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Basavarajappa BS, Subbanna S. Synaptic Plasticity Abnormalities in Fetal Alcohol Spectrum Disorders. Cells 2023; 12:442. [PMID: 36766783 PMCID: PMC9913617 DOI: 10.3390/cells12030442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/10/2023] [Accepted: 01/27/2023] [Indexed: 01/31/2023] Open
Abstract
The brain's ability to strengthen or weaken synaptic connections is often termed synaptic plasticity. It has been shown to function in brain remodeling following different types of brain damage (e.g., drugs of abuse, alcohol use disorders, neurodegenerative diseases, and inflammatory conditions). Although synaptic plasticity mechanisms have been extensively studied, how neural plasticity can influence neurobehavioral abnormalities in alcohol use disorders (AUDs) is far from being completely understood. Alcohol use during pregnancy and its harmful effects on the developing offspring are major public health, social, and economic challenges. The significant attribute of prenatal alcohol exposure on offspring is damage to the central nervous system (CNS), causing a range of synaptic structural, functional, and behavioral impairments, collectively called fetal alcohol spectrum disorder (FASD). Although the synaptic mechanisms in FASD are limited, emerging evidence suggests that FASD pathogenesis involves altering a set of molecules involved in neurotransmission, myelination, and neuroinflammation. These studies identify several immediate and long-lasting changes using many molecular approaches that are essential for synaptic plasticity and cognitive function. Therefore, they can offer potential synaptic targets for the many neurobehavioral abnormalities observed in FASD. In this review, we discuss the substantial research progress in different aspects of synaptic and molecular changes that can shed light on the mechanism of synaptic dysfunction in FASD. Increasing our understanding of the synaptic changes in FASD will significantly advance our knowledge and could provide a basis for finding novel therapeutic targets and innovative treatment strategies.
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Affiliation(s)
- Balapal S. Basavarajappa
- Center for Dementia Research, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA
- Molecular Imaging and Neuropathology Area, New York State Psychiatric Institute, New York, NY 10032, USA
- Department of Psychiatry, Columbia University Irving Medical Center, New York, NY 10032, USA
- Department of Psychiatry, New York University Langone Medical Center, New York, NY 10016, USA
| | - Shivakumar Subbanna
- Center for Dementia Research, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA
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Long Term Depression in Rat Hippocampus and the Effect of Ethanol during Fetal Life. Brain Sci 2017; 7:brainsci7120157. [PMID: 29182556 PMCID: PMC5742760 DOI: 10.3390/brainsci7120157] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 11/20/2017] [Accepted: 11/27/2017] [Indexed: 12/11/2022] Open
Abstract
Alcohol (ethanol) disturbs cognitive functions including learning and memory in humans, non-human primates, and laboratory animals such as rodents. As studied in animals, cellular mechanisms for learning and memory include bidirectional synaptic plasticity, long-term potentiation (LTP), and long-term depression (LTD), primarily in the hippocampus. Most of the research in the field of alcohol has analyzed the effects of ethanol on LTP; however, with recent advances in the understanding of the physiological role of LTD in learning and memory, some authors have examined the effects of ethanol exposure on this particular signal. In the present review, I will focus on hippocampal LTD recorded in rodents and the effects of fetal alcohol exposure on this signal. A synthesis of the findings indicates that prenatal ethanol exposure disturbs LTD concurrently with LTP in offspring and that both glutamatergic and γ-aminobutyric acid (GABA) neurotransmissions are altered and contribute to LTD disturbances. Although the ultimate mode of action of ethanol on these two transmitter systems is not yet clear, novel suggestions have recently appeared in the literature.
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Marszalek-Grabska M, Gibula-Bruzda E, Bodzon-Kulakowska A, Suder P, Gawel K, Talarek S, Listos J, Kedzierska E, Danysz W, Kotlinska JH. ADX-47273, a mGlu5 receptor positive allosteric modulator, attenuates deficits in cognitive flexibility induced by withdrawal from 'binge-like' ethanol exposure in rats. Behav Brain Res 2017; 338:9-16. [PMID: 29030082 DOI: 10.1016/j.bbr.2017.10.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 10/01/2017] [Accepted: 10/09/2017] [Indexed: 11/15/2022]
Abstract
Repeated exposure to and withdrawal from ethanol induces deficits in spatial reversal learning. Data indicate that metabotropic glutamate 5 (mGlu5) receptors are implicated in synaptic plasticity and learning and memory. These receptors functionally interact with N-methyl-d-aspartate (NMDA) receptors, and activation of one type results in the activation of the other. We examined whether (S)-(4-fluorophenyl)(3-(3-(4-fluorophenyl)-1,2,4-oxadiazol-5-yl)-piperidin-1-yl (ADX-47273), a positive allosteric modulator (PAM) of mGlu5 receptor, attenuates deficits in reversal learning induced by withdrawal (11-13days) from 'binge-like' ethanol input (5.0g/kg, i.g. for 5days) in the Barnes maze (a spatial learning) task in rats. We additionally examined the effects of ADX-47273 on the expression of the NMDA receptors subunit, GluN2B, in the hippocampus and prefrontal cortex, on the 13th day of ethanol withdrawal. Herein, withdrawal from repeated ethanol administration impaired reversal learning, but not the probe trial. Moreover, ADX-47273 (30mg/kg, i.p.) given prior to the first reversal learning trial for 3days in the Barnes maze, significantly enhanced performance in the ethanol-treated group. The 13th day of ethanol abstinence decreased the expression of the GluN2B subunit in the selected brain regions, but ADX-47273 administration increased it. In conclusion, positive allosteric modulation of mGlu5 receptors recovered spatial reversal learning impairment induced by withdrawal from 'binge-like' ethanol exposure. Such effect seems to be correlated with the mGlu5 receptors mediated potentiation of GluN2B-NMDA receptor mediated responses in the hippocampus and prefrontal cortex. Thus, our results emphasize the role of mGlu5 receptor PAM in the adaptive learning impaired by ethanol exposure.
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Affiliation(s)
| | - Ewa Gibula-Bruzda
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland
| | - Anna Bodzon-Kulakowska
- Department of Biochemistry and Neurobiology, AGH University of Science and Technology, Krakow, Poland
| | - Piotr Suder
- Department of Biochemistry and Neurobiology, AGH University of Science and Technology, Krakow, Poland
| | - Kinga Gawel
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland; Department of Experimental and Clinical Pharmacology, Medical University, Lublin, Poland
| | - Sylwia Talarek
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland
| | - Joanna Listos
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland
| | - Ewa Kedzierska
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland
| | | | - Jolanta H Kotlinska
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland.
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Kraus A, Michalak M. Endoplasmic reticulum quality control and dysmyelination. Biomol Concepts 2015; 2:261-74. [PMID: 25962034 DOI: 10.1515/bmc.2011.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Dysmyelination contributes to several human diseases including multiple sclerosis, Charcot-Marie-Tooth, leukodystrophies, and schizophrenia and can result in serious neurological disability. Properly formed, compacted myelin sheaths are required for appropriate nerve conduction velocities and the health and survival of neurons. Many different molecular mechanisms contribute to dysmyelination and many of these mechanisms originate at the level of the endoplasmic reticulum. The endoplasmic reticulum is a critical organelle for myelin biosynthesis and maintenance as the site of myelin protein folding quality control, Ca2+ homeostasis, cholesterol biosynthesis, and modulation of cellular stress. This review paper highlights the role of the endoplasmic reticulum and its resident molecules as an upstream and dynamic contributor to myelin and myelin pathologies.
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Bird CW, Candelaria-Cook FT, Magcalas CM, Davies S, Valenzuela CF, Savage DD, Hamilton DA. Moderate prenatal alcohol exposure enhances GluN2B containing NMDA receptor binding and ifenprodil sensitivity in rat agranular insular cortex. PLoS One 2015; 10:e0118721. [PMID: 25747876 PMCID: PMC4351952 DOI: 10.1371/journal.pone.0118721] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 01/06/2015] [Indexed: 12/31/2022] Open
Abstract
Prenatal exposure to alcohol affects the expression and function of glutamatergic neurotransmitter receptors in diverse brain regions. The present study was undertaken to fill a current gap in knowledge regarding the regional specificity of ethanol-related alterations in glutamatergic receptors in the frontal cortex. We quantified subregional expression and function of glutamatergic neurotransmitter receptors (AMPARs, NMDARs, GluN2B-containing NMDARs, mGluR1s, and mGluR5s) by radioligand binding in the agranular insular cortex (AID), lateral orbital area (LO), prelimbic cortex (PrL) and primary motor cortex (M1) of adult rats exposed to moderate levels of ethanol during prenatal development. Increased expression of GluN2B-containing NMDARs was observed in AID of ethanol-exposed rats compared to modest reductions in other regions. We subsequently performed slice electrophysiology measurements in a whole-cell patch-clamp preparation to quantify the sensitivity of evoked NMDAR-mediated excitatory postsynaptic currents (EPSCs) in layer II/III pyramidal neurons of AID to the GluN2B negative allosteric modulator ifenprodil. Consistent with increased GluN2B expression, ifenprodil caused a greater reduction in NMDAR-mediated EPSCs from prenatal alcohol-exposed rats than saccharin-exposed control animals. No alterations in AMPAR-mediated EPSCs or the ratio of AMPARs/NMDARs were observed. Together, these data indicate that moderate prenatal alcohol exposure has a significant and lasting impact on GluN2B-containing receptors in AID, which could help to explain ethanol-related alterations in learning and behaviors that depend on this region.
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Affiliation(s)
- Clark W. Bird
- Department of Psychology, University of New Mexico, Albuquerque, New Mexico, United States of America
| | | | - Christy M. Magcalas
- Department of Psychology, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Suzy Davies
- Department of Neurosciences, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - C. Fernando Valenzuela
- Department of Neurosciences, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Daniel D. Savage
- Department of Neurosciences, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Derek A. Hamilton
- Department of Psychology, University of New Mexico, Albuquerque, New Mexico, United States of America
- Department of Neurosciences, University of New Mexico, Albuquerque, New Mexico, United States of America
- * E-mail:
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Investigation into the effects of prenatal alcohol exposure on postnatal spine development and expression of synaptophysin and PSD95 in rat hippocampus. Int J Dev Neurosci 2013; 33:106-14. [DOI: 10.1016/j.ijdevneu.2013.12.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 11/28/2013] [Accepted: 12/12/2013] [Indexed: 01/07/2023] Open
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Alfonso-Loeches S, Guerri C. Molecular and behavioral aspects of the actions of alcohol on the adult and developing brain. Crit Rev Clin Lab Sci 2011; 48:19-47. [PMID: 21657944 DOI: 10.3109/10408363.2011.580567] [Citation(s) in RCA: 180] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The brain is one of the major target organs of alcohol actions. Alcohol abuse can lead to alterations in brain structure and functions and, in some cases, to neurodegeneration. Cognitive deficits and alcohol dependence are highly damaging consequences of alcohol abuse. Clinical and experimental studies have demonstrated that the developing brain is particularly vulnerable to alcohol, and that drinking during gestation can lead to a range of physical, learning and behavioral defects (fetal alcohol spectrum disorders), with the most dramatic presentation corresponding to fetal alcohol syndrome. Recent findings also indicate that adolescence is a stage of brain maturation and that heavy drinking at this stage can have a negative impact on brain structure and functions causing important short- and long-term cognitive and behavioral consequences. The effects of alcohol on the brain are not uniform; some brain areas or cell populations are more vulnerable than others. The prefrontal cortex, the hippocampus, the cerebellum, the white matter and glial cells are particularly susceptible to the effects of ethanol. The molecular actions of alcohol on the brain are complex and involve numerous mechanisms and signaling pathways. Some of the mechanisms involved are common for the adult brain and for the developing brain, while others depend on the developmental stage. During brain ontogeny, alcohol causes irreversible alterations to the brain structure. It also impairs several molecular, neurochemical and cellular events taking place during normal brain development, including alterations in both gene expression regulation and the molecules involved in cell-cell interactions, interference with the mitogenic and growth factor response, enhancement of free radical formation and derangements of glial cell functions. However, in both adult and adolescent brains, alcohol damages specific brain areas through mechanisms involving excitotoxicity, free radical formation and neuroinflammatory damage resulting from activation of the innate immune system mediated by TLR4 receptors. Alcohol also acts on specific membrane proteins, such as neurotransmitter receptors (e.g. NMDA, GABA-A), ion channels (e.g. L-type Ca²⁺ channels, GIRKs), and signaling pathways (e.g. PKA and PKC signaling). These effects might underlie the wide variety of behavioral effects induced by ethanol drinking. The neuroadaptive changes affecting neurotransmission systems which are more sensitive to the acute effects of alcohol occur after long-term alcohol consumption. Alcohol-induced maladaptations in the dopaminergic mesolimbic system, abnormal plastic changes in the reward-related brain areas and genetic and epigenetic factors may all contribute to alcohol reinforcement and alcohol addiction. This manuscript reviews the mechanisms by which ethanol impacts the adult and the developing brain, and causes both neural impairments and cognitive and behavioral dysfunctions. The identification and the understanding of the cellular and molecular mechanisms involved in ethanol toxicity might contribute to the development of treatments and/or therapeutic agents that could reduce or eliminate the deleterious effects of alcohol on the brain.
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Roussotte F, Soderberg L, Sowell E. Structural, metabolic, and functional brain abnormalities as a result of prenatal exposure to drugs of abuse: evidence from neuroimaging. Neuropsychol Rev 2010; 20:376-97. [PMID: 20978945 PMCID: PMC2988996 DOI: 10.1007/s11065-010-9150-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Accepted: 10/06/2010] [Indexed: 12/28/2022]
Abstract
Prenatal exposure to alcohol and stimulants negatively affects the developing trajectory of the central nervous system in many ways. Recent advances in neuroimaging methods have allowed researchers to study the structural, metabolic, and functional abnormalities resulting from prenatal exposure to drugs of abuse in living human subjects. Here we review the neuroimaging literature of prenatal exposure to alcohol, cocaine, and methamphetamine. Neuroimaging studies of prenatal alcohol exposure have reported differences in the structure and metabolism of many brain systems, including in frontal, parietal, and temporal regions, in the cerebellum and basal ganglia, as well as in the white matter tracts that connect these brain regions. Functional imaging studies have identified significant differences in brain activation related to various cognitive domains as a result of prenatal alcohol exposure. The published literature of prenatal exposure to cocaine and methamphetamine is much smaller, but evidence is beginning to emerge suggesting that exposure to stimulant drugs in utero may be particularly toxic to dopamine-rich basal ganglia regions. Although the interpretation of such findings is somewhat limited by the problem of polysubstance abuse and by the difficulty of obtaining precise exposure histories in retrospective studies, such investigations provide important insights into the effects of drugs of abuse on the structure, function, and metabolism of the developing human brain. These insights may ultimately help clinicians develop better diagnostic tools and devise appropriate therapeutic interventions to improve the condition of children with prenatal exposure to drugs of abuse.
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Affiliation(s)
- Florence Roussotte
- Developmental Cognitive Neuroimaging Group, Department of Neurology, University of California, Los Angeles, CA USA
- Interdepartmental Ph.D. Program for Neuroscience, University of California, Los Angeles, CA USA
| | - Lindsay Soderberg
- Developmental Cognitive Neuroimaging Group, Department of Neurology, University of California, Los Angeles, CA USA
| | - Elizabeth Sowell
- Developmental Cognitive Neuroimaging Group, Department of Neurology, University of California, Los Angeles, CA USA
- Interdepartmental Ph.D. Program for Neuroscience, University of California, Los Angeles, CA USA
- Developmental Cognitive Neuroimaging Group, Laboratory of Neuro Imaging, University of California, Los Angeles, 710 Westwood Plaza, Room 1-138, Los Angeles, CA 90095-7332 USA
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Pian JP, Criado JR, Milner R, Ehlers CL. N-methyl-D-aspartate receptor subunit expression in adult and adolescent brain following chronic ethanol exposure. Neuroscience 2010; 170:645-54. [PMID: 20603193 DOI: 10.1016/j.neuroscience.2010.06.065] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Revised: 06/16/2010] [Accepted: 06/25/2010] [Indexed: 11/17/2022]
Abstract
Substantial evidence suggests that glutamatergic neurotransmission is a critical mediator of the experience-dependent synaptic plasticity that may underlie alcohol dependence. Substance abuse typically begins in adolescence; therefore, the impact of alcohol on glutamatergic systems during this critical time in brain development is of particular importance. The N-methyl-d-aspartate receptor (NMDAR) is involved in developmental mechanisms underlying neuronal differentiation and synaptogenesis and as such may be a target system for alcohol effects during adolescence. In the present study quantitative biochemical determinations were made of the relative abundance of different protein expressions of NMDAR subunits in adolescents and adults after 2 weeks of ethanol vapor exposure, and 24 h and 2 weeks following withdrawal. After 2 weeks of ethanol vapor exposure N-methyl-d-aspartate receptor NR1 subunit (NR1), N-methyl-d-aspartate receptor NR2A subunit (NR2A), and N-methyl-d-aspartate receptor NR2B subunit (NR2B) subunit expression was found to be increased in hippocampus of the adults. In contrast, 2 weeks of ethanol exposure resulted in no significant changes in NR1 and NR2B subunits and a reduction NR2A subunit expression in hippocampus in adolescents. Twenty-four h and 2 weeks following withdrawal from ethanol vapor NR1 and NR2A subunit expression in hippocampus was decreased in adolescents, whereas in adults it had returned to control levels. In frontal cortex, 2 weeks of chronic ethanol exposure produced decreases in NR1 subunit expression in both adults and adolescents but also produced decreases in NR2A and NR2B subunit expression in adults that returned or exceeded control levels by 2 weeks following withdrawal from ethanol vapor. These results demonstrate that NMDAR subunit composition can be modulated differentially between adolescents and adults by chronic ethanol exposure and withdrawal. These developmental differences in NMDAR subunits composition may also be associated with the enhanced vulnerability of the adolescent brain to ethanol dependence.
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Affiliation(s)
- J P Pian
- Department of Molecular and Integrative Neurosciences, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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Samudio-Ruiz SL, Allan AM, Sheema S, Caldwell KK. Hippocampal N-methyl-D-aspartate receptor subunit expression profiles in a mouse model of prenatal alcohol exposure. Alcohol Clin Exp Res 2009; 34:342-53. [PMID: 19951292 DOI: 10.1111/j.1530-0277.2009.01096.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND Although several reports have been published showing prenatal ethanol exposure is associated with alterations in N-methyl-D-aspartate (NMDA) receptor subunit levels and, in a few cases, subcellular distribution, results of these studies are conflicting. METHODS We used semi-quantitative immunoblotting techniques to analyze NMDA receptor NR1, NR2A, and NR2B subunit levels in the adult mouse hippocampal formation isolated from offspring of dams who consumed moderate amounts of ethanol throughout pregnancy. We employed subcellular fractionation and immunoprecipitation techniques to isolate synaptosomal membrane- and postsynaptic density protein-95 (PSD-95)-associated pools of receptor subunits. RESULTS We found that, compared to control animals, fetal alcohol-exposed (FAE) adult mice had: (i) increased synaptosomal membrane NR1 levels with no change in association of this subunit with PSD-95 and no difference in total NR1 expression in tissue homogenates; (ii) decreased NR2A subunit levels in hippocampal homogenates, but no alterations in synaptosomal membrane NR2A levels and no change in NR2A-PSD-95 association; and (iii) no change in tissue homogenate or synaptosomal membrane NR2B levels but a reduction in PSD-95-associated NR2B subunits. No alterations were found in mRNA levels of NMDA receptor subunits suggesting that prenatal alcohol-associated differences in subunit protein levels are the result of differences in post-transcriptional regulation of subunit localization. CONCLUSIONS Our results demonstrate that prenatal alcohol exposure induces selective changes in NMDA receptor subunit levels in specific subcellular locations in the adult mouse hippocampal formation. Of particular interest is the finding of decreased PSD-95-associated NR2B levels, suggesting that synaptic NR2B-containing NMDA receptor concentrations are reduced in FAE animals. This result is consistent with various biochemical, physiological, and behavioral findings that have been linked with prenatal alcohol exposure.
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Affiliation(s)
- Sabrina L Samudio-Ruiz
- Department of Neurosciences, School of Medicine, University of New Mexico, Albuquerque, New Mexico, USA
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Thompson BL, Levitt P, Stanwood GD. Prenatal exposure to drugs: effects on brain development and implications for policy and education. Nat Rev Neurosci 2009; 10:303-12. [PMID: 19277053 PMCID: PMC2777887 DOI: 10.1038/nrn2598] [Citation(s) in RCA: 239] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The effects of prenatal exposure to drugs on brain development are complex and are modulated by the timing, dose and route of drug exposure. It is difficult to assess these effects in clinical cohorts as these are beset with problems such as multiple exposures and difficulties in documenting use patterns. This can lead to misinterpretation of research findings by the general public, the media and policy makers, who may mistakenly assume that the legal status of a drug correlates with its biological impact on fetal brain development and long-term clinical outcomes. It is important to close the gap between what science tells us about the impact of prenatal drug exposure on the fetus and the mother and what we do programmatically with regard to at-risk populations.
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Affiliation(s)
- Barbara L Thompson
- Department of Pharmacology, Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN 37232, USA
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Chang YC, Kuo YM, Huang AM, Huang CC. Repetitive febrile seizures in rat pups cause long-lasting deficits in synaptic plasticity and NR2A tyrosine phosphorylation. Neurobiol Dis 2005; 18:466-75. [PMID: 15755673 DOI: 10.1016/j.nbd.2004.12.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2004] [Revised: 11/24/2004] [Accepted: 12/22/2004] [Indexed: 11/15/2022] Open
Abstract
Adult rats with early-life frequently repetitive febrile seizures (FRFS), but not single febrile seizure (SFS), exhibited impaired performance in inhibitory avoidance tasks but without significant hippocampal neuronal loss. The mechanisms of long-term memory impairment in the hippocampus of adult rats with early-life FRFS remain unknown. Using a heated-air febrile seizures (FS) paradigm, male rat pups were subjected to single or nine episodes of brief FS at days 10 to 12 postpartum. We found that early-life FRFS led to long-term bidirectional modulation in hippocampal synaptic plasticity, i.e., impaired long-term potentiation and facilitated long-term depression. Three hours after inhibitory avoidance training, phosphorylation of hippocampal extracellular signal-regulated kinase (ERK) 1/2 was significantly less in the FRFS group than in controls. Furthermore, there was a selective alteration in NMDA receptor-mediated ERK1/2 phosphorylation in the hippocampus of the FRFS group. Although the expression levels of NMDA receptor subunits and interaction of NMDA receptor and postsynaptic density 95 did not alter quantitatively, there was a specific alteration in NR2A, but not NR2B, subunit tyrosine phosphorylation after NMDA stimulation in the FRFS group. These data offer a potential molecular explanation for the hippocampus-dependent memory deficits observed in the rats with early-life FRFS.
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Affiliation(s)
- Ying-Chao Chang
- Department of Pediatrics, Chang Gung Memorial Hospital, Kaohsiung, Taiwan
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Honse Y, Randall PK, Leslie SW. Prenatal ethanol exposure modifies [3H]MK-801 binding to NMDA receptors: spermidine and ifenprodil. Alcohol Clin Exp Res 2004; 27:1993-2001. [PMID: 14691388 DOI: 10.1097/01.alc.0000099029.55026.c6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND It has been suggested that abnormalities seen in fetal alcohol syndrome are linked with NMDA receptor malfunction. Our laboratory has previously shown that prenatal ethanol treatment decreases [3H]MK-801 binding density at postnatal day 21, when NMDA receptor subunit protein levels were unaltered. Thus, the focus of the present study was to examine whether prenatal ethanol modifies native NMDA receptor levels. METHODS Cerebral cortices were taken from offspring born to three treatment groups of pregnant Sprague Dawley(R) rats: an ethanol group given an ethanol liquid diet during the gestational period, a pair-fed control group that received a liquid diet without ethanol, and an ad libitum group fed rat chow and tap water. Western blot studies were carried out at postnatal days 1, 7, 14, and 21 to examine total protein expression of NR1 and NR1b splice variants. NR2 subunit levels were examined by [3H]MK-801 binding studies using spermidine, an endogenous polyamine, and ifenprodil, a selective NR2B antagonist. RESULTS [3H]MK-801 binding density was significantly reduced in prenatal ethanol-treated groups compared with ad libitum and pair-fed control groups. Spermidine increased [3H]MK-801 binding, although potentiation by spermidine was not significantly different among all three experimental groups. Furthermore, no significant differences in total protein expression of NR1 or NR1b splice variants were observed in cortical membrane homogenates at postnatal days 1 through 21. [3H]MK-801 binding in the presence of ifenprodil showed that prenatal ethanol treatment significantly decreased low-affinity ifenprodil binding. High-affinity ifenprodil binding was reduced in both pair-fed and ethanol-treated groups. CONCLUSIONS These results suggest that prenatal ethanol treatment reduces [3H]MK-801 binding and that this reduction may be due to a decrease in NR2A subunits.
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Affiliation(s)
- Yumiko Honse
- Division of Pharmacology and Toxicology, College of Pharmacy and Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, USA.
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Papadakis M, Hawkins LM, Stephenson FA. Appropriate NR1-NR1 Disulfide-linked Homodimer Formation Is Requisite for Efficient Expression of Functional, Cell Surface N-Methyl-D-aspartate NR1/NR2 Receptors. J Biol Chem 2004; 279:14703-12. [PMID: 14732708 DOI: 10.1074/jbc.m313446200] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A c-Myc epitope-tagged N-methyl-D-aspartate receptor NR1-2a subunit was generated, NR1-2a(c-Myc), where the tag was inserted after amino acid 81. NR1-2a(c-Myc) /NR2A receptors when expressed in mammalian cells are not trafficked to the cell surface nor do they yield cell cytotoxicity post-transfection. NR1-2a(c-Myc) was, however, shown to assemble with NR2A subunits by immunoprecipitation and [(3)H]MK801 radioligand binding assays. Immunoblots of cells co-transfected with wild-type NR1-2a/NR2A subunits yielded two NR1-2a immunoreactive species with molecular masses of 115 and 226 kDa. Two-dimensional electrophoresis under non-reducing and reducing conditions revealed that the 226-kDa band contained disulfide-linked NR1-2a subunits. Only the 115-kDa NR1-2a species was detected for NR1-2a(c-Myc)/NR2A. The c-Myc epitope is inserted adjacent to cysteine 79 of the NR1-2a subunit; therefore, it is possible that the tag may prevent the formation of NR1 disulfide bridges. A series of cysteine --> alanine NR1-2a mutants was generated, and the NR1-2a mutants were co-expressed with NR2A or NR2B subunits in mammalian cells and characterized with respect to cell surface expression, cell cytotoxicity post-transfection, co-association by immunoprecipitation, and immunoblotting following SDS-PAGE under both reducing and non-reducing conditions. When co-expressed with NR2A in mammalian cells, NR1-2a(C79A)/NR2A displayed similar properties to NR1-2a(c-Myc)/NR2A in that the 226-kDa NR1 immunoreactive species was not detectable, and trafficking to the cell surface was impaired compared with wild-type NR1/NR2 receptors. These results provide the first biochemical evidence for the formation of NR1-NR1 intersubunit disulfide-linked homodimers involving cysteine 79. They suggest that disulfide bridging and structural integrity within the NR1 N-terminal domain is requisite for cell surface N-methyl-D-aspartate receptor expression.
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Affiliation(s)
- Michalis Papadakis
- Department of Pharmaceutical and Biological Chemistry, School of Pharmacy, University of London, 29/39 Brunswick Square, London WC1N 1AX, United Kingdom
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Nixon K, Hughes PD, Amsel A, Leslie SW. NMDA receptor subunit expression after combined prenatal and postnatal exposure to ethanol. Alcohol Clin Exp Res 2004; 28:105-12. [PMID: 14745308 DOI: 10.1097/01.alc.0000106311.88523.7b] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The N-methyl-D-aspartate receptor (NMDAR), a subtype of glutamate receptor, is essential for normal neurodevelopment. The brain growth spurt, which is both prenatal and postnatal in the rat, is a time when the brain is especially sensitive to the effects of a teratogen, such as alcohol. Changes in NMDAR function after early perinatal exposure to ethanol (EtOH) may be related to alterations in the expression of secondary subunits. Thus, we investigated the expression of the NR1, NR2A, and NR2B subunits after combined prenatal and postnatal exposure to EtOH. METHODS A binge model was used to administer EtOH (5 g/kg) or isocaloric vehicle to pregnant female rats followed by EtOH (6.2 g/kg) or isocaloric control diet from postnatal days 4 through 9 via an artificial rearing method. Proteins from crude membrane homogenates isolated from cortex and hippocampus at postnatal day 10, 14, or 21 were separated in a standard Western blot procedure. RESULTS The expression of the NR2A subunit of EtOH-exposed pups showed a significant increase at postnatal day 10 in hippocampus compared with diet controls. No significant changes were seen for any other subunit in either region. CONCLUSIONS The up-regulation of NR2A during EtOH withdrawal is consistent with compensatory changes to prolonged inhibition of the NMDAR. These results indicate that postnatal exposure to ethanol produces distinct effects on the NMDAR, which may underlie deficits associated with alcohol-related neurodevelopmental disorder.
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Affiliation(s)
- Kimberly Nixon
- Department of Psychology, Waggoner Center for Alcohol and Addiciton Research, University of Texas, Austin, Texas, USA.
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Cannizzaro C, D'Amico M, Altobelli D, Preziosi P, Martire M. Neurosteroid modulation of the presynaptic NMDA receptors regulating hippocampal noradrenaline release in normal rats and those exposed prenatally to diazepam. Neurochem Int 2003; 43:121-7. [PMID: 12620280 DOI: 10.1016/s0197-0186(02)00226-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Prenatal exposure to diazepam (DZ), a positive allosteric modulator of the gamma-aminobutyric acid(A) (GABA(A)) receptor complex, exerts profound effects that become more evident during puberty and in many cases are sex-specific, suggesting that such exposure interferes with the activity of steroid hormones. Apart from their well known effects on the genome, the reduced metabolites of many steroid hormones also interact directly with membrane receptors, including those for N-methyl-D-aspartate (NMDA). In this study, we compared the effects of several neurosteroids on NMDA receptors from normal rats and those exposed in utero to DZ (1.25mg/kg per day) from the 14th through the 20th day of gestation. In superfused rat hippocampal synaptosomes, activation of the NMDA receptor stimulates the basal release of [3H]noradrenaline ([3H]NA), which was used in our study as an index of receptor function. [3H]NA release was evoked in a concentration-dependent manner by NMDA (100 microM) plus glycine (GLY). The maximal increase (68.23+/-3.86%) with respect to basal release was achieved with a GLY concentration of 10 microM, and the EC(50) for GLY was 0.1 microM. Release stimulated by 100 microM NMDA + 0.1 microM GLY was not modified by any of the neurosteroids tested, with the exception of pregnenolone sulfate (PREG-S), which produced a 78.57+/-3.94% reduction in release at the maximal concentration used (0.3 microM). In synaptosomes from animals exposed in utero to DZ, the inhibitory effect of PREG-S was reduced by 46.55+/-2.33%. Given the important roles played by NMDA receptors in physiological and pathological processes within the central nervous system (CNS), characterization of NMDA receptor modulation is an important objective. The fact that this modulation can be altered by exposure in utero to DZ indicates that the behavioral abnormalities observed in exposed animals might be partially attributed to an altered sensitivity of NMDA receptors to the modulatory effects of neurosteroids.
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Affiliation(s)
- Carla Cannizzaro
- Institute of Pharmacology, Hospital P. Giaccone, University of Palermo, Palermo, Italy
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Webb B, Walker DW, Heaton MB. Nerve growth factor and chronic ethanol treatment alter calcium homeostasis in developing rat septal neurons. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2003; 143:57-71. [PMID: 12763581 DOI: 10.1016/s0165-3806(03)00100-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Chronic ethanol treatment (CET) during development produces cellular adaptations resulting in tolerance to the acute effects of ethanol (EtOH). The objectives of this study were to determine whether CET during the prenatal period (PCET) followed by a period of in vitro CET (PCET-CET) altered intracellular calcium [Ca(2+)](i) and produced tolerance to acute EtOH treatment (AET), and whether nerve growth factor (NGF) modulated the effects of PCET-CET in cultured developing rat septal neurons. Fetuses were obtained from EtOH-fed and sucrose-fed (diet-control) female rats. Neurons from PCET fetuses were cultured in the presence of NGF (+NGF) and 200 mg/dl (mg %) EtOH and diet-control cultures received NGF and no EtOH. PCET and diet-control cultures were then divided into two groups, +NGF and -NGF (withdrawn from NGF), and exposed acutely to one of five doses of EtOH during stimulation with potassium (K(+)) chloride. [Ca(2+)](i) was measured using fura-2. PCET-CET did not affect resting [Ca(2+)](i). PCET-CET decreased and acute EtOH withdrawal increased overall K(+)-stimulated changes in [Ca(2+)](i), but only in +NGF PCET neurons. Reducing the level of EtOH from 200 to 100 mg % decreased overall K(+)-stimulated [Ca(2+)](i) in -NGF PCET neurons. The effects of PCET-CET or PCET-CET combined with NGF on overall K(+)-stimulated changes in [Ca(2+)](i) occurred mostly in the early and middle phases of the K(+)-response. NGF reduced overall K(+)-stimulated changes in [Ca(2+)](i) in PCET neurons during EtOH withdrawal and during AET with 200 mg % EtOH and increased overall K(+)-stimulated changes in [Ca(2+)](i) during AET with 400 and 800 mg % EtOH. There was no effect of NGF on overall K(+)-stimulated changes in [Ca(2+)](i) in diet-control neurons with the exception that NGF-treatment decreased overall K(+)-stimulated changes in [Ca(2+)](i) during AET with 400 mg % EtOH. The effects of AET on overall K(+)-stimulated changes in [Ca(2+)](i) mostly occurred in +NGF PCET neurons. In conclusion, CET during development of the brain could adversely affect Ca(2+)-dependent functions such as neuronal migration, neurite outgrowth, and synaptogenesis in neurons even in the presence of neurotrophin support.
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Affiliation(s)
- Barbara Webb
- Department of Neuroscience, Center for Alcohol Research, Gainesville, FL, USA
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