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Schubert I, Ahlbrand R, Winter A, Vollmer L, Lewkowich I, Sah R. Enhanced fear and altered neuronal activation in forebrain limbic regions of CX3CR1-deficient mice. Brain Behav Immun 2018; 68:34-43. [PMID: 28943292 PMCID: PMC8411798 DOI: 10.1016/j.bbi.2017.09.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 09/03/2017] [Accepted: 09/21/2017] [Indexed: 12/27/2022] Open
Abstract
Mounting evidence supports immune dysfunction in psychiatric conditions such as post-traumatic stress disorder (PTSD). The association of immunomodulatory mechanisms with PTSD-relevant behavior and physiology is not well understood. Communication between neurons and microglia, resident immune cells of the central nervous system, is crucial for optimal regulation of behavior and physiology. In this regard, the fractalkine CX3CL1, secreted from neurons and its target, the microglial CX3CR1 receptor represent a primary neuron-microglia inter-regulatory system important for synaptic plasticity and function. The current study investigated the impact of CX3CR1 deficiency on behaviors relevant to PTSD, such as fear acquisition and memory, acoustic startle response and anxiety-like behavior. Morphological analysis of microglia and neuronal activation within PTSD-relevant forebrain nuclei regulating stress and fear behaviors was also conducted. CX3CR1-deficient (CX3CR1-/-) mice elicited increased fear acquisition as well as reinstatement of fear as compared to wild type (CX3CR1+/+) mice. Conditioned fear and extinction were not significantly different between genotypes. No significant differences were observed in unconditioned acoustic startle response between genotypes. CX3CR1-/- mice showed reduced anxiety-like behaviors as compared with CX3CR1+/+ mice. Morphological assessment of microglia showed region-selective effects of CX3CR1 deficiency, primarily within hypothalamic and cortical areas. Lastly, CX3CR1-/- mice elicited elevated neuronal activity in the PVN and the ventral tegmental-interpeduncular area following reinstatement of fear. Collectively, our data suggest that impaired CX3CR1 function may evoke region-selective alterations in forebrain circuits regulating stress, anxiety and fear, impacting behaviors relevant to disorders such as PTSD.
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Affiliation(s)
- Inga Schubert
- Dept. of Psychiatry and Behavioral Neuroscience, University of Cincinnati, United States; Neuroscience Undergraduate Program, University of Cincinnati, United States
| | - Rebecca Ahlbrand
- Dept. of Psychiatry and Behavioral Neuroscience, University of Cincinnati, United States
| | - Andrew Winter
- Dept. of Psychiatry and Behavioral Neuroscience, University of Cincinnati, United States; Neuroscience Graduate Program, University of Cincinnati, Cincinnati, OH 45237, United States
| | - Lauren Vollmer
- Dept. of Psychiatry and Behavioral Neuroscience, University of Cincinnati, United States
| | - Ian Lewkowich
- Dept. of Immunobiology, Children's Hospital Medical Center, Cincinnati, United States
| | - Renu Sah
- Dept. of Psychiatry and Behavioral Neuroscience, University of Cincinnati, United States; Neuroscience Graduate Program, University of Cincinnati, Cincinnati, OH 45237, United States; VA Medical Center, Cincinnati, OH 45220, United States.
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Tay TL, Béchade C, D'Andrea I, St-Pierre MK, Henry MS, Roumier A, Tremblay ME. Microglia Gone Rogue: Impacts on Psychiatric Disorders across the Lifespan. Front Mol Neurosci 2018; 10:421. [PMID: 29354029 PMCID: PMC5758507 DOI: 10.3389/fnmol.2017.00421] [Citation(s) in RCA: 138] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 12/04/2017] [Indexed: 12/21/2022] Open
Abstract
Microglia are the predominant immune response cells and professional phagocytes of the central nervous system (CNS) that have been shown to be important for brain development and homeostasis. These cells present a broad spectrum of phenotypes across stages of the lifespan and especially in CNS diseases. Their prevalence in all neurological pathologies makes it pertinent to reexamine their distinct roles during steady-state and disease conditions. A major question in the field is determining whether the clustering and phenotypical transformation of microglial cells are leading causes of pathogenesis, or potentially neuroprotective responses to the onset of disease. The recent explosive growth in our understanding of the origin and homeostasis of microglia, uncovering their roles in shaping of the neural circuitry and synaptic plasticity, allows us to discuss their emerging functions in the contexts of cognitive control and psychiatric disorders. The distinct mesodermal origin and genetic signature of microglia in contrast to other neuroglial cells also make them an interesting target for the development of therapeutics. Here, we review the physiological roles of microglia, their contribution to the effects of environmental risk factors (e.g., maternal infection, early-life stress, dietary imbalance), and their impact on psychiatric disorders initiated during development (e.g., Nasu-Hakola disease (NHD), hereditary diffuse leukoencephaly with spheroids, Rett syndrome, autism spectrum disorders (ASDs), and obsessive-compulsive disorder (OCD)) or adulthood (e.g., alcohol and drug abuse, major depressive disorder (MDD), bipolar disorder (BD), schizophrenia, eating disorders and sleep disorders). Furthermore, we discuss the changes in microglial functions in the context of cognitive aging, and review their implication in neurodegenerative diseases of the aged adult (e.g., Alzheimer’s and Parkinson’s). Taking into account the recent identification of microglia-specific markers, and the availability of compounds that target these cells selectively in vivo, we consider the prospect of disease intervention via the microglial route.
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Affiliation(s)
- Tuan Leng Tay
- Institute of Neuropathology, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Catherine Béchade
- INSERM UMR-S 839, Paris, France.,Sorbonne Universités, Université Pierre et Marie Curie (UPMC), Paris, France.,Institut du Fer à Moulin, Paris, France
| | - Ivana D'Andrea
- INSERM UMR-S 839, Paris, France.,Sorbonne Universités, Université Pierre et Marie Curie (UPMC), Paris, France.,Institut du Fer à Moulin, Paris, France
| | | | - Mathilde S Henry
- Axe Neurosciences, CRCHU de Québec-Université Laval, Québec, QC, Canada
| | - Anne Roumier
- INSERM UMR-S 839, Paris, France.,Sorbonne Universités, Université Pierre et Marie Curie (UPMC), Paris, France.,Institut du Fer à Moulin, Paris, France
| | - Marie-Eve Tremblay
- Axe Neurosciences, CRCHU de Québec-Université Laval, Québec, QC, Canada.,Département de Médecine Moléculaire, Université Laval, Québec, QC, Canada
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Vasic V, Schmidt MHH. Resilience and Vulnerability to Pain and Inflammation in the Hippocampus. Int J Mol Sci 2017; 18:ijms18040739. [PMID: 28362320 PMCID: PMC5412324 DOI: 10.3390/ijms18040739] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 03/17/2017] [Accepted: 03/27/2017] [Indexed: 02/07/2023] Open
Abstract
Increasing evidence demonstrates the importance of hippocampal neurogenesis, a fundamental mechanism of neuroplasticity associated with cognition and emotion, in correlation to neurodegenerative and psychiatric disorders. Neuropsychiatric disorders are often a result of chronic stress or pain followed by inflammation; all these conditions manifest cognitive deficits and impairments in neurogenesis. However, while some individuals are more susceptible to stress, others are able to adapt to new environments via mechanisms of resilience. In light of this emerging field and based on extensive research, the role of neurogenesis is summarized and presented as a potentially powerful therapeutic tool.
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Affiliation(s)
- Verica Vasic
- Molecular Signal Transduction Laboratories, Institute for Microscopic Anatomy and Neurobiology, Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn²), Johannes Gutenberg University, School of Medicine, Mainz 55131, Germany.
| | - Mirko H H Schmidt
- Molecular Signal Transduction Laboratories, Institute for Microscopic Anatomy and Neurobiology, Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn²), Johannes Gutenberg University, School of Medicine, Mainz 55131, Germany.
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