Parental selection for growth and early-life low stocking density increase the female-to-male ratio in European sea bass.

In European sea bass (Dicentrarchus labrax), as in many other fish species, temperature is known to influence the sex of individuals, with more males produced at relatively high temperatures. It is however unclear to what extent growth or stress are involved in such a process, since temperature is known to influence both growth rate and cortisol production. Here, we designed an experiment aiming at reducing stress and affecting early growth rate. We exposed larvae and juveniles originating from both captive and wild parents to three different treatments: low stocking density, food supplemented with tryptophan and a control. Low stocking density and tryptophan treatment respectively increased and decreased early growth rate. Each treatment influenced the stress response depending on the developmental stage, although no clear pattern regarding the whole-body cortisol concentration was found. During sex differentiation, fish in the low-density treatment exhibited lower expression of gr1, gr2, mr, and crf in the hypothalamus when compared to the control group. Fish fed tryptophan displayed lower crf in the hypothalamus and higher level of serotonin in the telencephalon compared to controls. Overall, fish kept at low density produced significantly more females than both control and fish fed tryptophan. Parents that have been selected for growth for three generations also produced significantly more females than parents of wild origin. Our findings did not allow to detect a clear effect of stress at the group level and rather point out a key role of early sexually dimorphic growth rate in sex determination.

[NEUROENDOCRINE REPRODUCTIVE CENTERS OF CORTICOMEDIAL DIVISION OF THE AMYGDALA].

In this review for the first time systematized available in modern literature data, which characterize the structural and functional organization of the reproductive centers of corticomedial division of the Amygdala. Given information about physiological mechanisms of their involvement in the organization of sexual behavior, regulation of secretion and excretion of gonadotropines, influence on the processes of sexual maturation of organisms. Involvement of Amygdala in functional systems of the brain, which determine reproductive functions, predefined its participation in the processes of sexual differentiation of the brain. Important role in the implementation of reproductive functions plays the olfactory stimuli, which through the Amygdala switches to the centers of the pre-optic-hypothalamic region, which controls the secretion of gonadotropins and sexual behavior.

60 YEARS OF NEUROENDOCRINOLOGY: MEMOIR: Geoffrey Harris and my brush with his unit.

Geoffrey Harris is chiefly known for his demonstration of the control of the pituitary gland by the portal vessels coming from the hypothalamus. This does not do justice to his extraordinary contribution to biology. Harris' life's work was central in demonstrating the brain/body interactions by which animals and humans adapt to their environment, and above all the control of that most crucial and proximate of all evolutionary events - reproduction. In this brief review, I have tried to put Geoffrey Harris' work in the context of the scientific thinking at the time when he began his work, and above all, the contribution of his mentor, FHA Marshall, on whose towering shoulders Harris rose. But this is mainly my personal story, in which I have tried to show the debt that my work owed to Harris and especially to my dear friend, the late Keith Brown-Grant in Harris' team. I myself was never an endocrinologist, but over a short period in the early 1970s, under the influence of such inspirational mentors, and using purely anatomical methods, I was able to demonstrate sexual dimorphism and hormone-dependent sexual differentiation in the connections of the preoptic area, regeneration of the median eminence, the ultrastructure of apoptosis, the requirement for the suprachiasmatic nuclei in reproductive rhythms, the existence of non-rod or cone photoreceptors in the albino rat retina and, later, the expression of vasopressin by solitary (one in 600) magnocellular neurons in the polydipsic di/di Brattleboro mutant rat; this phenomenon was subsequently shown to be due to a+1 reading frameshift. I end this brief overview by mentioning some of the abiding and fascinating mysteries of the endocrine memory of the brain that arise from Harris' work on the control of the endocrines, and by pointing out how the current interest in chronobiology emphasises what a Cinderella the endocrine mechanisms have become in current brain imaging studies.

Sexual differentiation of the adolescent rodent brain: hormonal influences and developmental mechanisms.

This article is part of a Special Issue "Puberty and Adolescence". Sexual differentiation is the process by which the nervous system becomes structurally and functionally dissimilar in females and males. In mammals, this process has been thought to occur during prenatal and early postnatal development, when a transient increase in testosterone secretion masculinizes and defeminizes the developing male nervous system. Decades of research have led to the views that structural sexual dimorphisms created during perinatal development are passively maintained throughout life, and that ovarian hormones do not play an active role in feminization of the nervous system. Furthermore, perinatal testosterone was thought to determine sex differences in neuron number by regulating cell death and cell survival, and not by regulating cell proliferation. As investigations of neural development during adolescence became more prominent in the late 20th century and revealed the extent of brain remodeling during this time, each of these tenets has been challenged and modified. Here we review evidence from the animal literature that 1) the brain is further sexually differentiated during puberty and adolescence; 2) ovarian hormones play an active role in the feminization of the brain during puberty; and 3) hormonally modulated, sex-specific addition of new neurons and glial cells, as well as loss of neurons, contribute to sexual differentiation of hypothalamic, limbic, and cortical regions during adolescence. This architectural remodeling during the adolescent phase of sexual differentiation of the brain may underlie the known sex differences in vulnerability to addiction and psychiatric disorders that emerge during this developmental period.

Sex specific impact of perinatal bisphenol A (BPA) exposure over a range of orally administered doses on rat hypothalamic sexual differentiation.

Bisphenol A (BPA) is a high volume production chemical used in polycarbonate plastics, epoxy resins, thermal paper receipts, and other household products. The neural effects of early life BPA exposure, particularly to low doses administered orally, remain unclear. Thus, to better characterize the dose range over which BPA alters sex specific neuroanatomy, we examined the impact of perinatal BPA exposure on two sexually dimorphic regions in the anterior hypothalamus, the sexually dimorphic nucleus of the preoptic area (SDN-POA) and the anterioventral periventricular (AVPV) nucleus. Both are sexually differentiated by estradiol and play a role in sex specific reproductive physiology and behavior. Long Evans rats were prenatally exposed to 10, 100, 1000, 10,000µg/kg bw/day BPA through daily, non-invasive oral administration of dosed-cookies to the dams. Offspring were reared to adulthood. Their brains were collected and immunolabeled for tyrosine hydroxylase (TH) in the AVPV and calbindin (CALB) in the SDN-POA. We observed decreased TH-ir cell numbers in the female AVPV across all exposure groups, an effect indicative of masculinization. In males, AVPV TH-ir cell numbers were significantly reduced in only the BPA 10 and BPA 10,000 groups. SDN-POA endpoints were unaltered in females but in males SDN-POA volume was significantly lower in all BPA exposure groups. CALB-ir was significantly lower in all but the BPA 1000 group. These effects are consistent with demasculinization. Collectively these data demonstrate that early life oral exposure to BPA at levels well below the current No Observed Adverse Effect Level (NOAEL) of 50mg/kg/day can alter sex specific hypothalamic morphology in the rat.

Aromatase knockout mice show normal steroid-induced activation of gonadotrophin-releasing hormone neurones and luteinising hormone surges with a reduced population of kisspeptin neurones in the rostral hypothalamus.

We recently reported that female aromatase knockout (ArKO) mice show deficits in sexual behaviour and a decreased population of kisspeptin-immunoreactive neurones in the rostral periventricular area of the third ventricle (RP3V), resurrecting the question of whether oestradiol actively contributes to female-typical sexual differentiation. To further address this question, we assessed the capacity of ArKO mice to generate a steroid-induced luteinising hormone (LH) surge. Adult, gonadectomised wild-type (WT) and ArKO mice were given silastic oestradiol implants s.c. and, 1 week later, received s.c. injections of either oestradiol benzoate (EB) followed by progesterone, EB alone, or no additional steroids to activate gonadotrophin-releasing hormone (GnRH) neurones and generate an LH surge. Treatment with EB and progesterone induced significant Fos/GnRH double-labelling and, consequently, an LH surge in female WT and in ArKO mice of both sexes but not in male WT mice. ArKO mice of both sexes had fewer cells expressing Kiss-1 mRNA in the RP3V compared to female WT mice but had more Kiss-1 mRNA-expressing cells compared to WT males, reflecting an incomplete sexual differentiation of this system. To determine the number of cells expressing kisspeptin, the same experimental design was repeated in Experiment 2 with the addition of groups of WT and ArKO mice that were given EB + progesterone and sacrificed 2 h before the expected LH surge. No differences were observed in the number of kisspeptin-immunoreactive cells 2 h before and at the time of the LH surge. The finding that ArKO mice of both sexes have a competent LH surge system suggests that oestradiol has predominantly defeminising actions on the GnRH/LH surge system in males and that the steroid-induced LH surge can occur in females even with a greatly reduced population of kisspeptin neurones in the RP3V.

Galanin neurons in the intermediate nucleus (InM) of the human hypothalamus in relation to sex, age, and gender identity.

The intermediate nucleus (InM) in the preoptic area of the human brain, also known as the sexually dimorphic nucleus of the preoptic area (SDN-POA) and the interstitial nucleus of the anterior hypothalamus-1 (INAH-1) is explored here. We investigated its population of galanin-immunoreactive (Gal-Ir) neurons in relation to sex, age, and gender identity in the postmortem brain of 77 subjects. First we compared the InM volume and number of Gal-Ir neurons of 22 males and 22 females in the course of aging. In a second experiment, we compared for the first time the InM volume and the total and Gal-Ir neuron number in 43 subjects with different gender identities: 14 control males (M), 11 control females (F), 10 male-to-female (MtF) transsexual people, and 5 men who were castrated because of prostate cancer (CAS). In the first experiment we found a sex difference in the younger age group (<45 years of age), i.e., a larger volume and Gal-Ir neuron number in males and an age difference, with a decrease in volume and Gal-Ir neuron number in males > 45 years. In the second experiment the MtF transsexual group presented an intermediate value for the total InM neuron number and volume that did not seem different in males and females. Because the CAS group did not have total neuron numbers that were different from the intact males, the change in adult circulating testosterone levels does not seem to explain the intermediate values in the MtF group. Organizational and activational hormone effects on the InM are discussed.

Expression and distribution of P450-aromatase in the ovine hypothalamus at different stages of fetal development.

OBJECTIVES: An important step of sexual differentiation is the conversion of testosterone to estrogen by aromatase leading to masculinization and defeminization of the fetal brain areas crucial for normal sexual behavior and reproduction. Brain sexual differentiation occurs throughout a critical period starting from different prenatal stages depending on the species. Such period goes on from gestation day (GD) 30 to 100GD in the sheep. The fetal sheep brain is reported to aromatize androgens to estrogens at 64GD. The main goal of this work was to evaluate aromatase expression in sheep hypothalami during the whole period of sexual differentiation (35GD, 55GD, 80GD, 115GD) and whether differences may be observed depending on gestational stage and sex. METHODS: Sections at the hypothalamic level underwent immunoperoxidase technique employing anti-aromatase and anti-androgen receptor antibodies. Samples from 35GD and 55GD were also processed with in situ hybridization using aromatase cDNA probe. Blot analyses were performed to quantify possible aromatase immunoexpression differences between sexes. For sexing, samples at 35GD and 55GD underwent DNA extraction and SRY amplification. RESULTS: Our results revealed aromatase and androgen receptor immunoreactivity along the whole period of sexual differentiation. Both molecules were detected in many brain regions and markedly in the periventricular area. The highest aromatase and androgen receptor amounts were observed at 35GD and 55GD, when aromatase was more abundant in females than in males. CONCLUSIONS: In conclusion, the sheep can be included among the species where aromatase is highly expressed in the hypothalamus during the whole period of sexual differentiation.

Organized for sex - steroid hormones and the developing hypothalamus.

Steroid hormones of gonadal origin act on the neonatal brain, particularly the hypothalamus, to produce sex differences that underlie copulatory behavior. Neuroanatomical sex differences include regional volume, cell number, connectivity, morphology, physiology, neurotransmitter phenotype and molecular signaling, all of which are determined by the action of steroid hormones, particularly by estradiol in males, and are established by diverse downstream effects. Sex differences in distinct hypothalamic regions can be organized by the same steroid hormone, but the direction of a sex difference is often specific to one region or cell type, illustrating the wide range of effects that steroid hormones have on the developing brain. Substantial progress has been made in elucidating the downstream mechanisms through which gonadal hormones sexually differentiate the brain, but gaps remain in establishing the precise relationship between changes in neuronal morphology and behavior. A complete understanding of sexual differentiation will require integrating the diverse mechanisms across multiple brain regions into a functional network that regulates behavioral output.

Sexual differentiation of the human brain in relation to gender identity and sexual orientation.

It is believed that during the intrauterine period the fetal brain develops in the male direction through a direct action of testosterone on the developing nerve cells, or in the female direction through the absence of this hormone surge. According to this concept, our gender identity (the conviction of belonging to the male or female gender) and sexual orientation should be programmed into our brain structures when we are still in the womb. However, since sexual differentiation of the genitals takes place in the first two months of pregnancy and sexual differentiation of the brain starts in the second half of pregnancy, these two processes can be influenced independently, which may result in transsexuality. This also means that in the event of ambiguous sex at birth, the degree of masculinization of the genitals may not reflect the degree of masculinization of the brain. There is no proof that social environment after birth has an effect on gender identity or sexual orientation. Data on genetic and hormone independent influence on gender identity are presently divergent and do not provide convincing information about the underlying etiology. To what extent fetal programming may determine sexual orientation is also a matter of discussion. A number of studies show patterns of sex atypical cerebral dimorphism in homosexual subjects. Although the crucial question, namely how such complex functions as sexual orientation and identity are processed in the brain remains unanswered, emerging data point at a key role of specific neuronal circuits involving the hypothalamus.

Roles of kisspeptins in the control of hypothalamic-gonadotropic function: focus on sexual differentiation and puberty onset.

Kisspeptins, a family of peptides encoded by the Kiss1 gene that act via the G protein-coupled receptor 54 (GPR54 or Kiss1R), were initially catalogued as metastasis suppressors, but have recently emerged as pivotal gatekeepers of puberty onset and reproductive function. Indeed, since the seminal observations (in late 2003) that inactivating mutations of GPR54 are coupled to absence of puberty and hypogonadotropic hypogonadism in human and mice, a large number of experimental studies, conducted in different species, including humans, have substantiated the roles of kisspeptins and GPR54 as essential elements in the physiologic regulation of key aspects of reproductive maturation and function. These appear to include, among others, the process of brain sexual differentiation during critical (early) periods of maturation and the timing of puberty onset. Recent exciting developments in these particular areas will be comprehensively reviewed herein. These functions, together with the proven roles of kisspeptins in the control of GnRH neurons and the transmission ofthe regulatory actions of key signals, such as sex steroids, metabolic hormones and environmental cues, point out that the Kiss1 system is an indispensable player of the reproductive brain, whose discovery is now considered as (one of) the most important findings in reproductive physiology in the last decades.

Diferenciación sexual: el factor de Jost / Sexual differentiation: the Jost factor

El estudio de la diferenciación sexual de los mamíferos es, sinduda, un ejemplo relevante de proceso epigénetico producido por lainteracción entre genoma y hormonas secretadas por los testículos fetales: la testosterona y la hormona anti-Müllerian. La diferenciación sexual se produce a nivel periférico, en las gónadas y, también, a nivel cerebral, hipotálamico, en dos vertientes: la neuroendocrina y la de conducta sexual. Ambas vertientes del dimorfismo sexual cerebral pueden ser estudiadas en rata. La primera, por la ovulación, o no, que se produce en un ovario trasplantado en la cavidad abdominal de ratas hembras o en machos, los cuales son, ambos, castrados, previamente al nacimiento, y, la segunda, por la postura de lordosis, que presentan las ratas hembras, debidamente diferenciadas sexualmente, frente al macho. Se han localizado las diferentes zonas cerebrales en donde existen receptores para estrógenos. En la diferenciación periférica o gonadal el diferenciador es el testículo fetal que secreta dos hormonas. La testosterona que mantiene y diferencia los canales Wolff en vasos deferentes, epidídimo y vesículas seminales y la hormona anti-Müllerian (AMH) que provoca la regresión de los canales de Müller, todo ello, en el embrión genéticamente macho. En el cual se diferencian, previamente, los testículos en la etapa fetal de desarrollo de gónadas. En el embrión hembra, sin testículos, y consecuentemente sin testosterona ni AMH, los canales de Wolff involucionan y los de Müller, de forma espontánea, se diferencian en útero, trompas de Falopio y parte superior de la vagina. El conocimiento y aclaración de dichas cuestiones pudo establecerse por el descubrimiento, en fetos de conejos, hecho por el Profesor Alfred Jost, en París (1947-50), de la hormona anti-Müllerian (AMH). Actualmente, la AMH se presenta con múltiples funciones, aunque la más fundamental sea la de regresión de los canales Müllerianen los fetos genéticamente masculinos. Esta hormona es, además, un marcador de patologías como las neoplasias ováricas o la anormal esteroidogénesis del ovario y su hallazgo aclara todo el heterogéneo grupo de patologías de intersexualidad gonadal. Se ha clonado su gen y se han preparado sus anticuerpos. Por pertenecer a la familia del TGFβ (factor de crecimiento transformanteβ) cuyos miembros están implicados en procesos neoplásicos está siendo, actualmente, muy estudiada. Tanto sus posibles aplicaciones en terapéutica, como sus funciones en adulto, son aún investigaciones abiertas al futuro (AU)

Sexual differentiation: the Jost factor Sexual differentiation in mammals is a good example of the epigenetic process produced by the interaction between the genome and hormones secreted by the fetal testes: testosterone and anti-Müllerian hormone (AMH).Sexual differentiation takes place in the gonads and brain(hypothalamus) in two branches: neuroendocrine and sexual behavior. Both branches of the cerebral sexual dimorphism can be studied in the rat. The former by the ovulation pattern of an ovary transplanted in the abdominal cavity of male or female rats which are castrated at birth. The latter can be examined by the response of lordosis of female rats with plain sexual differentiation in front ofthe male. The different brain regions containing estrogen receptors have been localized. Fetal testes regulate gonadal differentiation through two hormones; testosterone an anti-Müllerian hormone. Testosterone differentiates Wolff channels in deferent vessels, epididimus and seminal vesicles, and AMH induces the regression of Müller channels in the genetically male embryo, in which testes are previously differentiated in the last fetal stage of gonad development. In the female, with no testosterone or AMH, the Wolff channels undergo involution and those of Müller spontaneously differentiate to uterus, Fallopian trumps and upper part of vagina. The credit for the knowledge of these matters should be given to Prof. Alfred Jost (Paris, 1947-50), who discovered AMH in rabbit fetuses. Currently, AMH has been endowed with many biological functions, the most important being the involution of Müllerian channels in genetically male fetuses. AMH is a biomarker of diseases such as ovarian tumors and abnormal steroid synthesis in ovary and its finding helped explain a heterogeneous number of sexual-related pathologies. AMH gene has been cloned and anti-AMH monoclonal antibodies obtained. Since AMH has been associated with the transforming growth factor beta (TGF-β) family, whose members are involved in cancer processes, its biological functions and potential therapeutic applications are currently and will certainly be subject of intense studies (AU)

Significance of neonatal testicular sex steroids to defeminize anteroventral periventricular kisspeptin neurons and the GnRH/LH surge system in male rats.

The brain mechanism regulating gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) release is sexually differentiated in rodents. Kisspeptin neurons in the anteroventral periventricular nucleus (AVPV) have been suggested to be sexually dimorphic and involved in the GnRH/LH surge generation. The present study aimed to determine the significance of neonatal testicular androgen to defeminize AVPV kisspeptin expression and the GnRH/LH surge-generating system. To this end, we tested whether neonatal castration feminizes AVPV kisspeptin neurons and the LH surge-generating system in male rats and whether neonatal estradiol benzoate (EB) treatment suppresses the kisspeptin expression and the LH surge in female rats. Immunohistochemistry, in situ hybridization, and quantitative real-time RT-PCR were performed to investigate kisspeptin and Kiss1 mRNA expressions. Male rats were castrated immediately after birth, and females were treated with EB on postnatal Day 5. Neonatal castration caused an increase in AVPV kisspeptin expression at peptide and mRNA levels in the genetically male rats, and the animals showed surge-like LH release in the presence of the preovulatory level of estradiol (E2) at adulthood. On the other hand, neonatal EB treatment decreased the number of AVPV kisspeptin neurons and caused an absence of E2-induced LH surge in female rats. Semiquantitative RT-PCR analysis showed that neonatal steroidal manipulation affects Kiss1 expression but does not significantly affect gene expressions of neuropeptides (neurotensin and galanin) and enzymes or transporter for neurotransmitters (gamma-aminobutyric acid, glutamate, and dopamine) in the AVPV, suggesting that the manipulation specifically affects Kiss1 expressions. Taken together, our present results provide physiological evidence that neonatal testicular androgen causes the reduction of AVPV kisspeptin expression and failure of LH surge in genetically male rats. Thus, it is plausible that perinatal testicular androgen causes defeminization of the AVPV kisspeptin system, resulting in the loss of the surge system in male rats.

Dual roles of cyp19a1a in gonadal sex differentiation and development in the protandrous black porgy, Acanthopagrus schlegeli.

Protandrous black porgy fish, Acanthopagrus schlegeli, have a striking life cycle, with male sex differentiation at the juvenile stage, a bisexual gonad during first 2 yr of life, and a male-to-female sex change (with vitellogenic oocytes) at 3 yr of age. The present study investigated the role of aromatase (cyp19a1a/Cyp19a1a) in gonadal development in this species, especially in relation to sexual differentiation and sex change. Fish of various ages were treated with estradiol (E2) or aromatase inhibitor (AI) to determine whether manipulation of the hormonal environment has an impact on these processes. We report an integrative immunohistochemical, cellular, and molecular data set describing these interesting phenomena. During male sex differentiation, high levels of cyp19a1a/Cyp19a1a expression were observed in the undifferentiated gonad (4 mo of age), in marked contrast to the low cyp19a1a/Cyp19a1a levels detected in the differentiated testis at the age of 5-6 mo. A low dose of E2 (0.25 mg/kg feed) stimulated testicular growth and function in sexually differentiated fish, whereas a high dose of E2 (6 mg/kg feed) induced female development. Furthermore, administration of AI suppressed male development and promoted female sexual differentiation. An increased number of figla transcripts (an oocyte-specific gene) were observed prior to cyp19a1a expression, concomitant with the development of oogonia and early primary oocytes in the ovaries of both E2- and AI-treated groups. Immunohistochemical Pcna staining showed that the regression of testicular tissue occurred prior to the development of ovarian tissue in both E2- and AI-induced females. The importance of cyp19a1a in female development was further demonstrated by the increase in cyp19a1a transcripts during the naturally occurring sex change. Transcripts of foxl2 increased in the gonads of 2- to 3-yr-old black porgy during the early stages of the natural sex change, followed by a gradual elevation of cyp19a1a levels. The levels of both genes peaked in the resulting ovarian tissue. Thus, cyp19a1a/Cyp19a1a plays dual roles in the gonadal development, namely, in testicular development during the initial period of sexual differentiation and later in ovarian development during the natural sex change.

Androgen receptors are required for full masculinization of nitric oxide synthase system in rat limbic-hypothalamic region.

The neuronal nitric oxide synthase (nNOS) is involved in the control of male and female sexual behavior and its distribution in several regions of the limbic-hypothalamic system, as well as its coexistence with gonadal hormones' receptors, suggests that these hormones may play a significant role in controlling its expression. However, data illustrating the role of gonadal hormones in controlling the nNOS expression are, at present, contradictory, even if they strongly suggest an involvement of testosterone (T) in the regulation of nNOS. The action of T may be mediated through androgen (AR) or, after aromatization to estradiol (E(2)), through estrogen receptors. To elucidate the role of AR on nNOS expression, we compared male and female rats with a non-functional mutation of AR (Tfm, testicular feminization mutation) to their control littermates. We investigated some hypothalamic and limbic nuclei involved in the control of sexual behavior [medial preoptic area (MPA), paraventricular (PVN), arcuate (ARC), ventromedial (VMH) and stria terminalis (BST) nuclei]. In BST (posterior subdivision), VMH (ventral subdivision), and MPA we detected a significant sexual dimorphism in control animals and a decrease of nNOS positive elements in Tfm males compared to their littermate. In addition, we observed a significant increase of nNOS positive elements in BST (posterior) of Tfm females. No significant changes were observed in the other nuclei. These data indicate that, contrary to current opinions, androgens, through the action of AR may have a relevant role in the organization and modulation of the nNOS hypothalamic system.

Primary cell cultures from fetal bovine hypothalamus and cerebral cortex: a reliable model to study P450Arom and alpha and beta estrogen receptors in vitro.

Estrogens synthesized by neural P450 aromatase (P450Arom) are implicated in many aspects of mammalian brain development and particularly in sexual differentiation of the central nervous system (CNS). This study analyzes the usefulness of an in vitro model based on bovine primary cell cultures from the hypothalamus and frontal cortex to investigate the role of P450Arom and estrogen receptors (ERs) in the development of fetal neural structures. The mRNA expression of P450Arom, ERalpha and ERbeta was detected using RT-PCR analysis in both hypothalamic and cortical primary cell cultures. P450Arom was identified and localized by immunocytochemistry in both neurons and astrocytes. Our results indicate that, within our experimental settings, astrocytes do not express ERalpha. The experimental model that we propose may represent a standardized dynamic model to study cellular and molecular mechanisms involved in the complex process of brain sexual differentiation.

Rainbow trout gonadal masculinization induced by inhibition of estrogen synthesis is more physiological than masculinization induced by androgen supplementation.

The present study was designed to obtain new insights into fish gonadal sex differentiation by comparing the effects of two different masculinizing treatments on some candidate gene expression profiles. Masculinization was induced in rainbow trout, Oncorhynchus mykiss, genetic all-female populations using either an active fish androgen (11betaAnd, 11beta-hydroxyandrostenedione) or an aromatase inhibitor (ATD, 1,4,6-androstatriene-3,17-dione). The expression profiles of 100 candidate genes were obtained by real-time RT-PCR, and 46 profiles displayed a significant differential expression between control populations (males and females) and ATD/11betaAnd-treated populations. These expression profiles were grouped in four temporally correlated expression clusters. Among the common responses shared by the two masculinizing treatments, the inhibition of some early female differentiating genes (cyp19a1, foxl2a, fst, and fshb) appears to be crucial for effective masculinization, suggesting that these genes act together via a short regulation loop to maintain high sex-specific ovarian expression of cyp19a1. This simultaneous down-regulation of female-specific genes could be triggered by some testicular genes, such as dmrt1, nr0b1 (also known as dax1), and pdgfra, which are quickly up-regulated by the two masculinizing treatments. In contrast to 11betaAnd, ATD quickly restored the expression levels of steroidogenesis related genes (cyp11b2.1, cyp11b2.2, hsd3b1, cyp17a, star, and nr5a1) and some Sertoli cell markers (sox9a2 and amh) to the expression levels observed during control testicular differentiation. This demonstrates that these genes are probably not needed for active masculinization and that the inhibition of endogenous estrogen synthesis produces a much more complete and specific testicular pattern of gene expression than that observed following androgen-induced masculinization.

[Women, bodies, and Hebrew medieval medical literature]. / Mujeres, cuerpos y literatura médica medieval en hebreo.

This essay explores different views on the female body articulated within Hebrew medieval texts on women's health care. It also investigates whether texts also integrate women's own perceptions of their bodies, and of their needs and care. I have analysed how this genre of Hebrew literature understood two key issues in the construction of sexed bodies: menstruation and cosmetics.

Characterization and expression profile of the ovarian cytochrome P-450 aromatase (cyp19A1) gene during thermolabile sex determination in pejerrey, Odontesthes bonariensis.

Cytochrome P450 aromatase (cyp19) is an enzyme that catalyzes the conversion of androgens to estrogens and may play a role in temperature-dependent sex determination (TSD) of reptiles, amphibians, and fishes. In this study, the ovarian P450 aromatase form (cyp19A1) of pejerrey Odontesthes bonariensis, a teleost with marked TSD, was cloned and its expression profile evaluated during gonadal differentiation at feminizing (17 degrees C, 100% females), mixed-sex producing (24 and 25 degrees C, 73.3 and 26.7% females, respectively), and masculinizing (29 degrees C, 0% females) temperatures. The deduced cyp19A1 amino acid sequence shared high identity (>77.8%) with that from other teleosts but had low identity (<61.8%) with brain forms (cyp19A2), including that of pejerrey itself. The tissue distribution analysis of cyp19A1 mRNA in adult fish revealed high expression in the ovary. Semi-quantitative reverse transcription polymerase chain reaction analysis of the bodies of larvae revealed that cyp19A1 expression increased before the appearance of the first histological signs of ovarian differentiation at the feminizing temperature but remained low at the masculinizing temperature. The expression levels at mixed-sex producing temperatures were bimodal rather than intermediate, showing low and high modal values similar to those at the feminizing and masculinizing temperatures, respectively. The population percentages of high and low expression levels at intermediate temperatures were proportional to the percentage of females and males, respectively, and high levels were first observed at about the time of sex differentiation of females. These results suggest that cyp19A1 is involved in the process of ovarian formation and possibly also in the TSD of pejerrey.

Neuronal nitric oxide synthase and calbindin delineate sex differences in the developing hypothalamus and preoptic area.

Throughout the hypothalamus there are several regions known to contain sex differences in specific cellular, neurochemical, or cell grouping characteristics. The current study examined the potential origin of sex differences in calbindin expression in the preoptic area and hypothalamus as related to sources of nitric oxide. Specific cell populations were defined by immunoreactive (ir) calbindin and neuronal nitric oxide synthase (nNOS) in the preoptic area/anterior hypothalamus (POA/AH), anteroventral periventricular nucleus (AVPv), and ventromedial nucleus of the hypothalamus (VMN). The POA/AH of adult mice was characterized by a striking sex difference in the distribution of cells with ir-calbindin. Examination of the POA/AH of androgen receptor deficient Tfm mice suggests that this pattern was in part androgen receptor dependent, since Tfm males had reduced ir-calbindin compared with wild-type males and more similar to wild-type females. At P0 ir-calbindin was more prevalent than in adulthood, with males having significantly more ir-calbindin and nNOS than have females. Cells that contained either ir-calbindin or ir-nNOS in the POA/AH were in adjacent cell groups, suggesting that NO derived from the enzymatic activity of nNOS may influence the development of ir-calbindin cells. In the region of AVPv, at P0, there was a sex difference with males having more ir-nNOS fibers than have females while ir-calbindin was not detected. In the VMN, at P0, ir-nNOS was greater in females than in males, with no significant difference in ir-calbindin. We suggest that NO as an effector molecule and calbindin as a molecular biomarker illuminate key aspects of sexual differentiation in the developing mouse brain.