Prenatal ethanol exposure in C57 mice: effects on pregnancy and offspring development

Sensory Motor Function Disturbances in Mice Prenatally Exposed to Low Dose of Ethanol: A Neurobehavioral Study in Postnatal and Adult Stages

Prenatal alcohol exposure (PAE) refers to fetal exposure to alcohol during pregnancy through placental barrier transfer from maternal blood. The postnatal outcomes of PAE differ among exposed individuals and range from overt (serious) alcohol-related behavioral and neurophysiological impairments to covert (silenced) symptoms. The aims of the present investigation were to assess the postnatal neurobehavioral disturbances, particularly, motor coordination and sensory-motor function in mice with PAE. Female mice with positive vaginal plugs were divided into three groups: group 1: Et + Pyr: received two i.p injections of ethanol (1 g/kg) followed by pyrazole (100 mg/kg). Group 2: Pyr: received an i.p injection of pyrazole (100 mg/kg). Group 3: C: of saline controls received, in equal volume, saline solution (NaCl 0.9%). After birth, mice pups were weighed and subjected to behavioral tests for motor function screening using the motor ambulation test, cliff aversion, surface righting, and negative geotaxis, while at the adult stage, mice were subjected to the open field, rotarod, parallel bars, and static rods tests. Our data show an obvious decrement of body weight from the first post-natal day (P1) and continues over the adult stage. This was accompanied by an obvious impaired sensory-motor function which was maintained even at the adult stage with alteration of the locomotor and coordination abilities. The current data demonstrate the powerful neurotoxic effect of prenatal ethanol exposure on the sensory-motor and coordination functions, leading to suppose possible structural and/or functional neuronal disturbances, particularly the locomotor network.

Adenylyl cylases 1 and 8 mediate select striatal-dependent behaviors and sensitivity to ethanol stimulation in the adolescent period following acute neonatal ethanol exposure

Neonatal alcohol exposure in rodents causes dramatic neurodegenerative effects throughout the developing nervous system, particularly in the striatum, acutely after exposure. These acute neurodegenerative effects are augmented in mice lacking adenylyl cyclases 1 and 8 (AC1/8) as neonatal mice with a genetic deletion of both AC isoforms (DKO) have increased vulnerability to ethanol-induced striatal neurotoxicity compared to wild type (WT) controls. While neonatal ethanol exposure is known to negatively impact cognitive behaviors, such as executive functioning and working memory in adolescent and adult animals, the threshold of ethanol exposure required to impinge upon developmental behaviors in mice has not been extensively examined. Therefore, the purpose of this study was to determine the behavioral effects of neonatal ethanol exposure using various striatal-dependent developmental benchmarks and to assess the impact of AC1/8 deletion on this developmental progression. WT and DKO mice were treated with 2.5 g/kg ethanol or saline on postnatal day (P)6 and later subjected to the wire suspension, negative geotaxis, postural reflex, grid hang, tail suspension and accelerating rotarod tests at various time points. At P30, mice were evaluated for their hypnotic responses to 4.0 g/kg ethanol by using the loss of righting reflex assay and ethanol-induced stimulation of locomotor activity after 2.0 g/kg ethanol. Ethanol exposure significantly impaired DKO performance in the negative geotaxis test while genetic deletion of AC1/8 alone increased grid hang time and decreased immobility time in the tail suspension test with a concomitant increase in hindlimb clasping behavior. Locomotor stimulation was significantly increased in animals that received ethanol as neonates, peaking significantly in ethanol-treated DKO mice compared to ethanol-treated WT controls, while sedation duration following high-dose ethanol challenge was unaffected. These data indicate that the maturational parameters examined in the current study may not be sensitive enough to detect effects of a single ethanol exposure during the brain growth spurt period. Genetic deletion of AC1/8 reveals a role for these cylases in attenuating ethanol-induced behavioral effects in the neonatally-exposed adolescent.

Neurotrophic peptides, ADNF-9 and NAP, prevent alcohol-induced apoptosis at midgestation in fetal brains of C57BL/6 mouse

Prenatal alcohol exposure is known to induce fetal brain growth deficits at different embryonic stages. We focused this study on investigating the neuroprotective effects against alcohol-induced apoptosis at midgestation using activity-dependent neurotrophic factor (ADNF)-9, a peptide (SALLRSIPA) derived from activity-dependent neurotrophic factor, and NAP, a peptide (NAPVSIPQ) derived from activity-dependent neuroprotective protein. We used an established fetal alcohol exposure mouse model. On embryonic day 7 (E7), weight-matched pregnant females were assigned to the following groups: (1) ethanol liquid diet (ALC) group with 25 % (4.49 %, v/v) ethanol-derived calories, (2) pair-fed (PF) control group, (3) ALC combined with i.p. injections (1.5 mg/kg) of ADNF-9 (ALC/ADNF-9) group, (4) ALC combined with i.p. injections (1.5 mg/kg) of NAP (ALC/NAP) group, (5) PF liquid diet combined with i.p. injections of ADNF-9 (PF/ADNF-9) group, and (6) PF liquid diet combined with i.p. injections of NAP (PF/NAP) group. On day 15 (E15), fetal brains were collected, weighed, and assayed for TdT-mediated dUTP nick end labeling (TUNEL) staining. ADNF-9 or NAP was administered daily from E7 to E15 alongside PF or ALC liquid diet exposure. Our results show that NAP and ADNF-9 significantly prevented alcohol-induced weight reduction of fetal brains. Apoptosis was determined by TUNEL staining; NAP or ADNF-9 administration alongside alcohol exposure significantly prevented alcohol-induced increase in TUNEL-positive cells in primordium of the cingulate cortex and ganglionic eminence. These findings may pave the path toward potential therapeutics against alcohol intoxication during pregnancy stages.

Neuroprotective peptide ADNF-9 in fetal brain of C57BL/6 mice exposed prenatally to alcohol

Background

A derived peptide from activity-dependent neurotrophic factor (ADNF-9) has been shown to be neuroprotective in the fetal alcohol exposure model. We investigated the neuroprotective effects of ADNF-9 against alcohol-induced apoptosis using TUNEL staining. We further characterize in this study the proteomic architecture underlying the role of ADNF-9 against ethanol teratogenesis during early fetal brain development using liquid chromatography in conjunction with tandem mass spectrometry (LC-MS/MS).

Methods

Pregnant C57BL/6 mice were exposed from embryonic days 7-13 (E7-E13) to a 25% ethanol-derived calorie [25% EDC, Alcohol (ALC)] diet, a 25% EDC diet simultaneously administered i.p. ADNF-9 (ALC/ADNF-9), or a pair-fed (PF) liquid diet. At E13, fetal brains were collected from 5 dams from each group, weighed, and frozen for LC-MS/MS procedure. Other fetal brains were fixed for TUNEL staining.

Results

Administration of ADNF-9 prevented alcohol-induced reduction in fetal brain weight and alcohol-induced increases in cell death. Moreover, individual fetal brains were analyzed by LC-MS/MS. Statistical differences in the amounts of proteins between the ALC and ALC/ADNF-9 groups resulted in a distinct data-clustering. Significant upregulation of several important proteins involved in brain development were found in the ALC/ADNF-9 group as compared to the ALC group.

Conclusion

These findings provide information on potential mechanisms underlying the neuroprotective effects of ADNF-9 in the fetal alcohol exposure model.

Postnatal growth restriction and gene expression changes in a mouse model of fetal alcohol syndrome

Growth restriction, craniofacial dysmorphology, and central nervous system defects are the main diagnostic features of fetal alcohol syndrome. Studies in humans and mice have reported that the growth restriction can be prenatal or postnatal, but the underlying mechanisms remain unknown.We recently described a mouse model of moderate gestational ethanol exposure that produces measurable phenotypes in line with fetal alcohol syndrome (e.g., craniofacial changes and growth restriction in adolescent mice). In this study, we characterize in detail the growth restriction phenotype by measuring body weight at gestational day 16.5, cross-fostering from birth to weaning, and by extending our observations into adulthood. Furthermore, in an attempt to unravel the molecular events contributing to the growth phenotype, we have compared gene expression patterns in the liver and kidney of nonfostered, ethanol-exposed and control mice at postnatal day 28.We find that the ethanol-induced growth phenotype is not detectable prior to birth, but is present at weaning, even in mice that have been cross-fostered to unexposed dams. This finding suggests a postnatal growth restriction phenotype that is not due to deficient postpartum care by dams that drank ethanol, but rather a physiologic result of ethanol exposure in utero. We also find that, despite some catch-up growth after 5 weeks of age, the effect extends into adulthood, which is consistent with longitudinal studies in humans.Genome-wide gene expression analysis revealed interesting ethanol-induced changes in the liver, including genes involved in the metabolism of exogenous and endogenous compounds, iron homeostasis, and lipid metabolism.

Differential expression of proteins in fetal brains of alcohol-treated prenatally C57BL/6 mice: a proteomic investigation

Alcohol is known to impede the growth of the central nervous system and to induce neurodegeneration through cellular apoptosis. We have previously shown that moderate prenatal alcohol exposure results in brain defects at different stages of development. In this study, we further characterize the proteomic architecture underlying ethanol teratogenesis during early fetal brain development using chromatography in conjunction with a LC-MS/MS system. Pregnant C57BL/6 mice were exposed from embryonic day 7 (E7) to E13 with either a 25% ethanol derived calorie or pair-fed liquid diets. At E13, fetal brains were collected from five dams for each group. Individual brains were homogenized and the extracted proteins were then tryptically digested and analyzed by LC-MS/MS. Label-free quantitative proteomic analyses were performed on proteomes extracted from fetal brains of both alcohol-treated (ALC) and pair-fed groups. These analyses demonstrated that prenatal alcohol exposure induced significant downregulation (p<0.001) of the expression of mitochondrial enzymes including ADP/ATP translocase 1, ATP synthase subunit alpha and ubiquinol-cytochrome-c reductases. In addition, mitochondrial carrier homolog 1, which plays a role in apoptosis, was significantly downregulated (p<0.001) in the ALC group. Moreover, among the cytosolic proteins that were significantly downregulated (p<0.001) are Bcl-2, 14-3-3 protein and calmodulin. Significant downregulation (p<0.001) of proteins that are critical for fetal brain development was observed such as prohibitin and neuronal migration protein doublecortin. These findings provide information about possible mechanisms underlying the effects of prenatal alcohol exposure during early embryonic stage.

Alteration of selective neurotransmitters in fetal brains of prenatally alcohol-treated C57BL/6 mice: quantitative analysis using liquid chromatography/tandem mass spectrometry

We previously demonstrated that prenatal alcohol exposure results in brain defects at different embryonic stages. This study is aimed at characterizing the influence of prenatal alcohol exposure on the levels of several neurotransmitters at early embryonic stage 13 (E13). Pregnant C57BL/6 mice were exposed to either a 25% ethanol derived calorie diet (ALC) or pair-fed (PF) liquid diet from E7 to E13. At E13, fetal brains were collected from dams of the ALC and PF groups. Liquid chromatography/tandem mass spectrometry (LC-MS) was then used to evaluate neurotransmitter levels. This approach involved the use of an LC column in conjunction with multiple-reaction monitoring mass spectrometry. Quantitative analyses of catecholamines, idolamine, and amino acid neurotransmitters revealed significant reductions in the levels of dopamine (p=0.004), norepinephrine (p=0.0009), epinephrine (p=0.0002), serotonin (p=0.004), and GABA (p=0.002) in the ALC group compared to the PF group. However, there was no significant change in the levels of glutamate in E13 fetal brains. These findings demonstrate that prenatal alcohol exposure reduces the concentrations of some catecholamines, idolamine, and amino acid neurotransmitters in E13 fetal brains. This study suggests that alterations of selective neurotransmitters may be the cause of abnormalities in brain function and behavior found in fetal alcohol spectrum disorders.

A novel peptide, colivelin, prevents alcohol-induced apoptosis in fetal brain of C57BL/6 mice: signaling pathway investigations

Fetal alcohol exposure is known to induce cell death through apoptosis. We found that colivelin (CLN), a novel peptide with the sequence SALLRSIPAPAGASRLLLLTGEIDLP, prevents this apoptosis. Our initial experiment revealed that CLN enhanced the viability of primary cortical neurons exposed to alcohol. We then used a mouse model of fetal alcohol exposure to identify the intracellular mechanisms underlying these neuroprotective effects. On embryonic day 7 (E7), weight-matched pregnant females were assigned to the following groups: (1) ethanol liquid diet 25% (4.49% v/v) ethanol derived calories; (2) pair-fed control; (3) normal chow; (4) ethanol liquid diet combined with administration (i.p.) of CLN (20 microg/20 g body weight); and (5) pair-fed combined with administration (i.p.) of CLN (20 microg/20 g body weight). On E13, fetal brains were collected and assayed for TdT-mediated dUTP nick end labeling staining, caspase-3 colorimetric assay, enzyme-linked immunosorbent assay, and Meso scale discovery electrochemiluminescence. CLN blocked the alcohol-induced decline in brain weight and prevented alcohol-induced: apoptosis, activation of caspase-3 and increases of cytosolic cytochrome c, and decreases of mitochondrial cytochrome c Analysis of proteins in the upstream signaling pathway revealed that CLN down-regulated the phosphorylation of the c-Jun N-terminal kinase. Moreover, CLN prevented alcohol-induced reduction in phosphorylation of BAD protein. Thus, CLN appears to act directly on upstream signaling proteins to prevent alcohol-induced apoptosis. Further assessment of these proteins and their signaling mechanisms is likely to enhance development of neuroprotective therapies.

Using drinking in the dark to model prenatal binge-like exposure to ethanol in C57BL/6J mice

Animal models of prenatal ethanol exposure are necessary to more fully understand the effects of ethanol on the developing embryo/fetus. However, most models employ procedures that may produce additional maternal stress beyond that produced by ethanol alone. We employed a daily limited-access ethanol intake model called Drinking in the Dark (DID) to assess the effects of voluntary maternal binge-like ethanol intake on the developing mouse. Evidence suggests that binge exposure may be particularly harmful to the embryo/fetus, perhaps due to the relatively higher blood ethanol concentrations achieved. Pregnant females had mean daily ethanol intakes ranging from 4.2 to 6.4 g/kg ethanol over gestation, producing blood ethanol concentrations ranging from 115 to 182 mg/dL. This level of ethanol intake produced behavioral alterations among adolescent offspring that disappeared by adulthood, including altered sensitivity to ethanol's hypnotic actions. The DID model may provide a useful tool for studying the effects of prenatal ethanol exposure in mice.

Activity-dependent neuroprotective protein-derived peptide, NAP, preventing alcohol-induced apoptosis in fetal brain of C57BL/6 mouse

Possible prevention of the effects of prenatal alcohol exposure has been investigated using peptides that were previously shown to be involved in neuroprotection both in vitro and in vivo. I focused in this study on investigating the neuroprotective effects of one of these peptides with regard to the determination of the downstream signaling pathways involved in neuroprotection. This peptide with the sequence NAPVSIPQ, known as NAP, a fragment of activity-dependent neuroprotective protein, demonstrated a potent protective effect against oxidative stress associated with alcohol exposure. On embryonic day 7 (E7), weight-matched C57BL/6 pregnant females were assigned the following groups: (1) Ethanol liquid diet group (ALC) 25% (4.49%, v/v) ethano-derived calories, (2) Pair-fed (PF) control group (3) Chow control group, (4) treatment groups with alcohol alongside i.p. injections of d-NAP (ALC/d-NAP, 20 or 30 microg/20 g body weight), (5) PF/d-NAP control group. On E13, fetal brains were collected and assayed for TdT-mediated dUTP nick end labeling (TUNEL) staining, caspase-3 colorimetric assay and ELISA for cytochrome c detection. My results show that NAP significantly prevented alcohol-induced weight reduction of the fetal brain. Apoptosis was determined by TUNEL staining; NAP administration significantly prevented alcohol-induced increases in TUNEL-positive cells in primordium cingulate cortex and basal ganglia eminence. The investigation of downstream signaling pathways involving NAP neuroprotection revealed that this peptide significantly prevented alcohol-induced increase in the concentrations of caspase-3 in E13 fetal brains. Moreover, ELISA for cytochrome c shows that NAP significantly prevented both alcohol-induced increases in the level of cytosolic cytochrome c and alcohol-induced decreases in the level of mitochondrial cytochrome c. These data provide an understanding of NAP intracellular target, and the downstream mechanisms of action that will pave a path toward potential therapeutics against alcohol intoxication during prenatal stages.

No effect of prenatal alcohol exposure on activity in three inbred strains of mice

AIMS

Prenatal exposure to alcohol can have adverse effects on the developing fetus. Two of the hallmarks of children exposed to alcohol prenatally are attention deficits and hyperactivity. While hyperactivity has been observed in rats following prenatal ethanol exposure, few studies have examined these effects in mice. The present study investigated the effects of prenatal ethanol exposure on activity in mice from three inbred strains: C57BL/6 (B6), Inbred Long Sleep (ILS) and Inbred Short Sleep (ISS).

METHODS

On Days 7 through 18 of gestation, mice were intragastrically intubated twice daily with either 3.0 g/kg ethanol (E) or an isocaloric amount of maltose-dextrin (MD); non-intubated control (NIC) litters were also generated. Offspring activity was monitored at 30, 60, 90 and 150 days of age.

RESULTS

While results showed no effects of prenatal ethanol exposure on any measures of activity, we did observe differences in baseline activity among the strains. ISS mice were more active than B6 and ILS for all activity measures except stereotypy; B6 mice had higher measures of stereotypy than ILS and ISS. Younger mice were more active than older mice. The only sex effects were on measures of stereotypy, where males had higher scores.

CONCLUSIONS

Mice are an excellent organism to study genetic influences on many phenotypes. However, our study and others have shown few effects of prenatal ethanol exposure on behavior in mice. It appears as if the prenatal period in mice, corresponding to organogenesis, is not a sensitive period for producing behavioral deficits following ethanol exposure. It is likely that the first 2 weeks postnatally, corresponding to the brain growth spurt, are more sensitive for producing behavioral effects.

Low-level human equivalent gestational lead exposure produces sex-specific motor and coordination abnormalities and late-onset obesity in year-old mice

BACKGROUND

Low-level developmental lead exposure is linked to cognitive and neurological disorders in children. However, the long-term effects of gestational lead exposure (GLE) have received little attention.

OBJECTIVES

Our goals were to establish a murine model of human equivalent GLE and to determine dose-response effects on body weight, motor functions, and dopamine neurochemistry in year-old offspring.

METHODS

We exposed female C57BL/6 mice to water containing 0, 27 (low), 55 (moderate), or 109 ppm (high) of lead from 2 weeks prior to mating, throughout gestation, and until postnatal day 10 (PN10). Maternal and litter measures, blood lead concentrations ([BPb]), and body weights were obtained throughout the experiment. Locomotor behavior in the absence and presence of amphetamine, running wheel activity, rotarod test, and dopamine utilization were examined in year-old mice.

RESULTS

Peak [BPb] were < 1, < or = 10, 24-27, and 33-42 microg/dL in control, low-, moderate- and high-dose GLE groups at PN0-10, respectively. Year-old male but not female GLE mice exhibited late-onset obesity. Similarly, we observed male-specific decreased spontaneous motor activity, increased amphetamine-induced motor activity, and decreased rotarod performance in year-old GLE mice. Levels of dopamine and its major metabolite were altered in year-old male mice, although only forebrain utilization increased. GLE-induced alterations were consistently larger in low-dose GLE mice.

CONCLUSIONS

Our novel results show that GLE produced permanent male-specific deficits. The nonmonotonic dose-dependent responses showed that low-level GLE produced the most adverse effects. These data reinforce the idea that lifetime measures of dose-response toxicant exposure should be a component of the neurotoxic risk assessment process.

Maternal oral intake mouse model for fetal alcohol spectrum disorders: ocular defects as a measure of effect

BACKGROUND

This work was conducted in an effort to establish an oral intake model system in which the effects of ethanol insult that occur during early stages of embryogenesis can be easily examined and in which agents that may modulate ethanol's teratogenicity can be readily tested in vivo. The model system described utilizes the alcohol deprivation effect to obtain teratogenic levels of maternal ethanol intake on days 7 and 8 of pregnancy in C57Bl/6J mice. Ocular defects including microphthalmia and uveal coloboma, which have previously been shown to result from ethanol administered by gavage or via intraperitoneal injection on these days, served as the developmental end point for this study. The ocular defects are readily identifiable and their degree of severity is expected to correlate with concurrently developing defects of the central nervous system (CNS).

METHODS

Female C57Bl/6J mice were maintained on an ethanol-containing (4.8% v/v) liquid diet for 14 days and then mated during a subsequent abstinence period. Mice were then reexposed to ethanol on days 7 and 8 of pregnancy only. Control as well as ethanol-exposed dams were killed on their 14th day of pregnancy. Fetuses were then weighed, measured for crown rump length, photographed, and analyzed for ocular abnormalities. Globe size, palpebral fissure length, and pupil size and shape were noted for both the right and left eyes of all fetuses and informative comparisons were made.

RESULTS

This exposure paradigm resulted in peak maternal blood alcohol concentrations that ranged from 170 to 220 mg/dL on gestational day (GD) 8. Compared with the GD 14 fetuses from the normal control group, the pair-fed, acquisition controls, as well as the ethanol-exposed fetuses, were developmentally delayed and had reduced weights. Confirming previous studies, comparison of similarly staged control and treated GD 8 embryos illustrated reductions in the size of the forebrain in the latter. Subsequent ocular malformations were noted in 33% of the right eyes and 25% of the left eyes of the 103 GD 14 ethanol-exposed fetuses examined. This incidence of defects is twice that observed in the control groups. Additionally, it was found that the palpebral fissure length is directly correlated with globe size.

CONCLUSIONS

The high incidence of readily identifiable ocular malformations produced by oral ethanol intake in this model and their relevance to human fetal alcohol spectrum disorders (FASD) makes this an excellent system for utilization in experiments involving factors administered to the embryo that might alter ethanol's teratogenic effects. Additionally, the fact that early ethanol insult yields ocular and forebrain abnormalities that are developmentally associated allows efficient specimen selection for subsequent detailed analyses of CNS effects in this in vivo mammalian FASD model.

Antioxidative Treatment Diminishes Ethanol-Induced Congenital Malformations in the Rat

BACKGROUND

Intrauterine exposure to ethanol causes embryonic and fetal growth retardation and maldevelopment. Oxidative stress in mother and offspring has been suggested to be part of the teratogenic mechanism, and supplementation of antioxidative agents to the pregnant women may therefore be of value in future prophylactic treatment regimen. There is a need for in vivo experimental work in this field, and in the present study, our aim was to investigate whether chronic ethanol consumption induced congenital malformations in rats and, if so, whether dietary supplementation of vitamin E (alpha-tocopherol) diminished such maldevelopment.

METHODS

Female Sprague-Dawley rats were given drinking water containing 20% ethanol and half of these received food containing 5% vitamin E. Non-ethanol-exposed female rats, with or without vitamin E treatment, served as controls. The pregnancy was interrupted on gestational day 20 when the offspring was evaluated morphologically and fetal hepatic 8-iso-PGF(2alpha) levels were measured to assess the degree of fetal oxidative stress.

RESULTS

Exposure to 20% ethanol increased maternal blood ethanol to 1.5 promille and increased resorption and malformation rates in the offspring. Maternal vitamin E treatment did not affect blood ethanol levels, but normalized fetal development. The fetal hepatic levels of 8-iso-PGF(2alpha) were increased in the ethanol-exposed group and normalized by vitamin E treatment of the mother.

CONCLUSIONS

Ethanol exposure disturbs embryogenesis partly by enhanced oxidative stress, and the adverse effects can be ameliorated by antioxidative treatment.

Moderate alcohol exposure compromises neural tube midline development in prenatal brain

We previously reported that fetal alcohol treatment compromised the development of the midline raphe and the serotonin neurons contained in it. In this study, we report that the timely development of midline neural tissue during neural tube formation is sensitive to alcohol exposure. Pregnant dams were treated from embryonic day 7 (E7, prior to neurulation) or E8.5 (at neurulation) with the following diets: (a) alcohol (ALC), given as either a 20% or 25% ethanol-derived calorie (EDC) liquid diet, or (b) isocaloric liquid diet pair-fed (PF), or (c) standard rat chow (Chow). Fetal brains from each group were examined on E13, E15, or E18. Neural tube development was compromised as a result of alcohol exposure in the following ways: (1) approximately 60% of embryos at E13 and 20% at E15 showed perforation of the floor plate in the diencephalic vesicle, (2) although completely closed at E13, 70-80% of embryos failed to complete the formation of neural tissue at the roof as the alcohol exposure continued to E15, and (3) 60-80% of embryos show delayed 'occlusion' of the ventral canal by newly formed nestin-positive neuroepithelial cells and S100beta-positive glia in the brainstem of E15. The compromised (incomplete) neural tube midline (cNTM) occurred near the ventricles at E13 and E15, but was later completed at E18. In all cases, the cNTM was accompanied by an enlarged ventricle, and dose-dependent brain weight reduction. The midline of the neural tube at the roof and floor plates is known to mediate timely trophic induction for neural differentiation. Prenatal midline deficits also have the potential to affect the development of midline neurons such as raphe, septal nuclei, and the timely crossing of commissural fibers. The results of the liquid diet alcohol exposure paradigm suggest it is more a model for Alcohol-Related Neurodevelopmental Disorder (ARND) featuring neuropsychiatric disorders than for full-blown fetal alcohol syndrome (FAS) with noticeable facial dysmorphogenesis and gross brain retardation.

Deviations in brain early serotonergic development as a result of fetal alcohol exposure

Serotonin (5-HT) has specific roles not only as a transmitter but also as a signal for differentiation. We recently found that alcohol drinking during pregnancy resulted in incomplete-neural-tube-fusion which hindered the development of midline cells such as 5-HT neurons in mice. We now report that, at the birth of 5-HT neurons (E11), the 5-HT immunoreative (5-HT-im) neurons are often found missing medial projecting fibers towards ventricle in the Alcohol treated group (ALC) as compared with pair-fed (PF) and Chow-fed groups (Chow) in mice. At E13, there are fewer 5-HT-im neurons in either dorsal or median raphe of ALC as compared with PF or Chow; furthermore, neurite outgrowth and migration of the 5-HT neurons are also compromised with alcohol exposure. We, thus, demonstrated that fetal alcohol exposure compromised 5-HT development as early as at the 5-HT neuron birth. Since 5-HT is a signal for development of many forebrain neurons, the deviation of 5-HT in early life may have consequences on brain development that extend beyond those seen in the 5-HT system.

Prenatal alcohol exposure retards the migration and development of serotonin neurons in fetal C57BL mice

Incomplete neural tube fusion (iNTF), induced by alcohol, in midline floor and roof plates was found in our recent study. In this study, serotonin (5-HT) neurons, known to be born entirely in the midline raphe at brainstem, were examined during their development with fetal alcohol exposure. Weight-matched C57BL mice pregnant dams were divided into three groups on E8: one received ethanol via a chocolate Sustacal liquid diet providing 20% ethanol-derived calories as the sole source of nutrients (ALC); the second received an isocaloric Sustacal liquid diet and was pair-fed to individual dams in the ethanol-fed group (PF); the third was fed ad lib rat chow (Chow). Fetal brains were obtained on E15 and were processed for immunostaining of 5-HT and its trophic factor, S100 beta. The ascending 5-HT neurons, in normal development, appear bilaterally near midline on E12, and by E15, as seen in chow and PF groups, migrate from the midline germinal zone laterally and dorsally to their final position with rich fibers. In contrast, in the E15 ALC group, many 5-HT-im neurons were found remaining in the midline germinal region or had migrated, but with under-differentiated, sparse fibers. There were 20--30% fewer 5-HT-im neurons in ALC as compared to PF and Chow. In addition, the number of S100 beta cells was less in ALC as compared with PF and Chow groups. No difference was found between PF and Chow in number of 5-HT-im or S100 beta-im cells. The 5-HT neurons found compromised in migration and differentiation may, in part, stem from failure of access to floor plate or midline tissue induction and the insufficient support by S100 beta. As 5-HT neurons have been implicated for signaling brain maturation, fewer 5-HT neurons may have lasting effects on the development of brain or, if persistent in the adult, profoundly affect adult brain function.

Teratogenic actions of ethanol in the mouse: a minireview

The deleterious effects of prenatal ethanol exposure have been extensively documented in clinical and experimental studies. This paper provides an overview of work conducted with mice to examine the myriad of adverse consequences that result from embryonic/fetal exposure to ethanol. All of the hallmark features of the clinical fetal alcohol syndrome have been demonstrated in mice, including prenatal and postnatal growth retardation, structural malformations and behavioral abnormalities associated with central nervous system dysfunction. As expected, the severity and profile of effects is related to both dosage level and timing of exposure. In addition, these effects have been demonstrated following acute and chronic exposure, with a variety of routes of administration employed. Furthermore, a number of strains have been used in these studies and the variant response (susceptibility) to the teratogenic actions of ethanol exhibited among different mouse strains support the notion that genetic factors govern, at least in part, vulnerability to these effects of ethanol. More recent studies using mouse models have focused on examining potential mechanisms underlying the full spectrum of ethanol's teratogenic actions.

Effects of prenatal ethanol exposure on dopamine systems in C57BL/6J mice

Young rats prenatally exposed to ethanol exhibit heightened responses to dopaminergie (DA) drugs, altered brain concentrations of dopamine, and its metabolite dihydroxyphenylacetic acid (DOPAC), and transient reductions in DA receptor binding. Adult mice exposed to ethanol prenatally also exhibit increased responses to DA drugs; however, brain concentrations of DA and DOPAC are unaltered. The effects of prenatal ethanol exposure on DA or DOPAC concentrations in young mice or on DA receptor binding in mice of any age are unknown. Therefore, to determine if the different effects of prenatal ethanol exposure on rats and mice are due to age at time of testing or species, we determined its effects on DA concentrations and turnover in young mice under conditions previously reported for adult offspring and on DA D1 and D2 receptor binding in both young and adult offspring. Consistent with our previous report for adult offspring, prenatal ethanol exposure did not alter DA concentrations or turnover. The treatment did, however, diminish periadolescent growth as previously reported and produced a transient increase in DA D1, but not DA D2 receptor binding. DA receptor binding was not altered in adult offspring. Although unrelated to prenatal ethanol exposure, the sexes differed on all of the DA measures. Combined with previous reports, the present study suggests that species rather than age is more likely to account for the different effects of prenatal ethanol exposure on DA systems, and that sex differences in DA systems should be further examined.

Perinatal maternal ethanol effects on pregnant mice and on offspring viability and growth: influences of exposure time and weaning diet

C57BL/6 mice were maintained on liquid diets containing 27.5% ethanol-derived calories beginning on gestational day 12. For one group, the liquid diet was replaced with laboratory chow on the morning of gestational day 18, approximately 24 hr before delivery. For a second group, the diet was continued for 7 days postnatally. Two additional groups were pair-fed isocaloric sucrose diets, and a final group was maintained on normal laboratory chow. The mice consumed sufficient amounts of diet to provide near 30 g ethanol/kg/day during pregnancy and slightly greater amounts during the first postpartum week. The ethanol diet produced no maternal deaths and did not alter weight gain during gestational days 12-17 of pregnancy. The results confirmed previous reports that dietary ethanol exposure under conditions that have rather minor effects on the pregnant mouse can substantially affect the fetus. As previously reported, when exposure was terminated 24 hr before delivery, neonatal mortality was elevated by approximately 30%, but birth weight was not altered. When the diet was extended into the lactation period, mortality was delayed but not reduced, possibly by reducing the severity of ethanol withdrawal. Birthweight was reduced by 10% when exposure continued until birth, suggesting that low birthweights for fetal ethanol-exposed (FEE) mice can be eliminated by terminating exposure approximately 24 hr before delivery. As in previous reports, FEE mice with normal birthweights had an attenuated preadolescent growth spurt, suggesting that low birthweights and attenuated postnatal growth are likely mediated by different mechanisms.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol, marijuana, and tobacco: effects of prenatal exposure on offspring growth and morphology at age six

Little is known about the long-term effects of prenatal exposure to alcohol. There are even fewer reports on the longitudinal effects of exposure to either marijuana or tobacco during pregnancy. This study is on the 6-year follow-up of 668 children enrolled in the Maternal Health Practices and Child Development Project. Mothers were interviewed at the 4th and 7th months of pregnancy, and mothers and children were evaluated at delivery, 8, and 18 months, and 3 and 6 years postpartum. At 6 years of age, children who were exposed to alcohol prenatally were significantly smaller in weight, height, head circumference, and palpebral fissure width. These effects on size were mediated by the effect of prenatal alcohol exposure on the offspring at 8 months. Prenatal alcohol exposure was also significantly associated with maternal reports of the child's appetite at 6 years. There were no effects of prenatal marijuana or tobacco exposure on growth when the children were age 6. There were also no significant relationships between prenatal exposure to alcohol, marijuana, or tobacco and the rate of morphologic anomalies, including the features of the fetal alcohol syndrome.

Prenatal ethanol effects and dopamine systems of adult C57 male mice

Behavioral, pharmacological, and neurochemical studies indicate that prenatal ethanol exposure can alter dopamine (DA) systems of developing rats. In addition, some of the behavioral changes described for prenatal-ethanol-exposed rats and mice (e.g., reduced responding for food and other rewards) as well as their response to various psychoactive drugs (e.g., amphetamines, methylphenidate, haloperidol) suggest that the DA system changes might extend into adulthood. Neurochemical studies on the effects of prenatal ethanol on DA systems of adults have not been reported for either species. The present study provides a neurochemical assessment of prenatal ethanol effects on DA systems of fully mature mice. Compared to chow and sucrose controls, adult offspring of mice fed a diet containing 25% ethanol derived calories had preadolescent growth deficits as observed in previous studies which also showed long-term behavioral deficits. Prenatal ethanol exposure in the present study, however, did not alter the concentration of DA or dihydroxyphenylacetic acid (DOPAC) nor the progressive decline in the concentration of these compounds in either striatum or nucleus accumbens of mature mice at intervals after synthesis inhibition by alpha-methyl-DL-p-tyrosine. Thus, the present study provides no neurochemical confirmation of altered DA systems resulting from prenatal ethanol exposure under conditions previously observed to alter adult behavior.

Patterns of growth deficiency in rats exposed in utero to undernutrition, ethanol, or the neuroteratogen methylazoxymethanol (MAM)

Children and experimental animals exposed to ethanol (EtOH) in utero commonly have low birthweights, and many remain small at maturity. Low body weight or small stature in adulthood may reflect an inability to recover from in utero growth retardation, or it may reflect a separate, postnatal growth deficiency. In this study, daily body weights (postnatal days 1 to 60) were compared among the offspring of the following groups of Long Evans rats: dams fed liquid diet containing 35% EtOH-derived calories; their pair-fed and chow-fed controls; and dams exposed to methylazoxymethanol (MAM) in two previous studies, in which offspring exhibited reduced numbers of growth hormone releasing factor (GRF) neurons. All treatments produced a number of offspring with weight deficits beginning after birth and persisting into maturity. Three distinct patterns of growth deficiency were observed: (1) weight loss relative to controls in the first weeks of life, seen in offspring exposed to EtOH, pair feeding, or MAM on gestation day 13 (G13); (2) a delay in the onset of the prepubertal growth spurt, seen in all EtOH-exposed offspring and in G13 MAM-exposed dwarfs; and (3) failure to sustain the prepubertal growth spurt, seen only after exposure to MAM on G14. The results of this study support the view that prenatal EtOH exposure is capable of affecting postnatal growth specifically; moreover, the pattern of growth deficiency seen in EtOH-exposed offspring was distinct from that of the undernourished offspring of pair-fed dams.

Prenatal ethanol effects on reward efficacy for adult mice are gestation stage specific

We previously reported that adult mice exposed to ethanol throughout gestation (G5-17) responded slower than controls on reinforcement schedules which required large numbers of responses per unit of food, i.e., high fixed ratio (FR) schedules. The primary finding of the present study was that ethanol exposure during the last 5 days of gestation (G12-17) is sufficient to produce this effect whereas a similar exposure early in gestation (G5-10) is not. Both male and female mice exposed to ethanol late in gestation responded slower than either lab chow or pair-fed controls, and the effect was similar to that of mice exposed to ethanol throughout gestation (G5-17) in our earlier study. Thus, developmental events occurring late in gestation are important for the reduced reinforcing efficacy of food for prenatal-ethanol-exposed mice. In addition, the present experiment established the comparability of the sucrose and lab chow controls on this task. The results of the present study and our previous report are compatible with the hypothesis that the reduced responding on high FR schedules exhibited by prenatal-ethanol-exposed mice reflects a reduction in the efficacy of food reward. It is possible that the reduction in reward efficacy is due to altered development of neuronal systems functionally related to reward which develop late in gestation.

Prenatal influence of alcohol following a single exposure in two inbred strains of mice

The effect of a single dose of ethanol on embryonic development was investigated in two inbred strains of mice. Ethanol (25% v/v solution, 0.02 ml/g body weight) was administered intraperitoneally on either gestational day 6, 9 or 12 to C57BL/6J and DBA/2J mice. All fetuses recovered near term were alive and appeared normal. The incidence of fetal death was not affected. Fetal weight was significantly reduced in the C57BL/6J strain of mice. Maternal exposure to a single and moderate dose of ethanol did not have any profound effect on the conceptus. For the development of laboratory models to mimic fetal alcohol effects in humans, the selection of appropriate genotype is important.

The effect of prenatal ethanol exposure on scentmarking in the C57BL/6J and C3H/He mouse strains

In utero exposure to ethanol has been shown to alter sexually dimorphic behaviors in rats. However, it is not clear whether this phenomenon is robust in other species, such as the mouse, which is sensitive to ethanol-induced birth defects. Further, it is not known whether significant differences exist across murine strains. If similar to the classic teratogenic effects of ethanol, it would be expected that strain differences in sensitivity should be evident, with some strains demonstrating an alteration in sexually dimorphic behavior and other strains demonstrating little or no effect. As a first attempt to address these issues, we have examined two mouse strains widely used in prenatal alcohol research, the inbred C3H/He and C57BL/6J strains. Scentmarking was selected as the behavior of interest. It is robustly sexually dimorphic in the rat and mouse, with males marking more than females and preliminary reports have demonstrated that in utero ethanol exposure reduces this behavior in the male rat. In the mouse strains selected for study, pregnant females were provided with either a liquid diet consisting of 25% ethanol-derived calories or pair-fed an isocaloric liquid diet from gestation days 6-18. An additional control group was included which was fed laboratory chow ad lib throughout gestation. Male and female offspring of each strain were tested for scentmarking at 65-75 days of age. As expected, results showed that the effect of prenatal ethanol exposure on scentmarking varied with both strain and sex. In the C3H/He strain, scentmarking was reduced significantly in male ethanol-exposed offspring (i.e., the males were feminized).(ABSTRACT TRUNCATED AT 250 WORDS)

Postnatal growth deficits in prenatal ethanol-exposed mice: characteristics and critical periods

We previously reported that offspring of C57BL/6 mice maintained on liquid diets containing 20% or 25% ethanol-derived calories throughout pregnancy had birth weights comparable with controls but had weight reductions that became manifest around 23 to 28 days postnatally. Since this pattern of weight reduction may represent an unrecognized condition for human ethanol exposure, we completed a number of experiments to more thoroughly characterize the altered growth of prenatal ethanol exposed C57BL/6 mice. The results of this study indicate that consumption of liquid diets containing either 17% or 25% ethanol-derived calories during pregnancy can reduce growth of male and female offspring. Although attenuated postnatal growth of prenatal ethanol-exposed rodents is not commonly reported, prospective studies in humans suggest that in addition to having lower birth weights, children prenatally exposed to ethanol are postnatally growth retarded. Mice exposed to the low ethanol doses used in the present study had normal birth weights; however, their growth was attenuated between 19 and 28 days of age (preadolescent growth spurt) resulting in a weight reduction for at least 35 days, and which according to our previous report could extend into adulthood. The latter stages of gestation appear to be more sensitive to the postnatal growth retarding effect of prenatal ethanol exposure than early gestation. Caloric deficiency and postnatal maternal factors were eliminated as possible mechanisms for the growth deficit.

Measures of maternal alcohol use as predictors of development in early childhood

The effect of prenatal alcohol exposure on growth, dysmorphology, and cognitive development at 6 years was examined in children whose mothers had completed a self-administered questionnaire during pregnancy. Drinking patterns prior to pregnancy recognition and indications of problem drinking (IPD) were assessed. Heavier alcohol intake was associated with slower growth in height and head circumference and increased dysmorphology, as evidenced by facial features associated with fetal alcohol syndrome (FAS) and the prevalence of probable/possible fetal alcohol effects (FAE). Indications of problem drinking predicted facial features associated with FAS and cognitive deficits (i.e., lower WPPSI Verbal IQ scores and lower scores on a test of receptive language function, the Token Test). Effects of alcohol consumption on head circumference and of indications of problem drinking on Verbal IQ and Token Test scores remained significant, even after excluding children born to mothers having drinkers (over seven drinks a day) and children with probable/possible FAE. Verbal IQ was an average of 7.1 points (95% confidence interval = 0.01, 14.25) lower among children born to mothers having more than one indication of problem drinking than it was among those born to women having fewer indications; Token Test scores were 4.3 points lower (95% confidence interval = 1.38, 7.24). Although the confidence intervals for these estimates are broad in this small, heterogeneous sample, their magnitude, if confirmed, is significant given that the population standard deviation for Verbal IQ is 15, and that for the Token Test is 5.

The effects of prenatal alcohol use on the growth of children at three years of age

In this prospective study of substance use during pregnancy, women were interviewed in their 4th and 7th prenatal months, and women and children were assessed at 24 hr, 8, 18, and 36 months postpartum. Data are presented on the outcome of 519 children at age 3. At 3 years, children who were exposed prenatally to alcohol were smaller in weight, length, and head circumference. They also had an increased number of minor physical anomalies. These effects were found even after controlling for nutritional and environmental factors. The persistence of growth effects at age 3 suggests that children exposed to alcohol prenatally may have a diminished capacity for growth.

Effects of prenatal ethanol exposure in C57BL mice on locomotor activity and passive avoidance behavior

The purpose of this study was to examine the long-term behavioral effects of prenatal ethanol exposure in C57BL mice. Pregnant mice received free access to a liquid diet containing 25% ethanol-derived calories (EDC) from gestation days 6 to 18. Control animals were pair-fed an isocaloric 0% EDC diet during the same period of time. An additional control group was included that was maintained on standard lab chow and water throughout pregnancy. At 30 days of age, female offspring were tested for spontaneous locomotor activity in an open field under two lighting conditions (dim or bright illumination). Male offspring were tested in a passive avoidance task at 25 days of age. The activity results demonstrated that the 25% EDC female progeny were more active than controls. This hyperactivity was observed under both lighting conditions, despite the fact that all groups evidenced suppressed activity when tested under bright lights. With regard to passive avoidance behavior, male EtOH-exposed offspring required a greater number of trials to reach criterion than controls. Additionally, they exhibited shorter latencies to enter the shock-associated chamber after receiving a single shock. Taken together, these results confirm our previous findings and demonstrate that C57BL mice are sensitive to both the deleterious behavioral and morphological consequences of prenatal ethanol exposure.

Effects of ethanol on mature offspring of mice given ethanol during pregnancy

Male offspring of mice maintained on isocaloric liquid diets containing either 20% ethanol or sucrose derived calories during pregnancy were tested on their ability to discriminate different ethanol doses as adults. They were trained to lever-press for a food reward on each of two levers in an operant chamber, and were then maintained on an FR20 reinforcement schedule. After response rates stabilized, ethanol discrimination training was initiated by reinforcing only responses made on the drug appropriate-lever after i.p. injections of ethanol (1.0 g/kg) or water. After learning to discriminate the 1.0 g dose, the animals' ability to discriminate doses of 0.25, 0.50, 0.75, 1.0, and 1.5 g/kg was assessed by determining the percentage of responses made on the drug lever during a 2-min test period. Compared to sucrose controls, mice exposed to alcohol in utero learned the lever response more slowly and were less responsive to injected ethanol as evidenced by a reduced effect of the drug on response rates and by a reduction in their ability to discriminate the presence of injected ethanol. The results indicate that prenatal ethanol exposure can have long term consequences which reduce the effects of ethanol in fully mature animals.