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​While steroids from the periphery have profound effects on the nervous system, the nervous system also produces its own steroids de novo (“neurosteroids”). The physiological importance of neurosteroids is beginning to be understood. These steroids potentially have roles in sedative/hypnotic behavior, anxiety, learning, and memory. At the cellular level, neurosteroids affect neuronal excitability, synaptic plasticity and cell proliferation and survival. Early findings hold promise for future strategies to treat specific psychologicalconditions and neurological diseases. This Brief will focus on the current state of understanding of brainderived neurosteroids.

The discovery of insect neurohormones dates from the earliest experimental in­ vestigations in insect endocrines, and the matter cannot be discussed without evoking the names of its pioneers-Kopec, Wigglesworth, Fraenkel. Whereas the experiments demonstrated the existence of the first known neurohormones, the formulation of the concept of neurosecretion was of fundamental importance to further progress, and tribute must be paid to Ernst and Berta Scharrer. The recent proliferation of investigations into insect neurohormones has cre­ ated the need for an overall review of the data. Our knowledge of the subject is voluminous, and the evidence clearly demonstrates that neurohormones playa part in most insect regulatory processes. This book analyzes and synthesizes the data, starting from neurosecretion (i.e., source sites and release modes of neurohormones) and continuing through the various functions in which neurohormones have been shown to be involved: endocrine gland activity; diapause; reproduction; visceral muscle functioning; color change; behavior; water and ion balance; protein, sugar, and lipid metabo­ lism; and tanning and other processes occurring at the cuticle level. In each chapter, besides the experimental information, technical procedures as well as recent information concerning purification of the particular neurohor­ mones and their mode of action are reported. Numerous exhaustive tables allow the reader to get an overview of the matter while the major findings of the mo­ ment are presented in the conclusion of each chapter.

The most striking fact revealed by investigations of insect neurohormones is that insects are as well supplied with neurohormones as mammals, since neurohor­ mones regulate not only the functioning of the endocrine glands, prothoracic gland, and corpora allata, but also most physiological processes. Our knowledge of neurohormones developed originally from anat­ omocytological investigations and experimental studies. Today, accurate bio­ assays have been devised for studying both in vivo and in vitro physiological processes, and RIA determination has yielded knowledge of titer modifications of humoral factors. Much is also known about neurohormone purification, and several neurohormones have even been identified in different species. Immunocytochemistry has made it possible to demonstrate in their origin and release sites the presence of insect neurohormones whose structure has been elucidated. Moreover, the presence of vertebrate and invertebrate neuropeptides has been demonstrated in insects. As regards biogenic amines, methods of detection have been greatly refined and it is now possible to identify the cell bodies and axons of the main biogenic amines. Other new methods, such as cobalt chloride impregnation or Lucifer yellow staining, have revealed the axonal pathways and the location of particular neurons. The mechanisms of action of neurohormones have been investigated in several cases and the results of these investigations will be related in the chapters which follow.

As life expectancy increases and population ages, the already enormous impact of neurodegeneration on society will become even larger without better prevention and treatment. Developing strategies to prevent degeneration of neurons and to promote a healthy nervous system is, thus, critical. The development of pharmacological agents that would increase production of new neurons was recently facilitated by the identification of the hormonal regulators of various steps of adult neurogenesis. The proposed book is writen by a group of top world experts involved in the study of the mechanisms of hormonal control of brain damage and repair. The effects of thyroid and steroid hormones (estrogens, androgens, progestins, gluco-mineralo-corticoids, various neurosteroids) or polypeptide hormones (CRF, urocortins, somatostastin, GH/IGF, leptin, prolactin, PACAP, erythropoetin) on neuronal survival and neurogenesis in various neurodegenerative conditions and in brain aging will be discussed in detail. The proposed book is unique because it gives a comprehensive account of the neuroprotective and neurogenic effects of steroid and polypeptide hormones. Furthermore, new pharmacological approaches for treatment of neurodegenerative conditions are presented, based on the neuroprotective and neurogenic properties of natural and synthetic hormones.

Over the past few decades the involvement of neurosteroids in brain function and mental health has attracted much interest, not only from a neuroscience perspective, but also from clinical and therapeutic aspects. In recent years, much of the research has focused on the multifunctional position of neurosteroids in the nervous system. The areas that have been explored, in particular, are the cellular and molecular mechanisms involved in the activity of neurosteroids in the brain, the role of neurosteroids in brain development, neurodegeneration and neuroplasticity, and their pharmacological properties. The large increase in the number of publications highlights this amplified interest in neurosteroids. Over the last 7 years at least 400 papers have been published describing the putative role of neurosteroids in the modulation of basic brain function and in the etiology and treatment of psychiatric and neurological disorders. Contributors to this book are amongst the most active basic researchers and c- nicians in the field and provide new perspectives not only clarifying some of the ongoing controversies, but also proposing diverse aspects and new insights. The book is organized in two major sections: “Neuroactive steroids and brain function', and ‘Neuroactive steroids and neuropsychiatric disorders”. Though the selection of topics has been influenced by the current state of the art and the issues that require further elaboration, one should not assume that these are the only significant issues at this time.

Advances in Brain Vasopressin elucidates the functions of the regulatory peptide vasopressin in the nervous system, and reviews the current status of this field at different levels. It deals with the cell biology and anatomy of the neurons that produce vasopressin in the brain, and provides an overview on the receptors of vasopressin and the signal transduction pathways that they activate, including the cellular responses that are triggered by vasopressin. Reviews are presented on the modulation of behavior induced by vasopressin in a number of different contexts, such as sex-linked and steroid-dependent behaviors, social behaviors, and learning and memory. Furthermore, the volume deals with several controversial issues in the field by presenting overlapping chapters from different research groups in order to provide the reader with current views. Highly relevant and useful, for those working on this'first'neuropeptide, and for young investigators entering the field, and in addition, shows how important a multidisciplinary approach is to unravelling the function of a neuropeptide in the brain.