先天性甲状腺功能减低仔鼠心肌细胞缝隙连接蛋白43和45的表达变化

Expression of connexin 43 and 45 in cardiocytes of mice with congenital hypothyroidism

目的研究甲状腺激素是否通过影响小鼠心室肌细胞连接蛋白43(Cx43)和连接蛋白45(Cx45)的表达,进而影响心脏发育和信号传导。方法清洁级健康成年C57BL/6J小鼠合笼后自行交配产子,分成甲状腺功能减低症组(甲低组)和对照组。甲低组在合笼第10天开始给予母鼠含0.03%甲巯咪唑的饮用水,一直到仔鼠出生7d后。对照组喂养清洁饮用水,其它实验控制因素同甲低组。检测两组仔鼠心室肌细胞Cx43和Cx45的mRNA水平。结果对照组仔鼠心室肌细胞Cx43 mRNA水平在出生时较低,出生7d后开始升高;甲低组出生7d后心室肌细胞Cx43的mRNA水平仍持续减低。与对照组比较,甲低组出生后7d和14d时Cx43的mRNA水平明显减低(均P<0.01)。免疫组化显示与对照组比较,第14天甲低组心室肌细胞Cx43蛋白表达减低(P<0.01)。两组仔鼠出生后心室肌细胞的Cx45 mRNA水平都呈增加趋势,D1、D7和D14比较无统计学差异(均P>0.05)。免疫组化提示两组心室肌闰盘上都存在丰富的Cx45蛋白,无统计学差异(P>0.05)。结论甲低组仔鼠出生后心室肌细胞上Cx43表达持续下降,提示Cx43表达下降可能参与先天性甲状腺功能减低症伴发心脏异常的病理生理过程,但出生14d内未发现Cx45表达与甲状腺素明显相关。

Objective To investigate the expression of Cx43 and Cx45 in cardiocytes of mice with congenital hypothy- roidism （CH）. Methods Healthy female adult C57BL/6J mice were divided into two groups： mice in CH group were fed with 0.03% thiamazole containing water from d10 after mate to d7 after birth; and mice in control group were fed with clean drinking water. The offsprings in both groups were sacrificed on d1,7 and 14, saline perfusion was performed and the ventricle samples were collected for study. Results In control group, the expression level of Cx43 mRNA on cardiocytes decreased after birth and increased from d7; however, that in CH group was not increased after d7. Compared to control group, immunohistochemistry showed that the expression of Cx43 protein in CH group was significantly lower on d14 （P〈0.01）. The expression of Cx45 mRNA increased after birth in both groups; there were not significant differences between two groups at all time points（all P 〉0.05）. Immunohistochemistry showed abundant Cx45 protein on the intercalated disc in both groups without significant difference. Conclusion Results indicate that low thyroid hormone levels may decrease the expression of Cx43 in cardiocytes of mice, which may result in heart disorder. However, the expression of Cx45 is independent to thyroid hormone during gestation period.