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Dalton VS, Kolshus E, McLoughlin DM. Epigenetics and depression: return of the repressed. J Affect Disord 2014; 155:1-12. [PMID: 24238955 DOI: 10.1016/j.jad.2013.10.028] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 10/15/2013] [Accepted: 10/16/2013] [Indexed: 10/26/2022]
Abstract
INTRODUCTION Epigenetics has recently emerged as a potential mechanism by which adverse environmental stimuli can result in persistent changes in gene expression. Epigenetic mechanisms function alongside the DNA sequence to modulate gene expression and ultimately influence protein production. The current review provides an introduction and overview of epigenetics with a particular focus on preclinical and clinical studies relevant to major depressive disorder (MDD). METHODS PubMed and Web of Science databases were interrogated from January 1995 up to December 2012 using combinations of search terms, including "epigenetic", "microRNA" and "DNA methylation" cross referenced with "depression", "early life stress" and "antidepressant". RESULTS There is an association between adverse environmental stimuli, such as early life stress, and epigenetic modification of gene expression. Epigenetic changes have been reported in humans with MDD and may serve as biomarkers to improve diagnosis. Antidepressant treatments appear to reverse or initiate compensatory epigenetic alterations that may be relevant to their mechanism of action. LIMITATIONS As a narrative review, the current report was interpretive and qualitative in nature. CONCLUSION Epigenetic modification of gene expression provides a mechanism for understanding the link between long-term effects of adverse life events and the changes in gene expression that are associated with depression. Although still a developing field, in the future, epigenetic modifications of gene expression may provide novel biomarkers to predict future susceptibility and/or onset of MDD, improve diagnosis, and aid in the development of epigenetics-based therapies for depression.
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Affiliation(s)
- Victoria S Dalton
- Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland; Department of Psychiatry, Trinity College Dublin, St. Patrick's University Hospital, James's Street, Dublin 8, Ireland
| | - Erik Kolshus
- Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland; Department of Psychiatry, Trinity College Dublin, St. Patrick's University Hospital, James's Street, Dublin 8, Ireland
| | - Declan M McLoughlin
- Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland; Department of Psychiatry, Trinity College Dublin, St. Patrick's University Hospital, James's Street, Dublin 8, Ireland.
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Korgan AC, Green AD, Perrot TS, Esser MJ. Limbic system activation is affected by prenatal predator exposure and postnatal environmental enrichment and further moderated by dam and sex. Behav Brain Res 2013; 259:106-18. [PMID: 24185030 DOI: 10.1016/j.bbr.2013.10.037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 10/18/2013] [Accepted: 10/24/2013] [Indexed: 02/07/2023]
Abstract
Epilepsy is a relatively common and chronic neurological condition, affecting 1-2% of the population. However, understanding of the underlying pathophysiology remains incomplete. To identify potential factors in the early environment that may increase the risk for experiencing seizures, maternal stress and environmental enrichment (EE) were utilized. Pregnant Long-Evans rats were exposed to an ethologically relevant predator stress (PS) and maternal glucocorticoid (GC) response was assessed across the exposure period. At birth, litters were divided into standard care (SC) and EE groups until postnatal day 14 (PD14) when a model of febrile convulsions was used to determine seizure susceptibility of the various groups. Pup brains were then processed for immunohistochemical detection of FosB from several structures in the limbic system as a measure of neuronal activation. Maternal PS-induced GC levels were elevated early in the exposure period, and pup birth weights, in both sexes, were lower in litters from dams exposed to PS. Seizure scores at PD14 were highly individualized and litter dependent, suggesting a dam-dependent and variable effect of controlled pre- and postnatal environmental factors. Further, analysis of FosB-immunoreactive (-ir) patterns revealed an activity dependent distribution, reflecting individual seizure susceptibility. EE had a varying effect on FosB-ir that was dependent on region. In the hippocampus FosB-ir levels were greater in the EE groups while extra-hippocampal regions showed lower levels of FosB-ir. Our results support the concept that pre- and postnatal environmental influences affect fetal programming and neurodevelopment of processes that could underlie seizure susceptibility, but that the magnitude of these effects appears to be dam- or litter-dependent.
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Affiliation(s)
- Austin C Korgan
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada
| | - Amanda D Green
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada
| | - Tara S Perrot
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada.
| | - Michael J Esser
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada; Departments of Pediatrics and Pharmacology, IWK Health Care Centre, Halifax, NS, Canada
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Mychasiuk R, Gibb R, Kolb B. Visualizing the effects of a positive early experience, tactile stimulation, on dendritic morphology and synaptic connectivity with Golgi-cox staining. J Vis Exp 2013:e50694. [PMID: 24121525 PMCID: PMC3935738 DOI: 10.3791/50694] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
To generate longer-term changes in behavior, experiences must be producing stable changes in neuronal morphology and synaptic connectivity. Tactile stimulation is a positive early experience that mimics maternal licking and grooming in the rat. Exposing rat pups to this positive experience can be completed easily and cost-effectively by using highly accessible materials such as a household duster. Using a cross-litter design, pups are either stroked or left undisturbed, for 15 min, three times per day throughout the perinatal period. To measure the neuroplastic changes related to this positive early experience, Golgi-Cox staining of brain tissue is utilized. Owing to the fact that Golgi-Cox impregnation stains a discrete number of neurons rather than all of the cells, staining of the rodent brain with Golgi-Cox solution permits the visualization of entire neuronal elements, including the cell body, dendrites, axons, and dendritic spines. The staining procedure is carried out over several days and requires that the researcher pay close attention to detail. However, once staining is completed, the entire brain has been impregnated and can be preserved indefinitely for ongoing analysis. Therefore, Golgi-Cox staining is a valuable resource for studying experience-dependent plasticity.
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Appleton AA, Armstrong DA, Lesseur C, Lee J, Padbury JF, Lester BM, Marsit CJ. Patterning in placental 11-B hydroxysteroid dehydrogenase methylation according to prenatal socioeconomic adversity. PLoS One 2013; 8:e74691. [PMID: 24040322 PMCID: PMC3764127 DOI: 10.1371/journal.pone.0074691] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 08/07/2013] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Prenatal socioeconomic adversity as an intrauterine exposure is associated with a range of perinatal outcomes although the explanatory mechanisms are not well understood. The development of the fetus can be shaped by the intrauterine environment through alterations in the function of the placenta. In the placenta, the HSD11B2 gene encodes the 11-beta hydroxysteroid dehydrogenase enzyme, which is responsible for the inactivation of maternal cortisol thereby protecting the developing fetus from this exposure. This gene is regulated by DNA methylation, and this methylation and the expression it controls has been shown to be susceptible to a variety of stressors from the maternal environment. The association of prenatal socioeconomic adversity and placental HSD11B2 methylation has not been examined. Following a developmental origins of disease framework, prenatal socioeconomic adversity may alter fetal response to the postnatal environment through functional epigenetic alterations in the placenta. Therefore, we hypothesized that prenatal socioeconomic adversity would be associated with less HSD11B2 methylation. METHODS AND FINDINGS We examined the association between DNA methylation of the HSD11B2 promoter region in the placenta of 444 healthy term newborn infants and several markers of prenatal socioeconomic adversity: maternal education, poverty, dwelling crowding, tobacco use and cumulative risk. We also examined whether such associations were sex-specific. We found that infants whose mothers experienced the greatest levels of socioeconomic adversity during pregnancy had the lowest extent of placental HSD11B2 methylation, particularly for males. Associations were maintained for maternal education when adjusting for confounders (p<0.05). CONCLUSIONS Patterns of HSD11B2 methylation suggest that environmental cues transmitted from the mother during gestation may program the developing fetus's response to an adverse postnatal environment, potentially via less exposure to cortisol during development. Less methylation of placental HSD11B2 may therefore be adaptive and promote the effective management of stress associated with social adversity in a postnatal environment.
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Affiliation(s)
- Allison A. Appleton
- Department of Community and Family Medicine, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - David A. Armstrong
- Department of Pharmacology and Toxicology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Corina Lesseur
- Department of Pharmacology and Toxicology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Joyce Lee
- Department of Pediatrics, Women and Infants Hospital, Providence, Rhode Island, United States of America
- Brown Center for the Study of Children at Risk, Women and Infants Hospital, Providence, Rhode Island, United States of America
| | - James F. Padbury
- Department of Pediatrics, Women and Infants Hospital, Providence, Rhode Island, United States of America
| | - Barry M. Lester
- Department of Pediatrics, Women and Infants Hospital, Providence, Rhode Island, United States of America
- Brown Center for the Study of Children at Risk, Women and Infants Hospital, Providence, Rhode Island, United States of America
| | - Carmen J. Marsit
- Department of Community and Family Medicine, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
- Department of Pharmacology and Toxicology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
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Staples MC, Rosenberg MJ, Allen NA, Porch MW, Savage DD. Impact of combined prenatal ethanol and prenatal stress exposure on anxiety and hippocampal-sensitive learning in adult offspring. Alcohol Clin Exp Res 2013; 37:2039-47. [PMID: 23915215 DOI: 10.1111/acer.12190] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 04/15/2013] [Indexed: 01/16/2023]
Abstract
BACKGROUND Prenatal ethanol (EtOH) and prenatal stress have both been independently shown to induce learning deficits and anxiety behavior in adult offspring. However, the interactive effects of these 2 developmental teratogens on behavioral outcomes have not been systematically evaluated. METHODS We combined an established moderate prenatal EtOH consumption paradigm where Long-Evans rat dams voluntarily consume either a 0 or 5% EtOH solution in 0.066% saccharin water (resulting in a mean peak maternal serum EtOH concentration of 84 mg/dl) with a novel prenatal stress paradigm. Pregnant rats were exposed to 3% 2,3,5-trimethyl-3-thiazoline (TMT) for 20 minutes a day on gestational days 13, 15, 17, and 19. Adult female offspring were evaluated for anxiety-like behavior using an elevated plus-maze and hippocampal-sensitive learning using a 2-trial trace conditioning (TTTC) task. RESULTS TMT exposure produced a threefold increase in maternal serum corticosterone compared to nonexposed, unhandled controls. Neither prenatal exposure paradigm, either alone or in combination, altered maternal weight gain, EtOH consumption, maternal care of litters, litter size, pup birth weight, or pup weight gain up to weaning. Offspring exposed to prenatal stress displayed significant increases in anxiety-like behavior in the elevated plus maze in terms of open arm entries and time spent on the open arms, with no significant effect of prenatal EtOH exposure and no interaction of the 2 prenatal exposures. Performance in a TTTC task revealed a significant effect of prenatal EtOH exposure on freezing behavior on the testing day, with no significant effect of prenatal stress exposure and no interaction of the 2 prenatal exposures. CONCLUSIONS While each prenatal exposure independently produced different behavioral outcomes, the results indicate that there is no significant interaction of prenatal EtOH and prenatal stress exposures on learning or anxiety at the exposure levels employed in this dual exposure paradigm. Subsequent studies will examine whether similar outcomes occur in male offspring and whether other measures of anxiety or learning are differentially impacted by these prenatal exposure paradigms.
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Affiliation(s)
- Miranda C Staples
- Department of Neurosciences , University of New Mexico Health Sciences Center, Albuquerque, New Mexico
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56
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Mychasiuk R, Harker A, Ilnytskyy S, Gibb R. Paternal stress prior to conception alters DNA methylation and behaviour of developing rat offspring. Neuroscience 2013; 241:100-5. [PMID: 23531434 DOI: 10.1016/j.neuroscience.2013.03.025] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 03/08/2013] [Accepted: 03/09/2013] [Indexed: 01/28/2023]
Abstract
Although there has been an abundance of research focused on offspring outcomes associated with maternal experiences, there has been limited examination of the relationship between paternal experiences and offspring brain development. As spermatogenesis is a continuous process, experiences that have the ability to alter epigenetic regulation in fathers may actually change developmental trajectories of offspring. The purpose of this study was to examine the effects of paternal stress prior to conception on behaviour and the epigenome of both male and female developing rat offspring. Male Long-Evans rats were stressed for 27 consecutive days and then mated with control female rats. Early behaviour was tested in offspring using the negative geotaxis task and the open field. At P21 offspring were sacrificed and global DNA methylation levels in the hippocampus and frontal cortex were analysed. Paternal stress prior to conception altered behaviour of all offspring on the negative geotaxis task, delaying acquisition of the task. In addition, male offspring demonstrated a reduction in stress reactivity in the open field paradigm spending more time than expected in the centre of the open field. Paternal stress also altered DNA methylation patterns in offspring at P21, global methylation was reduced in the frontal cortex of female offspring, but increased in the hippocampus of both male and female offspring. The results from this study clearly demonstrate that paternal stress during spermatogenesis can influence offspring behaviour and DNA methylation patterns, and these affects occur in a sex-dependent manner. Development takes place in the centre of a complex interaction between maternal, paternal, and environmental influences, which combine to produce the various phenotypes and individual differences that we perceive.
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Affiliation(s)
- R Mychasiuk
- University of Lethbridge, Lethbridge, AB, Canada.
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57
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Abstract
The developing normal brain shows a remarkable capacity for plastic change in response to a wide range of experiences including sensory and motor experience, psychoactive drugs, parent-child relationships, peer relationships, stress, gonadal hormones, intestinal flora, diet, and injury. The effects of injury vary with the precise age-at-injury, with the general result being that injury during cell migration and neuronal maturation has a poor functional outcome, whereas similar injury during synaptogenesis has a far better outcome. A variety of factors influence functional outcome including the nature of the behavior in question and the age at behavioral assessment as well as pre- and postinjury experiences. Here, we review the phases of brain development, how factors influence brain, and behavioral development in both the normal and perturbed brain, and propose mechanisms that may underlie these effects.
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Affiliation(s)
- Bryan Kolb
- Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Lethbridge, AB, Canada.
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58
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Billack B, Serio R, Silva I, Kinsley CH. Epigenetic changes brought about by perinatal stressors: A brief review of the literature. J Pharmacol Toxicol Methods 2012; 66:221-31. [DOI: 10.1016/j.vascn.2012.08.169] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 07/25/2012] [Accepted: 08/28/2012] [Indexed: 12/27/2022]
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Kolb B, Mychasiuk R, Muhammad A, Li Y, Frost DO, Gibb R. Experience and the developing prefrontal cortex. Proc Natl Acad Sci U S A 2012; 109 Suppl 2:17186-93. [PMID: 23045653 PMCID: PMC3477383 DOI: 10.1073/pnas.1121251109] [Citation(s) in RCA: 330] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The prefrontal cortex (PFC) receives input from all other cortical regions and functions to plan and direct motor, cognitive, affective, and social behavior across time. It has a prolonged development, which allows the acquisition of complex cognitive abilities through experience but makes it susceptible to factors that can lead to abnormal functioning, which is often manifested in neuropsychiatric disorders. When the PFC is exposed to different environmental events during development, such as sensory stimuli, stress, drugs, hormones, and social experiences (including both parental and peer interactions), the developing PFC may develop in different ways. The goal of the current review is to illustrate how the circuitry of the developing PFC can be sculpted by a wide range of pre- and postnatal factors. We begin with an overview of prefrontal functioning and development, and we conclude with a consideration of how early experiences influence prefrontal development and behavior.
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Affiliation(s)
- Bryan Kolb
- Department of Neuroscience, Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Lethbridge, AB, Canada.
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60
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Glover V, Hill J. Sex differences in the programming effects of prenatal stress on psychopathology and stress responses: an evolutionary perspective. Physiol Behav 2012; 106:736-40. [PMID: 22353310 DOI: 10.1016/j.physbeh.2012.02.011] [Citation(s) in RCA: 142] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 01/18/2012] [Accepted: 02/07/2012] [Indexed: 12/12/2022]
Abstract
There is strong evidence from animal studies that prenatal stress has different effects on male and female offspring. In general, although not always, prenatal stress increases anxiety, depression and stress responses, both hypothalamic-pituitary-adrenal and cardiovascular, in female offspring rather than in male. Males are more likely to show learning and memory deficits. There have been few studies so far in humans which differentiate effects of prenatal stress on male and female psychopathology. Some studies support the animal models, but the evidence is inconsistent. The mediating mechanisms for any sex specific effects are little understood, but there is evidence that placental function can differ depending on the sex of the fetus. We suggest that there may be an evolutionary reason for any sex differences in the long term effects of prenatal stress. In a stressful environment it may be adaptive for females, who are more likely to stay in one place and look after children, to be more vigilant, alert to danger and thus show more stress responsiveness. This can give rise to a more anxious or depressed phenotype. With males it may be more adaptive to go out and explore new environments, compete with other males, and be more aggressive. For this it may help to be less responsive to external stressors. More research is needed into sex differences in the effects of prenatal stress in humans, to test these ideas.
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Affiliation(s)
- Vivette Glover
- Institute of Reproductive and Developmental Biology, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, UK.
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61
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Zucchi FCR, Yao Y, Metz GA. The secret language of destiny: stress imprinting and transgenerational origins of disease. Front Genet 2012; 3:96. [PMID: 22675331 PMCID: PMC3366387 DOI: 10.3389/fgene.2012.00096] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 05/10/2012] [Indexed: 12/24/2022] Open
Abstract
Epigenetic regulation modulates gene expression without altering the DNA sequence to facilitate rapid adjustments to dynamically changing environmental conditions. The formation of an epigenetic memory allows passing on this information to subsequent generations. Here we propose that epigenetic memories formed by adverse environmental conditions and stress represent a critical determinant of health and disease in the F3 generation and beyond. Transgenerational programming of epigenetic regulation may represent a key to understand adult-onset complex disease pathogenesis and cumulative effects of life span and familial disease etiology. Ultimately, the mechanisms of generating an epigenetic memory may become of potentially promising diagnostic and therapeutic relevance due to their reversible nature. Exploring the role of environmental factors, such as stress, in causing variations in epigenetic profiles may lead to new avenues of personalized, preventive medicine based on epigenetic signatures and interventions.
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Affiliation(s)
- Fabiola C R Zucchi
- Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Lethbridge, AB, Canada
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Chen A, Kelley LD, Janušonis S. Effects of prenatal stress and monoaminergic perturbations on the expression of serotonin 5-HT4 and adrenergic β2 receptors in the embryonic mouse telencephalon. Brain Res 2012; 1459:27-34. [DOI: 10.1016/j.brainres.2012.04.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Revised: 03/21/2012] [Accepted: 04/11/2012] [Indexed: 12/13/2022]
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Fetal stress and programming of hypoxic/ischemic-sensitive phenotype in the neonatal brain: mechanisms and possible interventions. Prog Neurobiol 2012; 98:145-65. [PMID: 22627492 DOI: 10.1016/j.pneurobio.2012.05.010] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 05/10/2012] [Accepted: 05/11/2012] [Indexed: 12/12/2022]
Abstract
Growing evidence of epidemiological, clinical and experimental studies has clearly shown a close link between adverse in utero environment and the increased risk of neurological, psychological and psychiatric disorders in later life. Fetal stresses, such as hypoxia, malnutrition, and fetal exposure to nicotine, alcohol, cocaine and glucocorticoids may directly or indirectly act at cellular and molecular levels to alter the brain development and result in programming of heightened brain vulnerability to hypoxic-ischemic encephalopathy and the development of neurological diseases in the postnatal life. The underlying mechanisms are not well understood. However, glucocorticoids may play a crucial role in epigenetic programming of neurological disorders of fetal origins. This review summarizes the recent studies about the effects of fetal stress on the abnormal brain development, focusing on the cellular, molecular and epigenetic mechanisms and highlighting the central effects of glucocorticoids on programming of hypoxic-ischemic-sensitive phenotype in the neonatal brain, which may enhance the understanding of brain pathophysiology resulting from fetal stress and help explore potential targets of timely diagnosis, prevention and intervention in neonatal hypoxic-ischemic encephalopathy and other brain disorders.
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Muhammad A, Carroll C, Kolb B. Stress during development alters dendritic morphology in the nucleus accumbens and prefrontal cortex. Neuroscience 2012; 216:103-9. [PMID: 22542675 DOI: 10.1016/j.neuroscience.2012.04.041] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 03/30/2012] [Accepted: 04/17/2012] [Indexed: 10/28/2022]
Abstract
The long-term effects of stress during development have been well characterized. However, the effects of developmental stress on the underlying neurological mechanisms related to the reward system are not well understood. The present report studied the long term effects of stress during development on the structural plasticity in the cortical and subcortical regions. Rats exposed to stress during embryonic development (prenatal stress; PS) or soon after birth (maternal separation; MS) were studied for structural alteration at the neuronal level in the nucleus accumbens (NAc), orbital frontal cortex (OFC), and medial prefrontal cortex (mPFC). The findings show that stress during development increased dendritic branching, length, and spine density in the NAc, and subregions of the PFC. PS experience increased dendritic branching and length in the mPFC apical and basilar dendrites. In contrast, a PS-associated decrease in dendritic branching and length was observed in the basilar branches of the OFC. MS resulted in an increase in dendritic growth and spine density in the subregions of the PFC. The effect of PS on neuroanatomy was more robust than MS despite the shorter duration and intensity. The altered dendritic growth and spine density associated with stress during development could have potential impact on NAc and PFC related behaviors.
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65
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Parental enrichment and offspring development: Modifications to brain, behavior and the epigenome. Behav Brain Res 2012; 228:294-8. [DOI: 10.1016/j.bbr.2011.11.036] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Revised: 11/24/2011] [Accepted: 11/26/2011] [Indexed: 11/22/2022]
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66
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Mychasiuk R, Gibb R, Kolb B. Prenatal stress produces sexually dimorphic and regionally specific changes in gene expression in hippocampus and frontal cortex of developing rat offspring. Dev Neurosci 2012; 33:531-8. [PMID: 22286693 DOI: 10.1159/000335524] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 11/30/2011] [Indexed: 01/19/2023] Open
Abstract
Prenatal stress has been known to induce structural changes in the brain and lead to negative psychological well-being. To further understanding of the mechanisms that underlie these effects, whole genome microarray analysis was used to analyze gene expression changes in the developing brain. Epigenetic changes in the hippocampus and frontal cortex of offspring exposed to stress during gestation were investigated. Biological process ontology and pathway analysis was used to increase understanding of the changes produced in response to prenatal stress. The study identified over 700 genes in the frontal cortex and hippocampus that are differentially expressed following prenatal stress. The epigenetic changes demonstrate sex-dependent and region-specific profiles, exhibiting very little overlap between sexes and brain area. Frontal cortex changes were largely related to neurotransmitter function, whereas hippocampal changes were more prominent in females and concentrated around growth factors. These findings have important implications for generalized intervention strategies using a single methodology for all individuals.
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Affiliation(s)
- Richelle Mychasiuk
- Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Lethbridge, Alta., Canada
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67
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Epigenetic programming of neurodegenerative diseases by an adverse environment. Brain Res 2012; 1444:96-111. [PMID: 22330722 DOI: 10.1016/j.brainres.2012.01.038] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Revised: 01/13/2012] [Accepted: 01/17/2012] [Indexed: 02/02/2023]
Abstract
Experience and environment can critically influence the risk and progression of neurodegenerative disorders. Epigenetic mechanisms, such as miRNA expression, DNA methylation, and histone modifications, readily respond to experience and environmental factors. Here we propose that epigenetic regulation of gene expression and environmental modulation thereof may play a key role in the onset and course of common neurological conditions, including Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis. For example, epigenetic mechanisms may mediate long-term responses to adverse experience, such as stress, to affect disease susceptibility and the course of neurodegenerative events. This review introduces the epigenetic components and their possible role in mediating neuropathological processes in response to stress. We argue that epigenetic modifications will affect neurodegenerative events through altered gene function. The study of epigenetic states in neurodegenerative diseases presents an opportunity to gain new insights into risk factors and pathogenic mechanisms. Moreover, research into epigenetic regulation of disease may revolutionize health care by opening new avenues of personalized, preventive and curative medicine.
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68
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Mychasiuk R, Gibb R, Kolb B. Prenatal stress alters dendritic morphology and synaptic connectivity in the prefrontal cortex and hippocampus of developing offspring. Synapse 2011; 66:308-14. [PMID: 22121047 DOI: 10.1002/syn.21512] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 10/19/2011] [Accepted: 11/14/2011] [Indexed: 01/16/2023]
Abstract
The current study used stereological techniques in combination with Golg-Cox methods to examine the neuroanatomical alterations in the prefrontal cortex and hippocampus of developing offspring exposed to gestational stress. Morphological changes in dendritic branching, length, and spine density, were examined at weaning along with changes in actual numbers of neurons. Using this information we generated a gross estimation of synaptic connectivity. The results showed region-specific and sex-dependent alterations to neuroanatomy in response to prenatal stress. The two regions of the prefrontal cortex, medial prefrontal, and orbital prefrontal cortices, exhibited sexually dimorphic, opposite changes, in synaptic connectivity in response to the same experience. Both male and female offspring demonstrated a loss of neuron number and estimated synapse number in the hippocampus despite exhibiting increased spine density. The results from this study suggest that prenatal stress alters normal development and the organization of neuronal circuits in both neocortex and hippocampus early in development and thus likely influences the course of later experience-dependent synaptic changes.
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Affiliation(s)
- Richelle Mychasiuk
- Canadian Centre for Behavioural Neuroscience, University of Lethbridge, 4401 University Drive, Lethbridge, Alberta, Canada.
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Braun K. The prefrontal-limbic system: development, neuroanatomy, function, and implications for socioemotional development. Clin Perinatol 2011; 38:685-702. [PMID: 22107898 DOI: 10.1016/j.clp.2011.08.013] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Abstract
The knowledge that neonatal emotional experience and associated learning processes are critical in the maturation of prefronto-limbic circuits emphasizes the importance of preterm and neonatal care. The further improvement of care and intervention strategies requires a deeper understanding of epigenetic mechanisms mediating experience-induced synaptic reorganization underlying the emergence of emotional and cognitive behavioral traits. Interdisciplinary research efforts are needed in which pediatricians and developmental biologists and psychologists merge their knowledge, concepts, and methodology. The hope is that the translational relevance of research efforts can be improved through a greater interaction between basic and clinical scientists.
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Affiliation(s)
- Katharina Braun
- Department of Zoology and Developmental Neurobiology, Institute of Biology, Otto von Guericke University Magdeburg, Leipziger Street 44, Magdeburg, Germany.
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70
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Popova NK, Morozova MV, Naumenko VS. Ameliorative effect of BDNF on prenatal ethanol and stress exposure-induced behavioral disorders. Neurosci Lett 2011; 505:82-6. [PMID: 22005582 DOI: 10.1016/j.neulet.2011.09.066] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 09/12/2011] [Accepted: 09/29/2011] [Indexed: 11/17/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) plays critical role in neuronal development, function, survival and plasticity of mature neurons. The present experiments investigated whether BDNF ameliorates the damaging effect of prenatal ethanol and stress exposure on behavior in offspring. Prenatal exposure of ethanol and stress combined during gestation inverted sexual partner preference of male offspring, increased social contacts with juvenile male mouse and stereotypic burying activity in the marble-burying test suggesting predisposition to homosexuality and to obsessive-compulsive disorder. Centrally administered BDNF (300ng i.c.v.) restored sexual female preference of male adult offspring and decreased marble-burying activity. Ameliorative effect was shown in 7-10 days after BDNF administration. The results provide the first evidence that BDNF improves epigenetic impairment of behavior and may have profound implications in the treatment of neurologic disorders induced by early environmental challenges.
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Affiliation(s)
- Nina K Popova
- Department of Behavioral Neurogenomics, Institute of Cytology and Genetics, Siberian Division of the Russian Academy of Sciences, Lavrentyeva av. 10, 630090 Novosibirsk, Russia.
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71
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Kolb B, Mychasiuk R, Williams P, Gibb R. Brain plasticity and recovery from early cortical injury. Dev Med Child Neurol 2011; 53 Suppl 4:4-8. [PMID: 21950386 DOI: 10.1111/j.1469-8749.2011.04054.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Neocortical development represents more than a simple unfolding of a genetic blueprint: rather, it represents a complex dance of genetic and environmental events that interact to adapt the brain to fit a particular environmental context. Most cortical regions are sensitive to a wide range of experiential factors during development and later in life, but the injured cortex appears to be unusually sensitive to perinatal experiences. This paper reviews the factors that influence how normal and injured brains (both focal and ischemic injuries) develop and adapt into adulthood. Such factors include prenatal experiences in utero as well as postnatal experiences throughout life. Examples include the effects of sensory and motor stimulation, psychoactive drugs (including illicit and prescription drugs), maternal and postnatal stress, neurotrophic factors, and pre- and postnatal diet. All these factors influence cerebral development and influence recovery from brain injury during development.
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Affiliation(s)
- Bryan Kolb
- Department of Neuroscience, University of Lethbridge, Alberta, Canada.
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72
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Mychasiuk R, Gibb R, Kolb B. Prenatal bystander stress induces neuroanatomical changes in the prefrontal cortex and hippocampus of developing rat offspring. Brain Res 2011; 1412:55-62. [PMID: 21816391 DOI: 10.1016/j.brainres.2011.07.023] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 06/24/2011] [Accepted: 07/10/2011] [Indexed: 11/30/2022]
Abstract
The rapid period of growth and development that occurs prenatally renders the brain vulnerable to experiences that may disrupt cortical plasticity. Although there is extensive literature examining anatomical changes in fully matured brain, there has been very little investigation of younger offspring. The current study used an indirect prenatal bystander stress and analyzed neuroanatomical changes in postnatal day 21 (P21) Long Evans rats. Dendritic architecture (dendritic length, branch order, and spine density) along with cell quantification (neuron and glia) was generated for layer 3 pyramidal cells of the medial prefrontal cortex (mPFC/Cg3), orbital prefrontal cortex (OFC/AID), and CA1 of the hippocampus. We found that prenatal bystander stress significantly altered the complexity and length of dendritic arbor, the density of excitatory spines and the actual volume of neuronal and glial cell numbers in the mPFC, OFC, and CA1 of developing rat offspring. Neuroanatomical changes of this extent occurring at such a critical time period will likely impact healthy maturation of the brain and long-term development.
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Affiliation(s)
- Richelle Mychasiuk
- Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Canada.
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73
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Kolb B, Teskey GC. Age, experience, injury, and the changing brain. Dev Psychobiol 2010; 54:311-25. [DOI: 10.1002/dev.20515] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Accepted: 10/04/2010] [Indexed: 01/27/2023]
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