Physiology Of Astroglia

Astrocytes can be defined as the glia inhabiting the nervous system with the main function in the maintenance of nervous tissue homeostasis. Classified into several types according to their morphological appearance, many of astrocytes form a reticular structure known as astroglial syncytium, owing to their coupling via intercellular channels organized into gap junctions. Not only do astrocytes establish such homocellular contacts, but they also engage in intimate heterocellular interactions with neurons, most notably at synaptic sites. As synaptic structures house the very core of information transfer and processing in the nervous system, astroglial perisynaptic positioning assures that these glial cells can nourish neurons and establish bidirectional communication with them, functions outlined in the concepts of the astrocytic cradle and multi-partite synapse, respectively. Astrocytes possess a rich assortment of ligand receptors, ion and water channels, and ion and ligand transporters, which collectively contribute to astrocytic control of homeostasis and excitability. Astroglia control glutamate and adenosine homeostasis to exert modulatory actions affecting the real-time operation of synapses. Fluctuations of intracellular calcium can lead to the release of various chemical transmitters from astrocytes through a process termed gliotransmission. Sodium fluctuations are closely associated to those of calcium with both dynamic events interfacing signaling and metabolism. Astrocytes appear fully integrated into the brain cellular circuitry, being an indispensable part of neural networks.

Astrocytes were the original neuroglia that Ramón y Cajal visualized in 1913 using a gold sublimate stain. This stain targeted intermediate filaments that we now know consist mainly of glial fibrillary acidic protein, a protein used today as an astrocytic marker. Cajal described the morphological diversity of these cells with some ast- cytes surrounding neurons, while the others are intimately associated with vasculature. We start the book by discussing the heterogeneity of astrocytes using contemporary tools and by calling into question the assumption by classical neuroscience that neurons and glia are derived from distinct pools of progenitor cells. Astrocytes have long been neglected as active participants in intercellular communication and information processing in the central nervous system, in part due to their lack of electrical excitability. The follow up chapters review the “nuts and bolts” of ast- cytic physiology; astrocytes possess a diverse assortment of ion channels, neu- transmitter receptors, and transport mechanisms that enable the astrocytes to respond to many of the same signals that act on neurons. Since astrocytes can detect chemical transmitters that are released from neurons and can release their own extracellular signals there is an increasing awareness that they play physiological roles in regulating neuronal activity and synaptic transmission. In addition to these physiological roles, it is becoming increasingly recognized that astrocytes play critical roles during pathophysiological states of the nervous system; these states include gliomas, Alexander disease, and epilepsy to mention a few.

Glial Physiology and Pathophysiology provides a comprehensive, advanced text on the biology and pathology of glial cells. Coverae includes: the morphology and interrelationships between glial cells and neurones in different parts of the nervous systems the cellular physiology of the different kinds of glial cells the mechanisms of intra- and inter-cellular signalling in glial networks the mechanisms of glial-neuronal communications the role of glial cells in synaptic plasticity, neuronal survival and development of nervous system the cellular and molecular mechanisms of metabolic neuronal-glial interactions the role of glia in nervous system pathology, including pathology of glial cells and associated diseases - for example, multiple sclerosis, Alzheimer's, Alexander disease and Parkinson's Neuroglia oversee the birth and development of neurones, the establishment of interneuronal connections (the 'connectome'), the maintenance and removal of these inter-neuronal connections, writing of the nervous system components, adult neurogenesis, the energetics of nervous tissue, metabolism of neurotransmitters, regulation of ion composition of the interstitial space and many, many more homeostatic functions. This book primes the reader towards the notion that nervous tissue is not divided into more important and less important cells. The nervous tissue functions because of the coherent and concerted action of many different cell types, each contributing to an ultimate output. This reaches its zenith in humans, with the creation of thoughts, underlying acquisition of knowledge, its analysis and synthesis, and contemplating the Universe and our place in it. An up-to-date and fully referenced text on the most numerous cells in the human brain Detailed coverage of the morphology and interrelationships between glial cells and neurones in different parts of the nervous system Describes the role og glial cells in neuropathology Focus boxes highlight key points and summarise important facts Companion website with downloadable figures and slides

This book provides a comprehensive overview of the role of neuroglia in neurodegenerative diseases. Neuroglia are the most abundant cells in the nervous system and consist of several distinct cell types, such as astrocytes, oligodendrocytes,and microglia. Accumulating evidence suggests that neuroglia participate in the neurodegenerative process, and as such are essential players in a variety of diseases, including Alzheimer’s, Parkinson’s, and Huntington’s. Intended for researchers and students, the book presents recent advances concerning the biology of neuroglia as well as their interaction with neurons during disease progression. In addition, to highlight the function of neuroglia in different types of neurodegenerative disease, it also discusses their mechanisms and effects on protecting or damaging neurons.

A team of authors from prestigious academic schools contributed to draw up a project that would give a detailed account of astrocyte's morphology and physiology, examining thoroughly all the astrocyte's types; giving an accurate description of their morphology, location, function in the brain; and illustrating their physiology and pathology in terms of dealing with neurons through "gliotransmitters," ionic channels, and membrane receptors expression. This book gives an overview of the crucial role of astrocytes in the physiology of the CNS and in the pathogenesis of several CNS disorders suggesting that the shift from a neurocentric view to one that incorporates astrocytes in disease models for drug discovery is a critical step in renewing drug development strategies to treat neurodegenerative diseases.

Astrocytes: Cell Biology and Pathology of Astrocytes, Volume 3 deals with the involvement of astrocytes in neurological and neuropathological states of brain function. This volume discusses the expression of astrocyte-specific immunological markers and plasma membrane structures; the dynamics of the cytoskeleton and cell cycle; and the reactivity to injury and response of astrocytes in selected pathological and genetic states. The text also aims to inspire new ideas and research on astrocyte functions as well as on the pathogenesis of neurological disorders. Neuroscientists, cell biologists, clinicians, neuropathologists, and pediatric neurologists will find the book invaluable.

Astrocytes: Biochemistry, Physiology, and Pharmacology of Astrocytes, Volume 2 focuses on the physiological and pharmacological aspects of astrocytes. This volume gives specific attention to intracellular metabolic activity; membrane components and functions; responses to neurotransmitters and other intrinsic factors; and neuronal-glial interactions. Studies in this text establishe the astrocyte as an essential neuronal partner in the neuronal-glial interrelationship throughout the life-span of the neuron and also further explain the potential roles of astrocytes in brain function. Cell physiologists, neurophysiologists, neuropharmacologists, pediatric neurologists, and gerontologists will find the book interesting.

A timely overview covering the three major types of glial cells in the central nervous system - astrocytes, microglia, and oligodendrocytes. New findings on glia biology are overturning a century of conventional thinking about how the brain operates and are expanding our knowledge about information processing in the brain. The book will present recent research findings on the role of glial cells in both healthy function and disease. It will comprehensively cover a broad spectrum of topics while remaining compact in size.