New Perspectives in Neurosteroids action: a Special Player Allopregnanolone


Book Description

Early in the 80’s date the first observations on the existence of hormonal steroids that may be synthesized and act in the nervous system. In order to refer to these endogenous steroids, proved important to control both central and peripheral nervous system, it was proposed the term “neurosteroids” (NSs). Over the years, their importance in regulating the physiological functions of neuronal and glial cells increased progressively. These steroids can be involved in several pathophysiological conditions such as depression, anxiety, premenstrual syndrome (PMS), schizophrenia and Alzheimer disease. Among the different classes of NSs, the progestagens revealed particularly important. The progesterone metabolite 5a-pregnan-3a-ol-20-one, also named tetrahydroprogesterone or allopregnanolone (ALLO) was one of the first most important steroid that was originally shown to act as neurosteroid. ALLO is synthesized through the action of the 5aR-3a-HSD, which converts P into DHP and subsequently, via a bidirectional reaction, into ALLO. NSs exert complex effects in the nervous system through ‘classic’, genomic, and ‘non-classic’, non-genomic actions. ALLO displays a rapid ‘non-genomic’ effect, which mainly involves the potent modulation of the GABA type A (GABA-A) receptor function. Recently a membrane receptor has been identified as target for ALLO effects, i.e. the membrane progesterone receptors (mPRs) that are able to activate a signalling cascade through G protein dependent mechanisms. By these ways, ALLO is able to modulate several cell functions, acting as neurogenic molecule on neural progenitor cells, as well as by activating proliferation and differentiation of glial cells in the central and peripheral nervous system. In this topic, we review the most recent acquisitions in the field of neurosteroids, focusing our attention on ALLO because its effects on the physiology of neurons and glial cells of the central and peripheral nervous system are intriguing and could potentially lead to the development of new strategies for neuroprotection and/or regeneration of injured nervous tissues and for the treatment of neuropsychiatric disorders.




Fluoxetine


Book Description

Fluoxetine, best known by the trade name Prozac®, unlike other psychotropic drugs whose effects were serendipitously stumbled upon, was the first developed for a precise mechanism of action, that is, the ability to selectively inhibit serotonin reuptake, based upon the theory that increasing the availability of serotonin would treat major depression. Once approved by the FDA in 1987, fluoxetine quickly became the most prescribed psychotropic drug worldwide and its success in improving mood disorders has triggered the development of a large number of congener molecules, commonly known as SSRIs after their purported mechanism of action. However, a quarter of a century after its development, the idea that fluoxetine asserts its positive behavioral effect through inhibition of serotonergic reuptake is not firmly established. This book reviews several preclinical and clinical reports suggesting that the pharmacological effects of fluoxetine may be mediated by means other than the regulation of serotonin, including the regulation of gene expression, modifying epigenetic mechanisms as well as modifying microRNAs. One of the most prominent mechanisms for the therapeutic relevance of fluoxetine relates to influencing neuroplasticity by enhancing neurotropic factors, including BDNF signaling and altering adult neurogenesis. The ability of fluoxetine to rapidly increase neurosteroid levels accounts for the fast anxiolytic effects of this drug. Fluoxetine action at sigma-1 receptor or modulating glutamatergic neurotransmission as well as the combination of fluoxetine with other psychotropic drugs is discussed in relation to its therapeutic effects. While fluoxetine was primarily prescribed as an antidepressant, this drug currently represents a treatment of choice for a broad spectrum of psychiatric disorders, including post-traumatic stress disorder and a range of anxiety disorders. This drug even possesses analgesic actions and is a valuable therapy for stroke. This book also highlights emerging evidence on the gender-specific effects of fluoxetine, its potential adverse features, including its addiction liability in combination with psychostimulants, and the impact of perinatal fluoxetine exposure.




Sex Differences in the Central Nervous System


Book Description

Sex Differences in the Central Nervous System offers a comprehensive examination of the current state of sex differences research, from both the basic science and clinical research perspectives. Given the current NIH directive that funded preclinical research must consider both females and males, this topic is of interest to an increasing percentage of the neuroscience research population. The volume serves as an invaluable resource, offering coverage of a wide range of topics: sex differences in cognition, learning, and memory, sex hormone signaling mechanisms, neuroimmune interactions, epigenetics, social behavior, neurologic disease, psychological disorders, and stress. Discussions of research in both animal models and human patient populations are included. Details how sex hormones have widespread effects on the nervous system and influence the way males and females function Assists readers in determining how sex impacts their research and practice, and assists in determining how to adjust research programs to incorporate sex influences Includes discussions of research in both animal models and human patient populations, and at various developmental stages Features revised and updated chapters by leaders in the field around the globe—the broadest, most expert coverage available




Synaptic Stress and Pathogenesis of Neuropsychiatric Disorders


Book Description

Recent studies show that changes in Glutamate/GABA synapses and related pathways may determine whether the synaptic plasticity that occurs as a response to stress is adaptive or maladaptive. Findings have shed new light on the mechanisms that determine the effects of stress on cognitive and affective function. Researchers have brought a wide range of techniques to bear on the study of this problem, including cutting-edge live imaging techniques, electrophysiology, glutamate release from isolated live synaptic terminals, development of transgenic and animal models and new behavioral methods. This book provides an overview of these recent findings and of the techniques used as well as a discussion of how the molecular, cellular, and functional effects of stress may trigger or precipitate neuropsychiatric disorders such as depression, schizophrenia, anxiety and PTSD.




Sex Hormones in Neurodegenerative Processes and Diseases


Book Description

The book provides chapters on sex hormones and their modulation in neurodegenerative processes and pathologies, from basic molecular mechanisms, physiology, gender differences, to neuroprotection and clinical aspects for potential novel pharmacotherapy approaches. The book contains 14 chapters written by authors from various biomedical professions, from basic researchers in biology and physiology to medicine and veterinary medicine, pharmacologists, psychiatrist, etc. Chapters sum up the past and current knowledge on sex hormones, representing original new insights into their role in brain functioning, mental disorders and neurodegenerative diseases. The book is written for a broad range of audience, from biomedical students to highly profiled medical specialists and biomedical researchers, helping them to expand their knowledge on sex hormones in neurodegenerative processes and opening new questions for further investigation.




Patterning and Cell Type Specification in the Developing CNS and PNS


Book Description

The genetic, molecular, and cellular mechanisms of neural development are essential for understanding evolution and disorders of neural systems. Recent advances in genetic, molecular, and cell biological methods have generated a massive increase in new information, but there is a paucity of comprehensive and up-to-date syntheses, references, and historical perspectives on this important subject. The Comprehensive Developmental Neuroscience series is designed to fill this gap, offering the most thorough coverage of this field on the market today and addressing all aspects of how the nervous system and its components develop. Particular attention is paid to the effects of abnormal development and on new psychiatric/neurological treatments being developed based on our increased understanding of developmental mechanisms. Each volume in the series consists of review style articles that average 15-20pp and feature numerous illustrations and full references. Volume 1 offers 48 high level articles devoted mainly to patterning and cell type specification in the developing central and peripheral nervous systems. - Series offers 144 articles for 2904 full color pages addressing ways in which the nervous system and its components develop - Features leading experts in various subfields as Section Editors and article Authors - All articles peer reviewed by Section Editors to ensure accuracy, thoroughness, and scholarship - Volume 1 sections include coverage of mechanisms which: control regional specification, regulate proliferation of neuronal progenitors and control differentiation and survival of specific neuronal subtypes, and controlling development of non-neural cells




New Antiepileptic Drugs


Book Description

The pharmacological fight against epilepsy began many centuries ago when Hippocrates discovered that the cause of epilepsy is natural, as opposed to supernatural and, as a consequence, must be treated with a natural remedy. Even though science has significantly progressed since that era, the challenge to find remedies for epilepsy is ever present. The aim of this particular volume is to offer an up-to-date review of the most recent advances in antiepileptic drug development, considered from various viewpoints: (i) general, by taking into account the size of refractory epilepsy and its related problems; (ii) experimental, by exploring the mechanisms of epileptogenesis and the possiblility of influencing it through drugs, and (iii) clinical, by describing the results obtained with compounds currently at an advanced stage of testing.




Neurosteroids and Brain Function


Book Description

International Review of Neurobiology, Volume 46 presents in-depth reviews on such ground-breaking topics as assembly and intracellular trafficking of GABA A receptors, D-1 dopamine receptors, and Alzheimer's disease. This series offers the most comprehensive and up-to-date information available and is a must for anyone in the field. Includes a historical overview of neurosteroid research Contains a chapter on neurosteroid biosynthesis and regulation Presents current methods of neurosteroid measurement and analysis Discusses neurosteroid function in both the normal and the pathological brain Chapters address the function of neurosteroid in: Stress, Receptor plasticity and function, Learning and Memory, Alcohol use, Depression




The Neurobiological Basis of Suicide


Book Description

With recent studies using genetic, epigenetic, and other molecular and neurochemical approaches, a new era has begun in understanding pathophysiology of suicide. Emerging evidence suggests that neurobiological factors are not only critical in providing potential risk factors but also provide a promising approach to develop more effective treatment and prevention strategies. The Neurobiological Basis of Suicide discusses the most recent findings in suicide neurobiology. Psychological, psychosocial, and cultural factors are important in determining the risk factors for suicide; however, they offer weak prediction and can be of little clinical use. Interestingly, cognitive characteristics are different among depressed suicidal and depressed nonsuicidal subjects, and could be involved in the development of suicidal behavior. The characterization of the neurobiological basis of suicide is in delineating the risk factors associated with suicide. The Neurobiological Basis of Suicide focuses on how and why these neurobiological factors are crucial in the pathogenic mechanisms of suicidal behavior and how these findings can be transformed into potential therapeutic applications.




Extrasynaptic GABAA Receptors


Book Description

GABA is the principal inhibitory neurotransmitter in the CNS and acts via GABAA and GABAB receptors. Recently, a novel form of GABAA receptor-mediated inhibition, termed “tonic” inhibition, has been described. Whereas synaptic GABAA receptors underlie classical “phasic” GABAA receptor-mediated inhibition (inhibitory postsynaptic currents), tonic GABAA receptor-mediated inhibition results from the activation of extrasynaptic receptors by low concentrations of ambient GABA. Extrasynaptic GABAA receptors are composed of receptor subunits that convey biophysical properties ideally suited to the generation of persistent inhibition and are pharmacologically and functionally distinct from their synaptic counterparts. This book highlights ongoing work examining the properties of recombinant and native extrasynaptic GABAA receptors and their preferential targeting by endogenous and clinically relevant agents. In addition, it emphasizes the important role of extrasynaptic GABAA receptors in GABAergic inhibition throughout the CNS and identifies them as a major player in both physiological and pathophysiological processes.