Prenatal Alcohol Exposure Model Research Articles

Dietary Iron Fortification Normalizes Fetal Hematology, Hepcidin, and Iron Distribution in a Rat Model of Prenatal Alcohol Exposure.

Prenatal alcohol exposure (PAE) causes neurodevelopmental disability. Clinical and animal studies show gestational iron deficiency (ID) exacerbates PAE's behavioral and growth deficits. In rat, PAE manifests an inability to establish iron homeostasis, increasing hepcidin (maternal and fetal), and fetal liver iron while decreasing brain iron and promoting anemia. Here, we hypothesize dietary iron fortification during pregnancy may mitigate alcohol's disruption of fetal iron homeostasis. Pregnant Long-Evans rats, fed iron-sufficient (100ppm iron) or iron-fortified (IF; 500 ppm iron) diets, received either 5g/kg alcohol (PAE) or isocaloric maltodextrin daily on gestational days (GD) 13.5 through 19.5. Maternal and fetal outcomes were evaluated on GD20.5. PAE reduced mean fetal weight (p<0.001) regardless of maternal iron status, suggesting iron fortification did not improve fetal growth. Both PAE (p<0.01) and IF (p=0.035) increased fetal liver iron. In fetal brain, PAE (p=0.015) affected total (p<0.001) and nonheme iron (p<0.001) such that iron fortification normalized (p=0.99) the alcohol-mediated reductions in brain iron and nonheme iron. Iron fortification also improved fetal hematologic indices in PAE including hemoglobin, hematocrit, and mean cell volume (ps<0.001). Iron fortification also normalized hepcidin expression in alcohol-exposed maternal and fetal liver. Neither diet nor PAE affected transferrin (Tf) and ferritin (FTN) content in fetal liver, nor Tf or transferrin receptor in fetal brain. However, IF-PAE fetal brains trended to less FTN content (p=0.074), suggesting greater availability of nonstorage iron. In PAE, hepcidin levels were linearly related to increased liver iron stores and decreased red blood cell count and brain iron. Maternal oral iron fortification mitigated PAE's disruption of fetal iron homeostasis and improved brain iron content, hematologic indices, and hepcidin production in this rat PAE model. Clinical studies show maternal ID substantially enhances fetal vulnerability to PAE, and our work supports increased maternal dietary iron intake may improve fetal iron status in alcohol-exposed pregnancies.

Effects of prenatal alcohol exposure (PAE): insights into FASD using mouse models of PAE.

The potential impact of prenatal alcohol exposure (PAE) varies considerably among exposed individuals, with some displaying serious alcohol-related effects and many others showing few or no overt signs of fetal alcohol spectrum disorder (FASD). In animal models, variables such as nutrition, genetic background, health, other drugs, and stress, as well as dosage, duration, and gestational timing of exposure to alcohol can all be controlled in a way that is not possible in a clinical situation. In this review we examine mouse models of PAE and focus on those with demonstrated craniofacial malformations, abnormal brain development, or behavioral phenotypes that may be considered FASD-like outcomes. Analysis of these data should provide a valuable tool for researchers wishing to choose the PAE model best suited to their research questions or to investigate established PAE models for FASD comorbidities. It should also allow recognition of patterns linking gestational timing, dosage, and duration of PAE, such as recognizing that binge alcohol exposure(s) during early gestation can lead to severe FASD outcomes. Identified patterns could be particularly insightful and lead to a better understanding of the molecular mechanisms underlying FASD.

Hippocampal hyperexcitability in fetal alcohol spectrum disorder: Pathological sharp waves and excitatory/inhibitory synaptic imbalance

Prenatal alcohol exposure (PAE) can lead to long-lasting neurological alterations that may predispose individuals to seizures and neurobehavioral dysfunction. To date, there exists limited information regarding the underlying pathophysiological mechanisms. The hippocampal CA3 region generates excitatory population activity, called sharp waves (SPWs), that provide an ideal model to study perturbations in neuronal excitability at the network and cellular levels. In the present study, we utilized a mouse model of PAE and used dual extracellular and whole-cell patch-clamp recordings from CA3 hippocampal pyramidal cells to evaluate the effect of 1st trimester-equivalent ethanol exposure (10% v/v) on SPW activity and excitatory/inhibitory balance. We observed that PAE significantly altered in vitro SPW waveforms, with an increased duration and amplitude, when compared to controls. In addition, PAE slices exhibited reduced pharmacological inhibition by the GABA-A receptor antagonist bicuculline (BMI) on SPW activity, and increased population spike paired-pulse ratios, all indicative of network disinhibition within the PAE hippocampus. Evaluation of PAE CA3 pyramidal cell activity associated with SPWs, revealed increased action potential cell firing, which was accompanied by an imbalance of excitatory/inhibitory synaptic drive, shifted in favor of excitation. Moreover, we observed intrinsic changes in CA3 pyramidal activity in PAE animals, including increased burst firing and instantaneous firing rate. This is the first study to provide evidence for hippocampal dysfunction in the ability to maintain network homeostasis and underlying cellular hyperexcitability in a model of PAE. These circuit and cellular level alterations may contribute to the increased propensity for seizures and neurobehavioral dysfunction observed in patients with a history of PAE.

Differential expression of astrocytic connexins in a mouse model of prenatal alcohol exposure

Maternal alcohol consumption during gestation can cause serious injury to the fetus, and may result in a range of physiological and behavioral impairments, including increased seizure susceptibility, that are collectively termed fetal alcohol spectrum disorder (FASD). The cellular mechanisms underlying increased seizure susceptibility in FASD are not well understood, but could involve altered excitatory coupling of neuronal populations mediated by gap junction proteins. We utilized a mouse model of the prenatal alcohol exposure (PAE) to study the expression pattern of connexin (Cx) major components of gap junctions, and pannexin proteins, which form membrane channels, in the brain of 2–3weeks old PAE and control postnatal offspring. PAE during the first trimester-equivalent period of pregnancy in mice resulted in significant up-regulation of Cx30 mRNA and Cx30 total protein in the hippocampus of PAE animals compared to age-matched controls. Surface level expression of both dimeric and monomeric Cx30 were also found to be significantly up-regulated in both hippocampus and cerebral cortex of PAE animals compared to age-matched controls. On the membrane surface, the fast migrating form of Cx43 was found to be up-regulated in the hippocampus of PAE mice. However, we did not see any up-regulation of the phosphorylated forms of Cx43 on the membrane surface. These results indicate that the expression and processing of astrocytic connexins (Cx30, Cx43) are up-regulated in the brain of PAE offspring, and these changes could play a role in the cerebral hyperexcitability observed in these animals.

Commentary: Linking Cortical and Subcortical Developmental Trajectories to Behavioral Deficits in a Mouse Model of Prenatal Alcohol Exposure.

Commentary: Linking Cortical and Subcortical Developmental Trajectories to Behavioral Deficits in a Mouse Model of Prenatal Alcohol Exposure.

GESTATIONAL ALCOHOL EXPOSURE IMPAIRS MATERNAL‐FETAL IRON HOMEOSTASIS THROUGH HEPCIDIN DYSREGULATION

Prenatal alcohol exposure (PAE) causes lifelong neurodevelopmental deficits. Gestational iron deficiency (ID) mimics these disabilities. We reported previously that gestational ID synergizes with alcohol to substantially worsens PAE's growth and learning deficits. The effects of PAE upon fetal-maternal iron homeostasis is unknown. Using a 2nd trimester rat PAE model (5 g/kg ethanol, GD 13.5-19.5), we measured iron content and iron homeostatic biomarkers in fetal brain and liver under maternal iron sufficiency (IS) and ID. We report here that PAE impairs fetal adaptation to maternal IS and ID. Whereas PAE increased fetal liver iron content (IS: 155 vs 182 ppm; ID: 104 vs 166 ppm), it significantly decreased fetal brain iron (IS: 20.6 vs 16.2 ppm) to levels indistinguishable from ID (14.3 vs 14.9 ppm). Fetal liver ferritin expression parallels iron content. PAE also impaired fetal brain adaptation to ID, evidenced by a 50% decrease in brain transferrin (TF) and transferrin receptor (TFRc) expression. PAE did not affect TFRc expression in IS fetal brain, nor TF and TFRc in fetal liver regardless of iron status. Finally, PAE caused a 蠅3-fold induction of hepcidin expression in both fetal and maternal liver, regardless of iron status. We propose that the elevated hepcidin under PAE may drive iron into liver stores at the expense of developing brain. Our results partly explain why maternal ID substantially exacerbates alcohol's neurodevelopmental damage. In summary, alcohol disrupts fetal iron homeostasis and prevents fetal adaptation to maternal ID. ID is common in alcohol-abusing women. Correcting this dysregulation is central for the successful normalization of iron status in women at risk for PAE. Supp: AA21311

Prenatal alcohol exposure modifies glucocorticoid receptor subcellular distribution in the medial prefrontal cortex and impairs frontal cortex-dependent learning.

Prenatal alcohol exposure (PAE) has been shown to impair learning, memory and executive functioning in children. Perseveration, or the failure to respond adaptively to changing contingencies, is a hallmark on neurobehavioral assessment tasks for human fetal alcohol spectrum disorder (FASD). Adaptive responding is predominantly a product of the medial prefrontal cortex (mPFC) and is regulated by corticosteroids. In our mouse model of PAE we recently reported deficits in hippocampal formation-dependent learning and memory and a dysregulation of hippocampal formation glucocorticoid receptor (GR) subcellular distribution. Here, we examined the effect of PAE on frontal cortical-dependent behavior, as well as mPFC GR subcellular distribution and the levels of regulators of intracellular GR transport. PAE mice displayed significantly reduced response flexibility in a Y-maze reversal learning task. While the levels of total nuclear GR were reduced in PAE mPFC, levels of GR phosphorylated at serines 203, 211 and 226 were not significantly changed. Cytosolic, but not nuclear, MR levels were elevated in the PAE mPFC. The levels of critical GR trafficking proteins, FKBP51, Hsp90, cyclophilin 40, dynamitin and dynein intermediate chain, were altered in PAE mice, in favor of the exclusion of GR from the nucleus, indicating dysregulation of GR trafficking. Our findings suggest that there may be a link between a deficit in GR nuclear localization and frontal cortical learning deficits in prenatal alcohol-exposed mice.

Dissecting Role of Sleep in Abnormal Neurocognitive Development in an Animal Model of Prenatal Alcohol Exposure

Dissecting Role of Sleep in Abnormal Neurocognitive Development in an Animal Model of Prenatal Alcohol Exposure It has been well established that human conditions with insufficient or restricted sleep have detrimental consequences, including cognitive, affective, cardiovascular and endocrine, and contribute to poor quality of life. Development of insomnia depends on genetic, epigenetic and environmental factors, and may have origins in early ontogenesis. Existing data suggest that poor sleep and increased behavioral arousal can result from prenatal adversities such as exposure to psychoactive substances or malnutrition. One of the major risk factors during the prenatal period is maternal alcohol consumption. It occurs in over 10% of pregnancies, leading to adverse consequences such as the Fetal Alcohol Spectrum Disorders (FASD) affecting 2-5% of births in the United States and Western European countries.

A Limited Access Mouse Model of Prenatal Alcohol Exposure that Produces Long‐Lasting Deficits in Hippocampal‐Dependent Learning and Memory

It has been estimated that approximately 12% of women consume alcohol at some time during their pregnancy, and as many as 5% of children born in the United States are impacted by prenatal alcohol exposure (PAE). The range of physical, behavioral, emotional, and social dysfunctions that are associated with PAE are collectively termed fetal alcohol spectrum disorder (FASD). Using a saccharin-sweetened ethanol solution, we developed a limited access model of PAE. C57BL/6J mice were provided access to a solution of either 10% (w/v) ethanol and 0.066% (w/v) saccharin or 0.066% (w/v) saccharin (control) for 4 h/d. After establishing consistent drinking, mice were mated and continued drinking during gestation. Following parturition, solutions were decreased to 0% in a stepwise fashion over a period of 6 days. Characterization of the model included measurements of maternal consumption patterns, blood ethanol levels, litter size, pup weight, maternal care, and the effects of PAE on fear-conditioned and spatial learning, and locomotor activity. Mothers had mean daily ethanol intake of 7.17 ± 0.17 g ethanol/kg body weight per day, with average blood ethanol concentrations of 68.5 ± 9.2 mg/dl after 2 hours of drinking and 88.3 ± 11.5 mg/dl after 4 hours of drinking. Food and water consumption, maternal weight gain, litter size, pup weight, pup retrieval times, and time on nest did not differ between the alcohol-exposed and control animals. Compared with control offspring, mice that were exposed to ethanol prenatally displayed no difference in spontaneous locomotor activity but demonstrated learning deficits in 3 hippocampal-dependent tasks: delay fear conditioning, trace fear conditioning, and the delay nonmatch to place radial-arm maze task. These results indicate that this model appropriately mimics the human condition of PAE and will be a useful tool in studying the learning deficits seen in FASD.

134: Normative data for sonographically determined amniotic fluid volume at the time of nuchal translucency screening: Using the largest vertical pocket technique

MODEL JUDETTE LOUIS, JOHN HOTRA, JAMES JANISSE, ROBERT SOKOL, CaseMetrohealth Medical Center, Cleveland, Ohio, Wayne State University, Detroit, Michigan OBJECTIVE: We recently reported a strong association between alcohol exposure during human pregnancy and extreme preterm delivery; here, we sought to validate a previously reported murine model to facilitate mechanistic studies. STUDY DESIGN: Nulliparous 10-12 week old female C57BL/6J mice were randomized to one of 20 treatment groups and bred using a timed breeding method. Each mouse received one of four doses of alcohol (0, 4, 5 or 6 grams of alcohol/kg body weight) on one of five gestational days (GD) (GD 10, 15, 16, 17, 18). Cages were monitored every 6h for deliveries. Data were analyzed utilizing a 4x5 ANOVA. RESULTS: The alcohol dose by day of exposure interaction was significant (p 0.015), while the main effects for alcohol dose (p 0.942), and day of exposure (p 0.157) on gestational length were not. Examination of the interaction revealed a differential effect of day of exposure on the control group, compared to the alcohol exposed groups. Among the control group mice receiving no alcohol, the GD 10 group had a significantly longer gestation (mean 20.5) than the GD15 (mean 19.2), 17 (mean 19.4) and 18 (mean 19.3) groups. However, the day of exposure was not related to length of gestation in the alcohol groups (p 0.157). Average length of gestation for the alcohol groups was 19.3 days. CONCLUSION: Failing to confirm a previous study in this murine prenatal alcohol exposure model, no relation to gestational duration was detected. An effect may have been cloaked by an apparent major effect of intubation. Again attempting to confirm this model with additional controls or another dosing method or finding other animal models would facilitate further study of prenatal alcohol exposure and preterm delivery risk.

Genetic Influences on Craniofacial Outcome in an Avian Model of Prenatal Alcohol Exposure

Background: Understanding the basis for ethanol's teratogenic effects may inform the etiology of fetal alcohol syndrome. Here we investigate how genetic background and susceptibility to ethanol-induced neural crest apoptosis contribute to the distinctive craniofacial phenotype observed after prenatal alcohol exposure. Methods: Nine different chick strains were exposed to ethanol at gastrulation. The sensitivity of these embryos to ethanol-induced neural crest apoptosis was reported elsewhere (Debelak and Smith, 2000). Here, these embryos were permitted to develop until embryonic day 10, when facial morphogenesis was largely complete, and cephalometric measurements were made on cleared skulls. Shifts in facial growth were correlated against the severity of ethanol-induced apoptosis in facial precursors. Results: The facial shape produced by ethanol exposure was a function of the embryos’ genetic strain. Three general responses were observed: apparent midfacial flattening (Babcock B300 x Hampshire Red, ISA-Babcock, HyLine W98, and HyLine W36 strains), overall facial expansion (Spafas and Babcock B300 strains), or overall facial hypoplasia (DeKalb strains). When dose and timing of exposure were held constant, the embryo's genetic background predicted the facial outcome. For ethanol-sensitive strains, apoptosis of facial precursor populations was required to produce the facial defects. That some strains had essentially normal faces despite extensive cell death indicated a capacity to recover from the earlier neural crest losses. Conclusions: We propose that ethanol's effects on craniofacial development are multifactoral, and these influences may include susceptibility to apoptosis, regenerative capacity, and compensatory outgrowth of the facial primordia. The embryo's genetic background may modulate these events. The high and low responder chick strains are useful tools to dissect these contributions.

Genetic Influences on Craniofacial Outcome in an Avian Model of Prenatal Alcohol Exposure

Understanding the basis for ethanol's teratogenic effects may inform the etiology of fetal alcohol syndrome. Here we investigate how genetic background and susceptibility to ethanol-induced neural crest apoptosis contribute to the distinctive craniofacial phenotype observed after prenatal alcohol exposure. Nine different chick strains were exposed to ethanol at gastrulation. The sensitivity of these embryos to ethanol-induced neural crest apoptosis was reported elsewhere (Debelak and Smith, 2000). Here, these embryos were permitted to develop until embryonic day 10, when facial morphogenesis was largely complete, and cephalometric measurements were made on cleared skulls. Shifts in facial growth were correlated against the severity of ethanol-induced apoptosis in facial precursors. The facial shape produced by ethanol exposure was a function of the embryos' genetic strain. Three general responses were observed: apparent midfacial flattening (Babcock B300 x Hampshire Red, ISA-Babcock, HyLine W98, and HyLine W36 strains), overall facial expansion (Spafas and Babcock B300 strains), or overall facial hypoplasia (DeKalb strains). When dose and timing of exposure were held constant, the embryo's genetic background predicted the facial outcome. For ethanol-sensitive strains, apoptosis of facial precursor populations was required to produce the facial defects. That some strains had essentially normal faces despite extensive cell death indicated a capacity to recover from the earlier neural crest losses. We propose that ethanol's effects on craniofacial development are multifactoral, and these influences may include susceptibility to apoptosis, regenerative capacity, and compensatory outgrowth of the facial primordia. The embryo's genetic background may modulate these events. The high and low responder chick strains are useful tools to dissect these contributions.