It has been my privilege and pleasure during the past half century to participate in the unfolding of present-day concepts of the mammalian female reproductive cycles. When the studies recorded here began in the late 1930s it was already established that cyclic ovarian function is governed by gonadotropic secretions from the anterior pituitary gland, the "conductor of the endrocrine orchestra," and that in turn this activity is importantly dependent in some way upon secretion of estro gens and progesterone by the ovaries. Although a role of the nervous system was recognized for the reflex-like induction of ovulation in rabbits and cats and the in duction of pseudopregnancy in rats and mice, and although there was even some evidence of neural participation in ovulation in rats, a major central neural role in the female cycle of most species was not apparent. Gonadotropic fractions of pitui tary extracts having distinct follicle-stimulating and luteinizing activities in test ani mals had been obtained, and these respective effects had been fairly well charac terized. Prolactin was well known for its lactogenic activity, but its luteotropic role in rats and mice had yet to be revealed. The molecular structure of the several estro gens and progesterone was known, and they were readily available as synthetic pro ducts. The broad concept of ovarian-pituitary reciprocity appeared to be an accept able explanation of the female cycle, with the ovary in control through the rhythmic rise and fall in secretion of follicular estrogen.

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.

Intraspecific communication involves the activation of chemoreceptors and subsequent activation of different central areas that coordinate the responses of the entire organism—ranging from behavioral modification to modulation of hormones release. Animals emit intraspecific chemical signals, often referred to as pheromones, to advertise their presence to members of the same species and to regulate interactions aimed at establishing and regulating social and reproductive bonds. In the last two decades, scientists have developed a greater understanding of the neural processing of these chemical signals. Neurobiology of Chemical Communication explores the role of the chemical senses in mediating intraspecific communication. Providing an up-to-date outline of the most recent advances in the field, it presents data from laboratory and wild species, ranging from invertebrates to vertebrates, from insects to humans. The book examines the structure, anatomy, electrophysiology, and molecular biology of pheromones. It discusses how chemical signals work on different mammalian and non-mammalian species and includes chapters on insects, Drosophila, honey bees, amphibians, mice, tigers, and cattle. It also explores the controversial topic of human pheromones. An essential reference for students and researchers in the field of pheromones, this is also an ideal resource for those working on behavioral phenotyping of animal models and persons interested in the biology/ecology of wild and domestic species.

Female reproductive senescence is widespread among mammalian species, but menopause is limited to species with menstrual cycles. While hormonal changes at menopause have profound impacts in the lives of women at middle age, the complex mechanisms underlying this process remain obscure. All three levels of the hypothalamic-pituitary-gonadal (HPG) axis are involved in reproductive aging, and evidence highlights a critical role for the dysregulation of gonadotropin-releasing hormone (GnRH) neurons, the hypothalamic cells that drive reproductive function. To investigate neuroendocrine mechanisms that may initiate and perpetuate reproductive decline at each step in the transition to acyclicity, I utilized an ovarian-intact middle-aged female rat model of natural reproductive senescence. These studies focused on three hypothalamic nuclei that are known to control GnRH activity: the anteroventral periventricular nucleus (AVPV), the site of positive hormone feedback onto GnRH neurons; the arcuate nucleus (ARC), the site of negative feedback; and the median eminence (ME), the site of GnRH release, with the following specific aims: 1) Characterize neuroendocrine gene and protein expression in female rats throughout the natural transition to acyclicity; 2) Determine the effects of chronic N-methyl-D-asparate receptor subunit 2b (NMDAR-NR2b) inhibition in acyclic females; and 3) Examine neuroendocrine gene expression during premature reproductive senescence after perturbation of the HPG axis. The results of these studies identified novel molecular and cellular changes with age and reproductive cycle status in the ARC and ME, two regions that are underappreciated for their roles in reproductive senescence. Surprisingly, few molecular targets were identified in the AVPV, a region that is much better-studied in this context. In the ME and ARC, I found changes in transcription factors and evidence of altered hormone feedback via changes in sex steroid hormone receptors and enzyme expression with reproductive aging. I also discovered decreased expression of genes for the excitatory neuropeptides, kisspeptin and neurokinin B, as well as decreased percentage of kisspeptin immunoreactive cells and their co-expression with estrogen receptor alpha in the ARC. And finally, in the ME, neurotrophic factor expression was changed with age, and the presence and phosphorylation state of the NR2b subunit of the NMDA receptor contributes to a greater inhibitory tone with acyclicity. Together these studies have identified novel pathways, especially in the ARC and ME, that are related to reproductive decline. Furthermore, changes in the hypothalamic neural and glial network of neurotransmitters, neuropeptides, hormone receptors and other transcription factors are likely contributing to altered responses to hormonal feedback and decreased excitatory drive for GnRH release.