transplantation can significantly inhibit MCT-induced PAH，and reduce both ET-1 mRNA expression in lung and ET-1 peptide level in plasma. It’s a better choice to transplant 1×106 MSCs to inhibit PAH in rats.
Abstract: Objective To build a rat model of right ventricular failure （RVF） by subcutaneous injection of Monocrotaline. Methods Forty Wistar rats were equally divided into four groups, 10 rats each group. Exp4 group: four weeks after Monocrotaline injection, experimental results were observed; Exp6 group: six weeks after Monocrotaline injection, experimental results were observed; Con4 group: four weeks after normal saline injection, experimental results were observed; Con6 group: six weeks after normal saline injection, experimental results were observed. Four and six weeks after Monocrotaline or normal saline injection respectively, the hemodynamic indexes of each pair of groups were measured. Their hearts and livers were excised to measure physiological indexes and had pathological examinations. Results Mean pulmonary arterial pressure (MPAP), maximal rate of change of right ventricular pressure (RV dp/dtmax) and right ventricular ypertrophy index in Exp4 group were higher than those in Con4 group（Plt;0.05,0.01）. Compared with Con6 group, there were obvious symptoms of RVF in Exp6 group which included the increases of heart rate, increases of central venous pressure (CVP) and MPAP, the decreases of RV dp/dtmax, the decreases of weight, the increases of liver weight/body weight ratio and right ventricular hypertrophy index, significant pleural and peritoneal effusions（P＜0.05,0.01 ）. Pathological examination of Exp6 group showed disordering and bifurcated cardiac muscle fibers, large and thickly dying cell core, enlarged transverse diameter of the cardiac muscle fibers and stroma fibrosis. Vacuolar degeneration and dissolved carcoplasm could be seen. The vessel wall of the lung arteriole thickened, intercellular layer smooth muscle cell hyperplasied, elastic fibers increased, vessel wall arteriosclerosised, lumens stenosized. Conclusion This model is simple to build and successful rate is high. It is valuable for further research.
ObjectiveTo observe the pathological changes in heart and lung tissues in rats with pulmonary hypertension induced by monocrotaline. MethodsTwenty-four male Sprague-Dawley rats were randomly and equally divided into an experimental group and a control group. The rats in the experimental group were intraperitoneally injected with monocrotaline to induce pulmonary hypertension, and the rats in the control group were treated with saline. All rats were fed for 3 weeks, and the general situation were observed. Then the rats were sacrificed for measurement of mean pulmonary artery pressure (mPAP), right ventricular hypertrophy index [RV/(LV+S)], changes of myocardial cells and lung vascular, calculated density of middle membrane smooth muscle cells (SMC) in medium/small pulmonary arteries accompanied with bronchi and alveoli, media thickness of pulmonary artery (PAMT), the percentage of wall thickness with outer diameter (WT%), the percentage of wall area with total area (WA%), the average diameter of myocardial cells (AD), and myocardial nuclei density (MND). ResultsCompared with the control group, the condition of rats in the experimental group were getting worse obviously.mPAP and RV/(LV+S) were both increased (both P < 0.05). The observation by light microscope revealed that obvious myocardial hypertrophy and structure disturbances, severe luminal stenosis of medium/small pulmonary arteries, medial thickening, infiltration of inflammatory cell in tissue space, proliferation of unorganized collagen fibers in the experimental group. The observation by electronic microscope showed proliferation of endothelial cell with irregular nuclei, increased organelles and vacuoles in the experimental group. The differences in SMC, PAMT, WT%, WA%, AD, and MND were significant between two groups (all P < 0.05). ConclusionsThe monocrotaline can induced pulmonary hypertension and right ventricular hypertrophy. The mechanism may be related to severe stenosis or occlusion of the vessel lumen caused by plexiform proliferation of endothelial cells, proliferation of smooth muscle cells and collagen fibers, compensatory hypertrophy and hyperplasia of myocardial cells.
Objective To observe the protective effects of simvastatin at different stages on monocrotaline (MCT) induced pulmonary arteral hypertension (PAH) in rats and evaluate the early preventive effect of simvastatin. Methods Twenty-four male SD rats were randomized into a control group, a PAH group, an early intervention group, and a late intervention group, with 6 rats in each group. The rats in the control group received intraperitoneal injection of normal saline (NS) on d0. The rats in the PAH group received one-off intraperitoneal injection of MCT (50 mg/kg) on d0. The rats in the early intervention group were pretreated with oral gavage of simvastatin (20 mg·kg–1·d–1)(d–7––1) before the intraperitoneal one-off injection of MCT (50 mg/kg, d0) and continued with oral gavage of simvastatin for 14 days (d1~14). The rats in the late intervention group received one-off intraperitoneal injection of MCT (50 mg/kg)(d0) and oral gavage of simvastatin (20 mg·kg–1·d–1) for the next 21 days (d15~35). Thirty-five days after the MCT injection (d36), mean pulmonary arterial pressure (mPAP) and right ventricular systolic pressure (RVSP) were measured by right heart catheter. Then the rats were sacrificed for separating the heart and lung, the right ventricular hypertrophy index (RVHI) and percentage of small pulmonary arteries media thickness (WT%), the inflammation score around the small pulmonary arterial were recorded. Results Compared with those in the PAH group, RVSP, mPAP, RVHI and WT% in two simvastatin interventiongroups got much better (P＜0.01), and the inflammation score around the small pulmonary arterial declined (P＜0.05). Compared with those in the late intervention group, RVSP, mPAP in the early intervention group improved (P＜0.05) and WT% decreased more significantly (P＜0.01). However RVHI and the inflammation score around the small pulmonary arterial were not different between two simvastatin intervention groups. Conclusions Both early intervention and late intervention with simvastatin can reduce RVSP, mPAP and WT% in MCT induced PAH rats. Compared with later intervention, early intervention can prevent PAH more remarkably.