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Glial Plasticity in Depression

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889199990 Year: Pages: 99 DOI: 10.3389/978-2-88919-999-0 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Neurology
Added to DOAB on : 2016-01-19 14:05:46
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Major depression is a highly prevalent disorder that poses a significant social burden in society nowadays. The pathophysiology of this disease is still poorly understood but growing evidence suggests that impaired neuron and glial plasticity may be a key underlying mechanism for the precipitation of the disorder. One of the most surprising findings in this field was the involvement of glial cells in the pathophysiology of major depression and in the action of antidepressants, namely in mechanisms related with adult neurogenesis imbalances or dendritic arborization impairments. In particular, several works refer to alterations in the morphology and numbers of astrocytes, microglia and oligodendrocytes in the context of depression in human patients or animal models of depression. These observations were linked to functional evidences and suggested to underlie the pathophysiology of depression. Among others, these include impairments in the cross-talk between glia and neurons, changes in the level of neurotransmitter or immunoactive substances, myelination status, synapse formation, maintenance, or elimination. In addition to the implication of glia in the pathophysiology of depression, a number of studies is ascribing glia pathways to classically accepted antidepressant mechanisms. Therefore, it is noteworthy to elucidate the role of glia in the effect provided by antidepressant treatment in order to better understand secondary effects and elucidate alternative targets for treatment.

Dual role of microglia in health and disease: pushing the balance towards repair

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889194926 Year: Pages: 101 DOI: 10.3389/978-2-88919-492-6 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Neurology
Added to DOAB on : 2015-11-16 15:44:59
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Microglial cells play a vital role in the innate immune response occurring in the Central Nervous System (CNS). Under physiologic conditions, microglia dynamically patrol the brain parenchyma and participate in the remodeling of active neuronal circuits. Accordingly, microglia can boost synaptic plasticity by removing apoptotic cells and by phagocytizing axon terminals and dendritic spines that form inappropriate neural connections. Upon brain and spinal cord injury or infection, microglia act as the first line of immune defense by promoting the clearance of damaged cells or infectious agents and by releasing neurotrophins and/ or proneurogenic factors that support neuronal survival and regeneration.Recently, two main pathways were suggested for microglia activation upon stimuli. Classical activation is induced by Toll-like receptor agonists and Th1 cytokines and polarizes cells to an M1 state, mainly leading to the release of TNF-alpha, IL-6 and nitric oxide and to grave neural damage. Alternative activation is mediated by Th2 cytokines and polarizes cells to an M2a state inducing the release of antiinflammatory factors. These findings have further fueled the discussion on whether microglia has a detrimental or beneficial action (M1 or M2-associated phenotypes, respectively) in the diseased or injured CNS and, more importantly, on whether we can shift the balance to a positive outcome.Although microglia and macrophages share several common features, upon M1 and M2 polarizing conditions, they are believed to develop distinct phenotypic and functional properties which translate into different patterns of activity. Moreover, microglia/macrophages seem to have developed a tightly organized system of maintenance of CNS homeostasis, since cells found in different structures have different morphology and specific function (e.g. meningeal macrophages, perivascular macrophages, choroid plexus macrophages). Nevertheless, though substantial work has been devoted to microglia function, consensus around their exact origin, their role during development, as well as the exact nature of their interaction with other cells of the CNS has not been met.This issue discusses how microglial cells sustain neuronal activity and plasticity in the healthy CNS as well as the cellular and molecular mechanisms developed by microglia in response to injury and disease. Understanding the mechanisms involved in microglia actions will enforce the development of new strategies to promote an efficient CNS repair by committing microglia towards neuronal survival and regeneration.

Single Membrane Channels Formed by Connexins or Pannexins: Focus on the Nervous System

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889198900 Year: Pages: 241 DOI: 10.3389/978-2-88919-890-0 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Neurology
Added to DOAB on : 2016-01-19 14:05:46
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Given that the extremely elaborated and dynamic functions performed by the nervous system require the close synchronization of brain cells, complex organisms have developed different mechanisms of intercellular communication. At this regard, paracrine signaling between neighboring cells is currently recognized as one of the most widely distributed mechanisms of synchronization in the brain parenchyma. In mammals, paracrine signaling is in part mediated by single membrane channels formed by connexins (connexons/hemichannels) or pannexins (pannexons), which are two different membrane protein families composed of about 20 and 3 members, respectively. Single membrane channels formed by these proteins serve as aqueous pores permeable to ions and small molecules, allowing the diffusional exchange between the intra- and extracellular milieu. Thus, connexin hemichannels and pannexons permit the release of significant quantities of autocrine/paracrine signaling molecules (e.g., ATP, glutamate, NAD+, adenosine and PGE2) into the extracellular milieu, as well as the uptake of small molecules. An increasing body of evidence has revealed that connexin hemichannels and pannexons play a crucial role in a plethora of brain processes including blood flow regulation, Ca2+ wave propagation, memory consolidation, glucose sensing and cell migration and adhesion. Considering the multiple cell signaling functions of these channels, their dysregulation is proposed not only as potential pathological biomarker, but it has been implicated in the pathogenesis and progression of diverse brain diseases (e.g., meningitis, Alzheimer’s disease and stroke). The aim of this Research Topic is to gather a collection of original research articles, method, protocols, short communications, opinions, perspectives, as well as review articles, providing the latest progress and insights in the field of connexin hemichannels and pannexons in the nervous system. Within this volume we plan to cover from basic research including channel structure, regulation, pharmacology and trafficking; to different biological functions in the physiology (behavior, plasticity, neurogenesis, blood flow control, neuron-glia crosstalk, cell migration and differentiation) as well as in the pathophysiology (neuroinflammation, mutation-related diseases, glial dysfunction and neurodegeneration) of the nervous system. We hope that this collection of articles will serve to understand how the signaling of connexin hemichannels and pannexons influences both normal and pathological brain function.

Keywords

astrocyte --- Microglia --- Neuron --- Brain --- glia --- connexin --- pannexin --- hemichannel --- connexon --- pannexon

Neuronal and glial structural plasticity induced by drugs of abuse

Authors: ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889195985 Year: Pages: 90 DOI: 10.3389/978-2-88919-598-5 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Therapeutics
Added to DOAB on : 2016-03-10 08:14:32
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Drugs of abuse induce a host of alterations in brain structure and function, ranging from changes in gene expression and epigenetic processes to aberrant synaptic plasticity to volumetric changes in discrete brain regions. These alterations can be drug class-specific, and are not confined to neurons, as drugs of abuse also induce molecular and cellular alterations in various glial cell types such as astrocytes and microglia. The phenomenon of drug-induced plasticity includes changes in dendritic branching and architecture, dendritic spine density and morphology, astrocyte-neuronal interactions, dysregulation of glutamatergic and GABAergic signaling, and alterations in myelination or microglial phenotype. This drug-induced "rewiring" of the brain at numerous levels can contribute to the development, maintenance, and persistence of the addicted state, as well as associated deficits in normal cognitive functioning. The aim of this Research Topic is to collect recent and important findings related to the structural alterations produced by drug of abuse in neurons, glial, and other cell types of the central nervous system.

Keywords

plasticity --- Dendrite --- Spine --- Glutamate --- Dopamine --- GABA --- Neuron --- glia --- astrocyte --- Addiction

Synaptic Assembly and Neural Circuit Development

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889456307 Year: Pages: 191 DOI: 10.3389/978-2-88945-630-7 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Neurology
Added to DOAB on : 2019-01-23 14:53:43
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Synapses are fundamental signaling units of the central nervous system that mediate communication between individual neurons, participate in the computation of neuronal networks, and process information through long-term modification of their strength and structure. The normal function of the central nervous system critically depends on the establishment of ‘precise’ synaptic connections between neurons and specific target cells. During synaptogenesis, synapses form, mature, stabilize, and are eliminated through processes that require intimate communication between pre- and postsynaptic partners. The sequential and/or parallel processes dictate the wiring of neural circuits in a rapid and dynamic fashion. Accumulating evidence suggests that activity-dependent synaptic and circuit plasticity reflects the assembly and disassembly of diverse synapses that occur in a distinctive manner in specific neuron types.In this Research Topic, our purpose is to compile the latest developments in our understanding of molecular and cellular mechanisms underlying pre- and postsynaptic assembly, specification of synaptic adhesion pathways, presynaptic neurotransmitter release and postsynaptic receptor trafficking. In addition, non-neuronal cell processes involved in dismantling and eliminating synapses and relevant neural circuits will be covered. Clinical implications of this research topic will be considered, emphasizing the importance of these basic neuroscience research activities for translational and therapeutic applications. This includes literature describing recent methodologies for probing key issues regarding assembly/disassembly of synapses and circuits as well as primary research articles that provide critical insights into these fundamental questions in various model systems and experimental preparations.

Cellular and molecular mechanisms of motor neuron death in amyotrophic lateral sclerosis

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889193769 Year: Pages: 190 DOI: 10.3389/978-2-88919-376-9 Language: English
Publisher: Frontiers Media SA
Subject: Neurology --- Science (General)
Added to DOAB on : 2015-11-19 16:29:12
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Amyotrophic lateral sclerosis (ALS), which was described since 1869 by Jean Martin Charcot, is a devastating neurodegenerative disease characterized by the selective and progressive loss of upper and lower motor neurons of the cerebral cortex, brainstem and the spinal cord. The cognitive process is not affected and is not merely the result of aging because may occur at young ages. The only known cause of the disease is associated with genetic mutations, mainly in the gene encoding superoxide dismutase 1 (familial ALS), whereas there is no known cause of the sporadic form of ALS (SALS), which comprises >90% of cases. Both ALS types develop similar histopathological and clinical characteristics, and there is no treatment or prevention of the disease. Because effective treatments for ALS, as for other neurodegenerative diseases, can only result from the knowledge of their cellular and molecular pathophysiological mechanisms, research on such mechanisms is essential. Although progress in neurochemical, physiological and clinical investigations in the last decades has identified several mechanisms that seem to be involved in the cell death process, such as glutamate-mediated excitotoxicity, alterations of inhibitory circuits, inflammatory events, axonal transport deficits, oxidative stress, mitochondrial dysfunction and energy failure, the understanding of the origin and temporal progress of the disease is still incomplete and insufficient. Clearly, there is a need of further experimental models and approaches to discern the importance of such mechanisms and to discover the factors that determine the selective death of motor neurons characteristic of ALS, in contrast to other neurodegenerative diseases such as Parkinson’s and Alzheimer’s disease. Whereas studies in vitro in cell cultures, tissue slices or organotypic preparations can give useful information regarding cellular and molecular mechanisms, the experiments in living animal models obviously reflect more closely the situation in the human disease, provided that the symptoms and their development during time mimics as close as possible those of the human disease. It is necessary to correlate the experimental findings in vitro with those in vivo, as well as those obtained in genetic models with those in non-genetic models, aiming at designing and testing therapeutic strategies based on the results obtained.

Advances in Neuroimmunology

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ISBN: 9783038425700 9783038425717 Year: Pages: X, 150 DOI: 10.3390/books978-3-03842-571-7 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Biology
Added to DOAB on : 2017-12-06 12:41:40
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Neuroimmunity is a relative new and rapidly expanding area of interest that critically impacts normal brain function and a wide range of neurological disorders. Neuroimmune mechanisms operate within the nervous system and between the nervous system and periphery. Glial cells of the nervous system play a primary role in neuroimmunity, through their ability to produce and respond to neuroimmune signaling factors, which serve a number of functions, such as homeostatic regulation of nervous system function and defense against insult and infection. Dysfunction of the neuroimmune system is now thought to be an important contributing factor to many disease and injury states.The purpose of this Special Issue is to provide a representative view of current research in this growing field, with an emphasis on the central nervous system.

Imaging and monitoring astrocytes in health and disease

Authors: ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889193936 Year: Pages: 189 DOI: 10.3389/978-2-88919-393-6 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Neurology
Added to DOAB on : 2015-12-03 13:02:24
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Astrocytes are key cellular partners to neurons in the brain. They play an important role in multiple processes such as neurotransmitter recycling, trophic support, antioxidant defense, ionic homeostasis, inflammatory modulation, neurovascular and neurometabolic coupling, neurogenesis, synapse formation and synaptic plasticity. In addition to their crucial involvement in normal brain physiology, it is well known that astrocytes adopt a reactive phenotype under most acute and chronic pathological conditions such as ischemia, trauma, brain cancer, epilepsy, demyelinating and neurodegenerative diseases. However, the functional impact of astrocyte reactivity is still unclear. During the last decades, the development of innovative approaches to study astrocytes has significantly improved our understanding of their prominent role in brain function and their contribution to disease states. In particular, new genetic tools, molecular probes, and imaging techniques that achieve high spatial and temporal resolution have revealed new insight into astrocyte functions in situ. This Research Topic provides a collection of cutting-edge techniques, approaches and models to study astrocytes in health and disease. It also suggests new directions to achieve discoveries on these fascinating cells.

Why and how is the self related to the brain midline regions?

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889192656 Year: Pages: 207 DOI: 10.3389/978-2-88919-265-6 Language: English
Publisher: Frontiers Media SA
Subject: Neurology --- Science (General)
Added to DOAB on : 2015-12-03 13:02:24
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What the self is and where it comes from has been one of the great problems of philosophy for thousands of years. As science and medicine have progressed this question has moved to also become a central one in psychology, psychiatry, and neuroscience. The advent of in vivo brain imaging has now allowed the scientific investigation of the self to progress further than ever. Many such imaging studies have indicated that brain structures along the cortical midline are particularly closely related to self-specific processing. This association between cortical midline structures (CMS) and self is reinforced by the involvement of these regions in other self-oriented processes, such as mind-wandering or stimulus valuation. Those midline regions involved in self- processing also overlap with another network, the default mode network, which shows high brain activity during the so-called resting state, indicating that there may be a special relationship between self-processing and intrinsic activity. Although such promising groundwork linking the self and CMS has been carried out, many questions remain. These include: what features of the midline regions lead to their apparent importance in self-processing? How can we appropriately account for confounding factors such as familiarity or task-effects in our experiments? How is the self-related to other features of the mind, such as consciousness? How is our methodology influencing our attempts to link the self and the brain? The purpose of this ebook is to address some of these questions, including opinions, perspectives, and hypotheses about the concept of the self, the relationship between CMS and the self, and the specific function of these brain regions in self-processing. It also includes original research papers describing EEG, fMRI, and behavioral experiments investigating different aspects of the self.

Transcellular Cycles Underlying Neurotransmission

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889196548 Year: Pages: 105 DOI: 10.3389/978-2-88919-654-8 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Neurology
Added to DOAB on : 2016-08-16 10:34:25
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Synaptic transmission demands the operation of a highly specialized metabolic machinery involving the transfer of metabolites and neurotransmitters between neurons, astrocytes and microvessels. In the last years, important advances have occurred in our understanding of the mechanisms underlying cerebral activation, neuroglial coupling and the associated neurovascular response. Briefly, exacerbated oxygen consumption in stimulated neurons is thought to trigger glycolytic lactate and glucose transfer from astrocytes which, in turn, obtain these fuels from the microvasculature. Neurotransmitter release is made possible by a combination of transcellular cycles exchanging metabolites between these three compartments, returning eventually the synapsis to its pre-firing situation in the resting periods. In spite of the enormous progresses achieved in recent years, the drivers determining the predominant direction of the fluxes, their quantitative contribution and their energy requirements, have remained until today incompletely understood, more particularly under the circumstances prevailing in vivo. In many instances, progress derived from the implementation of novel methodological approaches including advanced neuroimaging and neurospectroscopy methods. As a consequence, literature in the field became vast, diverse and spread within journals of different specialities. The e-book "Transcellular cycles underlying neurotransmission" aims to summaryze in a single volume, recent progress achieved in hypothesis, methods and interpretations on the trafficking of metabolites between neurons and glial cells, and the associated mechanisms of neurovascular coupling.

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