普伐他汀对家兔血小板源一氧化氮系统影响的实验研究

The effects of pravastatin on platelet-derived nitric oxide system in rabbits

目的动态观察普伐他汀治疗前后血小板源一氧化氮(NO)系统的变化及其与动脉粥样硬化(atherosclerosis,AS)进程的关系.方法高胆固醇饲养诱导AS新西兰白兔模型30只.设普伐他汀药物干预组(A组,0周时开始服用普伐他汀10 mg/d至24周)、普伐他汀药物治疗组(B组,在高胆固醇饲养(12周时开始服用普伐他汀10 mg/d至24周)、无药物对照组(C组,0～24周均不用药).采用RT-PCR方法检测A、B、C三组在0,6,12,18,24周不同时间血小板源内皮型氧化氮合酶(eNOS)基因mRNA和诱导型氧化氮合酶(iNOS)基因mRNA表达、氧化氮合酶(NOS)活性及NO含量的变化;通过大体病理形态证实不同时间大动脉AS程度及斑块形成情况.结果血小板源eNOSmRNA在0,6,12,18,24周时的表达量:A组无明显改变;B组分别是0.95±0.77,0.53±0.33,0.49±0.25,0.83±0.28,1.00±0.77(P＜0.05);C组分别是0.82±0.16,0.40±0.29,0.33±0.29,0.51±0.23,0.19±0.12(P＜0.05).6,12周时B组和C组与A组比较明显降低(P＜0.05);18,24周时,B组与A组无明显差异,但A组和B组较C组明显增高(P＜0.01).iNOS mRNA表达在A、B、C三组不同时期均无变化.NOS活性及NO含量在三组不同时期变化与eNOS mRNA相似.大体形态:A组未见AS形成;B组12周时见大动脉内膜粗糙,有大量脂纹,24周时有部分大动脉仍有脂纹,但内膜较光滑,未见斑块;C组24周时各大动脉均见大量斑块或脂纹.结论随着高胆固醇血症(HC)及AS的形成,血小板源eNOS mRNA表达量、NOS活性及NO含量逐渐降低;普伐他汀能上调血小板源eNOSmRNA表达,提高NOS活性,并能稳定AS病变的继续发展或使其逆转.

Objective To observe the effects of pravastatin on platelet-derived nitric oxide system in hypercholesterolemia （HC） and atherosclerosis（AS） in rabbits, and the relationship between these changes and atherosclerosis courses. Methods Thirty male New Zealand white rabbits were randomly divided into three groups,12 in group A,12 in group B,and 6 in group C. All of them were fed daily with cholesterol-rich food during the first 12 weeks. In addition, in group A, pravastatin （10 rag） was orally administered daily. At the end of the 12^th week, 6 in group A and B were killed randomly and their aortas were removed and the pathologic changes were observed. In the following 12 weeks, food enriched with cholesterol was substituted with normal food in all three groups. Pravastatin treatment was continued or started in the remaining members of group A and group B, but not in group C. At the end 24^th week, all rabbits were killed and their aortas were examined for the fatty-streaks or atherosclerotic plaques. The expressions of endothelial NOS （eNOS） mRNA and inducible NOS（iNOS ） mRNA, NOS activity, NO production and the level of the serum lipids were measured at 0, 6^th, 12^th, 18^th and 24^th week. Results The expression levels of platelet-derived NOS mRNA. eNOS mRNA ratio in group A had no difference at above time points, while in group B were reduced significantly at 6^th week and 12^th week compared with at 0 week （ P 〈0.01 ） , and increased at 18^th week and 24^th week compared with 12^th week （ P 〈 0.05 ）. The expression levels of eNOS mRNA in group C were reduced at 6^th, 12^th and 18^th ,24^th week compared with 0 week （ P 〈0.05 and P 〈0.01 , respectively）, and were reduced in groups B and C compared with group A at 6^th, 12^th week （ P 〈 0.05） and increased in group Aand B compared with group C at 18^th, 24^th week （P 〈0.01 ）. The expression levels of iNOS/mRNA among the three groups had no difference. Pathologic finding of the arteries： AS was not found in group A from the 12^th to 24^th week. While in group B, there were a lot of fatty-streaks on the entire intima of all large arteries at the 12^th week. There were also fatty-streaks in the ascending aorta, but were improved at the 24^th week. In group C, there were marked plaques in the entire aorta at the 24^th week. Conclusions The expressions of platelet-derived eNOS mRNA, NOS activity, NO production are decreased in HC or AS rabbits. Pravastatin can up-regulate expressions of platelet-derived eNOS mRNA, NOS activity, leading to preventing or improving the pathological courses of AS.