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Perinatal programming of adult hippocampal structure and function; emerging roles of stress, nutrition and epigenetics. Trends Neurosci 2013; 36:621-31. [PMID: 23998452 DOI: 10.1016/j.tins.2013.08.002] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 08/05/2013] [Accepted: 08/06/2013] [Indexed: 11/22/2022]
Abstract
Early-life stress lastingly affects adult cognition and increases vulnerability to psychopathology, but the underlying mechanisms remain elusive. In this Opinion article, we propose that early nutritional input together with stress hormones and sensory stimuli from the mother during the perinatal period act synergistically to program the adult brain, possibly via epigenetic mechanisms. We hypothesize that stress during gestation or lactation affects the intake of macro- and micronutrients, including dietary methyl donors, and/or impairs the dam's metabolism, thereby altering nutrient composition and intake by the offspring. In turn, this may persistently modulate gene expression via epigenetic programming, thus altering hippocampal structure and cognition. Understanding how the combination of stress, nutrition, and epigenetics shapes the adult brain is essential for effective therapies.
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Cao X, Huang S, Cao J, Chen T, Zhu P, Zhu R, Su P, Ruan D. The timing of maternal separation affects morris water maze performance and long-term potentiation in male rats. Dev Psychobiol 2013; 56:1102-9. [DOI: 10.1002/dev.21130] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Accepted: 03/29/2013] [Indexed: 02/05/2023]
Affiliation(s)
- Xiujing Cao
- Department of Child and Maternal Health Care; School of Public Health, Anhui Medical University; Hefei, Anhui 230032, P.R. China
| | - Shenghai Huang
- Department of Microbiology; Anhui Medical University; Hefei, Anhui 230032, P.R. China
| | - Jiejie Cao
- Department of Child and Maternal Health Care; School of Public Health, Anhui Medical University; Hefei, Anhui 230032, P.R. China
| | - Tingting Chen
- Department of Child and Maternal Health Care; School of Public Health, Anhui Medical University; Hefei, Anhui 230032, P.R. China
| | - Ping Zhu
- Department of Child and Maternal Health Care; School of Public Health, Anhui Medical University; Hefei, Anhui 230032, P.R. China
| | - Rui Zhu
- Department of Child and Maternal Health Care; School of Public Health, Anhui Medical University; Hefei, Anhui 230032, P.R. China
| | - Puyu Su
- Department of Child and Maternal Health Care; School of Public Health, Anhui Medical University; Hefei, Anhui 230032, P.R. China
| | - Diyun Ruan
- School of Life Science; University of Science and Technology of China; Hefei, Anhui 230027, P.R. China
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Brewster AL, Lugo JN, Patil VV, Lee WL, Qian Y, Vanegas F, Anderson AE. Rapamycin reverses status epilepticus-induced memory deficits and dendritic damage. PLoS One 2013; 8:e57808. [PMID: 23536771 PMCID: PMC3594232 DOI: 10.1371/journal.pone.0057808] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 01/26/2013] [Indexed: 12/27/2022] Open
Abstract
Cognitive impairments are prominent sequelae of prolonged continuous seizures (status epilepticus; SE) in humans and animal models. While often associated with dendritic injury, the underlying mechanisms remain elusive. The mammalian target of rapamycin complex 1 (mTORC1) pathway is hyperactivated following SE. This pathway modulates learning and memory and is associated with regulation of neuronal, dendritic, and glial properties. Thus, in the present study we tested the hypothesis that SE-induced mTORC1 hyperactivation is a candidate mechanism underlying cognitive deficits and dendritic pathology seen following SE. We examined the effects of rapamycin, an mTORC1 inhibitor, on the early hippocampal-dependent spatial learning and memory deficits associated with an episode of pilocarpine-induced SE. Rapamycin-treated SE rats performed significantly better than the vehicle-treated rats in two spatial memory tasks, the Morris water maze and the novel object recognition test. At the molecular level, we found that the SE-induced increase in mTORC1 signaling was localized in neurons and microglia. Rapamycin decreased the SE-induced mTOR activation and attenuated microgliosis which was mostly localized within the CA1 area. These findings paralleled a reversal of the SE-induced decreases in dendritic Map2 and ion channels levels as well as improved dendritic branching and spine density in area CA1 following rapamycin treatment. Taken together, these findings suggest that mTORC1 hyperactivity contributes to early hippocampal-dependent spatial learning and memory deficits and dendritic dysregulation associated with SE.
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Affiliation(s)
- Amy L. Brewster
- Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital and Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Joaquin N. Lugo
- Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital and Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Vinit V. Patil
- Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital and Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Wai L. Lee
- Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital and Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Yan Qian
- Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital and Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Fabiola Vanegas
- Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital and Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Anne E. Anderson
- Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital and Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neurology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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54
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Sex, stress, and epigenetics: regulation of behavior in animal models of mood disorders. Biol Sex Differ 2013; 4:1. [PMID: 23331332 PMCID: PMC3586570 DOI: 10.1186/2042-6410-4-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 12/31/2012] [Indexed: 01/30/2023] Open
Abstract
Women have a higher incidence of stress related disorders including depression and generalized anxiety disorder, and epigenetic mechanisms likely contribute to this sex difference. Evidence from preclinical research suggests that epigenetic mechanisms are responsible for both sexual dimorphism of brain regions and sensitivity of the stress response. Epigenetic modifications such as DNA methylation and histone modifications can occur transgenerationally, developmentally, or in response to environmental stimuli such as stress exposure. This review will provide an overview of the various forms of epigenetic modifications observed in the central nervous system and will explain how these mechanisms contribute to a sexually dimorphic brain. It will also discuss the ways in which epigenetic alterations coincide with, and functionally contribute to, the behavioral response to stress across the lifespan. Ultimately, this review will focus on novel research utilizing animal models to investigate sex differences in epigenetic mechanisms that influence susceptibility to stress. Exploration of this relationship reveals epigenetic mechanisms with the potential to explain sexual dimorphism in the occurrence of stress related disorders.
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Pesonen AK, Eriksson JG, Heinonen K, Kajantie E, Tuovinen S, Alastalo H, Henriksson M, Leskinen J, Osmond C, Barker DJP, Räikkönen K. Cognitive ability and decline after early life stress exposure. Neurobiol Aging 2013; 34:1674-9. [PMID: 23337341 DOI: 10.1016/j.neurobiolaging.2012.12.012] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 11/30/2012] [Accepted: 12/18/2012] [Indexed: 01/08/2023]
Abstract
We examined the effects of early life stress on cognitive ability and decline among men of the Helsinki Birth Cohort Study, 10% of whom were separated temporarily (mean age at separation = 4.1 years) from their parent(s) during World War II. The men underwent the Finnish Defense Forces Basic Intellectual Ability Test twice, at 20 years and retest at 70 years. Compared with the men without childhood separation and matched for year of birth (n = 186), men separated from their parents (n = 93) scored lower by 5.5 (95% confidence interval [CI], -9.2 to -1.7), 4.2 (95% CI, -8.1 to -0.3), 3.1 (95% CI, -7.0 to 0.8), and 4.5 (95% CI, -10.5 to -1.4) standardized points (SD = 15) on verbal, visuospatial, arithmetic, and general cognitive ability, respectively, at 70 years. Longer duration of separation was associated with lower test scores. Though early life stress was also associated significantly with weaker cognitive performance at the ages 20 and 70 years, it was not associated with cognitive decline over the 50-year period within this sample.
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56
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Karsten CA, Baram TZ. How Does a Neuron "know" to Modulate Its Epigenetic Machinery in Response to Early-Life Environment/Experience? Front Psychiatry 2013; 4:89. [PMID: 23966959 PMCID: PMC3744051 DOI: 10.3389/fpsyt.2013.00089] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 07/30/2013] [Indexed: 12/27/2022] Open
Abstract
Exciting information is emerging about epigenetic mechanisms and their role in long-lasting changes of neuronal gene expression. Whereas these mechanisms are active throughout life, recent findings point to a critical window of early postnatal development during which neuronal gene expression may be persistently "re-programed" via epigenetic modifications. However, it remains unclear how the epigenetic machinery is modulated. Here we focus on an important example of early-life programing: the effect of sensory input from the mother on expression patterns of key stress-related genes in the developing brain. We focus on the lasting effects of this early-life experience on corticotropin-releasing hormone (CRH) gene expression in the hypothalamus, and describe recent work that integrates organism-wide signals with cellular signals that in turn impact epigenetic regulation. We describe the operational brain networks that convey sensory input to CRH-expressing cells, and highlight the resulting "re-wiring" of synaptic connectivity to these neurons. We then move from intercellular to intracellular mechanisms, speculating about the induction, and maintenance of lifelong CRH repression provoked by early-life experience. Elucidating such pathways is critical for understanding the enduring links between experience and gene expression. In the context of responses to stress, such mechanisms should contribute to vulnerability or resilience to post-traumatic stress disorder (PTSD) and other stress-related disorders.
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Affiliation(s)
- Carley A Karsten
- Department of Anatomy and Neurobiology, University of California-Irvine , Irvine, CA , USA ; Department of Pediatrics, University of California-Irvine , Irvine, CA , USA
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57
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Baram TZ, Solodkin A, Davis EP, Stern H, Obenaus A, Sandman CA, Small SL. Fragmentation and unpredictability of early-life experience in mental disorders. Am J Psychiatry 2012; 169:907-15. [PMID: 22885631 PMCID: PMC3483144 DOI: 10.1176/appi.ajp.2012.11091347] [Citation(s) in RCA: 165] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Maternal sensory signals in early life play a crucial role in programming the structure and function of the developing brain, promoting vulnerability or resilience to emotional and cognitive disorders. In rodent models of early-life stress, fragmentation and unpredictability of maternally derived sensory signals provoke persistent cognitive and emotional dysfunction in offspring. Similar variability and inconsistency of maternal signals during both gestation and early postnatal human life may influence development of emotional and cognitive functions, including those that underlie later depression and anxiety.
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58
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Kosten TA, Kim JJ, Lee HJ. Early life manipulations alter learning and memory in rats. Neurosci Biobehav Rev 2012; 36:1985-2006. [PMID: 22819985 DOI: 10.1016/j.neubiorev.2012.07.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Revised: 07/04/2012] [Accepted: 07/11/2012] [Indexed: 12/24/2022]
Abstract
Much research shows that early life manipulations have enduring behavioral, neural, and hormonal effects. However, findings of learning and memory performance vary widely across studies. We reviewed studies in which pre-weaning rat pups were exposed to stressors and tested on learning and memory tasks in adulthood. Tasks were classified as aversive conditioning, inhibitory learning, or spatial/relational memory. Variables of duration, type, and timing of neonatal manipulation and sex and strain of animals were examined to determine if any predict enhanced or impaired performance. Brief separations enhanced and prolonged separations impaired performance on spatial/relational tasks. Performance was impaired in aversive conditioning and enhanced in inhibitory learning tasks regardless of manipulation duration. Opposing effects on performance for spatial/relational memory also depended upon timing of manipulation. Enhanced performance was likely if the manipulation occurred during postnatal week 3 but performance was impaired if it was confined to the first two postnatal weeks. Thus, the relationship between early life experiences and adulthood learning and memory performance is multifaceted and decidedly task-dependent.
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Affiliation(s)
- Therese A Kosten
- Menninger Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX 77030, USA.
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59
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Abstract
There are numerous examples of enduring effects of early experience on gene transcription and neural function. We review the emerging evidence for epigenetics as a candidate mechanism for such effects. There is now evidence that intracellular signals activated by environmental events can directly modify the epigenetic state of the genome, including CpG methylation, histone modifications and microRNAs. We suggest that this process reflects an activity-dependent epigenetic plasticity at the level of the genome, comparable with that observed at the synapse. This epigenetic plasticity mediates neuronal differentiation and phenotypic plasticity, including that associated with learning and memory. Altered epigenetic states are also associated with the risk for and expression of mental disorders. In a broader context, these studies define a biological basis for the interplay between environmental signals and the genome in the regulation of individual differences in behavior, cognition and physiology, as well as the risk for psychopathology.
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Affiliation(s)
- Judy Sng
- Integrative Neuroscience Program, Singapore Institute for Clinical Sciences, 30 Medial Drive, Singapore.
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60
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Abstract
Childhood traumatic events hamper the development of the hippocampus and impair declarative memory in susceptible individuals. Persistent elevations of hippocampal corticotropin-releasing factor (CRF), acting through CRF receptor 1 (CRF₁), in experimental models of early-life stress have suggested a role for this endogenous stress hormone in the resulting structural modifications and cognitive dysfunction. However, direct testing of this possibility has been difficult. In the current study, we subjected conditional forebrain CRF₁ knock-out (CRF₁-CKO) mice to an impoverished postnatal environment and examined the role of forebrain CRF₁ in the long-lasting effects of early-life stress on learning and memory. Early-life stress impaired spatial learning and memory in wild-type mice, and postnatal forebrain CRF overexpression reproduced these deleterious effects. Cognitive deficits in stressed wild-type mice were associated with disrupted long-term potentiation (LTP) and a reduced number of dendritic spines in area CA3 but not in CA1. Forebrain CRF₁ deficiency restored cognitive function, LTP and spine density in area CA3, and augmented CA1 LTP and spine density in stressed mice. In addition, early-life stress differentially regulated the amount of hippocampal excitatory and inhibitory synapses in wild-type and CRF₁-CKO mice, accompanied by alterations in the neurexin-neuroligin complex. These data suggest that the functional, structural and molecular changes evoked by early-life stress are at least partly dependent on persistent forebrain CRF₁ signaling, providing a molecular target for the prevention of cognitive deficits in adults with a history of early-life adversity.
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61
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Gunn BG, Brown AR, Lambert JJ, Belelli D. Neurosteroids and GABA(A) Receptor Interactions: A Focus on Stress. Front Neurosci 2011; 5:131. [PMID: 22164129 PMCID: PMC3230140 DOI: 10.3389/fnins.2011.00131] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Accepted: 11/14/2011] [Indexed: 11/13/2022] Open
Abstract
Since the pioneering discovery of the rapid CNS depressant actions of steroids by the "father of stress," Hans Seyle 70 years ago, brain-derived "neurosteroids" have emerged as powerful endogenous modulators of neuronal excitability. The majority of the intervening research has focused on a class of naturally occurring steroids that are metabolites of progesterone and deoxycorticosterone, which act in a non-genomic manner to selectively augment signals mediated by the main inhibitory receptor in the CNS, the GABA(A) receptor. Abnormal levels of such neurosteroids associate with a variety of neurological and psychiatric disorders, suggesting that they serve important physiological and pathophysiological roles. A compelling case can be made to implicate neurosteroids in stress-related disturbances. Here we will critically appraise how brain-derived neurosteroids may impact on the stress response to acute and chronic challenges, both pre- and postnatally through to adulthood. The pathological implications of such actions in the development of psychiatric disturbances will be discussed, with an emphasis on the therapeutic potential of neurosteroids for the treatment of stress-associated disorders.
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Affiliation(s)
- Benjamin G Gunn
- Division of Neuroscience, Medical Research Institute, Ninewells Hospital and Medical School, Ninewells Hospital, University of Dundee Dundee, UK
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62
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Yehuda R, Seckl J. Minireview: Stress-related psychiatric disorders with low cortisol levels: a metabolic hypothesis. Endocrinology 2011; 152:4496-503. [PMID: 21971152 DOI: 10.1210/en.2011-1218] [Citation(s) in RCA: 156] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Several stress-associated neuropsychiatric disorders, notably posttraumatic stress disorder and chronic pain and fatigue syndromes, paradoxically exhibit somewhat low plasma levels of the stress hormone cortisol. The effects appear greatest in those initially traumatized in early life, implying a degree of developmental programming, perhaps of both lower cortisol and vulnerability to psychopathology. In these conditions, lowered cortisol is not due to any adrenal or pituitary insufficiency. Instead, two processes appear involved. First, there is increased target cell sensitivity to glucocorticoid action, notably negative feedback upon the hypothalamic-pituitary-adrenal (stress) axis. Altered density of the glucocorticoid receptor is inferred, squaring with much preclinical data showing early life challenges can permanently program glucocorticoid receptors in a tissue-specific manner. These effects involve epigenetic mechanisms. Second, early life trauma/starvation induces long-lasting lowering of glucocorticoid catabolism, specifically by 5α-reductase type 1 (predominantly a liver enzyme) and 11β-hydroxysteroid dehydrogenase type 2 (in kidney), an effect also seen in model systems. These changes reflect a plausible early-life adaptation to increase the persistence of active cortisol in liver (to maximize fuel output) and kidney (to increase salt retention) without elevation of circulating levels, thus avoiding their deleterious effects on brain and muscle. Modestly lowered circulating cortisol and increased vulnerability to stress-associated disorders may be the outcome. This notion implies a vulnerable early-life phenotype may be discernable and indicates potential therapy by modest glucocorticoid replacement. Indeed, early clinical trials with cortisol have shown a modicum of promise.
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Affiliation(s)
- Rachel Yehuda
- Mount Sinai School of Medicine, Department of Psychiatry, Traumatology and Stress Studies Division, New York, New York 10029, USA
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63
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Badowska-Szalewska E, Spodnik E, Ludkiewicz B, Klejbor I, Moryś J. Nerve growth factor (NGF) immunoreactive neurons in the juvenile rat hippocampus: response to acute and long-term high-light open-field (HL-OF) or forced swim (FS) stress stimulation. Neuroscience 2011; 199:491-500. [PMID: 22027234 DOI: 10.1016/j.neuroscience.2011.10.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 09/13/2011] [Accepted: 10/09/2011] [Indexed: 12/30/2022]
Abstract
This study aimed at examining and comparing the influence of two different stress stimuli on the density (number of cells/mm²) of nerve growth factor (NGF) containing neurons in the hippocampal CA1 and CA3 pyramidal cell layers and the dentate gyrus (DG) granule cell layer in juvenile rats (P28; P-postnatal day). The high-light open-field (HL-OF) test and forced swim (FS) test were employed to investigate the effects of a single, 15-min acute exposure and repeated (15 min daily for 21 days) long-term exposure to stress. In order to detect NGF-ir neurons, immunohistochemical (-ir) techniques were used. In comparison with nonstressed animals, acute and long-term HL-OF or FS stimulation resulted in a marked increase (P<0.001) in the density of NGF-ir containing cells in all the hippocampal structures. The frequency of stress application (acute vs. long-term), however, did not have a substantial impact on the studied parameter, with the exception of the CA3 sector, where a decreased density (P<0.001) of NGF-ir neurons was observed after long-term exposure to FS. It may be concluded that a rise in the density of NGF-ir neurons in the juvenile rat hippocampus after exposure to HL-OF or FS stressors could have affected the activity of the hypothalamic-pituitary-adrenocortical (HPA) stress axis. Prolonged HL-OF or FS stress was probably aggravating enough not to trigger the habituation process. The type of stressor applied (HL-OF vs. FS) was not essentially a factor determining the density of NGF-ir cells in the hippocampus.
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Affiliation(s)
- E Badowska-Szalewska
- Department of Anatomy and Neurobiology, Medical University of Gdańsk, Dębinki 1 Street, 80-211 Gdańsk, Poland.
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64
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Winkelmann-Duarte EC, Padilha-Hoffmann CB, Martins DF, Schuh AFS, Fernandes MC, Santin R, Merlo S, Sanvitto GL, Lucion AB. Early-life environmental intervention may increase the number of neurons, astrocytes, and cellular proliferation in the hippocampus of rats. Exp Brain Res 2011; 215:163-72. [DOI: 10.1007/s00221-011-2881-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Accepted: 09/17/2011] [Indexed: 12/23/2022]
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65
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Rinaman L, Banihashemi L, Koehnle TJ. Early life experience shapes the functional organization of stress-responsive visceral circuits. Physiol Behav 2011; 104:632-40. [PMID: 21497616 PMCID: PMC3139736 DOI: 10.1016/j.physbeh.2011.04.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Revised: 04/06/2011] [Accepted: 04/08/2011] [Indexed: 01/07/2023]
Abstract
Emotions are closely tied to changes in autonomic (i.e., visceral motor) function, and interoceptive sensory feedback from body to brain exerts powerful modulatory control over motivation, affect, and stress responsiveness. This manuscript reviews evidence that early life experience can shape the structure and function of central visceral circuits that underlie behavioral and physiological responses to emotive and stressful events. The review begins with a general discussion of descending autonomic and ascending visceral sensory pathways within the brain, and then summarizes what is known about the postnatal development of these central visceral circuits in rats. Evidence is then presented to support the view that early life experience, particularly maternal care, can modify the developmental assembly and structure of these circuits in a way that impacts later stress responsiveness and emotional behavior. The review concludes by presenting a working hypothesis that endogenous cholecystokinin signaling and subsequent recruitment of gastric vagal sensory inputs to the caudal brainstem may be an important mechanism by which maternal care influences visceral circuit development in rat pups. Early life experience may contribute to meaningful individual differences in emotionality and stress responsiveness by shaping the postnatal developmental trajectory of central visceral circuits.
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Affiliation(s)
- Linda Rinaman
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA.
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66
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Curley JP, Jensen CL, Mashoodh R, Champagne FA. Social influences on neurobiology and behavior: epigenetic effects during development. Psychoneuroendocrinology 2011; 36:352-71. [PMID: 20650569 PMCID: PMC2980807 DOI: 10.1016/j.psyneuen.2010.06.005] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2010] [Revised: 06/10/2010] [Accepted: 06/14/2010] [Indexed: 02/04/2023]
Abstract
The quality of the social environment can have profound influences on the development and activity of neural systems with implications for numerous behavioral and physiological responses, including the expression of emotionality. Though social experiences occurring early in development may be particularly influential on the developing brain, there is continued plasticity within these neural circuits amongst juveniles and into early adulthood. In this review, we explore the evidence derived from studies in rodents which illustrates the social modulation during development of neural systems, with a particular emphasis on those systems in which a long-term effect is observed. One possible explanation for the persistence of dynamic changes in these systems in response to the environment is the involvement of epigenetic mechanisms, and here we discuss recent studies which support the role of these mechanisms in mediating the link between social experiences, gene expression, neurobiological changes, and behavioral variation. This literature raises critical questions about the interaction between neural systems, the concordance between neural and behavioral changes, sexual dimorphism in effects, the importance of considering individual differences in response to the social environment, and the potential of an epigenetic perspective in advancing our understanding of the pathways leading to variations in mental health.
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Affiliation(s)
- J P Curley
- Columbia University, Department of Psychology, 1190 Amsterdam Avenue, New York, NY 10027, USA
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67
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McClelland S, Korosi A, Cope J, Ivy A, Baram TZ. Emerging roles of epigenetic mechanisms in the enduring effects of early-life stress and experience on learning and memory. Neurobiol Learn Mem 2011; 96:79-88. [PMID: 21338703 DOI: 10.1016/j.nlm.2011.02.008] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 02/04/2011] [Accepted: 02/10/2011] [Indexed: 12/25/2022]
Abstract
Epigenetic mechanisms are involved in programming gene expression throughout development. In addition, they are key contributors to the processes by which early-life experience fine-tunes the expression levels of key neuronal genes, governing learning and memory throughout life. Here we describe the long-lasting, bi-directional effects of early-life experience on learning and memory. We discuss how enriched postnatal experience enduringly augments spatial learning, and how chronic early-life stress results in persistent and progressive deficits in the structure and function of hippocampal neurons. The existing and emerging roles of epigenetic mechanisms in these fundamental neuroplasticity phenomena are illustrated.
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68
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Korosi A, Baram TZ. Plasticity of the stress response early in life: mechanisms and significance. Dev Psychobiol 2011; 52:661-70. [PMID: 20862706 DOI: 10.1002/dev.20490] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The concept that early-life experience influences the brain long-term has been extensively studied over the past 50 years, whereas genetic factors determine the sequence and levels of expression of specific neuronal genes, this genetic program can be modified enduringly as a result of experience taking place during critical developmental periods. This programming is of major importance because it appears to govern many behavioral and physiological phenotypes and promote susceptibility or resilience to disease. An established example of the consequences of early-life experience-induced programming includes the effects of maternal care, where patterns of augmented care result in decreased neuroendocrine stress responses, improved cognition and resilience to depression in the recipients of this care. Here, we discuss the nature and mechanisms of this programming phenomenon, focusing on work from our lab that was inspired by Seymour Levine and his fundamental contributions to the field.
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Affiliation(s)
- Aniko Korosi
- Department of Anatomy/Neurobiology, Pediatrics and Neurology, UC Irvine, CA 92697, USA.
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69
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Hippocampal dysfunction and cognitive impairments provoked by chronic early-life stress involve excessive activation of CRH receptors. J Neurosci 2010; 30:13005-15. [PMID: 20881118 DOI: 10.1523/jneurosci.1784-10.2010] [Citation(s) in RCA: 303] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Chronic stress impairs learning and memory in humans and rodents and disrupts long-term potentiation (LTP) in animal models. These effects are associated with structural changes in hippocampal neurons, including reduced dendritic arborization. Unlike the generally reversible effects of chronic stress on adult rat hippocampus, we have previously found that the effects of early-life stress endure and worsen during adulthood, yet the mechanisms for these clinically important sequelae are poorly understood. Stress promotes secretion of the neuropeptide corticotropin-releasing hormone (CRH) from hippocampal interneurons, activating receptors (CRF(1)) located on pyramidal cell dendrites. Additionally, chronic CRF(1) occupancy negatively affects dendritic arborization in mouse organotypic slice cultures, similar to the pattern observed in middle-aged, early-stressed (CES) rats. Here we found that CRH expression is augmented in hippocampus of middle-aged CES rats, and then tested whether the morphological defects and poor memory performance in these animals involve excessive activation of CRF(1) receptors. Central or peripheral administration of a CRF(1) blocker following the stress period improved memory performance of CES rats in novel-object recognition tests and in the Morris water maze. Consonant with these effects, the antagonist also prevented dendritic atrophy and LTP attenuation in CA1 Schaffer collateral synapses. Together, these data suggest that persistently elevated hippocampal CRH-CRF(1) interaction contributes importantly to the structural and cognitive impairments associated with early-life stress. Reducing CRF(1) occupancy post hoc normalized hippocampal function during middle age, thus offering potential mechanism-based therapeutic interventions for children affected by chronic stress.
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70
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Bagot RC, Meaney MJ. Epigenetics and the biological basis of gene x environment interactions. J Am Acad Child Adolesc Psychiatry 2010; 49:752-71. [PMID: 20643310 DOI: 10.1016/j.jaac.2010.06.001] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Revised: 05/31/2010] [Accepted: 06/07/2010] [Indexed: 10/18/2022]
Abstract
OBJECTIVE Child and adolescent psychiatry is rife with examples of the sustained effects of early experience on brain function. The study of behavioral genetics provides evidence for a relation between genomic variation and personality and with the risk for psychopathology. A pressing challenge is that of conceptually integrating findings from genetics into the study of personality without regressing to arguments concerning the relative importance of genomic variation versus nongenomic or environmental influences. METHOD Epigenetics refers to functionally relevant modifications to the genome that do not involve a change in nucleotide sequence. This review examines epigenetics as a candidate biological mechanism for gene x environment interactions, with a focus on environmental influences that occur during early life and that yield sustained effects on neural development and function. RESULTS The studies reviewed suggest that epigenetic remodeling occurs in response to the environmental activation of cellular signalling pathways associated with synaptic plasticity, epigenetic marks are actively remodeled during early development in response to environmental events that regulate neural development and function, and epigenetic marks are subject to remodeling by environmental influences even at later stages in development. CONCLUSION Epigenetic remodeling might serve as an ideal mechanism for phenotypic plasticity--the process whereby the environment interacts with the genome to produce individual differences in the expression of specific traits.
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Affiliation(s)
- Rosemary C Bagot
- Sackler Program for Epigenetics and Psychobiology, McGill University and Douglas Mental Health University Institute, Montreal, Canada
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71
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Synaptophysin immunoreactivity in the human hippocampus and neocortex from 6 to 41 weeks of gestation. J Neuropathol Exp Neurol 2010; 69:234-45. [PMID: 20142767 DOI: 10.1097/nen.0b013e3181d0151f] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
To assess the synaptic vesicle protein synaptophysin as a potential marker for maturation in the human fetal brain, synaptophysin immunoreactivity (sIR) was prospectively studied in postmortem sections of 162 normal human fetal and neonatal brains of both sexes from 6 to 41 weeks' gestational age. There was a consistent temporal and spatial pattern of sIR in the hippocampus and cerebral neocortex. In the rostral hippocampus, sIR was first apparent in the molecular zone of the dentate gyrus at 12 weeks, followed by CA2 at 14 weeks, CA3 and CA4 at 15 to 16 weeks, and CA1 at 19 weeks; it was incomplete until 26 weeks. In frontal neocortex, sIR developed in a laminar pattern above and below the cortical plate as early as 12 weeks, around Cajal-Retzius neurons of the molecular zone at 14 weeks, surrounding pyramidal neurons of Layers 5 and 6 at 16 weeks, and at the surface of neuronal somata in Layers 2 and 4 at 22 weeks. At 33 weeks, Layers 2 and 4 still had less sIR than other layers. Uniform sIR among all cortical layers was evident at 38 weeks. Ascending probable thalamocortical axons were reactive as early as 12 weeks and were best demonstrated by 26 weeks, after which increasing sIR in the neuropil diminished the contrast. The sIR was preserved for more than 96 hours postmortem, even in severely autolytic brains. We conclude that synaptophysin is a reliable marker in human fetal brain and that sIR provides the means for objective assessment of cerebral maturation in normal brains and to enable interpretation of abnormal synaptic patterns in pathological conditions.
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72
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Molecular mechanisms of early life stress—Lessons from mouse models. Neurosci Biobehav Rev 2010; 34:845-52. [DOI: 10.1016/j.neubiorev.2009.05.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Revised: 03/23/2009] [Accepted: 05/05/2009] [Indexed: 11/22/2022]
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73
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Zhang TY, Meaney MJ. Epigenetics and the environmental regulation of the genome and its function. Annu Rev Psychol 2010; 61:439-66, C1-3. [PMID: 19958180 DOI: 10.1146/annurev.psych.60.110707.163625] [Citation(s) in RCA: 287] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
There are numerous examples in psychology and other disciplines of the enduring effects of early experience on neural function. In this article, we review the emerging evidence for epigenetics as a candidate mechanism for these effects. Epigenetics refers to functionally relevant modifications to the genome that do not involve a change in nucleotide sequence. Such modifications include chemical marks that regulate the transcription of the genome. There is now evidence that environmental events can directly modify the epigenetic state of the genome. Thus studies with rodent models suggest that during both early development and in adult life, environmental signals can activate intracellular pathways that directly remodel the "epigenome," leading to changes in gene expression and neural function. These studies define a biological basis for the interplay between environmental signals and the genome in the regulation of individual differences in behavior, cognition, and physiology.
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Affiliation(s)
- Tie-Yuan Zhang
- Sackler Program for Epigenetics and Psychobiology of McGill University, Douglas Mental Health University Institute and the Singapore Institute for Clinical Sciences, Montreal, Quebec, H4H 1R3 Canada
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74
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Korosi A, Shanabrough M, McClelland S, Liu ZW, Borok E, Gao XB, Horvath TL, Baram TZ. Early-life experience reduces excitation to stress-responsive hypothalamic neurons and reprograms the expression of corticotropin-releasing hormone. J Neurosci 2010. [PMID: 20071535 DOI: 10.1532/jneurosci.4214-09.2010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Increased sensory input from maternal care attenuates neuroendocrine and behavioral responses to stress long term and results in a lifelong phenotype of resilience to depression and improved cognitive function. Whereas the mechanisms of this clinically important effect remain unclear, the early, persistent suppression of the expression of the stress neurohormone corticotropin-releasing hormone (CRH) in hypothalamic neurons has been implicated as a key aspect of this experience-induced neuroplasticity. Here, we tested whether the innervation of hypothalamic CRH neurons of rat pups that received augmented maternal care was altered in a manner that might promote the suppression of CRH expression and studied the cellular mechanisms underlying this suppression. We found that the number of excitatory synapses and the frequency of miniature excitatory synaptic currents onto CRH neurons were reduced in "care-augmented" rats compared with controls, as were the levels of the glutamate vesicular transporter vGlut2. In contrast, analogous parameters of inhibitory synapses were unchanged. Levels of the transcriptional repressor neuron-restrictive silencer factor (NRSF), which negatively regulates Crh gene transcription, were markedly elevated in care-augmented rats, and chromatin immunoprecipitation demonstrated that this repressor was bound to a cognate element (neuron-restrictive silencing element) on the Crh gene. Whereas the reduced excitatory innervation of CRH-expressing neurons dissipated by adulthood, increased NRSF levels and repression of CRH expression persisted, suggesting that augmented early-life experience reprograms Crh gene expression via mechanisms involving transcriptional repression by NRSF.
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Affiliation(s)
- Aniko Korosi
- Anatomy/Neurobiology and Pediatrics, University of California Irvine, Irvine, California 92697, USA
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75
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Early-life experience reduces excitation to stress-responsive hypothalamic neurons and reprograms the expression of corticotropin-releasing hormone. J Neurosci 2010; 30:703-13. [PMID: 20071535 DOI: 10.1523/jneurosci.4214-09.2010] [Citation(s) in RCA: 133] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Increased sensory input from maternal care attenuates neuroendocrine and behavioral responses to stress long term and results in a lifelong phenotype of resilience to depression and improved cognitive function. Whereas the mechanisms of this clinically important effect remain unclear, the early, persistent suppression of the expression of the stress neurohormone corticotropin-releasing hormone (CRH) in hypothalamic neurons has been implicated as a key aspect of this experience-induced neuroplasticity. Here, we tested whether the innervation of hypothalamic CRH neurons of rat pups that received augmented maternal care was altered in a manner that might promote the suppression of CRH expression and studied the cellular mechanisms underlying this suppression. We found that the number of excitatory synapses and the frequency of miniature excitatory synaptic currents onto CRH neurons were reduced in "care-augmented" rats compared with controls, as were the levels of the glutamate vesicular transporter vGlut2. In contrast, analogous parameters of inhibitory synapses were unchanged. Levels of the transcriptional repressor neuron-restrictive silencer factor (NRSF), which negatively regulates Crh gene transcription, were markedly elevated in care-augmented rats, and chromatin immunoprecipitation demonstrated that this repressor was bound to a cognate element (neuron-restrictive silencing element) on the Crh gene. Whereas the reduced excitatory innervation of CRH-expressing neurons dissipated by adulthood, increased NRSF levels and repression of CRH expression persisted, suggesting that augmented early-life experience reprograms Crh gene expression via mechanisms involving transcriptional repression by NRSF.
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76
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Fan H, Wang L, Guo F, Wei S, Zhao R. Neonatal intramuscular injection of plasmid encoding glucagon-like peptide-1 affects anxiety behaviour and expression of the hippocampal glucocorticoid receptor in adolescent rats. J Biosci 2010; 35:63-71. [DOI: 10.1007/s12038-010-0008-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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77
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Stamatakis A, Toutountzi E, Fragioudaki K, Kouvelas E, Stylianopoulou F, Mitsacos A. Selective effects of neonatal handling on rat brain N-methyl-d-aspartate receptors. Neuroscience 2009; 164:1457-67. [DOI: 10.1016/j.neuroscience.2009.09.032] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Revised: 08/25/2009] [Accepted: 09/15/2009] [Indexed: 10/20/2022]
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78
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Kiosterakis G, Stamatakis A, Diamantopoulou A, Fameli M, Stylianopoulou F. Long-term effects of neonatal handling on mu-opioid receptor levels in the brain of the offspring. Dev Psychobiol 2009; 51:439-49. [PMID: 19507200 DOI: 10.1002/dev.20383] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Neonatal handling is an experimental paradigm of an early experience which permanently alters hypothalamic-pituitary-adrenal axis function resulting in increased ability to cope with stress, and decreased emotionality. In the present work we investigated the effect of neonatal handling on adult rat brain mu-opioid receptor levels, since the opioid system is known to play an important role in emotional processing, anxiety and stress responses. Neonatal handling resulted in increased levels of mu-opioid receptors in the basolateral and central amygdaloid nuclei, in the CA3 and CA4 hippocampal areas, in the ventral tegmental area, the nucleus accumbens and the prefrontal cortex. Handled animals of both sexes had lower anxiety as measured in the elevated plus maze. The increased mu receptor levels could participate in the molecular mechanisms underlying the well-documented decreased stress and anxiety responses of handled animals.
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Affiliation(s)
- Georgios Kiosterakis
- Biology-Biochemistry Lab, Department of Basic Sciences, Faculty of Nursing, University of Athens, 123 Papadiamantopoulou str., 11527 Athens, Greece
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79
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Korosi A, Baram TZ. The pathways from mother's love to baby's future. Front Behav Neurosci 2009; 3:27. [PMID: 19826614 PMCID: PMC2759360 DOI: 10.3389/neuro.08.027.2009] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2009] [Accepted: 08/20/2009] [Indexed: 12/30/2022] Open
Abstract
Together with genetic factors, early-life experience governs the expression and function of stress-related genes throughout life. This, in turn, contributes to either resilience or vulnerability to depression and to aging-related cognitive decline. In humans and animal models, both the quality and quantity of early-life maternal care has been shown to be a predominant signal triggering bi-directional and enduring changes in expression profiles of genes including glucocorticoids and corticotropin releasing factor (CRH; hypothalamic and hippocampal), associated with the development of resilient or vulnerable phenotypes. However, many crucial questions remain unresolved. For examples, how is the maternal-derived signal transmitted to specific neuronal populations where enduring (likely epigenetic) regulation of gene expression takes place? What is the nature of this information? In other words, how do neurons know to ‘turn on’ epigenetic machinery? What are the direct functional consequences of altered gene expression? This review describes the voyage of recurrent bursts of sensory input from the mother (‘mother's love’) to CRH-expressing hypothalamic neurons that govern the magnitude of the response to stress. In addition, the acute and enduring effects of both nurturing and fragmented maternal care on the structure, cellular signaling and function of specific hippocampal and hypothalamic neurons are discussed. The evolving understanding of the processes initiated by the early life experience of ‘mother's love’ suggest novel molecular targets for prevention and therapy of stress-related affective and cognitive disorders.
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Affiliation(s)
- Aniko Korosi
- Anatomy/Neurobiology, Pediatrics and Neurology, University of California at Irvine Irvine, CA 92697-4475, USA
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80
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Cottrell EC, Seckl JR. Prenatal stress, glucocorticoids and the programming of adult disease. Front Behav Neurosci 2009; 3:19. [PMID: 19826624 PMCID: PMC2759372 DOI: 10.3389/neuro.08.019.2009] [Citation(s) in RCA: 414] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Accepted: 08/10/2009] [Indexed: 12/21/2022] Open
Abstract
Numerous clinical studies associate an adverse prenatal environment with the development of cardio-metabolic disorders and neuroendocrine dysfunction, as well as an increased risk of psychiatric diseases in later life. Experimentally, prenatal exposure to stress or excess glucocorticoids in a variety of animal models can malprogram offspring physiology, resulting in a reduction in birth weight and subsequently increasing the likelihood of disorders of cardiovascular function, glucose homeostasis, hypothalamic–pituitary–adrenal (HPA) axis activity and anxiety-related behaviours in adulthood. During fetal development, placental 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) provides a barrier to maternal glucocorticoids. Reduced placental 11β-HSD2 in human pregnancy correlates with lower birth weight and higher blood pressure in later life. Similarly, in animal models, inhibition or knockout of placental 11β-HSD2 lowers offspring birth weight, in part by reducing glucose delivery to the developing fetus in late gestation. Molecular mechanisms thought to underlie the programming effects of early life stress and glucocorticoids include epigenetic changes in target chromatin, notably affecting tissue-specific expression of the intracellular glucocorticoid receptor (GR). As such, excess glucocorticoids in early life can permanently alter tissue glucocorticoid signalling, effects which may have short-term adaptive benefits but increase the risk of later disease.
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Affiliation(s)
- Elizabeth C Cottrell
- Endocrinology Unit, Centre for Cardiovascular Science, The Queen's Medical Research Institute, University of Edinburgh Edinburgh, Scotland
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81
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Schmidt MV, Sterlemann V, Wagner K, Niederleitner B, Ganea K, Liebl C, Deussing JM, Berger S, Schütz G, Holsboer F, Müller MB. Postnatal glucocorticoid excess due to pituitary glucocorticoid receptor deficiency: differential short- and long-term consequences. Endocrinology 2009; 150:2709-16. [PMID: 19213843 DOI: 10.1210/en.2008-1211] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A tight regulation of hypothalamic-pituitary-adrenal (HPA) axis activity is essential for successful adaptation to stressful stimuli. Disruption of normal HPA axis development is a main risk factor for diseases such as posttraumatic stress disorder or depression, but the molecular mechanisms that lead to these long-term consequences are poorly understood. Here, we test the hypothesis that the pituitary glucocorticoid receptor (GR) is involved in regulating HPA axis function in neonatal and adult animals. Furthermore, we investigate whether postnatal hypercortisolism induced by pituitary GR deficiency is a main factor contributing to the persistent effects of early-life stress. Conditional knockout mice with a deletion of the GR at the pituitary (GR(POMCCre)) show excessive basal corticosterone levels during postnatal development, but not in adulthood. The hypercortisolemic state of neonatal GR(POMCCre) mice is accompanied by central gene expression changes of CRH and vasopressin in the paraventricular nucleus, but these alterations normalize at later ages. In adult mice, pituitary GR deficiency results in impaired glucocorticoid negative feedback. Furthermore, adult GR(POMCCre) mice display a more active coping strategy in the forced swim test, with no alterations in anxiety like behavior or cognitive functions. Postnatal GR antagonist treatment is able to prevent the long-term behavioral effects in GR(POMCCre) mice. In conclusion, we show that pituitary GRs are centrally involved in regulating HPA axis activity in neonates and mediate negative feedback regulation in adult animals. Postnatal glucocorticoid excess results in an altered stress-coping behavior in adult animals, with no effects on anxiety like behavior or cognition.
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82
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Marshall PJ, Kenney JW. Biological perspectives on the effects of early psychosocial experience. DEVELOPMENTAL REVIEW 2009. [DOI: 10.1016/j.dr.2009.05.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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83
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Panagiotaropoulos T, Diamantopoulou A, Stamatakis A, Dimitropoulou M, Stylianopoulou F. Learning of a T-maze by rat pups when contact with the mother is either permitted or denied. Neurobiol Learn Mem 2009; 91:2-12. [DOI: 10.1016/j.nlm.2008.09.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Revised: 09/16/2008] [Accepted: 09/18/2008] [Indexed: 10/21/2022]
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84
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Garoflos E, Stamatakis A, Rafrogianni A, Pondiki S, Stylianopoulou F. Neonatal handling on the first postnatal day leads to increased maternal behavior and fos levels in the brain of the newborn rat. Dev Psychobiol 2008; 50:704-13. [DOI: 10.1002/dev.20332] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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85
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Rice CJ, Sandman CA, Lenjavi MR, Baram TZ. A novel mouse model for acute and long-lasting consequences of early life stress. Endocrinology 2008; 149:4892-900. [PMID: 18566122 PMCID: PMC2582918 DOI: 10.1210/en.2008-0633] [Citation(s) in RCA: 353] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Chronic early-life stress (ES) exerts profound acute and long-lasting effects on the hypothalamic-pituitary-adrenal system, with relevance to cognitive function and affective disorders. Our ability to determine the molecular mechanisms underlying these effects should benefit greatly from appropriate mouse models because these would enable use of powerful transgenic methods. Therefore, we have characterized a mouse model of chronic ES, which was provoked in mouse pups by abnormal, fragmented interactions with the dam. Dam-pup interaction was disrupted by limiting the nesting and bedding material in the cages, a manipulation that affected this parameter in a dose-dependent manner. At the end of their week-long rearing in the limited-nesting cages, mouse pups were stressed, as apparent from elevated basal plasma corticosterone levels. In addition, steady-state mRNA levels of CRH in the hypothalamic paraventricular nucleus of ES-experiencing pups were reduced, without significant change in mRNA levels of arginine vasopressin. Rearing mouse pups in this stress-provoking cage environment resulted in enduring effects: basal plasma corticosterone levels were still increased, and CRH mRNA levels in paraventricular nucleus remained reduced in adult ES mice, compared with those of controls. In addition, hippocampus-dependent learning and memory functions were impaired in 4- to 8-month-old ES mice. In summary, this novel, robust model of chronic early life stress in the mouse results in acute and enduring neuroendocrine and cognitive abnormalities. This model should facilitate the examination of the specific genes and molecules involved in the generation of this stress as well as in its consequences.
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Affiliation(s)
- Courtney J Rice
- Department of Anatomy and Neurobiology, Med Sci I, Zot: 4475, University of California, Irvine, Irvine, California 92697-4475, USA
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86
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Tiba PA, Oliveira MGDM, Rossi VC, Tufik S, Suchecki D. Glucocorticoids are not responsible for paradoxical sleep deprivation-induced memory impairments. Sleep 2008; 31:505-15. [PMID: 18457238 DOI: 10.1093/sleep/31.4.505] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
STUDY OBJECTIVES To evaluate whether paradoxical sleep deprivation-induced memory impairments are due to release of glucocorticoids, by means of corticosterone inhibition with metyrapone. DESIGN The design was a 2 (Groups [control, paradoxical sleep-deprived]) x 2 (Treatments [vehicle, metyrapone]) study, performed in 2 experiments: Acute treatment (single injection given immediately after 96 hours of sleep deprivation) and chronic treatment (8 injections, twice per day, throughout the sleep-deprivation period). Animals were either paradoxical sleep-deprived or remained in their home cages for 96 hours before training in contextual fear conditioning and received intraperitoneal injections of a corticosterone synthesis inhibitor, metyrapone. Memory performance was tested 24 hours after training. SUBJECTS Three-month old Wistar male rats. MEASUREMENTS Freezing behavior was considered as the conditioning index, and adrenocorticotropic hormone and corticosterone plasma levels were determined from trunk blood of animals sacrificed in different time points. Animals were weighed before and after the paradoxical sleep-deprivation period. RESULTS Acute metyrapone treatment impaired memory in control animals and did not prevent paradoxical sleep deprivation-induced memory impairment. Likewise, in the chronic treatment, paradoxical sleep-deprived animals did not differ from control rats in their corticosterone or adrenocorticotropic hormone response to training, but still did not learn as well, and did not show any stress responses to the testing. Chronic metyrapone was, however, effective in preventing the weight loss typically observed in paradoxical sleep-deprived animals. CONCLUSIONS Our results suggest that glucocorticoids do not mediate memory impairments but might be responsible for the weight loss induced by paradoxical sleep deprivation.
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Affiliation(s)
- Paula Ayako Tiba
- Department of Psychobiology, Universidade Federal de São Paulo, São Paulo, Brazil
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87
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Stamatakis A, Pondiki S, Kitraki E, Diamantopoulou A, Panagiotaropoulos T, Raftogianni A, Stylianopoulou F. Effect of neonatal handling on adult rat spatial learning and memory following acute stress. Stress 2008; 11:148-59. [PMID: 18311603 DOI: 10.1080/10253890701653039] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
Brief neonatal handling permanently alters hypothalamic-pituitary-adrenal axis function resulting in increased ability to cope with stress. Since stress is known to affect cognitive abilities, in the present study we investigated the effect of brief (15 min) handling on learning and memory in the Morris water maze, following exposure to an acute restraint stress either before training or recall. Exposure of non-handled rats to the acute stress prior to training resulted in quicker learning of the task, than in the absence of the stressor. When acute stress preceded acquisition, male handled rats showed an overall better learning performance, and both sexes of handled animals were less impaired in the subsequent memory trial, compared to the respective non-handled. In addition, the number of neurons immunoreactive for GR was higher in all areas of Ammon's horn of the handled rats during the recall. In contrast, the number of neurons immunoreactive for MR was higher in the CA1 and CA2 areas of the non-handled males. When the acute restraint stress was applied prior to the memory test, neonatal handling was not effective in preventing mnemonic impairment, as all animal groups showed a similar deficit in recall. In this case, no difference between handled and non-handled rats was observed in the number of GR positive neurons in the CA2 and CA3 hippocampal areas during the memory test. These results indicate that early experience interacts with sex and acute stress exposure in adulthood to affect performance in the water maze. Hippocampal corticosterone receptors may play a role in determining the final outcome.
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Affiliation(s)
- A Stamatakis
- Laboratory of Biology-Biochemistry, Faculty of Nursing, School of Health Sciences, University of Athens, Athens, Greece
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88
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Korbey SM, Heinrichs SC, Leussis MP. Seizure susceptibility and locus ceruleus activation are reduced following environmental enrichment in an animal model of epilepsy. Epilepsy Behav 2008; 12:30-8. [PMID: 17983840 DOI: 10.1016/j.yebeh.2007.09.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2007] [Revised: 09/12/2007] [Accepted: 09/14/2007] [Indexed: 11/28/2022]
Abstract
Alterations in the complexity of social and physical housing environments modulate seizure susceptibility in animal models of epilepsy. The studies described here tested the hypothesis that environmental enrichment would delay seizure onset in the epileptic (El) mouse. Neural activation measured via cFos expression, accumulation of the stress neuropeptide corticotropin-releasing factor (CRF), and behavioral seizure susceptibility were quantified in El mice to better understand the mechanisms of ictogenesis. Enrichment housing of El mice from Postnatal Days 21 to 49 produced a 100% decrease in seizure susceptibility relative to El controls. cFos expression increased in the primary motor cortex, locus ceruleus, and hippocampus of El mice relative to ddY controls, an effect attenuated by enrichment housing. CRF levels were elevated by enrichment in the hippocampus of ddY mice only. This study provides evidence that enrichment housing delays the onset of seizure susceptibility in El mice while altering the neuronal and stress-related responses in seizure-associated regions of the El brain.
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Affiliation(s)
- Samantha M Korbey
- Department of Psychology, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467, USA
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89
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Garoflos E, Stamatakis A, Pondiki S, Apostolou A, Philippidis H, Stylianopoulou F. Cellular mechanisms underlying the effect of a single exposure to neonatal handling on neurotrophin-3 in the brain of 1-day-old rats. Neuroscience 2007; 148:349-58. [PMID: 17683871 DOI: 10.1016/j.neuroscience.2007.06.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Revised: 06/13/2007] [Accepted: 06/18/2007] [Indexed: 11/16/2022]
Abstract
Neurotrophin-3 (NT-3) has an important role in brain development and is thus a good candidate molecule to be involved in the cellular mechanisms mediating the effects of early experiences on the brain. In the present work we employed the model of neonatal handling, which is known to affect the ability of the adult organism to respond to stressful stimuli, and determined its effects on NT-3 levels in the rat hippocampus and cortex 2, 4 and 8 h after handling on postnatal day 1. We also recorded maternal behavior during the 8 h following handling. At both the 4 and 8 h time-points there was an increase in NT-3 positive cells in field 1 of Ammon's horn (CA1 area of the hippocampus) and parietal cortex of the handled animals. In the parietal cortex NT-3 levels increased with time following handling: at 8 h there were more NT-3 positive cells than at 4 h. During the 4 h following the end of handling, handled pups were subject to more maternal licking, indicating that the more intense maternal care could underlie the handling-induced increase in NT-3. In the hippocampus, the handling induced increase in NT-3 was cancelled by inhibition of N-methyl-D-aspartate (NMDA), AMPA/kainate, or GABA-A receptors, as well as L-type voltage-gated Ca(2+) channels. It thus appears that neonatal handling activates these neurotransmitter receptors and channels, leading to increased intracellular Ca(2+) and increased NT-3 expression. NT-3 can then activate downstream effectors and exert its morphogenetic actions and thus imprint the effects of handling on the brain.
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Affiliation(s)
- E Garoflos
- Laboratory of Biology-Biochemistry, School of Health Sciences, University of Athens, Papadiamantopoulou 123, GR-11527, Athens, Greece
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90
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Bilbo SD, Newsum NJ, Sprunger DB, Watkins LR, Rudy JW, Maier SF. Differential effects of neonatal handling on early life infection-induced alterations in cognition in adulthood. Brain Behav Immun 2007; 21:332-42. [PMID: 17126527 DOI: 10.1016/j.bbi.2006.10.005] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2006] [Revised: 10/06/2006] [Accepted: 10/06/2006] [Indexed: 10/23/2022] Open
Abstract
We have previously demonstrated that bacterial infection (Escherichia coli) in neonatal rats is associated with impaired memory in a fear-conditioning task in adulthood. This impairment, however, is only observed if a peripheral immune challenge (lipopolysaccharide; LPS) is administered around the time of learning. We used a brief separation/handling paradigm to determine if the adult memory impairment associated with neonatal-infection could be prevented. Naturally occurring variations in maternal care promote striking variations in offspring cognitive development, and handling paradigms are used to manipulate the quality and quantity of maternal care. Rats were injected on post natal (P) day 4 with E. coli or PBS, and half from each group were handled for 15 min/day from P4 to 20. All rats were then tested in adulthood. Neonatal handling of rats infected as neonates prevented the increase in microglial cell marker reactivity within the hippocampus, and the exaggerated brain IL-1beta production to LPS normally produced by the infection. Thus, these neural processes were now comparable to levels of non-infected PBS controls. Furthermore, handling completely prevented LPS-induced memory impairment in a context-fear task in adult rats infected as neonates. Finally, neonatal handling dramatically improved spatial learning and memory and decreased anxiety in rats treated early with PBS, but had no beneficial effect on these measures in rats infected as neonates. Taken together, these data suggest that maternal care may profoundly influence neuroinflammatory processes in adulthood, and that infection may also prevent maternal care influences on cognition later in life.
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Affiliation(s)
- Staci D Bilbo
- Department of Psychology, Center for Neuroscience, University of Colorado, Campus Box 345, Boulder, CO 80309-0345, USA.
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91
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Fenoglio KA, Brunson KL, Baram TZ. Hippocampal neuroplasticity induced by early-life stress: functional and molecular aspects. Front Neuroendocrinol 2006; 27:180-92. [PMID: 16603235 PMCID: PMC2937188 DOI: 10.1016/j.yfrne.2006.02.001] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2005] [Revised: 02/11/2006] [Accepted: 02/13/2006] [Indexed: 12/16/2022]
Abstract
Whereas genetic factors contribute crucially to brain function, early-life events, including stress, exert long-lasting influence on neuronal function. Here, we focus on the hippocampus as the target of these early-life events because of its crucial role in learning and memory. Using a novel immature-rodent model, we describe the deleterious consequences of chronic early-life 'psychological' stress on hippocampus-dependent cognitive tasks. We review the cellular mechanisms involved and discuss the roles of stress-mediating molecules, including corticotropin releasing hormone, in the process by which stress impacts the structure and function of hippocampal neurons.
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Affiliation(s)
- Kristina A. Fenoglio
- Department of Anatomy/Neurobiology, University of California at Irvine, Irvine, CA 92697-4475, USA
| | - Kristen L. Brunson
- Department of Anatomy/Neurobiology, University of California at Irvine, Irvine, CA 92697-4475, USA
| | - Tallie Z. Baram
- Department of Anatomy/Neurobiology, University of California at Irvine, Irvine, CA 92697-4475, USA
- Department of Pediatrics, University of California at Irvine, Irvine, CA 92697-4475, USA
- Corresponding author. Fax: +1 949 824 1106. (T.Z. Baram)
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92
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Fenoglio KA, Chen Y, Baram TZ. Neuroplasticity of the hypothalamic-pituitary-adrenal axis early in life requires recurrent recruitment of stress-regulating brain regions. J Neurosci 2006; 26:2434-42. [PMID: 16510721 PMCID: PMC2408688 DOI: 10.1523/jneurosci.4080-05.2006] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
An eloquent example of experience-induced neuroplasticity involves the enduring effects of daily "handling" of rat pups on the expression of genes regulating hormonal and behavioral responses to stress. Handling-evoked augmentation of maternal care of pups induces long-lasting reduction of hypothalamic corticotropin releasing hormone (CRH) expression and upregulates hippocampal glucocorticoid receptor levels. These changes promote a lifelong attenuation of hormonal stress responses. We have found previously that handling-evoked downregulation of CRH expression occurs already by postnatal day 9, implicating it as an early step in this experience-induced neuroplasticity. Here, we investigated the neuronal pathways and cellular mechanisms involved. CRH mRNA expression in hypothalamic paraventricular nucleus (PVN) diminished after daily handling but not after handling once only, indicating that "recurrent" handling was required for this effect. Return of handled pups to their cage provoked a burst of nurturing behavior in dams that, in turn, induced transient, coordinate Fos expression in selected regions of the pups' brains. These included central nucleus of the amygdala (ACe) and bed nucleus of the stria terminals (BnST), regions that are afferent to PVN and influence CRH expression there. Whereas handling once sufficed to evoke Fos expression within ACe and BnST, expression in thalamic paraventricular nucleus, a region involved in storing and processing stress-related experience, required recurrent handling. Fos induction in all three regions elicited reduced transcription factor phosphorylation, followed by attenuated activation of CRH gene transcription within the PVN. These studies provide a neurobiological foundation for the profound neuroplasticity of stress-related genes evoked by early-life experience.
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93
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Warnock G, Prickaerts J, Steckler T. Interactions between CRF and acetylcholine in the modulation of cognitive behaviour. EXS 2006; 98:41-63. [PMID: 17019882 DOI: 10.1007/978-3-7643-7772-4_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Affiliation(s)
- Geoff Warnock
- Dept. Psychiatry, RED Europe, Johnson and Johnson Pharmaceutical Research and Development, Turnhoutseweg 30, 2340 Beerse, Belgium.
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