Computational models of ethanol-induced neurodevelopmental toxicity across species: Implications for risk assessment

Ginger (Zingiber Officinale Roscoe) ameliorates ethanol-induced cognitive impairment by modulating NMDA and GABA-A receptors in rat hippocampus

Brain damage caused by ethanol abuse may lead to permanent damage, including severe dementia. The aim of this study was to investigate the effects of ginger powder on ethanol-induced cognitive disorders by examining oxidative damage and inflammation status, and the gene expression of N-methyl-D-aspartate (NMDA) and γ-Aminobutyric acid (GABA)-A receptors in the hippocampus of male rats. 24 adult male Sprague-Dawley rats were allocated randomly to four groups as follows control, ethanol (4g/kg/day, by gavage), ginger (1g/kg/day, by gavage), and ginger-ethanol. At the end of the study, memory and learning were evaluated by the shuttle box test. Moreover, to explore mechanisms involved in ethanol-induced cognitive impairment and the protective effect of ginger, the expression of Nuclear factor kappa B (NF-κB), nuclear factor erythroid 2-related factor 2 (Nrf2), NMDA receptor, and GABA-A receptor was measured along with inflammatory and oxidative biomarkers in the hippocampus tissue. The results showed that ethanol could induce cognitive impairment in the ethanol group, while pretreatment with ginger could reverse it. The gene expression of the NF-κB/ Tumor necrosis factor (TNF)-α/Interleukin (IL)-1β pathway and NMDA and GABA-A receptors significantly increased in the ethanol group compared to the control group. While pretreatment with ginger could significantly improve ethanol-induced cognitive impairment through these pathways in the ginger-ethanol group compared to the ethanol group (P < 0.05). It can be concluded that ginger powder could ameliorate ethanol-induced cognitive impairment by modulating the expression of NMDA and GABA-A receptors and inhibiting oxidative damage and the NF-κB/TNF-α/IL-1β pathway in the rat hippocampus.

Developmental ethanol exposure has minimal impact on cerebellar microglial dynamics, morphology, and interactions with Purkinje cells during adolescence

Introduction

Fetal alcohol spectrum disorders (FASD) are the most common cause of non-heritable, preventable mental disability, occurring in almost 5% of births in the United States. FASD lead to physical, behavioral, and cognitive impairments, including deficits related to the cerebellum. There is no known cure for FASD and their mechanisms remain poorly understood. To better understand these mechanisms, we examined the cerebellum on a cellular level by studying microglia, the principal immune cells of the central nervous system, and Purkinje cells, the sole output of the cerebellum. Both cell types have been shown to be affected in models of FASD, with increased cell death, immune activation of microglia, and altered firing in Purkinje cells. While ethanol administered in adulthood can acutely depress the dynamics of the microglial process arbor, it is unknown how developmental ethanol exposure impacts microglia dynamics and their interactions with Purkinje cells in the long term.

Methods

To address this question, we used a mouse model of human 3rd trimester exposure, whereby L7cre/Ai9+/-/Cx3cr1G/+ mice (with fluorescently labeled microglia and Purkinje cells) of both sexes were subcutaneously treated with a binge-level dose of ethanol (5.0 g/kg/day) or saline from postnatal days 4-9. Cranial windows were implanted in adolescent mice above the cerebellum to examine the long-term effects of developmental ethanol exposure on cerebellar microglia and Purkinje cell interactions using in vivo two-photon imaging.

Results

We found that cerebellar microglia dynamics and morphology were not affected after developmental ethanol exposure. Microglia dynamics were also largely unaltered with respect to how they interact with Purkinje cells, although subtle changes in these interactions were observed in females in the molecular layer of the cerebellum.

Discussion

This work suggests that there are limited in vivo long-term effects of ethanol exposure on microglia morphology, dynamics, and neuronal interactions, so other avenues of research may be important in elucidating the mechanisms of FASD.

Dose-Related Reduction in Hippocampal Neuronal Populations in Fetal Alcohol Exposed Vervet Monkeys

Fetal alcohol spectrum disorder (FASD) is a chronic debilitating condition resulting in behavioral and intellectual impairments and is considered the most prevalent form of preventable mental retardation in the industrialized world. We previously reported that 2-year-old offspring of vervet monkey (Chlorocebus sabeus) dams drinking, on average, 2.3 ± 0.49 g ethanol per Kg maternal body weight 4 days per week during the last third of pregnancy had significantly lower numbers of CA1 (−51.6%), CA2 (−51.2%) and CA3 (−42.8%) hippocampal neurons, as compared to age-matched sucrose controls. Fetal alcohol-exposed (FAE) offspring also showed significantly lower volumes for these structures at 2 years of age. In the present study, we examined these same parameters in 12 FAE offspring with a similar average but a larger range of ethanol exposures (1.01–2.98 g/Kg/day; total ethanol exposure 24–158 g/Kg). Design-based stereology was performed on cresyl violet-stained and doublecortin (DCX)-immunostained sections of the hippocampus. We report here significant neuronal deficits in the hippocampus with a significant negative correlation between daily dose and neuronal population in CA1 (r² = 0.486), CA2 (r² = 0.492), and CA3 (r² = 0.469). There were also significant correlations between DCX population in the dentate gyrus and daily dose (r² = 0.560). Both correlations were consistent with linear dose-response models. This study illustrates that neuroanatomical sequelae of fetal ethanol exposure are dose-responsive and suggests that there may be a threshold for this effect.

Microglia and astrocytes show limited, acute alterations in morphology and protein expression following a single developmental alcohol exposure

Fetal alcohol spectrum disorders (FASD) are the most common cause of nonheritable, preventable mental disability and are characterized by cognitive, behavioral, and physical impairments. FASD occurs in almost 5% of births in the United States, but despite this prevalence there is no known cure, largely because the biological mechanisms that translate alcohol exposure to neuropathology are not well understood. While the effects of early ethanol exposure on neuronal survival and circuitry have received more attention, glia, the cells most closely tied to initiating and propagating inflammatory events, could be an important target for alcohol in the developing brain. Inflammation is known to alter developmental trajectories, but it has recently been shown that even small changes in both astrocytes and microglia in the absence of full-blown inflammatory signaling can alter brain function long-term. Here, we studied the acute response of astrocytes and microglia to a single exposure to ethanol in development across sexes in a mouse model of human third trimester exposure, in order to understand how these cells may transition from their normal developmental path to a different program that leads to FASD neuropathology. We found that although a single ethanol exposure delivered subcutaneously on postnatal day 4 did not cause large changes in microglial morphology or the expression of AldH1L1 and GFAP in the cortex and hippocampus, subtle effects were observed. These findings suggest that even a single, early ethanol exposure can induce mild acute alterations in glia that could contribute to developmental deficits.

Ethanol-mediated alterations in oligodendrocyte differentiation in the developing brain

INTRODUCTION

Alterations of white matter integrity and subsequent white matter structural deficits are consistent findings in Fetal Alcohol Syndrome (FAS), but knowledge regarding the molecular mechanisms underlying these abnormalities is incomplete. Experimental rodent models of FAS have shown dysregulation of cytokine expression leading to apoptosis of oligodendrocyte precursor cells (OPCs) and altered oligodendrocyte (OL) differentiation, but whether this is representative of human FAS pathogenesis has not been determined.

METHODS

Fetal brain tissue (12.2-21.4 weeks gestation) from subjects undergoing elective termination of pregnancy was collected according to an IRB-approved protocol. Ethanol (EtOH) exposure status was classified based on a detailed face-to-face questionnaire adapted from the National Institute on Alcohol Abuse and Alcoholism Prenatal Alcohol and Sudden Infant Death Syndrome and Stillbirth (PASS) study. Twenty EtOH-exposed fetuses were compared with 20 gestational age matched controls. Cytokine and OPC marker mRNA expression was quantified by Real-Time Polymerase chain reaction (qRT-PCR). Patterns of protein expression of OPC markers and active Capase-3 were studied by Fluorescence Activated Cell Sorting (FACS).

RESULTS

EtOH exposure was associated with reduced markers of cell viability, OPC differentiation, and OL maturation, while early OL differentiation markers were unchanged or increased. Expression of mRNAs for proteins specific to more mature forms of OL lineage (platelet-derived growth factor α (PDGFRα) and myelin basic protein (MBP) was lower in the EtOH group than in controls. Expression of the multifunctional growth and differentiation-promoting growth factor IGF-1, which is essential for normal development, also was reduced. Reductions were not observed for markers of early stages of OL differentiation, including Nuclear transcription factor NK-2 homeobox locus 2 (Nkx2.2). Expression of mRNAs for the proinflammatory cytokine, tumor necrosis factor-α (TNFα), and several proinflammatory chemokines was higher in the EtOH group compared to controls, including: Growth regulated protein alpha/chemokine (C-X-C motif) ligand 1 (GRO-α/CXCL1), Interleukin 8/chemokine (C-X-C motif) ligand 8 (IL8/CXCL8), Chemokine (C-X-C motif) ligand 6/Granulocyte chemotactic protein 2 (CXCL16/GCP2), epithelial-derived neutrophil-activating protein 78/chemokine (C-X-C motif) ligand 5 (ENA-78/CXCL5), monocyte chemoattractant protein-1 (MCP-1). EtOH exposure also was associated with an increase in the proportion of cells expressing markers of early stage OPCs, such as A2B5 and NG2. Finally, apoptosis (measured by caspase-3 activation) was increased substantially in the EtOH group compared to controls.

CONCLUSION

Prenatal EtOH exposure is associated with excessive OL apoptosis and/or delayed OL maturation in human fetal brain. This is accompanied by markedly dysregulated expression of several chemokines and cytokines, in a pattern predictive of increased OL cytotoxicity and reduced OL differentiation. These findings are consistent with findings in animal models of FAS.

Ethanol binge drinking during pregnancy and its effects on salivary glands of offspring rats: oxidative stress, morphometric changes and salivary function impairments

OBJECTIVES

To investigate the biochemical and morphological effects of ethanol (EtOH) binge drinking during pregnancy on parotid glands (PG), submandibular glands (SMG), and saliva of offspring rats.

METHODS

Pregnant Wistar rats (n = 8) were exposed to EtOH consumption (3 g/kg/day - 20 % w/v) for three consecutive days. The saliva of 40-day-old offspring rats was collected to determine amylase activity and total protein concentration. PG and SMG were collected to performe oxidative biochemistry, morphometric and immunohistochemistry analyses (Student's t-test, p < .05).

RESULTS

EtOH consumption during pregnancy significantly decreased the total protein concentration and decreased amylase activity. In the PG, the EtOH group showed increased lipid peroxidation and decreased antioxidant capacity against peroxyl. In the SMG, the EtOH group showed increased lipid peroxidation and NOx metabolite levels. PG exposed to EtOH showed a decrease of acini, ducts, and total parenchymal area. SMG exposed to EtOH showed an increase in the total stromal area. The expression of CK-19 and Vimentin were found not different between groups.

CONCLUSIONS

For the first time, a three-day EtOH binge-drinking protocol during pregnancy is associated with oxidative stress and morphometric alterations in the salivary glands of offspring rats and with the functional reduction of the main salivary enzyme (amylase).

CLINICAL RELEVANCE

EtOH consumption during pregnancy altered the morphology and physiology of the salivary glands of offspring rats.

Neurological and neuropsychological effects of low and moderate prenatal alcohol exposure

Several explanations for the diverse results in research on foetal alcohol spectrum disorders or alcohol-related neurodevelopmental disorder might be at hand: timing, amount and patterns of alcohol exposure, as well as complex epigenetic responses. The genetic background of the offspring and its interaction with other prenatal and post-natal environmental cues are likely also of importance. In the present report, key findings about the possible effects of low and moderate doses of maternal alcohol intake on the neuropsychological development of the offspring are reviewed and plausible mechanisms discussed. Special focus is put on the serotonergic system within developmental and gene-environment frameworks. The review also suggests guidelines for future studies and also summarizes some of to-be-answered questions of relevance to clinical practice. Contradictory findings and paucity of studies on the effects of exposure to low alcohol levels during foetal life for the offspring's neuropsychological development call for large prospective studies, as well as for studies including neuroimaging and multi-omics analyses to dissect the neurobiological underpinnings of alcohol exposure-related phenotypes and to identify biomarkers. Finally, it remains to be investigated whether any safe threshold of alcohol drinking during pregnancy can be identified.

Acute oligodendrocyte loss with persistent white matter injury in a third trimester equivalent mouse model of fetal alcohol spectrum disorder

Alcohol exposure during central nervous system (CNS) development can lead to fetal alcohol spectrum disorder (FASD). Human imaging studies have revealed significant white matter (WM) abnormalities linked to cognitive impairment in children with FASD; however, the underlying mechanisms remain unknown. Here, we evaluated both the acute and long-term impacts of alcohol exposure on oligodendrocyte number and WM integrity in a third trimester-equivalent mouse model of FASD, in which mouse pups were exposed to alcohol during the first 2 weeks of postnatal development. Our results demonstrate a 58% decrease in the number of mature oligodendrocytes (OLs) and a 75% decrease in the number of proliferating oligodendrocyte progenitor cells (OPCs) within the corpus callosum of alcohol-exposed mice at postnatal day 16 (P16). Interestingly, neither mature OLs nor OPCs derived from the postnatal subventricular zone (SVZ) were numerically affected by alcohol exposure, indicating heterogeneity in susceptibility based on OL ontogenetic origin. Although mature OL and proliferating OPC numbers recovered by postnatal day 50 (P50), abnormalities in myelin protein expression and microstructure within the corpus callosum of alcohol-exposed subjects persisted, as assessed by western immunoblotting of myelin basic protein (MBP; decreased expression) and MRI diffusion tensor imaging (DTI; decreased fractional anisotropy). These results indicate that third trimester-equivalent alcohol exposure leads to an acute, albeit recoverable, decrease in OL lineage cell numbers, accompanied by enduring WM injury. Additionally, our finding of heterogeneity in alcohol susceptibility based on the developmental origin of OLs may have therapeutic implications in FASD and other disorders of WM development.

Applying evolutionary genetics to developmental toxicology and risk assessment

Evolutionary thinking continues to challenge our views on health and disease. Yet, there is a communication gap between evolutionary biologists and toxicologists in recognizing the connections among developmental pathways, high-throughput screening, and birth defects in humans. To increase our capability in identifying potential developmental toxicants in humans, we propose to apply evolutionary genetics to improve the experimental design and data interpretation with various in vitro and whole-organism models. We review five molecular systems of stress response and update 18 consensual cell-cell signaling pathways that are the hallmark for early development, organogenesis, and differentiation; and revisit the principles of teratology in light of recent advances in high-throughput screening, big data techniques, and systems toxicology. Multiscale systems modeling plays an integral role in the evolutionary approach to cross-species extrapolation. Phylogenetic analysis and comparative bioinformatics are both valuable tools in identifying and validating the molecular initiating events that account for adverse developmental outcomes in humans. The discordance of susceptibility between test species and humans (ontogeny) reflects their differences in evolutionary history (phylogeny). This synthesis not only can lead to novel applications in developmental toxicity and risk assessment, but also can pave the way for applying an evo-devo perspective to the study of developmental origins of health and disease.

Consequences of low or moderate prenatal ethanol exposures during gastrulation or neurulation for open field activity and emotionality in mice

In a previous study we used a mouse model for ethanol exposure during gastrulation or neurulation to investigate the effects of modest and occasional human drinking during the 3rd or 4th week of pregnancy (Schambra et al., 2015). Pregnant C57Bl/6J mice were treated by gavage during gastrulation on gestational day (GD) 7 or neurulation on GD8 with 2 doses 4h apart of either 2.4 or 2.9g ethanol/kg body weight, resulting in peak blood ethanol concentrations (BECs) of 104 and 177mg/dl, respectively. We found that mice exposed to the low dose on either day were significantly delayed in their neonatal sensorimotor development. In the present study, we tested the same cohort of mice in an open field as juveniles on postnatal day (PD) 23-25 and as young adults on PD65-67 for prenatal ethanol effects on exploration and emotionality with measures of activity, rearing, grooming and defecation. We evaluated the effects of dose, sex, day of treatment and day of birth by multiple regression analyses. We found that, compared to the respective gavage controls, juvenile mice that had been prenatally exposed to the low BEC on either GD7 or GD8 were significantly hypoactive on the first 2 test days, reared significantly more on the last 2 test days, and groomed and defecated significantly more on all 3 test days. Only mice that had been treated on GD7 remained hypoactive as adults. Juvenile mice prenatally exposed to the moderate BEC on GD7 groomed significantly more, while those exposed on GD8 reared and defecated significantly more. Sex differences were highly significant in adult control mice, with control males less active and more emotional than females. Similar, but smaller, sex differences were also evident in adults exposed to ethanol prenatally. Persistence into later life of a deleterious effect of premature birth (i.e., birth on GD19 rather than GD20) on weight and behavior was not consistently supported by these data. Importantly, mice shown previously to be delayed in sensorimotor development as neonates, in the present study demonstrated hypoactivity and increased emotionality in open field behaviors as juveniles, and those mice exposed during gastrulation remained hypoactive as adults. Thus, we propose that the delayed motor development, hypoactivity and emotionality we observed in mice exposed to a low BEC during gastrulation or neurulation may relate to an attention deficit-activity disorder in humans, possibly the inattentive subtype, or Sluggish Cognitive Tempo (SCT). We further discuss concerns about occasional light or moderate alcohol consumption during the 3rd or 4th week of human pregnancy.

Developmental stress and lead (Pb): Effects of maternal separation and/or Pb on corticosterone, monoamines, and blood Pb in rats

The level of lead (Pb) exposure in children has decreased dramatically since restrictions on its use were implemented. However, even with restrictions, children are exposed to Pb and still present with cognitive and behavioral deficits. One prominent aspect of the exposome of these children is that many come from low social economic status (SES) conditions, and low SES is associated with stress. In order to compare the combined effects of early stress and Pb, Sprague-Dawley rats were exposed to vehicle or Pb either alone or in combination with maternal separation stress during brain development (i.e., postnatal day (P)4-P11, P19, or P28). Maternally separated/isolated pups had lower body and thymus weights during exposure and had increased levels of blood Pb compared with vehicle controls. Isolation, but not Pb, affected the response to an acute stressor (standing in shallow water) when assessed on P19 and P29, but not earlier on P11. Interactions of Pb and isolation were found on monoamines in the neostriatum, hippocampus, and hypothalamus on turnover but not on levels, and most changes were on dopamine turnover. Isolation had greater short-term effects than Pb. Interactions were dependent on age, sex, and acute stress.

Hepato- and neuro-protective effects of watermelon juice on acute ethanol-induced oxidative stress in rats

Chronic and acute alcohol exposure has been extensively reported to cause oxidative stress in hepatic and extra-hepatic tissues. Watermelon (Citrullus lanatus) is known to possess various beneficial properties including; antioxidant, anti-inflammatory, analgesic, anti-diabetic, anti-ulcerogenic effects. However, there is a lack of pertinent information on its importance in acute alcohol-induced hepato- and neuro-toxicity. The present study evaluated the potential protective effects of watermelon juice on ethanol-induced oxidative stress in the liver and brain of male Wistar rats. Rats were pre-treated with the watermelon juice at a dose of 4 ml/kg body weight for a period of fifteen days prior to a single dose of ethanol (50%; 12 ml/kg body weight). Ethanol treatment reduced body weight gain and significantly altered antioxidant status in the liver and brain. This is evidenced by the significant elevation of malondialdehyde (MDA) concentration; depletion in reduced glutathione (GSH) levels and an increased catalase (CAT) activity in the brain and liver. There was no significant difference in the activity of glutathione peroxidase (GPX) in the liver and brain.

Oral administration of watermelon juice for fifteen (15) days prior to ethanol intoxication, significantly reduced the concentration of MDA in the liver and brain of rats. In addition, water melon pre-treatment increased the concentration of GSH and normalized catalase activity in both tissues in comparison to the ethanol control group. Phytochemical analysis revealed the presence of phenol, alkaloids, saponins, tannins and steroids in watermelon juice. Our findings indicate that watermelon juice demonstrate anti-oxidative effects in ethanol-induced oxidation in the liver and brain of rats; which could be associated with the plethora of antioxidant phyto-constituents present there-in.

High postnatal susceptibility of hippocampal cytoskeleton in response to ethanol exposure during pregnancy and lactation

Ethanol exposure to offspring during pregnancy and lactation leads to developmental disorders, including central nervous system dysfunction. In the present work, we have studied the effect of chronic ethanol exposure during pregnancy and lactation on the phosphorylating system associated with the astrocytic and neuronal intermediate filament (IF) proteins: glial fibrillary acidic protein (GFAP), and neurofilament (NF) subunits of low, medium, and high molecular weight (NFL, NFM, and NFH, respectively) in 9- and 21-day-old pups. Female rats were fed with 20% ethanol in their drinking water during pregnancy and lactation. The homeostasis of the IF phosphorylation was not altered in the cerebral cortex, cerebellum, or hippocampus of 9-day-old pups. However, GFAP, NFL, and NFM were hyperphosphorylated in the hippocampus of 21-day-old pups. PKA had been activated in the hippocampus, and Ser55 in the N-terminal region of NFL was hyperphosphorylated. In addition, JNK/MAPK was activated and KSP repeats in the C-terminal region of NFM were hyperphosphorylated in the hippocampus of 21-day-old pups. Decreased NFH immunocontent but an unaltered total NFH/phosphoNFH ratio suggested altered stoichiometry of NFs in the hippocampus of ethanol-exposed 21-day-old pups. In contrast to the high susceptibility of hippocampal cytoskeleton in developing rats, the homeostasis of the cytoskeleton of ethanol-fed adult females was not altered. Disruption of the cytoskeletal homeostasis in neural cells supports the view that regions of the brain are differentially vulnerable to alcohol insult during pregnancy and lactation, suggesting that modulation of JNK/MAPK and PKA signaling cascades target the hippocampal cytoskeleton in a window of vulnerability in 21-day-old pups. Our findings are relevant, since disruption of the cytoskeleton in immature hippocampus could contribute to later hippocampal damage associated with ethanol toxicity.

Exposure of neonatal rats to alcohol has differential effects on neuroinflammation and neuronal survival in the cerebellum and hippocampus

Background

Fetal alcohol exposure is a leading cause of preventable birth defects, yet drinking during pregnancy remains prevalent worldwide. Studies suggest that activation of the neuroimmune system plays a role in the effects of alcohol exposure during the rodent equivalent to the third trimester of human pregnancy (i.e., first week of neonatal life), particularly by contributing to neuronal loss. Here, we performed a comprehensive study investigating differences in the neuroimmune response in the cerebellum and hippocampus, which are important targets of third trimester-equivalent alcohol exposure.

Methods

To model heavy, binge-like alcohol exposure during this period, we exposed rats to alcohol vapor inhalation during postnatal days (P)3–5 (blood alcohol concentration = 0.5 g/dL). The cerebellar vermis and hippocampus of rat pups were analyzed for signs of glial cell activation and neuronal loss by immunohistochemistry at different developmental stages. Cytokine production was measured by reverse transcriptase polymerase chain reaction during peak blood alcohol concentration and withdrawal periods. Additionally, adolescent offspring were assessed for alterations in gait and spatial memory.

Results

We found that this paradigm causes Purkinje cell degeneration in the cerebellar vermis at P6 and P45; however, no signs of neuronal loss were found in the hippocampus. Significant increases in pro-inflammatory cytokines were observed in both brain regions during alcohol withdrawal periods. Although astrocyte activation occurred in both the hippocampus and cerebellar vermis, microglial activation was observed primarily in the latter.

Conclusions

These findings suggest that heavy, binge-like third trimester-equivalent alcohol exposure has time- and brain region-dependent effects on cytokine levels, morphological activation of microglia and astrocytes, and neuronal survival.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-015-0382-9) contains supplementary material, which is available to authorized users.

Third trimester-equivalent ethanol exposure increases anxiety-like behavior and glutamatergic transmission in the basolateral amygdala

Ethanol consumption during pregnancy produces a wide range of morphological and behavioral alterations known as fetal alcohol spectrum disorder (FASD). Among the behavioral deficits associated with FASD is an increased probability of developing anxiety disorders. Studies with animal models of FASD have demonstrated that ethanol exposure during the equivalent to the 1(st) and 2(nd) trimesters of human pregnancy increases anxiety-like behavior. Here, we examined the impact on this type of behavior of exposure to high doses of ethanol in vapor inhalation chambers during the rat equivalent to the human 3rd trimester of pregnancy (i.e., neonatal period in these animals). We evaluated anxiety-like behavior with the elevated plus maze. Using whole-cell patch-clamp electrophysiological techniques in brain slices, we also characterized glutamatergic and GABAergic synaptic transmission in the basolateral amygdala, a brain region that has been implicated to play a role in emotional behavior. We found that ethanol-exposed adolescent offspring preferred the closed arms over the open arms in the elevated plus maze and displayed lower head dipping activity than controls. Electrophysiological measurements showed an increase in the frequency of spontaneous and miniature excitatory postsynaptic currents in pyramidal neurons from the ethanol group. These findings suggest that high-dose ethanol exposure during the equivalent to the last trimester of human pregnancy can persistently increase excitatory synaptic inputs to principal neurons in the basolateral amygdala, leading to an increase in anxiety-like behaviors.

Low and moderate prenatal ethanol exposures of mice during gastrulation or neurulation delays neurobehavioral development

Human and animal studies show significant delays in neurobehavioral development in offspring after prolonged prenatal exposure to moderate and high ethanol doses resulting in high blood alcohol concentration (BECs). However, none have investigated the effects of lower ethanol doses given acutely during specific developmental time periods. Here, we sought to create a mouse model for modest and circumscribed human drinking during the 3rd and 4th weeks of pregnancy. We acutely treated mice during embryo gastrulation on gestational day (GD) 7 or neurulation on GD8 with a low or moderate ethanol dose given via gavage that resulted in BECs of 107 and 177 mg/dl, respectively. We assessed neonatal physical development (pinnae unfolding, and eye opening); weight gain from postnatal day (PD) 3-65; and neurobehavioral maturation (pivoting, walking, cliff aversion, surface righting, vertical screen grasp, and rope balance) from PD3 to 17. We used a multiple linear regression model to determine the effects of dose, sex, day of treatment and birth in animals dosed during gastrulation or neurulation, relative to their vehicle controls. We found that ethanol exposure during both time points (GD7 and GD8) resulted in some delays of physical development and significant sensorimotor delays of pivoting, walking, and thick rope balance, as well as additional significant delays in cliff aversion and surface righting after GD8 treatment. We also found that treatment with the low ethanol dose more frequently affected neurobehavioral development of the surviving pups than treatment with the moderate ethanol dose, possibly due to a loss of severely affected offspring. Finally, mice born prematurely were delayed in their physical and sensorimotor development. Importantly, we showed that brief exposure to low dose ethanol, if administered during vulnerable periods of neuroanatomical development, results in significant neurobehavioral delays in neonatal mice. We thus expand concerns about alcohol consumption during the 3rd and 4th weeks of human pregnancy to include occasional light to moderate drinking.

Effect of repeated alcohol exposure during the third trimester-equivalent on messenger RNA levels for interleukin-1β, chemokine (C-C motif) ligand 2, and interleukin 10 in the developing rat brain after injection of lipopolysaccharide

Microglia undergo maturation during the third trimester of human development (equivalent to the first 1-2 weeks of postnatal life in rodents), during which these cells may be particularly sensitive to insult. Alcohol exposure during this period can activate the neuroimmune system, an effect that may contribute to the pathophysiology of fetal alcohol spectrum disorders. Here, we investigated whether repeated alcohol exposure during the third trimester-equivalent in rats has a priming effect on the neuroimmune response to injection of bacterial lipopolysaccharide (LPS). Pups were exposed to alcohol in vapor chambers for 4 h daily from postnatal day (PD)2 to PD16 (peak blood alcohol concentrations ∼150 mg/dL). On PD17, rats were injected with either saline or LPS (50 μg/kg) and the frontal cortex, cerebellar vermis, and dentate gyrus were collected 2 h later. Messenger RNA (mRNA) levels for the pro-inflammatory agents interleukin 1β (IL-1β) and chemokine (C-C) motif ligand 2 (CCL2), as well as levels of the anti-inflammatory cytokine interleukin 10 (IL-10), were measured using reverse transcriptase polymerase chain reaction. LPS consistently increased IL-1β and CCL2 mRNA levels in the dentate gyrus, frontal cortex, and cerebellum of both male and female rats. Furthermore, the LPS-induced increase of IL-1β mRNA levels was significantly blunted in the frontal cortex of alcohol-exposed female rats. Conversely, LPS only minimally affected IL-10 mRNA expression and there were no significant differences between air- and alcohol-exposed rats. Taken together with the literature regarding the effect of third-trimester alcohol exposure on the neuroimmune system, our findings suggest that chronic exposure to lower levels is less disruptive to the neuroimmune system than binge-like exposure to high doses of alcohol.

Repeated intermittent alcohol exposure during the third trimester-equivalent increases expression of the GABA(A) receptor δ subunit in cerebellar granule neurons and delays motor development in rats

Exposure to ethanol (EtOH) during fetal development can lead to long-lasting alterations, including deficits in fine motor skills and motor learning. Studies suggest that these are, in part, a consequence of cerebellar damage. Cerebellar granule neurons (CGNs) are the gateway of information into the cerebellar cortex. Functionally, CGNs are heavily regulated by phasic and tonic GABAergic inhibition from Golgi cell interneurons; however, the effect of EtOH exposure on the development of GABAergic transmission in immature CGNs has not been investigated. To model EtOH exposure during the 3rd trimester-equivalent of human pregnancy, neonatal pups were exposed intermittently to high levels of vaporized EtOH from postnatal day (P) 2 to P12. This exposure gradually increased pup serum EtOH concentrations (SECs) to ∼60 mM (∼0.28 g/dl) during the 4 h of exposure. EtOH levels gradually decreased to baseline 8 h after the end of exposure. Surprisingly, basal tonic and phasic GABAergic currents in CGNs were not significantly affected by postnatal alcohol exposure (PAE). However, PAE increased δ subunit expression at P28 as detected by immunohistochemical and western blot analyses. Also, electrophysiological studies with an agonist that is highly selective for δ-containing GABA(A) receptors, 4,5,6,7-tetrahydroisoxazolo[4,5-c]pyridine-3-ol (THIP), showed an increase in THIP-induced tonic current. Behavioral studies of PAE rats did not reveal any deficits in motor coordination, except for a delay in the acquisition of the mid-air righting reflex that was apparent at P15 to P18. These findings demonstrate that repeated intermittent exposure to high levels of EtOH during the equivalent of the last trimester of human pregnancy has significant but relatively subtle effects on motor coordination and GABAergic transmission in CGNs in rats.

Does moderate drinking harm the fetal brain? Insights from animal models

Although public health campaigns advise pregnant women to abstain from ethanol, drinking during pregnancy is pervasive. Here, we highlight recent studies that have clearly demonstrated long-lasting neurobehavioral deficits in the offspring of laboratory animals exposed to moderate levels of ethanol during development. Alterations in learning, memory, motor coordination, social behavior, and stress responses were identified in these animals. Increased vulnerability to substance abuse was also demonstrated. These behavioral alterations have been associated with impairments in neurotransmitter systems, neuromodulators, and/or synaptic plasticity in several brain regions. With this review we hope to contribute to a better appreciation of the potential effects of developmental exposure to moderate ethanol levels, leading to better interventions aimed at relieving fetal alcohol spectrum disorders.

Cellular and mitochondrial effects of alcohol consumption

Alcohol dependence is correlated with a wide spectrum of medical, psychological, behavioral, and social problems. Acute alcohol abuse causes damage to and functional impairment of several organs affecting protein, carbohydrate, and fat metabolism. Mitochondria participate with the conversion of acetaldehyde into acetate and the generation of increased amounts of NADH. Prenatal exposure to ethanol during fetal development induces a wide spectrum of adverse effects in offspring, such as neurologic abnormalities and pre- and post-natal growth retardation. Antioxidant effects have been described due to that alcoholic beverages contain different compounds, such as polyphenols as well as resveratrol. This review analyzes diverse topics on the alcohol consumption effects in several human organs and demonstrates the direct participation of mitochondria as potential target of compounds that can be used to prevent therapies for alcohol abusers.

In vitro and in vivo models of acute alcohol exposure

Alcohol abuse is a global problem due to the financial burden on society and the healthcare system. While the harmful health effects of chronic alcohol abuse are well established, more recent data suggest that acute alcohol consumption also affects human wellbeing. Thus, there is a need for research models in order to fully understand the effect of acute alcohol abuse on different body systems and organs. The present manuscript summarizes the interdisciplinary advantages and disadvantages of currently available human and non-human models of acute alcohol abuse, and identifies their suitability for biomedical research.

A lifestage-specific approach to hazard and dose-response characterization for children's health risk assessment

In 2006, the U.S. EPA published a report entitled A Framework for Assessing Health Risks of Environmental Exposures to Children (hereafter referred to as the "Framework") describing a lifestage approach to risk assessment that includes the evaluation of existing data from a temporal perspective (i.e., the timing of both the exposure and the outcome). This article summarizes the lifestage-specific issues discussed in the Framework related to the qualitative and the quantitative hazard and dose-response characterization. Lifestage-specific hazard characterization includes an evaluation of relevant human and experimental animal studies, focusing on the identification of critical windows of development (i.e., exposure intervals of maximum susceptibility) for observed outcomes, evaluation of differential exposure at individual lifestages, the relevance and impact of lifestage-specific toxicokinetic and toxicodynamic data, mode of action information, variability and latency of effects from early lifestage exposure, and describing uncertainties. The interpretation of the hazard data to determine the strength of association between early life exposures and the timing and type of outcomes depends upon the overall weight of evidence. Lifestage-specific dose-response characterization relies on the identification of susceptible lifestages in order to quantify health risk, information on the point of departure, key default assumptions, and descriptions of uncertainty, sensitivity, and variability. Discussion of the strength and limitations of the hazard and dose-response data provides a basis for confidence in risk determinations. Applying a lifestage approach to hazard and dose-response characterization is likely to improve children's health risk assessment by identifying data gaps and providing a better understanding of sources of uncertainty.