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Behavioral Neuroendocrinology

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Michael C Moore – One of the best experts on this subject based on the ideXlab platform.

  • historical contributions of research on reptiles to Behavioral Neuroendocrinology
    Hormones and Behavior, 2005
    Co-Authors: David Crews, Michael C Moore

    Abstract:

    Abstract Some of the first experiments in Behavioral endocrinology in the 1930s were conducted with lizards, but events led to a hiatus that lasted for 30 years. In the 1960s, research resumed using techniques current at the time, but it was not until the mid-1970s that Behavioral Neuroendocrinology “discovered” reptiles as animal model systems. This historical review summarizes this period of work, illustrating an enormous increase in research that have led to conclusions such as (1) the phenomenon of dissociated reproductive strategies and hormone-independent behaviors, which have aided our understanding of how the “memory” of sex steroid actions is maintained. (2) Progesterone plays an important role in the organization and activation of sexual behavior in males. Progesterone also synergizes with T to control male courtship much as does estrogen and progesterone to control sexual receptivity in females. Thus, progesterone is as much a “male” hormone as it is a “female” hormone. (3) Use of cytochrome oxidase histochemistry to study the role of experience over the long term in modifying brain activity. (4) Hormone manipulations as a powerful tool to test hypotheses about the evolution of behavior in free-living animals.

David Crews – One of the best experts on this subject based on the ideXlab platform.

  • epigenetics and its implications for Behavioral Neuroendocrinology
    Frontiers in Neuroendocrinology, 2008
    Co-Authors: David Crews

    Abstract:

    Individuals vary in their sociosexual behaviors and reactivity. How the organism interacts with the environment to produce this variation has been a focus in psychology since its inception as a scientific discipline. There is now no question that cumulative experiences throughout life history interact with genetic predispositions to shape the individual’s behavior. Recent evidence suggests that events in past generations may also influence how an individual responds to events in their own life history. Epigenetics is the study of how the environment can affect the genome of the individual during its development as well as the development of its descendants, all without changing the DNA sequence. Several distinctions must be made if this research is to become a staple in Behavioral Neuroendocrinology. The first distinction concerns perspective, and the need to distinguish and appreciate, the differences between Molecular versus Molar epigenetics. Each has its own lineage of investigation, yet both appear to be unaware of one another. Second, it is important to distinguish the difference between Context-Dependent versus Germline-Dependent epigenetic modifications. In essence the difference is one of the mechanism of heritability or transmission within, as apposed to across, generations. This review illustrates these distinctions while describing several rodent models that have shown particular promise for unraveling the contribution of genetics and the environment on sociosexual behavior. The first focuses on genetically-modified mice and makes the point that the early litter environment alters subsequent brain activity and behavior. This work emphasizes the need to understand Behavioral development when doing research with such animals. The second focuses on a new rat model in which the epigenome is permanently imprinted, an effect that crosses generations to impact the descendants without further exposure to the precipitating agent. This work raises the question of how events in generations past can have consequences at both the mechanistic, Behavioral, and ultimately evolutionary levels.

  • historical contributions of research on reptiles to Behavioral Neuroendocrinology
    Hormones and Behavior, 2005
    Co-Authors: David Crews, Michael C Moore

    Abstract:

    Abstract Some of the first experiments in Behavioral endocrinology in the 1930s were conducted with lizards, but events led to a hiatus that lasted for 30 years. In the 1960s, research resumed using techniques current at the time, but it was not until the mid-1970s that Behavioral Neuroendocrinology “discovered” reptiles as animal model systems. This historical review summarizes this period of work, illustrating an enormous increase in research that have led to conclusions such as (1) the phenomenon of dissociated reproductive strategies and hormone-independent behaviors, which have aided our understanding of how the “memory” of sex steroid actions is maintained. (2) Progesterone plays an important role in the organization and activation of sexual behavior in males. Progesterone also synergizes with T to control male courtship much as does estrogen and progesterone to control sexual receptivity in females. Thus, progesterone is as much a “male” hormone as it is a “female” hormone. (3) Use of cytochrome oxidase histochemistry to study the role of experience over the long term in modifying brain activity. (4) Hormone manipulations as a powerful tool to test hypotheses about the evolution of behavior in free-living animals.

  • The development of phenotypic plasticity: where biology and psychology meet.
    Developmental Psychobiology, 2003
    Co-Authors: David Crews

    Abstract:

    ‘‘The mechanisms that underlie much of Behavioral evolution may reside in the processes studied by developmental psychobiologists . . . ’’ Michel & Moore, 1995, p. 178. The counterpart in biology of developmental psychobiology is phenotypic plasticity, or the process by which the internal milieu and the environment induce different phenotypes from a given genotype (Sarkar, 1999; Sarkar & Fuller, 2003). After the rediscovery of Mendel’s work in the early 1900s, some of the first geneticists were occupied with the problem of how animals and plants that reproduced by cloning or were of fixed genotypes could develop very different morphologies in different environments. As genetics developed, however, this question dropped to the wayside in the United States despite the best efforts of T. Dobzhansky and his student, Richard C. Lewontin (2000). Recently, phenotypic plasticity has been rediscovered in a variety of biological disciplines, from molecular genetics to evolutionary biology. But in developmental psychobiology, there has long been an interest in how behavior emerges (Gottlieb, 1992), and the approaches and concepts of this rich field have much to contribute to this newly emerging field in the biological sciences. Much of my work has addressed fundamental precepts in Behavioral Neuroendocrinology, focusing in particular on the evolution of reproductive behaviors and the neural mechanisms that control them (Crews, 2002). To this end, I have capitalized on experiments of nature, or naturally occurring species. But as a student of Danny Lehrman and Jay Rosenblatt at the Institute of Animal Behavior, I was familiar with the principles of developmental psychobiology, and the last decade has found me coming full circle back to these roots, largely for the reasons captured in the quote of George Michel and Celia Moore (1995) at the beginning of this article. It is in the arena of sex and sexuality that the biological concepts of phenotypic plasticity and the psychobiological principles of development come together. To illustrate this, I will begin by considering the distinction between sex and sexuality and how the study of the former informs, but does not explain, the latter. In so doing, I will describe an animal model system my laboratory has studied for the last decade, one that obviates some of the problems that are inherent in conventional animal models. This work focuses on what constitutes experience and how it influences the development of adult sexuality. Here, I consider the temporal nature and source of experience and how this might affect brain areas that are involved in the display of aggressive and sexual behaviors. I also will present some data on how changes in the brain can constrain future behavior before ending with some comments about transgenerational effects.

Jacques Balthazart – One of the best experts on this subject based on the ideXlab platform.

  • how technical progress reshaped Behavioral Neuroendocrinology during the last 50 years and some methodological remarks
    Hormones and Behavior, 2020
    Co-Authors: Jacques Balthazart

    Abstract:

    Abstract The first issue of Hormones and Behavior was published 50 years ago in 1969, a time when most of the techniques we currently use in Behavioral Endocrinology were not available. Researchers have during the last 5 decades developed techniques that allow measuring hormones in small volumes of biological samples, identify the sites where steroids act in the brain to activate sexual behavior, characterize and quantify gene expression correlated with behavior expression, modify this expression in a specific manner, and manipulate the activity of selected neuronal populations by chemogenetic and optogenetic techniques. This technical progress has considerably transformed the field and has been very beneficial for our understanding of the endocrine controls of behavior in general, but it did also come with some caveats. The facilitation of scientific investigations came with some relaxation of methodological exigency. Some critical controls are no longer performed on a regular basis and complex techniques supplied as ready to use kits are implemented without precise knowledge of their limitations. We present here a selective review of the most important of these new techniques, their potential problems and how they changed our view of the hormonal control of behavior. Fortunately, the scientific endeavor is a self-correcting process. The problems have been identified and corrections have been proposed. The next decades will obviously be filled with exciting discoveries in Behavioral Neuroendocrinology.

  • The Neuroendocrinology of reproductive behavior in Japanese quail.
    Domestic Animal Endocrinology, 2003
    Co-Authors: Jacques Balthazart, Michelle Baillien, Thierry Charlier, Charlotte Cornil, Gregory F. Ball

    Abstract:

    Sex steroid hormones such as testosterone have widespread effects on brain physiology and function but one of their best characterized effects arguably involves the activation of male sexual behavior. During the past 20 years we have investigated the testosterone control of male sexual behavior in an avian species, the Japanese quail (Coturnix japonica). We briefly review here the main features and advantages of this species relating to the investigation of fundamental questions in the field of Behavioral Neuroendocrinology, a field that studies inter-relationship among hormones, brain and behavior. Special attention is given to the intracellular metabolism of testosterone, in particular its aromatization into an estrogen, which plays a critical limiting role in the mediation of the Behavioral effects of testosterone. Brain aromatase activity is controlled by steroids which increase the transcription of the enzyme, but afferent inputs that affect the intraneuronal concentrations of calcium also appear to have a pronounced effect on the enzyme activity through rapid changes in its phosphorylation status. The physiological significance of these slow genomic and rapid, presumably non-genomic, changes in brain aromatase activity are also briefly discussed.

  • Do sex differences in the brain explain sex differences in the hormonal induction of reproductive behavior? What 25 years of research on the Japanese quail tells us.
    Hormones and Behavior, 1996
    Co-Authors: Jacques Balthazart, Omar Tlemçani, Gregory F. Ball

    Abstract:

    Abstract Early workers interested in the mechanisms mediating sex differences in morphology and behavior assumed that differences in behavior that are commonly observed between males and females result from the sex specificity of androgens and estrogens. Androgens were thought to facilitate male-typical traits, and estrogens were thought to facilitate female-typical traits. By the mid-20th century, however, it was apparent that administering androgens to females or estrogens to males was not always effective in sex-reversing behavior and that in some cases a “female” hormone such as an estrogen could produce male-typical behavior and an androgen could induce female-typical behavior. These conceptual difficulties were resolved to a large extent by the seminal paper of C. H. Phoenix, R. W. Goy, A. A. Gerall, and W. C. Young in (1959,Endocrinology65, 369–382) that illustrated that several aspects of sexual behavior are different between males and females because the sexes have been exposed during their perinatal life to a different endocrine milieu that has irreversibly modified their response to steroids in adulthood. Phoenixet al.(1959) therefore formalized a clear dichotomy between the organizational and activational effects of sex steroid hormones. Since this paper, a substantial amount of research has been carried out in an attempt to identify the aspects of brain morphology or neurochemistry that differentiate under the embryonic/neonatal effects of steroids and are responsible for the different Behavioral response of males and females to the activation by steroids in adulthood. During the past 25 years, research in Behavioral Neuroendocrinology has identified many sex differences in brain morphology or neurochemistry; however many of these sex differences disappear when male and female subjects are placed in similar endocrine conditions (e.g., are gonadectomized and treated with the same amount of steroids) so that these differences appear to be of an activational nature and cannot therefore explain sex differences in behavior that are still present in gonadectomized steroid-treated adults. This research has also revealed many aspects of brain morphology and chemistry that are markedly affected by steroids in adulthood and are thought to mediate the activation of behavior at the central level. It has been explicitly, or in some cases, implicitly assumed that the sexual differentiation of brain and behavior driven by early exposure to steroids concerns primarily those neuroanatomical/neurochemical characteristics that are altered by steroids in adulthood and presumably mediate the activation of behavior. Extensive efforts to identify these sexually differentiated brain characteristics over the past 20 years has only met with limited success, however. As regards reproductive behavior, in all model species that have been studied it is still impossible to identify satisfactorily brain characteristics that differentiate under early steroid action and explain the sex differences in Behavioral activating effects of steroids. This problem is illustrated by research conducted on Japanese quail (Coturnix japonica), an avian model system that displays prominent sex differences in the sexual Behavioral response to testosterone, and in which the endocrine mechanisms that control sexual differentiation of behavior have been clearly identified so that subjects with a fully sex-reversed Behavioral phenotype can be easily produced. In this species, studies of sex differences in the neural substrate mediating the action of steroids in the brain, including the activity of the enzymes that metabolize steroids such as aromatase and the distribution of steroid hormone receptors as well as related neurotransmitter systems, did not result in a satisfactory explanation of sex differences in the Behavioral effectiveness of testosterone. Possible explanations for the relative failure to identify the organized brain characteristics responsible for Behavioral sex differences in the responsiveness to steroids are presented. It is argued that novel research strategies may have to be employed to successfully attack the fundamental question of the hormonal mechanisms regulating sex differences in behavior.