Genetic influence on dysmorphogenesis in embryos from different rat strains exposed to ethanol in vivo and in vitro

Background: The aim was to investigate the susceptibility of embryos from 2 rat strains (U and H) to a 48 hours ethanol exposure in early pregnancy, both in vivo and in vitro. Methods: The embryos were studied on gestational days 9 to 11. We used 1 ethanol dose in vivo (6 g/kg × 2), 3 different ethanol concentrations in vitro (88 mM, 132 mM, 176 mM) and also attempted to diminish the teratogenic effect in vitro by supplying the antioxidant N–acetylcysteine (NAC, 0.5 mM) to the culture medium. Results: The U embryos were more damaged by ethanol than the H embryos, both in vivo and in vitro. NAC addition diminished, but failed to completely normalize, the embryonic maldevelopment. Ethanol increased the Bax/Bcl‐2 ratio in the U embryos both in vivo and in vitro, but not in the H embryos. Furthermore, ethanol caused increased Caspase‐3 immunostaining in U embryos, but not in H embryos. Ethanol exposure in vivo did not alter CuZnSOD and MnSOD mRNA levels in U and H embryos. In vitro, however, the ethanol‐exposed U embryos increased their CuZnSOD and MnSOD mRNA levels, whereas the CuZnSOD mRNA was unchanged and MnSOD mRNA decreased in the H embryos, in neither strain did NAC exert any effect. The U embryos increased catalase gene expression in response to ethanol in vivo, but decreased catalase mRNA levels in vitro, changes normalized by NAC. The H embryos did not alter catalase mRNA levels in vivo, but increased gene expression in vitro, with no NAC effect. Ethanol affected the gene expression of the other ROS scavenging enzymes and the developmental genes studied – Bmp‐4, Ret, Shh, Pax‐6 – similarly in the 2 strains. Conclusions: The findings support a role for genetic predisposition, oxidative stress, and apoptosis in ethanol teratogenicity, and suggest that the teratogenic predisposition of the more susceptible U rats may reside, at least in part, in the regulation of the ROS scavenging enzymes in the U embryos.