多巴胺D5受体突变基因F173L在心脏过表达引起转基因小鼠扩张型心肌病

Over-expression of D5F173L in heart tissue causes dilated cardiomyopathy in the transgenic mice

目的建立心脏特异表达人多巴胺D5受体突变基因F173L(D5F173L)的转基因小鼠,利用该转基因动物模型来研究多巴胺D5受体在心脏肥大发生中的作用机制。方法利用心脏特异启动子α-MHC构建转基因表达载体,显微注射法建立心脏特异表达人多巴胺D5F173L(α-MHC-D5F173L)的转基因小鼠,PCR鉴定转基因小鼠的基因型,Western blot检测多巴胺D5受体在心脏组织中的表达,心脏超声检测转基因小鼠及野生小鼠的心脏结构和功能。光学显微镜检查α-MHC-D5F173L转基因小鼠心脏的病理改变。结果建立了α-MHC-D5F173L转基因小鼠。在3月龄,与野生型小鼠比较,α-MHC-D5F173L转基因小鼠心脏收缩期和舒张期左心室内径均增加[收缩期(3·26±0·42)比(2·58±0·23)mm,舒张期(4·28±0·39)比(3·86±0·25)mm,均P<0·05],收缩期和舒张期左心室容积均增大[收缩期(44·97±14·54)比(24·66±5·34)μL,舒张期(83·99±18·42)比(64·83±9·90)μL,均P<0·05],射血分数及短轴缩短率减少[(48·01±8·73)%比(62·18±4·84)%,(24·23±5·15)%比(33·15±3·52)%,均P<0·05]。病理学观察显示,α-MHC-D5F173L转基因小鼠心腔明显大于野生型,心室壁明显变薄,心肌细胞不均匀肥大,心肌间质纤维增多。结论α-MHC-D5F173L转基因小鼠出6现典型扩张型心肌病的表型。

Objective To establish heart-specific D5F173L transgenic mice and to investigate the mechanism of dopamine D5 receptor in cardiac hypertrophy. Methods The transgenic plasmid was constructed by inserting the human D5F173L gene into the down-stream of α-MHC promoter. The transgenic mice were generated by microinjection. The genotype of transgenic lines was identified by PCR, and the expression levels of the D5 receptor were detected by Western Blotting. The functional and pathologic changes of the heart were analyzed by echocardiography and observed by microscopy. Results The heart-specific D5F173L transgenic mice with high expression levels of D5 receptor were established. Compared with the negative controls, the systolic and diastolic volume and inner diameter of left ventricle of the transgenic mice were greater [volume （44.97±14.54） vs （24.66±5.34）μL, （83.99±18.42） vs （64.83±9.90）μL; inner diameter： （3.26±0.42） vs （2.58±0.23）, （4.28±0.39） vs （3.86±0.25）mm; all P0.05] and the ejection fraction and the fraction shortening decreased [（48.01±8.73）% vs （62.18±4.84）%, （24.23±5.15）% vs （33.15±3.52）%, both P0.05]. Conclusion The heart-specific D5F173L transgenic mice suffer from dilated cardiomyopathy.