脂肪因子CTRP9对异丙肾上腺素诱导小鼠心肌重构的影响

Effect of lipid factor CTRP9 on myocardial remodeling induced by isoproterenol in mice

目的本试验旨在探讨CTRP9对ISO诱导的心肌重构的影响。方法雄性C57BL/6J小鼠分为4组（n=10），5mg／kg每12小时1次的方式和剂量皮下注射ISO12d，同时以200μg·kg^-1·d^-1皮下注射的方式给予人重组CTRP912d。免疫组化染色CTRP9的表达和细胞定位；超声心动图比较各组小鼠心室壁厚度以及心功能，评价模型组小鼠心脏结构和心功能；取心脏后比较各组小鼠心脏质量／体质量、肺脏质量／体质量、心脏质量／胫骨长；HE染色比较心肌细胞横截面积；RT-PCR检测比较各组小鼠心肌肥厚标志物和纤维化标志物的转录水平；免疫印迹评价分子蛋白的改变。结果免疫组化结果显示：模型组小鼠CTRP9的表达明显下调（P〈0．05）；超声结果显示：模型组小鼠左室舒张期内径（LVDd，4．00mm比4．67mm）、左室收缩期内径（LVDs，2．60mm比3．12mm）均大于对照组（P〈0．05），而左室射血分数（LVEF，73％比55％）以及短轴缩短率（FS，39％比21％）均小于对照组（P〈0．05）；模型组小鼠心脏质量／体质量、肺脏质量／体质量、心脏质量／胫骨长以及心肌细胞横截面积明显高于对照组（P〈0．05）；RT-PCR结果显示模型组小鼠心肌肥厚标志物（ANP、BNP以及β-MHC）明显增高（P〈0．05）；PSR染色结果显示模型组小鼠心脏纤维化程度加重，且纤维化标志物（Ⅰ型胶原，Ⅲ型胶原和α平滑肌动蛋白）的转录水平均高于对照组（P〈0．05）；而CTRP9处理后心肌肥厚程度明显降低，心脏纤维化程度减轻，心功能明显改善（P〈0．05）。免疫印迹结果显示：模型组小鼠心脏iNOS的表达未见改变，而nNOS和eNOS的表达有所增加，但是CTRP9进一步增加eNOS和nNOS的表达，从而增加一氧化氮的合成。结论CTRP9通过增加eNOS和nNOS来源的一氧化氮保护ISO诱导的心肌重构。

Objective To investigate the effect of lipid factor CTRP9 on myocardial remodeling induced by isoproterenol in mice. Methods Male C57BL/6J mice were randomly assigned to four groups （n = 10 per group）, then mice were administered 5 mg/kg ISO q12h for 12 days by daily subcutaneous injection to induce myocardial remodeling model. Mice also received subcutaneous injection of CTRP9 （200 μg · kg^-1 · d^-1 ） for 12days. Eehoeardiography was performed to compare the ventrieular wall thickness and cardiac function. Heart weight/body weight （HW/BW）, lung weight/body weight （LW/BW）, heart weight/tibia length （HW/TL） and cross-sectional area of cardiomyoeytes were compared between groups. The cardiac hypertrophic markers and fibrotic markers were also compared by RT-PCR between the two groups. Molecular protein changes were evaluated by Western blot. Results CTRP9 was down-regulated in model group. The LVEDd （4. 00 mm vs 4. 67mm）, LVEDs （2. 60 mm vs 3.12 mm） in mode group were both higher than control group while the LVEF （73% vs 55% ） and FS （39% vs 21% ） were reduced in mode group. Compared with the control group, the HW/BW, LW/BW, HW/TL and cross-sectional area of eardiomyoeytes were much higher in mode group （P 〈 0. 05 ）. The transcription level of hypertrophic markers （ANP, BNP, β-MHC ） were elevated. Left ventrieular collagen volume was increased as well as the transcription level of fibrosis markers collagen Ⅰ , collagen Ⅲ and α-SMA. Western blot results indicated that CTRP9 increased nNOS and eNOS derived NO production but not iNOS expression. Conclusion CTRP9 could protect against ISO induced myocardial remodeling by increasing nNOS and eNOS derived NO production.