Ethanol embryotoxicity: direct effects on mammalian embryos in vitro

Oxidative stress and DNA damage in the mechanism of fetal alcohol spectrum disorders

This review covers molecular mechanisms involving oxidative stress and DNA damage that may contribute to morphological and functional developmental disorders in animal models resulting from exposure to alcohol (ethanol, EtOH) in utero or in embryo culture. Components covered include: (a) a brief overview of EtOH metabolism and embryopathic mechanisms other than oxidative stress; (b) mechanisms within the embryo and fetal brain by which EtOH increases the formation of reactive oxygen species (ROS); (c) critical embryonic/fetal antioxidative enzymes and substrates that detoxify ROS; (d) mechanisms by which ROS can alter development, including ROS-mediated signal transduction and oxidative DNA damage, the latter of which leads to pathogenic genetic (mutations) and epigenetic changes; (e) pathways of DNA repair that mitigate the pathogenic effects of DNA damage; (f) related indirect mechanisms by which EtOH enhances risk, for example by enhancing the degradation of some DNA repair proteins; and, (g) embryonic/fetal pathways like NRF2 that regulate the levels of many of the above components. Particular attention is paid to studies in which chemical and/or genetic manipulation of the above mechanisms has been shown to alter the ability of EtOH to adversely affect development. Alterations in the above components are also discussed in terms of: (a) individual embryonic and fetal determinants of risk and (b) potential risk biomarkers and mitigating strategies. FASD risk is likely increased in progeny which/who are biochemically predisposed via genetic and/or environmental mechanisms, including enhanced pathways for ROS formation and/or deficient pathways for ROS detoxification or DNA repair.

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.

The Ascidian Embryo Teratogenicity assay in Ciona intestinalis as a new teratological screening to test the mixture effect of the co-exposure to ethanol and fluconazole

The aim of this work was to evaluate the Ascidian Embryo Teratogenicity assay (AET) as new alternative invertebrate model to test the developmental effects of the co-exposure to ethanol and fluconazole. Ciona intestinalis embryos were exposed to the azolic fungicide fluconazole, (FLUCO, 7.8-250μM), to ethanol (Eth, 0.01-0.5%) and to their mixture (0.01% Eth+FLUCO 7.8-250μM) from neurula to larval stage. At the end of the exposure period, larvae were morphologically evaluated and benchmark analysis performed by using the PROAST modelling software. Both compounds were teratogenic in a concentration-related manner, particularly affecting the pigmented organs. The co-exposure to Eth enhanced the effects of FLUCO, the additive hypothesis was not rejected by the modelling. The results demonstrated that AET could be considered a good vertebrate-free alternative model for toxicological investigation in embryos.

Species extrapolation of life-stage physiologically-based pharmacokinetic (PBPK) models to investigate the developmental toxicology of ethanol using in vitro to in vivo (IVIVE) methods

To provide useful alternatives to in vivo animal studies, in vitro assays for dose-response assessments of xenobiotic chemicals must use concentrations in media and target tissues that are within biologically-plausible limits. Determining these concentrations is a complex matter, which can be facilitated by applying physiologically-based pharmacokinetic (PBPK) models in an in vitro to in vivo extrapolation (IVIVE) paradigm. We used ethanol (EtOH), a ubiquitous chemical with defined metrics for in vivo and in vitro embryotoxicity, as a model chemical to evaluate this paradigm. A published series of life-stage PBPK models for rats was extended to mice, yielding simulations that adequately predicted in vivo blood EtOH concentrations (BECs) from oral, intraperitoneal, and intravenous routes in nonpregnant and pregnant adult mice. The models were then extrapolated to nonpregnant and pregnant humans, replicating BEC data within a factor of two. The rodent models were then used to conduct IVIVEs for rodent and whole-embryo culture embryotoxicity data (neural tube closure defects, morphological changes). A second IVIVE was conducted for exposure scenarios in pregnant women during critical windows of susceptibility for developmental toxicity, such as the first 6-to-8 weeks (prerecognition period) or mid-to-late pregnancy period, when EtOH consumption is associated with fetal alcohol spectrum disorders. Incorporation of data from human embryonic stem cell studies led to a model-supported linkage of in vitro concentrations with plausible exposure ranges for pregnant women. This effort demonstrates benefits and challenges associated with use of multispecies PBPK models to estimate in vivo tissue concentrations associated with in vitro embryotoxicity studies.

Organic solvents impair life-traits and biomarkers in the New Zealand mudsnail Potamopyrgus antipodarum (Gray) at concentrations below OECD recommendations

Potamopyrgus antipodarum is a gastropod mollusk proposed for use in the development of reproduction tests within the Organization for Economic Cooperation and Development (OECD). Numerous chemicals, including endocrine disrupters, are relatively water-insoluble, and water-miscible solvents are currently used for testing them. OECD recommends a maximum concentration of 100 μll(-1). As several studies highlighted effects of lower concentrations of solvents, this study assessed the effects of 20 μll(-1) acetone, ethanol, methanol and dimethylsulfoxide (DMSO) on juvenile and adult snails during 42 days. Ethanol decreased juvenile growth, while acetone increased the rate of embryonic development. All solvents increased estradiol-like levels in adult snails. DMSO only increased mRNA expression of vitellogenin-like gene, while acetone, ethanol and methanol decreased mRNA expression of three nuclear receptor (estrogen receptor-like, ecdysone-induced protein and chicken ovalbumin upstream promoter transcription factor) genes as well as of genes encoding proteins involved in genomic (prohibitin-2) and non-genomic (striatin) pathways of estrogens activity in vertebrates. This study highlights the confounding effects of low concentrations of solvents and recommends avoiding their use. Where solvent use is inevitable, their concentrations and type should be investigated for suitability for the measured endpoints prior to use in chemical testing strategies.

Critical periods for alcohol teratogenesis in mice, with special reference to the gastrulation stage of embryogenesis

Studies directed towards determining a 'critical' developmental period for the induction of neural, ocular and craniofacial malformations typical of those in severe forms of the fetal alcohol syndrome (FAS) are described here. Sequential developmental analyses of C57Bl/6J mice whose mothers had been given alcohol either intraperitoneally or by gastric intubation on the seventh day of pregnancy (a time corresponding to three weeks after fertilization in humans) illustrate that early deficiencies in the anterior aspect of the embryonic disc of embryos at the gastrulation stage lead to defects characteristic of FAS. These include microcephaly, small nose, long upper lip with deficient philtral component, short palpebral fissures, microphthalmia and tortuous retinal vessels, as well as other eye defects involving primarily the anterior segment. Brain malformations are most marked in the derivatives of the ventromedial forebrain. Gastrulation is a period of intense mitotic activity (particularly in the developing mesoderm) in mammalian embryos. This, together with other studies showing that alcohol suppresses rates of cell division, suggests that alcohol-induced deficiencies in gastrulating mesodermal cells (cells responsible for inducing and maintaining neuroepithelial differentiation), as well as cellular deficiencies in the other germ layers in the anteromedial aspect of the embryonic disc, may play a significant role in the subsequent developmental abnormalities observed.

Growth of rat embryos in the serum of alcohol drinkers

Seven healthy male volunteers who had fasted overnight consumed Scotch whisky (70-85 g absolute alcohol) in a period of 15 minutes after venesection at 9.30 a.m. An hour later a further quantity of blood was collected. Rat embryos (9.5 days of gestation) grown for four hours in 'post-drink' serum (115 mg alcohol/100 ml serum) followed by 44 hours in 'pre-drink' serum were compared to controls cultured in normal human serum for 48 hours. All cultures contained 90% human serum and 10% rat serum. The embryos were examined morphologically and their protein content was measured to assess in vitro growth and differentiation. The results demonstrated the teratogenic and growth-retarding effects of alcohol ingestion. Addition of ethanol (120 mg/100 ml) to the culture medium produced similar results. Culture of 9.5-day rat embryos for 24 hours in 'post-drink' serum (115 mg/100 ml alcohol) containing 10 or 20 micrograms acetaldehyde/ml or in pre-drink serum containing similar amounts of acetaldehyde showed a toxic effect of acetaldehyde only at concentrations of 20 micrograms/ml, in the absence of alcohol.

Teratogenic Effects of the Interaction Acetylsalicylic Acid (ASA) and Ethanol: Morphologic and Morphometric Evaluation of the Lingual Epithelium in Rat Fetuses

The objective of the present work was to evaluate the teratogenic effects of the interaction between acetylsalicylic acid (ASA) and ethanol on the epithelium of the lingual mucosa in rat fetuses. On the 10th pregnancy day, a single intraperitoneal ethanol dose (2.96 g/kg body weight) (Group I), ASA (200 mg/kg body weight) (Group II) and ASA plus ethanol, in the same doses (Group III), or saline (Group IV - control), were administrated. The epithelial alterations were assessed by means of histological and morphometric methods, on posterior dorsal, anterior dorsal and ventral regions of the tongue. ASA reduced, in rat fetuses, the ethanol deleterious effects on nuclear size in the epithelial prickle cell of the lingual mucosa. On the other hand, ASA did not influence the effects of ethanol in both epithelial layers of the lingual mucosa, when the nuclear shape, cell volume or epithelial layers thickness were evaluated.

Caffeine induces in vivo premature appearance of telencephalic vesicles

Caffeine administered to pregnant mice during germinative neuroepithelium preparation (embryonic days 8-10) dramatically accelerated primitive neuroepithelium evagination into telencephalic vesicles, versus age-matched controls. This histologically-documented, dose-dependent effect seemed reversible during subsequent neuronal migration if caffeine exposure was discontinued. Our in vivo model provides a new tool for studying telencephalic symmetry acquisition and for identifying genes potentially involved in holoprosencephaly, a developmental disorder characterized by defective telencephalic vesicle formation.

Maternal protein restriction early in rat pregnancy alters brain development in the progeny

We assessed the effects of a dietary protein restriction (5% vs. 20% casein in diet) initiated at conception and imposed during the first 2 weeks of rat gestation on postnatal brain development. At the end of the malnutrition period, protein-restricted animals exhibited significantly smaller fetal body weight and brain cortical thickness than controls. At birth and thereafter, body weight was normalized in the progeny. Similarly, brain weight and cytoarchitecture were normal in postnatal animals. In contrast, we observed, during the first 2 postnatal weeks, several abnormalities of brain development which affected all the studied areas for most of the studied parameters: (i) delayed astrocytogenesis as shown by a reduced GFAP staining; (ii) delayed production of hyaluronan in the extracellular matrix studied with binding of biotinylated hyaluronectin; (iii) abnormal neuronal differentiation as shown by reduced expression of MAP-5 and increased expression of MAP-1; (iv) abnormal synaptogenesis as shown by the increased expression of synaptophysin in the basal ganglia; (v) decreased programmed cell death. In adult prenatally protein-restricted animals, all the above parameters were normalized excepted MAP-1 labeling which remained high. In addition, we observed slight alterations of the ventilatory response to hypoxia in adult animals. The present study demonstrates that early protein malnutrition during embryonic development induces multiple, transient alterations of brain development. However, the almost complete normalization in adults of brain architecture and differentiation as well as our physiological data strongly suggest a remarkable plasticity of the developing brain following an early aggression.

Changes in brain glucose levels and glucose transporter protein isoforms in alcohol- or nicotine-treated chick embryos

Suppression of fetal brain growth during pregnancy as the result of maternal smoking or alcohol consumption leads to significant problems for the offspring as well as for the society who must care for these individuals. Chronic maternal intake of cigarette smoke is frequently observed in humans and studies using animal models suggest that in utero nicotine exposure is an important component of the growth suppression that results. Similarly, maternal consumption of alcohol (ethanol) has a profound, negative effect on fetal growth. The developing fetal central nervous system (CNS) is sensitive to the growth inhibitory effect of nicotine or alcohol and morphological as well as functional CNS deficits may result from fetal exposure. Using an embryonic chick model which minimizes drug-induced changes in maternal nutrition and behavior, the studies presented here indicate that nicotine or alcohol exposure during early embryonic development inhibits brain growth to a degree comparable to that seen in the rest of the organism, i.e., there was no 'brain sparing' in this model. Glucose content per milligram tissue was markedly decreased in brains of the nicotine-treated embryos but was not significantly different in the alcohol-exposed embryos. Western blots of fetal brain glucose transporter protein isoforms showed no change in the Glut 3 transporter content in the growth suppressed brains compared to vehicle-treated brains. The Glut 1 55 kilodalton (kd) isoform protein content was significantly decreased in the nicotine-treated brains but unchanged in the ethanol-treated brains, while the reverse was true for the Glut 1 45 kd isoform. Thus, the changes in the 55 kd isoform protein content were correlated with tissue glucose levels in the ethanol- and nicotine-treated embryos.

Ethanol effects on postimplantation rat embryos: influence of zinc and methionine

Organic zinc salts and thiols, administered simultaneously, protect mice synergistically against ethanol toxicity. Moreover, chronic ethanol consumption could affect the bioavailability of zinc and amino acids such as methionine. This could result in impaired embryonic growth and development. The influence of zinc and methionine on ethanol-induced embryopathy was investigated by simultaneous administration of ethanol, zinc and methionine to pregnant rats from gestational day 6 through 12. Ethanol was given in the form of a liquid diet; zinc administered i.p., and methionine was given by gavage. The ethanol group received the liquid ethanol diet; the ethanol + zinc and methionine group received the ethanol diet, zinc and methionine; and the pair-fed control group was given an isocaloric control diet. On day 12 of gestation, embryos of ethanol alone treated rats revealed a significantly reduced embryonic protein content, number of somites, crown-rump length, and lower morphological score (embryological differentiation) compared to the pair-fed control embryos. However, embryonic growth and developmental parameters in the ethanol, zinc and methionine treated group were not significantly different from those exposed to ethanol alone.

Morphologic changes in offspring of female mice exposed to ethanol before conception

OBJECTIVE

Our purpose was to evaluate the mutagenic effects of preconceptional ethanol exposure by use of the mouse model.

STUDY DESIGN

Fifty-three adult female CF-1 mice were divided into one of five groups with or without an ethanol diet for 28 days. Mice were then superovulated and mated. On day 14 of gestation all mice were killed and fetuses removed and examined for abnormalities.

RESULTS

The mutation index for the study and mutagen groups was similar (48% vs 41%). The percentage of any anatomic abnormality in any treatment group were between 50% and 100%. Anomalies of the abdominal wall were most commonly seen in the mutagenic groups.

CONCLUSIONS

Chronic ethanol exposure in the female mouse before conception yields anatomic abnormalities in the offspring. These mutagenic effects may be variable in that they may result in a dominant lethal mutation or a delayed interference with organogenesis. Ethanol consumption, whether before or after conception, poses an unfavorable outcome in the offspring produced.

Ethanol in utero induces epithelial cell damage and altered kinetics in the developing rat intestine

The effect of prenatal ethanol exposure on the intestinal maturation of rat fetuses was investigated to understand the nutritional alterations found in the offspring of alcoholic mothers. Female Wistar rats were maintained on solid diet and 25% ethanol solution as drinking fluid during pregnancy, and non-alcoholic isocaloric pregnant mothers were used as controls. At birth, intestines from unsuckled pups were removed for study. The weight and length of the intestine decreased significantly when ethanol was present in utero. Ultrastructural evaluation of the epithelium revealed loss of contact between neighboring enterocytes and abnormal dilation of the cisternae of the Golgi apparatus in ethanol-exposed pups. Further, increased lysosome-like vesiculation and enhanced lysosomal beta-galactosidase activity was observed in these neonates. The total number of absorptive enterocytes in the epithelium was reduced by 30% in ethanol-exposed neonates as compared to controls, due to altered cell growth and death during fetal life. Ethanol in utero stimulated epithelial cell migration which compensated cell loss, as demonstrated by 5'-Bromodeoxyuridine labeling. These findings could have important implications for the assimilation of nutrients and failure to thrive in infants with fetal alcohol syndrome.

Effects of alcohols on murine preimplantation development: relationship to relative membrane disordering potency

During in vitro culture of murine preimplantation embryos, we have observed that exposure to 0.1% ethanol induces an immediate increase in intracellular calcium levels and subsequently accelerates embryogenesis. If the observed effects of ethanol on developing embryos is mediated by its membrane disordering potency, we hypothesized that the relative membrane disordering potencies of related alcohols would correspondingly effect embryonic intracellular calcium levels and developmental rates. Two-cell embryos were exposed to 0.1% ethanol or 0.05 to 1.0% (w/v) n-butanol, n-propanol, isopropanol, 1,2-propanediol, glycerol, or methanol for 24 hr at 37 degrees C, and development to the blastocyst stage was monitored after 5 days. n-Butanol, n-propanol, isopropanol, and methanol treatment caused a dose-dependent inhibition (p < 0.01) of development to the blastocyst stage, whereas 1,2-propanediol or glycerol neither accelerated nor inhibited development. In a second experiment, 8-cell morulae were treated with 1,2-propanediol or glycerol, and cavitation rates were examined. There was no significant difference from control embryos in the onset of cavitation or the blastocoel expansion rate of 1,2-propanediol- or glycerol-exposed embryos, whereas exposure to 0.1% ethanol accelerate cavitation (p > 0.05). In a third experiment, morulae were exposed to 0.1% or 1.0% of each alcohol and were monitored for changes in intracellular calcium levels using the fluorescent indicator, fluo-3-acetoxymethyl ester. There was an immediate increase in intracellular calcium levels when morulae were treated with 1.0% ethanol or n-butanol, but only ethanol induced an increase (p < 0.05) in the level of intracellular calcium at 0.1%. These data suggest that ethanol is unique in its ability to accelerate embryogenesis and that the membrane disordering potency of ethanol does not directly underlie its effects on intracellular calcium release and the acceleration of preimplantation development.

Exposure of embryonic cells to alcohol: contrasting effects during preimplantation and postimplantation development

Alcohol is a known teratogen that causes a broad variety of developmental anomalies, including fetal growth retardation, craniofacial anomalies, and neurological disorders. The etiology of this multiple defect syndrome, known as fetal alcohol syndrome, has been studied in animal models that reproduce many of the attributes of the human disease. These studies show that ethanol is most teratogenic during organogenesis and development of the nervous system. The molecular basis of fetal alcohol effects has been further investigated using embryo and cell culture systems. Recent studies show that signal transduction pathways controlling cell proliferation are perturbed during ethanol exposure. Ethanol can induce the release of intracellular calcium stores, which stimulates the cell cycle, and it also up-regulates the expression of myc proteins associated with cell proliferation. Increased proliferation is advantageous during the preimplantation period, but ethanol interference with terminal differentiation events within developing tissues during organogenesis may underlie alcohol teratogenicity.

Cortical cell plasma membrane alterations after in vitro alcohol exposure: prevention by GM1 ganglioside

Using choleratoxin/antitoxin immunohistochemistry, this study examined the effects of in vitro alcohol exposure on the morphology of cell plasma membranes in mixed fetal rat cortical cultures, and assessed the neuroprotective effects of exogenous monosialoganglioside (GM1). Gangliosides are involved in critical biological functions, including maintenance of membrane integrity. Plasma membranes are directly affected by alcohol exposure through multiple mechanisms. Results indicate that exposure to alcohol altered plasma membrane morphology as assessed by staining for the surface distribution of membrane GM1. Pretreatment with endogenous GM1 ameliorated the alcohol-induced alterations.

[Experimental induction of abnormalities by the instillation of ethanol in embryonated eggs of chickens (Gallus gallus)]

The teratogenic effect of alcohol on chick embryos has been confirmed by many investigators. However, how this occurs is unknown. The aim of this study was to establish a teratogenic pattern of alcohol effects, on the first stages of development in avians. Fertilized eggs were infused through the air space of the shell on day 0, with ethanol in concentrations of 20%, 40% and 60%. The control group was infused with 0.1 ml of NaCl at 0.9%. At a second stage, the eggs were treated on the 4th day of incubation, using the same method. In both groups the eggs were removed on the 11th day of incubation. The teratological manifestations that appeared more frequently were evisceration, haemorrhagic embryos, oedema, cranial deformities, lack of eyes, and umbilical hernia, showing every embryo a clear reduction in size and body weight.

In utero ethanol exposure retards growth and alters morphology of cortical cultures: GM1 reverses effects

Ethanol, a developmental neurotoxin, alters plasma membranes' physicochemical properties affecting embryogenesis, cell migration, differentiation, and synaptogenesis. In a previous study using a model for fetal alcohol effects, GM1 ganglioside treatment was shown to reduce ethanol-induced accumulation of endogenous GM1 and fatty acid ethyl esters in rat fetuses. The present study was initiated to define further the in utero effects of ethanol and the capacity of GM1 treatment to ameliorate such effects. Wistar dams were exposed to ethanol (intragastrically) on gestation day (GD) 7 and GD8 and GD13 and GD14. GM1 ganglioside (10 mg/kg, im) was given 24 hr before ethanol administration. Cortical cultures were derived from GD15 and GD20 fetuses. GM1, which is highly localized on the cellular plasma membrane outer surface of CNS cells, was used as a marker molecule to assess cell integrity. Cholera toxin/antitoxin/fluorescence immunohistochemistry was used to localize GM1. Results indicate that the brief in utero exposure to ethanol affected cell growth and morphology. A marked retardation of cell development and arborization was observed as early as 24 hr after plating. Ethanol-exposed cells evidenced considerably altered GM1 localization. Such alterations likely reflect losses of membrane integrity. These in utero ethanol-induced pathologies are remarkably diminished in cultures derived from ethanol-exposed fetuses of dams treated with GM1.

Ethanol-induced teratogenesis: free radical damage as a possible mechanism

To investigate the possibility of a free radical mechanism for ethanol-induced teratogenesis, gestational day 8 mouse embryos were exposed for 6 hr in whole embryo culture to a teratogenic dosage of ethanol alone (500 mg%) or in conjunction with an antioxidant, superoxide dismutase (SOD; 300 U/ml). For subsequent analysis, some embryos were examined at the end of this 6-hr period, while others were removed to control medium and cultured for an additional time period. Ethanol exposure resulted in increased superoxide anion generation and increased lipid peroxidation (as noted 6 hr after initial ethanol exposure) and in excessive cell death (as noted 12 hr after initial exposure) in the embryos. Following a total of 36 hr in culture, a high incidence of malformation, including failure of the anterior neural tube to close in 63% of the ethanol-exposed embryos, was noted. The ethanol-induced superoxide anion generation, lipid peroxidation, excessive cell death, and dysmorphogenesis were diminished in embryos co-treated with SOD, suggesting that the teratogenicity of ethanol is mediated, at least in part, by free radical damage.

Maternal risk factors in fetal alcohol syndrome: provocative and permissive influences

We present an hypothesis integrating epidemiological, clinical case, and basic biomedical research to explain why only relatively few women who drink alcohol during pregnancy give birth to children with alcohol-related birth defects (ARBDs), in particular, Fetal Alcohol Syndrome (FAS). We argue that specific sociobehavioral risk factors, e.g., low socioeconomic status, are permissive for FAS in that they provide the context for increased vulnerability. We illustrate how these permissive factors are related to biological factors, e.g., decreased antioxidant status, which in conjunction with alcohol, provoke FAS/ARBDs in vulnerable fetuses. We propose an integrative heuristic model hypothesizing that these permissive and provocative factors increase the likelihood of FAS/ARBDs because they potentiate two related mechanisms of alcohol-induced teratogenesis, specifically, maternal/fetal hypoxia and free radical formation.

Alterations of mouse embryonic branchial nerves and ganglia induced by ethanol

An immunostaining technique using monoclonal antibodies to a neurofilament protein has allowed us to visualize defects in the development of cranial nerves and ganglia of 10 to 10.5 days mouse embryos following exposure to ethanol in whole embryo culture. Reference patterns for development of cranial nerves and ganglia of control mouse embryos explanted and examined when they had 25 to 34 pairs of somites were established. Additionally, control mouse embryos were grown in whole embryo culture for 48 h, with culture being initiated in embryos having 6 to 7 somite pairs. At the end of the culture period, only minor differences were observed between the control groups. An experimental group of embryos was cultured in the presence of increasing doses (1.6, 3.2, 4, and 4.8 g/l) of ethanol. Defects were observed in the development of the glossopharyngeal and vagus nerves. These abnormalities included absence of the dorsal root (superior ganglion) of IX, star-like shape of inferior ganglion IX, disorganization of the rootlets of nerve X and abnormal fibers between the two nerves and ganglia. These results suggest that the migration and patterning of neural crest cells derived from r6 and r7 may be particularly affected by ethanol. The results also demonstrate the usefulness of this approach in evaluating the susceptibility of the developing cranial nerves to toxicant exposure.

Cell death in rat and mouse embryos exposed to methanol in whole embryo culture

Methanol induces developmental toxicity in rats and mice producing exencephaly, cleft palate, cervical skeletal defects, reduced body weight, and increased embryo/fetal death. Exposure to methanol in whole embryo culture also induces developmental retardation, dysmorphogenesis, and embryo lethality. In the present study, cultured rat and mouse embryos were exposed to methanol and subsequently observed for morphological effects and increased cell death using modified Feulgen staining which allowed nuclei throughout the embryo to be examined in situ. Growth and developmental scores were reduced by methanol in both rat and mouse embryos and the mouse embryos were affected at lower concentrations when compared to the rat. Methanol increased cell death in specific regions of both rat and mouse embryos, including the forebrain, the visceral arches, otic and optic placodes. These regions form derivatives which manifest morphological abnormalities following exposure in vivo. Methanol did not increase cell death in the neuroepithelium or neural folds and neural tube defects cannot be explained by excess cell death. The results of this study suggest that increased cell death in specific regions of the exposed embryos has a role in producing cranial malformations, abnormalities of the eye and ear, and cleft palate.

Protective influence of zinc against the deleterious effects of ethanol in postimplantation rat embryos in vivo

Zinc is a cofactor for alcohol dehydrogenase, the ethanol metabolizing enzyme. Ethanol-induced zinc deficiency could decrease ethanol metabolism, resulting in an increase in circulating and tissue ethanol levels. This may cause retardation in embryonic growth and development. The influence of zinc supplementation on ethanol-induced embryopathy was studied by the simultaneous administration of ethanol and zinc to pregnant SD rats from gestational day 6 through 12. Ethanol was given in the form of a liquid diet and zinc was administered intraperitoneally. The ethanol group received the liquid ethanol diet, the ethanol+zinc group received the ethanol diet and zinc and the pair-fed control group was given an isocaloric control diet. Embryos were explanted from all groups on day 12 of gestation. Embryos of animals treated with ethanol alone exhibited a significantly higher rate of resorption and retarded embryonic growth and development compared to the pair-fed control group. The embryonic protein content, crown-rump length, the number of somites and embryonic morphological score were significantly reduced in the ethanol-treated group. In addition, serum zinc concentration also was lower. Compared to embryos from ethanol-treated animals, embryos from ethanol+zinc treated animals showed a significantly higher number of somites; cardiac development was more advanced and embryonic protein content was higher. These observations suggest that zinc supplementation of ethanol-treated pregnant rats may have some protective influence against the embryopathic effects of ethanol.

In vitro effect of S-adenosyl methionine on ethanol embryopathy in the rat

S-adenosyl methionine (SAM) is a universal methyl donor for biological systems. Chronic consumption of ethanol results in depletion of available SAM and reduces its biosynthesis in the transmethylation pathway. Administration of excess SAM may reduce the embryopathic effects of ethanol. The in-vitro effects of SAM on ethanol embryopathy was investigated by culturing 9.5 day old whole rat embryos for 48 hours in ethanol alone (Group II), 0.05 mM SAM (Group III), ethanol + 0.05 mM SAM (Group IV), ethanol + 0.1 mM SAM (Group V), ethanol + 1 mM SAM (Group VI), and in ethanol + 3 mM SAM (Group VII). In Group VII embryos, cardiovascular, nervous, auditory, visual, craniofacial and musculoskeletal systems were retarded in development; crown-rump length, yolk-sac diameter, as well as morphological scores, were reduced compared to those in embryos treated with ethanol alone (Group II). There were, however, significant differences between Group II and Group IV embryos with respect to crown-rump length, yolk sac diameter and somite number. The mean crown-rump length, yolk sac diameter and somite number in Group II were 2.3 +/- 0.2, 2.8 +/- 0.3 and 22.4 +/- 3.5 respectively, compared to 2.6 +/- 0.2, 3.1 +/- 0.2 and 25.3 +/- 3.1 in Group IV. These results suggest that simultaneous administration of S-adenosyl methionine and ethanol may protect against the embryopathic effects of ethanol.

Effect of maternal ethanol intake on fetal rabbit gastrointestinal development

Maternal ingestion of alcohol is believed to be one factor that greatly influences the development of intrauterine growth retardation (IUGR) and postnatal growth failure. The present study was undertaken to determine whether maternally ingested alcohol adversely affects fetal growth and intestinal mucosal function. Five time-mated New Zealand white rabbit does were given ethanol intravenously (ETH group) (30% vol/vol; 1.0 g/kg/d) on gestational days (GD) 15 through 29 (term, 31 days). Two other rabbits received the same dose of ethanol. Maternal, fetal, and amniotic fluid alcohol levels were measured on GD 24. Four control rabbits (SH group) received normal saline (25 mL, intravenously). At term, the animals were delivered by cesarean section and killed. Seventeen of the 42 ETH fetuses survived the study period (43%); all 24 SH fetuses survived. On GD 24, within 60 minutes after maternal ethanol infusion, the fetal blood alcohol concentration (BAC) increased to 153 +/- 1.97 mg/dL (v maternal, 179 +/- 1.75 mg/dL); the amniotic ethanol level increased to 46 +/- 1.32 mg/dL. Birth weight was lower in the ETH group (46.88 +/- 2.21 g) than in the SH group (55.78 +/- 1.80 g) (P < .01). Disaccharidase activity, an indicator of intestinal mucosal function, showed that lactase activity (per milligram of protein) was significantly lower in ETH fetuses (2.60 x 10(-2) +/- 0.22 UE/mg) than in SH fetuses (3.50 x 10(-2) +/- 0.25 UE/mg) (P = .01); maltase activity and protein content were not affected significantly. This report provides the first description of the adverse effects of maternal alcohol ingestion on the small intestinal mucosal function of the fetal rabbit.

Effects of chronic ethanol consumption on gestation and lactation in rats

Chronic consumption of ethanol during pregnancy and lactation may lead to abnormalities in the fetus or infant. A group of female Wistar rats was submitted to ethanol treatment over a period of a month. A pair-fed control group received sucrose solution isocaloric to ethanol and the control group received water "ad libitum." Afterward, the females were mated with males over a period of 20 days. At birth, each litter was maximized to eight pups and the remaining ones were decapitated to remove the fetal blood and brains. No significant difference was observed in fetal body and brain weight at birth. During lactation the ethanol and pair-fed groups gained less weight than the control group. After weaning, their weight became similar. Fetal blood glucose levels were decreased in the ethanol-treated group. One hundred percent of the pair-fed and control females delivered live fetuses at term and all survived; only 40% of the females in the ethanol group delivered, and one pup did not survive. Chronic ethanol treatment pointed to a possible reduction in the fertility. It seems likely that the change in body weight of ethanol-fed dams was caused by undernutrition.

In vitro assessment of individual and interactive effects of aromatic hydrocarbons on embryonic development of the rat

There have been reports of disruption of embryonic development following exposure of pregnant women to aromatic hydrocarbons. In the present study, the embryotoxicity of toluene, xylene, benzene, styrene, and its metabolite, styrene oxide, was evaluated using the in vitro culture of postimplantation rat embryos. Possible interactions between toluene, xylene, and benzene were also studied using mixtures of these solvents. The results of the study showed that toluene, xylene, benzene, and styrene all have a concentration-dependent embryotoxic effect on the developing rat embryo in vitro. Styrene was embryotoxic at a lower concentration (1.00 mumol/mL) than benzene (1.56 mumol/mL), toluene (2.25 mumol/mL), or xylene (1.89 mumol/mL). The metabolite of styrene, styrene oxide, was embryotoxic at a concentration (0.038 mumol/mL). more than 20 times less than the parent compound. There was no evidence of a synergistic interaction between toluene, xylene, and benzene in causing embryotoxicity; the solvents interacted in an additive manner. The embryos were exposed to the solvents for 40 h of the organogenic period. When the levels of solvents found to be embryotoxic in the present study are compared to blood levels in the human following industrial exposure or solvent abuse, it appears unlikely that the threshold blood levels for embryotoxicity would be exceeded in the workplace. However, the possibility that exposure to solvents earlier or later or throughout the entire organogenic period might result in a different conclusion cannot be excluded.

Effects of methanol on embryonic mouse palate in serum-free organ culture

Methanol has widespread applications in industry and manufacturing and is under consideration as an alternative automotive fuel. Human exposure to methanol would be expected to increase if applications expand in coming years. Methanol has been shown to be a reproductive and developmental toxicant in the rodent, producing cleft palate in the CD-1 mouse. Developmental toxicity has also been demonstrated in vitro for rat and mouse embryos in whole embryo culture. The present study examines the developmental toxicity of methanol in the palate using a serum-free organ culture model. Gestation day 12 CD-1 mouse embryos were dissected and mid-craniofacial tissues were cultured in BGJ medium at 37 degrees C for 4 days with medium changes at 24 hr intervals. Cultures were exposed to methanol from 0-20 mg/ml for 6 hr, 12 hr, 1 or 4 days. Some cultures were exposed to ethanol for 4 days at doses ranging from 0-15 mg/ml. All cultures were gassed with a 50% O2, 5% CO2, and 45% N2 upon addition of fresh medium and prior to the addition of alcohol. Following organ culture the craniofacial explants were examined for effects on morphology, fusion, proliferation, and growth. Incidence and completeness of palatal fusion decreased with increasing exposure. Depending on the concentration and duration of methanol exposure, the medial epithelium either degenerated completely or remained intact in unfused palates and either condition would interfere with fusion. Cellular proliferation appeared to be a specific and sensitive target for methanol as craniofacial tissues responded to methanol with reduction in total DNA content at an exposure that did not affect total protein. However, both DNA and protein decreased with increasing exposure to methanol. Incorporation of thymidine decreased significantly after 4 day exposure and autoradiography of 3H-thymidine (TdR) demonstrated exposure-dependent reduction in proliferation of palatal mesenchymal cells. Ethanol decreased fusion score, total protein, and DNA, but 3H-TdR/DNA was not significantly changed. In general the ethanol was more potent than methanol for inhibition of protein and DNA synthesis and palatal fusion. This study demonstrated that methanol can selectively affect specific sensitive cell populations and has effects on proliferation and cell fate.

Effect of ethanol on insulin-like growth factor-II release from fetal organs

This study examines the effect of ethanol (ETOH) exposure and nutrient restriction on the release of insulin-like growth factor (IGF)-II from 18- and 20-day explanted fetal organs. Fetuses were exposed to ETOH (E) in utero by feeding dams a 36% (calories derived from ETOH: 6.6% v/v) ETOH liquid diet. Control fetuses were offsprings of dams either pair-fed (P) a control liquid diet or ad libitum (A) fed a standard pelleted lab chow. Brain, heart, kidney, liver, lung, muscle, and placenta of fetuses from the same litter were pooled and explanted, and IGF-II concentration in explanted media was analyzed by radioimmunoassay. Maternal and fetal weights were determined during pregnancy and at sacrifice, respectively, to evaluate the influence of ETOH on growth. Both maternal and fetal weights were substantially reduced by ETOH on 18 and 20 days of gestation compared with both A and P controls. At 18 days of gestation, E fetuses (1.33 +/- 0.03 g) weighed less than either A (1.47 +/- 0.03 g) or P (1.54 +/- 0.04 g) fetuses. By 20 days, A mean fetal weight (4.19 +/- 0.23 g) was significantly greater than both P (3.74 +/- 0.06 g) and E (3.28 +/- 0.06 g) fetuses. IGF-II concentration in media from 18-day fetal explants was highest from E (brain, heart, liver, and placenta) and P tissues (kidney, lung, and muscle). IGF-II in media from A tissues (except placenta) was lower than both E and P levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenalectomy but not adrenal demedullation during pregnancy prevents the growth-retarding effects of fetal alcohol exposure

Growth retardation, both in the prenatal and the early neonatal period, is a consistent feature of fetal alcohol exposure, but the mechanism by which alcohol affects growth has not been elucidated. Because other stressors--such as maternal restraint and neonatal glucocorticoid treatment--can also affect growth, we examined the effect of ethanol on pup birthweight under two experimental conditions that altered maternal adrenal function. In the first study when dams were adrenalectomized and given low replacement doses of dexamethasone, the ethanol-exposed offspring of the adrenalectomized dams had birthweights similar to those of dams maintained on regular lab chow diets. In a second study, we found that maternal adrenal demedullation did not alter the reduction in birthweight produced by fetal ethanol exposure. The results suggest that the effects of ethanol on fetal growth may be mediated in part through ethanol-induced changes in the function of the maternal adrenal cortex.

Ethanol-induced insulin resistance suppresses the expression of embryonic ornithine decarboxylase activity

In utero exposure to ethanol is associated with significant increases in fetal morbidity and mortality as well as with behavioral and learning problems that appear later in life. Growth suppression of the developing child is the most frequent physical effect of ethanol exposure and is correlated with specific molecular changes within the developing organism. The present report suggests that embryonic ethanol exposure suppresses the normal developmental increase in ornithine decarboxylase (ODC) activity. The loss of ODC activity during the early stages of development is dose-dependent and is correlated with the degree of growth suppression. Because ODC is the rate-limiting step for the synthesis of the polyamines and thus appears to be a focal enzyme for the regulation of growth, we have investigated the biochemical consequences of an ethanol-induced inhibition of ODC activity. Using intact chick embryos as well as cultured embryonic tissue, these studies indicate that ethanol-induced changes in tissue putrescine content result in growth suppression because a single dose of exogenous putrescine blocked the growth suppression. In cultured tissue, ethanol exposure inhibited the ability of a known trophic factor (insulin) to induce ODC activity. The loss of insulin-inducible decarboxylase activity as a result of ethanol exposure was specific to ODC, but ethanol per se had no effect on ODC activity in vitro. The data suggest that exposure to ethanol results in a resistance of the embryonic tissue to the action of insulin and thereby disrupts the molecular path by which this mitogenic compound induces the expression of ODC enzymatic activity.

The effects of the timing of ethanol exposure during the brain growth spurt on the number of cerebellar Purkinje and granule cell nuclear profiles

Ethanol exposure during development is particularly deleterious to cerebellar Purkinje cells and granule cells, but the mechanism(s) underlying this sensitivity and the variables which affect it remain unknown. One important variable that has not been fully investigated, is the timing of the ethanol exposure. Ethanol exposure during the brain growth spurt causes a differential loss of Purkinje cells across the 10 lobules of the vermal cerebellum. However, whether or not changing the timing of the ethanol exposure during the brain growth spurt alters the extent and location of the loss of Purkinje cells within the cerebellar vermis has not been investigated. Moreover, the loss of cerebellar granule cells has been shown to parallel the loss of Purkinje cells, leading to the conclusion that the loss of granule cells occurred as a function of the loss of their targets, the Purkinje cells. The purpose of this study was to address both issues. Male rat pups were exposed to ethanol, via an artificial-rearing method, during one of the following 2-day time periods: postnatal days (PD) 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, or 12-13. Gastrostomy control (GC) and suckle control (SC) groups also were included. All pups were sacrificed on PD21. The number of Purkinje cell nuclear profiles from three vermal sections were counted in all groups, while the number of granule cell nuclear profiles in the ten lobules was estimated from pups in selected groups. No loss of Purkinje cells was observed in pups exposed to ethanol on PD7-8 or at any of the later exposure times. Additionally, among the three exposure groups in which significant Purkinje cell loss was observed (PD4-5, PD5-6 and PD6-7), seven lobules exhibited significant differences particularly between the PD4-5 and PD6-7 groups. The group with the greatest loss of Purkinje cells (PD4-5) also was the group with the greatest loss of granule cells. A significant loss of granule cells did not occur without a corresponding loss of Purkinje cells. The loss of both the Purkinje and granule cells was affected by the timing of the ethanol exposure, and that the extent and the location of Purkinje cell loss were extremely sensitive to the effects of the timing of the ethanol exposure.

Effects of prenatal alcohol exposure in mice: influence of an ADH inhibitor and a chronic inhalation study

In order to examine the effects of an alcohol dehydrogenase inhibitor on the embryotoxic effects of ethanol, pregnant ICR mice were treated with 100 mg/kg pyrazole prior to ethanol injection. I.p. treatment with 2 or 4 g/kg ethanol on day 7 of gestation increased the prenatal mortality rate and produced external and skeletal malformations in the offspring, and the embryotoxic effects were potentiated by pyrazole pretreatment, suggesting that ethanol rather than its metabolites is mainly responsible for the embryotoxicity. In the second experiment, we housed pregnant mice in an ethanol-vapor box for 3 or 6 days in order to examine the effects of prolonged low level exposure to alcohol. The maternal blood alcohol concentration was maintained approximately 0.03 mg/mL during inhalation. The inhalation treatment with ethanol increased the prenatal mortality rate, although teratogenicity was not shown.

Development of in vitro fertilized mouse embryos exposed to ethanol during the preimplantation period: accelerated embryogenesis at subtoxic levels

This study examined the effects of ethanol (EtOH) on mouse preimplantation development using an in vitro culture method. Embryos at the 1-cell, 2-cell, or 4-cell stage were exposed for 24 h to medium containing EtOH, then further cultured without EtOH to determine their ability to form blastocysts and to eventually hatch from the zona pellucida. EtOH exposure either arrested or enhanced normal development, depending on dose and embryonic stage of exposure. Exposure of 1-cell and 2-cell embryos to 1.6% (w/v) EtOH decreased blastocyst formation and hatching, and exposure of 1-cell embryos to 0.4% EtOH inhibited their development. At 0.1%, EtOH had an opposite effect, causing an increase in the percent blastocyst formation of treated 1-cell and 2-cell embryos. Neither inhibition nor stimulation of blastocyst formation occurred in 4-cell embryos exposed to 0.1-1.6% EtOH. Using an in vitro outgrowth model of implantation, embryos that reached the blastocyst stage were further tested for their ability to produce differentiated trophoblast cells. Blastocysts previously exposed to 0.1% EtOH during the 1-cell stage appeared to form adhesive trophoblasts earlier than control embryos, indicating that EtOH exposure can induce precocious differentiation of the trophoblast cells. The EtOH treated blastocysts contained significantly more cells than control blastocysts. These results indicate that EtOH can alter preimplantation development by either inhibiting or accelerating cell growth and differentiation.

Embryonic and fetal development: fundamental research

Much progress has been made over the past decades in the development of in vitro techniques for the assessment of chemically induced effects in embryonic and fetal development. In vitro assays have originally been developed to provide information on the mechanism of action of normal development, and have hence more adequately been used in fundamental research. These assays had to undergo extensive modification to be used in developmental toxicity testing. The present paper focuses on the rat whole embryo culture system, but also reviews modifications that were undertaken for the in vitro chick embryo system and the aggregate cultures of fetal rat brain cells. Today these tests cannot replace the existing in vivo developmental toxicity tests. They can, however, be used to screen chemicals for further development or further testing. In addition, these in vitro tests provide valuable information on the mechanisms of developmental toxicity and help to understand the relevancy of findings for humans. In vitro systems, combined with selected in vivo testing and pharmacokinetic investigations in animals and humans, can thus provide essential information for human risk assessment.

Effects of ethanol on glucose utilization by cultured mammalian embryos

We have previously observed correlations between placental glucose transfer and growth of fetuses of ethanol (EtOH)-fed and control rats. In the present study, whole mammalian embryos were used to define the interaction of glucose supply and the effects of EtOH on growth and differentiation. Rat embryos were cultured in 75% normal rat serum from day 9.5 to day 11.5 of gestation. EtOH produced dose-dependent reductions of embryo protein content (mean +/- SEM = 212 +/- 5, 171 +/- 11, 141 +/- 16, and 113 +/- 9 micrograms/embryo in the presence of 0, 25, 50, and 100 mM EtoH, respectively). Somite number was 25.7 +/- 0.3, 23.4 +/- 0.7, 21.8 +/- 0.7, and 21.1 +/- 0.4 under the same conditions. Exposure to ethanol during the first 24 hr in culture decreased embryo protein content to the same extent as exposure for the entire 48-hr culture period. After 46 hr in culture, control and ethanol-exposed embryos were incubated with 14C-glucose for 2 hr. Ethanol produced dose-dependent reductions of CO2 production, anabolic utilization, lactate release, and total glucose utilization. Glucose supplementation (300 mg/dl) significantly increased embryo protein content and each of these glucose utilization parameters. When glucose utilization was expressed relative to embryo protein content, incorporation of the label into embryonic tissues was significantly reduced by ethanol and increased by glucose supplementation. Embryo protein content correlated closely (r = 0.871, p less than 0.0001) with anabolic glucose utilization. Thus, ethanol directly affects embryo glucose utilization, both as an energy source and as a synthetic substrate, in addition to its effects on placental glucose transfer.

Effects of ethanol and acetaldehyde on rat embryos developing in vitro

Rat embryos were explanted on Days 9.5 or 10 of gestation and cultured for 48 to 30h, respectively, in rat serum containing 0, 3, 6, 9 mg/ml of Ethanol (Eth); 0, 10, 20 micrograms/ml of Acetaldehyde (Ach); 3 mg/ml Eth + 10 micrograms/ml Ach. At the end of the culture period the embryos were evaluated for vitality, and scored. Some of them were also examined histologically. Embryos exposed to Eth from Day 9.5 showed a dose-related growth retardation associated with a high frequency of malformations (open neural tube, heart defects, branchial arch hypoplasia). The exposure of 9.5-day embryos to 20 micrograms/ml Ach resulted in 100% embryolethality, whereas 10 micrograms/ml induced growth retardation and teratogenic effects. When 10-day embryos were exposed to 3 mg/ml Eth or 10 microliters/ml Ach no effects were observed, but the highest levels of Eth produced a moderate growth retardation and morphologic defects. Exposure to 20 micrograms/ml Ach induced hypoplasia of the first arch, but did not alter the score value. The histologic examination of these embryos revealed severe lesions at the level of the neuroepithelium and of the branchial mesenchyma. Similar effects were observed in embryos exposed simultaneously to 3 mg/ml Eth and 10 micrograms/ml Ach. These results should make us reevaluate the role of Ach in the Eth-induced embryopathies.

Teratogenic assessment of four solvents using the Frog Embryo Teratogenesis Assay--Xenopus (FETAX)

The Frog Embryo Teratogenesis Assay--Xenopus (FETAX) was used to assess the teratogenic potential of four solvents. Embryos of the South African clawed frog, Xenopus laevis, were exposed for 96 h to ethanol, dimethyl sulfoxide (DMSO), formamide or glycerol formal. Exposure groups were maintained using a static renewal system in which the exposure media were changed at 24-h intervals. Survival was monitored at 24-h intervals. Length, as an indicator of growth effects, and developmental malformations were determined at the end of the assay (96 h). Using this information, the 96-h LC50, the 96-h EC50 (Malformation), and the no observable effect levels (NOELs) for mortality, malformation and length were determined for each solvent. The teratogenic index [TI = 96-h LC50/96-h EC50 (Malformation)] also was calculated for each of the solvents. DMSO appeared to be the least toxic or teratogenic solvent examined, with a pooled LC50 of 1.92%, a pooled EC50 (Malformation) of 1.57% and TI values of 1.20 and 1.24 in replicate trials. Formamide appeared to be the most toxic solvent, with a pooled LC50 of 1.04%. Data trends suggested that ethanol was the most teratogenic solvent tested, with a pooled EC50 (Malformation) of 1.04% and TI values of 1.42 and 1.50. The results obtained in the present work for ethanol and DMSO were compared to previously published FETAX results for these two solvents. The present results are in close agreement with these results from other laboratories, thus providing further evidence supporting the interlaboratory reproducibility of FETAX results.

A tissue culture model for studying ethanol toxicity on embryonic heart cells

A tissue system in which fibroblasts and myocytes from chick embryonic hearts were separately maintained was used to study the toxicity of ethanol. To reproduce the teratogenic effects of acute, high concentrations of ethanol typical of "binge" drinking, an open tissue culture system was employed. With open cultures, the cells were initially exposed to peak alcohol levels for approximately 6 hr and were exposed to decreasing concentrations of ethanol for the remainder of each 24 hr period. After the first day of ethanol exposure, there was substantial cell loss in both fibroblast and myocyte cultures. Alcohol-induced cell loss was dose-dependent. Despite decreased cell density after the first day of ethanol exposure, the surviving cells differentiated into monolayers of fibroblasts or beating cardiac muscle fibers. However, both ethanol-exposed fibroblasts and myocytes appeared atrophic, that is, smaller and shrunken. Electrophoretic analysis or these ethanol-exposed fibroblast and myocyte cultures revealed specific reduction in the cellular contents of alpha-actinin, myosin, and actin. These decreases in cytoskeletal proteins may be responsible for the morphological abnormalities noted in these cells.

Craniofacial alterations in adult rats prenatally exposed to ethanol

The rat was studied to determine whether gestational exposure to moderate amounts of ethanol produces permanent craniofacial malformations. Pregnant Long-Evans rats were fed a liquid diet containing 35% ethanol-derived calories or an isocaloric liquid diet between gestation days 6 and 20. Various dimensions of skulls and mandibles from adult male offspring were measured. All measurements taken in the parasagittal and coronal planes were significantly smaller in the ethanol-exposed rats than in the offspring of pair-fed controls. None of the vertical measurements was significantly altered. This report demonstrates that gestational exposure to ethanol in rats, at doses which produce lasting behavioral effects, also produces a specific constellation of craniofacial dysmorphisms without concomitant decreases in body weight.

Ethanol consumption inhibits fetal DNA methylation in mice: implications for the fetal alcohol syndrome

Acute ethanol administration (3 g/kg twice a day) to pregnant mice, from the 9th thru the 11th day of gestation, resulted in hypomethylation of fetal deoxyribonucleic acid (DNA). Nuclei isolated from the fetuses of the ethanol-treated mice had lower levels of methylase activity relative to controls even in the presence of excess S-adenosylmethionine, which serves as the methyl donor for the enzyme DNA methyltransferase. Acetaldehyde, at concentrations as low as 3 to 10 microM, inhibited DNA methyltransferase activity in vitro. Since DNA methylation is thought to play an important role in the regulation of gene expression during embryogenesis, ethanol-associated alterations in fetal DNA methylation may contribute to the developmental abnormalities seen in the fetal alcohol syndrome.