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Fish EW, Mendoza-Romero HN, Love CA, Dragicevich CJ, Cannizzo MD, Boschen KE, Hepperla A, Simon JM, Parnell SE. The pro-apoptotic Bax gene modifies susceptibility to craniofacial dysmorphology following gastrulation-stage alcohol exposure. Birth Defects Res 2022; 114:1229-1243. [PMID: 35396933 PMCID: PMC10103739 DOI: 10.1002/bdr2.2009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 03/11/2022] [Accepted: 03/23/2022] [Indexed: 11/07/2022]
Abstract
BACKGROUND During early development, alcohol exposure causes apoptotic cell death in discrete regions of the embryo which are associated with distinctive patterns of later-life abnormalities. In gastrulation, which occurs during the third week of human pregnancy, alcohol targets the ectoderm, the precursor of the eyes, face, and brain. This midline tissue loss leads to the craniofacial dysmorphologies, such as microphthalmia and a smooth philtrum, which define fetal alcohol syndrome (FAS). An important regulator of alcohol-induced cell death is the pro-apoptotic protein Bax. The current study determines if mice lacking the Bax gene are less susceptible to the pathogenic effects of gastrulation-stage alcohol exposure. METHODS Male and female Bax+/- mice mated to produce embryos with full (-/- ) or partial (+/- ) Bax deletions, or Bax+/+ wild-type controls. On Gestational Day 7 (GD 7), embryos received two alcohol (2.9 g/kg, 4 hr apart), or control exposures. A subset of embryos was collected 12 hr later and examined for the presence of apoptotic cell death, while others were examined on GD 17 for the presence of FAS-like facial features. RESULTS Full Bax deletion reduced embryonic apoptotic cell death and the incidence of fetal eye and face malformations, indicating that Bax normally facilitates the development of alcohol-induced defects. An RNA-seq analysis of GD 7 Bax+/+ and Bax-/- embryos revealed 63 differentially expressed genes, some of which may interact with the Bax deletion to further protect against apoptosis. CONCLUSIONS Overall, these experiments identify that Bax is a primary teratogenic mechanism of gastrulation-stage alcohol exposure.
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Affiliation(s)
- Eric W Fish
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Haley N Mendoza-Romero
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Charlotte A Love
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Constance J Dragicevich
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Michael D Cannizzo
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Karen E Boschen
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Austin Hepperla
- Carolina Institute for Developmental Disabilities, University of North Carolina, Chapel Hill, North Carolina, USA.,Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Jeremy M Simon
- Carolina Institute for Developmental Disabilities, University of North Carolina, Chapel Hill, North Carolina, USA.,Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina, USA.,Department of Genetics, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Scott E Parnell
- Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, North Carolina, USA.,Carolina Institute for Developmental Disabilities, University of North Carolina, Chapel Hill, North Carolina, USA.,Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina, USA
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Todd D, Clapp M, Dains P, Karacay B, Bonthius DJ. Purkinje cell-specific deletion of CREB worsens alcohol-induced cerebellar neuronal losses and motor deficits. Alcohol 2022; 101:27-35. [PMID: 35378204 PMCID: PMC9783827 DOI: 10.1016/j.alcohol.2022.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 02/24/2022] [Accepted: 02/24/2022] [Indexed: 12/27/2022]
Abstract
INTRODUCTION Exposure to alcohol during pregnancy can kill developing fetal neurons and lead to fetal alcohol spectrum disorder (FASD) in the offspring. However, not all fetuses are equally vulnerable to alcohol toxicity. These differences in vulnerability among individuals are likely due, at least in part, to genetic differences. Some genes encode neuroprotective molecules that act through signaling pathways to protect neurons against alcohol's toxic effects. One signaling pathway that can protect cultured neurons against alcohol-induced cell death in vitro is the cAMP pathway. A goal of this study was to determine whether the cAMP pathway can exert a similar neuroprotective effect against alcohol in vivo. A key molecule within the cAMP pathway is cAMP response element binding protein (CREB). In this study, CREB was specifically disrupted in cerebellar Purkinje cells to study its role in protection of cerebellar neurons against alcohol toxicity. METHODS Mice with Purkinje cell-specific knockout of CREB were generated with the Cre-lox system. A 2 × 2 design was used in which Cre-negative and Cre-positive mice received either 0.0 or 2.2 mg/g ethanol by intraperitoneal (i.p.) injection daily over postnatal day (PD) 4-9. Stereological cell counts of cerebellar Purkinje cells and granule cells were performed on PD 10. Motor function was assessed on PD 40 using the rotarod. RESULTS Purkinje cell-specific disruption of CREB alone (in the absence of alcohol) induced only a small reduction in Purkinje cell number. However, the loss of CREB function from Purkinje cells greatly increased the vulnerability of Purkinje cells to alcohol-induced cell death. While alcohol killed 20% of Purkinje cells in the Cre-negative (CREB-expressing) mice, alcohol killed 57% of Purkinje cells in the Cre-positive (CREB-nonexpressing) mice. This large loss of Purkinje cells did not lead to similar alcohol-induced losses of granule cells. In the absence of alcohol, lack of CREB function in Purkinje cells had no effect on rotarod performance. However, in the presence of alcohol, disruption of CREB in Purkinje cells substantially worsened rotarod performance. DISCUSSION Disruption of a single gene (CREB) in a single neuronal population (Purkinje cells) greatly increases the vulnerability of that cell population to alcohol-induced cell death and worsens alcohol-induced brain dysfunction. The results suggest that the cAMP pathway can protect cells in vivo against alcohol toxicity and underline the importance of genetics in determining the neuropathology and behavioral deficits of FASD.
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Affiliation(s)
- Dylan Todd
- Neuroscience Program, University of Iowa Carver College of Medicine, Iowa City, IA
| | - Michael Clapp
- Department of Pediatrics, University of Iowa, Carver College of Medicine, Iowa City, IA
| | - Parker Dains
- Department of Pediatrics, University of Iowa, Carver College of Medicine, Iowa City, IA
| | - Bahri Karacay
- Department of Pediatrics, University of Iowa, Carver College of Medicine, Iowa City, IA
| | - Daniel J. Bonthius
- Neuroscience Program, University of Iowa Carver College of Medicine, Iowa City, IA,Department of Pediatrics, University of Iowa, Carver College of Medicine, Iowa City, IA,Atrium Health/Levine Children’s Hospital, Charlotte, NC
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Li W, Li Z, Zhou D, Zhang X, Yan J, Huang G. Maternal folic acid deficiency stimulates neural cell apoptosis via miR-34a associated with Bcl-2 in the rat foetal brain. Int J Dev Neurosci 2018; 72:6-12. [PMID: 30447272 DOI: 10.1016/j.ijdevneu.2018.11.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 09/21/2018] [Accepted: 11/12/2018] [Indexed: 01/10/2023] Open
Abstract
Embryonic development is a critical period wherein brain neurons are generated and organized. Maternal dietary folate, a cofactor in one-carbon metabolism, modulates neurogenesis and apoptosis in foetal brain neurons. We hypothesized that aberrant neuronal apoptosis may affect the development of the central nervous system during maternal folic acid deficiency, with evident effects because maternal folic acid deficiency modulates the microRNA-34a associated with Bcl-2 pathway during embryonic development. Four-week-old female Sprague-Dawley rats were divided randomly into two groups (10 rats per group): a folate-deficient diet group and a folate-normal diet group. The diets were administered to the rats 60 d before mating, which was continued for the pregnant dams until parturition. Maternal folic acid deficiency increased neuronal apoptosis in the hippocampus and the cortex in the offspring. Furthermore, maternal folic acid deficiency increased the ratio of cleaved caspase-3/caspase-3, followed by an increase in caspase-3 activity. Moreover, maternal folic acid deficiency downregulated Bcl-2 and upregulated Bax, and this effect associate with maternal folic acid deficient increases expression of microRNA-34a. Together, the present results indicate that maternal folic acid deficiency stimulates neuronal apoptosis via microRNA-34a associated with Bcl-2 signalling in rat offspring.
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Affiliation(s)
- Wen Li
- Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, Tianjin, 300070, China
| | - Zhenshu Li
- Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, Tianjin, 300070, China
| | - Dezheng Zhou
- Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, Tianjin, 300070, China
| | - Xumei Zhang
- Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, Tianjin, 300070, China
| | - Jing Yan
- Department of Social Medicine and Health Administration, School of Public Health, Tianjin Medical University, Tianjin, 300070, China
| | - Guowei Huang
- Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, Tianjin, 300070, China.
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Todd D, Bonthius DJ, Sabalo LM, Roghair J, Karacay B, Bousquet SL, Bonthius DJ. Regional Patterns of Alcohol-Induced Neuronal Loss Depend on Genetics: Implications for Fetal Alcohol Spectrum Disorder. Alcohol Clin Exp Res 2018; 42:1627-1639. [PMID: 29957842 DOI: 10.1111/acer.13824] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 05/11/2018] [Accepted: 06/06/2018] [Indexed: 12/23/2022]
Abstract
BACKGROUND Alcohol exposure during pregnancy can kill developing neurons and lead to fetal alcohol spectrum disorder (FASD). However, affected individuals differ in their regional patterns of alcohol-induced neuropathology. Because neuroprotective genes are expressed in spatially selective ways, their mutation could increase the vulnerability of some brain regions, but not others, to alcohol teratogenicity. The objective of this study was to determine whether a null mutation of neuronal nitric oxide synthase (nNOS) can increase the vulnerability of some brain regions, but not others, to alcohol-induced neuronal losses. METHODS Immunohistochemistry identified brain regions in which nNOS is present or absent throughout postnatal development. Mice genetically deficient for nNOS (nNOS-/- ) and wild-type controls received alcohol (0.0, 2.2, or 4.4 mg/g/d) over postnatal days (PD) 4 to 9. Mice were sacrificed in adulthood (~PD 115), and surviving neurons in the olfactory bulb granular layer and brain stem facial nucleus were quantified stereologically. RESULTS nNOS was expressed throughout postnatal development in olfactory bulb granule cells but was never expressed in the facial nucleus. In wild-type mice, alcohol reduced neuronal survival to similar degrees in both cell populations. However, null mutation of nNOS more than doubled alcohol-induced cell death in the olfactory bulb granule cells, while the mutation had no effect on the facial nucleus neurons. As a result, in nNOS-/- mice, alcohol caused substantially more cell loss in the olfactory bulb than in the facial nucleus. CONCLUSIONS Mutation of the nNOS gene substantially increases vulnerability to alcohol-induced cell loss in a brain region where the gene is expressed (olfactory bulb), but not in a separate brain region, where the gene is not expressed (facial nucleus). Thus, differences in genotype may explain why some individuals are vulnerable to FASD, while others are not, and may determine the specific patterns of neuropathology in children with FASD.
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Affiliation(s)
- Dylan Todd
- Neuroscience Program , Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | | | - Lia Marie Sabalo
- Department of Pediatrics , Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Jasmine Roghair
- Department of Pediatrics , Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Bahri Karacay
- Department of Pediatrics , Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | | | - Daniel J Bonthius
- Neuroscience Program , Carver College of Medicine, University of Iowa, Iowa City, Iowa.,Department of Pediatrics , Carver College of Medicine, University of Iowa, Iowa City, Iowa.,Department of Neurology , Carver College of Medicine, University of Iowa, Iowa City, Iowa
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5
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Cholinergic System and Oxidative Stress Changes in the Brain of a Zebrafish Model Chronically Exposed to Ethanol. Neurotox Res 2017; 33:749-758. [DOI: 10.1007/s12640-017-9816-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 08/17/2017] [Accepted: 09/05/2017] [Indexed: 01/09/2023]
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6
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Bâ A. Alcohol and thiamine deficiency trigger differential mitochondrial transition pore opening mediating cellular death. Apoptosis 2017; 22:741-752. [DOI: 10.1007/s10495-017-1372-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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7
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Saito M, Chakraborty G, Hui M, Masiello K, Saito M. Ethanol-Induced Neurodegeneration and Glial Activation in the Developing Brain. Brain Sci 2016; 6:brainsci6030031. [PMID: 27537918 PMCID: PMC5039460 DOI: 10.3390/brainsci6030031] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 08/05/2016] [Accepted: 08/12/2016] [Indexed: 11/16/2022] Open
Abstract
Ethanol induces neurodegeneration in the developing brain, which may partially explain the long-lasting adverse effects of prenatal ethanol exposure in fetal alcohol spectrum disorders (FASD). While animal models of FASD show that ethanol-induced neurodegeneration is associated with glial activation, the relationship between glial activation and neurodegeneration has not been clarified. This review focuses on the roles of activated microglia and astrocytes in neurodegeneration triggered by ethanol in rodents during the early postnatal period (equivalent to the third trimester of human pregnancy). Previous literature indicates that acute binge-like ethanol exposure in postnatal day 7 (P7) mice induces apoptotic neurodegeneration, transient activation of microglia resulting in phagocytosis of degenerating neurons, and a prolonged increase in glial fibrillary acidic protein-positive astrocytes. In our present study, systemic administration of a moderate dose of lipopolysaccharides, which causes glial activation, attenuates ethanol-induced neurodegeneration. These studies suggest that activation of microglia and astrocytes by acute ethanol in the neonatal brain may provide neuroprotection. However, repeated or chronic ethanol can induce significant proinflammatory glial reaction and neurotoxicity. Further studies are necessary to elucidate whether acute or sustained glial activation caused by ethanol exposure in the developing brain can affect long-lasting cellular and behavioral abnormalities observed in the adult brain.
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Affiliation(s)
- Mariko Saito
- Division of Neurochemisty, Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA.
- Department of Psychiatry, New York University Langone Medical Center, 550 First Avenue, New York, NY 10016, USA.
| | - Goutam Chakraborty
- Division of Neurochemisty, Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA.
| | - Maria Hui
- Division of Neurochemisty, Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA.
| | - Kurt Masiello
- Division of Neurochemisty, Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA.
| | - Mitsuo Saito
- Department of Psychiatry, New York University Langone Medical Center, 550 First Avenue, New York, NY 10016, USA.
- Division of Analytical Psychopharmacology, Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA.
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8
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Heaton MB, Paiva M, Kubovec S. Differential effects of ethanol on bid, tBid, and Bax:tBid interactions in postnatal day 4 and postnatal day 7 rat cerebellum. Alcohol Clin Exp Res 2016; 39:55-63. [PMID: 25623406 DOI: 10.1111/acer.12603] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 10/13/2014] [Indexed: 12/27/2022]
Abstract
BACKGROUND Exposure to ethanol (EtOH) during central nervous system (CNS) development can lead to a wide array of neuroanatomical, behavioral, and cognitive abnormalities, broadly subsumed under the fetal alcohol spectrum disorder classification. One mode of EtOH-induced interference in the normal developmental program appears to be through induction of apoptotic processes mediated by the Bcl-2 family of survival-regulatory proteins. The present series of studies investigated the role of the Bcl-2-related, pro-apoptotic Bid protein, and its truncated, apoptotically active fragment, tBid, in developmental EtOH neurotoxicity. METHODS Protein analyses were made via enzyme-linked immunosorbent assays (ELISA) in neonatal rat cerebellum, of basal Bid, and of Bid and tBid, following EtOH exposure via vapor inhalation, at an age of peak EtOH sensitivity in this region (postnatal day 4 [P4]) and a later age of relative resistance (P7). ELISA analyses were also made of Bax:tBid heterodimers, a process which activates Bax, essential for its apoptotic functioning. Finally, in vitro assessments of the importance of tBid to EtOH neurotoxicity were made in cultured cerebellar granule cells, using a specific tBid inhibitor. RESULTS Basal levels of Bid were higher at P4 compared to P7, possibly contributing to the differential sensitivity. EtOH exposure elicited further increases in cytosolic Bid and mitochondrial tBid when administration was at P4, but not at P7. Bax:tBid heterodimers were markedly increased by EtOH exposure on P4, an increase which persisted even 2 hours after termination of treatment. Similar effects were not seen at P7. The in vitro analyses revealed that tBid inhibition provided complete protection against EtOH-induced cell death and depressed EtOH-mediated cytochrome-c release. CONCLUSIONS These results suggest that Bid/tBid may be important elements in EtOH-mediated neurotoxicity during CNS development. The molecular processes and interactions revealed may represent critical points which can be targeted in studies concerned with designing possible therapeutic strategies for minimizing these devastative effects.
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Affiliation(s)
- Marieta B Heaton
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, Florida; McKnight Brain Institute, Gainesville, Florida; Center for Addiction Research and Education, Gainesville, Florida
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Abstract
Cerebellar disorders trigger the symptoms of movement problems, imbalance, incoordination, and frequent fall. Cerebellar disorders are shown in various CNS illnesses including a drinking disorder called alcoholism. Alcoholism is manifested as an inability to control drinking in spite of adverse consequences. Human and animal studies have shown that cerebellar symptoms persist even after complete abstinence from drinking. In particular, the abrupt termination (ethanol withdrawal) of long-term excessive ethanol consumption has shown to provoke a variety of neuronal and mitochondrial damage to the cerebellum. Upon ethanol withdrawal, excitatory neurotransmitter molecules such as glutamate are overly released in brain areas including cerebellum. This is particularly relevant to the cerebellar neuronal network as glutamate signals are projected to Purkinje neurons through granular cells that are the most populated neuronal type in CNS. This excitatory neuronal signal may be elevated by ethanol withdrawal stress, which promotes an increase in intracellular Ca(2+) level and a decrease in a Ca(2+)-binding protein, both of which result in the excessive entry of Ca(2+) to the mitochondria. Subsequently, mitochondria undergo a prolonged opening of mitochondrial permeability transition pore and the overproduction of harmful free radicals, impeding adenosine triphosphate (ATP)-generating function. This in turn provokes the leakage of mitochondrial molecule cytochrome c to the cytosol, which triggers a cascade of adverse cytosol reactions. Upstream to this pathway, cerebellum under the condition of ethanol withdrawal has shown aberrant gene modifications through altered DNA methylation, histone acetylation, or microRNA expression. Interplay between these events and molecules may result in functional damage to cerebellar mitochondria and consequent neuronal degeneration, thereby contributing to motoric deficit. Mitochondria-targeting research may help develop a powerful new therapy to manage cerebellar disorders associated with hyperexcitatory CNS disorders like ethanol withdrawal.
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Affiliation(s)
- Marianna E Jung
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, 3500 Camp Bowie Blvd., Fort Worth, TX, 76107-2699, USA,
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10
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Costa PA, Poli JHZ, Sperotto NDM, Moura DJ, Saffi J, Nin MS, Barros HMT. Brain DNA damage and behavioral changes after repeated intermittent acute ethanol withdrawal by young rats. Psychopharmacology (Berl) 2015; 232:3623-36. [PMID: 26231496 DOI: 10.1007/s00213-015-4015-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Accepted: 06/30/2015] [Indexed: 01/10/2023]
Abstract
RATIONALE Alcohol addiction causes severe problems, and its deprivation may potentiate symptoms such as anxiety. Furthermore, ethanol is a neurotoxic agent that induces degeneration and the consequences underlying alcohol-mediated brain damage remain unclear. OBJECTIVES This study assessed the behavioral changes during acute ethanol withdrawal periods and determined the levels of DNA damage and reactive oxygen species (ROS) in multiple brain areas. METHODS Male Wistar rats were subjected to an oral ethanol self-administration procedure with a forced diet where they were offered 8% (v/v) ethanol solution for 21 days followed by five repeated 24-h cycles alternating between ethanol withdrawal and re-exposure. Control animals received an isocaloric control diet without ethanol. Behavioral changes were analyzed on ethanol withdrawal days in the open-field (OF) and elevated plus-maze (EPM) tests within the first 6 h of ethanol deprivation. The pre-frontal cortex, hypothalamus, striatum, hippocampus, and cerebellum were dissected for alkaline and neutral comet assays and for dichlorofluorescein ROS testing. RESULTS The repeated intermittent ethanol access enhanced solution intake and alcohol-seeking behavior. Decreased exploratory activity was observed in the OF test, and the animals stretched less in the EPM test. DNA single-strand breaks and ROS production were significantly higher in all structures evaluated in the ethanol-treated rats compared with controls. CONCLUSIONS The animal model of repeated intermittent ethanol access induced behavioral changes in rats, and this ethanol exposure model induced an increase in DNA single-strand breaks and ROS production in all brain areas. Our results suggest that these brain damages may influence future behaviors.
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Affiliation(s)
- Priscila A Costa
- Laboratory of Neuropsycopharmacology, Federal University of Health Sciences of Porto Alegre (UFCSPA), Porto Alegre, Rio Grande do Sul, Brazil
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The neuronal nitric oxide synthase (nNOS) gene and neuroprotection against alcohol toxicity. Cell Mol Neurobiol 2015; 35:449-61. [PMID: 25672665 DOI: 10.1007/s10571-015-0155-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 01/03/2015] [Indexed: 10/24/2022]
Abstract
When a mother abuses alcohol during pregnancy, the offspring can suffer a myriad of abnormalities, collectively known as fetal alcohol spectrum disorder (FASD). Foremost among these abnormalities is central nervous system dysfunction, which commonly manifests itself as mental retardation, clumsiness, hyperactivity, and poor attention span. These behavior problems are due, in large part, to alcohol-induced neuronal losses in the developing fetal brain. However, not all fetuses are equally affected by maternal alcohol consumption during pregnancy. While some fetuses are severely affected and develop hallmarks of FASD later in life, others exhibit no evident neuropathology or behavioral abnormalities. This variation is likely due, at least in part, to differences in fetal genetics. This review focuses on one particular gene, neuronal nitric oxide synthase, whose mutation worsens alcohol-induced neuronal death, both in vitro and in vivo. In addition, ectopic expression of the neuronal nitric oxide synthase gene protects neurons against alcohol toxicity. The gene encodes an enzyme that produces nitric oxide (NO), which facilitates the protective effects of neuronal growth factors and which underlies the ability of neurons to resist alcohol toxicity as they mature. Nitric oxide exerts its protective effects against alcohol via a specific signaling pathway, the NO-cGMP-PKG pathway. Pharmacologic manipulation of this pathway could be of therapeutic use in preventing or ameliorating FASD.
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Karacay B, Mahoney J, Plume J, Bonthius DJ. Genetic absence of nNOS worsens fetal alcohol effects in mice. II: microencephaly and neuronal losses. Alcohol Clin Exp Res 2015; 39:221-31. [PMID: 25664654 DOI: 10.1111/acer.12615] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 10/25/2014] [Indexed: 11/26/2022]
Abstract
BACKGROUND Prenatal alcohol exposure can kill developing neurons, leading to microencephaly and mental retardation. However, not all fetuses are equally vulnerable to alcohol's neurotoxic effects. While some fetuses are severely affected and are ultimately diagnosed with fetal alcohol syndrome (FAS), others have no evidence of neuropathology and are behaviorally normal. These widely different outcomes among alcohol-exposed fetuses are likely due, in part, to genetic differences. Some fetuses possess genotypes that make them much more vulnerable than others to alcohol's teratogenic effects. However, to date, only 1 gene has been identified whose mutation can worsen alcohol-induced behavioral deficits in an animal model of FAS. That gene is neuronal nitric oxide synthase (nNOS). The purpose of this study was to determine whether mutation of nNOS can likewise worsen alcohol-induced microencephaly and lead to permanent neuronal deficits. METHODS Wild-type and nNOS(-/-) mice received alcohol (0.0, 2.2, or 4.4 mg/g) daily over postnatal days (PDs) 4 to 9. Beginning on PD 85, the mice underwent a series of behavioral tests; the results of which are reported in the companion paper. The brains were then weighed, and stereological cell counts were performed on the cerebral cortex and hippocampal formation, which are the brain regions that mediate the aforementioned behavioral tasks. RESULTS Alcohol caused dose-dependent microencephaly, but only in the nNOS(-/-) mice and not in wild-type mice. Alcohol-induced neuronal losses were more severe in the nNOS(-/-) mice than in the wild-type mice in all of the brain regions examined, including the cerebral cortex, hippocampal CA3 subregion, hippocampal CA1 subregion, and dentate gyrus. CONCLUSIONS Targeted mutation of the nNOS gene increases the vulnerability of the developing brain to alcohol-induced growth restriction and neuronal losses. This increased neuropathology is associated with worsened behavioral dysfunction. The results demonstrate the critical importance of genotype in determining the outcome of developmental alcohol exposure.
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Affiliation(s)
- Bahri Karacay
- Department of Pediatrics , University of Iowa College of Medicine, Iowa City, Iowa
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13
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Karacay B, Bonthius NE, Plume J, Bonthius DJ. Genetic absence of nNOS worsens fetal alcohol effects in mice. I: behavioral deficits. Alcohol Clin Exp Res 2015; 39:212-20. [PMID: 25684045 PMCID: PMC4331461 DOI: 10.1111/acer.12616] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 10/25/2014] [Indexed: 12/12/2022]
Abstract
BACKGROUND Alcohol abuse during pregnancy often induces neuropsychological problems in the offspring, including learning disorders, attention deficits, and behavior problems, all of which are prominent components of fetal alcohol spectrum disorders (FASD). However, not all children who were exposed to alcohol in utero are equally affected by it. While some children have major deficits, others are spared. This unequal vulnerability is likely due largely to differences in fetal genetics. Some fetuses appear to have certain genotypes that make them much more prone to FASD. However, to date, no gene has been identified that worsens alcohol-induced brain dysfunction. Nitric oxide (NO) is a gaseous molecule that can protect developing neurons against alcohol-induced death. In the brain, NO is produced by neuronal nitric oxide synthase (nNOS). In this study, we examined whether homozygous mutation of the nNOS gene in mice worsens the behavioral deficits of developmental alcohol exposure. METHODS Wild-type and nNOS(-/-) mice received alcohol (0.0, 2.2, or 4.4 mg/g) daily over postnatal days (PDs) 4 to 9. Beginning on PD 85, the mice underwent a series of behavioral tests, including open field activity, the Morris water maze, and paired pulse inhibition. RESULTS For the wild-type mice, alcohol impaired performance only in the water maze. In contrast, for the nNOS(-/-) mice, alcohol impaired performance on all 3 tasks. Furthermore, the nNOS(-/-) mice were substantially more impaired than wild-type mice in their performance on all 3 of the behavioral tests and at both the low (2.2) and high (4.4) doses of alcohol. CONCLUSIONS Targeted disruption of the nNOS gene worsens the behavioral impact of developmental alcohol exposure and allows alcohol-induced learning problems to emerge that are not seen in wild type. This is the first demonstration that a specific genotype can interact with alcohol to worsen functional brain deficits in an animal model of FASD.
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Affiliation(s)
- Bahri Karacay
- Department of Pediatrics, University of Iowa College of Medicine, Iowa City, IA
| | - Nancy E. Bonthius
- Department of Pediatrics, University of Iowa College of Medicine, Iowa City, IA
| | - Jeffrey Plume
- Neuroscience Program, University of Iowa College of Medicine, Iowa City, IA
| | - Daniel J. Bonthius
- Department of Pediatrics, University of Iowa College of Medicine, Iowa City, IA
- Neuroscience Program, University of Iowa College of Medicine, Iowa City, IA
- Department of Neurology, University of Iowa College of Medicine, Iowa City, IA
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Bonthius DJ, Winters Z, Karacay B, Bousquet SL, Bonthius DJ. Importance of genetics in fetal alcohol effects: null mutation of the nNOS gene worsens alcohol-induced cerebellar neuronal losses and behavioral deficits. Neurotoxicology 2015; 46:60-72. [PMID: 25511929 PMCID: PMC4339445 DOI: 10.1016/j.neuro.2014.11.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 11/28/2014] [Accepted: 11/30/2014] [Indexed: 12/25/2022]
Abstract
The cerebellum is a major target of alcohol-induced damage in the developing brain. However, the cerebella of some children are much more seriously affected than others by prenatal alcohol exposure. As a consequence of in utero alcohol exposure, some children have substantial reductions in cerebellar volume and corresponding neurodevelopmental problems, including microencephaly, ataxia, and balance deficits, while other children who were exposed to similar alcohol quantities are spared. One factor that likely plays a key role in determining the impact of alcohol on the fetal cerebellum is genetics. However, no specific gene variant has yet been identified that worsens cerebellar function as a consequence of developmental alcohol exposure. Previous studies have revealed that mice carrying a homozygous mutation of the gene for neuronal nitric oxide synthase (nNOS-/- mice) have more severe acute alcohol-induced neuronal losses from the cerebellum than wild type mice. Therefore, the goals of this study were to determine whether alcohol induces more severe cerebellum-based behavioral deficits in nNOS-/- mice than in wild type mice and to determine whether these worsened behavior deficits are associated with worsened cerebellar neuronal losses. nNOS-/- mice and their wild type controls received alcohol (0.0, 2.2, or 4.4mg/g) daily over postnatal days 4-9. In adulthood, the mice underwent behavioral testing, followed by neuronal quantification. Alcohol caused dose-related deficits in rotarod and balance beam performance in both nNOS-/- and wild type mice. However, the alcohol-induced behavioral deficits were substantially worse in the nNOS-/- mice than in wild type. Likewise, alcohol exposure led to losses of Purkinje cells and cerebellar granule cells in mice of both genotypes, but the cell losses were more severe in the nNOS-/- mice than in wild type. Behavioral performances were correlated with neuronal number in the nNOS-/- mice, but not in wild type. Thus, homozygous mutation of the nNOS gene increases vulnerability to alcohol-induced cerebellar dysfunction and neuronal loss. nNOS is the first gene identified whose mutation worsens alcohol-induced cerebellar behavioral deficits.
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Affiliation(s)
| | - Zachary Winters
- Department of Pediatrics, University of Iowa College of Medicine, Iowa City, IA
| | - Bahri Karacay
- Department of Pediatrics, University of Iowa College of Medicine, Iowa City, IA
| | | | - Daniel J. Bonthius
- Department of Pediatrics, University of Iowa College of Medicine, Iowa City, IA
- Departments of Neurology, University of Iowa College of Medicine, Iowa City, IA
- Departments of Neuroscience Program, University of Iowa College of Medicine, Iowa City, IA
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Morton RA, Diaz MR, Topper LA, Valenzuela CF. Construction of vapor chambers used to expose mice to alcohol during the equivalent of all three trimesters of human development. J Vis Exp 2014. [PMID: 25046568 DOI: 10.3791/51839] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Exposure to alcohol during development can result in a constellation of morphological and behavioral abnormalities that are collectively known as Fetal Alcohol Spectrum Disorders (FASDs). At the most severe end of the spectrum is Fetal Alcohol Syndrome (FAS), characterized by growth retardation, craniofacial dysmorphology, and neurobehavioral deficits. Studies with animal models, including rodents, have elucidated many molecular and cellular mechanisms involved in the pathophysiology of FASDs. Ethanol administration to pregnant rodents has been used to model human exposure during the first and second trimesters of pregnancy. Third trimester ethanol consumption in humans has been modeled using neonatal rodents. However, few rodent studies have characterized the effect of ethanol exposure during the equivalent to all three trimesters of human pregnancy, a pattern of exposure that is common in pregnant women. Here, we show how to build vapor chambers from readily obtainable materials that can each accommodate up to six standard mouse cages. We describe a vapor chamber paradigm that can be used to model exposure to ethanol, with minimal handling, during all three trimesters. Our studies demonstrate that pregnant dams developed significant metabolic tolerance to ethanol. However, neonatal mice did not develop metabolic tolerance and the number of fetuses, fetus weight, placenta weight, number of pups/litter, number of dead pups/litter, and pup weight were not significantly affected by ethanol exposure. An important advantage of this paradigm is its applicability to studies with genetically-modified mice. Additionally, this paradigm minimizes handling of animals, a major confound in fetal alcohol research.
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Affiliation(s)
- Russell A Morton
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center;
| | - Marvin R Diaz
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center
| | - Lauren A Topper
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center
| | - C Fernando Valenzuela
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center
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Sulik KK. Fetal alcohol spectrum disorder: pathogenesis and mechanisms. HANDBOOK OF CLINICAL NEUROLOGY 2014; 125:463-75. [PMID: 25307590 DOI: 10.1016/b978-0-444-62619-6.00026-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
This chapter provides an overview of animal model-based studies that have generated information critical to our understanding of the pathogenesis and mechanisms underlying alcohol-induced birth defects, in particular those involving the brain. Focus is placed on the developing organism itself, rather than the mother, placenta, or other extraembryonic tissues. Components of the cascades of alcohol-induced damage that are considered herein are excessive cell death, changes in the cell cycle and proliferation, cell migration, cell morphogenesis, and gene expression as well as free radical damage and interference with cell signaling. The roles played by one or more of these various factors in the genesis of structural and functional birth defects are dependent upon alcohol exposure patterns and dosage, the involved tissue, and the prenatal stage(s) at the time of exposure. Technologic advances and rapidly increasing knowledge in the fields of genetics, cell, developmental, and neurobiology are critical to accurately piecing together experimental evidence in refining our understanding of the genesis of alcohol-induced birth defects, to the planning and execution of future studies, and to applying the knowledge gained to diminish the severity or occurrence of fetal alcohol spectrum disorder.
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Affiliation(s)
- Kathleen K Sulik
- Department of Cell Biology and Physiology and Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, NC, USA.
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Cole GJ, Zhang C, Ojiaku P, Bell V, Devkota S, Mukhopadhyay S. Effects of ethanol exposure on nervous system development in zebrafish. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 299:255-315. [PMID: 22959306 DOI: 10.1016/b978-0-12-394310-1.00007-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Alcohol (ethanol) is a teratogen that adversely affects nervous system development in a wide range of animal species. In humans numerous congenital abnormalities arise as a result of fetal alcohol exposure, leading to a spectrum of disorders referred to as fetal alcohol spectrum disorder (FASD). These abnormalities include craniofacial defects as well as neurological defects that affect a variety of behaviors. These human FASD phenotypes are reproduced in the rodent central nervous system (CNS) following prenatal ethanol exposure. While the study of ethanol effects on zebrafish development has been more limited, several studies have shown that different strains of zebrafish exhibit differential susceptibility to ethanol-induced cyclopia, as well as behavioral deficits. Molecular mechanisms underlying the effects of ethanol on CNS development also appear to be shared between rodent and zebrafish. Thus, zebrafish appear to recapitulate the observed effects of ethanol on human and mouse CNS development, indicating that zebrafish can serve as a complimentary developmental model system to study the molecular basis of FASD. Recent studies examining the effect of ethanol exposure on zebrafish nervous system development are reviewed, with an emphasis on attempts to elucidate possible molecular pathways that may be impacted by developmental ethanol exposure. Recent work from our laboratories supports a role for perturbed extracellular matrix function in the pathology of ethanol exposure during zebrafish CNS development. The use of the zebrafish model to assess the effects of ethanol exposure on adult nervous system function as manifested by changes in zebrafish behavior is also discussed.
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Affiliation(s)
- Gregory J Cole
- Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC, USA
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18
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Yuan H, Zhang W, Li H, Chen C, Liu H, Li Z. Neuroprotective effects of resveratrol on embryonic dorsal root ganglion neurons with neurotoxicity induced by ethanol. Food Chem Toxicol 2013; 55:192-201. [DOI: 10.1016/j.fct.2012.12.052] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 12/06/2012] [Accepted: 12/31/2012] [Indexed: 11/16/2022]
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Saito M, Saito M. Involvement of sphingolipids in ethanol neurotoxicity in the developing brain. Brain Sci 2013; 3:670-703. [PMID: 24961420 PMCID: PMC4061845 DOI: 10.3390/brainsci3020670] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 03/30/2013] [Accepted: 04/12/2013] [Indexed: 12/16/2022] Open
Abstract
Ethanol-induced neuronal death during a sensitive period of brain development is considered one of the significant causes of fetal alcohol spectrum disorders (FASD). In rodent models, ethanol triggers robust apoptotic neurodegeneration during a period of active synaptogenesis that occurs around the first two postnatal weeks, equivalent to the third trimester in human fetuses. The ethanol-induced apoptosis is mitochondria-dependent, involving Bax and caspase-3 activation. Such apoptotic pathways are often mediated by sphingolipids, a class of bioactive lipids ubiquitously present in eukaryotic cellular membranes. While the central role of lipids in ethanol liver toxicity is well recognized, the involvement of sphingolipids in ethanol neurotoxicity is less explored despite mounting evidence of their importance in neuronal apoptosis. Nevertheless, recent studies indicate that ethanol-induced neuronal apoptosis in animal models of FASD is mediated or regulated by cellular sphingolipids, including via the pro-apoptotic action of ceramide and through the neuroprotective action of GM1 ganglioside. Such sphingolipid involvement in ethanol neurotoxicity in the developing brain may provide unique targets for therapeutic applications against FASD. Here we summarize findings describing the involvement of sphingolipids in ethanol-induced apoptosis and discuss the possibility that the combined action of various sphingolipids in mitochondria may control neuronal cell fate.
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Affiliation(s)
- Mariko Saito
- Division of Neurochemistry, Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA.
| | - Mitsuo Saito
- Division of Analytical Psychopharmacology, Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA.
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Kaddour H, Hamdi Y, Vaudry D, Basille M, Desrues L, Leprince J, Castel H, Vaudry H, Tonon MC, Amri M, Masmoudi-Kouki O. The octadecaneuropeptide ODN prevents 6-hydroxydopamine-induced apoptosis of cerebellar granule neurons through a PKC-MAPK-dependent pathway. J Neurochem 2013; 125:620-33. [PMID: 23286644 DOI: 10.1111/jnc.12140] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 12/31/2012] [Accepted: 01/02/2013] [Indexed: 12/27/2022]
Abstract
Oxidative stress, induced by various neurodegenerative diseases, initiates a cascade of events leading to apoptosis, and thus plays a critical role in neuronal injury. In this study, we have investigated the potential neuroprotective effect of the octadecaneuropeptide (ODN) on 6-hydroxydopamine (6-OHDA)-induced oxidative stress and apoptosis in cerebellar granule neurons (CGN). ODN, which is produced by astrocytes, is an endogenous ligand for both central-type benzodiazepine receptors (CBR) and a metabotropic receptor. Incubation of neurons with subnanomolar concentrations of ODN (10⁻¹⁸ to 10⁻¹² M) inhibited 6-OHDA-evoked cell death in a concentration-dependent manner. The effect of ODN on neuronal survival was abrogated by the metabotropic receptor antagonist, cyclo₁₋₈ [DLeu⁵]OP, but not by a CBR antagonist. ODN stimulated polyphosphoinositide turnover and ERK phosphorylation in CGN. The protective effect of ODN against 6-OHDA toxicity involved the phospholipase C/ERK MAPK transduction cascade. 6-OHDA treatment induced an accumulation of reactive oxygen species, an increase of the expression of the pro-apoptotic gene Bax, a drop of the mitochondrial membrane potential and a stimulation of caspase-3 activity. Exposure of 6-OHDA-treated cells to ODN blocked all the deleterious effects of the toxin. Taken together, these data demonstrate for the first time that ODN is a neuroprotective agent that prevents 6-OHDA-induced oxidative stress and apoptotic cell death.
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Affiliation(s)
- Hadhemi Kaddour
- Laboratory of Functional Neurophysiology and Pathology, Research Unit, UR/11ES09, Department of Biological Sciences, Faculty of Science of Tunis, University Tunis El Manar, Tunis, Tunisia
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21
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Luo J. Mechanisms of ethanol-induced death of cerebellar granule cells. THE CEREBELLUM 2012; 11:145-54. [PMID: 20927663 DOI: 10.1007/s12311-010-0219-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Maternal ethanol exposure during pregnancy may cause fetal alcohol spectrum disorders (FASD). FASD is the leading cause of mental retardation. The most deleterious effect of fetal alcohol exposure is inducing neuroapoptosis in the developing brain. Ethanol-induced loss of neurons in the central nervous system underlies many of the behavioral deficits observed in FASD. The cerebellum is one of the brain areas that are most susceptible to ethanol during development. Ethanol exposure causes a loss of both cerebellar Purkinje cells and granule cells. This review focuses on the toxic effect of ethanol on cerebellar granule cells (CGC) and the underlying mechanisms. Both in vitro and in vivo studies indicate that ethanol induces apoptotic death of CGC. The vulnerability of CGC to ethanol-induced death diminishes over time as neurons mature. Several mechanisms for ethanol-induced apoptosis of CGC have been suggested. These include inhibition of N-methyl-D-aspartate receptors, interference with signaling by neurotrophic factors, induction of oxidative stress, modulation of retinoid acid signaling, disturbance of potassium channel currents, thiamine deficiency, and disruption of translational regulation. Cultures of CGC provide an excellent system to investigate cellular/molecular mechanisms of ethanol-induced neurodegeneration and to evaluate interventional strategies. This review will also discuss the approaches leading to neuroprotection against ethanol-induced neuroapoptosis.
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Affiliation(s)
- Jia Luo
- Department of Internal Medicine, University of Kentucky College of Medicine, Lexington, KY 40536, USA.
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Heaton MB, Siler-Marsiglio K, Paiva M, Kotler A, Rogozinski J, Kubovec S, Coursen M, Madorsky V. Ethanol influences on Bax associations with mitochondrial membrane proteins in neonatal rat cerebellum. Dev Neurobiol 2012; 73:127-41. [PMID: 22767450 DOI: 10.1002/dneu.22042] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 05/13/2012] [Accepted: 06/13/2012] [Indexed: 12/22/2022]
Abstract
These studies investigated interactions taking place at the mitochondrial membrane in neonatal rat cerebellum following ethanol exposure and focused on interactions between proapoptotic Bax and proteins of the permeability transition pore (PTP), voltage-dependent anion channel (VDAC) and adenine nucleotide translocator (ANT) of the outer and inner mitochondrial membranes, respectively. Cultured cerebellar granule cells were used to assess the role of these interactions in ethanol neurotoxicity. Analyses were made at the age of maximal cerebellar ethanol vulnerability (P4), compared to the later age of relative resistance (P7), to determine whether differential ethanol sensitivity was mirrored by differences in these molecular interactions. We found that, following ethanol exposure, Bax proapoptotic associations with both VDAC and ANT were increased, particularly at the age of greater ethanol sensitivity, and these interactions were sustained at this age for at least 2 h postexposure. Since Bax:VDAC interactions disrupt protective VDAC interactions with mitochondrial hexokinase (HXK), we also assessed VDAC:HXK associations following ethanol treatment and found such interactions were altered by ethanol treatment, but only at 2 h postexposure and only in the P4, ethanol-sensitive cerebellum. Ethanol neurotoxicity in cultured neuronal preparations was abolished by pharmacological inhibition of both VDAC and ANT interactions with Bax but not by a Bax channel blocker. Therefore, we conclude that, at this age, within the constraints of our experimental model, a primary mode of Bax-induced initiation of the apoptosis cascade following ethanol insult involves interactions with proteins of the PTP complex and not channel formation independent of PTP constituents.
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Affiliation(s)
- Marieta Barrow Heaton
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, Florida 32610-0244, USA.
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Wang X, Ke Z, Chen G, Xu M, Bower KA, Frank JA, Zhang Z, Shi X, Luo J. Cdc42-dependent activation of NADPH oxidase is involved in ethanol-induced neuronal oxidative stress. PLoS One 2012; 7:e38075. [PMID: 22662267 PMCID: PMC3360628 DOI: 10.1371/journal.pone.0038075] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 04/30/2012] [Indexed: 01/13/2023] Open
Abstract
It has been suggested that excessive reactive oxygen species (ROS) and oxidative stress play an important role in ethanol-induced damage to both the developing and mature central nervous system (CNS). The mechanisms underlying ethanol-induced neuronal ROS, however, remain unclear. In this study, we investigated the role of NADPH oxidase (NOX) in ethanol-induced ROS generation. We demonstrated that ethanol activated NOX and inhibition of NOX reduced ethanol-promoted ROS generation. Ethanol significantly increased the expression of p47phox and p67phox, the essential subunits for NOX activation in cultured neuronal cells and the cerebral cortex of infant mice. Ethanol caused serine phosphorylation and membrane translocation of p47phox and p67phox, which were prerequisites for NOX assembly and activation. Knocking down p47phox with the small interfering RNA was sufficient to attenuate ethanol-induced ROS production and ameliorate ethanol-mediated oxidative damage, which is indicated by a decrease in protein oxidation and lipid peroxidation. Ethanol activated cell division cycle 42 (Cdc42) and overexpression of a dominant negative (DN) Cdc42 abrogate ethanol-induced NOX activation and ROS generation. These results suggest that Cdc42-dependent NOX activation mediates ethanol-induced oxidative damages to neurons.
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Affiliation(s)
- Xin Wang
- Graduate Center for Toxicology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Zunji Ke
- Department of Internal Medicine, University of Kentucky, Lexington, Kentucky, United States of America
| | - Gang Chen
- Department of Internal Medicine, University of Kentucky, Lexington, Kentucky, United States of America
| | - Mei Xu
- Department of Internal Medicine, University of Kentucky, Lexington, Kentucky, United States of America
| | - Kimberly A. Bower
- Department of Internal Medicine, University of Kentucky, Lexington, Kentucky, United States of America
| | - Jacqueline A. Frank
- Department of Internal Medicine, University of Kentucky, Lexington, Kentucky, United States of America
| | - Zhuo Zhang
- Graduate Center for Toxicology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Xianglin Shi
- Graduate Center for Toxicology, University of Kentucky, Lexington, Kentucky, United States of America
- * E-mail: (JL); (XS)
| | - Jia Luo
- Department of Internal Medicine, University of Kentucky, Lexington, Kentucky, United States of America
- * E-mail: (JL); (XS)
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Heaton MB, Paiva M, Kubovic S, Kotler A, Rogozinski J, Swanson E, Madorsky V, Posados M. Differential effects of ethanol on c-jun N-terminal kinase, 14-3-3 proteins, and Bax in postnatal day 4 and postnatal day 7 rat cerebellum. Brain Res 2011; 1432:15-27. [PMID: 22169498 DOI: 10.1016/j.brainres.2011.11.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 11/01/2011] [Accepted: 11/03/2011] [Indexed: 11/18/2022]
Abstract
These studies investigated ethanol effects on upstream cellular elements and interactions which contribute to Bax-related apoptosis in neonatal rat cerebellum at ages of peak ethanol sensitivity (postnatal day 4 [P4]), compared to later ages of relative resistance (P7). Analyses were made of basal levels of the pro-apoptotic c-jun N-terminal kinase (JNK), Bax, and the 14-3-3 anchoring proteins, as well as the responsiveness of these substances to ethanol at P4 versus P7. Dimerization of Bax with 14-3-3 was also investigated at the two ages following ethanol treatment, a process which sequesters Bax in the cytosol, thus inhibiting its mitochondrial translocation and disruption of the mitochondrial membrane potential. Cultured cerebellar granule cells were used to examine the protective potential of JNK inhibition on ethanol-mediated cell death. Basal levels of JNK were significantly higher at P4 than P7, but no differences in the other proteins were found. Activated JNK, and cytosolic and mitochondrially-translocated Bax were increased in P4 but not P7 animals following ethanol exposure, while protective 14-3-3 proteins were increased only at P7. Ethanol treatment resulted in decreases in Bax:14-3-3 heterodimers at P4, but not at P7. Inhibition of JNK activity in vitro provided partial protection against ethanol neurotoxicity. Thus, differential temporal vulnerability to ethanol in this CNS region correlates with differences in both levels of apoptosis-related substances (e.g., JNK), and differential cellular responsiveness, favoring apoptosis at the most sensitive age and survival at the resistant age. The upstream elements contributing to this vulnerability can be targets for future therapeutic strategies.
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Affiliation(s)
- Marieta Barrow Heaton
- Department of Neuroscience, University of Florida College of Medicine, USA; McKnight Brain Institute, USA.
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Balaszczuk V, Bender C, Pereno GL, Beltramino CA. Alcohol-induced neuronal death in central extended amygdala and pyriform cortex during the postnatal period of the rat. Int J Dev Neurosci 2011; 29:733-42. [PMID: 21664448 DOI: 10.1016/j.ijdevneu.2011.05.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 05/12/2011] [Accepted: 05/25/2011] [Indexed: 02/06/2023] Open
Abstract
Mothers who consume alcohol during pregnancy may cause a neurotoxic syndrome defined as fetal alcohol spectrum disorder (FASD) in their offspring. This disorder is characterized by reduction in brain size, cognitive deficits and emotional/social disturbances. These alterations are thought to be caused by an alcohol-induced increase in apoptosis during neurodevelopment. Little is known about neuroapoptosis in the central extended amygdala and the pyriform cortex, which are key structures in emotional/social behaviors. The goal of this study was to determine the vulnerability of neuroapoptotic alcohol effects in those areas. Rats were administered alcohol (2.5g/kg s.c. at 0 and 2h) or saline on postnatal day (PND) 7, 15 and 20. The Amino-cupric-silver technique was used to evaluate neurodegeneration and immunohistochemistry to detect activated caspases 3-8 and 9 at 2h, 4, 6, 8, 12 and 24h after drug administration. We measured blood alcohol levels each hour, from 2 to 8h post second administration of alcohol in each of the ages studied. Results showed alcohol induced apoptotic neurodegeneration in the central extended amygdala on PND 7 and 15, and pyriform cortex on PND 7, 15 and 20. These structures showed activation of caspase 3 and 9 but not of caspase 8 suggesting that alcohol-induced apoptosis could occur by the intrinsic pathway. The pharmacokinetic differences between ages did not associate with the neurodegeneration age dependence. In conclusion, these limbic areas are damaged by alcohol, and each one has their own window of vulnerability during the postnatal period. The possible implications in emotional/social features in FASD are discussed.
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Affiliation(s)
- V Balaszczuk
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, Friuli, Córdoba, Argentina.
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Kane CJ, Phelan KD, Han L, Smith RR, Xie J, Douglas JC, Drew PD. Protection of neurons and microglia against ethanol in a mouse model of fetal alcohol spectrum disorders by peroxisome proliferator-activated receptor-γ agonists. Brain Behav Immun 2011; 25 Suppl 1:S137-45. [PMID: 21376806 PMCID: PMC3104506 DOI: 10.1016/j.bbi.2011.02.016] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 02/25/2011] [Accepted: 02/27/2011] [Indexed: 02/05/2023] Open
Abstract
Fetal alcohol spectrum disorders (FASD) result from ethanol exposure to the developing fetus and are the most common cause of mental retardation in the United States. These disorders are characterized by a variety of neurodevelopmental and neurodegenerative anomalies which result in significant lifetime disabilities. Thus, novel therapies are required to limit the devastating consequences of FASD. Neuropathology associated with FASD can occur throughout the central nervous system (CNS), but is particularly well characterized in the developing cerebellum. Rodent models of FASD have previously demonstrated that both Purkinje cells and granule cells, which are the two major types of neurons in the cerebellum, are highly susceptible to the toxic effects of ethanol. The current studies demonstrate that ethanol decreases the viability of cultured cerebellar granule cells and microglial cells. Interestingly, microglia have dual functionality in the CNS. They provide trophic and protective support to neurons. However, they may also become pathologically activated and produce inflammatory molecules toxic to parenchymal cells including neurons. The findings in this study demonstrate that the peroxisome proliferator-activated receptor-γ agonists 15-deoxy-Δ12,15 prostaglandin J2 and pioglitazone protect cultured granule cells and microglia from the toxic effects of ethanol. Furthermore, investigations using a newly developed mouse model of FASD and stereological cell counting methods in the cerebellum elucidate that ethanol administration to neonates is toxic to both Purkinje cell neurons as well as microglia, and that in vivo administration of PPAR-γ agonists protects these cells. In composite, these studies suggest that PPAR-γ agonists may be effective in limiting ethanol-induced toxicity to the developing CNS.
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27
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Heaton MB, Paiva M, Siler-Marsiglio K. Ethanol influences on Bax translocation, mitochondrial membrane potential, and reactive oxygen species generation are modulated by vitamin E and brain-derived neurotrophic factor. Alcohol Clin Exp Res 2011; 35:1122-33. [PMID: 21332533 DOI: 10.1111/j.1530-0277.2011.01445.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND This study investigated ethanol influences on intracellular events that predispose developing neurons toward apoptosis and the capacity of the antioxidant α-tocopherol (vitamin E) and the neurotrophin brain-derived neurotrophic factor (BDNF) to modulate these effects. Assessments were made of the following: (i) ethanol-induced translocation of the pro-apoptotic Bax protein to the mitochondrial membrane, a key upstream event in the initiation of apoptotic cell death; (ii) disruption of the mitochondrial membrane potential (MMP) as a result of ethanol exposure, an important process in triggering the apoptotic cascade; and (iii) generation of damaging reactive oxygen species (ROS) as a function of ethanol exposure. METHODS These interactions were investigated in cultured postnatal day 8 neonatal rat cerebellar granule cells, a population vulnerable to developmental ethanol exposure in vivo and in vitro. Bax mitochondrial translocation was analyzed via subcellular fractionation followed by Western blot, and mitochondrial membrane integrity was determined using the lipophilic dye, JC-1, that exhibits potential-dependent accumulation in the mitochondrial membrane as a function of the MMP. RESULTS Brief ethanol exposure in these preparations precipitated Bax translocation, but both vitamin E and BDNF reduced this effect to control levels. Ethanol treatment also resulted in a disturbance of the MMP, and this effect was blunted by the antioxidant and the neurotrophin. ROS generation was enhanced by a short ethanol exposure in these cells, but the production of these harmful free radicals was diminished to control levels by cotreatment with either vitamin E or BDNF. CONCLUSIONS These results indicate that both antioxidants and neurotrophic factors have the potential to ameliorate ethanol neurotoxicity and suggest possible interventions that could be implemented in preventing or lessening the severity of the damaging effects of ethanol in the developing central nervous system seen in the fetal alcohol syndrome (FAS).
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Affiliation(s)
- Marieta B Heaton
- Department of Neuroscience, McKnight Brain Institute, Center for Alcohol Research, University of Florida College of Medicine, Gainesville, FL 32610, USA.
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28
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Cell Death as a Regulator of Cerebellar Histogenesis and Compartmentation. THE CEREBELLUM 2010; 10:373-92. [DOI: 10.1007/s12311-010-0222-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Yan D, Dong J, Sulik KK, Chen SY. Induction of the Nrf2-driven antioxidant response by tert-butylhydroquinone prevents ethanol-induced apoptosis in cranial neural crest cells. Biochem Pharmacol 2010; 80:144-9. [PMID: 20223225 PMCID: PMC2860686 DOI: 10.1016/j.bcp.2010.03.004] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 03/02/2010] [Accepted: 03/02/2010] [Indexed: 11/23/2022]
Abstract
Previous studies have shown that ethanol exposure causes apoptosis in cranial neural crest cells (NCCs), an ethanol-sensitive cell population implicated in Fetal Alcohol Spectrum Disorders (FASD). Additionally, induction of endogenous antioxidants through activation of nuclear factor-erythroid 2-related factor 2 (Nrf2) has been shown to prevent oxidative stress and apoptosis in ethanol-exposed mouse embryos. The objective of this study was to test whether tert-butylhydroquinone (tBHQ), an Nrf2 inducer, can protect NCCs against ethanol-induced apoptosis. Ethanol exposure was shown to cause a moderate increase in the protein expression of Nrf2 and its downstream antioxidants in the NCCs. Treatment of NCCs with tBHQ alone significantly increased the protein expression of Nrf2 and its downstream antioxidants and also significantly increased the activities of the antioxidant enzymes. In NCCs exposed to ethanol, the tBHQ-mediated antioxidant response prevented oxidative stress and apoptosis. These results clearly demonstrate that the activation of Nrf2 signaling confers protection against ethanol-induced apoptosis in NCCs.
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Affiliation(s)
- Dong Yan
- Bowles Center for Alcohol Studies & Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Jian Dong
- Bowles Center for Alcohol Studies & Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Kathleen K. Sulik
- Bowles Center for Alcohol Studies & Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Shao-yu Chen
- Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine, Peoria, IL 61656, USA
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The role of NOX enzymes in ethanol-induced oxidative stress and apoptosis in mouse embryos. Toxicol Lett 2009; 193:94-100. [PMID: 20026259 DOI: 10.1016/j.toxlet.2009.12.012] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Revised: 12/10/2009] [Accepted: 12/11/2009] [Indexed: 01/21/2023]
Abstract
Reactive oxygen species (ROS) play an important role in ethanol-induced apoptosis and teratogenesis. However, the major sources of ROS in ethanol-exposed embryos have remained undefined. This study was conducted to determine the role of NADPH oxidase (NOX) in ethanol-induced oxidative stress and apoptosis in mouse embryos. Analyses of mRNA expression indicated that ethanol treatment resulted in a significant increase in mRNA expression of NOX catalytic subunit Duox-1 in gestational day 9 (GD 9:0) mouse embryos. Ethanol exposure also resulted in significant increases in mRNA expression of NOX regulatory subunits, p22phox, p67phox, NOXA1 and NOXO1. In addition, a significant increase in NOX enzyme activity was found in the ethanol-exposed embryos as compared to controls. Co-treatment with the NOX inhibitor, diphenyleneiodonium (DPI), significantly prevented ethanol-induced increases in NOX enzyme activity, ROS generation and oxidative DNA damage in ethanol-exposed embryos. DPI treatment also resulted in a reduction in caspase-3 activation, decreased caspase-3 activity and diminished prevalence of apoptosis in ethanol-exposed embryos. These results support the hypothesis that NOX is a critical source of ROS in ethanol-exposed embryos and that it plays an important role in ethanol-induced oxidative stress and pathogenesis.
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Alcohol exposure on postnatal day 5 induces Purkinje cell loss and evidence of Purkinje cell degradation in lobule I of rat cerebellum. Alcohol 2008; 42:295-302. [PMID: 18400452 DOI: 10.1016/j.alcohol.2008.01.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2007] [Revised: 01/28/2008] [Accepted: 01/29/2008] [Indexed: 11/20/2022]
Abstract
The reduction in neuron number in specific brain regions is one of the most destructive aspects of alcohol-induced developmental brain injury, and its occurrence depends on the timing, pattern, and dose of maternal alcohol consumption during pregnancy. The purpose of this investigation was to quantify the dose-response aspect of Purkinje cell loss and rapid cellular degradation indicative of Purkinje cell loss following a single alcohol exposure on postnatal day 5 in lobule I, a lobule that has been shown to be vulnerable to alcohol-induced injury during cerebellar development. Fluoro-Jade B was used to identify Purkinje cell degeneration in 2-h intervals during the first 24h following the single alcohol exposure. At the end of 24h, stereology cell counting techniques were used to estimate the number of Purkinje cells in lobule I of the cerebellum. Significant Fluoro-Jade B labeling of lobule I Purkinje cells began at 12-h postexposure in the 6.0-g/kg group with continued significant expression of the marker at the 16- and 18-h time points. Notably, the magnitude of Fluoro-Jade B expression in the 6.0-g/kg group remained high during the period between 12 and 24h even though the difference between the 6.0-g/kg group and other groups did not reach statistical significance at the 14-, 20-, and 24-h time points. On postnatal day 6, 24h following the alcohol exposure, rats exposed to the highest alcohol dose (6.0 g/kg) had lost significantly more Purkinje cells than those in the nutritional or caloric control to the highest dose of alcohol group. These results are suggestive of a unique relationship among the quantity of alcohol, the onset and duration of cell degradation, and the degree of eventual cell loss. Given that cerebellar Purkinje cells (and many developing neurons) are vulnerable to alcohol-induced neuronal loss within hours of a single alcohol insult, women should be counseled to avoid drinking alcohol in a manner that significantly increases blood alcohol levels during pregnancy (e.g., binge drinking).
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Jaatinen P, Rintala J. Mechanisms of ethanol-induced degeneration in the developing, mature, and aging cerebellum. THE CEREBELLUM 2008; 7:332-47. [DOI: 10.1007/s12311-008-0034-z] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Accepted: 08/01/2007] [Indexed: 11/30/2022]
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Kane CJM, Chang JY, Roberson PK, Garg TK, Han L. Ethanol exposure of neonatal rats does not increase biomarkers of oxidative stress in isolated cerebellar granule neurons. Alcohol 2008; 42:29-36. [PMID: 18249267 DOI: 10.1016/j.alcohol.2007.10.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2006] [Revised: 03/20/2007] [Accepted: 10/09/2007] [Indexed: 11/29/2022]
Abstract
Oxidative stress is a candidate mechanism for ethanol neuropathology in fetal alcohol spectrum disorders. Oxidative stress often involves production of reactive oxygen species (ROS), deterioration of the mitochondrial membrane potential (MMP), and cell death. Previous studies have produced conflicting results regarding the role of oxidative stress and the benefit of antioxidants in ethanol neuropathology in the developing brain. This study investigated the hypothesis that ethanol neurotoxicity involves production of ROS with negative downstream consequences for MMP and neuron survival. This was modeled in neonatal rats at postnatal day 4 (P4) and P14. It is well established that granule neurons in the rat cerebellar cortex are more vulnerable to ethanol neurotoxicity on P4 than at later ages. Thus, it was hypothesized that ethanol produces more oxidative stress and its negative consequences on P4 than on P14. A novel experimental approach was used in which ethanol was administered to animals in vivo (gavage 6g/kg), granule neurons were isolated 2-24h post-treatment, and ROS production and relative MMP were immediately assessed in the viable cells. Cells were also placed in culture and survival was measured 24h later. The results revealed that ethanol did not induce granule cells to produce ROS, cause deterioration of neuronal MMP, or cause neuron death when compared to vehicle controls. Further, granule neurons from neither P4 nor P14 animals mounted an oxidative response to ethanol. These findings do not support the hypothesis that oxidative stress is obligate to granule neuron death after ethanol exposure in the neonatal rat brain. Other investigators have reached a similar conclusion using either brain homogenates or cell cultures. In this context, it is likely that oxidative stress is not the sole and perhaps not the principal mechanism of ethanol neurotoxicity for cerebellar granule neurons during this stage of brain development.
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Affiliation(s)
- Cynthia J M Kane
- Department of Neurobiology and Developmental Sciences, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
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Krzyzanski W, Oberdoester J, Rabin RA. Mechanism of ethanol enhancement of apoptosis and caspase activation in serum-deprived PC12 cells. Life Sci 2007; 81:756-64. [PMID: 17706724 DOI: 10.1016/j.lfs.2007.07.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2007] [Revised: 07/06/2007] [Accepted: 07/12/2007] [Indexed: 01/22/2023]
Abstract
Neuronal death is one of the most prominent consequences of alcohol exposure during development. Ethanol-induced neuronal death appears to involve apoptosis. The objective of the present study was to characterize the effect of ethanol on neuronal cell viability and to determine the mechanism by which ethanol enhances apoptosis in neural cells. For these studies the rat pheochromocytoma (PC12) cells were used. PC12 cells were incubated for 24 h in the presence or absence of 100 mM ethanol. Apoptosis was induced by serum withdrawal. Ethanol in the presence of serum-containing media did not alter cell viability, while incubation of PC12 cells in serum-free media resulted in a significant increase in cell death that was further significantly increased by 35% in cells exposed to ethanol. The temporal response of the PC12 cells to serum withdrawal was studied over a period of 22 h. At least 18 h of ethanol exposure was necessary to observe a significant increase in death for cells incubated in serum-free media. An increase in the caspase-3 activity in PC12 cells deprived of serum was observed that was further increased by ethanol exposure. This increase of caspase-3 activity was correlated with an enhancement of caspase-9 activity. Ethanol exposure increased the amount of cytosolic cytochrome c in PC12 cells incubated in serum-free media but did not alter the level of cytochrome c in cells incubated in serum. Finally, a 26% increase was observed in the number of cells with depolarized mitochondria due to ethanol treatment. The present study implicates an increase in the mitochondrial outer membrane permeability as a potential mechanism of enhancement of apoptosis in serum-deprived PC12 cells by ethanol.
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Affiliation(s)
- Wojciech Krzyzanski
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York, United States
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Mello CF, Rubin MA, Sultana R, Barron S, Littleton JM, Butterfield DA. Difluoromethylornithine decreases long-lasting protein oxidation induced by neonatal ethanol exposure in the hippocampus of adolescent rats. Alcohol Clin Exp Res 2007; 31:887-94. [PMID: 17386069 DOI: 10.1111/j.1530-0277.2007.00369.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Ethanol exposure and withdrawal during central nervous system development can cause oxidative stress and produce severe and long-lasting behavioral and morphological alterations in which polyamines seem to play an important role. However, it is not known if early ethanol exposure causes long-lasting protein oxidative damage and if polyamines play a role in such a deleterious effect of ethanol. METHODS In this study we investigated the effects of early ethanol exposure (6 g/kg/d, by gavage), from postnatal day (PND) 1 to 8, and of the administration of difluoromethylornithine (DFMO, 500 mg/kg, i.p., on PND 8), a polyamine biosynthesis inhibitor, on the extent of oxidative modification of proteins. Indices of oxidative modification of proteins included protein carbonyls, 3-nitrotyrosine (3-NT), and protein bound 4-hydroxynonenal (HNE) in the hippocampus, cerebellum, hypothalamus, striatum, and cerebral cortex of Sprague-Dawley rats at PND 40. RESULTS Both ethanol and DFMO administration alone increased protein carbonyl immunoreactivity in the hippocampus at PND 40, but the combination of DFMO and ethanol resulted in no effect on protein carbonyl levels. No alterations in the content of protein-bound HNE, 3-NT, or carbonyl were found in any other cerebral structure. CONCLUSIONS These results suggest that the hippocampus is selectively affected by early ethanol exposure and by polyamine synthesis inhibition. In addition, the results suggest a role for polyamines in the long-lasting increase of protein carbonyls induced by ethanol exposure and withdrawal.
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Affiliation(s)
- Carlos Fernando Mello
- Departamento de Fisiologia e Farmacologia, Universidade Federal de Santa Maria, Santa Maria, Brazil
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Siler-Marsiglio KI, Madorsky I, Pan Q, Paiva M, Neeley AW, Shaw G, Heaton MB. Effects of Acute Ethanol Exposure on Regulatory Mechanisms of Bcl-2-Associated Apoptosis Promoter, Bad, in Neonatal Rat Cerebellum: Differential Effects During Vulnerable and Resistant Developmental Periods. Alcohol Clin Exp Res 2006; 30:1031-8. [PMID: 16737462 DOI: 10.1111/j.1530-0277.2006.000126.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Prenatal alcohol exposure produces anatomical and behavioral abnormalities associated with fetal alcohol syndrome (FAS). Animal FAS models have demonstrated temporal windows of vulnerability in the developing cerebellum, with substantial ethanol (EtOH)-mediated apoptotic activation during these periods. In rodents, the cerebellum is most sensitive to EtOH on postnatal days 4 to 6 (P4 to P6). At slightly later ages (P7 and later), this region is less vulnerable to EtOH. The present study investigated EtOH effects on mechanisms related to activities of Bad, a proapoptotic member of the Bcl-2 gene family, to further characterize processes underlying these disparate EtOH sensitivities. In healthy cells, Bad is retained in the cytosol by association with 14-3-3, a primarily cytosolic protein. Bad promotes apoptosis by disassociating from 14-3-3 and sequestering Bcl-xL through heterodimerization. This dimerization prevents the neutralizing association of Bcl-xL with Bax, freeing Bax to perform in a prodeath manner. Caspase-dependent cleavage of Bad to a 15-kDa fragment increases its proapoptogenic capacity. METHODS Two hours following EtOH exposure of P4 and P7 animals via inhalation, we determined how exposure affects intracellular localization and proteolytic cleavage of Bad and expression of cerebellar 14-3-3, using subcellular fractionation and Western blot techniques. Ethanol effects on interactions between Bad and 14-3-3 or Bcl-xL at the more vulnerable and less vulnerable ages were determined using an enzyme-linked immunosorbent assay-based technique to detect native protein-protein interactions. RESULTS At P4, EtOH increased mitochondrial localization of Bad, expression of a 15-kDa fragment recognized by Bad antibody, and formation of Bad:Bcl-xL complexes. At that more vulnerable age, EtOH also decreased formation of Bad:14-3-3 complexes. At P7, EtOH increased Bad:14-3-3 complexes and reduced Bad:Bcl-xL complexes. Cytosolic 14-3-3 remained unchanged by EtOH at P4 and P7. CONCLUSIONS Ethanol-induced alterations of Bad-related mechanisms at P4 favor a prodeath response. EtOH does not influence these same mechanisms in a manner that promotes cell death at P7. Divergent Bad-related responses at these 2 developmental ages likely contribute to their differential EtOH vulnerability.
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Affiliation(s)
- Kendra I Siler-Marsiglio
- Department of Neuroscience, Center for Alcohol Research, McKnight Brain Institute, University of Florida, Gainesville, Florida 32611, USA.
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