Gonadal Sex Steroids Research Articles

Orphan nuclear receptor ftz-f1 (NR5A3) promotes egg chamber survival in the Drosophila ovary.

Gamete production in mammals and insects is controlled by cell signaling pathways that facilitate communication between germ cells and somatic cells. Nuclear receptor signaling is a key mediator of many aspects of reproduction, including gametogenesis. For example, the NR5A subfamily of nuclear receptors is essential for gonad development and sex steroid production in mammals. Despite the original identification of the NR5A subfamily in the model insect Drosophila melanogaster, it has been unclear whether Drosophila NR5A receptors directly control oocyte production. Ftz-f1 is expressed throughout the ovary, including in germline stem cells, germline cysts, and several populations of somatic cells. We show that ftz-f1 is required in follicle cells prior to stage 10 to promote egg chamber survival at the mid-oogenesis checkpoint. Our data suggest that egg chamber death in the absence of ftz-f1 is due, at least in part, to failure of follicle cells to exit the mitotic cell cycle or failure to accumulate oocyte-specific factors in the germline. Taken together, these results show that, as in mammals, the NR5A subfamily promotes maximal reproductive output in Drosophila. Our data underscore the importance of nuclear receptors in the control of reproduction and highlight the utility of Drosophila oogenesis as a key model for unraveling the complexity of nuclear receptor signaling in gametogenesis.

Celebrating 50+ years of research on the reproductive biology and endocrinology of the green frog: An overview

This issue is dedicated to the late Professor Giovanni Chieffi, and this article is an overview of the research on Comparative Endocrinology of reproduction using Rana esculenta (alias Pelophylax esculentus) as a model system. Starting from the early 1970s till today, a large quantity of work have been conducted both in the fields of experimental endocrinology and in the definition of the diffuse neuroendocrine system, with a major focus on the increasing role of regulatory peptides. The various aspects investigated concerned the histological descriptions of principal endocrine glands of the hypothalamic–pituitary–gonadal (HPG) axis, the localization and distribution in the HPG of several different substances (i.e. neurosteroids, hypothalamic peptide hormones, pituitary gonadotropins, gonadal sex steroids, and other molecules), the determination of sex hormone concentrations in both serum and tissues, the hormone manipulations, as well as the gene and protein expression of steroidogenic enzymes and their respective receptors. All together these researches, often conducted considering different periods of the annual reproductive cycle of the green frog, allowed to understand the mechanism of cascade control/regulation of the HPG axis of R. esculenta, characterizing the role of different hormones in the two sexes, and testing the hypotheses about the function of single hormones in different target organs. It becomes evident from the review that, in their simplest form, several features of this species are specular as compared to those of other vertebrate species and that reproduction in this frog species is either under endogenous multi-hormonal control or by a wide array of different factors. Our excursus of this research, spanning almost five decades, shows that R. esculenta has been intensively and successfully used as an animal model in reproductive endocrinology as well as several field studies such as those involving environmental concerns that focus on the effects of endocrine disruptors and other environmental contaminants.

SUN-265 Reduced Locomotive Behaviour and Increased Arcuate Nucleus Inflammation Are Observed in KISS1R KO Male Mice

The neuropeptide kisspeptin, encoded by the Kiss1 gene, binds the G- protein-coupled receptor Kiss1r (also known as GPR54) and is a novel player in the delicate balance of energy intake and expenditure. Mice that have a dysfunctional gene for Kiss1r develop an obese and diabetic phenotype. To further study how kisspeptin signalling impacts on energy balance, we investigated the relationship between absent kisspeptin signalling and locomotor behaviour in Kiss1rKO and wild type mice. Mice had free access to running wheels, and we examined the characteristics of wheel running over three weeks, and its flow-on effects on body mass. We subsequently examined dopaminergic neurons (via tyrosine hydroxylase (TH) staining) and hypothalamic inflammation (via Iba1 stained microglia). These studies also were performed following gonadectomy (GDX), to control for gonadal steroids. In intact males, the knockout (KO) mice covered only 10% of the distance travelled by wild-type (WT) per 24h (WT, 6363±643m; KO, 652±219m; P<0.0001). Moreover, in the WT there was a clear circadian pattern to the wheel-running activity, with most activity during lights off, while in the KO the running appeared randomly distributed across the 24h. After GDX, KO males continued to run significantly less than their WT counterparts (WT, 1652±474m; KO, 998±219m). In intact females, the KO mice covered only 23% of the distance travelled by WT per 24h (WT, 6030±747m; KO, 1379±364m; P<0.004). In OVX females, there was no difference between WT and KO mice (WT, 4150±1367m; KO, 3117±830m). Bodyweight analysis showed that access to running wheels prevented obesity usually seen in the Kiss1rKO mouse. In fact, in GDX males and females (at days 21 and 22 of wheel running) the KO mice were significantly lighter than WTs (at day 22: males, WT 28.67g; KO, 23.70g; P<0.05; females, WT, 27.38g; KO, 23.30g; P<0.05). Examination of TH revealed no significant difference in expression in the different genotypes in both sexes, in all areas examined. Investigation of Iba1 revealed significant higher counts in the male KO compared to the WT in the arcuate nucleus, but no difference in any other regions. We show that the locomotor activity in male and female Kiss1r KO mice is heavily dependent on the status of gonadal sex steroids. However, the lower running activity in male KO compared to WT remained after GDX, and this was paired with an elevated inflammation marker in the arcuate nucleus. Whether absent kisspeptin signalling acts as a significant regulator of voluntary activity is debatable, but patterns of locomotion behaviour could be disrupted, potentially involving circadian rhythm, this is under further investigation.

Prolonged use of finasteride-induced gonadal sex steroids alterations, DNA damage and menstrual bleeding in women.

The aim of the present study was to examine the effect of prolonged use of finasteride on serum levels of dihydrotestosterone (DHT), estradiol (E2), progesterone, testosterone and androstenedione in women during the menstrual period. Further, to screen and compare the 5α-reductase activities through the expression of SRD5A1, SRD5A2 and AR gene and to determine the level of VEGF, VKOR and SAA gene expression and DNA damage. A total of 30 Saudi women aged between 25 and 35 years were enrolled in the study. The selected women were divided into two groups. The first group (n = 15) received 5 mg finasteride/day for prolonged period of one year and second group (n = 15) was taken as a healthy control. ELISA technique was used for measuring the serum levels of the targeted hormones, and Comet assay was used for checking the DNA integrity. Our findings revealed significant decrement of DHT, E2, progesterone and androstenedione levels and elevated levels of testosterone in group treated with daily oral doses of 5 mg finasteride/day compared with the control subjects. mRNA expression suggested that finasteride has concrete effects on the gene expression of the selected genes from the treated group in comparison with the control group. In addition, finasteride induced DNA damage, and heavy menstrual bleeding was noted in women treated with finasteride. In conclusion, the present findings revealed that finasteride has adverse health effects in women associated with gonadal sex steroids alterations, DNA damage and heavy menstrual bleeding with no consensus in the treatment of androgenetic alopecia in women.

Chapter 1 - Neuroendocrine mechanisms of reproduction

The neuroendocrinology of reproduction focuses on the neuromodulation of gonadotropin-releasing hormone (GnRH), the ontogeny of the hypothalamic-pituitary-gonadal axis, and common reproductive events and conditions, namely, puberty, the menstrual cycle, and disorders of reproductive function. The core concept underpinning the neuroendocrinology of reproduction is neuroregulation of hypothalamic GnRH drive. In both men and women, reproductive function requires that GnRH input elicit appropriate secretion of follicle-stimulating hormone and luteinizing hormone from the anterior pituitary and that the gonads respond to such input appropriately. Moreover, insufficient GnRH drive causes hypothalamic hypogonadism and secondary insufficiency of gonadal sex steroid hormone synthesis and release in both sexes. Alterations in GnRH drive also reflect gonadal conditions such as dysgenesis, hyperandrogenism, gonadotropin mutations, and aging and loss or absence of oocytes or Sertoli cells. The most common cause of insufficient GnRH drive is functional, that is, due to the endocrine effects of psychologic or behavioral variables. Rarely does reduced GnRH drive reflect organic or congenital causes such as developmental defects, brain tumors, or celiac disease. Despite a common neuropathogenesis the heterogeneity of behavioral variables associated with reduced GnRH drive has resulted in a variety of names, including functional hypothalamic amenorrhea, stress-induced anovulation, and psychogenic amenorrhea.

Sex, stress and steroids.

The hypothalamo-pituitary-adrenal (HPA) axis plays a key role in the neuroendocrine response to stress and in maintaining physiological homoeostasis. However, stress that is chronic in nature can lead to HPA axis dysfunction and increase the risk for developing affective disorders, particularly if the stress is experienced during vulnerable periods in life. Sex differences in how the HPA axis responds to stress are well established, with females typically displaying heightened responses. The underlying cause of these sex differences is important to understand, as many neuropsychiatric disorders disproportionately affect females. Much research has provided evidence for gonadal sex steroids in underpinning sex differences in HPA axis responsivity; however, we suggest that neuroactive metabolites of these steroids also play a key role in the brain in mediating sex differences in HPA axis responses to stress. The relationship between neuroactive steroids and stress is complex. Acute stress rapidly increases neuroactive steroid production, which can in turn modulate activity of the HPA axis. However, under chronic stress conditions, stress can impact the brain's capacity to generate steroids, and this in turn has corollary effects on HPA axis function that may increase the propensity for psychopathology, given both HPA axis dysfunction and deficits in neuroactive steroids are implicated in affective disorders. Hence, here we review the evidence from animal and human studies for sex differences in the interactions between neuroactive steroids and the stress axis at various stages of life, under physiological and pathophysiological stress conditions and consider the implications for health and disease.

SAT-409 A Novel Population of Kisspeptin Neurons in the Medial Tuberal Nucleus of the Hypothalamus in Mice

Kisspeptin, encoded by Kiss1, stimulates GnRH release and is required for puberty onset and reproduction. Kiss1 neurons primarily reside in the hypothalamus, in the AVPV/PeN and ARC nuclei; however, smaller Kiss1 neuronal populations exist in other regions such as the medial amygdala, bed nucleus of the stria terminalis, and lateral septum. We identified a novel population of Kiss1 neurons in the lateral hypothalamus, specifically in the medial tuberal nucleus (MTu), in mice. A similar, small population of Kiss1 neurons in this lateral hypothalamic region was also newly identified in sheep (Moore et al., 2018), but nothing is known about the regulation or function of these Kiss1 neurons. Using both in situ hybridization in normal mice and fluorescent TdTomato expression in KissCre+/TdTomato+ mice, we confirmed the presence of Kiss1 neurons in the MTu of adult mice. Next, we examined the developmental time course of Kiss1 expression in the MTu by looking at TdTomato expression in KissCre+/TdTomato+ mice at different developmental ages (prepubertal, pubertal, and adult). We found that TdTomato expression in the MTu increased around puberty, perhaps as a result of increasing gonadal sex steroids. Estradiol (E2) regulates Kiss1 expression in all previously-identified Kiss1 neuronal populations and thus, we next examined whether E2 regulates MTu Kiss1 expression. We found that like the AVPV and extra-hypothalamic Kiss1 populations, Kiss1 expression in the MTu is upregulated by E2. In addition to E2, GABABR signaling is known to regulate extra-hypothalamic Kiss1 expression, while having no impact on AVPV/PeN and ARC Kiss1 expression. We examined if GABABR signaling regulates MTu Kiss1 expression by comparing Kiss1 expression in WT and GABABR KO mice. Like the other hypothalamic Kiss1 populations in the AVPV and ARC, Kiss1 expression in the MTu does not appear to be strongly regulated by GABABR signaling in male mice. Additional research is ongoing to further characterize these E2-regulated MTu Kiss1 neurons and elucidate their function(s).

Disruption of deiodinase type 2 in zebrafish disturbs male and female reproduction.

Thyroid hormones are crucial mediators of many aspects of vertebrate life, including reproduction. The key player is the biologically active 3,5,3'-triiodothyronine (T3), whose local bio-availability is strictly regulated by deiodinase enzymes. Deiodinase type 2 (Dio2) is present in many tissues and is the main enzyme for local T3 production. To unravel its role in different physiological processes, we generated a mutant zebrafish line, completely lacking Dio2 activity. Here we focus on the reproductive phenotype studied at the level of offspring production, gametogenesis, functioning of the hypothalamic-pituitary-gonadal axis and sex steroid production. Homozygous Dio2-deficient zebrafish were hypothyroid, displayed a delay in sexual maturity, and the duration of their reproductive period was substantially shortened. Fecundity and fertilization were also severely reduced. Gamete counts pointed to a delay in oogenesis at onset of sexual maturity and later on to an accumulation of oocytes in mutant ovaries due to inhibition of ovulation. Analysis of spermatogenesis showed a strongly decreased number of spermatogonia A at onset of sexual maturity. Investigation of the hypothalamic-pituitary-gonadal axis revealed that dysregulation was largely confined to the gonads with significant upregulation of igf3, and a strong decrease in sex steroid production concomitant with alterations in gene expression in steroidogenesis/steroid signaling pathways. Rescue of the phenotype by T3 supplementation starting at 4 weeks resulted in normalization of reproductive activity in both sexes. The combined results show that reproductive function in mutants is severely hampered in both sexes, thereby linking the loss of Dio2 activity and the resulting hypothyroidism to reproductive dysfunction.

Environmental exposure to oestrogenic endocrine disruptors mixtures reflecting on gonadal sex steroids and gametogenesis of the neotropical fish Astyanax rivularis

Discharge of municipal wastewater promotes the entry of diverse oestrogenic compounds into the water bodies. This complex mixture of substances interferes in the steroidogenic pathway, being able to promote severe reproductive impairment in freshwater fish populations. The purpose of the present study was to evaluate the effects of oestrogenic endocrine disruptors (EDCs) mixture on gonadal sex steroids (testosterone, T; 11-ketotestosterone, 11-KT; 17β-oestradiol, E2; 17-hydroxyprogesterone, 17-OHP) in the peak of the reproductive season of Astyanax rivularis, correlating the results obtained with the proportion of germ cells and gonadal histopathology. Three sampling sites were chosen to conduct the study, one reference site (S1), without contamination by municipal wastewater and two sites (S2 and S3) receiving discharge of municipal wastewater. Males of A. rivularis presented higher concentrations of E2, lower androgens (T and 11-KT) in gonads when compared to males from site S1. Concentrations of 17-OHP did not present significant difference among sites. In sites S2 and S3, the proportion of early spermatocytes, spermatids and Leydig cells increased while spermatozoa decreased compared to fish from S1. The following gonadal histopathologies were detected in the male fishes: intersex gonads (28% in S3) and testicular degeneration with germinal epithelium exhibiting agglutinated germ cells masses and empty cysts (57% in S2 and 71% in S3). In females, concentrations of T, E2 and 17-OHP did not present significant difference among the sites, however higher 11-KT concentrations were detected in females from sites S2 and S3. A lower proportion of perinucleolar follicles and a higher incidence of vitellogenic follicles, besides, aged oocytes and the presence of eosinophilic proteinaceous fluid in the interstitial compartment were also found in females from impacted sites. These results indicate that the urbanization and consequent release of municipal wastewater containing oestrogenic compounds in the headwater creeks are altering the levels of sex hormones and gametogenesis of A. rivularis. Further studies should be performed to determine whether oestrogenic endocrine disrupters are disrupting the reproduction of A. rivularis.

The role of kisspeptin neurons in reproduction and metabolism.

Kisspeptin is a neuropeptide with a critical role in the function of the hypothalamic-pituitary-gonadal (HPG) axis. Kisspeptin is produced by two major populations of neurons located in the hypothalamus, the rostral periventricular region of the third ventricle (RP3V) and arcuate nucleus (ARC). These neurons project to and activate gonadotrophin-releasing hormone (GnRH) neurons (acting via the kisspeptin receptor, Kiss1r) in the hypothalamus and stimulate the secretion of GnRH. Gonadal sex steroids stimulate kisspeptin neurons in the RP3V, but inhibit kisspeptin neurons in the ARC, which is the underlying mechanism for positive- and negative feedback respectively, and it is now commonly accepted that the ARC kisspeptin neurons act as the GnRH pulse generator. Due to kisspeptin's profound effect on the HPG axis, a focus of recent research has been on afferent inputs to kisspeptin neurons and one specific area of interest has been energy balance, which is thought to facilitate effects such as suppressing fertility in those with under- or severe over-nutrition. Alternatively, evidence is building for a direct role for kisspeptin in regulating energy balance and metabolism. Kiss1r-knockout (KO) mice exhibit increased adiposity and reduced energy expenditure. Although the mechanisms underlying these observations are currently unknown, Kiss1r is expressed in adipose tissue and potentially brown adipose tissue (BAT) and Kiss1rKO mice exhibit reduced energy expenditure. Recent studies are now looking at the effects of kisspeptin signalling on behaviour, with clinical evidence emerging of kisspeptin affecting sexual behaviour, further investigation of potential neuronal pathways are warranted.

Estradiol-Dependent and -Independent Stimulation of Kiss1 Expression in the Amygdala, BNST, and Lateral Septum of Mice.

Kisspeptin, encoded by Kiss1, activates reproduction by stimulating GnRH neurons. Although most Kiss1 neurons are located in the hypothalamus, smaller Kiss1 populations also reside in the medial amygdala (MeA), bed nucleus of the stria terminalis (BnST), and lateral septum (LS). However, very little is known about the regulation and function of these extra-hypothalamic Kiss1 neurons. This study focused on the roles and interactions of two signaling factors, estradiol (E2) and GABA, known to stimulate and inhibit, respectively, extra-hypothalamic Kiss1 expression. First, using estrogen receptor (ER)α knockout (KO) and βERKO mice, we demonstrated that Kiss1 in both the BnST and LS is stimulated by E2, as occurs in the MeA, and that this E2 upregulation occurs via ERα, but not ERβ. Second, using GABABR KO and wild-type mice, we determined that whereas E2 normally increases extra-hypothalamic Kiss1 levels, such upregulation by E2 is further enhanced by the concurrent absence of GABABR signaling in the MeA and LS, but not the BnST. Third, we demonstrated that when GABABR signaling is absent, the additional removal of gonadal sex steroids does not abolish Kiss1 expression in the MeA and BnST, and in some cases the LS. Thus, Kiss1 expression in these extra-hypothalamic regions is not solely dependent on E2 stimulation. Finally, we demonstrated a significant positive correlation between Kiss1 levels in the MeA, BnST, and LS, but not between these regions and the hypothalamus (anteroventral periventricular nucleus/periventricular nucleus). Collectively, our findings indicate that both E2 and GABA independently regulate all three extra-hypothalamic Kiss1 populations, but their regulatory interactions may vary by brain region and additional yet-to-be-identified factors are likely involved.

Emerging insights into hypothalamic-pituitary-gonadal axis regulation and interaction with stress signalling.

Reproduction and fertility are regulated via hormones of the hypothalamic-pituitary-gonadal (HPG) axis. Control of this reproductive axis occurs at all levels, including the brain and pituitary, and allows for the promotion or inhibition of gonadal sex steroid secretion and function. In addition to guiding proper gonadal development and function, gonadal sex steroids also act in negative- and positive-feedback loops to regulate reproductive circuitry in the brain, including kisspeptin neurones, thereby modulating overall HPG axis status. Additional regulation is also provided by sex steroids made within the brain, including neuroprogestins. Furthermore, because reproduction and survival need to be coordinated and balanced, the HPG axis is able to modulate (and be modulated by) stress hormone signalling, including cortiscosterone, from the hypothalamic-pituitary-adrenal (HPA) axis. This review covers recent data related to the neural, hormonal and stress regulation of the HPG axis and emerging interactions between the HPG and HPA axes, focusing on actions at the level of the brain and pituitary.

Neuropeptide and steroid hormone mediators of neuroendocrine regulation.

To maintain the health and well-being of all mammals, numerous aspects of physiology are controlled by neuroendocrine mechanisms. These mechanisms ultimately enable communication between neurones and glands throughout the body and are centrally mediated by neuropeptides and/or steroid hormones. A recent session at the International Workshop in Neuroendocrinology highlighted the essential roles of some of these neuropeptide and steroid hormone mediators in the neuroendocrine regulation of stress-, reproduction- and behaviour-related processes. Accordingly, the present review highlights topics presented in this session, including the role of the neuropeptides corticotrophin-releasing factor and gonadotrophin-releasing hormone in stress and reproductive physiology, respectively. Additionally, it details an important role for gonadal sex steroids in the development of behavioural sex preference.

Reproductive cycle of leopard grouper Mycteroperca rosacea (Streets, 1877) held in captivity: relation ship between gonad development and sex steroid concentration

In this study, sex steroids (E2, T, and 11-KT) concentrations in blood of captive leopard grouper ( Mycteroperca rosacea ) and their relation togonad development were determined during a reproductive cycle. Each month, gonad samples from 24 fish were obtained to analyze gonadal maturation and blood was extracted to determine steroid levels. Throughout the year, ovaries showed a higher percentageof primary oocytes. In January, oocytes at early and late vitellogenesis stages increased progressively; from March to June, ovulation rates were high. In females, estradiol levels increased from March and decreased after the spawning season. Lower levels of testosterone were found during the spawning season and 11-KT remained without significant changes throughout the year. Males exhibit a significant increase in E2 from March until July; testosterone remained without significant variation throughout theyear, and 11-KT plasma levels increased from March until July and decreased after the spawning season. In this study, we verified the sex change of an organism and the concentrations of sexual steroids were determined and discussed.

Impact of X/Y genes and sex hormones on mouse neuroanatomy

Biological sex influences brain anatomy across many species. Sex differences in brain anatomy have classically been attributed to differences in sex chromosome complement (XX versus XY) and/or in levels of gonadal sex steroids released from ovaries and testes. Using the four core genotype (4CG) mouse model in which gonadal sex and sex chromosome complement are decoupled, we previously found that sex hormones and chromosomes influence the volume of distinct brain regions. However, recent studies suggest there may be more complex interactions between hormones and chromosomes, and that circulating steroids can compensate for and/or mask underlying chromosomal effects. Moreover, the impact of pre vs post-pubertal sex hormone exposure on this sex hormone/sex chromosome interplay is not well understood. Thus, we used whole brain high-resolution ex-vivo MRI of intact and pre-pubertally gonadectomized 4CG mice to investigate two questions: 1) Do circulating steroids mask sex differences in brain anatomy driven by sex chromosome complement? And 2) What is the contribution of pre- versus post-pubertal hormones to sex-hormone-dependent differences in brain anatomy? We found evidence of both cooperative and compensatory interactions between sex chromosomes and sex hormones in several brain regions, but the interaction effects were of low magnitude. Additionally, most brain regions affected by sex hormones were sensitive to both pre- and post-pubertal hormones. This data provides further insight into the biological origins of sex differences in brain anatomy.

Protection from vascular dysfunction in female rats with chronic stress and depressive symptoms.

The increasing prevalence and severity of clinical depression are strongly correlated with vascular disease risk, creating a comorbid condition with poor outcomes but demonstrating a sexual disparity whereby female subjects are at lower risk than male subjects for subsequent cardiovascular events. To determine the potential mechanisms responsible for this protection against stress/depression-induced vasculopathy in female subjects, we exposed male, intact female, and ovariectomized (OVX) female lean Zucker rats to the unpredictable chronic mild stress (UCMS) model for 8 wk and determined depressive symptom severity, vascular reactivity in ex vivo aortic rings and middle cerebral arteries (MCA), and the profile of major metabolites regulating vascular tone. While all groups exhibited severe depressive behaviors from UCMS, severity was significantly greater in female rats than male or OVX female rats. In all groups, endothelium-dependent dilation was depressed in aortic rings and MCAs, although myogenic activation and vascular (MCA) stiffness were not impacted. Higher-resolution results from pharmacological and biochemical assays suggested that vasoactive metabolite profiles were better maintained in female rats with normal gonadal sex steroids than male or OVX female rats, despite increased depressive symptom severity (i.e., higher nitric oxide and prostacyclin and lower H2O2 and thromboxane A2 levels). These results suggest that female rats exhibit more severe depressive behaviors with UCMS but are partially protected from the vasculopathy that afflicts male rats and female rats lacking normal sex hormone profiles. Determining how female sex hormones afford partial vascular protection from chronic stress and depression is a necessary step for addressing the burden of these conditions on cardiovascular health. NEW & NOTEWORTHY This study used a translationally relevant model for chronic stress and elevated depressive symptoms to determine how these factors impact conduit and resistance arteriolar function in otherwise healthy rats. While chronic stress leads to an impaired vascular reactivity associated with elevated oxidant stress, inflammation, and reduced metabolite levels, we demonstrated partial protection from vascular dysfunction in female rats with normal sex hormone profiles compared with male or ovariectomized female rats.

Sex steroid production associated with puberty is absent in germ cell-free salmon

In all vertebrates studied so far, germ cells are not required for pubertal maturation of the gonadal steroidogenic system, subsequent development of secondary sex characteristics and reproductive behavior. To explore if the absence of germ cells affects puberty or growth in Atlantic salmon, germ cell-free (GCF), dnd knockout and wild type (WT) postsmolts were stimulated to enter puberty. No GCF fish entered puberty, whereas 66.7% (males) and 30% (females) WT fish completed or entered puberty, respectively. Expression of genes related to steroidogenesis (star, cyp17a1, cyp11β, cyp19a1a), gonadal somatic cells (insl3, amh, igf3), oocytes (bmp15), gonadotropin receptors (fshr, lhcgr), and pituitary gonadotropic cells (fshb, lhb, gnrhr4) showed an immature status and failure to up-regulate gonadal sex steroid production in male and female GCF fish was also reflected in low or undetectable plasma sex steroids (11-ketotestosterone, estradiol-17β and testosterone). A gender difference (high in females, low in males) was found in the expression of star and cyp17a1 in GCF fish. No clear difference in growth was detected between GCF and immature WT fish, while growth was compromised in maturing WT males. We demonstrate for the first time in a vertebrate that germ cells are required for pubertal activation of the somatic steroidogenic cells.

Metabolism and Energy Expenditure, But Not Feeding or Glucose Tolerance, Are Impaired in Young Kiss1r KO Female Mice.

Kisspeptin regulates reproduction via signaling through the receptor, Kiss1r, in GnRH neurons. However, both kisspeptin and Kiss1r are produced in several peripheral tissues, and recent studies have highlighted a role for kisspeptin signaling in metabolism and glucose homeostasis. We recently reported that Kiss1r knockout (KO) mice display a sexually dimorphic metabolic phenotype, with KO females displaying obesity, impaired metabolism, and glucose intolerance at 4-5 months of age. However, it remains unclear when this metabolic phenotype first emerges in development, or which aspects of the pleiotropic phenotype underlie the metabolic defects and which are secondary to the obesity. Here, we studied Kiss1r KO females at different ages, including several weeks before the emergence of body weight (BW) differences and later when obesity is present. We determined that at young adult ages (6 wk old), KO females already exhibit altered adiposity, leptin levels, metabolism, and energy expenditure, despite having normal BWs at this time. In contrast, food intake, water intake, and glucose tolerance are normal at young ages and only show impairments at older adult ages, suggesting that these impairments may be secondary to earlier alterations in metabolism and adiposity. We also demonstrate that, in addition to BW, all other facets of the adult metabolic phenotype persist even when gonadal sex steroids are similar between genotypes. Collectively, these data highlight the developmental emergence of a metabolic phenotype induced by disrupted kisspeptin signaling and reveal that multiple, but not all, aspects of this phenotype are already disrupted before detectable changes in BW.

Sex and Gender Differences in Central Nervous System-Related Disorders.

There are important sex differences in the brain that seem to arise from biology as well as psychosocial influences. Sex differences in several aspects of human behavior and cognition have been reported. Gonadal sex steroids or genes found on sex chromosomes influence sex differences in neuroanatomy, neurochemistry and neuronal structure, and connectivity. There has been some resistance to accept that sex differences in the human brain exist and have biological relevance; however, a few years ago, it has been recommended by the USA National Institute of Mental Health to incorporate sex as a variable in experimental and clinical neurological and psychiatric studies. We here review the clinical literature on sex differences in pain and neurological and psychiatric diseases, with the aim to further stimulate interest in sexual dimorphisms in the brain and brain diseases, possibly encouraging more research in the field of the implications of sex differences for treating these conditions.

Role of the planar cell polarity pathway in regulating ectopic hair cell-like cells induced by Math1 and testosterone treatment

Planar cell polarity (PCP) signaling regulates cochlear extension and coordinates orientation of sensory hair cells in the inner ear. Retroviral-mediated introduction of the Math1 transcription factor leads to the transdifferentiation of some mature supporting cells into hair cells. Testosterone, a gonadal sex steroid hormone, is associated with neuroprotection and regeneration in Central Nervous System (CNS) development. Experiments were performed in vitro using Ad5-EGFP-Math1/Ad5-Math1 in neonatal mouse cochleas. Establishment of ectopic hair-cell like cell(HCLC) polarity in the lesser epithelial ridge (LER) with or without testosterone-3-(O-carboxymethyl) oxime bovine serum albumin (testosterone-BSA) treatment was investigated to determine the role of the PCP pathway in regulating ectopic regenerated (HCLCs) through induction by Math1 and testosterone treatment. After Math1 infection, new ectopic regenerated HCLCs were detected in the LER. After the HCLCs developed actin-rich stereocilia, the basal bodies moved from the center to the distal side. Moreover, the narrower, non-sensory LER region meant that the convergent extension (CE) was also established after transfection with Math1. After 9 days of in vitro testosterone-BSA treatment, more Edu(+), Sox2(+), and HCLC cells were observed in the LER with an accompanying downregulation of E-cadherin. Interestingly, the CE of the Ad5-EGFP-math1 treated LER is altered, but the intrinsic cellular polarity of the HCLCs is not obviously changed. In summary, our results indicate that PCP signaling is involved in the development of ectopic HCLCs and the CE of the ectopic sensory region is altered by testosterone-BSA through downregulation of cell–cell adhesion. Testosterone-BSA and Math1 treatment could promote an increase in HCLCs in the LER through proliferation and transdifferentiation.