Perinatal Ischemia Alters Global Expression of Synaptosomal Proteins Critical for Neural Plasticity in the Developing Mouse Brain.

Ischemic perinatal stroke (IPS) affects 1 in 2,300-5,000 live births. Despite a survival rate >95%, approximately 60% of IPS infants develop motor and cognitive impairments. Given the importance of axonal growth and synaptic plasticity in neurocognitive development, our objective was to identify the molecular pathways underlying IPS-associated synaptic dysfunction using a mouse model. IPS was induced by unilateral ligation of the common carotid artery of postnatal day 10 (P10) mice. Five days after ischemia, sensorimotor and motor functions were assessed by vibrissae-evoked forepaw placement and the tail suspension test respectively, showing evidence of greater impairments in male pups than in female pups. Twenty-four hours after ischemia, both hemispheres were collected and synaptosomal proteins then prepared for quantification, using isobaric tags for relative and absolute quantitation. Seventy-two of 1,498 qualified proteins were altered in the ischemic hemisphere. Ingenuity Pathway Analysis was used to map these proteins onto molecular networks indicative of reduced neuronal proliferation, survival, and synaptic plasticity, accompanied by reduced PKCα signaling in male, but not female, pups. These effects also occurred in the non-ischemic hemisphere when compared with sham controls. The altered signaling effects may contribute to the sex-specific neurodevelopmental dysfunction following IPS, highlighting potential pathways for targeting during treatment.

Early-Life Iron Deficiency Anemia Programs the Hippocampal Epigenomic Landscape.

Iron deficiency (ID) anemia is the foremost micronutrient deficiency worldwide, affecting around 40% of pregnant women and young children. ID during the prenatal and early postnatal periods has a pronounced effect on neurodevelopment, resulting in long-term effects such as cognitive impairment and increased risk for neuropsychiatric disorders. Treatment of ID has been complicated as it does not always resolve the long-lasting neurodevelopmental deficits. In animal models, developmental ID results in abnormal hippocampal structure and function associated with dysregulation of genes involved in neurotransmission and synaptic plasticity. Dysregulation of these genes is a likely proximate cause of the life-long deficits that follow developmental ID. However, a direct functional link between iron and gene dysregulation has yet to be elucidated. Iron-dependent epigenetic modifications are one mechanism by which ID could alter gene expression across the lifespan. The jumonji and AT-rich interaction domain-containing (JARID) protein and the Ten-Eleven Translocation (TET) proteins are two families of iron-dependent epigenetic modifiers that play critical roles during neural development by establishing proper gene regulation during critical periods of brain development. Therefore, JARIDs and TETs can contribute to the iron-mediated epigenetic mechanisms by which early-life ID directly causes stable changes in gene regulation across the life span.

Prenatal Iron Deficiency and Choline Supplementation Interact to Epigenetically Regulate Jarid1b and Bdnf in the Rat Hippocampus into Adulthood.

Early-life iron deficiency (ID) causes long-term neurocognitive impairments and gene dysregulation that can be partially mitigated by prenatal choline supplementation. The long-term gene dysregulation is hypothesized to underlie cognitive dysfunction. However, mechanisms by which iron and choline mediate long-term gene dysregulation remain unknown. In the present study, using a well-established rat model of fetal-neonatal ID, we demonstrated that ID downregulated hippocampal expression of the gene encoding JmjC-ARID domain-containing protein 1B (JARID1B), an iron-dependent histone H3K4 demethylase, associated with a higher histone deacetylase 1 (HDAC1) enrichment and a lower enrichment of acetylated histone H3K9 (H3K9ac) and phosphorylated cAMP response element-binding protein (pCREB). Likewise, ID reduced transcriptional capacity of the gene encoding brain-derived neurotrophic factor (BDNF), a target of JARID1B, associated with repressive histone modifications such as lower H3K9ac and pCREB enrichments at the Bdnf promoters in the adult rat hippocampus. Prenatal choline supplementation did not prevent the ID-induced chromatin modifications at these loci but induced long-lasting repressive chromatin modifications in the iron-sufficient adult rats. Collectively, these findings demonstrated that the iron-dependent epigenetic mechanism mediated by JARID1B accounted for long-term Bdnf dysregulation by early-life ID. Choline supplementation utilized a separate mechanism to rescue the effect of ID on neural gene regulation. The negative epigenetic effects of choline supplementation in the iron-sufficient rat hippocampus necessitate additional investigations prior to its use as an adjunctive therapeutic agent.

Perinatal Lead (Pb) Exposure and Cortical Neuron-Specific DNA Methylation in Male Mice.

: Lead (Pb) exposure is associated with a wide range of neurological deficits. Environmental exposures may impact epigenetic changes, such as DNA methylation, and can affect neurodevelopmental outcomes over the life-course. Mating mice were obtained from a genetically invariant C57BL/6J background agouti viable yellow Avy strain. Virgin dams (a/a) were randomly assigned 0 ppm (control), 2.1 ppm (low), or 32 ppm (high) Pb-acetate water two weeks prior to mating with male mice (Avy/a), and this continued through weaning. At age 10 months, cortex neuronal nuclei were separated with NeuN⁺ antibodies in male mice to investigate neuron-specific genome-wide promoter DNA methylation using the Roche NimbleGen Mouse 3x720K CpG Island Promoter Array in nine pooled samples (three per dose). Several probes reached p-value < 10-5 , all of which were hypomethylated: 12 for high Pb (minimum false discovery rate (FDR) = 0.16, largest intensity ratio difference = -2.1) and 7 for low Pb (minimum FDR = 0.56, largest intensity ratio difference = -2.2). Consistent with previous results in bulk tissue, we observed a weak association between early-life exposure to Pb and DNA hypomethylation, with some affected genes related to neurodevelopment or cognitive function. Although these analyses were limited to males, data indicate that non-dividing cells such as neurons can be carriers of long-term epigenetic changes induced in development.

Impact of amplitude-integrated electroencephalograms on clinical care for neonates with seizures.

Amplitude-integrated electroencephalography (aEEG) was recently introduced into neonatal intensive care in the United States. We evaluated whether aEEG has changed clinical care for neonates with seizures. This study included all 202 neonates treated for seizures at our hospital from 2002-2007. Neonates monitored with aEEG (n = 67) were compared with contemporary control neonates who were not monitored, despite the availability of aEEG (n = 57), and a historic control group of neonates treated for seizures before our neonatal intensive care unit initiated aEEG (n = 78). Eighty-two percent of those receiving phenobarbital (137/167) continued treatment after discharge, with no difference among groups. Adjusted for gestational age and length of stay, no difference among groups was evident in number of neuroimaging studies or number of antiepileptic drugs per patient. Fewer patients undergoing aEEG, compared with contemporary (16/67 vs 29/57, respectively, P = 0.001) or historic (n = 38/78, P = 0.002) controls, were diagnosed clinically with seizures without electrographic confirmation. We conclude that aEEG did not increase neuroimaging tests, and did not alter antiepileptic drug use. However, diagnostic precision regarding neonatal seizures improved with aEEG because fewer neonates were treated for seizures based solely on clinical findings, without electrographic confirmation.

Prevalence and risk factors for vitamin D insufficiency among children with epilepsy.

This cross-sectional study was designed to determine the prevalence of, and risk factors for, vitamin D insufficiency among children treated for epilepsy in a general pediatric neurology clinic. Included were 78 children with epilepsy, aged 3-17 years, treated by the authors between September 2008 and March 2009. Vitamin D levels and relevant risk factors were evaluated using multiple logistic regression. Of the 78 children, 41% were male and 81% were of European origin; the mean age was 11.64 + or - 4.37 years. 25-hydroxyvitamin D levels of <20 ng/mL were observed in 25% of the children and levels considered to be normal (>32 ng/mL) were observed in only 25%. Girls and children with elevated body mass index were at increased risk for low 25-hydroxyvitamin D. The odds ratio for low 25-hydroxyvitamin D was 4.07 for girls versus boys, with a 95% confidence interval of 1.18-13.97; for each 1-unit increase in body mass index, the odds ratio was 1.179, with a 95% confidence interval of 1.047-1.329. Use of newer antiepileptic drugs was not associated with altered risk, compared with older enzyme-inducing drugs. Vitamin D insufficiency was highly prevalent in this unselected population of children with epilepsy. Female sex and increased body mass index were significant risk factors for low vitamin D levels, but antiepileptic drug regimen was not.