Abstract: Objective To investigate the expression of myocyte-specific enhancer factor 2C (MEF-2C) in the cardiac development of gestational diabetes mellitus (GDM) ’fetal rats, and to explore its mechanism. Methods Adult Sprague-dawley(SD) female rats were randomly divided into control group(n = 24), GDM group(n = 30) were treated by intraperitoneal injection of 2% streptozotocin (STZ) 40 mg/kg body weight after determining the pregnancy, citric acid group(n = 30) were intraperitoneally injected with citric acid-sodium citrate buffer solution after determining the pregnancy, Insulin group (n = 30) were subcutaneously injected with intermediate-acting insulin (NovoMix 30R, 20 U/kg?d) when blood sugar level was 12～15 mmol/L after 72 h of GDM model rats. The changes of blood sugar level and the changes of body weight were observed in pregnant rats of each group. The cardiac tissues of fetal rats in each group were obtained by caesarean section at embryonic day (E) 12、E15 and E19. Then these cardiac tissues of fetal rats were observed and were the histopathological changes of cardiac development under microscope with HE staining; changes in the mRNA expression of MEF-2C by RT-qPCR; changes in the expression of MEF-2C protein by immunohistochemistry and Western blot. Results Dynamic variation of MEF-2C protein level was observed in these group: expression level of MEF-2C protein in the cardiac tissue was observed on E12 and it obviously increased on E15, but it decreasd on E19. Compared with control group, mRNA level and protein content of MEF-2C in GDM group were decreased (P＜0.05). Conclusions The abnormal rate of cardiac development in GDM group is significantly increased. MEF-2C might be associated with cardiac dysplasia in GDM fetal rats.

Key words: myocyte-specific enhancer factor 2C, Gestational diabetes mellitus, embryonic cardiac developement