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.