OBJECTIVEConotruncal defects (CTD) is a common type of cyanotic congenital heart defects. It was shown that CTD might be produced by ablation of cardiac neural crest during early stage embryos in experimental studies. There were many kinds of genes involved and cardiac alpha-actin (CAA) was one of them. The purpose of this study was to investigate the spatial expression of CAA gene during embryonic heart development, and to explore its role in the pathogenesis of congenital heart defects.

METHODSExperimental chicken embryos were subjected to cardiac neural crest ablation by using electric stimulation at 36-40 hr incubation stage. The embryos and organs of experimental and normal control groups during different developing periods were taken out, RNA was extracted by Trizol, and then reverse transcription was done. The dynamic changes of CAA mRNA expression at different development stages of embryos were assayed by fluorescent real-time PCR. The embryos and tissues at different stages were taken out, and paraffin sections were made. The localizations of CAA antibody expression in the developmental embryos were detected by immunohistochemical analysis (peroxidase-DAB coloration).

RESULTS(1) The expression of CAA gene was detected at early embryo development, and increased subsequently to a stable level. Its expression was mainly limited to heart site, and could be increased along with the maturation of the cardiac muscle. There was no expression or little trace expression in liver, brain, and stomach. (2) There was a significantly low level of CAA gene expression on days 2-7 of chicken embryos whose cardiac neural crest were ablated in comparison with normal controls (P = 0.013). The level of CAA gene expression was also down-regulated on days 7, 9 and 15 of embryonic cardiac tissues (P = 0.029).

CONCLUSIONCAA gene is closely associated with heart development, its expression was adjusted by cardiac neural crest, and its dysfunction may be an important factor leading to congenital heart defects.