Strain Differences in Developmental Vulnerability to Alcohol Exposure via Embryo Culture in Mice

Abstract

Background Prenatal alcohol exposure can result in varying degrees of neurodevelopmental deficits, growth retardation, and facial dysmorphology. Variation in these adverse outcomes not only depends on the dose and pattern of alcohol exposure but also on less well understood interactions among environmental, genetic, and maternal factors. The current study tested the hypothesis that fetal genotype is an important determinant of ethanol teratogenesis by evaluating effects of ethanol exposure via embryo culture in three inbred strains of mice known to differ in the vulnerability of prenatal alcohol exposure in vivo. Methods and results Three strains of mice, C57BL/6N (B6), DBA/2 (D2), and 129S6/SvEvTac (129S6) were assessed in a whole embryo culture beginning on embryonic day 8.25 (E8.25), with or without alcohol administration at 88mM for 6 hours followed by 42 hrs culture in ethanol-free media. Contrasting strain differences in susceptibility were observed for the brain, the face, and other organ systems using the Maele-Fabry and Picard scoring system. The forebrain, midbrain, hindbrain, heart, optic vesicle, caudal neural tube, and hindlimbs of the B6 mice were severely delayed in growth, whereas compared to the respective controls, only the forebrain and optic vesicle were delayed in the D2 mice, and no effects were found in the 129S6 mice. A large number of cleaved(c)-caspase3 positive (+) cells were found in regions of the brain, optic vesicles, cranial nerve nuclei V, VII, VIII, and IX as well as the craniofacial primordial; only a few were found in corresponding regions of the B6 controls. In contrast, only a small number of c-caspase 3-im cells were found in either the alcohol-treated or the controls of the D2 embryos and in 129S6 embryos. The independent apoptotic markers TUNEL and Nile blue staining further confirmed the strain differences in apoptotic responses in both the neural tube and craniofacial primordia. Conclusions Under embryo culture conditions, in which alcohol exposure factors and fetal developmental staging were controlled, and maternal and intrauterine factors were eliminated, the degree of growth retardation and the extent and type of neurodevelopmental teratogenesis varied significantly across strains. Notably, the 129S6 strain was remarkably resistant to alcohol-induced growth deficits, confirming a previous in vivo study, and the D2 strain was also significantly less affected than the B6 strain. These findings demonstrate that fetal genotype is an important factor that can contribute to the variation in fetal alcohol spectrum disorder.

Cellular DNA methylation program during neurulation and its alteration by alcohol exposure

“…Many key genes encoding important morphogen and neurotrophic factors, which are important for differentiation and growth, are located in the floor plate of the neural tube (e.g., the sonic hedgehog and neurotrophic factor fibroblast growth factor; Ye et al, 1998;Dessaud et al, 2008). Temporally, the long alcohol exposure (44 hours) resulted in more severe growth retardation than the shorter (6 hours) alcohol exposure in comparing this and previous studies (Chen et al, 2011). The longer inhibition of DNA methylation also resulted in greater growth delay (Table 2).…”

Neurobehavioral Disorder Associated with Prenatal Alcohol Exposure (ND-PAE): Proposed DSM-5 Diagnosis

“…Research has shown that teratogenic effects of PAE can be influenced by multiple maternal factors, including hormone status (particularly hormones of the HPA axis), nutrition, oxidative stress level, age, parity and years of drinking [117][118][119][120]. Genetic profiles of both mother and fetus may also alter the metabolism of alcohol and risk of physical birth defects, prenatal mortality, learning and other neurobehavioral deficits in the offspring [121][122][123]. Familial patterns of heavy drinking during pregnancy, which may be associated with family and cultural customs, may also result in an increased incidence of ND-PAE.…”

Mitogen-activated protein kinase modulates ethanol inhibition of cell adhesion mediated by the L1 neural cell adhesion molecule

“…P renatal alcohol exposure causes fetal alcohol spectrum disorders (FASD) in up to 2-5% of school-age children and is the leading preventable cause of mental retardation in the Western world (1,2). The prevalence and presentation of FASD are influenced by the quantity, frequency, and timing of drinking and are modified by a variety of environmental, nutritional, epigenetic, and genetic factors (3)(4)(5)(6)(7). The observation that there is greater concordance for fetal alcohol syndrome (FAS) in monozygotic twins than in dizygotic twins suggests that there are susceptibility genes for FASD (8); however, their identification remains elusive.…”