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Amini-Khoei H, Mohammadi-Asl A, Amiri S, Hosseini MJ, Momeny M, Hassanipour M, Rastegar M, Haj-Mirzaian A, Mirzaian AH, Sanjarimoghaddam H, Mehr SE, Dehpour AR. Oxytocin mitigated the depressive-like behaviors of maternal separation stress through modulating mitochondrial function and neuroinflammation. Prog Neuropsychopharmacol Biol Psychiatry 2017; 76:169-178. [PMID: 28259722 DOI: 10.1016/j.pnpbp.2017.02.022] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 02/25/2017] [Accepted: 02/28/2017] [Indexed: 02/07/2023]
Abstract
Mother-infant contact has a critical role on brain development and behavior. Experiencing early-life adversities (such as maternal separation stress or MS in rodents) results in adaptations of neurotransmission systems, which may subsequently increase the risk of depression symptoms later in life. In this study, we show that Oxytocin (OT) exerted antioxidant and anti-inflammatory properties. Previous studies indicate that neuroinflammation and mitochondrial dysfunction are associated with the pathophysiology of depression. To investigate the antidepressant-like effects of OT, we applied MS paradigm (as a valid animal model of depression) to male mice at postnatal day (PND) 2 to PND 14 (3h daily, 9AM to 12AM) and investigated the depressive-like behaviors of these animals at PND 60 in different groups. Animals in this work were divided into 4 experimental groups: 1) saline-treated, 2) OT-treated, 3) atosiban (OT antagonist)-treated and, 4) OT+ atosiban-treated mice. We used forced swimming test (FST), splash test, sucrose preference test (SPT) and open field test (OFT) for behavioral assessment. Additionally, we used another set of animals to investigate the effects of MS and different treatments on mitochondrial function and the expression of the relevant genes for neuroinflammation. Our results showed that MS provoked depressive- like behaviors in the FST, SPT and splash test. In addition, our molecular findings revealed that MS is capable of inducing abnormal mitochondrial function and immune-inflammatory response in the hippocampus. Further, we observed that treating stressed animals with OT (intracerebroventricular, i.c.v. injection) attenuated the MS-induced depressive-like behaviors through improving mitochondrial function and decreasing the hippocampal expression of immune-inflammatory genes. In conclusion, we showed that MS-induced depressive-like behaviors in adult male mice are associated with abnormal mitochondrial function and immune-inflammatory responses in the hippocampus, and activation of OTergic system has protective effects against negative effects of MS on brain and behavior of animals.
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Affiliation(s)
- Hossein Amini-Khoei
- Medical Plants Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran; Department of Physiology and Pharmacology, School of Medicine, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Ali Mohammadi-Asl
- Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran, Iran; Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Shayan Amiri
- Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran, Iran; Regenerative Medicine Program, Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Mir-Jamal Hosseini
- Zanjan Applied Pharmacology Research Center, Zanjan University of Medical sciences, Zanjan, Iran; Department of Pharmacology and Toxicology, School of Pharmacy, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Majid Momeny
- Hematology/Oncology and Stem Cell Transplantation Research Center, Shariati Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Mahsa Hassanipour
- Department of Physiology and Pharmacology, School of Medicine, Rafsanjan University of Medical Sciences, Kerman, Iran; Physiology-Pharmacology Research Center, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
| | - Mojgan Rastegar
- Regenerative Medicine Program, Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Arya Haj-Mirzaian
- Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran, Iran; Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Arvin Haj- Mirzaian
- Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran, Iran; Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Shahram Ejtemaei Mehr
- Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran, Iran; Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Ahmad Reza Dehpour
- Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran, Iran; Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
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McCrory EJ, Gerin MI, Viding E. Annual Research Review: Childhood maltreatment, latent vulnerability and the shift to preventative psychiatry - the contribution of functional brain imaging. J Child Psychol Psychiatry 2017; 58:338-357. [PMID: 28295339 PMCID: PMC6849838 DOI: 10.1111/jcpp.12713] [Citation(s) in RCA: 197] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/31/2017] [Indexed: 12/16/2022]
Abstract
BACKGROUND Childhood maltreatment is a potent predictor of poor mental health across the life span. We argue that there is a need to improve the understanding of the mechanisms that confer psychiatric vulnerability following maltreatment, if we are to progress from simply treating those with a manifest disorder, to developing effective preventative approaches that can help offset the likelihood that such disorders will emerge in the first place. METHODS We review extant functional neuroimaging studies of children and adolescents exposed to early neglect and/or maltreatment, including physical, sexual and emotional abuse across four neurocognitive domains: threat processing, reward processing, emotion regulation and executive control. Findings are discussed in the context of 'latent vulnerability', where alterations in neurocognitive function are considered to carry adaptive value in early adverse caregiving environments but confer long-term risk. RESULTS Studies on threat processing indicate heightened as well as depressed neural responsiveness in maltreated samples, particularly in the amygdala, thought to reflect threat hypervigilance and avoidance respectively. Studies on reward processing generally report blunted neural response to anticipation and receipt of rewards, particularly in the striatum, patterns associated with depressive symptomatology. Studies on emotion regulation report increased activation of the anterior cingulate cortex (ACC) during active emotion regulation, possibly reflecting greater effortful processing. Finally, studies of executive control report increased dorsal ACC activity during error monitoring and inhibition. CONCLUSIONS An emerging body of work indicates that altered neurocognitive functioning following maltreatment: (a) is evident even in the absence of overt psychopathology; (b) is consistent with perturbations seen in individuals presenting with psychiatric disorder; (c) can predict future psychiatric symptomatology. These findings suggest that maltreatment leads to neurocognitive alterations that embed latent vulnerability to psychiatric disorder, establishing a compelling case for identifying those children at most risk and developing mechanistically informed models of preventative intervention. Such interventions should aim to offset the likelihood of any future psychiatric disorder.
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Affiliation(s)
- Eamon J. McCrory
- Division of Psychology and Language SciencesUniversity College LondonLondonUK,Anna Freud National Centre for Children and FamiliesLondonUK
| | - Mattia I. Gerin
- Division of Psychology and Language SciencesUniversity College LondonLondonUK,Anna Freud National Centre for Children and FamiliesLondonUK
| | - Essi Viding
- Division of Psychology and Language SciencesUniversity College LondonLondonUK
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Reduced Ventral Tegmental Area-Hippocampal Connectivity in Children and Adolescents Exposed to Early Threat. BIOLOGICAL PSYCHIATRY: COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2017; 2:130-137. [PMID: 28740870 DOI: 10.1016/j.bpsc.2016.11.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Preclinical data suggest that early life stress has detrimental effects on the brain's dopaminergic system, particularly the mesocorticolimbic pathway. Altered dopamine function is thought to contribute to the development of stress-related pathologies; yet, little is known about the impact of early stress on dopamine systems during childhood and adolescence, when stress-related disorders frequently emerge. Here, we evaluate the impact of early threat exposure (violence, abuse) on functional connectivity of putative dopaminergic midbrain regions, the ventral tegmental area (VTA) and substantia nigra (SN), giving rise to mesocorticolimbic and nigrostriatal pathways, respectively. METHODS Resting-state functional magnetic resonance imaging scans were completed in 43 trauma-exposed and 43 matched comparison youth (ages 7-17). Functional connectivity of the VTA and SN were compared between groups. RESULTS The trauma group demonstrated lower functional connectivity between the VTA and hippocampus. No group differences in SN connectivity were observed. Across all participants, there were age-related decreases in connectivity of both VTA and SN with the hippocampus, suggesting that age-related attenuations in VTA-hippocampal circuitry may be exacerbated in trauma-exposed youth. Higher levels of anxiety symptomology were associated with reduced SN-nucleus accumbens connectivity. CONCLUSIONS Prior research suggests that VTA-hippocampal circuitry is critical for the gating of new information into long-term memory. Lower connectivity in this circuitry suggests a novel mechanism that may serve to adaptively prevent the overwriting of a previously stored trauma memory, but at the same time contribute to the broad range of cognitive and emotional difficulties linked to early stress exposure.
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Xu P, Wang K, Lu C, Dong L, Chen Y, Wang Q, Shi Z, Yang Y, Chen S, Liu X. Effects of the chronic restraint stress induced depression on reward-related learning in rats. Behav Brain Res 2017; 321:185-192. [DOI: 10.1016/j.bbr.2016.12.045] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 12/25/2016] [Accepted: 12/29/2016] [Indexed: 12/16/2022]
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Di Liberto V, Frinchi M, Verdi V, Vitale A, Plescia F, Cannizzaro C, Massenti MF, Belluardo N, Mudò G. Anxiolytic effects of muscarinic acetylcholine receptors agonist oxotremorine in chronically stressed rats and related changes in BDNF and FGF2 levels in the hippocampus and prefrontal cortex. Psychopharmacology (Berl) 2017; 234:559-573. [PMID: 27957715 DOI: 10.1007/s00213-016-4498-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 11/16/2016] [Indexed: 12/13/2022]
Abstract
RATIONALE In depressive disorders, one of the mechanisms proposed for antidepressant drugs is the enhancement of synaptic plasticity in the hippocampus and cerebral cortex. Previously, we showed that the muscarinic acetylcholine receptor (mAChR) agonist oxotremorine (Oxo) increases neuronal plasticity in hippocampal neurons via FGFR1 transactivation. OBJECTIVES Here, we aimed to explore (a) whether Oxo exerts anxiolytic effect in the rat model of anxiety-depression-like behavior induced by chronic restraint stress (CRS), and (b) if the anxiolytic effect of Oxo is associated with the modulation of neurotrophic factors, brain-derived neurotrophic factor (BDNF) and fibroblast growth factor-2 (FGF2), and phosphorylated Erk1/2 (p-Erk1/2) levels in the dorsal or ventral hippocampus and in the medial prefrontal cortex. METHODS The rats were randomly divided into four groups: control unstressed, CRS group, CRS group treated with 0.2 mg/kg Oxo, and unstressed group treated with Oxo. After 21 days of CRS, the groups were treated for 10 days with Oxo or saline. The anxiolytic role of Oxo was tested by using the following: forced swimming test, novelty suppressed feeding test, elevated plus maze test, and light/dark box test. The hippocampi and prefrontal cortex were used to evaluate BDNF and FGF2 protein levels and p-Erk1/2 levels. RESULTS Oxo treatment significantly attenuated anxiety induced by CRS. Moreover, Oxo treatment counteracted the CRS-induced reduction of BDNF and FGF2 levels in the ventral hippocampus and medial prefrontal cerebral cortex CONCLUSIONS: The present study showed that Oxo treatment ameliorates the stress-induced anxiety-like behavior and rescues FGF2 and BDNF levels in two brain regions involved in CRS-induced anxiety, ventral hippocampal formation, and medial prefrontal cortex.
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Affiliation(s)
- Valentina Di Liberto
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Corso Tukory 129, 90134, Palermo, Italy
| | - Monica Frinchi
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Corso Tukory 129, 90134, Palermo, Italy
| | - Vincenzo Verdi
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Corso Tukory 129, 90134, Palermo, Italy
| | - Angela Vitale
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Corso Tukory 129, 90134, Palermo, Italy
| | - Fulvio Plescia
- Department of Sciences for Health Promotion and Mother and Child Care "Giuseppe D'Alessandro", University of Palermo, 90134, Palermo, Italy
| | - Carla Cannizzaro
- Department of Sciences for Health Promotion and Mother and Child Care "Giuseppe D'Alessandro", University of Palermo, 90134, Palermo, Italy
| | - Maria F Massenti
- Department of Sciences for Health Promotion and Mother and Child Care "Giuseppe D'Alessandro", University of Palermo, 90134, Palermo, Italy
| | - Natale Belluardo
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Corso Tukory 129, 90134, Palermo, Italy
| | - Giuseppa Mudò
- Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Corso Tukory 129, 90134, Palermo, Italy.
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Psychoneuroimmunology of Early-Life Stress: The Hidden Wounds of Childhood Trauma? Neuropsychopharmacology 2017; 42:99-114. [PMID: 27629365 PMCID: PMC5143500 DOI: 10.1038/npp.2016.198] [Citation(s) in RCA: 216] [Impact Index Per Article: 30.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 09/04/2016] [Accepted: 09/08/2016] [Indexed: 12/15/2022]
Abstract
The brain and the immune system are not fully formed at birth, but rather continue to mature in response to the postnatal environment. The two-way interaction between the brain and the immune system makes it possible for childhood psychosocial stressors to affect immune system development, which in turn can affect brain development and its long-term functioning. Drawing from experimental animal models and observational human studies, we propose that the psychoneuroimmunology of early-life stress can offer an innovative framework to understand and treat psychopathology linked to childhood trauma. Early-life stress predicts later inflammation, and there are striking analogies between the neurobiological correlates of early-life stress and of inflammation. Furthermore, there are overlapping trans-diagnostic patterns of association of childhood trauma and inflammation with clinical outcomes. These findings suggest new strategies to remediate the effect of childhood trauma before the onset of clinical symptoms, such as anti-inflammatory interventions and potentiation of adaptive immunity. Similar strategies might be used to ameliorate the unfavorable treatment response described in psychiatric patients with a history of childhood trauma.
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Robbins TW. Neurobehavioural sequelae of social deprivation in rodents revisited: Modelling social adversity for developmental neuropsychiatric disorders. J Psychopharmacol 2016; 30:1082-1089. [PMID: 27678088 DOI: 10.1177/0269881116664450] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The significance of investigating effects of deprivation of social experience in rodents is reviewed in the context of the review by Robbins et al. (1996) in the Journal of Psychopharmacology (10: 39-47). The early development of the paradigm by which rats were reared post-weaning in social isolation is described and compared with other early experience manipulations. The specification of the neural and behavioural phenotype of the isolate is brought up-to-date, focusing on changes in motivation and cognitive function, as well as on contrasting changes in the dopamine and serotonin systems, and in cortical (including hippocampal) structure and function. The relevance of the isolate for animal models of psychiatric disorders such as attention deficit hyperactivity disorder and schizophrenia is reviewed, and it is considered that the paradigm best exemplifies a manipulation that can be applied to test effects of certain forms of social adversity during adolescence on brain development and behaviour.
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Affiliation(s)
- T W Robbins
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
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Ellenbroek BA, Angelucci F, Husum H, Mathé AA. Gene-environment interactions in a rat model of depression. Maternal separation affects neurotensin in selected brain regions. Neuropeptides 2016; 59:83-88. [PMID: 27372546 DOI: 10.1016/j.npep.2016.05.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 04/13/2016] [Accepted: 05/23/2016] [Indexed: 12/11/2022]
Abstract
Although the etiology of major psychiatric disorders has not been elucidated, accumulating evidence indicates that both genetic and early environmental factors play a role. We have previously demonstrated behavioral and neurochemical changes both in non-manipulated genetic rat models of depression, such as Flinders Sensitive Line (FSL) and Fawn Hooded (FH), and in normal rats following maternal separation (MS). The aim of the present study was to extend this work by exploring whether neurotensin (NT), a peptide implicated in several psychiatric disorders, is altered in a new animal model based on gene - environment interactions. More specifically, we used the FSL rats as a genetic model of depression and the Flinders Resistant Line (FRL) as controls and subjected them to MS. Pups randomly assigned to the MS procedure were separated from the dam as a litter for 180min daily between postnatal day 2 to 14. On postnatal day 90, rats were weighed and sacrificed by a two second high energy focused microwave irradiation and several brain regions were obtained by micropuncture. Neurotensin-like immunoreactivity (NT-LI) was measured by radioimmunoassay (RIA). The results showed that the FSL rats compared to the FRL rats have higher baseline NT-LI concentrations in the temporal cortex and periaqueductal gray and a markedly different response to maternal separation. The only observed change following maternal separation in the FRL rats was an NT-LI increase in the periaqueductal gray. In contrast, in the FSL significant increases were found in the nucleus accumbens, hippocampus, and entorhinal cortex and a decrease was seen in the temporal cortex after MS. The present study revealed baseline regional differences in NT-LI concentrations between the FSL and FRL strains and demonstrated that early MD differentially affects the two strains. The relevance of these alterations for depression as well as possible mechanisms underlying this gene-environment interaction are discussed.
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Affiliation(s)
- Bart A Ellenbroek
- School of Psychology, Victoria University of Wellington, Wellington, New Zealand.
| | | | - Henriette Husum
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Aleksander A Mathé
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Danese A, Baldwin JR. Hidden Wounds? Inflammatory Links Between Childhood Trauma and Psychopathology. Annu Rev Psychol 2016; 68:517-544. [PMID: 27575032 DOI: 10.1146/annurev-psych-010416-044208] [Citation(s) in RCA: 136] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Childhood trauma is a key risk factor for psychopathology. However, little is known about how exposure to childhood trauma is translated into biological risk for psychopathology. Observational human studies and experimental animal models suggest that childhood exposure to stress can trigger an enduring systemic inflammatory response not unlike the bodily response to physical injury. In turn, these "hidden wounds" of childhood trauma can affect brain development, key behavioral domains (e.g., cognition, positive valence systems, negative valence systems), reactivity to subsequent stressors, and, ultimately, risk for psychopathology. Further research is needed to better characterize the inflammatory links between childhood trauma and psychopathology. Detecting and healing these hidden wounds may help prevent and treat psychopathology emerging after childhood trauma.
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Affiliation(s)
- Andrea Danese
- MRC Social, Genetic, and Developmental Psychiatry Research Centre, Institute of Psychiatry, Psychology and Neuroscience, Kings College London, London SE5 8AF, United Kingdom; .,Department of Child and Adolescent Psychiatry, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 8AF, United Kingdom.,National and Specialist Clinic for Child Traumatic Stress and Anxiety Disorders, South London and Maudsley NHS Foundation Trust, London SE5 8AZ, United Kingdom
| | - Jessie R Baldwin
- MRC Social, Genetic, and Developmental Psychiatry Research Centre, Institute of Psychiatry, Psychology and Neuroscience, Kings College London, London SE5 8AF, United Kingdom;
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Nusslock R, Miller GE. Early-Life Adversity and Physical and Emotional Health Across the Lifespan: A Neuroimmune Network Hypothesis. Biol Psychiatry 2016; 80:23-32. [PMID: 26166230 PMCID: PMC4670279 DOI: 10.1016/j.biopsych.2015.05.017] [Citation(s) in RCA: 376] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2015] [Revised: 05/07/2015] [Accepted: 05/26/2015] [Indexed: 12/29/2022]
Abstract
Children who experience chronic stressors are vulnerable to emotional and physical health problems across the lifespan. This phenomenon raises questions for scientists and clinicians alike. How does adversity get under the skin of the developing child? Through what mechanisms does it confer vulnerability to a heterogeneous set of mental and physical illnesses? And how does it instantiate risk across different life stages, engendering vulnerability to conditions that develop shortly after stressor exposure-like depression-and conditions that manifest decades later, like heart disease? Although answers to these questions have started to emerge, research has typically focused on single diseases or organ systems. To understand the plethora of health problems associated with childhood adversity, we argue that the field needs a second generation of research that recognizes multidirectional transactions among biological systems. To help facilitate this process, we propose a neuroimmune network hypothesis as a heuristic framework for organizing knowledge from disparate literatures and as a springboard for generating integrative research. Drawing on existing data, we argue that early-life adversity amplifies crosstalk between peripheral inflammation and neural circuitries subserving threat-related, reward-related, and executive control-related processes. This crosstalk results in chronic low-grade inflammation, thereby contributing to adiposity, insulin resistance, and other predisease states. In the brain, inflammatory mediators act on cortico-amygdala threat and cortico-basal ganglia reward, circuitries in a manner that predisposes individuals to self-medicating behaviors like smoking, drug use, and consumption of high-fat diets. Acting in concert with inflammation, these behaviors accelerate the pathogenesis of emotional and physical health problems.
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Affiliation(s)
| | - Gregory E. Miller
- Department of Psychology, Northwestern University,Institute for Policy Research, Northwestern University
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Multilevel developmental approaches to understanding the effects of child maltreatment: Recent advances and future challenges. Dev Psychopathol 2016; 27:1387-97. [PMID: 26535932 DOI: 10.1017/s0954579415000826] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Recent research in the field of child maltreatment has begun to shed new light on the emergence of health problems in children by emphasizing the responsiveness of developmental processes to children's environmental and biological contexts. Here, I highlight recent trends in the field with an emphasis on the effects of early life stress across multiple levels of developmental domains.
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Fareri DS, Tottenham N. Effects of early life stress on amygdala and striatal development. Dev Cogn Neurosci 2016; 19:233-47. [PMID: 27174149 PMCID: PMC4912892 DOI: 10.1016/j.dcn.2016.04.005] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 03/28/2016] [Accepted: 04/27/2016] [Indexed: 12/13/2022] Open
Abstract
Species-expected caregiving early in life is critical for the normative development and regulation of emotional behavior, the ability to effectively evaluate affective stimuli in the environment, and the ability to sustain social relationships. Severe psychosocial stressors early in life (early life stress; ELS) in the form of the absence of species expected caregiving (i.e., caregiver deprivation), can drastically impact one's social and emotional success, leading to the onset of internalizing illness later in life. Development of the amygdala and striatum, two key regions supporting affective valuation and learning, is significantly affected by ELS, and their altered developmental trajectories have important implications for cognitive, behavioral and socioemotional development. However, an understanding of the impact of ELS on the development of functional interactions between these regions and subsequent behavioral effects is lacking. In this review, we highlight the roles of the amygdala and striatum in affective valuation and learning in maturity and across development. We discuss their function separately as well as their interaction. We highlight evidence across species characterizing how ELS induced changes in the development of the amygdala and striatum mediate subsequent behavioral changes associated with internalizing illness, positing a particular import of the effect of ELS on their interaction.
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Affiliation(s)
- Dominic S Fareri
- Gordon F. Derner Institute for Advanced Psychological Studies, Adelphi University, Garden City, NY 11530, United States.
| | - Nim Tottenham
- Department of Psychology, Columbia University, New York, NY 10027, United States
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Exposure to early adversity: Points of cross-species translation that can lead to improved understanding of depression. Dev Psychopathol 2016; 27:477-91. [PMID: 25997766 DOI: 10.1017/s0954579415000103] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The relationship between developmental exposure to adversity and affective disorders is reviewed. Adversity discussed herein includes physical and sexual abuse, neglect, or loss of a caregiver in humans. While these stressors can occur at any point during development, the unique temporal relationship to specific depressive symptoms was the focus of discussion. Further influences of stress exposure during sensitive periods can vary by gender and duration of abuse as well. Data from animal studies are presented to provide greater translational and causal understanding of how sensitive periods, different types of psychosocial stressors, and sex interact to produce depressive-like behaviors. Findings from maternal separation, isolation rearing, chronic variable stress, and peer-peer rearing paradigms clarify interpretation about how various depressive behaviors are influenced by age of exposure. Depressive behaviors are broken down into the following categories: mood and affect, anhedonia, energy, working memory, sleep-wake, appetite changes, suicide, and general malaise. Cross-species evidence from humans, nonhuman primates, rats, and mice within each of these categories is discussed. In conclusion, sensitive periods for affective-related behaviors (anxiety, mood, and controllability) occur earlier in life, while other aspects of depression are associated with adversity later during adolescence.
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64
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Ragan CM, Harding KM, Lonstein JS. Associations among within-litter differences in early mothering received and later emotional behaviors, mothering, and cortical tryptophan hydroxylase-2 expression in female laboratory rats. Horm Behav 2016; 77:62-71. [PMID: 26219576 PMCID: PMC7005883 DOI: 10.1016/j.yhbeh.2015.07.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 07/20/2015] [Accepted: 07/22/2015] [Indexed: 12/25/2022]
Abstract
This article is part of a Special Issue "Parental Care". The effects of differential maternal care received on offspring phenotype in rodents has been extensively studied between litters, but the consequences of differential mothering within litters on offspring neurobehavioral development have been rarely examined. We here investigated how variability in maternal care received among female rat siblings (measured four times daily on postnatal days 4, 6, 8, and 10) relates to the siblings' later emotional and maternal behaviors. As previously reported, we found that some female pups received up to three times more maternal licking bouts compared to their sisters; this difference was positively correlated with the pups' body weights. The number of maternal licking bouts that females received was negatively correlated with their later neophobic behaviors in an open field during periadolescence, but positively correlated with their anxiety-related behavior in an elevated plus maze during adulthood. Licking received was also positively correlated with females' later likelihood to retrieve pups in a maternal sensitization paradigm. In addition, females' neophobia during adolescence and anxiety-related behavior during adulthood predicted some aspects of both postpartum and sensitized maternal responsiveness. Medial prefrontal cortex expression of tryptophan hydroxylase-2 (TPH2; enzyme necessary for serotonin synthesis) was negatively associated with early maternal licking received. Interestingly, cortical TPH2 was positively associated with the maternal responsiveness of sensitized virgins but negatively associated with it in postpartum females. These results indicate that within-litter differences in maternal care received is an often neglected, but important, contributor to individual differences in offspring socioemotional behaviors as well as to the cortical serotonin neurochemistry that may influence these behaviors.
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Affiliation(s)
- Christina M Ragan
- Department of Psychology and Neuroscience Program, Michigan State University, 108 Giltner Hall, East Lansing, MI 48824, USA.
| | - Kaitlyn M Harding
- Department of Psychology and Neuroscience Program, Michigan State University, 108 Giltner Hall, East Lansing, MI 48824, USA
| | - Joseph S Lonstein
- Department of Psychology and Neuroscience Program, Michigan State University, 108 Giltner Hall, East Lansing, MI 48824, USA
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Lomanowska AM, Melo AI. Deconstructing the function of maternal stimulation in offspring development: Insights from the artificial rearing model in rats. Horm Behav 2016; 77:224-36. [PMID: 26112882 DOI: 10.1016/j.yhbeh.2015.05.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 05/24/2015] [Accepted: 05/28/2015] [Indexed: 10/23/2022]
Abstract
This article is part of a Special Issue on "Parental Care". Maternal behavior has an important function in stimulating adequate growth and development of the young. Several approaches have been used in primates and rodents to deconstruct and examine the influence of specific components of maternal stimulation on offspring development. These approaches include observational studies of typical mother-infant interactions and studies of the effects of intermittent or complete deprivation of maternal contact. In this review, we focus on one unique approach using rats that enables the complete control of maternal variables by means of rearing rat pups artificially without contact with the mother or litter, while maintaining stable nutrition, temperature and exposure to stressful stimuli. This artificial rearing model permits the removal and controlled replacement of relevant maternal and litter stimuli and has contributed valuable insights regarding the influence of these stimuli on various developmental outcomes. It also enables the analysis of factors implicated in social isolation itself and their long-term influence. We provide an overview of the effects of artificial rearing on behavior, physiology, and neurobiology, including the influence of replacing maternal tactile stimulation and littermate contact on these outcomes. We then discuss the relevance of these effects in terms of the maternal role in regulating different aspects of offspring development and implications for human research. We emphasize that artificial rearing of rats does not lead to a global insult of nervous system development, making this paradigm useful in investigating specific developmental effects associated with maternal stimulation.
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Affiliation(s)
- Anna M Lomanowska
- School of Psychology, Laval University, Centre de recherche de l'Institut universitaire en santé mentale de Québec, Quebec City, QC G1J 2G3, Canada
| | - Angel I Melo
- Centro de Investigación en Reproducción Animal, CINVESTAV-Laboratorio Tlaxcala, Universidad Autónoma de Tlaxcala, Apdo Postal 62. C.P. Tlaxcala, Tlax. C.P. 90000, México.
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66
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Shagiakhmetov FS, Proskuryakova TV, Shamakina IY. The dynorphin/kappa-opioid system of the brain as a promising target for therapy for dependence on psychoactive substances. NEUROCHEM J+ 2015. [DOI: 10.1134/s1819712415040157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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67
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Hanson JL, Hariri AR, Williamson DE. Blunted Ventral Striatum Development in Adolescence Reflects Emotional Neglect and Predicts Depressive Symptoms. Biol Psychiatry 2015; 78:598-605. [PMID: 26092778 PMCID: PMC4593720 DOI: 10.1016/j.biopsych.2015.05.010] [Citation(s) in RCA: 207] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 05/08/2015] [Accepted: 05/08/2015] [Indexed: 12/24/2022]
Abstract
BACKGROUND Emotional neglect is associated with multiple negative outcomes, particularly increased risk for depression. Motivated by increasing evidence of reward-related ventral striatum (VS) dysfunction in depression, we investigated the role of developmental changes in VS activity on the emergence of depressive symptomatology as a function of emotional neglect. METHODS We examined relationships between longitudinal neuroimaging of reward-related VS activity, assessments of mood, and measures of emotional neglect in 106 participants first scanned between ages 11 to 15 and then 2 years later. RESULTS We found that greater levels of emotional neglect were associated with blunted development of reward-related VS activity between the first and second assessments (as indexed by lower residualized change scores). Additionally, we found that decreases in this reward-related VS activity were related to greater depressive symptomatology and partially mediated the association between emotional neglect and subsequent depressive symptomatology. CONCLUSIONS Our results provide an important demonstration that blunted development of reward-related VS activity as a function of emotional neglect predicts the emergence of depressive symptoms in adolescents. Further, our results are consistent with emerging evidence for the importance of reward-related VS dysfunction in the etiology and pathophysiology of depression. These results are a first step toward developing the ability to predict, prevent, and treat stress-related psychopathology through the targeting of specific neural phenotypes.
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Affiliation(s)
- Jamie L Hanson
- Department of Psychology and Neuroscience, Durham, North Carolina.
| | - Ahmad R Hariri
- Department of Psychology & Neuroscience, Duke University, 417 Chapel Drive, Duke West Campus, Sociology-Psychology Building, Room 07A, Durham, NC 27710
| | - Douglas E Williamson
- Department of Psychiatry, University of Texas Health Sciences Center at San Antonio,South Texas Veterans Health Care System, 7703 Floyd Curl Drive, San Antonio, TX 78229
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Hanson JL, Albert D, Iselin AMR, Carré JM, Dodge KA, Hariri AR. Cumulative stress in childhood is associated with blunted reward-related brain activity in adulthood. Soc Cogn Affect Neurosci 2015; 11:405-12. [PMID: 26443679 DOI: 10.1093/scan/nsv124] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 09/28/2015] [Indexed: 11/12/2022] Open
Abstract
Early life stress (ELS) is strongly associated with negative outcomes in adulthood, including reduced motivation and increased negative mood. The mechanisms mediating these relations, however, are poorly understood. We examined the relation between exposure to ELS and reward-related brain activity, which is known to predict motivation and mood, at age 26, in a sample followed since kindergarten with annual assessments. Using functional neuroimaging, we assayed individual differences in the activity of the ventral striatum (VS) during the processing of monetary rewards associated with a simple card-guessing task, in a sample of 72 male participants. We examined associations between a cumulative measure of ELS exposure and VS activity in adulthood. We found that greater levels of cumulative stress during childhood and adolescence predicted lower reward-related VS activity in adulthood. Extending this general developmental pattern, we found that exposure to stress early in development (between kindergarten and grade 3) was significantly associated with variability in adult VS activity. Our results provide an important demonstration that cumulative life stress, especially during this childhood period, is associated with blunted reward-related VS activity in adulthood. These differences suggest neurobiological pathways through which a history of ELS may contribute to reduced motivation and increased negative mood.
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Affiliation(s)
- Jamie L Hanson
- Laboratory of NeuroGenetics, Department of Psychology & Neuroscience, Duke University, Durham, NC, USA, Center For Developmental Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA, Center for Child & Family Policy, Duke University, Durham, NC, USA,
| | - Dustin Albert
- Department of Psychology, Bryn Mawr College, Bryn Mawr, PA, USA
| | - Anne-Marie R Iselin
- Department of Psychology, University of North Carolina-Wilmington, Wilmington, NC, USA
| | - Justin M Carré
- Department of Psychology, Nipissing University, North Bay, ON, Canada, and
| | - Kenneth A Dodge
- Center for Child & Family Policy, Duke University, Durham, NC, USA, Sanford School of Public Policy, Duke University, Durham, NC, USA
| | - Ahmad R Hariri
- Laboratory of NeuroGenetics, Department of Psychology & Neuroscience, Duke University, Durham, NC, USA
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Abstract
The integrative field of developmental psychopathology is having a huge impact on our understanding of human health and behavior. In this paper, I use the example of children's early stress exposure to illustrate how developmental psychopathologists now tend to deemphasize diagnostic categories and, instead, emphasize the social and biological contexts, events and circumstances that have created opportunities for maladaptive responses and health problems in youth. This example shows that developmental psychopathology is increasing understanding of how children develop the abilities that allow them to cope effectively with challenges and what leads to failures in development of these abilities. Integrating research about the neurobiology of learning may prove to be a powerful future direction to understand how the environment regulates behavior. Learning processes become increasingly intricate and fine-tuned as relevant neuroanatomical systems develop, and as the range, complexity and amount of environmental information increases for the developing child. A focus on these processes allows psychopathologists to formulate questions about which neural mechanisms children use to process information, how these mechanisms are themselves shaped by social context, why adverse social environments confer risk for children, and, perhaps, what sorts of neutrally informed interventions might remediate the deficits in self-regulation that underlie common psychopathologies.
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Affiliation(s)
- Seth D Pollak
- Department of Psychology, University of Wisconsin-MadisonMadison, WI, 53706, USA
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Enhancing glutamatergic transmission during adolescence reverses early-life stress-induced deficits in the rewarding effects of cocaine in rats. Neuropharmacology 2015; 99:168-76. [PMID: 26187394 DOI: 10.1016/j.neuropharm.2015.07.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 07/06/2015] [Accepted: 07/11/2015] [Indexed: 12/20/2022]
Abstract
Adolescence marks a critical time when the brain is highly susceptible to pathological insult yet also uniquely amenable to therapeutic intervention. It is during adolescence that the onset of the majority of psychiatric disorders, including substance use disorder (SUDs), occurs. It has been well established that stress, particularly during early development, can contribute to the pathological changes which contribute to the development of SUDs. Glutamate as the main excitatory neurotransmitter in the mammalian CNS plays a key role in various physiological processes, including reward function, and in mediating the effects of psychological stress. We hypothesised impairing glutamatergic signalling during the key adolescent period would attenuate early-life stress induced impaired reward function. To test this, we induced early-life stress in male rats using the maternal-separation procedure. During the critical adolescent period (PND25-46) animals were treated with the glutamate transporter activator, riluzole, or the NMDA receptor antagonist, memantine. Adult reward function was assessed using voluntary cocaine intake measured via intravenous self-administration. We found that early-life stress in the form of maternal-separation impaired reward function, reducing the number of successful cocaine-infusions achieved during the intravenous self-administration procedure as well impairing drug-induced reinstatement of cocaine-taking behaviour. Interestingly, riluzole and memantine treatment reversed this stress-induced impairment. These data suggest that reducing glutamatergic signalling may be a viable therapeutic strategy for treating vulnerable individuals at risk of developing SUDs including certain adolescent populations, particularly those which may have experienced trauma during early-life.
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71
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Hodel AS, Brumbaugh JE, Morris AR, Thomas KM. Hot executive function following moderate-to-late preterm birth: altered delay discounting at 4 years of age. Dev Sci 2015; 19:221-34. [PMID: 25873181 DOI: 10.1111/desc.12307] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 02/18/2015] [Indexed: 01/08/2023]
Abstract
Interest in monitoring long-term neurodevelopmental outcomes of children born moderate-to-late preterm (32-36 weeks gestation) is increasing. Moderate-to-late preterm birth has a negative impact on academic achievement, which may relate to differential development of executive function (EF). Prior studies reporting deficits in EF in preterm children have almost exclusively assessed EF in affectively neutral contexts in high-risk preterm children (< 32 weeks gestation). Disrupted function in motivational or emotionally charged contexts (hot EF) following preterm birth remains uninvestigated, despite evidence that preterm children show differential development of neural circuitry subserving hot EF, including reduced orbitofrontal cortex volume. The present study is the first to examine whether low-risk, healthy children born moderate-to-late preterm exhibit impairments in the development of hot EF. Preterm children at age 4.5 years were less likely to choose larger, delayed rewards across all levels of reward magnitude on a delay discounting task using tangible rewards, but performed more similarly to their full-term peers on a delay aversion task involving abstract rewards and on measures of cool EF. The relationship between gestational age at birth and selection of delayed rewards extended across the entire gestational age range of the sample (32-42 weeks), and remained significant after controlling for intelligence and processing speed. Results imply that there is not a finite cut-off point at which children are spared from potential long-term neurodevelopmental effects of PT birth. Further investigation of reward processing and hot EF in individuals with a history of PT birth is warranted given the susceptibility of prefrontal cortex development to early environmental variations.
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Affiliation(s)
- Amanda S Hodel
- Institute of Child Development, University of Minnesota, USA
| | - Jane E Brumbaugh
- Stead Family Department of Pediatrics, University of Iowa Hospitals and Clinics, USA
| | - Alyssa R Morris
- Institute of Child Development, University of Minnesota, USA
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72
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Boku S, Toda H, Nakagawa S, Kato A, Inoue T, Koyama T, Hiroi N, Kusumi I. Neonatal maternal separation alters the capacity of adult neural precursor cells to differentiate into neurons via methylation of retinoic acid receptor gene promoter. Biol Psychiatry 2015; 77:335-44. [PMID: 25127741 PMCID: PMC5241093 DOI: 10.1016/j.biopsych.2014.07.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 07/05/2014] [Accepted: 07/09/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND Early life stress is thought to contribute to psychiatric disorders, but the precise mechanisms underlying this link are poorly understood. As neonatal stress decreases adult hippocampal neurogenesis, which, in turn, functionally contributes to many behavioral phenotypes relevant to psychiatric disorders, we examined how in vivo neonatal maternal separation (NMS) impacts the capacity of adult hippocampal neural precursor cells via epigenetic alterations in vitro. METHODS Rat pups were separated from their dams for 3 hours daily from postnatal day (PND) 2 to PND 14 or were never separated from the dam (as control animals). We isolated adult neural precursor cells from the hippocampal dentate gyrus at PND 56 and assessed rates of proliferation, apoptosis, and differentiation in cell culture. We also evaluated the effect of DNA methylation at the retinoic acid receptor (RAR) promoter stemming from NMS on adult neural precursor cells. RESULTS NMS attenuated neural differentiation of adult neural precursor cells but had no detectible effect on proliferation, apoptosis, or astroglial differentiation. The DNA methyltransferase (DNMT) inhibitor, 5-aza-dC, reversed a reduction by NMS of neural differentiation of adult neural precursor cells. NMS increased DNMT1 expression and decreased expression of RARα. An RARα agonist increased neural differentiation and an antagonist reduced retinoic acid-induced neural differentiation. NMS increased the methylated portion of RARα promoter, and the DNMT inhibitor reversed a reduction by NMS of RARα messenger RNA expression. CONCLUSIONS NMS attenuates the capacity of adult hippocampal neural precursor cells to differentiate into neurons by decreasing expression of RARα through DNMT1-mediated methylation of its promoter.
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Affiliation(s)
- Shuken Boku
- Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, Bronx, New York; Department of Psychiatry, Hokkaido University School of Medicine, Sapporo.
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73
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Réus GZ, Nacif MP, Abelaira HM, Tomaz DB, dos Santos MAB, Carlessi AS, da Luz JR, Gonçalves RC, Vuolo F, Dal-Pizzol F, Carvalho AF, Quevedo J. Ketamine ameliorates depressive-like behaviors and immune alterations in adult rats following maternal deprivation. Neurosci Lett 2015; 584:83-7. [DOI: 10.1016/j.neulet.2014.10.022] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 10/07/2014] [Accepted: 10/10/2014] [Indexed: 12/12/2022]
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Abstract
Depression is a significant public health problem, but its etiology and pathophysiology remain poorly understood. Such incomplete understanding likely arises from the fact that depression encompasses a heterogeneous set of disorders. To overcome these limitations, renewed interest in intermediate phenotypes (endophenotypes) has resurfaced, and anhedonia has emerged as one of the most promising endophenotypes of depression. Here, a heuristic model is presented postulating that anhedonia arises from dysfunctional interactions between stress and brain reward systems. To this end, we review and integrate three bodies of independent literature investigating the role of (a) anhedonia, (b) dopamine, and (c) stress in depression. In a fourth section, we summarize animal data indicating that stress negatively affects mesocorticolimbic dopaminergic pathways critically implicated in incentive motivation and reinforcement learning. In the last section, we provide a synthesis of these four literatures, present initial evidence consistent with our model, and discuss directions for future research.
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Affiliation(s)
- Diego A Pizzagalli
- Department of Psychiatry, Harvard Medical School and McLean Hospital, Belmont, Massachusetts 02478;
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75
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Pearson R, McGeary JE, Beevers CG. Association between serotonin cumulative genetic score and the Behavioral Approach System (BAS): Moderation by early life environment. PERSONALITY AND INDIVIDUAL DIFFERENCES 2014; 70:140-144. [PMID: 25264393 DOI: 10.1016/j.paid.2014.06.041] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The present study investigates if genetic variation in the serotonergic system interacts with early adversity to predict changes in the Behavioral Approach System (BAS), a system that taps into reward processing. In a sample of community adults (N= 236) the influence of single serotonergic candidate polymorphisms on BAS was analyzed, we also examined the aggregate contribution of these genetic variants by creating a Cumulative Genetic Score (CGS). A CGS quantifies an individual's cumulative risk by aggregating the number of risk alleles across the candidate polymorphisms. After individual gene analysis, three candidate genes rs7305115 (TPH2), rs6311 (HTR2A), and rs6295 (HTR1A) were combined into the CGS. There were no significant interactions between individual candidate polymorphisms and childhood adversity, but the CGS interacted with childhood adversity to explain a significant amount of variance (11.6%) in the BAS. Findings suggest that genetic variations in the serotonergic system in combination with childhood adversity contribute to individual differences in reward sensitivity.
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Affiliation(s)
| | - John E McGeary
- Providence Veterans Affairs Medical Center & Alpert Medical School of Brown University
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76
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Vetulani J. Early maternal separation: a rodent model of depression and a prevailing human condition. Pharmacol Rep 2014; 65:1451-61. [PMID: 24552992 DOI: 10.1016/s1734-1140(13)71505-6] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 09/16/2013] [Indexed: 01/28/2023]
Abstract
The early life of most mammals is spent in close contact with the mother, and for the neonate, early maternal separation is a traumatic event that, depending on various conditions, may shape its behavioral and neurochemical phenotype in adulthood. Studies on rodents demonstrated that a very brief separation followed by increased maternal care may positively affect the development of the offspring but that prolonged separation causes significant amounts of stress. The consequences of this stress (particularly the hyperreactivity of the HPA (hypothalamic-pituitary-adrenal) axis are expressed in adulthood and persist for life. Maternal separation in rodents, particularly rats, was used as a model for various psychotic conditions, especially depression. The most popular separation procedure of a 3-h daily separation from the second to the 12th postpartum day yields a depression model of high construct and predictive validity. The results of studies on maternal separation in rats and monkeys prompt a discussion of the consequences of traditional procedures in the maternity wards of developed countries where attention is focused on the hygiene of the neonates and not on their psychological needs. This alternate focus results in a drastic limitation of mother-infant contact and prolonged periods of separation. It is tempting to speculate that differences in the course and severity of various mental disorders, which are usually less prevalent in underdeveloped countries than in developed countries (as noted by Kraepelin), may be related to different modes of infant care. Only recently has so-called kangaroo mother care (establishing mother-infant skin-to-skin contact immediately after birth) become popular in developed countries. In addition to its instant benefits for the neonates, this procedure may also be beneficial for the mental health of the offspring in adulthood.
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Affiliation(s)
- Jerzy Vetulani
- Department of Brain Biochemistry, Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, PL 31-343 Kraków, Poland.
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77
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Melo AI. Role of sensory, social, and hormonal signals from the mother on the development of offspring. ADVANCES IN NEUROBIOLOGY 2014; 10:219-48. [PMID: 25287543 DOI: 10.1007/978-1-4939-1372-5_11] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
For mammals, sensory, social, and hormonal experience early in life is essential for the continuity of the infant's development. These experiences come from the mother through maternal care, and have enduring effects on the physiology and behavior of the adult organism. Disturbing the mother-offspring interaction by maternal deprivation (neglect) or exposure to adverse events as chronic stress, maltreatment, or sexual abuse has negative effects on the mental, psychological, physiological, and behavioral health. Indeed, these kinds of negative experiences can be the source of some neuropsychiatric diseases as depression, anxiety, impulsive aggression, and antisocial behavior. The purpose of this chapter is to review the most relevant evidence that supports the participation of cues from the mother and/or littermates during the postnatal preweaning period for the development of nervous system of the offspring. These findings come from the most frequently utilized experimental paradigms used in animal models, such as natural variations in maternal behavior, handling, partial maternal deprivation, and total maternal deprivation and artificial rearing. Through the use of these experimental procedures, it is possible to positively (handling paradigm), or negatively (maternal deprivation paradigms), affect the offspring's development. Finally, this chapter reviews the importance of the hormones that pups ingest through the maternal milk during early lactation on the development of several physiological systems, including the immune, endocrine systems, as well as on the adult behavior of the offspring.
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Affiliation(s)
- Angel I Melo
- Centro de Investigación en Reproducción Animal, CINVESTAV-Laboratorio Tlaxcala, Universidad Autónoma de Tlaxcala, Tlaxcala, Mexico,
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78
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Morgan JK, Shaw DS, Forbes EE. Fearfulness moderates the link between childhood social withdrawal and adolescent reward response. Soc Cogn Affect Neurosci 2014; 10:761-8. [PMID: 25193948 DOI: 10.1093/scan/nsu113] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 09/01/2014] [Indexed: 11/12/2022] Open
Abstract
Withdrawal from peers during childhood may reflect disruptions in reward functioning that heighten vulnerability to affective disorders during adolescence. The association between socially withdrawn behavior and reward functioning may depend on traits that influence this withdrawal, such as fearfulness or unsociability. In a study of 129 boys, we evaluated how boys' fearfulness and sociability at age 5 and social withdrawal at school at ages 6 to 10 and during a summer camp at age 9/10 were associated with their neural response to reward at age 20. Greater social withdrawal during childhood was associated with heightened striatal and mPFC activation when anticipating rewards at age 20. Fearfulness moderated this effect to indicate that social withdrawal was associated with heightened reward-related response in the striatum for boys high on fearfulness. Altered striatal response associated with social withdrawal and fearfulness predicted greater likelihood to have a lifetime history of depression and social phobia at age 20. These findings add greater specificity to previous findings that children high in traits related to fear of novelty show altered reward responses, by identifying fearfulness (but not low levels of sociability) as a potential underlying mechanism that contributes to reward alterations in withdrawn children.
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Affiliation(s)
- Judith K Morgan
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA and Department of Psychology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Daniel S Shaw
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA and Department of Psychology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Erika E Forbes
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA and Department of Psychology, University of Pittsburgh, Pittsburgh, PA 15213, USA Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA and Department of Psychology, University of Pittsburgh, Pittsburgh, PA 15213, USA
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79
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Increased behavioral output but intact goal-directed and habitual responding for food reward following early-life social deprivation in rats. Behav Brain Res 2014; 271:94-105. [DOI: 10.1016/j.bbr.2014.05.062] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 05/21/2014] [Accepted: 05/27/2014] [Indexed: 11/22/2022]
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Myers B, McLaughlin KA, Wang S, Blanco C, Stein DJ. Associations between childhood adversity, adult stressful life events, and past-year drug use disorders in the National Epidemiological Study of Alcohol and Related Conditions (NESARC). PSYCHOLOGY OF ADDICTIVE BEHAVIORS 2014; 28:1117-26. [PMID: 25134042 DOI: 10.1037/a0037459] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Stress sensitization, whereby CA lowers tolerance to later stressors, has been proposed as a potential mechanism explaining the association between exposure to childhood adversities (CA) and drug use disorders in adulthood. However, this mechanism remains untested. This paper begins to address this gap through exploring associations between CA exposure and stressful events in adulthood for predicting drug use disorders. We used data drawn from Wave 2 of the U.S. National Epidemiological Survey of Alcohol and Related Conditions (n = 34,653) to explore whether the association between past-year stressful life events and the 12-month prevalence of disordered cannabis, stimulant, and opiate use varied by the number of types of CA that an individual was exposed to. Past-year stressful life events were associated with an increased risk of cannabis, stimulant, and opiate use disorders among men and women. Exposure to CA was associated with increased risk for disordered cannabis use among men and women and opiate use among men only. Finally, we found significant associations between exposure to CA and past-year stressful life events in predicting disordered drug use, but only for women in relation to disordered stimulant and opiate use. Findings are suggestive of possible stress sensitization effects in predicting disordered stimulant and opiate use among women. Implications of these findings for the prevention and treatment of drug use disorders and for future research are discussed.
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Affiliation(s)
- Bronwyn Myers
- Alcohol, Tobacco, and Other Drug Research Unit, South African Medical Research Council
| | | | - Shuai Wang
- New York State Psychiatric Institute, Department of Psychiatry, College of Physicians and Surgeons, Columbia University
| | - Carlos Blanco
- New York State Psychiatric Institute, Department of Psychiatry, College of Physicians and Surgeons, Columbia University
| | - Dan J Stein
- Department of Psychiatry and Mental Health, Faculty of Health Sciences, University of Cape Town
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Dimatelis JJ, Russell VA, Stein DJ, Daniels WM. Methamphetamine reversed maternal separation-induced decrease in nerve growth factor in the ventral hippocampus. Metab Brain Dis 2014; 29:433-9. [PMID: 24407463 DOI: 10.1007/s11011-014-9481-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2013] [Accepted: 01/03/2014] [Indexed: 10/25/2022]
Abstract
Stress has been suggested to predispose individuals to drug abuse. The early life stress of maternal separation (MS) is known to alter the response to drugs of abuse later in life. Exposure to either stress or methamphetamine has been shown to alter neurotrophic factors in the brain. Changes in neurotrophin levels may contribute to the underlying molecular mechanisms responsible for drug use- and stress-induced behaviours. The purpose of the present study was to investigate the individual effects of MS and methamphetamine administration during adolescence and the combined effects of both stressors on brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) levels in the dorsal and ventral hippocampus (HC) in adulthood. Methamphetamine administration (1 mg/kg, daily from postnatal day (PND) 33 to 36 and from PND 39 to 42), MS and the combination of the two stressors resulted in decreased BDNF levels in both the dorsal and ventral HC. MS decreased NGF levels in the ventral HC which was restored by methamphetamine administration in adolescence. In the dorsal HC, NGF remained unaltered by either stressor alone or in combination. We propose that the restoration of NGF levels in the ventral HC may reflect a possible compensatory mechanism in response to methamphetamine exposure in adolescence following the early life stress of MS.
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Affiliation(s)
- J J Dimatelis
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory, Cape Town, South Africa, 7925,
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82
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Roque S, Mesquita AR, Palha JA, Sousa N, Correia-Neves M. The behavioral and immunological impact of maternal separation: a matter of timing. Front Behav Neurosci 2014; 8:192. [PMID: 24904343 PMCID: PMC4033212 DOI: 10.3389/fnbeh.2014.00192] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2013] [Accepted: 05/08/2014] [Indexed: 11/13/2022] Open
Abstract
Maternal separation (MS), an early life stressful event, has been demonstrated to trigger neuropsychiatric disorders later in life, in particular depression. Experiments using rodents subjected to MS protocols have been very informative for the establishment of this association. However, the mechanism by which MS leads to neuropsychiatric disorders is far from being understood. This is probably associated with the multifactorial nature of depression but also with the fact that different research MS protocols have been used (that vary on temporal windows and time of exposure to MS). In the present study, MS was induced in rats in two developmental periods: for 6 h per day for 14 days between postnatal days 2-15 (MS2-15) and 7-20 (MS7-20). These two periods were defined to differ essentially on the almost complete (MS2-15) or partial (MS7-20) overlap with the stress hypo-responsive period. Behavioral, immunological, and endocrine parameters, frequently associated with depressive-like behavior, were analyzed in adulthood. Irrespectively from the temporal window, both MS exposure periods led to increased sera corticosterone levels. However, only MS2-15 animals displayed depressive and anxious-like behaviors. Moreover, MS2-15 was also the only group presenting alterations in the immune system, displaying decreased percentage of CD8(+) T cells, increased spleen T cell CD4/CD8 ratio, and thymocytes with increased resistance to dexamethasone-induced cell death. A linear regression model performed to predict depressive-like behavior showed that both corticosterone levels and T cell CD4/CD8 ratio explained 37% of the variance observed in depressive-like behavior. Overall, these findings highlight the existence of "critical periods" for early life stressful events to exert programing effects on both central and peripheral systems, which are of relevance for distinct patterns of susceptibility to emotional disorders later in life.
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Affiliation(s)
- Susana Roque
- Life and Health Sciences Research Institute, School of Health Sciences, University of Minho , Braga , Portugal ; ICVS/3B's - PT Government Associate Laboratory , Braga , Portugal
| | - Ana Raquel Mesquita
- Life and Health Sciences Research Institute, School of Health Sciences, University of Minho , Braga , Portugal ; Neuropsychophysiology Laboratory, Center for Research in Psychology (CIPsi), School of Psychology, University of Minho , Braga , Portugal
| | - Joana A Palha
- Life and Health Sciences Research Institute, School of Health Sciences, University of Minho , Braga , Portugal ; ICVS/3B's - PT Government Associate Laboratory , Braga , Portugal
| | - Nuno Sousa
- Life and Health Sciences Research Institute, School of Health Sciences, University of Minho , Braga , Portugal ; ICVS/3B's - PT Government Associate Laboratory , Braga , Portugal
| | - Margarida Correia-Neves
- Life and Health Sciences Research Institute, School of Health Sciences, University of Minho , Braga , Portugal ; ICVS/3B's - PT Government Associate Laboratory , Braga , Portugal
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Harrison EL, Baune BT. Modulation of early stress-induced neurobiological changes: a review of behavioural and pharmacological interventions in animal models. Transl Psychiatry 2014; 4:e390. [PMID: 24825729 PMCID: PMC4035722 DOI: 10.1038/tp.2014.31] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Revised: 02/08/2014] [Accepted: 03/26/2014] [Indexed: 12/28/2022] Open
Abstract
Childhood adversity alters the predisposition to psychiatric disorders later in life. Those with psychiatric conditions and a history of early adversity exhibit a higher incidence of treatment resistance compared with individuals with no such history. Modulation of the influence early stress exerts over neurobiology may help to prevent the development of psychiatric disorders in some cases, while attenuating the extent of treatment resistance in those with established psychiatric disorders. This review aims to critically evaluate the ability of behavioural, environmental and pharmacologic interventions to modulate neurobiological changes induced by early stress in animal models. Databases were systematically searched to locate literature relevant to this review. Early adversity was defined as stress that resulted from manipulation of the mother-infant relationship. Analysis was restricted to animal models to enable characterisation of how a given intervention altered specific neurobiological changes induced by early stress. A wide variety of changes in neurobiology due to early stress are amenable to intervention. Behavioural interventions in childhood, exercise in adolescence and administration of epigenetic-modifying drugs throughout life appear to best modulate cellar and behavioural alterations induced by childhood adversity. Other pharmacotherapies, such as endocannabinoid system modulators, anti-inflammatories and antidepressants can also influence these neurobiological and behavioural changes that result from early stress, although findings are less consistent at present and require further investigation. Further work is required to examine the influence that behavioural interventions, exercise and epigenetic-modifying drugs exert over alterations that occur following childhood stress in human studies, before possible translational into clinical practice is possible.
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Affiliation(s)
- E L Harrison
- Discipline of Psychiatry, School of Medicine, University of Adelaide, Adelaide, SA, Australia,School of Medicine and Dentistry, James Cook University, Townsville, QLD, Australia
| | - B T Baune
- Discipline of Psychiatry, School of Medicine, University of Adelaide, Adelaide, SA, Australia,Discipline of Psychiatry, School of Medicine, University of Adelaide, Adelaide, SA 5005, Australia. E-mail:
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84
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Stanis JJ, Andersen SL. Reducing substance use during adolescence: a translational framework for prevention. Psychopharmacology (Berl) 2014; 231:1437-53. [PMID: 24464527 PMCID: PMC3969413 DOI: 10.1007/s00213-013-3393-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 11/30/2013] [Indexed: 11/30/2022]
Abstract
RATIONALE Most substance use is initiated during adolescence when substantial development of relevant brain circuitry is still rapidly maturing. Developmental differences in reward processing, behavioral flexibility, and self-regulation lead to changes in resilience or vulnerability to drugs of abuse depending on exposure to risk factors. Intervention and prevention approaches to reducing addiction in teens may be able to capitalize on malleable brain systems in a predictable manner. OBJECTIVE This review will highlight what is known about how factors that increase vulnerability to addiction, including developmental stage, exposure to early life adversity (ranging from abuse, neglect, and bullying), drug exposure, and genetic predisposition, impact the development of relevant systems. RESULTS AND CONCLUSIONS Appropriate, early intervention may restore the normal course of an abnormal trajectory and reduce the likelihood of developing a substance use disorder (SUD) later in life. A considerable amount is known about the functional neuroanatomy and/or pharmacology of risky behaviors based on clinical and preclinical studies, but relatively little has been directly translated to reduce their impact on addiction in high-risk children or teenagers. An opportunity exists to effectively intervene before adolescence when substance use is likely to emerge.
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Affiliation(s)
- Jessica J Stanis
- Laboratory of Developmental Neuropharmacology, McLean Hospital and Department of Psychiatry, Harvard Medical School, Mailstop 333, 115 Mill Street, Belmont, MA, 02478, USA
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85
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Kim KS, Kang YM, Kang Y, Park TS, Park HY, Kim YJ, Han BS, Kim CH, Lee CH, Ardayfio PA, Han PL, Jung BH, Kim KS. Pitx3 deficient mice as a genetic animal model of co-morbid depressive disorder and parkinsonism. Brain Res 2014; 1552:72-81. [DOI: 10.1016/j.brainres.2014.01.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 12/17/2013] [Accepted: 01/15/2014] [Indexed: 11/16/2022]
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Abstract
After participating in this educational activity, the physician should be better able to 1. Evaluate the relationship between reward processes, stress, and depression. 2. Assess the characteristics of the three etiological models of stress and reward processes. 3. Identify the biological basis for stress and reward processes. Adolescence is a peak period for the onset of depression, and it is also a time marked by substantial stress as well as neural development within the brain reward circuitry. In this review, we provide a selective overview of current animal and human research investigating the relationship among reward processes, stress, and depression. Three separate, but related, etiological models examine the differential roles that stress may play in relation to reward dysfunction and adolescent depression. First, the reward mediation model suggests that both acute and chronic stress contribute to reward deficits, which, in turn, potentiate depressive symptoms or increase the risk for depression. Second, in line with the stress generation perspective, it is plausible that premorbid reward-related dysfunction generates stress--in particular, interpersonal stress--which then leads to the manifestation of depressive symptoms. Third, consistent with a diathesis-stress model, the interaction between stress and premorbid reward dysfunction may contribute to the onset of depression. Given the equifinal nature of depression, these models could shed important light on different etiological pathways during adolescence, particularly as they may relate to understanding the heterogeneity of depression. To highlight the translational potential of these insights, a hypothetical case study is provided as a means of demonstrating the importance of targeting reward dysfunction in both assessment and treatment of adolescent depression.
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87
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Walker SC, McGlone FP. The social brain: neurobiological basis of affiliative behaviours and psychological well-being. Neuropeptides 2013; 47:379-93. [PMID: 24210942 DOI: 10.1016/j.npep.2013.10.008] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 10/14/2013] [Accepted: 10/14/2013] [Indexed: 02/07/2023]
Abstract
The social brain hypothesis proposes that the demands of the social environment provided the evolutionary pressure that led to the expansion of the primate brain. Consistent with this notion, that functioning in the social world is crucial to our survival, while close supportive relationships are known to enhance well-being, a range of social stressors such as abuse, discrimination and dysfunctional relationships can increase the risk of psychiatric disorders. The centrality of the social world to our everyday lives is further exemplified by the fact that abnormality in social behaviour is a salient feature of a range of neurodevelopmental and psychiatric disorders. This paper aims to provide a selective overview of current knowledge of the neurobiological basis of our ability to form and maintain close personal relationships, and of the benefits these relationships confer on our health. Focusing on neurochemical and neuroendocrine interactions within affective and motivational neural circuits, it highlights the specific importance of cutaneous somatosensation in affiliative behaviours and psychological well-being and reviews evidence, in support of the hypothesis, that a class of cutaneous unmyelinated, low threshold mechanosensitive nerves, named c-tactile afferents, have a direct and specific role in processing affiliative tactile stimuli.
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Affiliation(s)
- S C Walker
- School of Natural Sciences & Psychology, Liverpool John Moores University, Tom Reilly Building, Byrom Street, Liverpool L3 3AF, United Kingdom.
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88
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Arenas A, Ramírez GP, Balbuena MS, Farina WM. Behavioral and neural plasticity caused by early social experiences: the case of the honeybee. Front Physiol 2013; 4:41. [PMID: 23986708 PMCID: PMC3750948 DOI: 10.3389/fphys.2013.00041] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 02/17/2013] [Indexed: 11/29/2022] Open
Abstract
Cognitive experiences during the early stages of life play an important role in shaping future behavior. Behavioral and neural long-term changes after early sensory and associative experiences have been recently reported in the honeybee. This invertebrate is an excellent model for assessing the role of precocious experiences on later behavior due to its extraordinarily tuned division of labor based on age polyethism. These studies are mainly focused on the role and importance of experiences occurred during the first days of the adult lifespan, their impact on foraging decisions, and their contribution to coordinate food gathering. Odor-rewarded experiences during the first days of honeybee adulthood alter the responsiveness to sucrose, making young hive bees more sensitive to assess gustatory features about the nectar brought back to the hive and affecting the dynamic of the food transfers and the propagation of food-related information within the colony. Early olfactory experiences lead to stable and long-term associative memories that can be successfully recalled after many days, even at foraging ages. Also they improve memorizing of new associative learning events later in life. The establishment of early memories promotes stable reorganization of the olfactory circuits inducing structural and functional changes in the antennal lobe (AL). Early rewarded experiences have relevant consequences at the social level too, biasing dance and trophallaxis partner choice and affecting recruitment. Here, we revised recent results in bees' physiology, behavior, and sociobiology to depict how the early experiences affect their cognition abilities and neural-related circuits.
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Affiliation(s)
| | | | | | - Walter M. Farina
- Grupo de Estudio de Insectos Sociales, Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, IFIBYNE-CONICET, Universidad de Buenos AiresBuenos Aires, Argentina
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89
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Persistent effects of prior chronic exposure to corticosterone on reward-related learning and motivation in rodents. Psychopharmacology (Berl) 2013; 225:569-77. [PMID: 22983097 PMCID: PMC3546199 DOI: 10.1007/s00213-012-2844-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Accepted: 08/06/2012] [Indexed: 10/27/2022]
Abstract
BACKGROUND Repeated or prolonged exposure to stress has profound effects on a wide spectrum of behavioral and neurobiological processes and has been associated with the pathophysiology of depression. The multifaceted nature of this disorder includes despair, anhedonia, diminished motivation, and disrupted cognition, and it has been proposed that depression is also associated with reduced reward-motivated learning. We have previously reported that prior chronic corticosterone exposure to mice produces a lasting depressive-like state that can be reversed by chronic antidepressant treatment. METHODS In the present study, we tested the effects of prior chronic exposure to corticosterone (50 μg/ml) administered to rats or to mice in drinking water for 14 days followed by dose-tapering over 9 days. RESULTS The exposure to corticosterone produced lasting deficits in the acquisition of reward-related learning tested on a food-motivated instrumental task conducted 10-20 days after the last day of full dose corticosterone exposure. Rats exposed to corticosterone also displayed reduced responding on a progressive ratio schedule of reinforcement when tested on day 21 after exposure. Amitriptyline (200 mg/ml in drinking water) exposure for 14 days to mice produced the opposite effect, enhancing food-motivated instrumental acquisition and performance. Repeated treatment with amitriptyline (5 mg/kg, intraperitoneally; bid) subsequent to corticosterone exposure also prevented the corticosterone-induced deficits in rats. CONCLUSIONS These results are consistent with aberrant reward-related learning and motivational processes in depressive states and provide new evidence that stress-induced neuroadaptive alterations in cortico-limbic-striatal brain circuits involved in learning and motivation may play a critical role in aspects of mood disorders.
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90
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Bardo MT, Neisewander JL, Kelly TH. Individual differences and social influences on the neurobehavioral pharmacology of abused drugs. Pharmacol Rev 2013; 65:255-90. [PMID: 23343975 PMCID: PMC3565917 DOI: 10.1124/pr.111.005124] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The interaction of drugs with biologic targets is a critical area of research, particularly for the development of medications to treat substance use disorders. In addition to understanding these drug-target interactions, however, there is a need to understand more fully the psychosocial influences that moderate these interactions. The first section of this review introduces some examples from human behavioral pharmacology that illustrate the clinical importance of this research. The second section covers preclinical evidence to characterize some of the key individual differences that alter drug sensitivity and abuse vulnerability, related primarily to differences in response to novelty and impulsivity. Evidence is presented to indicate that critical neuropharmacological mechanisms associated with these individual differences involve integrated neurocircuits underlying stress, reward, and behavioral inhibitory processes. The third section covers social influences on drug abuse vulnerability, including effects experienced during infancy, adolescence, and young adulthood, such as maternal separation, housing conditions, and social interactions (defeat, play, and social rank). Some of the same neurocircuits involved in individual differences also are altered by social influences, although the precise neurochemical and cellular mechanisms involved remain to be elucidated fully. Finally, some speculation is offered about the implications of this research for the prevention and treatment of substance abuse.
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Affiliation(s)
- M T Bardo
- Department of Psychology, University of Kentucky, BBSRB Room 447, 741 S. Limestone, Lexington, KY 40536-0509, USA.
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91
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Réus GZ, Dos Santos MAB, Abelaira HM, Ribeiro KF, Petronilho F, Vuolo F, Colpo GD, Pfaffenseller B, Kapczinski F, Dal-Pizzol F, Quevedo J. Imipramine reverses alterations in cytokines and BDNF levels induced by maternal deprivation in adult rats. Behav Brain Res 2012; 242:40-6. [PMID: 23238043 DOI: 10.1016/j.bbr.2012.11.044] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 11/26/2012] [Accepted: 11/30/2012] [Indexed: 01/19/2023]
Abstract
A growing body of evidence is pointing toward an association between immune molecules, as well brain-derived neurotrophic factor (BDNF) and the depression. The present study was aimed to evaluate the behavioral and molecular effects of the antidepressant imipramine in maternally deprived adult rats. To this aim, maternally deprived and non-deprived (control group) male rats were treated with imipramine (30mg/kg) once a day for 14 days during their adult phase. Their behavior was then assessed using the forced swimming test. In addition to this, IL-10, TNF-α and IL-1β cytokines were assessed in the serum and cerebrospinal fluid (CSF). In addition, BDNF protein levels were assessed in the prefrontal cortex, hippocampus and amygdala. In deprived rats treated with saline was observed an increase on immobility time, compared with non-deprived rats treated with imipramine (p<0.05). Deprived rats treated with saline presented a decrease on BDNF levels in the amygdala (p<0.05), compared with all other groups. The IL-10 levels were decreased in the serum (p<0.05). TNF-α and IL-1β levels were increased in the serum and CSF of deprived rats treated with saline (p<0.05). Interestingly, imipramine treatment reversed the effects of maternal deprivation on BDNF and cytokines levels (p<0.05). Finally, these findings further support a relationship between immune activation, neurotrophins and the depression, and considering the action of imipramine, it is suggested that classic antidepressants could exert their effects by modulating the immune system.
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Affiliation(s)
- Gislaine Z Réus
- Laboratório de Neurociências, Instituto Nacional de Ciência e Tecnologia Translacional em Medicina (INCT-TM), and Núcleo de Excelência em Neurociências Aplicadas de Santa Catarina (NENASC), Programa de Pós-Graduação em Ciências da Saúde, Unidade Acadêmica de Ciências da Saúde, Universidade do Extremo Sul Catarinense, 88806-000 Criciúma, SC, Brazil.
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92
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Hall FS, Perona MTG. Have studies of the developmental regulation of behavioral phenotypes revealed the mechanisms of gene-environment interactions? Physiol Behav 2012; 107:623-40. [PMID: 22643448 PMCID: PMC3447116 DOI: 10.1016/j.physbeh.2012.05.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 05/15/2012] [Accepted: 05/15/2012] [Indexed: 12/30/2022]
Abstract
This review addresses the recent convergence of our long-standing knowledge of the regulation of behavioral phenotypes by developmental experience with recent advances in our understanding of mechanisms regulating gene expression. This review supports a particular perspective on the developmental regulation of behavioral phenotypes: That the role of common developmental experiences (e.g. maternal interactions, peer interactions, exposure to a complex environment, etc.) is to fit individuals to the circumstances of their lives within bounds determined by long-standing (evolutionary) mechanisms that have shaped responses to critical and fundamental types of experience via those aspects of gene structure that regulate gene expression. The phenotype of a given species is not absolute for a given genotype but rather variable within bounds that is determined by mechanisms regulated by experience (e.g. epigenetic mechanisms). This phenotypic variation is not necessarily random, or evenly distributed along a continuum of description or measurement, but often highly disjointed, producing distinct, even opposing, phenotypes. The potentiality for these varying phenotypes is itself the product of evolution, the potential for alternative phenotypes itself conveying evolutionary advantage. Examples of such phenotypic variation, resulting from environmental or experiential influences, have a long history of study in neurobiology, and a number of these will be discussed in this review: neurodevelopmental experiences that produce phenotypic variation in visual perception, cognitive function, and emotional behavior. Although other examples will be discussed, particular emphasis will be made on the role of social behavior on neurodevelopment and phenotypic determination. It will be argued that an important purpose of some aspects of social behavior is regulation of neurobehavioral phenotypes by experience via genetic regulatory mechanisms.
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Affiliation(s)
- F Scott Hall
- Molecular Neurobiology Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, 333 Cassel Drive, Baltimore, MD 21224, United States.
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93
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Neisewander J, Peartree N, Pentkowski N. Emotional valence and context of social influences on drug abuse-related behavior in animal models of social stress and prosocial interaction. Psychopharmacology (Berl) 2012; 224:33-56. [PMID: 22955569 PMCID: PMC4071609 DOI: 10.1007/s00213-012-2853-3] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Accepted: 08/18/2012] [Indexed: 02/07/2023]
Abstract
RATIONALE Social factors are important determinants of drug dependence and relapse. OBJECTIVES We reviewed pre-clinical literature examining the role of social experiences from early life through the development of drug dependence and relapse, emphasizing two aspects of these experiences: (1) whether the social interaction is appetitive or aversive and (2) whether the social interaction occurs within or outside of the drug-taking context. METHODS The models reviewed include neonatal care, isolation, social defeat, chronic subordination, and prosocial interactions. We review results from these models in regard to effects on self-administration and conditioned place preference established with alcohol, psychostimulants, and opiates. RESULTS We suggest that in general, when the interactions occur outside of the drug-taking context, prosocial interactions are protective against drug abuse-related behaviors, whereas social stressors facilitate these behaviors. By contrast, positive or negative social interactions occurring within the drug-taking context may interact with other risk factors to enhance or inhibit these behaviors. CONCLUSIONS Despite differences in the nature and complexity of human social behavior compared to other species, the evolving animal literature provides useful models for understanding social influences on drug abuse-related behavior that will allow for research on the behavioral and biological mechanisms involved. The models have contributed to understanding social influences on initiation and maintenance of drug use, but more research is needed to understand social influences on drug relapse.
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Affiliation(s)
- J.L. Neisewander
- School of Life Sciences, Arizona State University, PO Box 874501, Tempe, AZ 85287-4501,Corresponding author: Janet Neisewander, Ph.D., School of Life Sciences, Arizona State University, PO Box 874501, Tempe, AZ 85287-4501, , Phone: 480-965-0209, Fax: 480-965-6899
| | - N.A. Peartree
- Department of Psychology, Arizona State University, PO Box 871104, Tempe, AZ 85287-1104
| | - N.S. Pentkowski
- School of Life Sciences, Arizona State University, PO Box 874501, Tempe, AZ 85287-4501
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Dimatelis JJ, Russell VA, Stein DJ, Daniels WM. Effects of maternal separation and methamphetamine exposure on protein expression in the nucleus accumbens shell and core. Metab Brain Dis 2012; 27:363-75. [PMID: 22451087 DOI: 10.1007/s11011-012-9295-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 03/15/2012] [Indexed: 12/14/2022]
Abstract
Early life adversity has been suggested to predispose an individual to later drug abuse. The core and shell sub-regions of the nucleus accumbens are differentially affected by both stressors and methamphetamine. This study aimed to characterize and quantify methamphetamine-induced protein expression in the shell and core of the nucleus accumbens in animals exposed to maternal separation during early development. Isobaric tagging (iTRAQ) which enables simultaneous identification and quantification of peptides with tandem mass spectrometry (MS/MS) was used. We found that maternal separation altered more proteins involved in structure and redox regulation in the shell than in the core of the nucleus accumbens, and that maternal separation and methamphetamine had differential effects on signaling proteins in the shell and core. Compared to maternal separation or methamphetamine alone, the maternal separation/methamphetamine combination altered more proteins involved in energy metabolism, redox regulatory processes and neurotrophic proteins. Methamphetamine treatment of rats subjected to maternal separation caused a reduction of cytoskeletal proteins in the shell and altered cytoskeletal, signaling, energy metabolism and redox proteins in the core. Comparison of maternal separation/methamphetamine to methamphetamine alone resulted in decreased cytoskeletal proteins in both the shell and core and increased neurotrophic proteins in the core. This study confirms that both early life stress and methamphetamine differentially affect the shell and core of the nucleus accumbens and demonstrates that the combination of early life adversity and later methamphetamine use results in more proteins being affected in the nucleus accumbens than either treatment alone.
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Affiliation(s)
- J J Dimatelis
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Observatory, 7925 Cape Town, South Africa.
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Dimatelis JJ, Russell VA, Stein DJ, Daniels WM. The effects of lobeline and naltrexone on methamphetamine-induced place preference and striatal dopamine and serotonin levels in adolescent rats with a history of maternal separation. Metab Brain Dis 2012; 27:351-61. [PMID: 22392627 DOI: 10.1007/s11011-012-9288-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 02/14/2012] [Indexed: 01/01/2023]
Abstract
Exposure to early life stress has been suggested to increase an individual's vulnerability to methamphetamine (MA) dependence. Although there is no cure for drug dependence, the opioid and vesicular monoamine transporter 2 (VMAT2) systems may be useful targets for treatment insofar as they play pivotal roles in the neurochemistry of addiction. Here we investigated the effects of naltrexone (opioid antagonist) and lobeline (VMAT2 inhibitor) on MA-induced place preference in adolescent rodents subjected to early life trauma (maternal separation, MS) and controls, as well as the effects on dopamine and serotonin levels in the striatum. We found: (1) maternal separation attenuated methamphetamine-induced place preference; (2) lobeline and naltrexone treatment had differential effects on serotonin and dopamine concentrations in the striatum, naltrexone increased serotonin levels in the maternally separated animals. The hypothesized effect of early adversity increasing MA-induced place preference may not be apparent in adolescence. However the data are consistent with the hypothesis that early life stress influences neurochemical pathways that predispose an individual to drug dependence.
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Affiliation(s)
- J J Dimatelis
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Observatory 7925, Cape Town, South Africa.
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96
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Ventura R, Coccurello R, Andolina D, Latagliata EC, Zanettini C, Lampis V, Battaglia M, D'Amato FR, Moles A. Postnatal aversive experience impairs sensitivity to natural rewards and increases susceptibility to negative events in adult life. ACTA ACUST UNITED AC 2012; 23:1606-17. [PMID: 22669969 DOI: 10.1093/cercor/bhs145] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Evidence shows that maternal care and postnatal traumatic events can exert powerful effects on brain circuitry development but little is known about the impact of early postnatal experiences on processing of rewarding and aversive stimuli related to the medial prefrontal cortex (mpFC) function in adult life. In this study, the unstable maternal environment induced by repeated cross-fostering (RCF) impaired palatable food conditioned place preference and disrupted the natural preference for sweetened fluids in the saccharin preference test. By contrast, RCF increased sensitivity to conditioned place aversion (CPA) and enhanced immobility in the forced swimming test. Intracerebral microdialysis data showed that the RCF prevents mpFC dopamine (DA) outflow regardless of exposure to rewarding or aversive stimuli, whereas it induces a strong and sustained prefrontal norepinephrine (NE) release in response to different aversive experiences. Moreover, the selective mpFC NE depletion abolished CPA, thus indicating that prefrontal NE is required for motivational salience attribution to aversion-related stimuli. These findings demonstrate that an unstable maternal environment impairs the natural propensity to seek pleasurable sources of reward, enhances sensitivity to negative events in adult life, blunts prefrontal DA outflow, and modulates NE release in the reverse manner depending on the exposure to rewarding or aversive stimuli.
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Affiliation(s)
- Rossella Ventura
- Santa Lucia Foundation, European Centre for Brain Research (CERC), Roma, Italy.
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Martinowich K, Cardinale KM, Schloesser RJ, Hsu M, Greig NH, Manji HK. Acetylcholinesterase inhibition ameliorates deficits in motivational drive. Behav Brain Funct 2012; 8:15. [PMID: 22433906 PMCID: PMC3328273 DOI: 10.1186/1744-9081-8-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Accepted: 03/20/2012] [Indexed: 12/05/2022] Open
Abstract
Background Apathy is frequently observed in numerous neurological disorders, including Alzheimer's and Parkinson's, as well as neuropsychiatric disorders including schizophrenia. Apathy is defined as a lack of motivation characterized by diminished goal-oriented behavior and self-initiated activity. This study evaluated a chronic restraint stress (CRS) protocol in modeling apathetic behavior, and determined whether administration of an anticholinesterase had utility in attenuating CRS-induced phenotypes. Methods We assessed behavior as well as regional neuronal activity patterns using FosB immunohistochemistry after exposure to CRS for 6 h/d for a minimum of 21 d. Based on our FosB findings and recent clinical trials, we administered an anticholinesterase to evaluate attenuation of CRS-induced phenotypes. Results CRS resulted in behaviors that reflect motivational loss and diminished emotional responsiveness. CRS-exposed mice showed differences in FosB accumulation, including changes in the cholinergic basal forebrain system. Facilitating cholinergic signaling ameliorated CRS-induced deficits in initiation and motivational drive and rescued immediate early gene activation in the medial septum and nucleus accumbens. Conclusions Some CRS protocols may be useful for studying deficits in motivation and apathetic behavior. Amelioration of CRS-induced behaviors with an anticholinesterase supports a role for the cholinergic system in remediation of deficits in motivational drive.
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Affiliation(s)
- Keri Martinowich
- Mood and Anxiety Disorders Program, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892-3711, USA.
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98
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Tejeda HA, Shippenberg TS, Henriksson R. The dynorphin/κ-opioid receptor system and its role in psychiatric disorders. Cell Mol Life Sci 2012; 69:857-96. [PMID: 22002579 PMCID: PMC11114766 DOI: 10.1007/s00018-011-0844-x] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 09/16/2011] [Accepted: 09/19/2011] [Indexed: 10/16/2022]
Abstract
The dynorphin/κ-opioid receptor system has been implicated in the pathogenesis and pathophysiology of several psychiatric disorders. In the present review, we present evidence indicating a key role for this system in modulating neurotransmission in brain circuits that subserve mood, motivation, and cognitive function. We overview the pharmacology, signaling, post-translational, post-transcriptional, transcriptional, epigenetic and cis regulation of the dynorphin/κ-opioid receptor system, and critically review functional neuroanatomical, neurochemical, and pharmacological evidence, suggesting that alterations in this system may contribute to affective disorders, drug addiction, and schizophrenia. We also overview the dynorphin/κ-opioid receptor system in the genetics of psychiatric disorders and discuss implications of the reviewed material for therapeutics development.
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Affiliation(s)
- H. A. Tejeda
- Integrative Neuroscience Section, Integrative Neuroscience Research Branch, NIDA-IRP, NIH, 333 Cassell Dr., Baltimore, MD 21224 USA
- Department of Anatomy and Neurobiology, University of Maryland, Baltimore, 20 Penn St., Baltimore, MD 21201 USA
| | - T. S. Shippenberg
- Integrative Neuroscience Section, Integrative Neuroscience Research Branch, NIDA-IRP, NIH, 333 Cassell Dr., Baltimore, MD 21224 USA
| | - R. Henriksson
- Integrative Neuroscience Section, Integrative Neuroscience Research Branch, NIDA-IRP, NIH, 333 Cassell Dr., Baltimore, MD 21224 USA
- Department of Clinical Neuroscience, Karolinska Institutet, CMM, L8:04, 17176 Stockholm, Sweden
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99
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Lomanowska AM, Chatterjee-Chakraborty M, Steiner M, Kraemer GW. Effects of motherless rearing on basal and stress-induced corticosterone secretion in rat pups. Stress 2011; 14:685-96. [PMID: 21790476 DOI: 10.3109/10253890.2011.594470] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Rearing of rat pups without a mother, artificial rearing (AR), produces substantial changes in the pups' behavior in later life. These changes are similar to those produced by the stress of repeated mother-pup separations. The predominant interpretation is that the long-term effects of disruptions to the mother-pup relationship are mediated by exposure to elevated levels of corticosterone which affect the development of neurobiological systems underlying cognition and behavior. Indeed, repeated separation of pups from the mother sensitizes the pups' corticosterone response to stress. This study examined basal and stress-induced corticosterone release in AR pups. Corticosterone levels were increased immediately following implantation of feeding cannulae. One day after the start of AR, circulating concentrations of corticosterone were not increased unless AR pups were challenged with an additional stressor (injection). Corticosterone levels were lowest when cannulation and AR started on postnatal day (PND) 5 compared with earlier PNDs. On PND 12, there was no evidence of increased corticosterone levels in AR pups at baseline or in response to stress, indicating that AR did not result in persistent sensitization of corticosterone release. The long-term effects of motherless rearing on rat behavior are mediated by mechanisms that are independent of sustained early corticosterone exposure.
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Affiliation(s)
- A M Lomanowska
- Department of Psychology, University of Toronto at Mississauga, Ontario, Canada
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100
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Afonso VM, King SJ, Novakov M, Burton CL, Fleming AS. Accumbal dopamine function in postpartum rats that were raised without their mothers. Horm Behav 2011; 60:632-43. [PMID: 21964046 DOI: 10.1016/j.yhbeh.2011.08.016] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 08/20/2011] [Accepted: 08/24/2011] [Indexed: 11/21/2022]
Abstract
Postpartum rats that had been previously raised in an artificial rearing (AR) apparatus, without their mothers or siblings during the preweaning period, show altered maternal responses towards their own offspring in adulthood. In mother-reared (MR) rats, nucleus accumbens (NAC) dopamine (DA) responses to pups evoke a robust sustained rise during the postpartum period and following treatment with estrogen/progesterone parturient-like hormones (Afonso et al., 2009). These MR females had siblings that received AR rearing with varying amounts of preweaning tactile stimulation (ARmin; ARmax). The present study examined NACshell DA responses to pup and food stimuli in these AR rats, and statistically compared them to their MR siblings. Microdialysis samples were collected from adult (90 days postnatal) AR females in different parity states (cycling vs. postpartum, Exp. 1), or after ovariectomy with different hormone treatments (sham vs. hormone, Exp. 2. After basal sample collection, pup and then food stimuli were individually presented to the females in the dialysis chamber. As with their MR siblings, basal DA concentrations were lower and pup-evoked DA responses greater in hormonally-primed AR females than in non-primed AR controls. Compared to their postpartum MR sisters (Exp. 1), AR rats had increased basal DA levels, reduced pup related DA elevations, and disrupted maternal behavior. The postpartum AR impairment in pup-evoked DA was reversed by additional pre-weaning tactile stimulation. Exogenous hormones (Exp. 2) eliminated AR impairments on pup-evoked DA responses. Although MR and AR siblings had comparable DA responses to food stimuli, upon reanalyzing MR data it was found that only postpartum dams had DA responses to pups greater than to food. These data suggest that that the hormonally induced suppression of basal DA levels may reflect saliency of pups which was greater in MR than in AR dams. Preweaning tactile stimulation could partially reverse these effects only in naturally cycling or parturient animals.
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Affiliation(s)
- Veronica M Afonso
- Department of Psychology, University of Toronto at Mississauga, 3359 Mississauga Rd N, Mississauga, ON, Canada L5L 1C6.
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