1
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Liu SX, Harris AC, Gewirtz JC. How life events may confer vulnerability to addiction: the role of epigenetics. Front Mol Neurosci 2024; 17:1462769. [PMID: 39359689 PMCID: PMC11446245 DOI: 10.3389/fnmol.2024.1462769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2024] [Accepted: 09/02/2024] [Indexed: 10/04/2024] Open
Abstract
Substance use disorder (SUD) represents a large and growing global health problem. Despite the strong addictive potency of drugs of abuse, only a minority of those exposed develop SUDs. While certain life experiences (e.g., childhood trauma) may increase subsequent vulnerability to SUDs, mechanisms underlying these effects are not yet well understood. Given the chronic and relapsing nature of SUDs, and the length of time that can elapse between prior life events and subsequent drug exposure, changes in SUD vulnerability almost certainly involve long-term epigenetic dysregulation. To validate this idea, functional effects of specific epigenetic modifications in brain regions mediating reinforcement learning (e.g., nucleus accumbens, prefrontal cortex) have been investigated in a variety of animal models of SUDs. In addition, the effects of epigenetic modifications produced by prior life experiences on subsequent SUD vulnerability have been studied, but mostly in a correlational manner. Here, we review how epigenetic mechanisms impact SUD-related behavior in animal models and summarize our understanding of the relationships among life experiences, epigenetic regulation, and future vulnerability to SUDs. Despite variations in study design, epigenetic modifications that most consistently affect SUD-related behavior are those that produce predominantly unidirectional effects on gene regulation, such as DNA methylation and histone phosphorylation. Evidence explicitly linking environmentally induced epigenetic modifications to subsequent SUD-related behavior is surprisingly sparse. We conclude by offering several directions for future research to begin to address this critical research gap.
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Affiliation(s)
- Shirelle X Liu
- Department of Psychology, University of Minnesota, Minneapolis, MN, United States
| | - Andrew C Harris
- Department of Psychology, University of Minnesota, Minneapolis, MN, United States
- Department of Medicine, University of Minnesota, Minneapolis, MN, United States
- Hennepin Healthcare Research Institute, Minneapolis, MN, United States
| | - Jonathan C Gewirtz
- Department of Psychology, University of Minnesota, Minneapolis, MN, United States
- Department of Psychology, Arizona State University, Tempe, AZ, United States
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2
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Rusch JA, Layden BT, Dugas LR. Signalling cognition: the gut microbiota and hypothalamic-pituitary-adrenal axis. Front Endocrinol (Lausanne) 2023; 14:1130689. [PMID: 37404311 PMCID: PMC10316519 DOI: 10.3389/fendo.2023.1130689] [Citation(s) in RCA: 27] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 05/25/2023] [Indexed: 07/06/2023] Open
Abstract
Cognitive function in humans depends on the complex and interplay between multiple body systems, including the hypothalamic-pituitary-adrenal (HPA) axis. The gut microbiota, which vastly outnumbers human cells and has a genetic potential that exceeds that of the human genome, plays a crucial role in this interplay. The microbiota-gut-brain (MGB) axis is a bidirectional signalling pathway that operates through neural, endocrine, immune, and metabolic pathways. One of the major neuroendocrine systems responding to stress is the HPA axis which produces glucocorticoids such as cortisol in humans and corticosterone in rodents. Appropriate concentrations of cortisol are essential for normal neurodevelopment and function, as well as cognitive processes such as learning and memory, and studies have shown that microbes modulate the HPA axis throughout life. Stress can significantly impact the MGB axis via the HPA axis and other pathways. Animal research has advanced our understanding of these mechanisms and pathways, leading to a paradigm shift in conceptual thinking about the influence of the microbiota on human health and disease. Preclinical and human trials are currently underway to determine how these animal models translate to humans. In this review article, we summarize the current knowledge of the relationship between the gut microbiota, HPA axis, and cognition, and provide an overview of the main findings and conclusions in this broad field.
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Affiliation(s)
- Jody A. Rusch
- Division of Chemical Pathology, Department of Pathology, University of Cape Town, Cape Town, South Africa
- C17 Chemical Pathology Laboratory, Groote Schuur Hospital, National Health Laboratory Service, Cape Town, South Africa
| | - Brian T. Layden
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Illinois at Chicago, Chicago, IL, United States
- Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, IL, United States
| | - Lara R. Dugas
- Division of Epidemiology and Biostatistics, School of Public Health, University of Cape Town, Cape Town, South Africa
- Public Health Sciences, Parkinson School of Health Sciences and Public Health, Loyola University Chicago, Maywood, IL, United States
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3
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Effects of early life adversities upon memory processes and cognition in rodent models. Neuroscience 2022; 497:282-307. [PMID: 35525496 DOI: 10.1016/j.neuroscience.2022.04.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 04/24/2022] [Accepted: 04/27/2022] [Indexed: 01/14/2023]
Abstract
Exposure to stressors in early postnatal life induces long-lasting modifications in brainfunction.Thisplasticity,an essential characteristic of the brain that enables adaptation to the environment, may also induce impairments in some psychophysiological functions, including learning and memory. Early life stress (ELS) has long-term effects on thehypothalamic-pituitary-adrenal axisresponse to stressors, and has been reported to lead toneuroinflammation,altered levelsof neurotrophic factors, modifications inneurogenesis andsynaptic plasticity,with changes in neurotransmitter systems and network functioning. In this review, we focus on early postnatal stress in animal models and their effects on learning and memory.Many studies have reported ELS-induced impairments in different types of memories, including spatial memory, fear memory, recognition (both for objects and social) memory, working memory and reversal learning. Studies are not always in agreement, however, no effects, or sometimes facilitation, being reported, depending on the nature and intensity of the early intervention, as well as the age when the outcome was evaluated and the sex of the animals. When considering processes occurring after consolidation, related with memory maintenance or modification, there are a very reduced number of reports. Future studies addressing the mechanisms underlying memory changes for ELS should shed some light on the understanding of the different effects induced by stressors of different types and intensities on cognitive functions.
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4
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Juvenile handling rescues autism-related effects of prenatal exposure to valproic acid. Sci Rep 2022; 12:7174. [PMID: 35504947 PMCID: PMC9065111 DOI: 10.1038/s41598-022-11269-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 04/13/2022] [Indexed: 11/12/2022] Open
Abstract
Environmental factors acting on young animals affect neurodevelopmental trajectories and impact adult brain function and behavior. Psychiatric disorders may be caused or worsen by environmental factors, but early interventions can improve performance. Understanding the possible mechanisms acting upon the developing brain could help identify etiological factors of psychiatric disorders and enable advancement of effective therapies. Research has focused on the long-lasting effects of environmental factors acting during the perinatal period, therefore little is known about the impact of these factors at later ages when neurodevelopmental pathologies such as autism spectrum disorder (ASD) are usually diagnosed. Here we show that handling mice during the juvenile period can rescue a range of behavioral and cellular effects of prenatal valproic acid (VPA) exposure. VPA-exposed animals show reduced sociability and increased repetitive behaviors, along with other autism-related endophenotypes such as increased immobility in the forced swim test and increased neuronal activity in the piriform cortex (Pir). Our results demonstrate that briefly handling mice every other day between postnatal days 22 and 34 can largely rescue these phenotypes. This effect can also be observed when animals are analyzed across tests using an “autism” factor, which also discriminates between animals with high and low Pir neuron activity. Thus, we identified a juvenile developmental window when environmental factors can determine adult autism-related behavior. In addition, our results have broader implications on behavioral neuroscience, as they highlight the importance of adequate experimental design and control of behavioral experiments involving treating or testing young animals.
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5
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Reddaway J, Brydges NM. Enduring neuroimmunological consequences of developmental experiences: From vulnerability to resilience. Mol Cell Neurosci 2020; 109:103567. [PMID: 33068720 PMCID: PMC7556274 DOI: 10.1016/j.mcn.2020.103567] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 09/14/2020] [Accepted: 10/12/2020] [Indexed: 12/14/2022] Open
Abstract
The immune system is crucial for normal neuronal development and function (neuroimmune system). Both immune and neuronal systems undergo significant postnatal development and are sensitive to developmental programming by environmental experiences. Negative experiences from infection to psychological stress at a range of different time points (in utero to adolescence) can permanently alter the function of the neuroimmune system: given its prominent role in normal brain development and function this dysregulation may increase vulnerability to psychiatric illness. In contrast, positive experiences such as exercise and environmental enrichment are protective and can promote resilience, even restoring the detrimental effects of negative experiences on the neuroimmune system. This suggests the neuroimmune system is a viable therapeutic target for treatment and prevention of psychiatric illnesses, especially those related to stress. In this review we will summarise the main cells, molecules and functions of the immune system in general and with specific reference to central nervous system development and function. We will then discuss the effects of negative and positive environmental experiences, especially during development, in programming the long-term functioning of the neuroimmune system. Finally, we will review the sparse but growing literature on sex differences in neuroimmune development and response to environmental experiences. The immune system is essential for development and function of the central nervous system (neuroimmune system) Environmental experiences can permanently alter neuroimmune function and associated brain development Altered neuroimmune function following negative developmental experiences may play a role in psychiatric illnesses Positive experiences can promote resilience and rescue the effects of negative experiences on the neuroimmune system The neuroimmune system is therefore a viable therapeutic target for preventing and treating psychiatric illnesses
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Affiliation(s)
- Jack Reddaway
- Neuroscience and Mental Health Research Institute, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff CF24 4HQ, UK
| | - Nichola M Brydges
- Neuroscience and Mental Health Research Institute, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff CF24 4HQ, UK.
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6
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Nordgreen J, Edwards SA, Boyle LA, Bolhuis JE, Veit C, Sayyari A, Marin DE, Dimitrov I, Janczak AM, Valros A. A Proposed Role for Pro-Inflammatory Cytokines in Damaging Behavior in Pigs. Front Vet Sci 2020; 7:646. [PMID: 33134341 PMCID: PMC7562715 DOI: 10.3389/fvets.2020.00646] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 08/10/2020] [Indexed: 12/28/2022] Open
Abstract
Sickness can change our mood for the worse, leaving us sad, lethargic, grumpy and less socially inclined. This mood change is part of a set of behavioral symptoms called sickness behavior and has features in common with core symptoms of depression. Therefore, the physiological changes induced by immune activation, for example following infection, are in the spotlight for explaining mechanisms behind mental health challenges such as depression. While humans may take a day off and isolate themselves until they feel better, farm animals housed in groups have only limited possibilities for social withdrawal. We suggest that immune activation could be a major factor influencing social interactions in pigs, with outbreaks of damaging behavior such as tail biting as a possible result. The hypothesis presented here is that the effects of several known risk factors for tail biting are mediated by pro-inflammatory cytokines, proteins produced by the immune system, and their effect on neurotransmitter systems. We describe the background for and implications of this hypothesis.
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Affiliation(s)
- Janicke Nordgreen
- Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Sandra A. Edwards
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Laura Ann Boyle
- Teagasc Animal and Grassland Research and Innovation Centre, Fermoy, Ireland
| | - J. Elizabeth Bolhuis
- Adaptation Physiology Group, Wageningen University & Research, Wageningen, Netherlands
| | - Christina Veit
- Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Amin Sayyari
- Department of Production Animal Clinical Science, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Daniela E. Marin
- National Institute for Research and Development for Biology and Animal Nutrition, Balotesti, Romania
| | | | - Andrew M. Janczak
- Department of Production Animal Clinical Science, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Anna Valros
- Department of Production Animal Medicine, Research Centre for Animal Welfare, University of Helsinki, Helsinki, Finland
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7
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Microglial Function in the Effects of Early-Life Stress on Brain and Behavioral Development. J Clin Med 2020; 9:jcm9020468. [PMID: 32046333 PMCID: PMC7074320 DOI: 10.3390/jcm9020468] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 01/30/2020] [Accepted: 02/05/2020] [Indexed: 02/06/2023] Open
Abstract
The putative effects of early-life stress (ELS) on later behavior and neurobiology have been widely investigated. Recently, microglia have been implicated in mediating some of the effects of ELS on behavior. In this review, findings from preclinical and clinical literature with a specific focus on microglial alterations induced by the exposure to ELS (i.e., exposure to behavioral stressors or environmental agents and infection) are summarized. These studies were utilized to interpret changes in developmental trajectories based on the time at which the stress occurred, as well as the paradigm used. ELS and microglial alterations were found to be associated with a wide array of deficits including cognitive performance, memory, reward processing, and processing of social stimuli. Four general conclusions emerged: (1) ELS interferes with microglial developmental programs, including their proliferation and death and their phagocytic activity; (2) this can affect neuronal and non-neuronal developmental processes, which are dynamic during development and for which microglial activity is instrumental; (3) the effects are extremely dependent on the time point at which the investigation is carried out; and (4) both pre- and postnatal ELS can prime microglial reactivity, indicating a long-lasting alteration, which has been implicated in behavioral abnormalities later in life.
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8
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Brydges NM, Reddaway J. Neuroimmunological effects of early life experiences. Brain Neurosci Adv 2020; 4:2398212820953706. [PMID: 33015371 PMCID: PMC7513403 DOI: 10.1177/2398212820953706] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 08/07/2020] [Indexed: 12/18/2022] Open
Abstract
Exposure to adverse experiences during development increases the risk of psychiatric illness later in life. Growing evidence suggests a role for the neuroimmune system in this relationship. There is now substantial evidence that the immune system is critical for normal brain development and behaviour, and responds to environmental perturbations experienced early in life. Severe or chronic stress results in dysregulated neuroimmune function, concomitant with abnormal brain morphology and function. Positive experiences including environmental enrichment and exercise exert the opposite effect, promoting normal brain and immune function even in the face of early life stress. The neuroimmune system may therefore provide a viable target for prevention and treatment of psychiatric illness. This review will briefly summarise the neuroimmune system in brain development and function, and review the effects of stress and positive environmental experiences during development on neuroimmune function. There are also significant sex differences in how the neuroimmune system responds to environmental experiences early in life, which we will briefly review.
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Affiliation(s)
- Nichola M. Brydges
- Neuroscience and Mental Health Research
Institute, Cardiff University, Cardiff, UK
| | - Jack Reddaway
- Neuroscience and Mental Health Research
Institute, Cardiff University, Cardiff, UK
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9
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Ferle V, Repouskou A, Aspiotis G, Raftogianni A, Chrousos G, Stylianopoulou F, Stamatakis A. Synergistic effects of early life mild adversity and chronic social defeat on rat brain microglia and cytokines. Physiol Behav 2019; 215:112791. [PMID: 31870943 DOI: 10.1016/j.physbeh.2019.112791] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 12/11/2019] [Accepted: 12/12/2019] [Indexed: 01/03/2023]
Abstract
Exposure to early life stress affects the development and function of the brain and when followed by adversities in adulthood, the negative effects of stress are enhanced. Microglia has been proposed as a potential mediator of this phenomenon. In the present study, we investigated the long-term effects of mild early life stress, the consequences of a stressor in adulthood as well as their interaction on microglial and cytokine (PPARγ, IL-1β and TNFα) levels in the brain of adult male rats. As an early life stress we used a model of maternal neglect, in which the dam is present but non-accessible to the pup for 15 min during postnatal days 10-13; as a stressor in adulthood we exposed animals to chronic social defeat (CSD) for 3 weeks. We determined in the hippocampus, prefrontal cortex and amygdala, the number of Iba-1+ microglial cells, the number of PPARγ+ cells as well as the relative expression of PPARγ, IL-1β and TNFα mRNA by qPCR. Following exposure to CSD, the number of Iba-1+ cells was increased in the hippocampus and the prefrontal cortex of adult animals exposed to mild early life stress, while in the absence of CSD no such difference was observed. Moreover, following CSD PPARγ levels were increased in the hippocampus of adult males exposed as neonates to "maternal neglect". Our findings support the notion that early life stress, even a mild one, primes microglia and enhances its reactivity to a second stressful event, later in life, in accord with the "two-hit" hypothesis.
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Affiliation(s)
- Vasiliki Ferle
- Department of Basic Sciences, Faculty of Nursing, School of Health Sciences, National and Kapodistrian University of Athens, Greece
| | - Anastasia Repouskou
- Faculty of Dentistry, School of Health Sciences, National and Kapodistrian University of Athens, Greece.
| | - George Aspiotis
- Department of Basic Sciences, Faculty of Nursing, School of Health Sciences, National and Kapodistrian University of Athens, Greece
| | - Androniki Raftogianni
- Department of Basic Sciences, Faculty of Nursing, School of Health Sciences, National and Kapodistrian University of Athens, Greece
| | - George Chrousos
- Division of Endocrinology, Metabolism and Diabetes, First Department of Pediatrics, Aghia Sofia Children's Hospital, Medical School, National and Kapodistrian University of Athens, Greece.
| | - Fotini Stylianopoulou
- Department of Basic Sciences, Faculty of Nursing, School of Health Sciences, National and Kapodistrian University of Athens, Greece.
| | - Antonios Stamatakis
- Department of Basic Sciences, Faculty of Nursing, School of Health Sciences, National and Kapodistrian University of Athens, Greece.
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10
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Targeted sensory enrichment interventions protect against behavioral and neuroendocrine consequences of early life stress. Psychoneuroendocrinology 2018; 98:74-85. [PMID: 30121011 DOI: 10.1016/j.psyneuen.2018.07.029] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 06/20/2018] [Accepted: 07/29/2018] [Indexed: 12/16/2022]
Abstract
Both basic and clinical research support the use of tactile stimulation to rescue several neurobiobehavioral consequences that follow early life stress. Here, using a translational rodent model of the neonatal intensive care unit (NICU), we tested the individual prophylactic potential of a variety of sensory interventions including tactile (brushing pups with a paint brush to mimic maternal licking), auditory (a simulated lactating rat dam heart beat), and olfactory (a series of aroma therapy scents) stimulation. The NICU model was developed to mimic not only the reduced parental contact that sick infants receive (by isolating rat pups from their litters), but also the nosocomial infections and medical manipulations associated with this experience (by utilizing a dual lipopolysaccharide injection schedule). Each of the neurobiobehavioral consequences observed were dissociable between isolation and inflammation, or required a combined presentation ('two hits') of the neonatal stressors. Sprague-Dawley rats exposed to these early life stressors presented with sex-specific disruptions in both separation-induced ultrasonic vocalization (USV) distress calls (males & females) and juvenile social play USVs (males only). All three sensory enhancement interventions were associated with the rescue of potentiated distress calls while olfactory stimulation was protective of social vocalizations. Female rats exposed to early life stress experienced precocious puberty and shifts in the hypothalamic GnRh axis; sensory enrichment counter-acted the advanced pubertal onset. Animals that underwent the NICU protocol also displayed maturational acceleration in terms of the loss of the rooting reflex in addition to hyperalgesia, a reduced preference for a novel conspecific, blunted basal plasma corticosterone and reduced hippocampal glucocorticoid receptor expression. These alterations closely simulated the clinical effects of early life adversity in terms of disruptions in the hypothalamic pituitary "stress" axis, social communication and engagement, tactile system processing, and accelerated maturation. Moreover, sensory enrichment attenuated many of these behavioral and neurophysiological alterations, and even slowed maturation. Overall, this supports the translatability of our novel rodent model and its potential utility in understanding how brain maturation and quality of early life experiences may interact to shape the integrity of stress and sensory system development. Future work must determine the appropriate modalities and parameters (e.g. patterning, timing) for effective sensory enrichment interventions.
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11
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Alpaugh M, Galleguillos D, Forero J, Morales LC, Lackey SW, Kar P, Di Pardo A, Holt A, Kerr BJ, Todd KG, Baker GB, Fouad K, Sipione S. Disease-modifying effects of ganglioside GM1 in Huntington's disease models. EMBO Mol Med 2018; 9:1537-1557. [PMID: 28993428 PMCID: PMC5666311 DOI: 10.15252/emmm.201707763] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Huntington's disease (HD) is a progressive neurodegenerative disorder characterized by motor, cognitive and psychiatric problems. Previous studies indicated that levels of brain gangliosides are lower than normal in HD models and that administration of exogenous ganglioside GM1 corrects motor dysfunction in the YAC128 mouse model of HD In this study, we provide evidence that intraventricular administration of GM1 has profound disease-modifying effects across HD mouse models with different genetic background. GM1 administration results in decreased levels of mutant huntingtin, the protein that causes HD, and in a wide array of beneficial effects that include changes in levels of DARPP32, ferritin, Iba1 and GFAP, modulation of dopamine and serotonin metabolism, and restoration of normal levels of glutamate, GABA, L-Ser and D-Ser. Treatment with GM1 slows down neurodegeneration, white matter atrophy and body weight loss in R6/2 mice. Motor functions are significantly improved in R6/2 mice and restored to normal in Q140 mice, including gait abnormalities that are often resistant to treatments. Psychiatric-like and cognitive dysfunctions are also ameliorated by GM1 administration in Q140 and YAC128 mice. The widespread benefits of GM1 administration, at molecular, cellular and behavioural levels, indicate that this ganglioside has strong therapeutic and disease-modifying potential in HD.
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Affiliation(s)
- Melanie Alpaugh
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada.,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Danny Galleguillos
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada.,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Juan Forero
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada
| | | | | | - Preeti Kar
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - Alba Di Pardo
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - Andrew Holt
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - Bradley J Kerr
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Department of Anesthesiology and Pain Medicine, University of Alberta, Edmonton, AB, Canada
| | - Kathryn G Todd
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Glen B Baker
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Karim Fouad
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada
| | - Simonetta Sipione
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada .,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
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12
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Thymelaea lythroides extract attenuates microglial activation and depressive-like behavior in LPS-induced inflammation in adult male rats. Biomed Pharmacother 2018; 99:655-663. [PMID: 29710462 DOI: 10.1016/j.biopha.2018.01.125] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 01/13/2018] [Accepted: 01/24/2018] [Indexed: 12/29/2022] Open
Abstract
Thymelaea lythroides extract is widely used as a traditional folk medicine in Morocco, especially for the treatment of diabetes, rheumatism and Inflammatory disease. The aim of the study is to evaluate the possible effect of methanolic extract of Thymelaea lythroides in repressing the inflammatory responses and long-lasting depression-like behavior associated with neuroinflammation in adult rats after neonatal LPS exposure. Male rat pups were treated systemically with either LPS (250??g/kg) or vehicle (phosphate buffer saline) on postnatal day 14. Six hours later, the LPS groups were assigned to intraperitoneal (ip) injection of Minocycline (50?mg/kg) or Thymelaea lythroides (200?mg/kg). Thereafter, in adulthood (postnatal days 90-97), the spontaneous locomotor activity and depression-like behavior were assessed successively in open field and forced swim tests. The levels of proinflammatory cytokines, oxidative damage, and activation of microglia were determined in the hippocampus (HP) of male rats on (PND90-97). Our results showed that open field hypoactivity and increased immobility period in LPS-induced adult rats were normalized on treatment with Thymelaea lythroides and minocycline. Both treatments attenuate the overactivated microglial cells in the CA1 and CA3 of hippocampus (HP) and significantly reduced the oxidative-nitrosative stress markers and cytokine (TNF ?) production in the HP. Thymelaea lythroides seems to have similar neuroprotective effects to Minocycline, and such protection may be due to: reduction of oxidative stress, upregulation of inflammatory mediators production, antidepressant behavior which all are associated with neuroinflammation.
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13
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Walker DJ, Spencer KA. Glucocorticoid programming of neuroimmune function. Gen Comp Endocrinol 2018; 256:80-88. [PMID: 28728884 DOI: 10.1016/j.ygcen.2017.07.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 07/13/2017] [Accepted: 07/16/2017] [Indexed: 01/15/2023]
Abstract
Throughout life physiological systems strive to maintain homeostasis and these systems are susceptible to exposure to maternal or environmental perturbations, particularly during embryonic development. In some cases, these perturbations may influence genetic and physiological processes that permanently alter the functioning of these physiological systems; a process known as developmental programming. In recent years, the neuroimmune system has garnered attention for its fundamental interactions with key hormonal systems, such as the hypothalamic pituitary adrenal (HPA) axis. The ultimate product of this axis, the glucocorticoid hormones, play a key role in modulating immune responses within the periphery and the CNS as part of the physiological stress response. It is well-established that elevated glucocorticoids induced by developmental stress exert profound short and long-term physiological effects, yet there is relatively little information of how these effects are manifested within the neuroimmune system. Pre and post-natal periods are prime candidates for manipulation in order to uncover the physiological mechanisms that underlie glucocorticoid programming of neuroimmune responses. Understanding the potential programming role of glucocorticoids may be key in uncovering vulnerable windows of CNS susceptibility to stressful experiences during embryonic development and improve our use of glucocorticoids as therapeutics in the treatment of neurodegenerative diseases.
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Affiliation(s)
- David J Walker
- School of Psychology & Neuroscience, University of St Andrews, Fife KY16 9JP, United Kingdom.
| | - Karen A Spencer
- School of Psychology & Neuroscience, University of St Andrews, Fife KY16 9JP, United Kingdom
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14
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Reshetnikov V, Studenikina A, Ryabushkina J, Merkulova T, Bondar N. The impact of early-life stress on the expression of HPA-associated genes in the adult murine brain. BEHAVIOUR 2018. [DOI: 10.1163/1568539x-00003482] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Abstract
Early life is an important period for the development of the nervous system and for the programming of behavioural phenotypes in adulthood. In our study, two types of early-life stress were used: prolonged separation of pups from their mothers (for 3 h/day, maternal separation (MS)) and brief separation (for 15 min/day, handling (HD)). We analysed the effects of early-life stress on behaviour and the expression of HPA-associated genes in the hypothalamus, hippocampus, and frontal cortex of male mice. Adult mice in the MS group demonstrated reduced locomotor activity and deficiencies in spatial long-term memory, while the HD showed no significant changes. Additionally, early-life MS resulted in reduced hippocampal Crhr1 mRNA, increased MR/GR mRNA in the hippocampus and hypothalamus. Both groups, HD and MS, showed increased Avp mRNA in the hypothalamus. Thus, prolonged maternal separation but not brief leads to adverse behavioural changes and influences the expression of HPA-associated genes in a brain region-specific manner.
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Affiliation(s)
- V.V. Reshetnikov
- aLaboratory of Gene Expression Regulation, Institute of Cytology and Genetics, SB RAS, Novosibirsk, Russia
| | - A.A. Studenikina
- aLaboratory of Gene Expression Regulation, Institute of Cytology and Genetics, SB RAS, Novosibirsk, Russia
- bNovosibirsk State Medical University, Novosibirsk, Russia
| | - J.A. Ryabushkina
- aLaboratory of Gene Expression Regulation, Institute of Cytology and Genetics, SB RAS, Novosibirsk, Russia
- cNovosibirsk State University, Novosibirsk, Russia
| | - T.I. Merkulova
- aLaboratory of Gene Expression Regulation, Institute of Cytology and Genetics, SB RAS, Novosibirsk, Russia
- cNovosibirsk State University, Novosibirsk, Russia
| | - N.P. Bondar
- aLaboratory of Gene Expression Regulation, Institute of Cytology and Genetics, SB RAS, Novosibirsk, Russia
- cNovosibirsk State University, Novosibirsk, Russia
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15
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De Luca SN, Ziko I, Dhuna K, Sominsky L, Tolcos M, Stokes L, Spencer SJ. Neonatal overfeeding by small-litter rearing sensitises hippocampal microglial responses to immune challenge: Reversal with neonatal repeated injections of saline or minocycline. J Neuroendocrinol 2017; 29. [PMID: 28983991 DOI: 10.1111/jne.12540] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 08/22/2017] [Accepted: 10/01/2017] [Indexed: 01/08/2023]
Abstract
The early-life period is extremely vulnerable to programming effects from the environment, many of which persist into adulthood. We have previously demonstrated that adult rats overfed as neonates have hypothalamic microglia that are hyper-responsive to an immune challenge, as well as hippocampal microglia that respond less efficiently to learning. We therefore hypothesised that neonatal overfeeding would alter the ability of hippocampal microglia to respond to an immune challenge with lipopolysaccharide (LPS) and that concomitant minocycline, a tetracycline antibiotic that suppresses microglial activity, could restore these responses. We induced neonatal overfeeding by manipulating the litter sizes in which Wistar rat pups were raised, so the pups were suckled in litters of four (neonatally overfed) or 12 (control-fed). We then examined the hippocampal microglial profiles 24 hour after an immune challenge with LPS and found that the neonatally overfed rats had dramatically increased microglial numbers in the hippocampus after immune challenge compared to control-fed rats. Attempts to reverse these effects with minocycline revealed repeated that neonatal injections, whether with minocycline or with saline, markedly suppressed microglial number and density throughout the hippocampus and abolished the difference between the groups in their responses to LPS. These data suggest that neonatal overfeeding not only can have lasting effects on hippocampal immune responses, but also that neonatal exposure to a protocol of repeated injections, irrespective of treatment, has a pronounced long-term impact, highlighting the importance of considering these effects when interpreting experimental data.
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Affiliation(s)
- S N De Luca
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
| | - I Ziko
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
| | - K Dhuna
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
| | - L Sominsky
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
| | - M Tolcos
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
| | - L Stokes
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, UK
| | - S J Spencer
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
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16
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Opioid Self-Administration is Attenuated by Early-Life Experience and Gene Therapy for Anti-Inflammatory IL-10 in the Nucleus Accumbens of Male Rats. Neuropsychopharmacology 2017; 42:2128-2140. [PMID: 28436446 PMCID: PMC5603817 DOI: 10.1038/npp.2017.82] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 04/11/2017] [Accepted: 04/12/2017] [Indexed: 12/28/2022]
Abstract
Early-life conditions can contribute to the propensity for developing neuropsychiatric disease, including substance abuse disorders. However, the long-lasting mechanisms that shape risk or resilience for drug addiction remain unclear. Previous work has shown that a neonatal handling procedure in rats (which promotes enriched maternal care) attenuates morphine conditioning, reduces morphine-induced glial activation, and increases microglial expression of the anti-inflammatory cytokine interleukin-10 (IL-10). We thus hypothesized that anti-inflammatory signaling may underlie the effects of early-life experience on later-life opioid drug-taking. Here we demonstrate that neonatal handling attenuates intravenous self-administration of the opioid remifentanil in a drug-concentration-dependent manner. Transcriptional profiling of the nucleus accumbens (NAc) from handled rats following repeated exposure to remifentanil reveals a suppression of pro-inflammatory cytokine and chemokine gene expression, consistent with an anti-inflammatory phenotype. To determine if anti-inflammatory signaling alters drug-taking behavior, we administered intracranial injections of plasmid DNA encoding IL-10 (pDNA-IL-10) into the NAc of non-handled rats. We discovered that pDNA-IL-10 treatment reduces remifentanil self-administration in a drug-concentration-dependent manner, similar to the effect of handling. In contrast, neither handling nor pDNA-IL-10 treatment alters self-administration of food or sucrose rewards. These collective observations suggest that neuroimmune signaling mechanisms in the NAc are shaped by early-life experience and may modify motivated behaviors for opioid drugs. Moreover, manipulation of the IL-10 signaling pathway represents a novel approach for influencing opioid reinforcement.
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Delpech JC, Wei L, Hao J, Yu X, Madore C, Butovsky O, Kaffman A. Early life stress perturbs the maturation of microglia in the developing hippocampus. Brain Behav Immun 2016; 57:79-93. [PMID: 27301858 PMCID: PMC5010940 DOI: 10.1016/j.bbi.2016.06.006] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2016] [Revised: 05/24/2016] [Accepted: 06/11/2016] [Indexed: 12/22/2022] Open
Abstract
Children exposed to abuse or neglect show abnormal hippocampal development and similar findings have been reported in rodent models. Using brief daily separation (BDS), a mouse model of early life stress, we previously showed that exposure to BDS impairs hippocampal function in adulthood and perturbs synaptic maturation, synaptic pruning, axonal growth and myelination in the developing hippocampus. Given that microglia are involved in these developmental processes, we tested whether BDS impairs microglial activity in the hippocampus of 14 (during BDS) and 28-day old mice (one week after BDS). We found that BDS increased the density and altered the morphology of microglia in the hippocampus of 14-day old pups, effects that were no longer present on postnatal day (PND) 28. Despite the normal cell number and morphology seen at PND28, the molecular signature of hippocampal microglia, assessed using the NanoString immune panel, was altered at both ages. We showed that during normal hippocampal development, microglia undergo significant changes between PND14 and PND28, including reduced cell density, decreased ex vivo phagocytic activity, and an increase in the expression of genes involved in inflammation and cell migration. However, microglia harvested from the hippocampus of 28-day old BDS mice showed an increase in phagocytic activity and reduced expression of genes that normally increase across development. Promoter analysis indicated that alteration in the transcriptional activity of PU.1, Creb1, Sp1, and RelA accounted for most of the transcriptional changes seen during normal microglia development and for most of the BDS-induced changes at PND14 and PND28. These findings are the first to demonstrate that early life stress dysregulates microglial function in the developing hippocampus and to identify key transcription factors that are likely to mediate these changes.
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Affiliation(s)
- Jean-Christophe Delpech
- Department of Psychiatry, Yale University School of Medicine, 300 George Street, Suite 901, New Haven, CT 06511, USA
| | - Lan Wei
- Department of Psychiatry, Yale University School of Medicine, 300 George Street, Suite 901, New Haven, CT 06511, USA
| | - Jin Hao
- Department of Psychiatry, Yale University School of Medicine, 300 George Street, Suite 901, New Haven, CT 06511, USA
| | - Xiaoqing Yu
- W.M. Keck Foundation Biotechnology Resource Laboratory, Yale University, New Haven, CT 06511, USA
| | - Charlotte Madore
- Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Oleg Butovsky
- Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA; Evergrande Center for Immunologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, USA
| | - Arie Kaffman
- Department of Psychiatry, Yale University School of Medicine, 300 George Street, Suite 901, New Haven, CT 06511, USA.
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Hoeijmakers L, Heinen Y, van Dam AM, Lucassen PJ, Korosi A. Microglial Priming and Alzheimer's Disease: A Possible Role for (Early) Immune Challenges and Epigenetics? Front Hum Neurosci 2016; 10:398. [PMID: 27555812 PMCID: PMC4977314 DOI: 10.3389/fnhum.2016.00398] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 07/26/2016] [Indexed: 12/11/2022] Open
Abstract
Neuroinflammation is thought to contribute to Alzheimer's disease (AD) pathogenesis that is, to a large extent, mediated by microglia. Given the tight interaction between the immune system and the brain, peripheral immune challenges can profoundly affect brain function. Indeed, both preclinical and clinical studies have indicated that an aberrant inflammatory response can elicit behavioral impairments and cognitive deficits, especially when the brain is in a vulnerable state, e.g., during early development, as a result of aging, or under disease conditions like AD. However, how exactly peripheral immune challenges affect brain function and whether this is mediated by aberrant microglial functioning remains largely elusive. In this review, we hypothesize that: (1) systemic immune challenges occurring during vulnerable periods of life can increase the propensity to induce later cognitive dysfunction and accelerate AD pathology; and (2) that "priming" of microglial cells is instrumental in mediating this vulnerability. We highlight how microglia can be primed by both neonatal infections as well as by aging, two periods of life during which microglial activity is known to be specifically upregulated. Lasting changes in (the ratios of) specific microglial phenotypes can result in an exaggerated pro-inflammatory cytokine response to subsequent inflammatory challenges. While the resulting changes in brain function are initially transient, a continued and/or excess release of such pro-inflammatory cytokines can activate various downstream cellular cascades known to be relevant for AD. Finally, we discuss microglial priming and the aberrant microglial response as potential target for treatment strategies for AD.
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Affiliation(s)
- Lianne Hoeijmakers
- Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam Amsterdam, Netherlands
| | - Yvonne Heinen
- Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam Amsterdam, Netherlands
| | - Anne-Marie van Dam
- Department of Anatomy and Neurosciences, Neuroscience Campus Amsterdam, VU University Medical Center Amsterdam, Netherlands
| | - Paul J Lucassen
- Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam Amsterdam, Netherlands
| | - Aniko Korosi
- Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam Amsterdam, Netherlands
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Markostamou I, Ioannidis A, Dandi E, Mandyla MA, Nousiopoulou E, Simeonidou C, Spandou E, Tata DA. Maternal separation prior to neonatal hypoxia-ischemia: Impact on emotional aspects of behavior and markers of synaptic plasticity in hippocampus. Int J Dev Neurosci 2016; 52:1-12. [PMID: 27165447 DOI: 10.1016/j.ijdevneu.2016.04.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 04/08/2016] [Accepted: 04/09/2016] [Indexed: 12/20/2022] Open
Abstract
Exposure to early-life stress is associated with long-term alterations in brain and behavior, and may aggravate the outcome of neurological insults. This study aimed at investigating the possible interaction between maternal separation, a model of early stress, and subsequent neonatal hypoxia-ischemia on emotional behavior and markers of synaptic plasticity in hippocampus. Therefore, rat pups (N=60) were maternally separated for a prolonged (MS 180min) or a brief (MS 15min) period during the first six postnatal days, while a control group was left undisturbed. Hypoxia-ischemia was applied to a subgroup of each rearing condition on postnatal day 7. Emotional behavior was examined at three months of age and included assessments of anxiety (elevated plus maze), depression-like behavior (forced swimming) and spontaneous exploration (open field). Synaptic plasticity was evaluated based on BDNF and synaptophysin expression in CA3 and dentate gyrus hippocampal regions. We found that neonatal hypoxia-ischemia caused increased levels of anxiety, depression-like behavior and locomotor activity (ambulation). Higher anxiety levels were also seen in maternally separated rats (MS180min) compared to non-maternally separated rats, but prolonged maternal separation prior to HI did not potentiate the HI-associated effect. No differences among the three rearing conditions were found regarding depression-like behavior or ambulation. Immunohistochemical evaluation of synaptophysin revealed that both prolonged maternal separation (MS180min) and neonatal hypoxia-ischemia significantly reduced its expression in the CA3 and dentate gyrus. Decreases in synaptophysin expression in these areas were not exacerbated in rats that were maternally separated for a prolonged period prior to HI. Regarding BDNF expression, we found a significant decrease in immunoreactivity only in the hypoxic-ischemic rats that were subjected to the prolonged maternal separation paradigm. The above findings suggest that early-life stress prior to neonatal hypoxia-ischemia leads to significant alterations in synaptic plasticity of the dorsal hippocampus during adulthood, but does not exacerbate HI-related changes in emotional behavior.
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Affiliation(s)
- Ioanna Markostamou
- Laboratory of Cognitive Neuroscience, School of Psychology, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Anestis Ioannidis
- Laboratory of Cognitive Neuroscience, School of Psychology, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Evgenia Dandi
- Laboratory of Cognitive Neuroscience, School of Psychology, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Maria-Aikaterini Mandyla
- Laboratory of Cognitive Neuroscience, School of Psychology, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Evangelia Nousiopoulou
- Laboratory of Experimental Neurology & Neuroimmunology, B' Department of Neurology, AHEPA University Hospital, Faculty of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Constantina Simeonidou
- Laboratory of Experimental Physiology, Faculty of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Evangelia Spandou
- Laboratory of Experimental Physiology, Faculty of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece.
| | - Despina A Tata
- Laboratory of Cognitive Neuroscience, School of Psychology, Aristotle University of Thessaloniki, Thessaloniki, Greece.
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20
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Frost JL, Schafer DP. Microglia: Architects of the Developing Nervous System. Trends Cell Biol 2016; 26:587-597. [PMID: 27004698 DOI: 10.1016/j.tcb.2016.02.006] [Citation(s) in RCA: 244] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 02/16/2016] [Accepted: 02/19/2016] [Indexed: 11/18/2022]
Abstract
Microglia are resident macrophages of the central nervous system (CNS), representing 5-10% of total CNS cells. Recent findings reveal that microglia enter the embryonic brain, take up residence before the differentiation of other CNS cell types, and become critical regulators of CNS development. Here, we discuss exciting new work implicating microglia in a range of developmental processes, including regulation of cell number and spatial patterning of CNS cells, myelination, and formation and refinement of neural circuits. Furthermore, we review studies suggesting that these cellular functions result in the modulation of behavior, which has important implications for a variety of neurological disorders.
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Affiliation(s)
- Jeffrey L Frost
- Department of Neurobiology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Dorothy P Schafer
- Department of Neurobiology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605, USA.
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21
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Barth CR, Luft C, Funchal GA, de Oliveira JR, Porto BN, Donadio MVF. LPS-induced neonatal stress in mice affects the response profile to an inflammatory stimulus in an age and sex-dependent manner. Dev Psychobiol 2016; 58:600-13. [PMID: 26956468 DOI: 10.1002/dev.21404] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 02/19/2016] [Indexed: 12/26/2022]
Abstract
The aim of this study is to evaluate the response to an inflammatory stimulus in mice exposed to LPS-induced neonatal stress at different ages and sexes. Balb/c mice were submitted to intraperitoneal injections on postnatal days 3 and 10 with lipopolysaccharide (nLPS) or saline solution (nSal). At 21 or 60 days, either saline solution was injected or an inflammatory stimulus was induced by the injection of 1% carrageenan. Inflammatory cytokines, reactive oxygen species, and neutrophil extracellular traps (NETs) production were measured in peritoneal fluid. LPS-induced neonatal stress can reduce inflammatory cytokines in males and females. An increase in NETs production was observed when 60 day nLPS animals were compared to 21 day mice in both sexes. The ROS production was not affected by neonatal stress. The results shown here indicate that LPS-induced neonatal stress can alter cytokine production in response to inflammatory stimuli at different ages, in a sex-dependent effect. © 2016 Wiley Periodicals, Inc. Dev Psychobiol 58: 600-613, 2016.
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Affiliation(s)
- Cristiane R Barth
- Centro Infant, Institute of Biomedical Research (IPB) Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690, 2° andar, Rio Grande do Sul, Porto Alegre, CEP 90610-000, Brazil.,Cellular and Molecular Biology Graduate Program, Faculty of Biosciences, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
| | - Carolina Luft
- Centro Infant, Institute of Biomedical Research (IPB) Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690, 2° andar, Rio Grande do Sul, Porto Alegre, CEP 90610-000, Brazil.,Laboratory of Research in Cellular Biophysics and Inflammation, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
| | - Giselle A Funchal
- Centro Infant, Institute of Biomedical Research (IPB) Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690, 2° andar, Rio Grande do Sul, Porto Alegre, CEP 90610-000, Brazil.,Cellular and Molecular Biology Graduate Program, Faculty of Biosciences, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
| | - Jarbas R de Oliveira
- Cellular and Molecular Biology Graduate Program, Faculty of Biosciences, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Brazil.,Laboratory of Research in Cellular Biophysics and Inflammation, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
| | - Bárbara N Porto
- Centro Infant, Institute of Biomedical Research (IPB) Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690, 2° andar, Rio Grande do Sul, Porto Alegre, CEP 90610-000, Brazil
| | - Márcio V F Donadio
- Centro Infant, Institute of Biomedical Research (IPB) Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690, 2° andar, Rio Grande do Sul, Porto Alegre, CEP 90610-000, Brazil. .,Cellular and Molecular Biology Graduate Program, Faculty of Biosciences, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Brazil. .,Laboratory of Research in Cellular Biophysics and Inflammation, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Brazil.
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22
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Williamson LL, McKenney EA, Holzknecht ZE, Belliveau C, Rawls JF, Poulton S, Parker W, Bilbo SD. Got worms? Perinatal exposure to helminths prevents persistent immune sensitization and cognitive dysfunction induced by early-life infection. Brain Behav Immun 2016; 51:14-28. [PMID: 26162711 DOI: 10.1016/j.bbi.2015.07.006] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 07/06/2015] [Accepted: 07/06/2015] [Indexed: 02/08/2023] Open
Abstract
The incidence of autoimmune and inflammatory diseases has risen dramatically in post-industrial societies. "Biome depletion" - loss of commensal microbial and multicellular organisms such as helminths (intestinal worms) that profoundly modulate the immune system - may contribute to these increases. Hyperimmune-associated disorders also affect the brain, especially neurodevelopment, and increasing evidence links early-life infection to cognitive and neurodevelopmental disorders. We have demonstrated previously that rats infected with bacteria as newborns display life-long vulnerabilities to cognitive dysfunction, a vulnerability that is specifically linked to long-term hypersensitivity of microglial cell function, the resident immune cells of the brain. Here, we demonstrate that helminth colonization of pregnant dams attenuated the exaggerated brain cytokine response of their offspring to bacterial infection, and that combined with post-weaning colonization of offspring with helminths (consistent with their mothers treatment) completely prevented enduring microglial sensitization and cognitive dysfunction in adulthood. Importantly, helminths had no overt impact on adaptive immune cell subsets, whereas exaggerated innate inflammatory responses in splenic macrophages were prevented. Finally, helminths altered the effect of neonatal infection on the gut microbiome; neonatal infection with Escherichia coli caused a shift from genera within the Actinobacteria and Tenericutes phyla to genera in the Bacteroidetes phylum in rats not colonized with helminths, but helminths attenuated this effect. In sum, these data point toward an inter-relatedness of various components of the biome, and suggest potential mechanisms by which this helminth might exert therapeutic benefits in the treatment of neuroinflammatory and cognitive disorders.
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Affiliation(s)
- Lauren L Williamson
- Department of Psychology & Neuroscience, Duke Institute for Brain Sciences, Duke University, United States
| | | | - Zoie E Holzknecht
- Department of Surgery, Duke University Medical Center, United States
| | - Christine Belliveau
- Department of Psychology & Neuroscience, Duke Institute for Brain Sciences, Duke University, United States
| | - John F Rawls
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, United States
| | - Susan Poulton
- Department of Surgery, Duke University Medical Center, United States
| | - William Parker
- Department of Surgery, Duke University Medical Center, United States
| | - Staci D Bilbo
- Department of Psychology & Neuroscience, Duke Institute for Brain Sciences, Duke University, United States.
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23
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do Prado CH, Narahari T, Holland FH, Lee HN, Murthy SK, Brenhouse HC. Effects of early adolescent environmental enrichment on cognitive dysfunction, prefrontal cortex development, and inflammatory cytokines after early life stress. Dev Psychobiol 2015; 58:482-91. [PMID: 26688108 DOI: 10.1002/dev.21390] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 12/02/2015] [Indexed: 01/11/2023]
Abstract
Early postnatal stress such as maternal separation causes cognitive dysfunction later in life, including working memory deficits that are largely mediated by the prefrontal cortex. Maternal separation in male rats also yields a loss of parvalbumin-containing prefrontal cortex interneurons in adolescence, which may occur via inflammatory or oxidative stress mechanisms. Environmental enrichment can prevent several effects of maternal separation; however, effects of enrichment on prefrontal cortex development are not well understood. Here, we report that enrichment prevented cognitive dysfunction in maternally separated males and females, and prevented elevated circulating pro-inflammatory cytokines that was evident in maternally separated males, but not females. However, enrichment did not prevent parvalbumin loss or adolescent measures of oxidative stress. Significant correlations indicated that adolescents with higher oxidative damage and less prefrontal cortex parvalbumin in adolescence committed more errors on the win-shift task; therefore, maternal separation may affect cognitive dysfunction via aberrant interneuron development. © 2015 Wiley Periodicals, Inc. Dev Psychobiol 58: 482-491, 2016.
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Affiliation(s)
- Carine H do Prado
- Department of Psychology, Northeastern University, Boston, MA.,Developmental Cognitive Neuroscience Research Group (GNCD), Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Tanya Narahari
- Department of Chemical Engineering, Northeastern University, Boston, MA
| | | | - Ha-Neul Lee
- Department of Psychology, Northeastern University, Boston, MA
| | - Shashi K Murthy
- Department of Chemical Engineering, Northeastern University, Boston, MA.,Barnett Institute of Chemical and Biological Analysis, Northeastern University, Boston, MA
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Lucassen PJ, Oomen CA, Naninck EFG, Fitzsimons CP, van Dam AM, Czeh B, Korosi A. Regulation of Adult Neurogenesis and Plasticity by (Early) Stress, Glucocorticoids, and Inflammation. Cold Spring Harb Perspect Biol 2015; 7:a021303. [PMID: 26330520 DOI: 10.1101/cshperspect.a021303] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Exposure to stress is one of the best-known negative regulators of adult neurogenesis (AN). We discuss changes in neurogenesis in relation to exposure to stress, glucocorticoid hormones, and inflammation, with a particular focus on early development and on lasting effects of stress. Although the effects of acute and mild stress on AN are generally brief and can be quickly overcome, chronic exposure or more severe forms of stress can induce longer lasting reductions in neurogenesis that can, however, in part, be overcome by subsequent exposure to exercise, drugs targeting the stress system, and some antidepressants. Exposure to stress, particularly during the sensitive period of early life, may (re)program brain plasticity, in particular, in the hippocampus. This may increase the risk to develop cognitive or anxiety symptoms, common to brain diseases like dementia and depression in which plasticity changes occur, and a normalization of neurogenesis may be required for a successful treatment response and recovery.
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Affiliation(s)
- Paul J Lucassen
- Centre for Neuroscience, Swammerdam Institute of Life Sciences, University of Amsterdam, 1090 GE Amsterdam, The Netherlands
| | - Charlotte A Oomen
- Centre for Neuroscience, Swammerdam Institute of Life Sciences, University of Amsterdam, 1090 GE Amsterdam, The Netherlands
| | - Eva F G Naninck
- Centre for Neuroscience, Swammerdam Institute of Life Sciences, University of Amsterdam, 1090 GE Amsterdam, The Netherlands
| | - Carlos P Fitzsimons
- Centre for Neuroscience, Swammerdam Institute of Life Sciences, University of Amsterdam, 1090 GE Amsterdam, The Netherlands
| | - Anne-Marie van Dam
- VU University Medical Center, Department of Anatomy & Neurosciences, 1007 MB Amsterdam, The Netherlands
| | - Boldizsár Czeh
- MTA-PTE, Neurobiology of Stress Research Group, University of Pecs, 7624 Pecs, Hungary Structural Neurobiology Research Group, Szentagothai Janos Research Center, University of Pecs, 7624 Pecs, Hungary
| | - Aniko Korosi
- Centre for Neuroscience, Swammerdam Institute of Life Sciences, University of Amsterdam, 1090 GE Amsterdam, The Netherlands
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25
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Microglia Function in Central Nervous System Development and Plasticity. Cold Spring Harb Perspect Biol 2015; 7:a020545. [PMID: 26187728 DOI: 10.1101/cshperspect.a020545] [Citation(s) in RCA: 238] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The nervous system comprises a remarkably diverse and complex network of different cell types, which must communicate with one another with speed, reliability, and precision. Thus, the developmental patterning and maintenance of these cell populations and their connections with one another pose a rather formidable task. Emerging data implicate microglia, the resident myeloid-derived cells of the central nervous system (CNS), in the spatial patterning and synaptic wiring throughout the healthy, developing, and adult CNS. Importantly, new tools to specifically manipulate microglia function have revealed that these cellular functions translate, on a systems level, to effects on overall behavior. In this review, we give a historical perspective of work to identify microglia function in the healthy CNS and highlight exciting new work in the field that has identified roles for these cells in CNS development, maintenance, and plasticity.
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Hoogland ICM, Houbolt C, van Westerloo DJ, van Gool WA, van de Beek D. Systemic inflammation and microglial activation: systematic review of animal experiments. J Neuroinflammation 2015; 12:114. [PMID: 26048578 PMCID: PMC4470063 DOI: 10.1186/s12974-015-0332-6] [Citation(s) in RCA: 609] [Impact Index Per Article: 67.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 05/26/2015] [Indexed: 12/20/2022] Open
Abstract
Background Animal studies show that peripheral inflammatory stimuli may activate microglial cells in the brain implicating an important role for microglia in sepsis-associated delirium. We systematically reviewed animal experiments related to the effects of systemic inflammation on the microglial and inflammatory response in the brain. Methods We searched PubMed between January 1, 1950 and December 1, 2013 and Embase between January 1, 1988 and December 1, 2013 for animal studies on the influence of peripheral inflammatory stimuli on microglia and the brain. Identified studies were systematically scored on methodological quality. Two investigators extracted independently data on animal species, gender, age, and genetic background; number of animals; infectious stimulus; microglial cells; and other inflammatory parameters in the brain, including methods, time points after inoculation, and brain regions. Results Fifty-one studies were identified of which the majority was performed in mice (n = 30) or in rats (n = 19). Lipopolysaccharide (LPS) (dose ranging between 0.33 and 200 mg/kg) was used as a peripheral infectious stimulus in 39 studies (76 %), and live or heat-killed pathogens were used in 12 studies (24 %). Information about animal characteristics such as species, strain, sex, age, and weight were defined in 41 studies (80 %), and complete methods of the disease model were described in 35 studies (68 %). Studies were also heterogeneous with respect to methods used to assess microglial activation; markers used mostly were the ionized calcium binding adaptor molecule-1 (Iba-1), cluster of differentiation 68 (CD68), and CD11b. After LPS challenge microglial activation was seen 6 h after challenge and remained present for at least 3 days. Live Escherichia coli resulted in microglial activation after 2 days, and heat-killed bacteria after 2 weeks. Concomitant with microglial response, inflammatory parameters in the brain were reviewed in 23 of 51 studies (45 %). Microglial activation was associated with an increase in Toll-like receptor (TLR-2 and TLR-4), tumor necrosis factor alpha (TNF-α), and interleukin 1 beta (IL-1β) messenger ribonucleic acid (mRNA) expression or protein levels. Interpretation Animal experiments robustly showed that peripheral inflammatory stimuli cause microglial activation. We observed distinct differences in microglial activation between systemic stimulation with (supranatural doses) LPS and live or heat-killed bacteria.
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Affiliation(s)
- Inge C M Hoogland
- Department of Neurology, Center of Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| | - Carin Houbolt
- Department of Neurology, Center of Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| | | | - Willem A van Gool
- Department of Neurology, Center of Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| | - Diederik van de Beek
- Department of Neurology, Center of Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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Tracing the trajectory of behavioral impairments and oxidative stress in an animal model of neonatal inflammation. Neuroscience 2015; 298:455-66. [PMID: 25934038 DOI: 10.1016/j.neuroscience.2015.04.048] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 04/20/2015] [Accepted: 04/21/2015] [Indexed: 11/21/2022]
Abstract
Exposure to early-life inflammation results in time-of-challenge-dependent changes in both brain and behavior. The consequences of this neural and behavioral reprogramming are most often reported in adulthood. However, the trajectory for the expression of these various changes is not well delineated, particularly between the juvenile and adult phases of development. Moreover, interventions to protect against these neurodevelopmental disruptions are rarely evaluated. Here, female Sprague-Dawley rats were housed in either environmental enrichment (EE) or standard care (SC) and their male and female offspring were administered 50 μg/kg i.p. of lipopolysaccharide (LPS) or pyrogen-free saline in a dual-administration neonatal protocol. All animals maintained their respective housing assignments from breeding until the end of the study. LPS exposure on postnatal days (P) 3 and 5 of life resulted in differential expression of emotional and cognitive disruptions and evidence of oxidative stress across development. Specifically, social behavior was reduced in neonatal-treated (n)LPS animals at adolescence (P40), but not adulthood (P70). In contrast, male nLPS rats exhibited intact spatial memory as adolescents which was impaired in later life. Moreover, these males had decreased prefrontal cortex levels of glutathione at P40, which was normalized in adult animals. Notably, EE appeared to offer some protection against the consequences of inflammation on juvenile social behavior and fully prevented reduced glutathione levels in the juvenile prefrontal cortex. Combined, these time-dependent effects provide evidence that early-life inflammation interacts with other developmental variables, specifically puberty and EE, in the expression (and prevention) of select behavioral and molecular programs.
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Liaudat AC, Rodríguez N, Chen S, Romanini MC, Vivas A, Rolando A, Gauna H, Mayer N. Adrenal response of male rats exposed to prenatal stress and early postnatal stimulation. Biotech Histochem 2015; 90:432-8. [PMID: 25867787 DOI: 10.3109/10520295.2015.1019926] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Stress in pregnant rats caused by chronic immobilization alters the pattern of secretion of corticosterone and modifies the hypothalamic-pituitary-adrenal axis (HPA) of the fetus. Early postnatal handling, however, may reverse the effects of increased secretion of corticosterone. We investigated the effects of prenatal stress and postnatal handling on the activity of the HPA axis of male offspring of stressed female rats. Male 90-day-old rats from four groups were investigated: prenatally stressed animals without postnatal handling, prenatally stressed animals with postnatal handling, unstressed control animals with postnatal handling, and unstressed control animals without postnatal handling. After sacrifice, the adrenal glands were weighed to determine the adrenal-somatic index. Apoptosis was evaluated by TUNEL assay and active caspase-3 expression. We found that the adrenal gland cortex:medulla ratio increased in animals with prenatal stress and that eventually the stress caused apoptosis. Handling newborns to simulate maternal activity ameliorated some of the negative effects of prenatal stress.
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Affiliation(s)
- A C Liaudat
- Department of Molecular Biology, School of Exact, Physical-Chemical and Natural Sciences, National University of Río Cuarto , Río Cuarto , Argentina
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Hoeijmakers L, Lucassen PJ, Korosi A. The interplay of early-life stress, nutrition, and immune activation programs adult hippocampal structure and function. Front Mol Neurosci 2015; 7:103. [PMID: 25620909 PMCID: PMC4288131 DOI: 10.3389/fnmol.2014.00103] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 12/16/2014] [Indexed: 01/08/2023] Open
Abstract
Early-life adversity increases the vulnerability to develop psychopathologies and cognitive decline later in life. This association is supported by clinical and preclinical studies. Remarkably, experiences of stress during this sensitive period, in the form of abuse or neglect but also early malnutrition or an early immune challenge elicit very similar long-term effects on brain structure and function. During early-life, both exogenous factors like nutrition and maternal care, as well as endogenous modulators, including stress hormones and mediator of immunological activity affect brain development. The interplay of these key elements and their underlying molecular mechanisms are not fully understood. We discuss here the hypothesis that exposure to early-life adversity (specifically stress, under/malnutrition and infection) leads to life-long alterations in hippocampal-related cognitive functions, at least partly via changes in hippocampal neurogenesis. We further discuss how these different key elements of the early-life environment interact and affect one another and suggest that it is a synergistic action of these elements that shapes cognition throughout life. Finally, we consider different intervention studies aiming to prevent these early-life adversity induced consequences. The emerging evidence for the intriguing interplay of stress, nutrition, and immune activity in the early-life programming calls for a more in depth understanding of the interaction of these elements and the underlying mechanisms. This knowledge will help to develop intervention strategies that will converge on a more complete set of changes induced by early-life adversity.
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Affiliation(s)
- Lianne Hoeijmakers
- Center for Neuroscience, Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam, Netherlands
| | - Paul J Lucassen
- Center for Neuroscience, Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam, Netherlands
| | - Aniko Korosi
- Center for Neuroscience, Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam, Netherlands
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30
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Zakharova LA. Perinatal stress in brain programming and pathogenesis of psychoneurological disorders. BIOL BULL+ 2015. [DOI: 10.1134/s1062359015010124] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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31
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Tata DA, Markostamou I, Ioannidis A, Gkioka M, Simeonidou C, Anogianakis G, Spandou E. Effects of maternal separation on behavior and brain damage in adult rats exposed to neonatal hypoxia-ischemia. Behav Brain Res 2014; 280:51-61. [PMID: 25433094 DOI: 10.1016/j.bbr.2014.11.033] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 10/15/2014] [Accepted: 11/20/2014] [Indexed: 12/17/2022]
Abstract
Animal studies suggest that maternal separation, a widely used paradigm to study the effects of early life adversity, exerts a profound and life-long impact on both brain and behavior. The aim of the current study was to investigate whether adverse early life experiences interact with neonatal hypoxia-ischemia, affecting the outcome of this neurological insult at both functional and structural levels during adulthood. Rat pups were separated from their mothers during postnatal days 1-6, for either a short (15 min) or prolonged (180 min) period, while another group was left undisturbed. On postnatal day 7, a subgroup from each of the three postnatal manipulations was exposed to a hypoxic-ischemic episode. Behavioral examination took place approximately at three months of age and included tests of learning and memory (Morris water maze, novel object and novel place recognition), as well as motor coordination (rota-rod). We found that both prolonged maternal separation and neonatal hypoxia-ischemia impaired the animals' spatial learning and reference memory. Deficits in spatial but not visual recognition memory were detected only in hypoxic-ischemic rats. Interestingly, prolonged maternal separation prior to neonatal hypoxia-ischemia augmented the reference memory impairments. Histological analysis of infarct size, hippocampal area and thickness of corpus callosum did not reveal any exacerbation of damage in hypoxic-ischemic rats that were maternally separated for a prolonged period. These are the first data suggesting that an adverse postnatal environmental manipulation of just 6 days causes long-term effects on spatial learning and memory and may render the organism more vulnerable to a subsequent insult.
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Affiliation(s)
- Despina A Tata
- School of Psychology, Aristotle University of Thessaloniki, Thessaloniki, Greece.
| | - Ioanna Markostamou
- School of Psychology, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Anestis Ioannidis
- School of Psychology, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Mara Gkioka
- School of Psychology, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Constantina Simeonidou
- Laboratory of Experimental Physiology, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Georgios Anogianakis
- Laboratory of Experimental Physiology, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Evangelia Spandou
- Laboratory of Experimental Physiology, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece.
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Johnson RR, Maldonado Bouchard S, Prentice TW, Bridegam P, Rassu F, Young CR, Steelman AJ, Welsh TH, Welsh CJ, Meagher MW. Neonatal experience interacts with adult social stress to alter acute and chronic Theiler's virus infection. Brain Behav Immun 2014; 40:110-20. [PMID: 24632225 DOI: 10.1016/j.bbi.2014.03.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 02/19/2014] [Accepted: 03/03/2014] [Indexed: 12/30/2022] Open
Abstract
Previous research has shown that neonatal handling has prolonged protective effects associated with stress resilience and aging, yet little is known about its effect on stress-induced modulation of infectious disease. We have previously demonstrated that social disruption stress exacerbates the acute and chronic phases of the disease when applied prior to Theiler's virus infection (PRE-SDR) whereas it attenuates disease severity when applied concurrently with infection (CON-SDR). Here, we asked whether neonatal handling would protect adult mice from the detrimental effects of PRE-SDR and attenuate the protective effects of CON-SDR on Theiler's virus infection. As expected, handling alone decreased IL-6 and corticosterone levels, protected the non-stressed adult mice from motor impairment throughout infection and reduced antibodies to myelin components (PLP, MBP) during the autoimmune phase of disease. In contrast, neonatal handling X PRE/CON-SDR elevated IL-6 and reduced corticosterone as well as increased motor impairment during the acute phase of the infection. Neonatal handling X PRE/CON-SDR continued to exacerbate motor impairment during the chronic phase, whereas only neonatal handling X PRE-SDR increased in antibodies to PLP, MOG, MBP and TMEV. Together, these results imply that while handling reduced the severity of later Theiler's virus infection in non-stressed mice, brief handling may not be protective when paired with later social stress.
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Affiliation(s)
- R R Johnson
- Advanced brain Monitoring, Inc, Carlsbad, CA 92008, United States
| | - S Maldonado Bouchard
- Department of Psychology, College of Liberal Arts, Texas A&M University, United States; Texas A&M Institute for Neuroscience, Texas A&M University, College Station, TX 77843, United States
| | - T W Prentice
- Department of Psychology, College of Liberal Arts, Texas A&M University, United States
| | - P Bridegam
- Department of Psychology, College of Liberal Arts, Texas A&M University, United States
| | - F Rassu
- Department of Psychology, College of Liberal Arts, Texas A&M University, United States
| | - C R Young
- Departments of Veterinary Integrative Biosciences and Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, United States
| | - A J Steelman
- Departments of Veterinary Integrative Biosciences and Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, United States
| | - T H Welsh
- Department of Animal Science, College of Agriculture and Life Sciences, Texas A&M University, United States
| | - C J Welsh
- Departments of Veterinary Integrative Biosciences and Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, United States
| | - M W Meagher
- Department of Psychology, College of Liberal Arts, Texas A&M University, United States.
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33
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Modulation of adult hippocampal neurogenesis by early-life environmental challenges triggering immune activation. Neural Plast 2014; 2014:194396. [PMID: 24891958 PMCID: PMC4033517 DOI: 10.1155/2014/194396] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 04/11/2014] [Indexed: 02/03/2023] Open
Abstract
The immune system plays an important role in the communication between the human body and the environment, in early development as well as in adulthood. Per se, research has shown that factors such as maternal stress and nutrition as well as maternal infections can activate the immune system in the infant. A rising number of research studies have shown that activation of the immune system in early life can augment the risk of some psychiatric disorders in adulthood, such as schizophrenia and depression. The mechanisms of such a developmental programming effect are unknown; however some preliminary evidence is emerging in the literature, which suggests that adult hippocampal neurogenesis may be involved. A growing number of studies have shown that pre- and postnatal exposure to an inflammatory stimulus can modulate the number of proliferating and differentiating neural progenitors in the adult hippocampus, and this can have an effect on behaviours of relevance to psychiatric disorders. This review provides a summary of these studies and highlights the evidence supporting a neurogenic hypothesis of immune developmental programming.
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34
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Williamson LL, Bilbo SD. Neonatal infection modulates behavioral flexibility and hippocampal activation on a Morris Water Maze task. Physiol Behav 2014; 129:152-9. [PMID: 24576680 PMCID: PMC4005787 DOI: 10.1016/j.physbeh.2014.02.033] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 10/29/2013] [Accepted: 02/12/2014] [Indexed: 10/25/2022]
Abstract
Neonatal infection has enduring effects on the brain, both at the cellular and behavioral levels. We determined the effects of peripheral infection with Escherichia coli at postnatal day (P) 4 in rats on a water maze task in adulthood, and assessed neuronal activation in the dentate gyrus (DG) following the memory test. Rats were trained and tested on one of 3 distinct water maze task paradigms: 1) minimal training (18 trials/3days), 2) extended training (50 trials/10days) or 3) reversal training (extended training followed by 30 trials/3days with a new platform location). Following a 48h memory test, brains were harvested to assess neuronal activation using activity-regulated cytoskeleton-associated (Arc) protein in the DG. Following minimal training, rats treated neonatally with E. coli had improved performance and paradoxically reduced Arc expression during the memory test compared to control rats treated with PBS early in life. However, neonatally-infected rats did not differ from control rats in behavior or neuronal activation during the memory test following extended training. Furthermore, rats treated neonatally with E. coli were significantly impaired during the 48h memory test for a reversal platform location, unlike controls. Specifically, whereas neonatally-infected rats were able to acquire the new location at the same rate as controls, they spent significantly less time in the target quadrant for the reversal platform during a memory test. However, neonatally-infected and control rats had similar levels of Arc expression following the 48h memory test for reversal. Together, these data indicate that neonatal infection may improve the rate of acquisition on hippocampal-dependent tasks while impairing flexibility on the same tasks; in addition, network activation in the DG during learning may be predictive of future cognitive flexibility on a hippocampal-dependent task.
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Affiliation(s)
- Lauren L Williamson
- Department of Psychology & Neuroscience, Duke University, Durham, NC 27708, United States.
| | - Staci D Bilbo
- Department of Psychology & Neuroscience, Duke University, Durham, NC 27708, United States
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35
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Singhal G, Jaehne EJ, Corrigan F, Baune BT. Cellular and molecular mechanisms of immunomodulation in the brain through environmental enrichment. Front Cell Neurosci 2014; 8:97. [PMID: 24772064 PMCID: PMC3982075 DOI: 10.3389/fncel.2014.00097] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 03/14/2014] [Indexed: 11/17/2022] Open
Abstract
Recent studies on environmental enrichment (EE) have shown cytokines, cellular immune components [e.g., T lymphocytes, natural killer (NK) cells], and glial cells in causal relationship to EE in bringing out changes to neurobiology and behavior. The purpose of this review is to evaluate these neuroimmune mechanisms associated with neurobiological and behavioral changes in response to different EE methods. We systematically reviewed common research databases. After applying all inclusion and exclusion criteria, 328 articles remained for this review. Physical exercise (PE), a form of EE, elicits anti-inflammatory and neuromodulatory effects through interaction with several immune pathways including interleukin (IL)-6 secretion from muscle fibers, reduced expression of Toll-like receptors on monocytes and macrophages, reduced secretion of adipokines, modulation of hippocampal T cells, priming of microglia, and upregulation of mitogen-activated protein kinase phosphatase-1 in central nervous system. In contrast, immunomodulatory roles of other enrichment methods are not studied extensively. Nonetheless, studies showing reduction in the expression of IL-1β and tumor necrosis factor-α in response to enrichment with novel objects and accessories suggest anti-inflammatory effects of novel environment. Likewise, social enrichment, though considered a necessity for healthy behavior, results in immunosuppression in socially defeated animals. This has been attributed to reduction in T lymphocytes, NK cells and IL-10 in subordinate animals. EE through sensory stimuli has been investigated to a lesser extent and the effect on immune factors has not been evaluated yet. Discovery of this multidimensional relationship between immune system, brain functioning, and EE has paved a way toward formulating environ-immuno therapies for treating psychiatric illnesses with minimal use of pharmacotherapy. While the immunomodulatory role of PE has been evaluated extensively, more research is required to investigate neuroimmune changes associated with other enrichment methods.
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Affiliation(s)
- Gaurav Singhal
- Psychiatric Neuroscience Lab, Discipline of Psychiatry, School of Medicine, University of AdelaideAdelaide, SA, Australia
| | - Emily J. Jaehne
- Psychiatric Neuroscience Lab, Discipline of Psychiatry, School of Medicine, University of AdelaideAdelaide, SA, Australia
| | - Frances Corrigan
- Discipline of Anatomy and Physiology, School of Medical Sciences, University of AdelaideAdelaide, SA, Australia
| | - Bernhard T. Baune
- Psychiatric Neuroscience Lab, Discipline of Psychiatry, School of Medicine, University of AdelaideAdelaide, SA, Australia
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Abstract
Every year, more cases of sepsis appear in intensive care units. The most frequent complication of sepsis is septic encephalopathy (SE), which is also the essential determinant of mortality. Despite many years of research, it still is not known at which stage of sepsis the first signs of SE appear; however, it is considered the most frequent form of encephalopathy. Patients have dysfunction of cognitive abilities and consciousness, and sometimes even epileptic seizures. Despite intensive treatment, the effects of SE remain for many years and constitute an important social problem. Numerous studies indicate that changes in the brain involve free radicals, nitric oxide, increased synthesis of inflammatory factors, disturbances in cerebral circulation, microthromboses, and ischemia, which cause considerable neuronal destruction in different areas of the brain. To determine at what point during sepsis the first signs of SE appear, different experimental models are needed to detect the aforementioned changes and to select the proper therapy for this syndrome.
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Affiliation(s)
- Marek Ziaja
- Department of Histology, Jagiellonian University Medical College, Kraków, Poland.
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37
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Gareau MG. Microbiota-gut-brain axis and cognitive function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 817:357-71. [PMID: 24997042 DOI: 10.1007/978-1-4939-0897-4_16] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Recent studies have demonstrated a clear association between changes in the microbiota and cognitive behavior. Intestinal dysbiosis, as modeled using GF mice (containing no microbiota), bacterial infection with an enteric pathogen, and administration of probiotics, can modulate cognitive behavior including learning and memory. This chapter will highlight recent findings in both human and animal studies indicating how changes in the composition and diversity of the microbiota can impact behavior and brain physiology in both disease states and in health. Cognitive behavior can not only be affected in cases of intestinal disease, but also manifests changes in extra-intestinal disease conditions.
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Affiliation(s)
- Mélanie G Gareau
- Department of Medicine, University of California, San Diego, 9500 Gilman Dr #0063, La Jolla, CA, 92093, USA,
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Neonatal E. coli infection causes neuro-behavioral deficits associated with hypomyelination and neuronal sequestration of iron. J Neurosci 2013; 33:16334-45. [PMID: 24107964 DOI: 10.1523/jneurosci.0708-13.2013] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Recent evidence indicates that inflammatory insults in neonates significantly influenced white matter development and caused behavioral deficits that manifest in young adulthood. The mechanisms underlying these developmental and behavioral complications, however, are not well understood. We hypothesize that acute brain inflammation caused by neonatal infection reduces the bioavailability of iron required for oligodendrocyte maturation and white matter development. Here, we confirm that peripheral Escherichia coli infection in neonates at postnatal day 3 (P3) caused acute brain inflammation that was resolved within 72 h. Nonetheless, transient early life infection (ELI) profoundly influenced behavior, white matter development, and iron homeostasis in the brain. For instance, mice exposed to E. coli as neonates had increased locomotor activity and impaired motor coordination as juveniles (P35) and young adults (P60). In addition, these behavioral deficits were associated with marked hypomyelination and a reduction of oligodendrocytes in subcortical white matter and motor cortex. Moreover, ELI altered transcripts related to cellular sequestration of iron in the brain including hepcidin, ferroportin, and L-ferritin. For example, ELI increased hepcidin mRNA and decreased ferroportin mRNA and protein in the brain at P4, which preceded increased L-ferritin mRNA at P12. Consistent with the mRNA results, L-ferritin protein was robustly increased at P12 specifically in neurons of E. coli infected mice. We interpret these data to indicate that neonatal infection causes significant neuronal sequestration of iron at a time point before myelination. Together, these data indicate a possible role for aberrant neuronal iron storage in neonatal infection-induced disturbances in myelination and behavior.
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39
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Early handling effect on female rat spatial and non-spatial learning and memory. Behav Processes 2013; 103:9-16. [PMID: 24216081 DOI: 10.1016/j.beproc.2013.10.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 10/11/2013] [Accepted: 10/27/2013] [Indexed: 01/11/2023]
Abstract
This study aims at providing an insight into early handling procedures on learning and memory performance in adult female rats. Early handling procedures were started on post-natal day 2 until 21, and consisted in 15 min, daily separations of the dams from their litters. Assessment of declarative memory was carried out in the novel-object recognition task; spatial learning, reference- and working memory were evaluated in the Morris water maze (MWM). Our results indicate that early handling induced an enhancement in: (1) declarative memory, in the object recognition task, both at 1h and 24h intervals; (2) reference memory in the probe test and working memory and behavioral flexibility in the "single-trial and four-trial place learning paradigm" of the MWM. Short-term separation by increasing maternal care causes a dampening in HPA axis response in the pups. A modulated activation of the stress response may help to protect brain structures, involved in cognitive function. In conclusion, this study shows the long-term effects of a brief maternal separation in enhancing object recognition-, spatial reference- and working memory in female rats, remarking the impact of early environmental experiences and the consequent maternal care on the behavioral adaptive mechanisms in adulthood.
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Bolton JL, Huff NC, Smith SH, Mason SN, Foster WM, Auten RL, Bilbo SD. Maternal stress and effects of prenatal air pollution on offspring mental health outcomes in mice. ENVIRONMENTAL HEALTH PERSPECTIVES 2013; 121:1075-82. [PMID: 23823752 PMCID: PMC3764088 DOI: 10.1289/ehp.1306560] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 07/01/2013] [Indexed: 05/13/2023]
Abstract
BACKGROUND Low socioeconomic status is consistently associated with reduced physical and mental health, but the mechanisms remain unclear. Increased levels of urban air pollutants interacting with parental stress have been proposed to explain health disparities in respiratory disease, but the impact of such interactions on mental health is unknown. OBJECTIVES We aimed to determine whether prenatal air pollution exposure and stress during pregnancy act synergistically on offspring to induce a neuroinflammatory response and subsequent neurocognitive disorders in adulthood. METHODS Mouse dams were intermittently exposed via oropharyngeal aspiration to diesel exhaust particles (DEP; 50 μg × 6 doses) or vehicle throughout gestation. This exposure was combined with standard housing or nest material restriction (NR; a novel model of maternal stress) during the last third of gestation. RESULTS Adult (postnatal day 60) offspring of dams that experienced both stressors (DEP and NR) displayed increased anxiety, but only male offspring of this group had impaired cognition. Furthermore, maternal DEP exposure increased proinflammatory interleukin (IL)-1β levels within the brains of adult males but not females, and maternal DEP and NR both decreased anti-inflammatory IL-10 in male, but not female, brains. Similarly, only DEP/NR males showed increased expression of the innate immune recognition gene toll-like receptor 4 (Tlr4) and its downstream effector, caspase-1. CONCLUSIONS These results show that maternal stress during late gestation increases the susceptibility of offspring-particularly males-to the deleterious effects of prenatal air pollutant exposure, which may be due to a synergism of these factors acting on innate immune recognition genes and downstream neuroinflammatory cascades within the developing brain.
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Affiliation(s)
- Jessica L Bolton
- Department of Psychology and Neuroscience, Duke University, Durham, North Carolina 27710, USA.
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Functional programming of the autonomic nervous system by early life immune exposure: implications for anxiety. PLoS One 2013; 8:e57700. [PMID: 23483921 PMCID: PMC3590226 DOI: 10.1371/journal.pone.0057700] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Accepted: 01/23/2013] [Indexed: 12/13/2022] Open
Abstract
Neonatal exposure of rodents to an immune challenge alters a variety of behavioural and physiological parameters in adulthood. In particular, neonatal lipopolysaccharide (LPS; 0.05 mg/kg, i.p.) exposure produces robust increases in anxiety-like behaviour, accompanied by persistent changes in hypothalamic-pituitary-adrenal (HPA) axis functioning. Altered autonomic nervous system (ANS) activity is an important physiological contributor to the generation of anxiety. Here we examined the long term effects of neonatal LPS exposure on ANS function and the associated changes in neuroendocrine and behavioural indices. ANS function in Wistar rats, neonatally treated with LPS, was assessed via analysis of tyrosine hydroxylase (TH) in the adrenal glands on postnatal days (PNDs) 50 and 85, and via plethysmographic assessment of adult respiratory rate in response to mild stress (acoustic and light stimuli). Expression of genes implicated in regulation of autonomic and endocrine activity in the relevant brain areas was also examined. Neonatal LPS exposure produced an increase in TH phosphorylation and activity at both PNDs 50 and 85. In adulthood, LPS-treated rats responded with increased respiratory rates to the lower intensities of stimuli, indicative of increased autonomic arousal. These changes were associated with increases in anxiety-like behaviours and HPA axis activity, alongside altered expression of the GABA-A receptor α2 subunit, CRH receptor type 1, CRH binding protein, and glucocorticoid receptor mRNA levels in the prefrontal cortex, hippocampus and hypothalamus. The current findings suggest that in addition to the commonly reported alterations in HPA axis functioning, neonatal LPS challenge is associated with a persistent change in ANS activity, associated with, and potentially contributing to, the anxiety-like phenotype. The findings of this study reflect the importance of changes in the perinatal microbial environment on the ontogeny of physiological processes.
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Bilbo SD, Schwarz JM. The immune system and developmental programming of brain and behavior. Front Neuroendocrinol 2012; 33:267-86. [PMID: 22982535 PMCID: PMC3484177 DOI: 10.1016/j.yfrne.2012.08.006] [Citation(s) in RCA: 396] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 08/28/2012] [Accepted: 08/29/2012] [Indexed: 12/16/2022]
Abstract
The brain, endocrine, and immune systems are inextricably linked. Immune molecules have a powerful impact on neuroendocrine function, including hormone-behavior interactions, during health as well as sickness. Similarly, alterations in hormones, such as during stress, can powerfully impact immune function or reactivity. These functional shifts are evolved, adaptive responses that organize changes in behavior and mobilize immune resources, but can also lead to pathology or exacerbate disease if prolonged or exaggerated. The developing brain in particular is exquisitely sensitive to both endogenous and exogenous signals, and increasing evidence suggests the immune system has a critical role in brain development and associated behavioral outcomes for the life of the individual. Indeed, there are associations between many neuropsychiatric disorders and immune dysfunction, with a distinct etiology in neurodevelopment. The goal of this review is to describe the important role of the immune system during brain development, and to discuss some of the many ways in which immune activation during early brain development can affect the later-life outcomes of neural function, immune function, mood and cognition.
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Affiliation(s)
- Staci D Bilbo
- Department of Psychology and Neuroscience, Duke University, 572 Research Drive, Box 91050, Durham, NC 27708, USA.
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Bolton JL, Smith SH, Huff NC, Gilmour MI, Foster WM, Auten RL, Bilbo SD. Prenatal air pollution exposure induces neuroinflammation and predisposes offspring to weight gain in adulthood in a sex‐specific manner. FASEB J 2012; 26:4743-54. [DOI: 10.1096/fj.12-210989] [Citation(s) in RCA: 164] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Jessica L. Bolton
- Department of Psychology and NeuroscienceDuke UniversityDurhamNorth CarolinaUSA
| | - Susan H. Smith
- Department of Psychology and NeuroscienceDuke UniversityDurhamNorth CarolinaUSA
| | - Nicole C. Huff
- Department of Psychology and NeuroscienceDuke UniversityDurhamNorth CarolinaUSA
| | - M. Ian Gilmour
- Environmental Public Health Division, National Health and Environmental Effects Research LaboratoryU.S. Environmental Protection AgencyResearch Triangle ParkNorth CarolinaUSA
| | - W. Michael Foster
- Department of Medicine, Division of Pulmonary and Critical Care MedicineDuke University Medical CenterDurhamNorth CarolinaUSA
| | - Richard L. Auten
- Department of Pediatrics, Division of Neonatal MedicineDuke University Medical CenterDurhamNorth CarolinaUSA
| | - Staci D. Bilbo
- Department of Psychology and NeuroscienceDuke UniversityDurhamNorth CarolinaUSA
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Bilbo SD, Smith SH, Schwarz JM. A lifespan approach to neuroinflammatory and cognitive disorders: a critical role for glia. J Neuroimmune Pharmacol 2012; 7:24-41. [PMID: 21822589 PMCID: PMC3267003 DOI: 10.1007/s11481-011-9299-y] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 07/14/2011] [Indexed: 12/15/2022]
Abstract
Cognitive decline is a common problem of aging. Whereas multiple neural and glial mechanisms may account for these declines, microglial sensitization and/or dystrophy has emerged as a leading culprit in brain aging and dysfunction. However, glial activation is consistently observed in normal brain aging as well, independent of frank neuroinflammation or functional impairment. Such variability suggests the existence of additional vulnerability factors that can impact neuronal-glial interactions and thus overall brain and cognitive health. The goal of this review is to elucidate our working hypothesis that an individual's risk or resilience to neuroinflammatory disorders and poor cognitive aging may critically depend on their early life experience, which can change immune reactivity within the brain for the remainder of the lifespan. For instance, early-life infection in rats can profoundly disrupt memory function in young adulthood, as well as accelerate age-related cognitive decline, both of which are linked to enduring changes in glial function that occur in response to the initial infection. We discuss these findings within the context of the growing literature on the role of immune molecules and neuroimmune crosstalk in normal brain development. We highlight the intrinsic factors (e.g., chemokines, hormones) that regulate microglial development and their colonization of the embryonic and postnatal brain, and the capacity for disruption or "re-programming" of this crucial process by external events (e.g., stress, infection). An impact on glia, which in turn alters neural development, has the capacity to profoundly impact cognitive and mental health function at all stages of life.
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Affiliation(s)
- Staci D Bilbo
- Department of Psychology & Neuroscience, Duke University, Durham, NC 27708, USA.
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Huang Y, Xu H, Li H, Yang H, Chen Y, Shi X. Pre-gestational stress reduces the ratio of 5-HIAA to 5-HT and the expression of 5-HT1A receptor and serotonin transporter in the brain of foetal rat. BMC Neurosci 2012; 13:22. [PMID: 22373128 PMCID: PMC3311061 DOI: 10.1186/1471-2202-13-22] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 02/28/2012] [Indexed: 12/25/2022] Open
Abstract
Background Many studies have found that stress before or during pregnancy is linked to an increased incidence of behavioural disorders in offspring. However, few studies have investigated hypothalamic-pituitary-adrenal (HPA) axis activity and the serotonergic system as a consequence of pregestational stress. In the present study, we investigated the effect of pre-gestational stress on HPA axis activity in maternal rats and their foetuses and examined whether changes in HPA axis activity of maternal rats produced functional changes in the serotonergic system in the brain of foetuses. Results We used the behavioural tests to assess the model of chronic unpredictable stress (CUS) in maternal rats. We found the activity in the open field and sucrose consumption was lower for rats with CUS than for the controls. Body weight but not brain weight was higher for control foetuses than those from the CUS group. Serum corticosterone and corticotrophin-releasing hormone levels were significantly higher for mothers with CUS before pregnancy and their foetuses than for the controls. Levels of 5-hydroxytryptamine (5-HT) were higher in the hippocampus and hypothalamus of foetuses in the CUS group than in the controls, and 5-hydroxyindoleacetic acid (5-HIAA) levels were lower in the hippocampus in foetuses in the CUS group than in the control group. Levels of 5-HIAA in the hypothalamus did not differ between foetuses in the CUS group and in the control group. The ratio of 5-HIAA to 5-HT was significantly lower for foetuses in the CUS group than in the control group. Levels of 5-HT1A receptor were significantly lower in the foetal hippocampus in the CUS group than in the control group, with no significant difference in the hypothalamus. The levels of serotonin transporter (SERT) were lower in both the foetal hippocampus and foetal hypothalamus in the CUS group than in the control group. Conclusions Our data demonstrate that pre-gestational stress alters HPA axis activity in maternal rats and their foetuses, which is associated with functional changes in 5-HT activity (5-HT, 5-HIAA and ratio of 5-HIAA to 5-HT), as well as the levels of the 5-HT1A receptor and SERT in the hippocampus and hypothalamus of foetuses.
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Affiliation(s)
- Yuejun Huang
- Department of Pediatrics, Second Affiliated Hospital of Medical College of Shantou University, North Dongxia Rd, Shantou 515041, Guangdong, China
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Swanepoel T, Harvey BH, Harden LM, Laburn HP, Mitchell D. Simulated systemic recurrent Mycoplasma infection in rats induces recurrent sickness responses without residual impairment in spatial learning and memory. Physiol Behav 2012; 105:800-8. [DOI: 10.1016/j.physbeh.2011.10.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 09/15/2011] [Accepted: 10/11/2011] [Indexed: 11/28/2022]
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Pinheiro RMC, de Lima MNM, Fries GR, Garcia VA, Presti-Torres J, Hallmenschlager LH, Alcalde LA, Roesler R, Andersen ML, Quevedo J, Kapczinski F, Schröder N. Early life stress exacerbates cognitive dysfunction induced by d-amphetamine: amelioration by valproic acid. J Neural Transm (Vienna) 2012; 119:627-37. [PMID: 22218930 DOI: 10.1007/s00702-011-0754-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 12/20/2011] [Indexed: 12/29/2022]
Abstract
It has been demonstrated that experiences taking place early in life have a profound influence on brain development, interacting with the genetic background and determining differences in the vulnerability to the onset of bipolar disorder when the individual is exposed to a second adverse event later in life. Here, we investigated the effects of exposure to an early adverse life event (maternal deprivation) and to a later adverse life event [D-amphetamine (AMPH)] on cognition in an animal model of mania. We have previously demonstrated that that repeated AMPH exposure produces severe and persistent cognitive impairment, which was more pronounced when the animals were maternal deprived, suggesting that the early adverse life event could be potentiating the effects of the exposure to the second adverse life event later in life. Here, we show that valproic acid ameliorated the cognitive deficits induced by AMPH, but it was not effective when the animals were exposed to both stressors: maternal deprivation and AMPH treatment.
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Affiliation(s)
- Rose Mary Carvalho Pinheiro
- Department of Physiological Sciences, Neurobiology and Developmental Biology Laboratory, Faculty of Biosciences, Pontifical Catholic University, Av Ipiranga, 6681 Prédio 12D, Sala 340, Porto Alegre, RS 90619-900, Brazil
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Abstract
The proinflammatory cytokine interleukin-1β (IL-1β) is critical for normal hippocampus (HP)-dependent cognition, whereas high levels can disrupt memory and are implicated in neurodegeneration. However, the cellular source of IL-1β during learning has not been shown, and little is known about the risk factors leading to cytokine dysregulation within the HP. We have reported that neonatal bacterial infection in rats leads to marked HP-dependent memory deficits in adulthood. However, deficits are only observed if unmasked by a subsequent immune challenge [lipopolysaccharide (LPS)] around the time of learning. These data implicate a long-term change within the immune system that, upon activation with the "second hit," LPS, acutely impacts the neural processes underlying memory. Indeed, inhibiting brain IL-1β before the LPS challenge prevents memory impairment in neonatally infected (NI) rats. We aimed to determine the cellular source of IL-1β during normal learning and thereby lend insight into the mechanism by which this cytokine is enduringly altered by early-life infection. We show for the first time that CD11b(+) enriched cells are the source of IL-1β during normal HP-dependent learning. CD11b(+) cells from NI rats are functionally sensitized within the adult HP and produce exaggerated IL-1β ex vivo compared with controls. However, an exaggerated IL-1β response in vivo requires LPS before learning. Moreover, preventing microglial activation during learning prevents memory impairment in NI rats, even following an LPS challenge. Thus, early-life events can significantly modulate normal learning-dependent cytokine activity within the HP, via a specific, enduring impact on brain microglial function.
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Schwarz JM, Hutchinson MR, Bilbo SD. Early-life experience decreases drug-induced reinstatement of morphine CPP in adulthood via microglial-specific epigenetic programming of anti-inflammatory IL-10 expression. J Neurosci 2011; 31:17835-47. [PMID: 22159099 PMCID: PMC3259856 DOI: 10.1523/jneurosci.3297-11.2011] [Citation(s) in RCA: 150] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 10/26/2011] [Accepted: 10/26/2011] [Indexed: 01/29/2023] Open
Abstract
A critical component of drug addiction research involves identifying novel biological mechanisms and environmental predictors of risk or resilience to drug addiction and associated relapse. Increasing evidence suggests microglia and astrocytes can profoundly affect the physiological and addictive properties of drugs of abuse, including morphine. We report that glia within the rat nucleus accumbens (NAcc) respond to morphine with an increase in cytokine/chemokine expression, which predicts future reinstatement of morphine conditioned place preference (CPP) following a priming dose of morphine. This glial response to morphine is influenced by early-life experience. A neonatal handling paradigm that increases the quantity and quality of maternal care significantly increases baseline expression of the anti-inflammatory cytokine IL-10 within the NAcc, attenuates morphine-induced glial activation, and prevents the subsequent reinstatement of morphine CPP in adulthood. IL-10 expression within the NAcc and reinstatement of CPP are negatively correlated, suggesting a protective role for this specific cytokine against morphine-induced glial reactivity and drug-induced reinstatement of morphine CPP. Neonatal handling programs the expression of IL-10 within the NAcc early in development, and this is maintained into adulthood via decreased methylation of the IL-10 gene specifically within microglia. The effect of neonatal handling is mimicked by pharmacological modulation of glia in adulthood with ibudilast, which increases IL-10 expression, inhibits morphine-induced glial activation within the NAcc, and prevents reinstatement of morphine CPP. Taken together, we have identified a novel gene × early-life environment interaction on morphine-induced glial activation and a specific role for glial activation in drug-induced reinstatement of drug-seeking behavior.
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Affiliation(s)
- Jaclyn M Schwarz
- Department of Psychology and Neuroscience, Duke University, Durham, North Carolina 27705, USA.
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Yusko B, Hawk K, Schiml PA, Deak T, Hennessy MB. Sensitization of depressive-like behavior during repeated maternal separation is associated with more-rapid increase in core body temperature and reduced plasma cortisol levels. Physiol Behav 2011; 105:861-7. [PMID: 22079581 DOI: 10.1016/j.physbeh.2011.10.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 10/25/2011] [Accepted: 10/26/2011] [Indexed: 11/24/2022]
Abstract
Infant guinea pigs exhibit a 2-stage response to maternal separation: an initial active stage, characterized by vocalizing, and a second passive stage marked by depressive-like behavior (hunched posture, prolonged eye-closure, extensive piloerection) that appears to be mediated by proinflammatory activity. Recently we found that pups showed an enhanced (i.e., sensitized) depressive-like behavioral response during repeated separation. Further, core body temperature was higher during the beginning of a second separation compared to the first, suggesting a more-rapid stress-induced febrile response to separation the second day, though the possibility that temperature was already elevated prior to the second separation could not be ruled out. Therefore, the present study examined temperature prior to, and during, 2 daily separations. We also examined the temperature response to a third separation conducted 3 days after the second, and assessed the effect of repeated separation on plasma cortisol levels. Core temperature did not differ just prior to the separations, but showed a more-rapid increase and then decline during both a second and third separation than during a first. Temperature responses were not associated with changes in motor activity. Depressive-like behavior was greater during the second and third separations. Pups separated a first time showed a larger plasma cortisol response at the conclusion of separation than did animals of the same age separated a third time. In all, the results indicate that the sensitization of depressive-like behavior during repeated separations over several days is accompanied by a more-rapid febrile response that may be related to a reduction of glucocorticoid suppression.
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Affiliation(s)
- Brittany Yusko
- Department of Psychology, Wright State University, Dayton, OH 45435, USA
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