EFFECT OF ETHANOL ON CARDIAC MYOSIN HEAVY CHAIN GENE EXPRESSION IN CHICK EMBRYOS. † 156

Abstract

Fetal alcohol syndrome (FAS) results from embryo exposure to ethanol. Since gene transcription affects organogenesis, gene expression of one of the major contractile proteins of the heart, myosin heavy chain (MHC), was evaluated following injection of 0.32 ml ethanol into albumin cavity of incubated chick embryos. In 180 embryos treated at 72-80 hours and sacrificed at 14 days, survival was 83%, 53%, 19%, 16% and 0% after use of 10%, 25%, 30%, 35% and 50% ethanol concentrations, respectively. Saline-treated controls had 85% survival. Embryos treated with ≥ 30% of concentrations had body weights 73%(p < 0.001) and heart weights 80% (p < 0.05) of controls, and cardiac defects. MHC gene expression was tested after processing of the heart tissues for RNA isolation and using Northern blot analysis with 32P labeled chicken myosin heavy chain cDNA as a probe. Using 30% ethanol, 2 groups were studied: Early Rx (age 72-80 hrs. and sacrifice 2 and 14 days later) and Late Rx (age 14 days and sacrifice 1, 2 and 3 days later). In both groups, MHC gene expression did not differ from controls. Direct effects of ethanol on primary cultures of 10 day embryonic hearts were also tested. After 48 hours of culture, ethanol treatment using 1:100 and 1:50 dilutions was made in 2 consecutive doses 24 hours apart, and cells harvested 48 hours after the first treatment. No changes in MHC gene expression were seen. Our study suggests that the cardiac teratogenic and developmental effects observed in FAS are not mediated via changes in MHC gene expression.