Reproductive processes in mammals consist of a series of physiological events: spermatogenesis, follicular growth, ovulation, progestational stage, gestation, parturition and postpartum nurturing, including lactation. In order for offspring to be reproduced effectively, these processes must proceed in the proper chronological order. In this regard, the brain, pituitary gland and gonads make up a dynamic axis in which the brain holds first place. Reproductive behaviors corresponding to each physiological event, such as copulatory and maternal behaviors, must be synchronously expressed for successful reproduction. These behaviors are considered to be the expression of higher brain function, but the expression is strictly regulated by various components of the axis. By focusing on neural activities, this book improves understanding of the physiological processes and behaviors involved in reproduction.

Gonadotropin-releasing hormone (GnRH) cells are the key regulators of reproductive function in all vertebrate organisms. The GnRH molecule is synthesized in a small number of neurons in rostral hypothalamic regions of the brain. In mammals, these neurons release the GnRH decapeptide into the portal capillary system leading to the anterior pituitary gland. There, GnRH causes the release of the gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which in turn act upon the gonads to stimulate their maturation, and to cause synthesis of sex steroid hormones, estrogen, progesterone and testosterone. Although each of the levels of the hypothalamic-pituitary-gonadal axis is critical for reproductive function, GnRH neurons play the primary role in the control of reproductive maturation and adult reproductive function, and may even play a role in reproductive senescence. Since its discovery in 1970, there has been intense interest in GnRH-producing neurons, with more than 8000 papers and chapters in the last decade alone. Despite this activity of research in basic and clinical science, there has never been a book written specifically on GnRH neurons. GnRH: The Master Molecule of Reproduction aims to bring together the large and diverse literature of both laboratory and applied research that focuses on these unique cells. This book will provide basic background into reproductive neuroendocrinology, as well as specifics regarding the role of GnRH neurons in the control of reproduction. Students studying endocrinology, reproduction, neuroendocrinology or molecular endocrinology will benefit from this book. In addition, this book will take a multi-species approach which will be useful both to basic researchers as well as clinicians. Whenever possible, species differences and similarities will be presented, and if possible, studies on humans, or the clinical relevance of basic research findings to humans will be discussed (such as the treatment of reproductive disorders such as abnormalities in pubertal development, or infertility).

This book brings together some of the results and ideas produced by a large number of people-colleagues and students with whom I am privileged to work in the laboratory at Rockefeller University. In terms of my personal history I see it as a confluence of creative forces persons from whom I have learned. I was instructed in neuroanatomy by Walle J. H. Nauta at M. I. T. , and later in a course at Harvard Medical School under the direction of Richard Sidman. At Harvard Medical School, where M. I. T. graduate students were allowed to cross register, the superb neurophysiology course was under the guiding spirit of Stephen Kuffler. Later, I benefited greatly from participating in his summer course in electrophysiological techniques at Woods Hole. Eric Kandel and his colleagues have provided us with the most exciting contemporary approach to the conceptualization and study of cellular mechanisms for behavior. Here at Rockefeller, Carl Pfaffmann and Neal Miller have been leaders in every sense of the word. Not only did they provide me with opportunities to grow to scientific maturity; they also set an example of clear thinking about mechanisms for mammalian behavior patterns. I wrote this book to show how the systematic use of increasingly detailed electrophysiological, neuroanatomical, and neuroendocrine tech niques can explain the mechanism for a mammalian behavioral response. The behavior in question happens to be sensitive to steroid hormones and plays a central role in reproduction.

The subject of this book is neuroendocrinology, that branch of biological science devoted to the interactions between the two major integrative organ systems of animals-the endocrine and nervous systems. Although this science today reflects a fusion of endocrinology and neurobiology, this synthetic ap proach is relatively recent. At the beginning of the 20th century, when the British physiologists, Bayliss and Starling, first proposed endocrinology to be an independent field of inquiry, they went to great lengths to establish the autonomy of chemical secretions in general and their independence from nervous control in particular (Bayliss, W. M. , and Starling, E. H. , 1902, The mechanism of pancreatic secretion,]. Physiol. 28:325). They argued with Pav lov, who said that there was a strong influence of the nervous system on the gastrointestinal phenomena the endocrinologists were studying. For several decades, the English physiologists prevailed, at least in the West; and Pavlov's critique was not taken to heart by the practitioners of the newly emerging discipline of endocrinology. Through the work of Harris, the Scharrers, Sawyer, Everett, and others, there has been something of a scientific detente in the latter half of this century; the hybrid field of neuroendocrinology is now regarded as one of the corner stones of modern neural science and is of fundamental importance in basic and clinical endocrinology.

A concise and innovative account of clinical neuroendocrine disorders and the key principles underlying their diagnosis and management.