Chronic ethanol exposure causes mitochondrial dysfunction and oxidative stress in immature central nervous system neurons

Young Age and Concomitant Cannabis (THC) and Ethanol (EtOH) Exposure Enhances Rat Brain Damage Through Decreased Cerebral Mitochondrial Respiration

The reason why young people taking concomitantly cannabis (THC) and ethanol (EtOH) are more prone to stroke is underresearched. To investigate whether an underlying mechanism of increased brain damage could be an impaired mitochondrial function, this experiment determined the acute effects of EtOH, both alone and associated with THC, on mitochondrial respiration and oxidative stress (hydrogen peroxide H2O2) on young (11 weeks) and middle-aged (45 weeks) brain in rats, using a high-resolution oxygraph (Oxygraph-2K, Oroboros instruments). In young brains, EtOH decreased mitochondrial respiration by -51.76 ± 2.60% (from 32.76 ± 3.82 to 17.41 ± 1.42 pmol/s/mL, p < 0.0001). In 45-week-old brains, the decrease was lesser, but still significant -36.0 ± 2.80% (from 30.73 ± 7.72 to 20.59 ± 5.48 pmol/s/mL, p < 0.0001). Concomitant THC aggravated brain mitochondrial respiration decreases at 11 weeks (-86.86 ± 1.74%, p < 0.0001) and at 45 weeks (-73.95 ± 3.69%, p < 0.0001). Such additional injury was enhanced in young brains (p < 0.01). H2O2 production was similar in both age groups (1.0 ± 0.2 versus 1.1 ± 0.08 pmol O2/s/mL) and was not modified by THC addition. In conclusion, EtOH alone significantly impairs brain mitochondrial respiration and concomitant THC further aggravates such damage, particularly in young brains. These data support the hypothesis that enhanced mitochondrial dysfunction might participate in the increased occurrence of stroke in the young and urge for better prevention against EtOH and THC addictions in adolescents.

Differential effects of moderate chronic ethanol consumption on neurobehavior, white matter glial protein expression, and mTOR pathway signaling with adolescent brain maturation

Background: Adolescent brains are highly vulnerable to heavy alcohol exposure. Increased understanding of how alcohol adversely impacts brain maturation may improve treatment outcomes.Objectives: This study characterizes short-term versus long-term effects of ethanol feeding on behavior, frontal lobe glial proteins, and mTOR signaling.Methods: Adolescent rats (8/group) were fed liquid diets containing 26% or 0% ethanol for 2 or 9 weeks, then subjected to novel object recognition (NOR) and open field (OF) tests. Frontal lobes were used for molecular assays.Results: Significant ethanol effects on OF performance occurred in the 2-week model (p < .0001). Further shifts in OF and NOR performance were unrelated to ethanol exposure in the 9-week models (p < .05 to p < .0001). Ethanol inhibited MAG1 (p < .01) and MBP (p < .0001) after 2 but not 9 weeks. However, both control and ethanol 9-week models had significantly reduced MAG1 (p < .001-0.0001), MBP (p < .0001), PDGFRA (p < .05-0.01), and PLP (p < .001-0.0001) relative to the 2-week models. GFAP was the only glial protein significantly inhibited by ethanol in both 2- (p < .01) and 9-week (p < .05) models. Concerning the mTOR pathway, ethanol reduced IRS-1 (p < .05) and globally inhibited mTOR (p < .01 or p < .001) in the 9- but not the 2-week model.Conclusions: Short-term versus long-term ethanol exposures differentially alter neurobehavioral function, glial protein expression, and signaling through IRS-1 and mTOR, which have known roles in myelination during adolescence. These findings suggest that strategies to prevent chronic alcohol-related brain pathology should consider the increased maturation-related vulnerability of adolescent brains.

Emerging paradigms: unmasking the role of oxidative stress in HPV-induced carcinogenesis

The contribution of the human papillomavirus (HPV) to cancer is significant but not exclusive, as carcinogenesis involves complex mechanisms, notably oxidative stress. Oxidative stress and HPV can independently cause genome instability and DNA damage, contributing to tumorigenesis. Oxidative stress-induced DNA damage, especially double-strand breaks, aids in the integration of HPV into the host genome and promotes the overexpression of two viral proteins, E6 and E7. Lifestyle factors, including diet, smoking, alcohol, and psychological stress, along with genetic and epigenetic modifications, and viral oncoproteins may influence oxidative stress, impacting the progression of HPV-related cancers. This review highlights various mechanisms in oxidative-induced HPV-mediated carcinogenesis, including altered mitochondrial morphology and function leading to elevated ROS levels, modulation of antioxidant enzymes like Superoxide Dismutase (SOD), Glutathione (GSH), and Glutathione Peroxidase (GPx), induction of chronic inflammatory environments, and activation of specific cell signaling pathways like the Phosphoinositide 3-kinase, Protein kinase B, Mammalian target of rapamycin (PI3K/AKT/mTOR) and the Extracellular signal-regulated kinase (ERK) signaling pathway. The study highlights the significance of comprehending and controlling oxidative stress in preventing and treating cancer. We suggested that incorporating dietary antioxidants and targeting cancer cells through mechanisms involving ROS could be potential interventions to mitigate the impact of oxidative stress on HPV-related malignancies.

The Impact of Prenatal Alcohol Exposure on Longitudinal Growth, Nutritional Status, and Insulin-Like Growth Factor 1 in Early Childhood in Leyte, the Philippines

OBJECTIVE

To assess the impact and potential mechanistic pathways of prenatal alcohol exposure (PAE) on longitudinal growth and nutritional status in early childhood.

STUDY DESIGN

A cohort of 296 mother-infant dyads (32% with PAE vs 68% unexposed) were recruited in Leyte, the Philippines, and followed from early gestation through 24 months of age. PAE was assessed using serum phosphatidylethanol (PEth) captured twice prenatally and in cord blood and supplemented with self-reported alcohol consumption. Linear mixed models were used to examine longitudinal effects of PAE on growth from birth through 2 years including key potential mediating factors (placental histopathology, and infant serum leptin and Insulin-like Growth Factor 1 [IGF-1]).

RESULTS

After adjusting for potential confounders, we found that PAE was significantly associated with a delayed blunting of linear growth trajectories (height-for-age z-score, body length) and weight (weight-for-age z-score, body weight) that manifested between 4 and 6 months and continued through 12-24 months. PAE was also associated with a decreased rate of mid-upper-arm circumference growth from birth to 12 months, and a lower mean IGF-1 levels at birth and 6 months.

CONCLUSION

This study demonstrates a delayed impact of PAE on growth that manifested around 6 months of age, underscoring the importance of routine clinical monitoring in early childhood. Furthermore, the findings supported prior animal model findings that suggest a mechanistic role for IGF-1 in PAE-induced growth delay.

The Impact of Oxidative Stress on the Epigenetics of Fetal Alcohol Spectrum Disorders

Fetal alcohol spectrum disorders (FASD) represent a continuum of lifelong impairments resulting from prenatal exposure to alcohol, with significant global impact. The "spectrum" of disorders includes a continuum of physical, cognitive, behavioral, and developmental impairments which can have profound and lasting effects on individuals throughout their lives, impacting their health, social interactions, psychological well-being, and every aspect of their lives. This narrative paper explores the intricate relationship between oxidative stress and epigenetics in FASD pathogenesis and its therapeutic implications. Oxidative stress, induced by alcohol metabolism, disrupts cellular components, particularly in the vulnerable fetal brain, leading to aberrant development. Furthermore, oxidative stress is implicated in epigenetic changes, including alterations in DNA methylation, histone modifications, and microRNA expression, which influence gene regulation in FASD patients. Moreover, mitochondrial dysfunction and neuroinflammation contribute to epigenetic changes associated with FASD. Understanding these mechanisms holds promise for targeted therapeutic interventions. This includes antioxidant supplementation and lifestyle modifications to mitigate FASD-related impairments. While preclinical studies show promise, further clinical trials are needed to validate these interventions' efficacy in improving clinical outcomes for individuals affected by FASD. This comprehensive understanding of the role of oxidative stress in epigenetics in FASD underscores the importance of multidisciplinary approaches for diagnosis, management, and prevention strategies. Continued research in this field is crucial for advancing our knowledge and developing effective interventions to address this significant public health concern.

Synaptic and mitochondrial mechanisms behind alcohol-induced imbalance of excitatory/inhibitory synaptic activity and associated cognitive and behavioral abnormalities

Alcohol consumption during pregnancy can significantly impact the brain development of the fetus, leading to long-term cognitive and behavioral problems. However, the underlying mechanisms are not well understood. In this study, we investigated the acute and chronic effects of binge-like alcohol exposure during the third trimester equivalent in postnatal day 7 (P7) mice on brain cell viability, synapse activity, cognitive and behavioral performance, and gene expression profiles at P60. Our results showed that alcohol exposure caused neuroapoptosis in P7 mouse brains immediately after a 6-hour exposure. In addition, P60 mice exposed to alcohol during P7 displayed impaired learning and memory abilities and anxiety-like behaviors. Electrophysiological analysis of hippocampal neurons revealed an excitatory/inhibitory imbalance in alcohol-treated P60 mice compared to controls, with decreased excitation and increased inhibition. Furthermore, our bioinformatic analysis of 376 dysregulated genes in P60 mouse brains following alcohol exposure identified 50 synapse-related and 23 mitochondria-related genes. These genes encoded proteins located in various parts of the synapse, synaptic cleft, extra-synaptic space, synaptic membranes, or mitochondria, and were associated with different biological processes and functions, including the regulation of synaptic transmission, transport, synaptic vesicle cycle, metabolism, synaptogenesis, mitochondrial activity, cognition, and behavior. The dysregulated synapse and mitochondrial genes were predicted to interact in overlapping networks. Our findings suggest that altered synaptic activities and signaling networks may contribute to alcohol-induced long-term cognitive and behavioral impairments in mice, providing new insights into the underlying synaptic and mitochondrial molecular mechanisms and potential neuroprotective strategies.

Agent Orange Causes Metabolic Dysfunction and Molecular Pathology Reminiscent of Alzheimer's Disease

Background

Agent Orange, an herbicide used during the Vietnam War, contains 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). Agent Orange has teratogenic and carcinogenic effects, and population-based studies suggest Agent Orange exposures lead to higher rates of toxic and degenerative pathologies in the peripheral and central nervous system (CNS).

Objective

This study examines the potential contribution of Agent Orange exposures to neurodegeneration.

Methods

Human CNS-derived neuroepithelial cells (PNET2) treated with 2,4-D and 2,4,5-T were evaluated for viability, mitochondrial function, and Alzheimer's disease (AD)-related proteins.

Results

Treatment with 250μg/ml 2,4-D or 2,4,5-T significantly impaired mitochondrial function, caused degenerative morphological changes, and reduced viability in PNET2 cells. Correspondingly, glyceraldehyde-3-phosphate dehydrogenase expression which is insulin-regulated and marks the integrity of carbohydrate metabolism, was significantly inhibited while 4-hydroxy-2-nonenal, a marker of lipid peroxidation, was increased. Tau neuronal cytoskeletal protein was significantly reduced by 2,4,5-T, and relative tau phosphorylation was progressively elevated by 2,4,5-T followed by 2,4-D treatment relative to control. Amyloid-β protein precursor (AβPP) was increased by 2,4,5-T and 2,4-D, and 2,4,5-T caused a statistical trend (0.05 < p<0.10) increase in Aβ. Finally, altered cholinergic function due to 2,4,5-T and 2,4-D exposures was marked by significantly increased choline acetyltransferase and decreased acetylcholinesterase expression, corresponding with responses in early-stage AD.

Conclusion

Exposures to Agent Orange herbicidal chemicals rapidly damage CNS neurons, initiating a path toward AD-type neurodegeneration. Additional research is needed to understand the permanency of these neuropathologic processes and the added risks of developing AD in Agent Orange-exposed aging Vietnam Veterans.

Loss of Nicotinamide nucleotide transhydrogenase sensitizes embryos to ethanol-induced neural crest and neural apoptosis via generation of reactive oxygen species

Fetal alcohol spectrum disorders (FASD) are a continuum of birth defects caused by prenatal alcohol exposure. FASD are the most common environmentally induced birth defect and are highly variable. The genetics of an individual influence the severity of their FASD phenotype. However, the genes that sensitize an individual to ethanol-induced birth defects are largely unknown. The ethanol-sensitive mouse substrain, C57/B6J, carries several known mutations including one in Nicotinamide nucleotide transhydrogenase (Nnt). Nnt is a mitochondrial transhydrogenase thought to have an important role in detoxifying reactive oxygen species (ROS) and ROS has been implicated in ethanol teratogenesis. To directly test the role of Nnt in ethanol teratogenesis, we generated zebrafish nnt mutants via CRISPR/Cas9. Zebrafish embryos were dosed with varying concentrations of ethanol across different timepoints and assessed for craniofacial malformations. We utilized a ROS assay to determine if this could be a contributing factor of these malformations. We found that exposed and unexposed mutants had higher levels of ROS compared to their wildtype counterparts. When treated with ethanol, nnt mutants experienced elevated apoptosis in the brain and neural crest, a defect that was rescued by administration of the antioxidant, N-acetyl cysteine (NAC). NAC treatment also rescued most craniofacial malformations. Altogether this research demonstrates that ethanol-induced oxidative stress leads to craniofacial and neural defects due to apoptosis in nnt mutants. This research further supports the growing body of evidence implicating oxidative stress in ethanol teratogenesis. These findings suggest that antioxidants can be used as a potential therapeutic in the treatment of FASD.

Sexual Dimorphism in the Expression of Cardiac and Hippocampal Renin-Angiotensin and Kallikrein–Kinin Systems in Offspring from Mice Exposed to Alcohol during Gestation

Prenatal alcohol exposure (PAE) impairs fetal development. Alcohol consumption was shown to modulate the renin–angiotensin system (RAS). This study aimed to analyze the effects of PAE on the expression of the renin–angiotensin system (RAS) and kallikrein–kinin system (KKS) peptide systems in the hippocampus and heart of mice of both sexes. C57Bl/6 mice were exposed to alcohol during pregnancy at a concentration of 10% (v/v). On postnatal day 45 (PN45), mouse hippocampi and left ventricles (LV) were collected and processed for messenger RNA (mRNA) expression of components of the RAS and KKS. In PAE animals, more pronounced expression of AT1 and ACE mRNAs in males and a restored AT2 mRNA expression in females were observed in both tissues. In LV, increased AT2, ACE2, and B2 mRNA expressions were also observed in PAE females. Furthermore, high levels of H2O2 were observed in males from the PAE group in both tissues. Taken together, our results suggest that modulation of the expression of these peptidergic systems in PAE females may make them less susceptible to the effects of alcohol.

Assessment of Alcohol Exposure From Alcohol-Based Disinfectants Among Premature Infants in Neonatal Incubators in Japan

IMPORTANCE

The risk of premature infants in neonatal incubators exposed to evaporated alcohol from alcohol-based disinfectants (ABDs) is unknown.

OBJECTIVE

To assess alcohol concentrations in the peripheral blood of premature infants and neonatal incubators.

DESIGN, SETTING, AND PARTICIPANTS

A quality improvement study comparing 2 different populations before and after introduction of ABD practice (ABD-PRAC) was conducted in a neonatal intensive care unit of a single tertiary hospital in Japan. Participants included premature infants who were born before 34 weeks of gestational age and received medical care in neonatal incubators. The study consisted of 3 periods: (1) September 1, 2020, to August 1, 2021 (prospective observation of pre-ABD-PRAC, (2) August 2 to August 22, 2021 (introduction of ABD-PRAC to medical staff and parents in the neonatal intensive care unit), and (3) August 23, 2021, to March 31, 2022 (prospective observation of post-ABD-PRAC). No follow-up studies were initiated.

INTERVENTIONS

An ABD-PRAC that aimed to reduce alcohol evaporation from ABDs inside neonatal incubators was instituted: (1) place alcohol preps in the incubator just before use and remove them from the incubator as soon as possible and (2) withhold placing hands into the incubators until 60 seconds after using ABDs for disinfection (applied only to family members).

MAIN OUTCOMES AND MEASURES

Blood alcohol concentration and evaporated alcohol concentrations in neonatal incubators.

RESULTS

Disinfectant practice was assessed among 28 infants during the pre-ABD-PRAC (17 infants [10 girls]; median gestational age at birth, 29.4 [IQR, 26.3-30.3] weeks) and post-ABD-PRAC (11 infants [3 girls]; median gestational age at birth, 30.0 [IQR, 25.3-32.2] weeks) study periods. The median blood alcohol concentration was 7.0 (IQR, 5.4-9.3) mg/dL pre-ABD-PRAC and 4.2 (IQR, 2.5-7.2) mg/dL post-ABD-PRAC. The median evaporated alcohol concentration inside neonatal incubators during pre-ABD-PRAC during the day was 23.6 (IQR, 15.9-36.5) ppm and, at night, was 13.2 (IQR, 8.9-19.4) ppm; during post-ABD-PRAC, the concentration was 9.4 (IQR, 6.0-16.0) ppm during the day and 5.7 (IQR, 3.6-9.7) ppm at night. The introduction of ABD-PRAC at 22 weeks' corrected gestational age was associated with a lower blood alcohol concentration in premature infants: regression coefficient value, -8.3 (95% CI, -12.0 to -4.7).

CONCLUSIONS AND RELEVANCE

In this study, alcohol evaporated from ABDs was absorbed by premature infants in neonatal incubators. The findings suggest that introduction of ABD-PRAC was associated with lower alcohol concentrations in neonatal incubators and in the blood of premature infants.

Chromatin modifier developmental pluripotency associated factor 4 (DPPA4) is a candidate gene for alcohol-induced developmental disorders

BACKGROUND

Prenatal alcohol exposure (PAE) affects embryonic development, causing a variable fetal alcohol spectrum disorder (FASD) phenotype with neuronal disorders and birth defects. We hypothesize that early alcohol-induced epigenetic changes disrupt the accurate developmental programming of embryo and consequently cause the complex phenotype of developmental disorders. To explore the etiology of FASD, we collected unique biological samples of 80 severely alcohol-exposed and 100 control newborns at birth.

METHODS

We performed genome-wide DNA methylation (DNAm) and gene expression analyses of placentas by using microarrays (EPIC, Illumina) and mRNA sequencing, respectively. To test the manifestation of observed PAE-associated DNAm changes in embryonic tissues as well as potential biomarkers for PAE, we examined if the changes can be detected also in white blood cells or buccal epithelial cells of the same newborns by EpiTYPER. To explore the early effects of alcohol on extraembryonic placental tissue, we selected 27 newborns whose mothers had consumed alcohol up to gestational week 7 at maximum to the separate analyses. Furthermore, to explore the effects of early alcohol exposure on embryonic cells, human embryonic stem cells (hESCs) as well as hESCs during differentiation into endodermal, mesodermal, and ectodermal cells were exposed to alcohol in vitro.

RESULTS

DPPA4, FOXP2, and TACR3 with significantly decreased DNAm were discovered-particularly the regulatory region of DPPA4 in the early alcohol-exposed placentas. When hESCs were exposed to alcohol in vitro, significantly altered regulation of DPPA2, a closely linked heterodimer of DPPA4, was observed. While the regulatory region of DPPA4 was unmethylated in both control and alcohol-exposed hESCs, alcohol-induced decreased DNAm similar to placenta was seen in in vitro differentiated mesodermal and ectodermal cells. Furthermore, common genes with alcohol-associated DNAm changes in placenta and hESCs were linked exclusively to the neurodevelopmental pathways in the enrichment analysis, which emphasizes the value of placental tissue when analyzing the effects of prenatal environment on human development.

CONCLUSIONS

Our study shows the effects of early alcohol exposure on human embryonic and extraembryonic cells, introduces candidate genes for alcohol-induced developmental disorders, and reveals potential biomarkers for prenatal alcohol exposure.

Mechanisms Underlying Cognitive Impairment Induced by Prenatal Alcohol Exposure

Alcohol is one of the most commonly used illicit substances among pregnant women. Clinical and experimental studies have revealed that prenatal alcohol exposure affects fetal brain development and ultimately results in the persistent impairment of the offspring's cognitive functions. Despite this, the rate of alcohol use among pregnant women has been progressively increasing. Various aspects of human and animal behavior, including learning and memory, are dependent on complex interactions between multiple mechanisms, such as receptor function, mitochondrial function, and protein kinase activation, which are especially vulnerable to alterations during the developmental period. Thus, the exploration of the mechanisms that are altered in response to prenatal alcohol exposure is necessary to develop an understanding of how homeostatic imbalance and various long-term neurobehavioral impairments manifest following alcohol abuse during pregnancy. There is evidence that prenatal alcohol exposure results in vast alterations in mechanisms such as long-term potentiation, mitochondrial function, and protein kinase activation in the brain of offspring. However, to the best of our knowledge, there are very few recent reviews that focus on the cognitive effects of prenatal alcohol exposure and the associated mechanisms. Therefore, in this review, we aim to provide a comprehensive summary of the recently reported alterations to various mechanisms following alcohol exposure during pregnancy, and to draw potential associations with behavioral changes in affected offspring.

Cellular Bioenergetics: Experimental Evidence for Alcohol-induced Adaptations

At-risk alcohol use is associated with multisystemic effects and end-organ injury, and significantly contributes to global health burden. Several alcohol-mediated mechanisms have been identified, with bioenergetic maladaptation gaining credence as an underlying pathophysiological mechanism contributing to cellular injury. This evidence-based review focuses on the current knowledge of alcohol-induced bioenergetic adaptations in metabolically active tissues: liver, cardiac and skeletal muscle, pancreas, and brain. Alcohol metabolism itself significantly interferes with bioenergetic pathways in tissues, particularly the liver. Alcohol decreases states of respiration in the electron transport chain, and activity and expression of respiratory complexes, with a net effect to decrease ATP content. In addition, alcohol dysregulates major metabolic pathways, including glycolysis, the tricarboxylic acid cycle, and fatty acid oxidation. These bioenergetic alterations are influenced by alcohol-mediated changes in mitochondrial morphology, biogenesis, and dynamics. The review highlights similarities and differences in bioenergetic adaptations according to tissue type, pattern of (acute vs. chronic) alcohol use, and energy substrate availability. The compromised bioenergetics synergizes with other critical pathophysiological mechanisms, including increased oxidative stress and accelerates cellular dysfunction, promoting senescence, programmed cell death, and end-organ injury.

Transgenerational Abnormalities Induced by Paternal Preconceptual Alcohol Drinking: Findings from Humans and Animal Models

Alcohol consumption during pregnancy and lactation is a widespread preventable cause of neurodevelopmental impairment in newborns. While the harmful effects of gestational alcohol use have been well documented, only recently, the role of paternal preconceptual alcohol consumption (PPAC) prior to copulating has drawn specific epigenetic considerations. Data from human and animal models have demonstrated that PPAC may affect sperm function, eliciting oxidative stress. In newborns, PPAC may induce changes in behavior, cognitive functions, and emotional responses. Furthermore, PPAC may elicit neurobiological disruptions, visuospatial impairments, hyperactivity disorders, motor skill disruptions, hearing loss, endocrine, and immune alterations, reduced physical growth, placental disruptions, and metabolic alterations. Neurobiological studies on PPAC have also disclosed changes in brain function and structure by disrupting the growth factors pathways. In particular, as shown in animal model studies, PPAC alters brain nerve growth factor (NGF) and brainderived neurotrophic factor (BDNF) synthesis and release. This review shows that the crucial topic of lifelong disabilities induced by PPAC and/or gestational alcohol drinking is quite challenging at the individual, societal, and familial levels. Since a nontoxic drinking behavior before pregnancy (for both men and women), during pregnancy, and lactation cannot be established, the only suggestion for couples planning pregnancies is to completely avoid the consumption of alcoholic beverages.

Anti-inflammatory, Antioxidant, and Antiapoptotic Action of Metformin Attenuates Ethanol Neurotoxicity in the Animal Model of Fetal Alcohol Spectrum Disorders

Fetal alcohol exposure has permanent effects on the brain structure, leading to functional deficits in several aspects of behavior, including learning and memory. Alcohol-induced neurocognitive impairment in offsprings is included with activation of oxidative- inflammatory cascade followed with wide apoptotic neurodegeneration in several brain areas, such as the hippocampus. Metformin is the first-line treatment for diabetic patients. It rapidly crosses the blood-brain barrier (BBB) and exerts antioxidant, anti-inflammatory, and neuroprotective effects. In this study, we evaluated the protective effects of metformin on ethanol-related neuroinflammation, as well as neuron apoptosis in the hippocampus of adult male rat in animal model of fetal alcohol spectrum disorders. Treatment with ethanol in milk solution (5.25 and 27.8 g/kg, respectively) was conducted by intragastric intubation at 2-10 days after birth. To examine the antioxidant and anti-inflammatory properties of metformin, an ELISA assay was performed for determining the tumor necrosis factor-α (TNF-α) and antioxidant enzyme concentrations. Immunohistochemical staining was conducted for evaluating the glial fibrillary acidic protein (GFAP) and cleaved caspase-3 expression. Based on the results, metformin caused a significant increase in the superoxide dismutase (SOD) (P < 0.05) and glutathione peroxidase (GSH-Px) (P < 0.01) activities. On the other hand, it reduced the concentrations of TNF-α and malondialdehyde, compared to the ethanol group (P < 0.01). In the metformin group, there was a reduction in cell apoptosis in the hippocampus, as well as GFAP-positive cells (P < 0.01). Overall, apoptotic signaling, regulated by the oxidative inflammatory cascade, can be suppressed by metformin in adult brain rats following animal model of fetal alcohol spectrum disorders.

Alcohol and Head and Neck Cancer: Updates on the Role of Oxidative Stress, Genetic, Epigenetics, Oral Microbiota, Antioxidants, and Alkylating Agents

Head and neck cancer (HNC) concerns more than 890,000 patients worldwide annually and is associated with the advanced stage at presentation and heavy outcomes. Alcohol drinking, together with tobacco smoking, and human papillomavirus infection are the main recognized risk factors. The tumorigenesis of HNC represents an intricate sequential process that implicates a gradual acquisition of genetic and epigenetics alterations targeting crucial pathways regulating cell growth, motility, and stromal interactions. Tumor microenvironment and growth factors also play a major role in HNC. Alcohol toxicity is caused both directly by ethanol and indirectly by its metabolic products, with the involvement of the oral microbiota and oxidative stress; alcohol might enhance the exposure of epithelial cells to carcinogens, causing epigenetic modifications, DNA damage, and inaccurate DNA repair with the formation of DNA adducts. Long-term markers of alcohol consumption, especially those detected in the hair, may provide crucial information on the real alcohol drinking of HNC patients. Strategies for prevention could include food supplements as polyphenols, and alkylating drugs as therapy that play a key role in HNC management. Indeed, polyphenols throughout their antioxidant and anti-inflammatory actions may counteract or limit the toxic effect of alcohol whereas alkylating agents inhibiting cancer cells' growth could reduce the carcinogenic damage induced by alcohol. Despite the established association between alcohol and HNC, a concerning pattern of alcohol consumption in survivors of HNC has been shown. It is of primary importance to increase the awareness of cancer risks associated with alcohol consumption, both in oncologic patients and the general population, to provide advice for reducing HNC prevalence and complications.

Aversive Learning Deficits and Depressive-Like Behaviors Are Accompanied by an Increase in Oxidative Stress in a Rat Model of Fetal Alcohol Spectrum Disorders: The Protective Effect of Rapamycin

Fetal alcohol spectrum disorders (FASDs) are one of the most common consequences of ethanol exposure during pregnancy. In adulthood, these disorders can be manifested by learning and memory deficits and depressive-like behavior. Ethanol-induced oxidative stress may be one of the factors that induces FASD development. The mammalian target of the Rapamycin (mTOR) signaling pathway that acts via two distinct multiprotein complexes, mTORC1 and mTORC2, can affect oxidative stress. We investigated whether mTOR-dependent or mTOR-independent mechanisms are engaged in this phenomenon. Thus, Rapamycin—a selective inhibitor of mTORC1, Torin-2—a non-selective mTORC1/mTORC2 inhibitor, and FK-506—a drug that impacts oxidative stress in an mTOR-independent manner were used. Behavioral tests were performed in adult (PND60-65) rats using a passive avoidance (PA) task (aversive learning and memory) and forced swimming test (FST) (depressive-like behaviors). In addition, the biochemical parameters of oxidative stress, such as lipid peroxidation (LPO), as well as apurinic/apyrimidinic (AP)-sites were determined in the hippocampus and prefrontal cortex in adult (PND65) rats. The rat FASD model was induced by intragastric ethanol (5 g/kg/day) administration at postnatal day (PND)4–9 (an equivalent to the third trimester of human pregnancy). All substances (3 mg/kg) were given 30 min before ethanol. Our results show that neonatal ethanol exposure leads to deficits in context-dependent fear learning and depressive-like behavior in adult rats that were associated with increased oxidative stress parameters in the hippocampus and prefrontal cortex. Because these effects were completely reversed by Rapamycin, an mTORC1 inhibitor, this outcome suggests its usefulness as a preventive therapy in disorders connected with prenatal ethanol exposure.

The Placenta as a Target for Alcohol During Pregnancy: The Close Relation with IGFs Signaling Pathway

Alcohol is one of the most consumed drugs in the world, even during pregnancy. Its use is a risk factor for developing adverse outcomes, e.g. fetal death, miscarriage, fetal growth restriction, and premature birth, also resulting in fetal alcohol spectrum disorders. Ethanol metabolism induces an oxidative environment that promotes the oxidation of lipids and proteins, triggers DNA damage, and advocates mitochondrial dysfunction, all of them leading to apoptosis and cellular injury. Several organs are altered due to this harmful behavior, the brain being one of the most affected. Throughout pregnancy, the human placenta is one of the most important organs for women's health and fetal development, as it secretes numerous hormones necessary for a suitable intrauterine environment. However, our understanding of the human placenta is very limited and even more restricted is the knowledge of the impact of toxic substances in its development and fetal growth. So, could ethanol consumption during this period have wounding effects in the placenta, compromising proper fetal organ development? Several studies have demonstrated that alcohol impairs various signaling cascades within G protein-coupled receptors and tyrosine kinase receptors, mainly through its action on insulin and insulin-like growth factor 1 (IGF-1) signaling pathway. This last cascade is involved in cell proliferation, migration, and differentiation and in placentation. This review tries to examine the current knowledge and gaps in our existing understanding of the ethanol effects in insulin/IGFs signaling pathway, which can explain the mechanism to elucidate the adverse actions of ethanol in the maternal-fetal interface of mammals.

The Inferior Colliculus in Alcoholism and Beyond

Post-mortem neuropathological and in vivo neuroimaging methods have demonstrated the vulnerability of the inferior colliculus to the sequelae of thiamine deficiency as occurs in Wernicke-Korsakoff Syndrome (WKS). A rich literature in animal models ranging from mice to monkeys-including our neuroimaging studies in rats-has shown involvement of the inferior colliculi in the neural response to thiamine depletion, frequently accomplished with pyrithiamine, an inhibitor of thiamine metabolism. In uncomplicated alcoholism (i.e., absent diagnosable neurological concomitants), the literature citing involvement of the inferior colliculus is scarce, has nearly all been accomplished in preclinical models, and is predominately discussed in the context of ethanol withdrawal. Our recent work using novel, voxel-based analysis of structural Magnetic Resonance Imaging (MRI) has demonstrated significant, persistent shrinkage of the inferior colliculus using acute and chronic ethanol exposure paradigms in two strains of rats. We speculate that these consistent findings should be considered from the perspective of the inferior colliculi having a relatively high CNS metabolic rate. As such, they are especially vulnerable to hypoxic injury and may be provide a common anatomical link among a variety of disparate insults. An argument will be made that the inferior colliculi have functions, possibly related to auditory gating, necessary for awareness of the external environment. Multimodal imaging including diffusion methods to provide more accurate in vivo visualization and quantification of the inferior colliculi may clarify the roles of brain stem nuclei such as the inferior colliculi in alcoholism and other neuropathologies marked by altered metabolism.

Modeling alcohol-induced neurotoxicity using human induced pluripotent stem cell-derived three-dimensional cerebral organoids

Maternal alcohol exposure during pregnancy can substantially impact the development of the fetus, causing a range of symptoms, known as fetal alcohol spectrum disorders (FASDs), such as cognitive dysfunction and psychiatric disorders, with the pathophysiology and mechanisms largely unknown. Recently developed human cerebral organoids from induced pluripotent stem cells are similar to fetal brains in the aspects of development and structure. These models allow more relevant in vitro systems to be developed for studying FASDs than animal models. Modeling binge drinking using human cerebral organoids, we sought to quantify the downstream toxic effects of alcohol (ethanol) on neural pathology phenotypes and signaling pathways within the organoids. The results revealed that alcohol exposure resulted in unhealthy organoids at cellular, subcellular, bioenergetic metabolism, and gene expression levels. Alcohol induced apoptosis on organoids. The apoptotic effects of alcohol on the organoids depended on the alcohol concentration and varied between cell types. Specifically, neurons were more vulnerable to alcohol-induced apoptosis than astrocytes. The alcohol-treated organoids exhibit ultrastructural changes such as disruption of mitochondria cristae, decreased intensity of mitochondrial matrix, and disorganized cytoskeleton. Alcohol exposure also resulted in mitochondrial dysfunction and metabolic stress in the organoids as evidenced by (1) decreased mitochondrial oxygen consumption rates being linked to basal respiration, ATP production, proton leak, maximal respiration and spare respiratory capacity, and (2) increase of non-mitochondrial respiration in alcohol-treated organoids compared with control groups. Furthermore, we found that alcohol treatment affected the expression of 199 genes out of 17,195 genes analyzed. Bioinformatic analyses showed the association of these dysregulated genes with 37 pathways related to clinically relevant pathologies such as psychiatric disorders, behavior, nervous system development and function, organismal injury and abnormalities, and cellular development. Notably, 187 of these genes are critically involved in neurodevelopment, and/or implicated in nervous system physiology and neurodegeneration. Furthermore, the identified genes are key regulators of multiple pathways linked in networks. This study extends for the first time animal models of binge drinking-related FASDs to a human model, allowing in-depth analyses of neurotoxicity at tissue, cellular, subcellular, metabolism, and gene levels. Hereby, we provide novel insights into alcohol-induced pathologic phenotypes, cell type-specific vulnerability, and affected signaling pathways and molecular networks, that can contribute to a better understanding of the developmental neurotoxic effects of binge drinking during pregnancy.

Alcohol as an early life stressor: Epigenetics, metabolic, neuroendocrine and neurobehavioral implications

Ethanol exposure during gestation is an early life stressor that profoundly dysregulates structure and functions of the embryonal nervous system, altering the cognitive and behavioral development. Such dysregulation is also achieved by epigenetic mechanisms, which, altering the chromatin structure, redraw the entire pattern of gene expression. In parallel, an oxidative stress response at the cellular level and a global upregulation of neuroendocrine stress response, regulated by the HPA axis, exist and persist in adulthood. This neurobehavioral framework matches those observed in other psychiatric diseases such as mood diseases, depression, autism; those early life stressing events, although probably triggered by specific and different epigenetic mechanisms, give rise to largely overlapping neurobehavioral phenotypes. An early diagnosis of prenatal alcohol exposure, using reliable markers of ethanol intake, together with a deeper understanding of the pathogenic mechanisms, some of them reversible by their nature, can offer a temporal "window" of intervention. Supplementing a mother's diet with protective and antioxidant substances in addition to supportive psychological therapies can protect newborns from being affected.

Murine Models for the Study of Fetal Alcohol Spectrum Disorders: An Overview

Prenatal alcohol exposure is associated to different physical, behavioral, cognitive, and neurological impairments collectively known as fetal alcohol spectrum disorder. The underlying mechanisms of ethanol toxicity are not completely understood. Experimental studies during human pregnancy to identify new diagnostic biomarkers are difficult to carry out beyond genetic or epigenetic analyses in biological matrices. Therefore, animal models are a useful tool to study the teratogenic effects of alcohol on the central nervous system and analyze the benefits of promising therapies. Animal models of alcohol spectrum disorder allow the analysis of key variables such as amount, timing and frequency of ethanol consumption to describe the harmful effects of prenatal alcohol exposure. In this review, we aim to synthetize neurodevelopmental disabilities in rodent fetal alcohol spectrum disorder phenotypes, considering facial dysmorphology and fetal growth restriction. We examine the different neurodevelopmental stages based on the most consistently implicated epigenetic mechanisms, cell types and molecular pathways, and assess the advantages and disadvantages of murine models in the study of fetal alcohol spectrum disorder, the different routes of alcohol administration, and alcohol consumption patterns applied to rodents. Finally, we analyze a wide range of phenotypic features to identify fetal alcohol spectrum disorder phenotypes in murine models, exploring facial dysmorphology, neurodevelopmental deficits, and growth restriction, as well as the methodologies used to evaluate behavioral and anatomical alterations produced by prenatal alcohol exposure in rodents.

What's retinoic acid got to do with it? Retinoic acid regulation of the neural crest in craniofacial and ocular development

Retinoic acid (RA), the active derivative of vitamin A (retinol), is an essential morphogen signaling molecule and major regulator of embryonic development. The dysregulation of RA levels during embryogenesis has been associated with numerous congenital anomalies, including craniofacial, auditory, and ocular defects. These anomalies result from disruptions in the cranial neural crest, a vertebrate-specific transient population of stem cells that contribute to the formation of diverse cell lineages and embryonic structures during development. In this review, we summarize our current knowledge of the RA-mediated regulation of cranial neural crest induction at the edge of the neural tube and the migration of these cells into the craniofacial region. Further, we discuss the role of RA in the regulation of cranial neural crest cells found within the frontonasal process, periocular mesenchyme, and pharyngeal arches, which eventually form the bones and connective tissues of the head and neck and contribute to structures in the anterior segment of the eye. We then review our understanding of the mechanisms underlying congenital craniofacial and ocular diseases caused by either the genetic or toxic disruption of RA signaling. Finally, we discuss the role of RA in maintaining neural crest-derived structures in postembryonic tissues and the implications of these studies in creating new treatments for degenerative craniofacial and ocular diseases.

Alcohol hangover effects on brain cortex non-synaptic mitochondria and synaptosomes bioenergetics

Alcohol hangover (AH) has been associated with oxidative stress and mitochondrial dysfunction. We herein postulate that AH-induced mitochondrial alterations can be due to a different pattern of response in synaptosomes and non-synaptic (NS) mitochondria. Mice received intraperitoneal (i.p.) injections of ethanol (3.8 g/kg) or saline and were sacrificed 6 h afterward. Brain cortex NS mitochondria and synaptosomes were isolated by Ficoll gradient. Oxygen consumption rates were measured in NS mitochondria and synaptosomes by high-resolution respirometry. Results showed that NS-synaptic mitochondria from AH animals presented a 26% decrease in malate-glutamate state 3 respiration, a 64% reduction in ATP content, 28-37% decrements in ATP production rates (malate-glutamate or succinate-dependent, respectively), and 44% inhibition in complex IV activity. No changes were observed in mitochondrial transmembrane potential (ΔΨ) or in UCP-2 expression in NS-mitochondria. Synaptosome respiration driving proton leak (in the presence of oligomycin), and spare respiratory capacity (percentage ratio between maximum and basal respiration) were 30% and 15% increased in hangover condition, respectively. Synaptosomal ATP content was 26% decreased, and ATP production rates were 40-55% decreased (malate-glutamate or succinate-dependent, respectively) in AH mice. In addition, a 24% decrease in ΔΨ and a 21% increase in UCP-2 protein expression were observed in synaptosomes from AH mice. Moreover, mitochondrial respiratory complexes I-III, II-III, and IV activities measured in synaptosomes from AH mice were decreased by 18%, 34%, and 50%, respectively. Results of this study reveal that alterations in bioenergetics status during AH could be mainly due to changes in mitochondrial function at the level of synapses.

Fetal Cerebral Artery Mitochondrion as Target of Prenatal Alcohol Exposure

Prenatal alcohol exposure results in an array of developmental abnormalities known as fetal alcohol spectrum disorders (FASDs). Despite the high prevalence of FASDs, therapeutic interventions against accidental or intended exposure of developing fetuses to alcohol are limited. This review outlines current knowledge about mitochondria in cerebral blood vessels as a potential target for anti-FASDs intervention. First, it describes the multifaceted role of mitochondria in maintaining the cerebral artery diameter as shown in adult tissue. Second, current literature on alcohol-driven damage of mitochondrial morphology and function in several fetal tissues, including liver, heart, and brain is summarized. The functional consequences of alcohol exposure in these organs include morphological enlargement of mitochondria, increased oxidative stress, and alteration of cellular respiration. These studies point to a tissue-specific effect of alcohol on mitochondrial function and a particular vulnerability of fetal mitochondria to alcohol exposure when compared to adult counterparts. Third, recent work from our group describing persistent changes in fetal baboon cerebral artery proteome following three episodes of prenatal alcohol exposure is reviewed. In conclusion, the consequences of prenatal alcohol exposure on cerebral artery mitochondria constitute an open field of investigation and, eventually, a point of therapeutic intervention against FASDs.

Oxidative stress and DNA damage in the mechanism of fetal alcohol spectrum disorders

This review covers molecular mechanisms involving oxidative stress and DNA damage that may contribute to morphological and functional developmental disorders in animal models resulting from exposure to alcohol (ethanol, EtOH) in utero or in embryo culture. Components covered include: (a) a brief overview of EtOH metabolism and embryopathic mechanisms other than oxidative stress; (b) mechanisms within the embryo and fetal brain by which EtOH increases the formation of reactive oxygen species (ROS); (c) critical embryonic/fetal antioxidative enzymes and substrates that detoxify ROS; (d) mechanisms by which ROS can alter development, including ROS-mediated signal transduction and oxidative DNA damage, the latter of which leads to pathogenic genetic (mutations) and epigenetic changes; (e) pathways of DNA repair that mitigate the pathogenic effects of DNA damage; (f) related indirect mechanisms by which EtOH enhances risk, for example by enhancing the degradation of some DNA repair proteins; and, (g) embryonic/fetal pathways like NRF2 that regulate the levels of many of the above components. Particular attention is paid to studies in which chemical and/or genetic manipulation of the above mechanisms has been shown to alter the ability of EtOH to adversely affect development. Alterations in the above components are also discussed in terms of: (a) individual embryonic and fetal determinants of risk and (b) potential risk biomarkers and mitigating strategies. FASD risk is likely increased in progeny which/who are biochemically predisposed via genetic and/or environmental mechanisms, including enhanced pathways for ROS formation and/or deficient pathways for ROS detoxification or DNA repair.

Ethanol exposed maturing rat cerebellar granule cells show impaired energy metabolism and increased cell death after oxygen-glucose deprivation

Alcohol, a widely abused drug, has deleterious effects on the immature nervous system. This study investigates the effect of chronic in vitro ethanol exposure on the metabolism of immature rat cerebellar granular cells (CGCs) and on their response to oxygen-glucose deprivation (OGD). Primary CGC cultures were exposed to ethanol (100 mM in culture medium) or to control ethanol-free medium starting day one in vitro (DIV1). At DIV8, the expression of ATP synthase gene ATP5g3 was quantified using real-time PCR, then cultures were exposed to 3 hours of OGD or normoxic conditions. Subsequently, cellular metabolism was assessed by a resazurin assay and by ATP level measurement. ATP5g3 expression was reduced by 12-fold (P = 0.03) and resazurin metabolism and ATP level were decreased to 74.4 ± 4.6% and 55.5 ± 6.9%, respectively after chronic ethanol treatment compared to control values (P < 0.01). Additionally, after OGD exposure of ethanol-treated cultures, resazurin metabolism and ATP level were decreased to 12.7 ± 1.0% and 9.0 ± 2.0% from control values (P < 0.01). These results suggest that chronic ethanol exposure reduces the cellular ATP level, possibly through a gene expression down-regulation mechanism, and increases the vulnerability to oxygen-glucose deprivation. Thus, interventions which improve metabolic function and sustain ATP-levels could attenuate ethanol-induced neuronal dysfunction and should be addressed in future studies.

Fetal oxidative stress mechanisms of neurodevelopmental deficits and exacerbation by ethanol and methamphetamine

In utero exposure of mouse progeny to alcohol (ethanol, EtOH) and methamphetamine (METH) causes substantial postnatal neurodevelopmental deficits. One emerging pathogenic mechanism underlying these deficits involves fetal brain production of reactive oxygen species (ROS) that alter signal transduction, and/or oxidatively damage cellular macromolecules like lipids, proteins, and DNA, the latter leading to altered gene expression, likely via non-mutagenic mechanisms. Even physiological levels of fetal ROS production can be pathogenic in biochemically predisposed progeny, and ROS formation can be enhanced by drugs like EtOH and METH, via activation/induction of ROS-producing NADPH oxidases (NOX), drug bioactivation to free radical intermediates by prostaglandin H synthases (PHS), and other mechanisms. Antioxidative enzymes, like catalase in the fetal brain, while low, provide critical protection. Oxidatively damaged DNA is normally rapidly repaired, and fetal deficiencies in several DNA repair proteins, including oxoguanine glycosylase 1 (OGG1) and breast cancer protein 1 (BRCA1), enhance the risk of drug-initiated postnatal neurodevelopmental deficits, and in some cases deficits in untreated progeny, the latter of which may be relevant to conditions like autism spectrum disorders (ASD). Risk is further regulated by fetal nuclear factor erythroid 2-related factor 2 (Nrf2), a ROS-sensing protein that upregulates an array of proteins, including antioxidative enzymes and DNA repair proteins. Imbalances between conceptal pathways for ROS formation, versus those for ROS detoxification and DNA repair, are important determinants of risk. Birth Defects Research (Part C) 108:108-130, 2016. © 2016 Wiley Periodicals, Inc.

Differences in neural crest sensitivity to ethanol account for the infrequency of anterior segment defects in the eye compared with craniofacial anomalies in a zebrafish model of fetal alcohol syndrome

BACKGROUND

Ethanol (ETOH) exposure during pregnancy is associated with craniofacial and neurologic abnormalities, but infrequently disrupts the anterior segment of the eye. In these studies, we used zebrafish to investigate differences in the teratogenic effect of ETOH on craniofacial, periocular, and ocular neural crest.

METHODS

Zebrafish eye and neural crest development was analyzed by means of live imaging, TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assay, immunostaining, detection of reactive oxygen species, and in situ hybridization.

RESULTS

Our studies demonstrated that foxd3-positive neural crest cells in the periocular mesenchyme and developing eye were less sensitive to ETOH than sox10-positive craniofacial neural crest cells that form the pharyngeal arches and jaw. ETOH increased apoptosis in the retina, but did not affect survival of periocular and ocular neural crest cells. ETOH also did not increase reactive oxygen species within the eye. In contrast, ETOH increased ventral neural crest apoptosis and reactive oxygen species production in the facial mesenchyme. In the eye and craniofacial region, sod2 showed high levels of expression in the anterior segment and in the setting of Sod2 knockdown, low levels of ETOH decreased migration of foxd3-positive neural crest cells into the developing eye. However, ETOH had minimal effect on the periocular and ocular expression of transcription factors (pitx2 and foxc1) that regulate anterior segment development.

CONCLUSION

Neural crest cells contributing to the anterior segment of the eye exhibit increased ability to withstand ETOH-induced oxidative stress and apoptosis. These studies explain the rarity of anterior segment dysgenesis despite the frequent craniofacial abnormalities in fetal alcohol syndrome. Birth Defects Research 109:1212-1227, 2017. © 2017 Wiley Periodicals, Inc.

17β-Estradiol via SIRT1/Acetyl-p53/NF-kB Signaling Pathway Rescued Postnatal Rat Brain Against Acute Ethanol Intoxication

Growing evidences reveal that 17β-estradiol has a wide variety of neuroprotective potential. Recently, it has been shown that 17β-estradiol can limit ethanol-induced neurotoxicity in neonatal rats. Whether it can stimulate SIRT1 signaling against ethanol intoxicity in developing brain remain elusive. Here, we report for the first time that 17β-estradiol activated SIRT1 to deacetylate p53 proteins against acute ethanol-induced oxidative stress, neuroinflammation, and neurodegeneration. A single subcutaneous injection of ethanol-induced oxidative stress triggered phospho c-jun N terminal kinase (p-JNK) and phospho mammalian target of rapamycin (p-mTOR) accompanied by neuroinflammation and widespread neurodegeneration. In contrast, 17β-estradiol cotreatment positively regulated SIRT1, inhibited p53 acetylation, reactive oxygen species (ROS) production, p-JNK, and p-mTOR activation and reduced neuroinflammation and neuronal cell death in the postnatal rat brain. Interestingly, SIRT1 inhibition with its inhibitor, i.e., EX527 further enhanced ethanol intoxication and also abolished the beneficial effects of 17β-estradiol against ethanol in the young rat's brain. Indeed, 17β-estradiol treatment increased the cell viability (HT22 cells), inhibited ROS production via the SIRT1/Acetyl-p53 pathway, and reduced the nuclear translocation of phospho-nuclear factor kappa B (p-NF-kB) in the BV2 microglia cells. Taken together, these results show that 17β-estradiol can be used as a potential neuroprotective agent against acute ethanol intoxication.

Neuronal survival in the brain: neuron type-specific mechanisms

Neurogenic regions of mammalian brain produce many more neurons that will eventually survive and reach a mature stage. Developmental cell death affects both embryonically produced immature neurons and those immature neurons that are generated in regions of adult neurogenesis. Removal of substantial numbers of neurons that are not yet completely integrated into the local circuits helps to ensure that maturation and homeostatic function of neuronal networks in the brain proceed correctly. External signals from brain microenvironment together with intrinsic signaling pathways determine whether a particular neuron will die. To accommodate this signaling, immature neurons in the brain express a number of transmembrane factors as well as intracellular signaling molecules that will regulate the cell survival/death decision, and many of these factors cease being expressed upon neuronal maturation. Furthermore, pro-survival factors and intracellular responses depend on the type of neuron and region of the brain. Thus, in addition to some common neuronal pro-survival signaling, different types of neurons possess a variety of 'neuron type-specific' pro-survival constituents that might help them to adapt for survival in a certain brain region. This review focuses on how immature neurons survive during normal and impaired brain development, both in the embryonic/neonatal brain and in brain regions associated with adult neurogenesis, and emphasizes neuron type-specific mechanisms that help to survive for various types of immature neurons. Importantly, we mainly focus on in vivo data to describe neuronal survival specifically in the brain, without extrapolating data obtained in the PNS or spinal cord, and thus emphasize the influence of the complex brain environment on neuronal survival during development.

Up-Regulation of PKR Signaling Pathway by Ethanol Displays an Age of Onset-Dependent Relationship

BACKGROUND

Ethanol (EtOH) neurotoxicity can result in devastating effects on brain and behavior by disrupting homeostatic signaling cascades and inducing cell death. One such mechanism involves double-stranded RNA activated protein kinase (PKR), a primary regulator of protein translation and cell viability in the presence of a virus or other external stimuli. EtOH-mediated up-regulation of interferon-gamma (IFN-γ; the oxidative stress-inducible regulator of PKR), PKR, and its target, p53, are still being fully elucidated.

METHODS

Using Western blot analysis, immunofluorescence, and linear regression analyses, changes in the IFN-γ-PKR-p53 pathway following chronic EtOH treatment in the frontal cortex of rodents were examined. The role of PKR on cell viability was also assessed in EtOH-treated cells using PKR overexpression vector and PKR inhibitor (PKRI).

RESULTS

In rats chronically fed EtOH, PKR, phosphorylated PKR (p-PKR), IFN-γ, and p53 were significantly increased following chronic EtOH exposure. Linear regression revealed a significant correlation between IFN-γ and p-PKR protein levels, as well as p-PKR expression and age of EtOH exposure. Overexpression of PKR resulted in greater cell death, while use of PKRI enhanced cell viability in EtOH-treated cells.

CONCLUSIONS

Chronic EtOH exposure activates the IFN-γ-PKR-p53 pathway in the frontal cortex of rodents. p-PKR expression is greater in brains of rodents exposed to EtOH at earlier ages compared to later life, suggesting a mechanism by which young brains could be more susceptible to EtOH-related brain injury. PKR and p-PKR were also colocalized in neurons and astrocytes of rats. This study provides additional insight into biochemical mechanisms underlying alcohol use disorder related neuropathology and warrants further investigation of PKR as a potential pharmacotherapeutic target to combat EtOH-related neurotoxicity, loss of protein translation and brain injury.

Chronic ethanol intake leads to structural and molecular alterations in the rat endometrium

We described the effects of low- and high-dose ethanol intake on the structure and apoptosis signaling of the uterine endometrium of UChA and UChB rats (animals with voluntary ethanol consumption). Thirty adult female rats, 90 days old, were divided into three groups (n = 10/group): UChA rats fed with 10% (v/v) ethanol ad libitum (free choice for water or ethanol) drinking < 1.9 g/kg/day; UChB rats fed with 10% (v/v) ethanol ad libitum (free choice for water or ethanol) drinking from 2 to 5 g/kg/day; control rats without ethanol (only water). After 120 days of treatment, rats displaying estrus were euthanized. Uterine epithelial cells of the UCh rats showed dilated cisterns of the rough endoplasmic reticulum, presence of lipid droplets, altered nuclear chromatin, and disrupted mitochondria. The UCh rats exhibited intense atrophied epithelial cells with smaller areas and perimeters of cytoplasm and nuclei. The endometrium of UChA rats showed higher levels of caspase-3 while Xiap and Bcl2 varied from moderate to weak. Both UChA and UChB rats exhibited a stronger immunoreaction to Ki-67 and IGFR-1 on epithelial and stromal cells. Chronic ethanol intake leads to structural and molecular alterations in the uterine endometrium of UCh rats, regardless of low- or high-dose consumption, promoting reproductive disorders.

Differential Contributions of Alcohol and the Nicotine-Derived Nitrosamine Ketone (NNK) to Insulin and Insulin-Like Growth Factor Resistance in the Adolescent Rat Brain

AIMS

Since epidemiologic studies suggest that tobacco smoke toxins, e.g. the nicotine-derived nitrosamine ketone (NNK) tobacco-specific nitrosamine, can be a co-factor in alcohol-related brain disease (ARBD), we examined the independent and additive effects of alcohol and NNK exposures on spatial learning/memory, and brain insulin/IGF signaling, neuronal function and oxidative stress.

METHODS

Adolescent Long Evans rats were fed liquid diets containing 0 or 26% caloric ethanol for 8 weeks. During weeks 3-8, rats were treated with i.p. NNK (2 mg/kg, 3×/week) or saline. In weeks 7-8, ethanol groups were binge-administered ethanol (2 g/kg; 3×/week). In week 8, at 12 weeks of age, rats were subjected to Morris Water Maze tests. Temporal lobes were used to assess molecular indices of insulin/IGF resistance, oxidative stress and neuronal function.

RESULTS

Ethanol and NNK impaired spatial learning, and NNK ± ethanol impaired memory. Linear trend analysis demonstrated worsening performance from control to ethanol, to NNK, and then ethanol + NNK. Ethanol ± NNK, caused brain atrophy, inhibited insulin signaling through the insulin receptor and Akt, activated GSK-3β, increased protein carbonyl and 3-nitrotyrosine, and reduced acetylcholinesterase. NNK increased NTyr. Ethanol + NNK had synergistic stimulatory effects on 8-iso-PGF-2α, inhibitory effects on p-p70S6K, tau and p-tau and trend effects on insulin-like growth factor type 1 (IGF-1) receptor expression and phosphorylation.

CONCLUSIONS

Ethanol, NNK and combined ethanol + NNK exposures that begin in adolescence impair spatial learning and memory in young adults. The ethanol and/or NNK exposures differentially impair insulin/IGF signaling through neuronal growth, survival and plasticity pathways, increase cellular injury and oxidative stress and reduce expression of critical proteins needed for neuronal function.

Rutin upregulates neurotrophic factors resulting in attenuation of ethanol-induced oxidative stress in HT22 hippocampal neuronal cells

BACKGROUND

Alcoholism, which refers to the excessive consumption of alcohol, has deleterious effects on personal and social health worldwide. Oxidative stress evoked by ethanol plays an important role in the pathogenesis of neurodegenerative diseases. Rutin is a bioflavonoid that has been demonstrated to scavenge superoxide radicals. However, the effects of rutin on neuronal toxicity following ethanol-induced oxidative stress have not previously been investigated. Thus we investigated the antioxidant effect of rutin in hippocampal neuronal cells (HT22 cells) exposed to ethanol.

RESULTS

We found that rutin pretreatment prevented the ethanol-induced decrease in protein level expression of nerve growth factor, glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) in HT22 cells. Cell viability as analyzed by the MTT method revealed a significant increase in cell viability in the rutin-treated group compared with the ethanol-only treated group. Antioxidant effect of rutin was confirmed to be due to reduction of intracellular reactive oxidative species production in ethanol-treated HT22 cells. Moreover, rutin significantly increased the level of the antioxidant glutathione, and the activities of the antioxidant enzymes superoxide dismutase and catalase.

CONCLUSION

These findings indicate that rutin has potential as a therapeutic agent to treat alcohol-related neurodegenerative disorders.

Chronic Alcohol Exposure Decreases 53BP1 Protein Levels Leading to a Defective DNA Repair in Cultured Primary Cortical Neurons

Chronic alcohol consumption may cause neurodevelopmental and neurodegenerative disorders. Alcohol neurotoxicity is associated with the production of acetaldehyde and reactive oxygen species that induce oxidative DNA damage. However, the molecular mechanisms by which ethanol disturbs the DNA damage response (DDR), resulting in a defective DNA repair, remain unknown. Here, we have used cultured primary cortical neurons exposed to 50 or 100 mM ethanol for 7 days to analyze the ethanol-induced DDR. Ethanol exposure produced a dose-dependent generation of double strand breaks and the formation of DNA damage foci immunoreactive for the histone γH2AX, a DNA damage marker, and for the ubiquitylated H2A, which is involved in chromatin remodeling at DNA damage sites. Importantly, these DNA damage foci failed to recruit the protein 53BP1, a crucial DNA repair factor. This effect was associated with a drop in 53BP1 mRNA and protein levels and with an inhibition of global transcription. Moreover, ethanol-exposed neurons treated with ionizing radiation (2 Gy) also failed to recruit 53BP1 at DNA damage foci and exhibited a greater vulnerability to DNA lesions than irradiated control neurons. Our results support that defective DNA repair, mediated by the deficient expression and recruitment of 53BP1 to DNA damage sites, represents a novel mechanism involved in ethanol neurotoxicity. The design of therapeutic strategies that increase or stabilize 53BP1 levels might potentially promote DNA repair and partially compensate alcohol neurotoxicity.

Ethanol intake-induced apoptosis in glial cells and axonal disorders in the cerebellar white matter of UChA rats (voluntary ethanol consumers)

Ethanol intake may cause alterations in cellular metabolism altering motricity, learning and cognition. The cerebellum is one of the most susceptible organs to ethanol-related disorders during development, and is associated with oxidative stress-induced apoptosis being crucial for pathogenic consequences. The UChA variety is a special strain of Wistar rat genetically selected and represents a rare model for the studies related to genetic, biochemical, physiological, nutritional, and pharmacological effects of ethanol. We evaluated the structure and apoptosis in the cerebellar white matter of UChA rats. There were two groups of 09 rats: a control group that did not consume ethanol, and an experimental group of UChA rats that consumed ethanol at 10% (v/v) (<2 g ethanol/kg body weight/day). At 120 days old, rats were anaesthetized followed by decapitation, and their cerebella were collected and fixed. Cerebellar sections were subjected to immunohistochemistry for Caspase-3 and XIAP and transmission electron microscopy (TEM). The UChA group showed more glial cells immunoreactive for caspase-3 and less for XIAP than control group. Alcohol consumption affected myelin integrity. Severe ultrastructural damages in UChA group were observed such as disruption of the myelin sheath, disorganization and deformation of its components, and an increase in the interaxonal spaces. In conclusion, our data demonstrated that ethanol induced apoptosis in the glial cells and promoted an intense change in the myelin sheath of UChA rats, which may cause functional disorders.

Pre- and postnatal exposure to moderate levels of ethanol can have long-lasting effects on hippocampal glutamate uptake in adolescent offspring

The developing brain is vulnerable to the effects of ethanol. Glutamate is the main mediator of excitatory signals in the brain and is probably involved in most aspects of normal brain function during development. The aim of this study was to investigate vulnerability to and the impact of ethanol toxicity on glutamate uptake signaling in adolescent rats after moderate pre and postnatal ethanol exposure. Pregnant female rats were divided into three groups and treated only with water (control), non-alcoholic beer (vehicle) or 10% (v/v) beer solution (moderate prenatal alcohol exposure—MPAE). Thirty days after birth, adolescent male offspring were submitted to hippocampal acute slice procedure. We assayed glutamate uptake and measured glutathione content and also quantified glial glutamate transporters (EAAT 1 and EAAT 2). The glutamate system vulnerability was tested with different acute ethanol doses in naïve rats and compared with the MPAE group. We also performed a (lipopolysaccharide-challenge (LPS-challenge) with all groups to test the glutamate uptake response after an insult. The MPAE group presented a decrease in glutamate uptake corroborating a decrease in glutathione (GSH) content. The reduction in GSH content suggests oxidative damage after acute ethanol exposure. The glial glutamate transporters were also altered after prenatal ethanol treatment, suggesting a disturbance in glutamate signaling. This study indicates that impairment of glutamate uptake can be dose-dependent and the glutamate system has a higher vulnerability to ethanol toxicity after moderate ethanol exposure In utero. The effects of pre- and postnatal ethanol exposure can have long-lasting impacts on the glutamate system in adolescence and potentially into adulthood.

Activation of mitochondrial function and Hb expression in non-haematopoietic cells by an EPO inducer ameliorates ischaemic diseases in mice

BACKGROUND AND PURPOSE

Many organs suffer from ischaemic injuries that reduce their ability to generate sufficient energy, which is required for functional maintenance and repair. Erythropoietin (EPO) ameliorates ischaemic injuries by pleiotropic effects. The aim of this study was to investigate the effect and mechanism of a small molecule EH-201, and found it as a potent EPO inducer and its effect in non-haematopoietic cells for therapeutic potential in ischemic disorders.

EXPERIMENTAL APPROACH

Mice kidney slices, primary hepatocytes, primary cardiomyocytes and C2C12 myoblasts were treated with EH-201. The effects of this treatment on EPO, Hb expression and mitochondrial biogenesis were analysed. In vivo, doxorubicin-induced cardiomyopathic mice were treated with EH-201. The mice were subjected to an endurance test, electrocardiography and echocardiography, and a histological examination of the isolated hearts was performed. EH-201 was also administered to cisplatin-induced nephropathic mice.

KEY RESULTS

In non-haematopoietic cells, EH-201 was potent at inducing EPO. EH-201 also stimulated mitochondrial biogenesis and enhanced the expression of Hb by a mechanism dependent on EPO-mediated signalling. In mechanistic studies, using EPO and EPO receptor-neutralizing antibodies, we confirmed that EH-201 enhances EPO-EPOR autocrine activity. EH-201 robustly increased the endurance performance activity of healthy and cardiomyopathic mice during hypoxic stress, enhanced myocardial mitochondrial biogenesis and Hb expression, and also improved cardiac function. EH-201 ameliorated anaemia and renal dysfunction in nephropathic mice.

CONCLUSIONS AND IMPLICATIONS

The enhancement and recovery of cellular functions through the stimulation of mitochondrial activity and Hb production in non-haematopoietic cells by an inducer of endogenous EPO has potential as a therapeutic strategy for ischaemic diseases.

Advances in the development of novel antioxidant therapies as an approach for fetal alcohol syndrome prevention

Ethanol is the most common human teratogen, and its consumption during pregnancy can produce a wide range of abnormalities in infants known as fetal alcohol spectrum disorder (FASD). The major characteristics of FASD can be divided into: (i) growth retardation, (ii) craniofacial abnormalities, and (iii) central nervous system (CNS) dysfunction. FASD is the most common cause of nongenetic mental retardation in Western countries. Although the underlying molecular mechanisms of ethanol neurotoxicity are not completely determined, the induction of oxidative stress is believed to be one central process linked to the development of the disease. Currently, there is no known effective strategy for prevention (other than alcohol avoidance) or treatment. In the present review we will provide the state of art in the evidence for the use of antioxidants as a potential therapeutic strategy for the treatment using whole-embryo and culture cells models of FASD. We conclude that the imbalance of the intracellular redox state contributes to the pathogenesis observed in FASD models, and we suggest that antioxidant therapy can be considered a new efficient strategy to mitigate the effects of prenatal ethanol exposure.

Differentially co-expressed genes in postmortem prefrontal cortex of individuals with alcohol use disorders: influence on alcohol metabolism-related pathways

Chronic alcohol consumption may induce gene expression alterations in brain reward regions such as the prefrontal cortex (PFC), modulating the risk of alcohol use disorders (AUDs). Transcriptome profiles of 23 AUD cases and 23 matched controls (16 pairs of males and 7 pairs of females) in postmortem PFC were generated using Illumina's HumanHT-12 v4 Expression BeadChip. Probe-level differentially expressed genes and gene modules in AUD subjects were identified using multiple linear regression and weighted gene co-expression network analyses. The enrichment of differentially co-expressed genes in alcohol dependence-associated genes identified by genome-wide association studies (GWAS) was examined using gene set enrichment analysis. Biological pathways overrepresented by differentially co-expressed genes were uncovered using DAVID bioinformatics resources. Three AUD-associated gene modules in males [Module 1 (561 probes mapping to 505 genes): r = 0.42, P(correlation) = 0.020; Module 2 (815 probes mapping to 713 genes): r = 0.41, P(correlation) = 0.020; Module 3 (1,446 probes mapping to 1,305 genes): r = -0.38, P(correlation) = 0.030] and one AUD-associated gene module in females [Module 4 (683 probes mapping to 652 genes): r = 0.64, P(correlation) = 0.010] were identified. Differentially expressed genes mapped by significant expression probes (P(nominal) ≤ 0.05) clustered in Modules 1 and 2 were enriched in GWAS-identified alcohol dependence-associated genes [Module 1 (134 genes): P = 0.028; Module 2 (243 genes): P = 0.004]. These differentially expressed genes, including ALDH2, ALDH7A1, and ALDH9A1, are involved in cellular functions such as aldehyde detoxification, mitochondrial function, and fatty acid metabolism. Our study revealed differentially co-expressed genes in postmortem PFC of AUD subjects and demonstrated that some of these differentially co-expressed genes participate in alcohol metabolism.

The role of NADPH oxidase in a mouse model of fetal alcohol syndrome

OBJECTIVE

Fetal alcohol syndrome (FAS) is the most common cause of nongenetic mental retardation. Oxidative stress is one of the purported mechanisms. Nicotinamide adenine dinucleotide phosphate oxidase (NOX) is an enzyme involved in the production of reactive oxygen species. Our objective was to evaluate NOX in the fetal brain of a well-validated mouse model of FAS.

STUDY DESIGN

Timed, pregnant C57BL/6J mice were injected intraperitoneally with 0.03 mL/g of either 25% ethyl alcohol or saline. Fetal brain, liver, and placenta were harvested on gestational day 18. The unit of analysis was the litter; tissue from 6-8 litters in the alcohol and control group was isolated. Evaluation of messenger ribonucleic acid (mRNA) expression of NOX subunits (DUOX1, DUOX2, NOX1, NOX2, NOX3, NOX4, NOXA1, NOXO1, RAC1, p22phox, and p67phox) was performed using quantitative real-time polymerase chain reaction; alcohol vs placebo groups were compared using a Student t test or a Mann-Whitney test (P < .05).

RESULTS

Alcohol exposed fetal brains showed significant up-regulation in subunits DUOX2 (1.61 ± 0.28 vs 0.84 ± 0.09; P = .03), NOXA1 (1.75 ± 0.27 vs 1.09 ± 0.06; P = .04), and NOXO1 (1.59 ± 0.10 vs 1.28 ± 0.05; P = .02). Differences in mRNA expression in the placenta were not significant; p67phox was significantly up-regulated in alcohol-exposed livers.

CONCLUSION

Various NOX subunits are up-regulated in fetal brains exposed to alcohol. This effect was not observed in the fetal liver or placenta. Given the available evidence, the NOX system may be involved in the causation of FAS through the generation of reactive oxygen species and may be a potential target for preventative treatment in FAS.

Differential effects of p53 on bystander phenotypes induced by gamma ray and high LET heavy ion radiation

High LET particle irradiation has several potential advantages over γ-rays such as p53-independent response. The purpose of this work is to disclose the effect of p53 on the bystander effect induced by different LET irradiations and underlying mechanism. Lymphocyte cells of TK6 (wild type p53) and HMy2.CIR (mutated p53) were exposed to either low or high LET irradiation, then their mitochondrial dysfunction and ROS generation were detected. The micronuclei (MN) induction in HL-7702 hepatocytes co-cultured with irradiated lymphocytes was also measured. It was found that the mitochondrial dysfunction, p66(Shc) activation, and intracellular ROS were enhanced in TK6 but not in HMy2.CIR cells after γ-ray irradiation, but all of them were increased in both cell lines after carbon and iron irradiation. Consistently, the bystander effect of MN formation in HL-7702 cells was only triggered by γ-irradiated TK6 cells but not by γ-irradiated HMy2.CIR cells. But this bystander effect was induced by both lymphocyte cell lines after heavy ion irradiation. PFT-μ, an inhibitor of p53, only partly inhibited ROS generation and bystander effect induced by 30 keV/μm carbon-irradiated TK6 cells but failed to suppress the bystander effect induced by the TK6 cells irradiated with either 70 keV/μm carbon or 180 keV/μm iron. The mitochondrial inhibitors of rotenone and oligomycin eliminated heavy ion induced ROS generation in TK6 and HMy2.CIR cells and hence diminished the bystander effect on HL-7702 cells. These results clearly demonstrate that the bystander effect is p53-dependent for low LET irradiation, but it is p53-independent for high LET irradiation which may be because of p53-independent ROS generation due to mitochondrial dysfunction.

Neuroprotective profile of pyruvate against ethanol-induced neurodegeneration in developing mice brain

Exposure to ethanol during developmental stages leads to several types of neurological disorders. Apoptotic neurodegeneration due to ethanol exposure is a main feature in alcoholism. Exposure of developing animals to alcohol induces apoptotic neuronal death and causes fetal alcohol syndrome. In the present study, we observed the possible protective effect of pyruvate against ethanol-induced neurodegeneration. Exposure of developing mice to ethanol (2.5 g/kg) induces apoptotic neurodegeneration and widespread neuronal cell death in the cortex and thalamus. Co-treatment of pyruvate (500 mg/kg) protects neuronal cell against ethanol by the reduced expression of caspase-3 in these brain regions. Immunohistochemical analysis and TUNNEL at 24 h showed that apoptotic cell death induced by ethanol in the cortex and thalamus is reduced by pyruvate. Histomorphological analysis at 24 h with cresyl violet staining also proved that pyruvate reduced the number of neuronal cell loss in the cortex and thalamus. The results showed that ethanol increased the expression of caspase-3 and thus induced apoptotic neurodegeneration in the developing mice cortex and thalamus, while co-treatment of pyruvate inhibits the induction of caspase-3 and reduced the cell death in these brain regions. These findings, therefore, showed that treatment of pyruvate inhibits ethanol-induced neuronal cell loss in the postnatal seven (P7) developing mice brain and may appear as a safe neuroprotectant for treating neurodegenerative disorders in newborns and infants.

Infrared microspectroscopy identifies biomolecular changes associated with chronic oxidative stress in mammary epithelium and stroma of breast tissues from healthy young women: implications for latent stages of breast carcinogenesis

Studies of the decades-long latent stages of breast carcinogenesis have been limited to when hyperplastic lesions are already present. Investigations of earlier stages of breast cancer (BC) latency have been stymied by the lack of fiducial biomarkers needed to identify where in histologically normal tissues progression toward a BC might be taking place. Recent evidence suggests that a marker of chronic oxidative stress (OxS), protein adducts of 4-hydroxy-2-nonenal (4HNE), can meet this need. Specifically: (1) 4HNE immunopositive (4HNE+) mammary epithelial (ME) cells were found to be prevalent in normal (reduction mammoplasty) tissues of most women (including many teenagers) studied, representative of those living in the United States' high risk-posing environment and: (2) marked (> 1.5-fold) differences were identified between tissues of healthy young women with many vs. few 4HNE+ ME cells in the relative levels of transcripts for 42 of the 84 OxS-associated genes represented in SABioscience Oxidative-Stress/Oxidative-Defense PCR array. Herein we used synchrotron radiation-based Fourier-transform infrared (SR-FTIR) microspectroscopy to identify molecular changes associated with 4HNE adducts in basal and luminal ME cells in terminal ductal units (TDLU), which are the cells of origin of BC, and associated intralobular and interlobular stroma, known contributors to carcinogenesis. Multivariate analysis-derived wavenumbers differentiated 4HNE+ and 4HNE- cells in each of the anatomical compartments. Specifically, principal component and linear discriminant analyses of mid-infrared spectra obtained from these cells revealed unambiguous, statistically highly significant differences in the "biochemical fingerprint" of 4HNE+ vs. 4HNE- luminal and basal ME cells, as well as between associated intralobular and interlobular stroma. These findings demonstrate further SR-FTIR microspectroscopy's ability to identify molecular changes associated with altered physiological and/or pathophysiological states, in this case with a state of chronic OxS that provides a pro-carcinogenic microenvironment.

Mitochondria-targeted heme oxygenase-1 induces oxidative stress and mitochondrial dysfunction in macrophages, kidney fibroblasts and in chronic alcohol hepatotoxicity

The inducible form of Heme Oxygenase-1 (HO-1), a major endoplasmic reticulum (ER) associated heme protein, is known to play important roles in protection against oxidative and chemical stress by degrading free heme released from degradation of heme proteins. In this study we show that induced expression of HO-1 by subjecting macrophage RAW-264.7 cells to chemical or physiological hypoxia resulted in significant translocation of HO-1 protein to mitochondria. Transient transfection of COS-7 cells with cloned cDNA also resulted in mitochondrial translocation of HO-1. Deletion of N-terminal ER targeting domain increased mitochondrial translocation under the transient transfection conditions. Mitochondrial localization of both intact HO-1 and N-terminal truncated HO-1 caused loss of heme aa-3 and cytochrome c oxidase (CcO) activity in COS-7 cells. The truncated protein, which localizes to mitochondria at higher levels, induced substantially steeper loss of CcO activity and reduced heme aa3 content. Furthermore, cells expressing mitochondria targeted HO-1 also induced higher ROS production. Consistent with dysfunctional state of mitochondria induced by HO-1, the mitochondrial recruitment of autophagy markers LC-3 and Drp-1 was also increased in these cells. Chronic ethanol feeding in rats also caused an increase in mitochondrial HO-1 and decrease in CcO activity. These results show that as opposed to the protective effect of the ER associated HO-1, mitochondria targeted HO-1 under normoxic conditions induces mitochondrial dysfunction.

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Under hypoxia, the inducible Heme Oxygenase-1 (HO-1) is localized in mitochondria.

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N-terminal truncated HO-1 is more efficiently translocated to mitochondria.

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Mitochondria targeted HO-1 induces oxidative stress and CcO dysfunction.

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Mitochondrial HO-1 content is increased in alcohol treated rat livers.