强力霉素、氯沙坦及其合用对大鼠急性心肌梗塞后非梗塞区心肌金属蛋白酶和金属蛋白酶组织抑制因子表达及胶原重构的影响

Comparison of Doxycycline, Losartan, and Their Combination on the Expression of Matrix Metalloproteinase, Tissue Inhibitor of Matrix Metalloproteinase, and Collagen Remodeling in the Noninfarcted Myocardium after Acute Myocardial Infarction in Rat

目的对比基质金属蛋白酶(MMP)抑制剂强力霉素、血管紧张素Ⅱ受体-1阻断剂氯沙坦及其合用对急性心肌梗塞(AMI)大鼠左室非梗塞区心肌MMP-8和13、MMP组织抑制因子(TIMP)-1和2的表达及胶原重构影响。方法对431只雌性SD大鼠行冠状动脉前降支结扎致AMI,然后将术后24h存活的254只随机分入下列各组:(1)AMI对照组(n=64);(2)强力霉素组(30mg·kg-1·d-1,n=63);(3)氯沙坦组(10mg·kg-1·d-1,n=62);(4)强力霉素(30mg·kg-1·d-1)和氯沙坦(10mg·kg-1·d-1)合用组(n=65),并开始给药治疗;同时另设假手术组(n=30)。依疗程不同,将上述各组再均分为1、2和4周3个亚组。以RT-PCR和Westernblot法测定非梗塞区两种MMP和TIMP的mRNA和蛋白表达;免疫组织化学染色测定非梗塞区Ⅰ/Ⅲ型胶原含量(CVF)。结果AMI对照及3治疗组各亚组间梗塞面积差异均无显著性(P均>0.05)。与假手术组相比,AMI对照组的MMP-8和13蛋白表达在各时间亚组均显著增高(P均<0.05),mRNA表达则在1和4周亚组显著增高(P均<0.05);TIMP-1mRNA和蛋白表达仅在1周亚组显著增高(P均<0.05);TIMP-2mRNA表达在各时间点亚组均显著增高(P均<0.05),而蛋白表达仅在2和4周亚组均显著增高(P均<0.05);同时非梗塞区Ⅰ/Ⅲ型CVF在各时间亚组也均显著升高(P<0.05～0.001)。与AMI对照组相?

Objective To compare the effects of matrix metalloproteinase(MMP)inhibitor doxycy-cline, losartan, and their combination on the expression of MMP-8, 13, tissue inhibitor of MMP-1, 2(TIMP-1, 2), and collagen remodeling in the noninfarcted myocardium after acute myocardial infarction(AMI)in rats. Methods Two hundred and fifty-four AMI rats, induced by left coronary ligation, were randomly assigned to the following groups:(1)AMI controls group(n = 64);(2)doxycycline group(30 mg·kg-1·d-1, n = 63);(3)losartan group(10 mg·kg-1·d-1, n = 62);(4)concomitant doxycycline and losartan group(30 and 10 mg·kg-1·d-1 respectively, n = 65); and(5)Sham-operated rats(n = 30), which were randomly selected to serve as noninfarction controls. Each group was further divided into three subgroups of 1, 2, and 4 weeks that received treatment. After the completion of treatment, the rats were killed. The mRNA and protein expression of MMPs and TIMPs in the noninfarcted myocardium were quantified by RT-PCR and Western blot, respectively. The type Ⅰ and type Ⅲ collagen volume fraction(CVF)of the noninfarced myocardium were assessed immunohistochemically. Results No significant difference existed in myocardial infarction sizes among the 12 subgroups of AMI controls and the three treatment groups(42%-48%, all P > 0.05). Compared with sham operated rats, the mRNA and protein expression of MMP-8 and 13 significantly increased by 39%-183% in all three subgroups of AMI controls(all P < 0.05), except both of their mRNA expressions in 2-week subgroups; the mRNA and protein levels of TIMP-1 increased only in 1-week subgroup of AMI controls by 104% and 67%, respectively(both P < 0.05); the mRNA of TIMP-2 increased in all 1, 2, and 4-week subgroups by 144%-232%(all P < 0.05), but its protein expression lagged and only enhanced in 2 and 4-week subgroups of AMI controls by 231% and 332%, respectively(both P < 0.05). Meanwhile, both type Ⅰ and type Ⅲ CVF of noninfarcted myocardium significantly increased in all three subgroups of AMI controls(type Ⅰ CVF:3.01%-5.64% vs 1.53%-1.67%, P < 0.01-0.001; type Ⅲ CVF:2.19%-4.42% vs 1.46%-1.59%, P < 0.05-0.001), with type Ⅰ CVF being higher in 4-week than in 1 and 2-week subgroups(5.64% vs 3.01% and 3.02% respectively, all P < 0.05). Compared with AMI controls, all three kinds of treatment significantly reduced the increased mRNA and protein expressions of MMP-8, 13 and TIMP-1, 2 after AMI by 14%-60%(all P < 0.05), as well as type Ⅰ/Ⅲ CVF in their 2 and 4-week subgroups(type Ⅰ CVF:1.56%-2.38% vs 3.02%-5.64%, P < 0.05-0.001;type Ⅲ CVF:1.92%-2.65% vs 4.19%-4.42%, P < 0.05-0.01), except for doxycycline's effect on type Ⅲ CVF in any of its three subgroups(all P > 0.05). Among the three treatment groups, significant differences existed in the above mentioned indicators only at some subgroup levels(all P < 0.05). Conclusions Like losartan, doxycycline can also suppress the enhanced mRNA and protein expression of MMP-8, 13 and TIMP-1, 2, and reduce type Ⅰ collagen deposition in the noninfarcted myocardium after AMI in rats. However, it has no effect on type Ⅲ collagen deposition.