The Changes of Pulmonary Pathology and Gene Expressions in Monocrotaline-Induced Pulmonary Hypertension Rat Model after Simvastatin Treatment

Abstract

Background and Objectives: 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase inhibitor, simvastatin has several properties suggestive of a potential pathophysiologic role in pulmonary hypertension. Simvastatin caused apoptosis of lumen-obliterating cells, associated with a significant reduction of pulmonary artery pressure and right ventricular hypertrophy. The objectives of this study were to investigate changes of pulmonary pathology and gene expressions of endothelin (ET)-1, endothelin receptor A (ERA), inducible nitric oxide synthase (NOS2), endothelial nitric oxide synthase (NOS3), matrix metalloproteinase(MMP) 2, tissue inhibitor of matrix metalloproteinases (TIMP) and caspase 3 and to evaluate the effect of simvastatin on monocrotaline (M)-induced pulmonary hypertension. Materials and Methods: Six week old male Sprague-Dawley rats were treated as follows: control (n=18), subcutaneous (sc) injection of saline; M (n=36), sc injection of M(60 mg/kg); and simvastatin (n=36), sc injection of M(60 mg/kg) plus 10 mg/kg/day simvastatin orally. Results: Right ventricular hypertrophy (RVH) has significantly decreased in the simvastatin group than the M group on day 28. Right ventricular pressure increased in the M group from day 5 and has significantly decreased in the simvastatin group on day 28. Ratio of medial thickening of pulmonary artery was significantly increased from 7 day in M group but there was no significant change in simvastatin group. Number of muscular pulmonary arteriole was significantly reduced in simvastatin group. Gene expressions of ET-1, NOS3 and TIMP were significantly increased in the M group on day 5. Gene expressions of ERA and MMP were significantly increased in M group on day 1. Gene expression of NOS2 was significantly increased in M group on day 7. Gene expressions of ET-1, ERA, NOS2, NOS3, MMP and TIMP were significantly decreased in the simvastatin group on day 5. Triglyceride has significantly decreased in the simvastatin group on day 1 and day 14 but cholesterol had no change. Conclusions: Administration of simvastatin exerted weak inhibitory effects on RVH and number of muscular pulmonary arteriole during development of M-induced pulmonary hypertension in rats. Simvastatin decreased gene expressions on day 5. Further research is needed according to dosage of simvastatin to determine the effect of simvastatin on M induced pulmonary hypertension model. ;목적: simvastatin은 콜레스테롤을 감소시키는 작용 외에 세포 증식을 억제하고, 항혈전, 항염증, 항산화작용을 한다. 또한 폐동맥 압력을 감소시키고 우심실 비대를 감소시킨다는 보고가 있지만 저자들마다 다른 결과를 보고하고 있다. 이 연구의 목적은 monocrotaline(M)으로 유발된 폐동맥 고혈압 백서 모델에서 simvastatin 투여 후 폐동맥의 해부학적 변화와 7개 유전자[endothelin-1(ET), endothelin receptor A(ERA), inducible nitric oxide synthase(NOS2), endothelial nitric oxide synthase(NOS3), matrix metalloproteinase 2(MMP2), tissue inhibitor of matrix metalloproteinase(TIMP), caspase 3] 발현의 변화를 연구하고자 하였다. 대상 및 방법: 생후 6주된 Sprague-Dawley 쥐를 대조군(생리 식염수), M군(60mg/kg, 피하주사), simvastatin군(M 60mg/kg + simvastatin 10mg/kg/day) 세군으로 나누어 실험하였다. 우심실 압력, 우심실 무게, 우심실/좌심실+중격 비를 측정하였고, 1, 5, 7, 14, 28일에 쥐를 희생시켰다. H-E 염색을 하여 폐동맥 중막 비후율과 근육성 폐세동맥 수를 측정하였다. RT-PCR을 시행하여 simvastatin 투여 후에 ET-1, ERA, NOS2, NOS3, MMP2, TIMP, caspase3 유전자 발현의 변화를 관찰하였다. 결과: simvastatin 투여 후 28일에 우심실 무게, 우심실/좌심실+중격 비가 M 군에 비해 유의하게 감소되었다. 우심실 압력은 M 군에서 5일째부터 증가하기 시작하였고, simvastatin 투여 후 28일에 M 군에 비해 유의하게 감소하였다. 폐동맥 중막 비후율은 M 군에서 7일째부터 대조군에 비해 유의하게 증가하였으나 simvastatin 투여 후 유의한 감소는 없었다. 근육성 폐세동맥의 수는 M 군에서 7일째부터 유의하게 증가하였고, 7, 14, 28일에 simvastatin 군에서 M 군에 비해 유의하게 감소하였다. MCT 군에서 대조군에 비해서 유의하게 증가된 유전자 발현은Simvastatin 투여 5일째 7개의 유전자 발현이 M군에 비해 유의하게 감소하였다. Simvastatin 투여 후 1일, 14일째 중성지방이 MCT군에 비해 유의하게 감소하였으나, 콜레스테롤은 유의한 차이가 없었다. 결론: Simvastatin 투여는 우심실 비대, 근육성 폐동맥 수를 감소시켰으나 지속적인 폐동맥 고혈압 치료에는 효과가 적을 것 같다. 유전자 발현도 simvastatin 투여 5일째 M군에 비해 유의하게 감소하였으나, 유전자 발현에 대해서는 simvastatin 용량을 달리하여 추후에 더 많은 연구가 필요할 것으로 생각된다.