雷帕霉素逆转大鼠肺动脉高压的作用机制研究

Mechanisms for reversal of pulmonary hypertension by rapamycin in rats

摘要:

目的 探讨雷帕霉素(RAP)对大鼠肺动脉高压的作用,为临床药物治疗肺动脉高压的选择提供新思路。方法 将健康雄性Sprague-Dawley 大鼠50 只随机分为空白对照组、模型组、溶剂对照组、RAP 干预1 组(术后5 d 开始干预)和RAP 干预2 组(术后35 d 开始干预)。左肺切除(PE)联合野百合碱(MCT)诱导肺动脉高压大鼠模型;造模后5 d 分别给予溶剂对照组溶媒和RAP 干预1 组RAP 肌肉注射;造模后35 d 给予RAP 干预2 组RAP 肌肉注射。测定各组平均肺动脉压(mPAP)和RV/(LV+S)比值。苏木精-伊红染色观察各组右肺组织病理学改变。Real-time PCR 测定各组平滑肌α 肌动蛋白(α-SMA)及平滑肌22α 蛋白(SM22α)mRNA 的相对表达量。结果 模型组及溶剂对照组大鼠术后35 d mPAP 明显高于空白对照组,RAP 干预1 组及RAP 干预2 组大鼠的mPAP 明显低于溶剂对照组(P<0.05);模型组及溶剂对照组大鼠RV/(LV+S)明显高于空白对照组,RAP 干预1 组大鼠RV/(LV+S)低于溶剂对照组(P<0.05),而RAP 干预2 组大鼠RV/(LV+S)与溶剂对照组比较差异无统计学意义(P>0.05);右肺病理组织学HE 染色可见模型组及溶剂对照组的肺动脉壁较空白对照组明显增厚,管腔狭窄,RAP 干预后可见增厚肺动脉壁有不同程度逆转;Real-time PCR 结果显示,模型组及溶剂对照组SM22α 及α-SMA 基因相对表达量明显低于空白对照组,RAP 干预1 组及RAP 干预2 组的SM22α 及α-SMA 相对表达量高于溶剂对照组(P<0.05)。结论 RAP 可逆转肺动脉压力的升高及右心室肥厚程度,其作用机制可能为通过调节血管平滑肌细胞表型转换而实现。

Abstract:

Objective To investigate the effects of rapamycin (RAP) on pulmonary hypertension (PH) in rats, and to provide new insights into medication selection for the clinical treatment of PH. Methods Fifty male Sprague-Dawley rats were randomly divided into blank control, PH model, solvent control, RAP 1, and RAP 2 groups. A rat model of PH was induced by left pneumonectomy (PE) and monocrotaline (MCT). At 5 days after PH model establishment, the solvent control group and the RAP 1 group received an intramuscular injection of solvent and RAP, respectively. At 35 days after PH model establishment, the RAP 2 group received an intramuscular injection of RAP. The mean pulmonary artery pressure (mPAP) and the right ventricle/left ventricle plus septum weight ratio (RV/LV+S) were measured in each group. Histopathological changes in the right lung were evaluated by hematoxylin-eosin (HE) staining. The relative expression of alpha-smooth muscle actin (α-SMA) and smooth muscle protein 22-alpha (SM22α) in each group was determined using real-time PCR. Results At 35 days after surgery, the PH model and the solvent control groups had significantly higher mPAP and RV/LV+S than the blank control group, while the RAP 1 and the RAP 2 groups had significantly lower mPAP than the solvent control group (P<0.05). The RV/LV+S in the RAP 1 group was significantly lower than that in the solvent control group (P<0.05); however, there was no significant difference in RV/LV+S between the RAP 2 and the solvent control groups (P>0.05). HE staining in the right lung showed the substantially thickened pulmonary artery wall and narrowed arterial lumen in the PH model and the solvent control groups compared with the blank control group. Different degrees of reversal of the pulmonary artery wall thickening were observed after RAP administration. The results of real-time PCR revealed that the relative expression of α-SMA and SM22α in the PH model and the solvent control groups was significantly lower than in the blank control group, while the relative expression of α-SMA and SM22α in the RAP 1 and the RAP 2 groups was significantly higher than in the solvent control group (P<0.05). Conclusions RAP can reverse the increase in pulmonary artery pressure and the right ventricular hypertrophy probably by regulation of the phenotypic conversion of vascular smooth muscle cells.