Molecular pathways underpinning ethanol-induced neurodegeneration

The ameliorative effects of choline on ethanol-induced cell death in the neural tube of susceptible BXD strains of mice

Introduction

Fetal alcohol spectrum disorders (FASD) are the leading preventable cause of intellectual disability, providing the impetus for evaluating various potential treatments to ameliorate ethanol's teratogenic effects, particularly in the nervous system. One treatment is the dietary supplement choline which has been shown to mitigate at least some of ethanol's teratogenic effects. The present study was designed to investigate the effects of genetics on choline's efficacy in ameliorating cell death in the developing neural tube. Previously, we examined BXD recombinant inbred mice, and their parental C57BL/6 J (B6) and DBA/2 J strains, and identified strains that were sensitive to ethanol's teratogenic actions. Thus, we used these strains to identify response to choline treatment.

Materials and methods

Timed pregnant mice from 4 strains (B6, BXD51, BXD73, BXD2) were given either ethanol or isocaloric maltose-dextrin (5.8 g/kg in two administrations separated by 2 h) with choline at one of 3 doses: 0, 100 or 250 mg/kg. Subjects were exposed via intragastric gavage on embryonic day 9 and embryos were collected 7 h after the initial ethanol administrations. Cell death was analyzed using TUNEL staining in the developing forebrain and brainstem.

Results

Choline ameliorated the ethanol-induced cell death across all 4 strains without causing enhanced cell death in control mice. Choline was effective in both the developing telencephalon and in the brainstem. Both doses diminished cell death, with some differences across strains and brain regions, although the 100 mg/kg dose was most consistent in mitigating ethanol-related cell death. Comparisons across strains showed that there was an effect of strain, particularly in the forebrain at the higher dose.

Discussion

These results show that choline is effective in ameliorating ethanol-induced cell death at this early stage of nervous system development. However, there were some strain differences in its efficacy, especially at the high dose, providing further evidence of the importance of genetics in influencing the ability of choline to protect against prenatal alcohol exposure.

Effects of genetics and sex on adolescent behaviors following neonatal ethanol exposure in BXD recombinant inbred strains

Introduction

Fetal alcohol spectrum disorders (FASD) are the leading preventable neurodevelopmental disorders and two hallmark symptoms of FASD are abnormal behavior, and cognitive and learning deficits. The severity of alcohol's teratogenic effects on the developing brain is influenced by genetics and sex. We previously identified recombinant inbred BXD mouse strains that show differential vulnerability to ethanol-induced cell death in the developing hippocampus, a brain region important in learning and memory. The present study aimed to test the hypothesis that strains with increased vulnerability to ethanol-induced cell death in the hippocampus have concomitant deficits in multiple hippocampal-related behaviors during adolescence.

Methods

The current study evaluated the effects of developmental ethanol exposure on adolescent behavior in two BXD strains that show high cell death (BXD48a, BXD100), two that show low cell death (BXD60, BXD71), and the two parental strains (C57BL/6 J (B6), DBA/2 J (D2)). On postnatal day 7, male and female neonatal pups were treated with ethanol (5.0 g/kg) or saline given in two equal doses 2 h apart. Adolescent behavior was assessed across multiple behavioral paradigms including the elevated plus maze, open field, Y-maze, and T-maze.

Results

Our results demonstrate that the effects of developmental ethanol exposure on adolescent behavioral responses are highly dependent on strain. The low cell death strains, BXD60 and BXD71, showed minimal effect of ethanol exposure on all behavioral measures but did present sex differences. The parental -B6 and D2-strains and high cell death strains, BXD48a and BXD100, showed ethanol-induced effects on activity-related or anxiety-like behaviors. Interestingly, the high cell death strains were the only strains that showed a significant effect of postnatal ethanol exposure on hippocampal-dependent spatial learning and memory behaviors.

Discussion

Overall, we identified effects of ethanol exposure, strain, and/or sex on multiple behavioral measures. Interestingly, the strains that showed the most effects of postnatal ethanol exposure on adolescent behavior were the BXD strains that show high ethanol-induced cell death in the neonatal hippocampus, consistent with our hypothesis. Additionally, we found evidence for interactions among strain and sex, demonstrating that these factors have a complex effect on alcohol responses and that both are important considerations.

Effects of Genetics and Sex on Acute Gene Expression Changes in the Hippocampus Following Neonatal Ethanol Exposure in BXD Recombinant Inbred Mouse Strains

Fetal alcohol spectrum disorders (FASD) are prevalent neurodevelopmental disorders. Genetics have been shown to have a role in the severity of alcohol's teratogenic effects on the developing brain. We previously identified recombinant inbred BXD mouse strains that show high (HCD) or low cell death (LCD) in the hippocampus following ethanol exposure. The present study aimed to identify gene networks that influence this susceptibility. On postnatal day 7 (3rd-trimester-equivalent), male and female neonates were treated with ethanol (5.0 g/kg) or saline, and hippocampi were collected 7hrs later. Using the Affymetrix microarray platform, ethanol-induced gene expression changes were identified in all strains with divergent expression sets found between sexes. Genes, such as Bcl2l11, Jun, and Tgfb3, showed significant strain-by-treatment interactions and were involved in many apoptosis pathways. Comparison of HCD versus LCD showed twice as many ethanol-induced genes changes in the HCD. Interestingly, these changes were regulated in the same direction suggesting (1) more perturbed effects in HCD compared to LCD and (2) limited gene expression changes that confer resistance to ethanol-induced cell death in LCD. These results demonstrate that genetic background and sex are important factors that affect differential cell death pathways after alcohol exposure during development that could have long-term consequences.

Astrocyte ethanol exposure reveals persistent and defined calcium response subtypes and associated gene signatures

Astrocytes play a critical role in brain function, but their contribution during ethanol (EtOH) consumption remains largely understudied. In light of recent findings on the heterogeneity of astrocyte physiology and gene expression, an approach with the ability to identify subtypes and capture this heterogeneity is necessary. Here, we combined measurements of calcium signaling and gene expression to define EtOH-induced astrocyte subtypes. In the absence of a demonstrated EtOH receptor, EtOH is believed to have effects on the function of many receptors and downstream biological cascades that underlie calcium responsiveness. This mechanism of EtOH-induced calcium signaling is unknown and this study provides the first step in understanding the characteristics of cells displaying these observed responses. To characterize underlying astrocyte subtypes, we assessed the correlation between calcium signaling and astrocyte gene expression signature in response to EtOH. We found that various EtOH doses increased intracellular calcium levels in a subset of astrocytes, distinguishing three cellular response types and one nonresponsive subtype as categorized by response waveform properties. Furthermore, single-cell RNA-seq analysis of astrocytes from the different response types identified type-enriched discriminatory gene expression signatures. Combining single-cell calcium responses and gene expression analysis identified specific astrocyte subgroups among astrocyte populations defined by their response to EtOH. This result provides a basis for identifying the relationship between astrocyte susceptibility to EtOH and corresponding measurable markers of calcium signaling and gene expression, which will be useful to investigate potential subgroup-specific influences of astrocytes on the physiology and pathology of EtOH exposure in the brain.

Intracellular signaling molecules of nerve tissue progenitors as pharmacological targets for treatment of ethanol-induced neurodegeneration

OBJECTIVES

The development of approaches to the treatment of neurodegenerative diseases caused by alcohol abuse by targeted pharmacological regulation of intracellular signaling transduction of progenitor cells of nerve tissue is promising. We studied peculiarities of participation of NF-кB-, сАМР/РКА-, JAKs/STAT3-, ERK1/2-, p38-pathways in the regulation of neural stem cells (NSC) and neuronal-committed progenitors (NCP) in the simulation of ethanol-induced neurodegeneration in vitro and in vivo.

METHODS

In vitro, the role of signaling molecules (NF-кB, сАМР, РКА, JAKs, STAT3, ERK1/2, p38) in realizing the growth potential of neural stem cells (NSC) and neuronal-committed progenitors (NCP) in ethanol-induced neurodegeneration modeled in vitro and in vivo was studied. To do this, the method of the pharmacological blockade with the use of selective inhibitors of individual signaling molecules was used.

RESULTS

Several of fundamental differences in the role of certain intracellular signaling molecules (SM) in proliferation and specialization of NSC and NCP have been revealed. It has been shown that the effect of ethanol on progenitors is accompanied by the formation of a qualitatively new pattern of signaling pathways. Data have been obtained on the possibility of stimulation of nerve tissue regeneration in ethanol-induced neurodegeneration by NF-кB and STAT3 inhibitors. It has been found that the blockage of these SM stimulates NSC and NCP in conditions of ethanol intoxication and does not have a «negative» effect on the realization of the growth potential of intact progenitors (which will appear de novo during therapy).

CONCLUSIONS

The results may serve as a basis for the development of fundamentally new drugs to the treatment of alcoholic encephalopathy and other diseases of the central nervous system associated with alcohol abuse.

Primary cilia safeguard cortical neurons in neonatal mouse forebrain from environmental stress-induced dendritic degeneration

The developing brain is under the risk of exposure to a multitude of environmental stressors. While perinatal exposure to excessive levels of environmental stress is responsible for a wide spectrum of neurological and psychiatric conditions, the developing brain is equipped with intrinsic cell protection, the mechanisms of which remain unknown. Here we show, using neonatal mouse as a model system, that primary cilia, hair-like protrusions from the neuronal cell body, play an essential role in protecting immature neurons from the negative impacts of exposure to environmental stress. More specifically, we found that primary cilia prevent the degeneration of dendritic arbors upon exposure to alcohol and ketamine, two major cell stressors, by activating cilia-localized insulin-like growth factor 1 receptor and downstream Akt signaling. We also found that activation of this pathway inhibits Caspase-3 activation and caspase-mediated cleavage/fragmentation of cytoskeletal proteins in stress-exposed neurons. These results indicate that primary cilia play an integral role in mitigating adverse impacts of environmental stressors such as drugs on perinatal brain development.

Docosahexaenoic Acid: Outlining the Therapeutic Nutrient Potential to Combat the Prenatal Alcohol-Induced Insults on Brain Development

Brain development is markedly affected by prenatal alcohol exposure, leading to cognitive and behavioral problems in the children. Protecting neuronal damage from prenatal alcohol could improve neural connections and functioning of the brain. DHA, a n-3 (ω-3) long-chain PUFA, is involved in the development of neurons. Insufficient concentrations of DHA impair neuronal development and plasticity of synaptic junctions and affect neurotransmitter concentrations in the brain. Alcohol consumption during pregnancy decreases the maternal DHA status and reduces the placental transfer of DHA to the fetus, resulting in less DHA being available for brain development. It is important to know whether DHA could induce beneficial effects on various physiological functions that promote neuronal development. This review will discuss the current evidence for the beneficial role of DHA in protecting against neuronal damage and its potential in mitigating the teratogenic effects of alcohol.

Neonatal Alcohol Exposure in Mice Induces Select Differentiation- and Apoptosis-Related Chromatin Changes Both Independent of and Dependent on Sex

Prenatal alcohol exposure (PAE) affects many aspects of physiology and behavior, including brain development. Specifically, ethanol can influence expression of genes important for brain growth, including chromatin modifiers. Ethanol can also increase apoptotic cell death in the brain and alter epigenetic profiles such as modifications to histones and DNA methylation. Although differential sex outcomes and disruptions to the function of multiple brain regions have been reported in fetal alcohol spectrum disorder (FASD), the majority of our knowledge on molecular epigenetic and apoptotic dysregulation in PAE is based on data from males and is sometimes limited to assessments of the whole brain or one brain region. Here, we examined histone modifications, DNA methylation, and expression of genes involved in differentiation and proliferation related-chromatin modifications and apoptosis in the cerebral cortex and cerebellum of C57BL/6J mice exposed to an acute alcohol challenge on postnatal day 7, with a focus on differential outcomes between sexes and brain regions. We found that neonatal alcohol exposure altered histone modifications, and impacted expression of a select few chromatin modifier and apoptotic genes in both the cortex and cerebellum. The results were observed primarily in a sex-independent manner, although some additional trends toward sexual dimorphisms were observed. Alcohol exposure induced trends toward increased bulk H3K4me3 levels, increased Kmt2e expression, and elevated levels of Casp6 mRNA and bulk γH2A.X. Additional trends indicated that ethanol may impact Kdm4a promoter DNA methylation levels and bulk levels of the histone variant H2A.Z, although further studies are needed. We comprehensively examined effects of ethanol exposure across different sexes and brain regions, and our results suggest that major impacts of ethanol on bulk chromatin modifications underlying differentiation and apoptosis may be broadly applicable across the rodent cortex and cerebellum in both sexes.

Natural Dietary Supplementation of Curcumin Protects Mice Brains against Ethanol-Induced Oxidative Stress-Mediated Neurodegeneration and Memory Impairment via Nrf2/TLR4/RAGE Signaling

The aim of the current study was to explore the underlying neuroprotective mechanisms of curcumin (50 mg/kg, for six weeks) against ethanol (5 mg/kg i.p., for six weeks) induced oxidative stress and inflammation-mediated cognitive dysfunction in mice. According to our findings, ethanol triggered reactive oxygen species (ROS), apoptosis, neuroinflammation, and memory impairment, which were significantly inhibited with the administration of curcumin, as assessed by ROS, lipid peroxidation (LPO), and Nrf2/HO-1 (nuclear factor erythroid 2-related factor 2/Heme-oxygenase-1) expression in the experimental mice brains. Moreover, curcumin regulated the expression of the glial cell markers in ethanol-treated mice brains, as analyzed by the relative expression TLR4 (Toll like Receptor 4), RAGE (Receptor for Advanced Glycations End products), GFAP (Glial fibrillary acidic protein), and Iba-1 (Ionized calcium binding adaptor molecule 1), through Western blot and confocal microscopic analysis. Moreover, our results showed that curcumin downregulated the expression of p-JNK (Phospo c-Jun N-Terminal Kinase), p-NF-kB (nuclear factor kappa-light-chain-enhancer of activated B cells), and its downstream targets, as assessed by Western blot and confocal microscopic analysis. Finally, the expression of synaptic proteins and the behavioral results also supported the hypothesis that curcumin may inhibit memory dysfunction and behavioral alterations associated with ethanol intoxication. Altogether, to the best of our knowledge, we believe that curcumin may serve as a potential, promising, and cheaply available neuroprotective compound against ethanol-associated neurodegenerative diseases.

Genetic Influences on the Amount of Cell Death in the Neural Tube of BXD Mice Exposed to Acute Ethanol at Midgestation

BACKGROUND

Fetal alcohol spectrum disorders (FASD) have a strong genetic component although the genes that underlie this are only beginning to be elucidated. In the present study, one of the most common phenotypes of FASD, cell death within the early developing neural tube, was examined across a genetic reference population in a reverse genetics paradigm with the goal of identifying genetic loci that could influence ethanol (EtOH)-induced apoptosis in the early developing neural tube.

METHODS

BXD recombinant inbred mice as well as the parental strains were used to evaluate genetic differences in EtOH-induced cell death after exposure on embryonic day 9.5. Dams were given either 5.8 g/kg EtOH or isocaloric maltose-dextrin in 2 doses via intragastric gavage. Embryos were collected 7 hours after the initial exposure and cell death evaluated via TUNEL staining in the brainstem and forebrain. Genetic loci were evaluated using quantitative trait locus (QTL) analysis at GeneNetwork.org.

RESULTS

Significant strain differences were observed in the levels of EtOH-induced cell death that were due to genetic effects and not confounding variables such as differences in developmental maturity or cell death kinetics. Comparisons between the 2 regions of the developing neural tube showed little genetic correlation with the QTL maps exhibiting no overlap. Significant QTLs were found on murine mid-chromosome 4 and mid-chromosome 14 only in the brainstem. Within these chromosomal loci, a number of interesting candidate genes were identified that could mediate this differential sensitivity including Nfia (nuclear factor I/A) and Otx2 (orthodenticle homeobox 2).

CONCLUSIONS

These studies demonstrate that the levels of EtOH-induced cell death occur in strain- and region-dependent manners. Novel QTLs on mouse Chr4 and Chr14 were identified that modulate the differential sensitivity to EtOH-induced apoptosis in the embryonic brainstem. The genes underlying these QTLs could identify novel molecular pathways that are critical in this phenotype.

Social Environment and Epigenetics

Our social environment, from the microscopic to the macro-social, affects us for the entirety of our lives. One integral line of research to examine how interpersonal and societal environments can get "under the skin" is through the lens of epigenetics. Epigenetic mechanisms are adaptations made to our genome in response to our environment which include tags placed on and removed from the DNA itself to how our DNA is packaged, affecting how our genes are read, transcribed, and interact. These tags are affected by social environments and can persist over time; this may aid us in responding to experiences and exposures, both the enriched and the disadvantageous. From memory formation to immune function, the experience-dependent plasticity of epigenetic modifications to micro- and macro-social environments may contribute to the process of learning from comfort, pain, and stress to better survive in whatever circumstances life has in store.

Prenatal Alcohol Exposure: Profiling Developmental DNA Methylation Patterns in Central and Peripheral Tissues

Background: Prenatal alcohol exposure (PAE) can alter the development of neurobiological systems, leading to lasting neuroendocrine, neuroimmune, and neurobehavioral deficits. Although the etiology of this reprogramming remains unknown, emerging evidence suggests DNA methylation as a potential mediator and biomarker for the effects of PAE due to its responsiveness to environmental cues and relative stability over time. Here, we utilized a rat model of PAE to examine the DNA methylation profiles of rat hypothalami and leukocytes at four time points during early development to assess the genome-wide impact of PAE on the epigenome and identify potential biomarkers of PAE. Our model of PAE resulted in blood alcohol levels of ~80-150 mg/dl throughout the equivalent of the first two trimesters of human pregnancy. Hypothalami were analyzed on postnatal days (P) 1, 8, 15, 22 and leukocytes at P22 to compare central and peripheral markers. Genome-wide DNA methylation analysis was performed by methylated DNA immunoprecipitation followed by next-generation sequencing. Results: PAE resulted in lasting changes to DNA methylation profiles across all four ages, with 118 differentially methylated regions (DMRs) displaying persistent alterations across the developmental period at a false-discovery rate (FDR) < 0.05. In addition, 299 DMRs showed the same direction of change in the hypothalamus and leukocytes of P22 pups at an FDR < 0.05, with some genes overlapping with the developmental profile findings. The majority of these DMRs were located in intergenic regions, which contained several computationally-predicted transcription factor binding sites. Differentially methylated genes were generally involved in immune function, epigenetic remodeling, metabolism, and hormonal signaling, as determined by gene ontology analyses. Conclusions: Persistent DNA methylation changes in the hypothalamus may be associated with the long-term physiological and neurobehavioral alterations in observed in PAE. Furthermore, correlations between epigenetic alterations in peripheral tissues and those in the brain will provide a foundation for the development of biomarkers of fetal alcohol spectrum disorder (FASD). Finally, findings from studies of PAE provide important insight into the etiology of neurodevelopmental and mental health disorders, as they share numerous phenotypes and comorbidities.

Regional Patterns of Alcohol-Induced Neuronal Loss Depend on Genetics: Implications for Fetal Alcohol Spectrum Disorder

BACKGROUND

Alcohol exposure during pregnancy can kill developing neurons and lead to fetal alcohol spectrum disorder (FASD). However, affected individuals differ in their regional patterns of alcohol-induced neuropathology. Because neuroprotective genes are expressed in spatially selective ways, their mutation could increase the vulnerability of some brain regions, but not others, to alcohol teratogenicity. The objective of this study was to determine whether a null mutation of neuronal nitric oxide synthase (nNOS) can increase the vulnerability of some brain regions, but not others, to alcohol-induced neuronal losses.

METHODS

Immunohistochemistry identified brain regions in which nNOS is present or absent throughout postnatal development. Mice genetically deficient for nNOS (nNOS^-/- ) and wild-type controls received alcohol (0.0, 2.2, or 4.4 mg/g/d) over postnatal days (PD) 4 to 9. Mice were sacrificed in adulthood (~PD 115), and surviving neurons in the olfactory bulb granular layer and brain stem facial nucleus were quantified stereologically.

RESULTS

nNOS was expressed throughout postnatal development in olfactory bulb granule cells but was never expressed in the facial nucleus. In wild-type mice, alcohol reduced neuronal survival to similar degrees in both cell populations. However, null mutation of nNOS more than doubled alcohol-induced cell death in the olfactory bulb granule cells, while the mutation had no effect on the facial nucleus neurons. As a result, in nNOS^-/- mice, alcohol caused substantially more cell loss in the olfactory bulb than in the facial nucleus.

CONCLUSIONS

Mutation of the nNOS gene substantially increases vulnerability to alcohol-induced cell loss in a brain region where the gene is expressed (olfactory bulb), but not in a separate brain region, where the gene is not expressed (facial nucleus). Thus, differences in genotype may explain why some individuals are vulnerable to FASD, while others are not, and may determine the specific patterns of neuropathology in children with FASD.

Short-Term Genetic Selection for Adolescent Locomotor Sensitivity to Delta9-Tetrahydrocannabinol (THC)

Cannabis use is linked to positive and negative outcomes. Identifying genetic targets of susceptibility to the negative effects of cannabinoid use is of growing importance. The current study sought to complete short-term selective breeding for adolescent sensitivity and resistance to the locomotor effects of a single 10 mg/kg THC dose in the open field. Selection for THC-locomotor sensitivity was moderately heritable, with the greatest estimates of heritability seen in females from the F2 to S3 generations. Selection for locomotor sensitivity also resulted in increased anxiety-like activity in the open field. These results are the first to indicate that adolescent THC-locomotor sensitivity can be influenced via selective breeding. Development of lines with a genetic predisposition for THC-sensitivity or resistance to locomotor effects allow for investigation of risk factors, differences in consequences of THC use, identification of correlated behavioral responses, and detection of genetic targets that may contribute to heightened cannabinoid sensitivity.

Acute and long-term effects of Δ9-tetrahydrocannabinol on object recognition and anxiety-like activity are age- and strain-dependent in mice

Use of exogenous cannabinoids disrupts the fine-tuned endocannabinoid receptor system, possibly leading to alterations in cognition, memory, and emotional processes that endure long after cannabinoid use has stopped. Long-term adolescent use may uniquely disrupt these behaviors when compared to adult use. The current study explored the acute and long-term behavioral effects of six 10mg/kg Δ9-tetrahydrocannabinol (THC) injections across the adolescent or early adult period in male inbred C57Bl/6J and DBA/2J mice. The acute and prolonged effects of THC on object memory using the novel object recognition task, unconditioned anxiety in the elevated plus maze and open field, and sedative effects in the open field were examined. Acute THC treatment resulted in anxiogenic activity in both strains, but only caused sedation in B6 mice. Repeated THC treatment resulted in a protracted effect on object recognition, but not unconditioned anxiety, assessed 4weeks later. In both strains, an adolescent history of THC treatment disrupted later object recognition. Interestingly, in B6 mice an adult history of THC exposure appeared to rescue a deficit in object recognition observed in vehicle-treated adults. Repeated THC administration also produced a protracted effected on CB1R protein expression. Animals treated with THC in adolescence maintained increased levels of CB1R protein expression compared to their adult THC-treated counterparts at five weeks following the last injection. These results indicate that THC use may have long-lasting effects with adolescence being a unique period of susceptibility.

Genome-wide profiling of differentially spliced mRNAs in human fetal cortical tissue exposed to alcohol

Excessive alcohol consumption results in significant changes in gene expression and isoforms due to altered mRNA splicing. As such, an intriguing possibility is that disturbances in alternative splicing are involved in key pathological pathways triggered by alcohol exposure. However, no resources have been available to systematically analyze this possibility at a genome-wide scale. Here, we performed RNA sequencing of human fetal cortical slices that were obtained at the late first trimester and exposed to ethanol or control medium. We report 382 events that were identified as changes affecting the ratio of splicing isoforms in the ethanol-exposed fetal human cortex. Additionally, previously unreported novel isoforms of several genes were also identified. These results provide a broad perspective on the post-transcriptional regulatory network underlying ethanol-induced pathogenesis in the developing human cortex.

The effect of alcohol on the differential expression of cluster of differentiation 14 gene, associated pathways, and genetic network

Alcohol consumption affects human health in part by compromising the immune system. In this study, we examined the expression of the Cd14 (cluster of differentiation 14) gene, which is involved in the immune system through a proinflammatory cascade. Expression was evaluated in BXD mice treated with saline or acute 1.8 g/kg i.p. ethanol (12.5% v/v). Hippocampal gene expression data were generated to examine differential expression and to perform systems genetics analyses. The Cd14 gene expression showed significant changes among the BXD strains after ethanol treatment, and eQTL mapping revealed that Cd14 is a cis-regulated gene. We also identified eighteen ethanol-related phenotypes correlated with Cd14 expression related to either ethanol responses or ethanol consumption. Pathway analysis was performed to identify possible biological pathways involved in the response to ethanol and Cd14. We also constructed a genetic network for Cd14 using the top 20 correlated genes and present several genes possibly involved in Cd14 and ethanol responses based on differential gene expression. In conclusion, we found Cd14, along with several other genes and pathways, to be involved in ethanol responses in the hippocampus, such as increased susceptibility to lipopolysaccharides and neuroinflammation.

Changes to histone modifications following prenatal alcohol exposure: An emerging picture

Epigenetic mechanisms are important for facilitating gene-environment interactions in many disease etiologies, including Fetal Alcohol Spectrum Disorders (FASD). Extensive research into the role of DNA methylation and miRNAs in animal models has illuminated the complex role of these mechanisms in FASD. In contrast, histone modifications have not been as well researched, due in part to being less stable than DNA methylation and less well-characterized in disease. It is now apparent that even changes in transient marks can have profound effects if they alter developmental trajectories. In addition, many histone methylations are now known to be relatively stable and can propagate themselves. As technologies and knowledge have advanced, a small group has investigated the role of histone modifications in FASD. Here, we synthesize the data on the effects of prenatal alcohol exposure (PAE) on histone modifications. Several key points are evident. AS with most alcohol-induced outcomes, timing and dosage differences yield variable effects. Nevertheless, these studies consistently find enrichment of H3K9ac, H3K27me2,3, and H3K9me2, and increased expression of histone acetyltransferases and methyltransferases. The consistency of these alterations may implicate them as key mechanisms underlying FASD. Histone modification changes do not often correlate with gene expression changes, though some important examples exist. Encouragingly, attempts to reproduce specific histone modification changes are very often successful. We comment on possible directions for future studies, focusing on further exploration of current trends, expansion of time-point and dosage regimes, and evaluation of biomarker potential.

Epigenetics studies of fetal alcohol spectrum disorder: where are we now?

Adverse in utero events can alter the development and function of numerous physiological systems, giving rise to lasting neurodevelopmental deficits. In particular, data have shown that prenatal alcohol exposure can reprogram neurobiological systems, altering developmental trajectories and resulting in increased vulnerability to adverse neurobiological, behavioral and health outcomes. Increasing evidence suggests that epigenetic mechanisms are potential mediators for the reprogramming of neurobiological systems, as they may provide a link between the genome, environmental conditions and neurodevelopmental outcomes. This review outlines the current state of epigenetic research in fetal alcohol spectrum disorder, highlighting the role of epigenetic mechanisms in the reprogramming of neurobiological systems by alcohol and as potential diagnostic tools for fetal alcohol spectrum disorder. We also present an assessment of the current limitations in studies of prenatal alcohol exposure, and highlight the future steps needed in the field.

Identification of Multiple QTLs Linked to Neuropathology in the Engrailed-1 Heterozygous Mouse Model of Parkinson's Disease

Motor symptoms in Parkinson’s disease are attributed to degeneration of midbrain dopaminergic neurons (DNs). Heterozygosity for Engrailed-1 (En1), one of the key factors for programming and maintenance of DNs, results in a parkinsonian phenotype featuring progressive degeneration of DNs in substantia nigra pars compacta (SNpc), decreased striatal dopamine levels and swellings of nigro-striatal axons in the SwissOF1-En1+/− mouse strain. In contrast, C57Bl/6-En1+/− mice do not display this neurodegenerative phenotype, suggesting that susceptibility to En1 heterozygosity is genetically regulated. Our goal was to identify quantitative trait loci (QTLs) that regulate the susceptibility to PD-like neurodegenerative changes in response to loss of one En1 allele. We intercrossed SwissOF1-En1+/− and C57Bl/6 mice to obtain F2 mice with mixed genomes and analyzed number of DNs in SNpc and striatal axonal swellings in 120 F2-En1+/− 17 week-old male mice. Linkage analyses revealed 8 QTLs linked to number of DNs (p = 2.4e-09, variance explained = 74%), 7 QTLs linked to load of axonal swellings (p = 1.7e-12, variance explained = 80%) and 8 QTLs linked to size of axonal swellings (p = 7.0e-11, variance explained = 74%). These loci should be of prime interest for studies of susceptibility to Parkinson’s disease-like damage in rodent disease models and considered in clinical association studies in PD.