Developmental Ethanol-Induced Sleep Fragmentation, Behavioral Hyperactivity, Cognitive Impairment and Parvalbumin Cell Loss are Prevented by Lithium Co-treatment

Impact of Developmental Alcohol Exposure on Sleep Physiology

The present chapter summarizes the clinical and preclinical findings collected to date, showing the impact of developmental alcohol exposure on sleep physiology. Sleep is a complex physiological process that plays a pivotal role in maintaining overall health and well-being via its involvement in regulating physiological, cognitive, and emotional functions. Clinical studies consistently report a high prevalence of sleep disturbances in children and adolescents diagnosed with fetal alcohol spectrum disorders (FASDs), including short sleep duration, sleep anxiety, bedtime resistance, increased sleep fragmentation, and parasomnias. It is established that alcohol consumption during gestation impairs brain development, leading to structural and functional alterations that may affect sleep architecture. In addition, clinical investigations have found a significant correlation between sleep-wake cycle disruptions and cognitive impairments after developmental alcohol exposure, and sleep disturbances are increasingly recognized as a substantial problem among FASD patients. However, the molecular mechanisms underlying these disturbances are poorly understood. Surprisingly, few studies with animal models of FASDs have characterized the effect of developmental ethanol exposure on sleep physiology, and these have focused on high doses. This chapter provides an overview of the current knowledge, reports the sleep disturbances in FASD patients, and then summarizes the gap in understanding the molecular and physiological mechanisms.

Developmental alcohol exposure is exhausting: Sleep and the enduring consequences of alcohol exposure during development

Prenatal alcohol exposure is the leading nongenetic cause of human intellectual impairment. The long-term impacts of prenatal alcohol exposure on health and well-being are diverse, including neuropathology leading to behavioral, cognitive, and emotional impairments. Additionally negative effects also occur on the physiological level, such as the endocrine, cardiovascular, and immune systems. Among these diverse impacts is sleep disruption. In this review, we describe how prenatal alcohol exposure affects sleep, and potential mechanisms of those effects. Furthermore, we outline the evidence that sleep disruption across the lifespan may be a mediator of some cognitive and behavioral impacts of developmental alcohol exposure, and thus may represent a promising target for treatment.

Binge-like ethanol exposure during the brain growth spurt disrupts the function of retrosplenial cortex-projecting anterior thalamic neurons in adolescent mice

Ethanol (EtOH) exposure during late pregnancy leads to enduring impairments in learning and memory that may stem from damage to components of the posterior limbic memory system, including the retrosplenial cortex (RSC) and anterior thalamic nuclei (ATN). In rodents, binge-like EtOH exposure during the first week of life (equivalent to the third trimester of human pregnancy) triggers apoptosis in these brain regions. We hypothesized that this effect induces long-lasting alterations in the function of RSC-projecting ATN neurons. To test this hypothesis, vesicular GABA transporter-Venus mice (expressing fluorescently tagged GABAergic interneurons) were subjected to binge-like EtOH vapor exposure on postnatal day (P) 7. This paradigm activated caspase 3 in the anterodorsal (AD), anteroventral (AV), and reticular thalamic nuclei at P7 but did not reduce neuronal density in these areas at P60-70. At P40-60, we injected red retrobeads into the RSC and performed patch-clamp slice electrophysiological recordings from retrogradely labeled neurons in the AD and AV nuclei 3-4 days later. We found significant effects of treatment on instantaneous action potential (AP) frequency and AP overshoot, as well as sex × treatment interactions for AP threshold and overshoot in AD neurons. A sex × treatment interaction was detected for AP number in AV neurons. EtOH exposure also reduced the frequency and amplitude of spontaneous excitatory postsynaptic currents and increased the charge transfer of spontaneous inhibitory postsynaptic currents. These results highlight a novel cellular mechanism that could contribute to the lasting learning and memory deficits associated with developmental EtOH exposure.

Homeostatic NREM sleep and salience network function in adult mice exposed to ethanol during development

Developmental exposure to ethanol is a leading cause of cognitive, emotional and behavioral problems, with fetal alcohol spectrum disorder (FASD) affecting more than 1:100 children. Recently, comorbid sleep deficits have been highlighted in these disorders, with sleep repair a potential therapeutic target. Animal models of FASD have shown non-REM (NREM) sleep fragmentation and slow-wave oscillation impairments that predict cognitive performance. Here we use a mouse model of perinatal ethanol exposure to explore whether reduced sleep pressure may contribute to impaired NREM sleep, and compare the function of a brain network reported to be impacted by insomnia-the Salience network-in developmental ethanol-exposed mice with sleep-deprived, saline controls. Mice were exposed to ethanol or saline on postnatal day 7 (P7) and allowed to mature to adulthood for testing. At P90, telemetered cortical recordings were made for assessment of NREM sleep in home cage before and after 4 h of sleep deprivation to assess basal NREM sleep and homeostatic NREM sleep response. To assess Salience network functional connectivity, mice were exposed to the 4 h sleep deprivation period or left alone, then immediately sacrificed for immunohistochemical analysis of c-Fos expression. The results show that developmental ethanol severely impairs both normal rebound NREM sleep and sleep deprivation induced increases in slow-wave activity, consistent with reduced sleep pressure. Furthermore, the Salience network connectome in rested, ethanol-exposed mice was most similar to that of sleep-deprived, saline control mice, suggesting a sleep deprivation-like state of Salience network function after developmental ethanol even without sleep deprivation.

Net gain and loss: influence of natural rewards and drugs of abuse on perineuronal nets

Overindulgence, excessive consumption, and a pattern of compulsive use of natural rewards, such as certain foods or drugs of abuse, may result in the development of obesity or substance use disorder, respectively. Natural rewards and drugs of abuse can trigger similar changes in the neurobiological substrates that drive food- and drug-seeking behaviors. This review examines the impact natural rewards and drugs of abuse have on perineuronal nets (PNNs). PNNs are specialized extracellular matrix structures that ensheathe certain neurons during development over the critical period to provide synaptic stabilization and a protective microenvironment for the cells they surround. This review also analyzes how natural rewards and drugs of abuse impact the density and maturation of PNNs within reward-associated circuitry of the brain, which may contribute to maladaptive food- and drug-seeking behaviors. Finally, we evaluate the relatively few studies that have degraded PNNs to perturb reward-seeking behaviors. Taken together, this review sheds light on the complex way PNNs are regulated by natural rewards and drugs and highlights a need for future studies to delineate the molecular mechanisms that underlie the modification and maintenance of PNNs following exposure to rewarding stimuli.

Somatostatin neuron contributions to cortical slow wave dysfunction in adult mice exposed to developmental ethanol

Introduction

Transitions between sleep and waking and sleep-dependent cortical oscillations are heavily dependent on GABAergic neurons. Importantly, GABAergic neurons are especially sensitive to developmental ethanol exposure, suggesting a potential unique vulnerability of sleep circuits to early ethanol. In fact, developmental ethanol exposure can produce long-lasting impairments in sleep, including increased sleep fragmentation and decreased delta wave amplitude. Here, we assessed the efficacy of optogenetic manipulations of somatostatin (SST) GABAergic neurons in the neocortex of adult mice exposed to saline or ethanol on P7, to modulate cortical slow-wave physiology.

Methods

SST-cre × Ai32 mice, which selectively express channel rhodopsin in SST neurons, were exposed to ethanol or saline on P7. This line expressed similar developmental ethanol induced loss of SST cortical neurons and sleep impairments as C57BL/6By mice. As adults, optical fibers were implanted targeting the prefrontal cortex (PFC) and telemetry electrodes were implanted in the neocortex to monitor slow-wave activity and sleep-wake states.

Results

Optical stimulation of PFC SST neurons evoked slow-wave potentials and long-latency single-unit excitation in saline treated mice but not in ethanol mice. Closed-loop optogenetic stimulation of PFC SST neuron activation on spontaneous slow-waves enhanced cortical delta oscillations, and this manipulation was more effective in saline mice than P7 ethanol mice.

Discussion

Together, these results suggest that SST cortical neurons may contribute to slow-wave impairment after developmental ethanol.

Effects of retinoic acid receptor α modulators on developmental ethanol-induced neurodegeneration and neuroinflammation

Ethanol exposure in neonatal mice induces acute neurodegeneration followed by long-lasting glial activation and GABAergic cell deficits along with behavioral abnormalities, providing a third trimester model of fetal alcohol spectrum disorders (FASD). Retinoic acid (RA), the active form of vitamin A, regulates transcription of RA-responsive genes and plays essential roles in the development of embryos and their CNS. Ethanol has been shown to disturb RA metabolism and signaling in the developing brain, which may be a cause of ethanol toxicity leading to FASD. Using an agonist and an antagonist specific to RA receptor α (RARα), we studied how RA/RARα signaling affects acute and long-lasting neurodegeneration and activation of phagocytic cells and astrocytes caused by ethanol administered to neonatal mice. We found that an RARα antagonist (BT382) administered 30 min before ethanol injection into postnatal day 7 (P7) mice partially blocked acute neurodegeneration as well as elevation of CD68-positive phagocytic cells in the same brain area. While an RARα agonist (BT75) did not affect acute neurodegeneration, BT75 given either before or after ethanol administration ameliorated long-lasting astrocyte activation and GABAergic cell deficits in certain brain regions. Our studies using Nkx2.1-Cre;Ai9 mice, in which major GABAergic neurons and their progenitors in the cortex and the hippocampus are labeled with constitutively expressed tdTomato fluorescent protein, indicate that the long-lasting GABAergic cell deficits are mainly caused by P7 ethanol-induced initial neurodegeneration. However, the partial reduction of prolonged GABAergic cell deficits and glial activation by post-ethanol BT75 treatment suggests that, in addition to the initial cell death, there may be delayed cell death or disturbed development of GABAergic cells, which is partially rescued by BT75. Since RARα agonists including BT75 have been shown to exert anti-inflammatory effects, BT75 may rescue GABAergic cell deficits by reducing glial activation/neuroinflammation.

Neonatal ethanol causes profound reduction of cholinergic cell number in the basal forebrain of adult animals

In animal models that mimic human third-trimester fetal development, ethanol causes substantial cellular apoptosis in the brain, but for most brain structures, the extent of permanent neuron loss that persists into adulthood is unknown. We injected ethanol into C57BL/6J mouse pups at postnatal day 7 (P7) to model human late-gestation ethanol toxicity, and then used stereological methods to investigate adult cell numbers in several subcortical neurotransmitter systems that project extensively in the forebrain to regulate arousal states. Ethanol treatment caused especially large reductions (34-42%) in the cholinergic cells of the basal forebrain, including cholinergic cells in the medial septal/vertical diagonal band nuclei (Ch1/Ch2) and in the horizontal diagonal band/substantia innominata/nucleus basalis nuclei (Ch3/Ch4). Cell loss was also present in non-cholinergic basal forebrain cells, as demonstrated by 34% reduction of parvalbumin-immunolabeled GABA cells and 25% reduction of total Nissl-stained neurons in the Ch1/Ch2 region. In contrast, cholinergic cells in the striatum were reduced only 12% by ethanol, and those of the brainstem pedunculopontine/lateral dorsal tegmental nuclei (Ch5/Ch6) were not significantly reduced. Similarly, ethanol did not significantly reduce dopamine cells of the ventral tegmental area/substantia nigra or serotonin cells in the dorsal raphe nucleus. Orexin (hypocretin) cells in the hypothalamus showed a modest reduction (14%). Our findings indicate that the basal forebrain is especially vulnerable to alcohol exposure in the late gestational period. Reduction of cholinergic and GABAergic projection neurons from the basal forebrain that regulate forebrain arousal may contribute to the behavioral and cognitive deficits associated with neonatal ethanol exposure.

Parvalbumin Interneurons and Perineuronal Nets in the Hippocampus and Retrosplenial Cortex of Adult Male Mice After Early Social Isolation Stress and Perinatal NMDA Receptor Antagonist Treatment

Both early life aversive experiences and intrinsic alterations in early postnatal neurodevelopment are considered predisposing factors for psychiatric disorders, such as schizophrenia. The prefrontal cortex and the hippocampus have protracted postnatal development and are affected in schizophrenic patients. Interestingly, similar alterations have been observed in the retrosplenial cortex (RSC). Studies in patients and animal models of schizophrenia have found alterations in cortical parvalbumin (PV) expressing interneurons, making them good candidates to study the etiopathology of this disorder. Some of the alterations observed in PV+ interneurons may be mediated by perineuronal nets (PNNs), specialized regions of the extracellular matrix, which frequently surround these inhibitory neurons. In this study, we have used a double hit model (DHM) combining a single perinatal injection of an NMDAR antagonist (MK801) to disturb early postnatal development and post-weaning social isolation as an early life aversive experience. We have investigated PV expressing interneurons and PNNs in the hippocampus and the RSC of adult male mice, using unbiased stereology. In the CA1, but not in the CA3 region, of the hippocampus, the number of PNNs and PV + PNN+ cells was affected by the drug treatment, and a significant decrease of these parameters was observed in the groups of animals that received MK801. The percentage of PNNs surrounding PV+ cells was significantly decreased after treatment in both hippocampal regions; however, the impact of isolation was observed only in CA1, where isolated animals presented lower percentages. In the RSC, we observed significant effects of isolation, MK801 and the interaction of both interventions on the studied parameters; in the DHM, we observed a significantly lower number of PV+, PNNs, and PV+PNN+cells when compared to control mice. Similar significant decreases were observed for the groups of animals that were just isolated or treated with MK801. To our knowledge, this is the first report on such alterations in the RSC in an animal model combining neurodevelopmental alterations and aversive experiences during infancy/adolescence. These results show the impact of early-life events on different cortical regions, especially on the structure and plasticity of PV+ neurons and their involvement in the emergence of certain psychiatric disorders.

Extracellular Vesicles in Premature Aging and Diseases in Adulthood Due to Developmental Exposures

The developmental origins of health and disease (DOHaD) is a paradigm that links prenatal and early life exposures that occur during crucial periods of development to health outcome and risk of disease later in life. Maternal exposures to stress, some psychoactive drugs and alcohol, and environmental chemicals, among others, may result in functional changes in developing fetal tissues, creating a predisposition for disease in the individual as they age. Extracellular vesicles (EVs) may be mediators of both the immediate effects of exposure during development and early childhood as well as the long-term consequences of exposure that lead to increased risk and disease severity later in life. Given the prevalence of diseases with developmental origins, such as cardiovascular disease, neurodegenerative disorders, osteoporosis, metabolic dysfunction, and cancer, it is important to identify persistent mediators of disease risk. In this review, we take this approach, viewing diseases typically associated with aging in light of early life exposures and discuss the potential role of EVs as mediators of lasting consequences.

Molecular signature of extracellular matrix pathology in schizophrenia

Growing evidence points to a critical involvement of the extracellular matrix (ECM) in the pathophysiology of schizophrenia (SZ). Decreases of perineuronal nets (PNNs) and altered expression of chondroitin sulphate proteoglycans (CSPGs) in glial cells have been identified in several brain regions. GWAS data have identified several SZ vulnerability variants of genes encoding for ECM molecules. Given the potential relevance of ECM functions to the pathophysiology of this disorder, it is necessary to understand the extent of ECM changes across brain regions, their region- and sex-specificity and which ECM components contribute to these changes. We tested the hypothesis that the expression of genes encoding for ECM molecules may be broadly disrupted in SZ across several cortical and subcortical brain regions and include key ECM components as well as factors such as ECM posttranslational modifications and regulator factors. Gene expression profiling of 14 neocortical brain regions, caudate, putamen and hippocampus from control subjects (n = 14/region) and subjects with SZ (n = 16/region) was conducted using Affymetrix microarray analysis. Analysis across brain regions revealed widespread dysregulation of ECM gene expression in cortical and subcortical brain regions in SZ, impacting several ECM functional key components. SRGN, CD44, ADAMTS1, ADAM10, BCAN, NCAN and SEMA4G showed some of the most robust changes. Region-, sex- and age-specific gene expression patterns and correlation with cognitive scores were also detected. Taken together, these findings contribute to emerging evidence for large-scale ECM dysregulation in SZ and point to molecular pathways involved in PNN decreases, glial cell dysfunction and cognitive impairment in SZ.

Enhancement of parvalbumin interneuron-mediated neurotransmission in the retrosplenial cortex of adolescent mice following third trimester-equivalent ethanol exposure

Prenatal ethanol exposure causes a variety of cognitive deficits that have a persistent impact on quality of life, some of which may be explained by ethanol-induced alterations in interneuron function. Studies from several laboratories, including our own, have demonstrated that a single binge-like ethanol exposure during the equivalent to the third trimester of human pregnancy leads to acute apoptosis and long-term loss of interneurons in the rodent retrosplenial cortex (RSC). The RSC is interconnected with the hippocampus, thalamus, and other neocortical regions and plays distinct roles in visuospatial processing and storage, as well as retrieval of hippocampal-dependent episodic memories. Here we used slice electrophysiology to characterize the acute effects of ethanol on GABAergic neurotransmission in the RSC of neonatal mice, as well as the long-term effects of neonatal ethanol exposure on parvalbumin-interneuron mediated neurotransmission in adolescent mice. Mice were exposed to ethanol using vapor inhalation chambers. In postnatal day (P) 7 mouse pups, ethanol unexpectedly failed to potentiate GABA_A receptor-mediated synaptic transmission. Binge-like ethanol exposure of P7 mice expressing channel rhodopsin in parvalbumin-positive interneurons enhanced the peak amplitudes, asynchronous activity and total charge, while decreasing the rise-times of optically-evoked GABA_A receptor-mediated inhibitory postsynaptic currents in adolescent animals. These effects could partially explain the learning and memory deficits that have been documented in adolescent and young adult mice exposed to ethanol during the third trimester-equivalent developmental period.

Ameliorating Effects of Lithium on the Perinatal Ethanol-Induced Behavioral and Cognitive Dysfunction and Brain Oxidative Stress in Postnatal Developing Mice Pups

BACKGROUND

Developmental ethanol (EtOH) exposure can cause lifelong behavioral hyperactivity, cognitive deficits, emotional dysregulation, and more. However, co-treatment with lithium (Li) on the day of EtOH exposure prevents many of the impairments.

METHODS

Experimental groups of pregnant mice were exposed to EtOH (20% v/v solution at a dose of 2.5 g/kg) in their drinking water and the animals were treated with Li (15 and 30 mg/kg) through IP injection on gestational days14, 16, 18, and 20, and post-natal days (PD) 3, 5, 7, and 9. All treatments with EtOH and exposure to Li doses to pregnant mice started on gestational day 14 and continued until post-natal day 9 (PD9). The effects on some developing morphological indices, nerve reflexes during weaning age, and various cognitive dysfunctions at adolescent ages and biochemical changes in the brain tissue indices of below-mentioned neurotransmitters and oxidative stress in post-natal developing offspring at adolescent age, were studied.

RESULTS

Perinatal exposure to EtOH in pregnant mice resulted in several postnatal developing and morphological indices in the developing male pups during their weaning period, like gain in their body weight, delay in appearance of their body hair fuzz and opening of their eyes, and disruptions in their developing motor reflexes.

DISCUSSION

During adolescent age, a significant deficit in their learning capability and cognitive behavior, decline in the neurochemical DA and 5-HT in their brain and some indices of oxidative stress TBARS, GSH, GST, CAT, and SOD was observed.

CONCLUSION

These results indicate that Li ameliorates significantly and dose-dependently EtOH induced developmental toxicities like morphological developments and dysfunctions in cognitive retention and oxidative stress on a long-term basis in brain tissue. However, further detailed studies are required for the clinical use of as an ameliorating agent for perinatal EtOH induced dysfunctions.

Post-exposure environment modulates long-term developmental ethanol effects on behavior, neuroanatomy, and cortical oscillations

Developmental exposure to ethanol has a wide range of anatomical, cellular, physiological and behavioral impacts that can last throughout life. In humans, this cluster of effects is termed fetal alcohol spectrum disorder and is highly prevalent in western cultures. The ultimate expression of the effects of developmental ethanol exposure however can be influenced by post-exposure experience. Here we examined the effects of developmental binge exposure to ethanol (postnatal day 7) in C57BL/6By mice on a specific cohort of inter-related long-term outcomes including contextual memory, hippocampal parvalbumin-expressing neuron density, frontal cortex oscillations related to sleep-wake cycling including delta oscillation amplitude and sleep spindle density, and home-cage behavioral activity. When assessed in adults that were raised in standard housing, all of these factors were altered by early ethanol exposure compared to saline controls except home-cage activity. However, exposure to an enriched environment and exercise from weaning to postnatal day 90 reversed most of these ethanol-induced impairments including memory, CA1 but not dentate gyrus PV+ cell density, delta oscillations and sleep spindles, and enhanced home-cage behavioral activity in Saline- but not EtOH-treated mice. The results are discussed in terms of the inter-dependence of diverse developmental ethanol outcomes and potential mechanisms of post-exposure experiences to regulate those outcomes.

Early Life Trauma Has Lifelong Consequences for Sleep And Behavior

Sleep quality varies widely across individuals, especially during normal aging, with impaired sleep contributing to deficits in cognition and emotional regulation. Sleep can also be impacted by a variety of adverse events, including childhood adversity. Here we examined how early life adverse events impacted later life sleep structure and physiology using an animal model to test the relationship between early life adversity and sleep quality across the life span. Rat pups were exposed to an Adversity-Scarcity model from postnatal day 8–12, where insufficient bedding for nest building induces maternal maltreatment of pups. Polysomnography and sleep physiology were assessed in weaning, early adult and older adults. Early life adversity induced age-dependent disruptions in sleep and behavior, including lifelong spindle decreases and later life NREM sleep fragmentation. Given the importance of sleep in cognitive and emotional functions, these results highlight an important factor driving variation in sleep, cognition and emotion throughout the lifespan that suggest age-appropriate and trauma informed treatment of sleep problems.

Neonatal ethanol exposure triggers apoptosis in the murine retrosplenial cortex: Role of inhibition of NMDA receptor-driven action potential firing

Exposure to ethanol during the last trimester equivalent of human pregnancy causes apoptotic neurodegeneration in the developing brain, an effect that is thought to be mediated, in part, by inhibition of NMDA receptors. However, NMDA receptors can rapidly adapt to the acute effects of ethanol and are ethanol resistant in some populations of developing neurons. Here, we characterized the effect of ethanol on NMDA and non-NMDA receptor-mediated synaptic transmission in the retrosplenial cortex (RSC), a brain region involved in the integration of different modalities of spatial information that is among the most sensitive regions to ethanol-induced neurodegeneration. A single 4-h exposure to ethanol vapor of 7-day-old transgenic mice that express the Venus fluorescent protein in interneurons triggered extensive apoptosis in the RSC. Slice electrophysiological recordings showed that bath-applied ethanol inhibits NMDA and non-NMDA receptor excitatory postsynaptic currents (EPSCs) in pyramidal neurons and interneurons; however, we found no evidence of acute tolerance development to this effect after the 4-h in-vivo ethanol vapor exposure. Acute bath application of ethanol reduced action potential firing evoked by synaptic stimulation to a greater extent in pyramidal neurons than interneurons. Submaximal inhibition of NMDA EPSCs, but not non-NMDA EPSCs, mimicked the acute effect of ethanol on synaptically-evoked action potential firing. These findings indicate that partial inhibition of NMDA receptors by ethanol has sizable effects on the excitability of glutamatergic and GABAergic neurons in the developing RSC, and suggest that positive allosteric modulators of these receptors could ameliorate ethanol intoxication-induced neurodegeneration during late stages of fetal development.

Exposure of Hyperandrogen During Pregnancy Causes Depression- and Anxiety-Like Behaviors, and Reduced Hippocampal Neurogenesis in Rat Offspring

The hippocampus is a region in which neurogenesis persists and retains substantial plasticity throughout lifespan. Accumulating evidences indicate an important role of androgens and androgenic signaling in the regulation of offspring hippocampal neurogenesis and the survival of mature or immature neurons and gliocyte. Hyperandrogenic disorders have been associated with depression and anxiety. Previous studies have found that pregnant hyperandrogenism may increase the susceptibility of the offspring to depression or anxiety and lead to abnormal hippocampal neurogenesis in rats. In this study, pregnant rats were given subcutaneous injection of aromatase inhibitor letrozole in order to establish a maternal hyperandrogenic environment for the fetal rats. The lithium chloride (LICl) was used as an intervention agent since a previous study has shown that lithium chloride could promote neurogenesis in the hippocampus. The results revealed that pregnant administration of letrozole resulted in depressive- and anxious-like behaviors in the adolescent period. A remarkable decrease in immature nerve cells marked by doublecortin and mature neurons co-expressed by Brdu and NeuN in adult years were detected in the hippocampal dentate gyrus of adolescent rats. Lithium chloride alleviated the effects on neurobehavioral and promoted the differentiation and proliferation of neural progenitor cells, while a hyperandrogenic intrauterine environment had no effects on astrocytes marked by GFAP in the dentate gyrus. Furthermore, the Wnt/β-catenin signaling pathway related to normal development of hippocampus was examined but there was no significant changes in Wnt signaling pathway members. Our study provides evidence that exposure of androgen during pregnancy leads to alterations in depressive, anxious and stereotypical behaviors and these phenotypes are possibly associated with changes in neurogenesis in the dentate gyrus.

Effects of neonatal ethanol on cerebral cortex development through adolescence

Neonatal brain lesions cause deficits in structure and function of the cerebral cortex that sometimes are not fully expressed until adolescence. To better understand the onset and persistence of changes caused by postnatal day 7 (P7) ethanol treatment, we examined neocortical cell numbers, volume, surface area and thickness from neonatal to post-adolescent ages. In control mice, total neuron number decreased from P8 to reach approximately stable levels at about P30, as expected from normal programmed cell death. Cortical thickness reached adult levels by P14, but cortical volume and surface area continued to increase from juvenile (P20-30) to post-adolescent (P54-93) ages. P7 ethanol caused a reduction of total neurons by P14, but this deficit was transient, with later ages having only small and non-significant reductions. Previous studies also reported transient neuron loss after neonatal lesions that might be partially explained by an acute acceleration of normally occurring programmed cell death. GABAergic neurons expressing parvalbumin, calretinin, or somatostatin were reduced by P14, but unlike total neurons the reductions persisted or increased in later ages. Cortical volume, surface area and thickness were also reduced by P7 ethanol. Cortical volume showed evidence of a transient reduction at P14, and then was reduced again in post-adolescent ages. The results show a developmental sequence of neonatal ethanol effects. By juvenile ages the cortex overcomes the P14 deficit of total neurons, whereas P14 GABA cell deficits persist. Cortical volume reductions were present at P14, and again in post-adolescent ages.

Role of MCP-1 and CCR2 in alcohol neurotoxicity

Alcohol abuse causes profound damage to both the developing brain and the adult brain. Prenatal exposure to alcohol results in a wide range of deficits known as fetal alcohol spectrum disorders (FASD). Alcohol abuse in adults is associated with brain shrinkage, memory and attention deficits, communication disorders and physical disabilities. Monocyte chemoattractant protein-1 (MCP-1/CCL2) is one of the key chemokines that regulate the recruitment and activation of monocytes and microglia. Both MCP-1 and its receptor C-C chemokine receptor type 2 (CCR2) expressed in the brain are involved in various neuroinflammatory disorders, such as multiple sclerosis (MS), Alzheimer's disease (AD) and Parkinson's disease (PD). However, the role of MCP-1/CCR2 in alcohol-induced brain damage is unclear. Recent evidence indicates that alcohol exposure increased the activity of MCP-1/CCR2 in both mature and developing central nervous systems (CNS). MCP-1/CCR2 signaling in the brain was involved in alcohol drinking behavior. MCP-1/CCR2 inhibition alleviated alcohol neurotoxicity by reducing microglia activation/neuroinflammation in the developing brain and spinal cord. In this review, we discussed the role of MCP-1/CCR2 signaling in alcohol-induced neuroinflammation and brain damage. We also discussed the signaling cascades that are involved in the activation of MCP-1/CCR2 in response to alcohol exposure.