Roles of steroid hormones and their receptors in structural organization in the nervous system

The role of nitric oxide and neuroendocrine system in pain generation

Previous studies have indicated a complex interplay between the nitric oxide (NO) pain signaling pathways and hormonal signaling pathways in the body. This article delineates the role of nitric oxide signaling in neuropathic and inflammatory pain generation and subsequently discusses how the neuroendocrine system is involved in pain generation. Hormonal systems including the hypothalamic-pituitary axis (HPA) generation of cortisol, the renin-angiotensin-aldosterone system, calcitonin, melatonin, and sex hormones could potentially contribute to the generation of nitric oxide involved in the sensation of pain. Further research is necessary to clarify this relationship and may reveal therapeutic targets involving NO signaling that alleviate neuropathic and inflammatory pain.

The association of caffeine and nandrolone decanoate modulates aversive memory and nociception in rats

Caffeine and anabolic-androgenic steroids (AAS) are commonly used to improve muscle mass and athletic performance. Nandrolone Decanoate (ND) is one of the most abused AAS worldwide, leading to behavioral changes in both humans and rodents. Caffeine, the most widely consumed psychostimulant globally, is present in various thermogenic and gym supplements. Low and moderate doses of caffeine antagonize adenosine receptors and have been linked to improved memory and pain relief. We have previously demonstrated that consuming caffeine prevents the risk-taking behavior triggered by nandrolone. In this study, we aimed to investigate the long-term effects of ND and caffeine, either alone or in combination, on passive avoidance memory and nociception. We used the step-down and hot-plate tasks in male and female Lister Hooded rats. Our results confirmed the antinociceptive effect of caffeine and indicated that chronic administration of the ND-caffeine association promotes the evocation of aversive memory in female rats.

Fetal endocrine axes mRNA expression levels are related to sex and intrauterine position

BACKGROUND

The hypothalamic-pituitary-adrenal (HPA) and -gonadal (HPG) axes are two major pathways that connect the neural and endocrine systems in vertebrates. Factors such as prenatal stress and maternal exposure to exogenous steroids have been shown to affect these pathways during fetal development. Another less studied factor is the transfer of hormones across fetuses in multifetal pregnancies. This form of transfer has been shown to influence the morphology, anatomy, physiology, and behavior of the offspring in litter-bearing mammals, an influence termed the intrauterine position (IUP) effect. In this study, we sought to delineate how the IUP effects HPA and HPG brain receptors, peptides, and enzymes (hereafter components) in utero and how these influences may differ between males and females.

METHODS

We utilized the unconventional model of culled free-ranging nutria (Myocastor coypus), with its large natural variation. We collected brain tissues from nutria fetuses and quantified the expression of key HPA and HPG components in three brain regions: prefrontal cortex, hypothalamus, and striatum.

RESULTS

We found an interaction between sex and IUP in the mineralocorticoid receptor (MR), gonadotropin-releasing hormone receptor (GNRHR), androgen receptor (AR), and estrogen receptor alpha (ESR1). IUP was significant in both gonadotropin-releasing hormone (GnRH) and its receptor GNRHR, but in different ways. In the hypothalamus, fetuses adjacent to same-sex neighbors had higher expression of GnRH than fetuses neighboring the opposite sex. Conversely, in the cortex, GNRHR exhibited the inverse pattern, and fetuses that were neighboring the opposite sex had higher expression levels than those neighboring the same sex. Regardless of IUP, in most components that showed significant sex differences, female fetuses had higher mRNA expression levels than male fetuses. We also found that HPA and HPG components were highly related in the early stages of gestation, and that there was an interaction between sex and developmental stage. In the early stages of pregnancy, female component expression levels were more correlated than males', but in the last trimester of pregnancy, male components were more related to each other than female's.

CONCLUSIONS

This study suggests that there are sexually different mechanisms to regulate the HPA and HPG axes during fetal development. Higher mRNA expression levels of endocrine axes components may be a mechanism to help females cope with prolonged androgen exposure over a long gestational period. Additionally, these findings suggest different coordination requirements of male and female endocrine axes during stages of fetal development.

Pain mechanisms in the transgender individual: a review

Specific Aim

Provide an overview of the literature addressing major areas pertinent to pain in transgender persons and to identify areas of primary relevance for future research.

Methods

A team of scholars that have previously published on different areas of related research met periodically though zoom conferencing between April 2021 and February 2023 to discuss relevant literature with the goal of providing an overview on the incidence, phenotype, and mechanisms of pain in transgender patients. Review sections were written after gathering information from systematic literature searches of published or publicly available electronic literature to be compiled for publication as part of a topical series on gender and pain in the Frontiers in Pain Research.

Results

While transgender individuals represent a significant and increasingly visible component of the population, many researchers and clinicians are not well informed about the diversity in gender identity, physiology, hormonal status, and gender-affirming medical procedures utilized by transgender and other gender diverse patients. Transgender and cisgender people present with many of the same medical concerns, but research and treatment of these medical needs must reflect an appreciation of how differences in sex, gender, gender-affirming medical procedures, and minoritized status impact pain.

Conclusions

While significant advances have occurred in our appreciation of pain, the review indicates the need to support more targeted research on treatment and prevention of pain in transgender individuals. This is particularly relevant both for gender-affirming medical interventions and related medical care. Of particular importance is the need for large long-term follow-up studies to ascertain best practices for such procedures. A multi-disciplinary approach with personalized interventions is of particular importance to move forward.

Histological analysis of neuronal changes in the olfactory cortex during pregnancy

Fluctuations in olfactory sensitivity are widely known to occur during pregnancy and may be responsible for hyperemesis gravidarum. These changes are thought to be caused by structural and functional alterations in neurons in response to marked changes of the hormonal milieu. In this study, we examined changes in neurons in the olfactory cortex during pregnancy and after delivery in rats. Dendritic spine densities were measured in the piriform cortex (PIR) and posterolateral cortical amygdala (COApl), which are involved in olfaction. The results showed increased numbers of dendritic spines in the PIR in mid-pregnancy and in the COApl during early and late pregnancy, but not in the motor area of the cerebral cortex, indicating a correlation with changes in olfactory sensitivity during pregnancy. Immunohistochemical analysis of expression of ovarian hormone receptors in these brain regions revealed a decrease in the number of estrogen receptor α-positive cells during pregnancy in the PIR and during pregnancy and the postpartum period in the COApl. Regarding pregnancy-related peptide hormones, oxytocin receptors were expressed in the PIR and COApl, while prolactin receptors were not found in these regions. Accordingly, oxytocin-containing neurites were distributed in both regions. These results suggest that the balance of these hormonal signals has an effect on olfactory sensitivity in pregnant females.

Sex and Brain: The Role of Sex Chromosomes and Hormones in Brain Development and Parkinson's Disease

Sex hormones and genes on the sex chromosomes are not only key factors in the regulation of sexual differentiation and reproduction but they are also deeply involved in brain homeostasis. Their action is crucial for the development of the brain, which presents different characteristics depending on the sex of individuals. The role of these players in the brain is fundamental in the maintenance of brain function during adulthood as well, thus being important also with respect to age-related neurodegenerative diseases. In this review, we explore the role of biological sex in the development of the brain and analyze its impact on the predisposition toward and the progression of neurodegenerative diseases. In particular, we focus on Parkinson's disease, a neurodegenerative disorder that has a higher incidence in the male population. We report how sex hormones and genes encoded by the sex chromosomes could protect from the disease or alternatively predispose toward its development. We finally underline the importance of considering sex when studying brain physiology and pathology in cellular and animal models in order to better understand disease etiology and develop novel tailored therapeutic strategies.

Piezo1 regulates cholesterol biosynthesis to influence neural stem cell fate during brain development

Mechanical forces and tissue mechanics influence the morphology of the developing brain, but the underlying molecular mechanisms have been elusive. Here, we examine the role of mechanotransduction in brain development by focusing on Piezo1, a mechanically activated ion channel. We find that Piezo1 deletion results in a thinner neuroepithelial layer, disrupts pseudostratification, and reduces neurogenesis in E10.5 mouse embryos. Proliferation and differentiation of Piezo1 knockout (KO) mouse neural stem cells (NSCs) isolated from E10.5 embryos are reduced in vitro compared to littermate WT NSCs. Transcriptome analysis of E10.5 Piezo1 KO brains reveals downregulation of the cholesterol biosynthesis superpathway, in which 16 genes, including Hmgcr, the gene encoding the rate-limiting enzyme of the cholesterol biosynthesis pathway, are downregulated by 1.5-fold or more. Consistent with this finding, membrane lipid composition is altered, and the cholesterol levels are reduced in Piezo1 KO NSCs. Cholesterol supplementation of Piezo1 KO NSCs partially rescues the phenotype in vitro. These findings demonstrate a role for Piezo1 in the neurodevelopmental process that modulates the quantity, quality, and organization of cells by influencing cellular cholesterol metabolism. Our study establishes a direct link in NSCs between PIEZO1, intracellular cholesterol levels, and neural development.

Differential effects of steroid hormones on levels of broad-sense heritability in a wild bird: possible mechanism of environment × genetic variance interaction?

Genetic variation is one of the key concepts in evolutionary biology and an important prerequisite of evolutionary change. However, we know very little about processes that modulate its levels in wild populations. In particular, we still are to understand why genetic variances often depend on environmental conditions. One of possible environment-sensitive modulators of observed levels of genetic variance are maternal effects. In this study we attempt to experimentally test the hypothesis that maternally transmitted agents (e.g. hormones) may influence the expression of genetic variance in quantitative traits in the offspring. We manipulated the levels of steroid hormones (testosterone and corticosterone) in eggs laid by blue tits in a wild population. Our experimental setup allowed for full crossing of genetic and rearing effects with the experimental manipulation. We observed that birds treated with corticosterone exhibited a significant decrease in broad-sense genetic variance of tarsus length, and an increase in this component in body mass on the 2nd day post-hatching. Our study indicates, that maternally transmitted substances such as hormones may have measurable impact on the levels of genetic variance and hence, on the evolutionary potential of quantitative traits.

Molecular dynamics of estrogen-related receptors and their regulatory proteins: roles in transcriptional control for endocrine and metabolic signaling

Estrogen-related receptor (ERR) is a member of the nuclear receptor (NR) superfamily and has three subtypes α, β, and γ. Despite their strong homology with estrogen receptor (ER) α, ERRs cannot accommodate endogenous hormones. However, they are able to regulate gene expression without ligand binding. ERRα and ERRγ orchestrate the expression of genes involved in bioenergetic pathways, while ERRβ controls placental development and stem cell maintenance. Evidence from recent studies, including clinical research, has also demonstrated close associations of ERRs with the pathophysiology of hormone-related cancers and metabolic disorders including type 2 diabetes mellitus. This review summarizes the basic knowledge and recent advances in ERRs and their associated proteins, focusing on the subcellular dynamics involved in transcriptional regulation. Fluorescent protein labeling enabled monitoring of ERRs in living cells and revealed previously unrecognized characteristics. Using this technique, we demonstrated a role of ERRβ in controlling estrogen signaling by regulating the subnuclear dynamics of ligand-activated ERα. Visualization of ERRs and related proteins and subsequent analyses also revealed a function of ERRγ in promoting liver lactate metabolism in association with LRPGC1, a recently identified lactic acid-responsive protein. These findings suggest that ERRs activate unique transregulation mechanisms in response to extracellular stimuli such as hormones and metabolic signals, implying an adaptive system behind the cellular homeostatic regulation by orphan NRs. Control of subcellular ERR dynamics will contribute toward the development of therapeutic approaches to treat various diseases including hormone-related cancers and metabolic disorders associated with abnormal ERR signaling pathways.

Clinical Significance of Intraoperative Exposure of Inferior Alveolar Nerve during Surgical Extraction of the Mandibular Third Molar in Nerve Injury

During extraction surgery, the inferior alveolar nerve (IAN) can occasionally be observed in the extraction socket of the mandibular third molar (M3). The purpose of this study was to investigate and compare the incidence of IAN injury in groups with and without intraoperative IAN exposure during surgical extraction of M3, and to identify additional risk factors for the IAN injury in addition to the IAN exposure. A total of 288 cases in 240 patients, who underwent surgical extraction of M3 by a single surgeon, were divided into the exposed group (n = 69) and the unexposed group (n = 219). The surgeon recorded the information regarding the procedure when the clinical observation of IAN exposure was made during the surgery. The incidence of IAN injury after the extraction surgery was significantly higher in the exposed group than in the unexposed group (4.3% versus 0%, p < 0.05). Paresthesia was recognized in three cases of the exposed group, but it showed complete recovery within three postoperative months. No case of permanent paresthesia was detected in both groups. According to the logistic regression, the only significant risk factor of IAN injury in the exposed group was the increase of age (OR 1.108, p < 0.05). Intraoperative IAN exposure during surgical extraction of M3 may show a higher incidence of IAN injury than the case without IAN exposure, representing an incidence of 4.3%. Even if the paresthesia associated with IAN exposure occurs, it is likely to be a temporary injury, and this risk may increase with age.

The Effect of Castration on Peripheral Autonomic Neurons Supplying Mammalian Male Genitourinary System

This review paper deals with the influence of androgens (testosterone) on pelvic autonomic pathways in male mammals. The vast majority of the relevant information has been gained in experiments involving castration (testosterone deprivation) performed in male rats, and recently, in male pigs. In both species, testosterone significantly affects the biology of the pathway components, including the pelvic neurons. However, there are great differences between rats and pigs in this respect. The most significant alteration is that testosterone deprivation accomplished a few days after birth results some months later in the excessive loss (approximately 90%) of pelvic and urinary bladder trigone intramural neurons in the male pig, while no changes in the number of pelvic neurons are observed in male rats (rats do not have the intramural ganglia). In the castrated pigs, much greater numbers of pelvic neurons than in the non-castrated animals express CGRP, GAL, VIP (peptides known to have neuroprotective properties), and caspase 3, suggesting that neurons die due to apoptosis triggered by androgen deprivation. In contrast, only some morpho-electrophysiological changes affecting neurons following castration are found in male rats. Certain clinicopathological consequences of testosterone deprivation for the functioning of urogenital organs are also discussed.

Sirt7-p21 Signaling Pathway Mediates Glucocorticoid-Induced Inhibition of Mouse Neural Stem Cell Proliferation

Prenatal glucocorticoid (GC) overexposure impacts fetal hippocampal neural stem cells (NSCs) and increases the risk for relative cognitive and mood disorders in offspring. However, the precise underlying mechanisms remain elusive. Here, we treated mouse hippocampal NSCs with dexamethasone (DEX) in vitro and found that DEX inhibited cell proliferation and Sirt7 expression. In addition, prenatal mouse overexposure to DEX induced the suppression of Sirt7 in the hippocampus of offspring. Sirt7 knockdown significantly decreased the percentage of proliferating cells but did not further reduce the NSC proliferation rate in the presence of DEX, whereas Sirt7 overexpression rescued DEX-induced inhibition of hippocampal NSC proliferation. Moreover, DEX inhibited Sirt7 expression through the glucocorticoid receptor (GR), and p21 was found to mediate the functional effect of DEX-induced Sirt7 suppression. In conclusion, our data demonstrate for the first time the effect of DEX on the Sirt7-p21 pathway in hippocampal NSCs, identifying a new potential therapeutic target for prenatal GC overexposure-related neurodevelopmental disorders in offspring.

[Radiosurgical hypophysectomy in cancer pain treatment. Literature review and clinical case]

Cancer pain is one of the main problem in modern medicine. According European Society for Medical Oncology data, cancer pain prevalence is 64% among patient with terminal stage of disease and in 46% standard pain therapy was ineffective. Radiosurgical hypophysectomy is one of the important and perspective method in cancer pain treatment. This method could be offered patient with chronic disease. According literature review, endocrinology complications were very rare and occurred 10 months after therapy. Value of analgesic effect was 70-90%. In some trials, procedure was effective not only nociceptive, but also in neuropathic pain. More trials require for determination of indications and mechanism of action. The case of successful relief of resistant pain in patient with pancreatic cancer by means of radiosurgical hypophysectomy is described.

Influences of age and pubertal status on number and intensity of perineuronal nets in the rat medial prefrontal cortex

The prefrontal cortex (PFC) is a late developing region of the cortex, and its protracted maturation during adolescence may confer a period of plasticity. Closure of critical, or sensitive, periods in sensory cortices coincides with perineuronal net (PNN) expression, leading to enhanced inhibitory function and synaptic stabilization. PNN density has been found to increase across adolescence in the male rat medial PFC (mPFC). Here, we examined both male and female rats at four time points spanning adolescent development to stereologically quantify the number and intensity of PNNs in the mPFC. Additionally, because puberty coincides with broad behavioral and neuroanatomical changes, we collected tissue from age-matched pre- and post-pubertal siblings within a litter. Results indicate that both males and females show an increase in the total number and intensity of mPFC PNNs between postnatal day (P) 30 and P60. As we have previously found, white matter under the mPFC also increased at the same time. Male puberty did not affect PNNs, while female pubertal onset led to an abrupt decrease in the total number of PNNs that persisted through mid-adolescence before increasing at P60. Despite the change in PNN number, the intensity of female PNNs was not affected by puberty. Thus, though males and females show increases in mPFC PNNs during adolescence, the pubertal decrease in the number of PNNs in female rats may indicate a difference in the pattern of maximal plasticity between the sexes during adolescence.

Model-robust designs for nonlinear quantile regression

We construct robust designs for nonlinear quantile regression, in the presence of both a possibly misspecified nonlinear quantile function and heteroscedasticity of an unknown form. The asymptotic mean-squared error of the quantile estimate is evaluated and maximized over a neighbourhood of the fitted quantile regression model. This maximum depends on the scale function and on the design. We entertain two methods to find designs that minimize the maximum loss. The first is local - we minimize for given values of the parameters and the scale function, using a sequential approach, whereby each new design point minimizes the subsequent loss, given the current design. The second is adaptive - at each stage, the maximized loss is evaluated at quantile estimates of the parameters, and a kernel estimate of scale, and then the next design point is obtained as in the sequential method. In the context of a Michaelis-Menten response model for an estrogen/hormone study, and a variety of scale functions, we demonstrate that the adaptive approach performs as well, in large study sizes, as if the parameter values and scale function were known beforehand and the sequential method applied. When the sequential method uses an incorrectly specified scale function, the adaptive method yields an, often substantial, improvement. The performance of the adaptive designs for smaller study sizes is assessed and seen to still be very favourable, especially so since the prior information required to design sequentially is rarely available.

Transcranial Direct Current Stimulation at 4 mA Induces Greater Leg Muscle Fatigability in Women Compared to Men

Transcranial direct current stimulation (tDCS) has previously shown different cortical excitability and neuropsychological effects between women and men. However, the sex-specific effects of tDCS on leg muscle fatigability has not been investigated. The purpose of this study was to determine the effects of a single session of 2 mA and 4 mA primary motor cortex tDCS on leg muscle fatigability in healthy young men and women in a crossover design. Twenty participants (women = 10) completed isokinetic fatigue testing (40 maximal reps, 120°/s) of the knee extensors and flexors in conjunction with sham, 2 mA, and 4 mA tDCS in a double-blind, randomized design. The fatigue index from each condition was calculated. Women had significantly greater knee extensor fatigability in the 4 mA condition compared to men (57.8 ± 6.8% versus 44.1 ± 18.4%; p = 0.041, d = 0.99). This study provides additional evidence that responses to tDCS may be sex-specific and highlights the necessity of accounting and powering for sex differences in future investigations.

Scaffold attachment factor B: distribution and interaction with ERα in the rat brain

Scaffold attachment factor (SAFB) 1 and its homologue SAFB2 are multifunctional proteins that are involved in various cellular mechanisms, including chromatin organization and transcriptional regulation, and are also corepressors of estrogen receptor alpha (ERα). Both SAFBs are expressed at high levels in the brain. However, the distributions of SAFB1 and SAFB2 have yet to be characterized in detail and it is unclear whether both proteins interact with ERα in the brain. In this study, we investigated the expression and distribution of both SAFBs and their interaction with ERα in adult male rat brain. Immunohistochemical staining showed that SAFB1 and SAFB2 have a similar distribution pattern and are widely expressed throughout the brain. Double-fluorescence immunohistochemical and immunocytochemical analyses in primary cultures showed that the two SAFB proteins are localized in nuclei of neurons, astrocytes, and oligodendrocytes. Of note, SAFB2 was also found in cytoplasmic regions in these cell lineages. Both SAFB proteins were also expressed in ERα-positive cells in the medial preoptic area (MPOA) and arcuate and ventromedial hypothalamic nuclei. Co-immunoprecipitation experiments revealed that both SAFB proteins from the MPOA reciprocally interact with endogenous ERα. These results indicate that, in addition to a role in basal cellular function in the brain, the SAFB proteins may serve as ERα corepressors in hormone-sensitive regions.

Understanding the Role of Puberty in Structural and Functional Development of the Adolescent Brain

Over the past two decades, there has been a tremendous increase in our understanding of structural and functional brain development in adolescence. However, understanding the role of puberty in this process has received much less attention. This review examines this relationship by summarizing recent research studies where the role of puberty was investigated in relation to brain structure, connectivity, and task-related functional magnetic resonance imaging (fMRI). The studies together suggest that puberty may contribute to adolescent neural reorganization and maturational advancement, and sex differences also emerge in puberty. The current body of work shows some mixed results regarding impact and exact direction of pubertal influence. We discuss several limitations of current studies and propose future directions on how to move the field forward.

Determination of testosterone and corticosterone in feathers using liquid chromatography-mass spectrometry

Feathers gradually accumulate hormones and reflect long-term average plasma steroid levels during their growth. Feather hormone levels thus provide for the measurement of plasma hormones concentrations integrated over a period of several days or weeks. In this study, we focused on the development of a method to determine testosterone (TEST) and corticosterone (CORT) levels in extracts from feathers of small bodied birds with a limited amount of feathers available per individual. For this purpose, the method had to be verified for a small weight of samples. The present study describes the effect of the conditions of sample preparation and keto-derivatisation on the sensitivity of the LC-ESI-MS/MS analysis of TEST and CORT. Generally, chemical derivatization improves the sensitivity and selectivity of LC-MS/MS analysis. It can be used particularly in situations when the total amount of collected sample is limited (such as in our studies). Both the conditions of feather sample preparation (the selection of the extraction solvent, the time of extraction, and the conditions of solid phase extraction) and the reaction conditions affecting the formation of keto-derivatives (such as reaction temperature and reaction time) were tested. Methanol as the extraction solvent, 8 h as the extraction time, 50 °C as the reaction temperature of derivatization, and 90 min as the reaction time of derivatization are the most suitable conditions in terms of achieving a high sensitivity of analyses. Calibration curves are linear, at least in the range 25-2500 pg mL^-1, which is usually found in feather extracts. The limit of detection (LOD) for TEST and CORT was 1.0 and 0.3 pg per mL, respectively. The limit of quantification (LOQ) for TEST and CORT was 3.3 and 1.0 pg per mL, respectively. The optimized procedure was successfully applied for the analysis of TEST and CORT in real feather samples. The method could be used in a variety of research direction including wildlife, agricultural or veterinary studies.

Intranuclear Mobility of Estrogen Receptor: Implication for Transcriptional Regulation

The estrogen receptor (ER) is a ligand-dependent transcription factor that has two subtypes: ERα and ERβ. ERs regulate transcription of estrogen-responsive genes through interactions with multiple intranuclear components, such as cofactors and the nuclear matrix. Live cell imaging using fluorescent protein-labeled ERs has revealed that ligand-activated ERs are highly mobile in the nucleus, with transient association with the DNA and nuclear matrix. Scaffold attachment factor B (SAFB) 1 and its paralogue, SAFB2, are nuclear matrix-binding proteins that negatively modulate ERα-mediated transcription. Expression of SAFB1 and SAFB2 reduces the mobility of ERα in the presence of ligand. This regulatory machinery is emerging as an epigenetic-like mechanism that alters transcriptional activity through control of intranuclear molecular mobility.

Neuronal activity in the sagittalis nucleus of the hypothalamus after ovarian steroid hormone manipulation and sexual behavior in female rat

During extended observation of estrogen receptor (ER) α-immunoreactive neurons in the hypothalamus, we previously identified a novel nucleus, the Sagittalis Nucleus of the Hypothalamus (SGN), in the interstitial area between the arcuate nucleus and the ventromedial hypothalamic nucleus. The SGN exhibits sexual dimorphism in its volume and cell count, and estrous cycle related variations in ERα-immunoreactivity. These characteristics of the SGN implicate the nucleus in sex-biased brain functions and behaviors. In this study, we examined involvement of the SGN in sexual arousal in female rats. Immunohistochemical staining of c-Fos, a marker of neuronal activity was performed after administration of an estrus-inducing dose of estrogen and progesterone in ovariectomized female rats. Analysis of microscopic images showed a significant increase in the number of c-Fos-expressing neurons in the SGN following hormonal manipulation. Moreover, neuronal activity in the region exhibited a further increase after each animal was coupled with a male and allowed to mate. These results suggest that the SGN plays an important role in sexual activity in female rat.

Effects of Sex Steroids on the Spinal Gastrin-Releasing Peptide System Controlling Male Sexual Function in Rats

The gastrin-releasing peptide (GRP) system in the lumbosacral spinal cord controls male sexual function in rats. In contrast, in female rats, GRP neurons could scarcely be detected around puberty when circulating ovarian steroid hormones such as estradiol and progesterone levels are increasing. However, little information is available on feminizing or demasculinizing effects of ovarian steroids on the central nervous system in female puberty and adulthood. In this study, to visualize the spinal GRP neurons in vivo, we generated a GRP-promoter-Venus transgenic (Tg) rat line and studied the effects of the sex steroid hormones on GRP expression in the rat lumbar cord by examining the Venus fluorescence. In these Tg rats, the sexually dimorphic spinal GRP neurons controlling male sexual function were clearly labeled with Venus fluorescence. As expected, Venus fluorescence in the male lumbar cord was markedly decreased after castration and restored by chronic androgen replacement. Furthermore, androgen-induced Venus expression in the spinal cord of adult Tg males was significantly attenuated by chronic treatment with progesterone but not with estradiol. A luciferase assay using a human GRP-promoter construct showed that androgens enhance the spinal GRP system, and more strikingly, that progesterone acts to inhibit the GRP system via an androgen receptor-mediated mechanism. These results demonstrate that circulating androgens may play an important role in the spinal GRP system controlling male sexual function not only in rats but also in humans and that progesterone could be an important feminizing factor in the spinal GRP system in females during pubertal development.

Accumulation of steroid hormones in the eggshells of Japanese quail (Coturnix coturnix japonica)

Oviparous mother transfer significant amounts of steroid to egg yolk during oviposition and the amounts may vary throughout the embryonic development. Eggshell may contain steroid hormones and the amounts could be different during embryonic development inside the egg. This study was designed to quantify the steroid concentrations in the eggshells of Japanese quail. We hypothesized that the steroids would be accumulated in the eggshells in a sex-dependent manner. Eggshells were obtained from three different stages (after laying, 15 days of incubation, and after hatching). The internal contents of the shells were carefully removed, completely dried and pulverized. The steroid contents of the eggshells were then measured by RIA. Physiologic variations in steroids were analyzed according to the amounts accumulated in the eggshells with the different embryonic stages. Results indicate that eggshell testosterone concentrations were high after laying. However, the concentrations were decreased during embryonic development and hatching and no difference was found in eggshell testosterone levels between male and female. However, eggshell estradiol concentrations were undetectable at laying time and the amounts were significantly increased at 15 days of incubation and slightly after hatching. Eggshell estradiol levels were significantly high in female eggshells than male during embryonic development. In contrast, eggshell corticosterone levels were significantly higher in males than in females after hatching. These results clearly demonstrated that eggshells accumulated steroid hormones, and the amounts varied during embryonic development concomitant with changes the internal contents of the eggs.

Prenatal stress-immune programming of sex differences in comorbidity of depression and obesity/metabolic syndrome

Major depressive disorder (MDD) is the number one cause of disability worldwide and is comorbid with many chronic diseases, including obesity/metabolic syndrome (MetS). Women have twice as much risk for MDD and comorbidity with obesity/MetS as men, although pathways for understanding this association remain unclear. On the basis of clinical and preclinical studies, we argue that prenatal maternal stress (ie, excess glucocorticoid expression and associated immune responses) that occurs during the sexual differentiation of the fetal brain has sex-dependent effects on brain development within highly sexually dimorphic regions that regulate mood, stress, metabolic function, the autonomic nervous system, and the vasculature. Furthermore, these effects have lifelong consequences for shared sex-dependent risk of MDD and obesity/MetS. Thus, we propose that there are shared biologic substrates at the anatomical, molecular, and/or genetic levels that produce the comorbid risk for MDD-MetS through sex-dependent fetal origins.

Immunohistochemical profiling of estrogen-related receptor gamma in rat brain and colocalization with estrogen receptor alpha in the preoptic area

Estrogen-related receptor (ERR) is a member of the nuclear receptor superfamily that has strong homology with estrogen receptor (ER) α. Despite the lack of endogenous ligands, ERR serves as transcription factors through their constitutively active structure with or without interaction with ERα. Among the three subtypes of ERR (α, β, and γ), ERRγ is highly expressed in brain, but the distribution of ERRγ is poorly characterized. Therefore, we investigated ERRγ immunoreactivity throughout the rostro-caudal axis in rat brain. Immunohistochemistry revealed localization of ERRγ protein in the cell nucleus, and a ubiquitous distribution of ERRγ in brain regions including the olfactory bulb, cerebrum, brain stem, and cerebellum. Selective intense immunoreactivity was observed in the reticular thalamic nucleus, zona incerta, circular nucleus, interpeduncular nucleus, pontine nucleus, and parasolitary nucleus. Most ERRγ-immunoreactive (ir) regions were also positive for ERα and/or ERβ, which suggests that ERRγ is involved in modulation of estrogen signaling in adult rat brain. Double immunofluorescence demonstrated colocalization of ERRγ with ERα within the anteroventral periventricular nucleus of the preoptic area (AVPV) and medial preoptic nucleus (MPO), which are major target sites for estrogen action. The results of this study suggest that ERRγ function in the brain is affected by estrogens through an interaction with ERα. The findings also provide basic information on brain region-specific ERRγ function.

Effect of Estradiol on Neurotrophin Receptors in Basal Forebrain Cholinergic Neurons: Relevance for Alzheimer's Disease

The basal forebrain is home to the largest population of cholinergic neurons in the brain. These neurons are involved in a number of cognitive functions including attention, learning and memory. Basal forebrain cholinergic neurons (BFCNs) are particularly vulnerable in a number of neurological diseases with the most notable being Alzheimer's disease, with evidence for a link between decreasing cholinergic markers and the degree of cognitive impairment. The neurotrophin growth factor system is present on these BFCNs and has been shown to promote survival and differentiation on these neurons. Clinical and animal model studies have demonstrated the neuroprotective effects of 17β-estradiol (E2) on neurodegeneration in BFCNs. It is believed that E2 interacts with neurotrophin signaling on cholinergic neurons to mediate these beneficial effects. Evidence presented in our recent study confirms that altering the levels of circulating E2 levels via ovariectomy and E2 replacement significantly affects the expression of the neurotrophin receptors on BFCN. However, we also showed that E2 differentially regulates neurotrophin receptor expression on BFCNs with effects depending on neurotrophin receptor type and neuroanatomical location. In this review, we aim to survey the current literature to understand the influence of E2 on the neurotrophin system, and the receptors and signaling pathways it mediates on BFCN. In addition, we summarize the physiological and pathophysiological significance of E2 actions on the neurotrophin system in BFCN, especially focusing on changes related to Alzheimer's disease.

Age at menarche and risk of developing migraine or non-migraine headaches by young adulthood: A prospective cohort study

Importance

Migraine is a highly prevalent and disabling primary headache disorder that is two to three times more prevalent in young women. Among females, there is a steep increase in incidence from puberty to young adulthood, but the mechanisms for the increase are unknown.

Objective

To determine if age of menarche is a risk factor for developing migraine headache vs. non-migraine headache by young adulthood.

Design

A prospective cohort study, The Growing Up Today Study (GUTS), of adolescents who have been followed since 1996, when they were nine, to 14 years of age. Headache questions were included on the 2007 and 2010 surveys.

Setting

Youth from across the United States who are offspring of women participating in the Nurses’ Health Study II.

Participants

6112 female participants who had provided data on headache symptoms, age at menarche and family history of migraine and were followed through 2007 or 2010 were included in this analysis.

Main outcomes

Migraine or non-migraine headache.

Results

Many females had a history of headaches, with approximately equal numbers reporting symptoms consistent with migraine (29.7%) and non-migraine headaches (25.3%). We found that, independent of age and family history of migraine, each one-year delay in onset of menarche decrease the odds of migraine by 7% (odds ratio (OR) = 0.93, 95% confidence interval (CI) 0.89–0.97), but was not related to non-migraine headaches.

Conclusions and relevance

The findings of this study suggest that early puberty increases the risk of developing migraines by young adulthood. As such, the study emphasizes the need for understanding the pathophysiological links between puberty and developmental changes that occur in the brain during that period and the mechanisms of onset of the migraine disease and its trajectory.

Activational action of testosterone on androgen receptors protects males preventing temporomandibular joint pain

BACKGROUND

Testosterone protects male rats from Temporomandibular Joint (TMJ) pain. This study investigated whether this protective effect is mediated by an organizational action of testosterone during nervous system development, by central estrogen and androgen receptors and by the 5α-reduced metabolite of testosterone, dihydrotestosterone.

METHODS

A pharmacological approach was used to assess the ability of the androgen receptor antagonist flutamide, the estrogen receptor antagonist ICI 182 780 and the 5-α reductase inhibitor dutasteride to block the protective effect of testosterone, evaluated through the behavioral response induced by a TMJ injection of 0.5% formalin. Flutamide and ICI 182 780 were injected into the medullary subarachnoid space, and dutasteride and testosterone were systemically administered.

RESULTS

The TMJ injection of 0.5% formalin induced a significant nociceptive behavioral response in gonadectomized male and naïve female, but not in sham gonadectomized male rats, confirming that endogenous testosterone prevents TMJ nociception in males. Testosterone administration prevented formalin-induced TMJ nociception in males gonadectomized either in the neonatal (at the day of birth) or adult period and in naïve female rats, suggesting that the protective effect of testosterone on TMJ nociception does not depend on its organizational actions during critical periods of development. The administration of flutamide and dutasteride but not of ICI 182 780 blocked the protective effect of testosterone.

CONCLUSIONS

We conclude that the protective effect of testosterone on TMJ nociception depends on activational actions of dihydrotestosterone on androgen receptors rather than on organizational androgenic actions during central nervous system development or estrogenic actions.

Brain Corticosteroid Receptor Dynamics and Trafficking: Implications from Live Cell Imaging

Adrenal corticosteroids (cortisol in humans or corticosterone in rodents) exert numerous effects in the central nervous system that regulate the stress response, mood, learning and memory, and various neuroendocrine functions. Corticosterone actions in the brain are mediated by two corticosteroid receptors, glucocorticoid receptor (GR) and mineralocorticoid receptor (MR), and they show a high degree of colocalization in the hippocampal region. These receptors predominantly reside in the cytoplasm without ligand and are translocated into the nucleus upon ligand binding to act as transcriptional factors. Thus, their subcellualr localizations are an important component of their biological activity. Given the differential action of MR and GR in the central nervous system, it is important to elucidate how the trafficking of these receptors between the cytoplasm and the nucleus and their interactions are regulated by ligand or other molecules to exert transcriptional activity. In this review, the authors focus on the nucleocytoplasmic and subnuclear trafficking of GR and MR in neural cells and nonneural cells and discuss various factors affecting the dynamics of these receptors.

Migraine and Puberty: Potential Susceptible Brain Sites

Puberty is a sensitive and critical period for brain development. The relationship between developmental processes in the brain during puberty and the onset of migraine disease in relation to the potential sites of susceptibility in the brain remains largely unknown. There are few data on how such processes interact with each other in influencing the migraine onset during puberty or even later in adulthood. Focusing on the migraine brain during pubertal development may provide us with a "window of opportunity" both to better understand the mechanisms of the disease and, also more importantly, to effectively intervene.

Simultaneous T1 and T2 Brain Relaxometry in Asymptomatic Volunteers using Magnetic Resonance Fingerprinting

Magnetic resonance fingerprinting (MRF) is an imaging tool that produces multiple magnetic resonance imaging parametric maps from a single scan. Herein we describe the normal range and progression of MRF-derived relaxometry values with age in healthy individuals. In total, 56 normal volunteers (24 men and 32 women) aged 11-71 years were scanned. Regions of interest were drawn on T₁ and T₂ maps in 38 areas, including lobar and deep white matter (WM), deep gray nuclei, thalami, and posterior fossa structures. Relaxometry differences were assessed using a forward stepwise selection of a baseline model that included either sex, age, or both, where variables were included if they contributed significantly (P < .05). In addition, differences in regional anatomy, including comparisons between hemispheres and between anatomical subcomponents, were assessed by paired t tests. MRF-derived T₁ and T₂ in frontal WM regions increased with age, whereas occipital and temporal regions remained relatively stable. Deep gray nuclei such as substantia nigra, were found to have age-related decreases in relaxometry. Differences in sex were observed in T₁ and T₂ of temporal regions, the cerebellum, and pons. Men were found to have more rapid age-related changes in frontal and parietal WM. Regional differences were identified between hemispheres, between the genu and splenium of the corpus callosum, and between posteromedial and anterolateral thalami. In conclusion, MRF quantification measures relaxometry trends in healthy individuals that are in agreement with the current understanding of neurobiology and has the ability to uncover additional patterns that have not yet been explored.

Increased testosterone levels and cortisol awakening responses in patients with borderline personality disorder: gender and trait aggressiveness matter

BACKGROUND

Borderline personality disorder (BPD) is characterized by antagonism, negative affectivity, disinhibition, and impairments in interpersonal functioning, including enhanced impulsive aggression. Interpersonal dysfunctions may be related to alterations in endocrine systems. The current study investigated alterations in basal activity of the hypothalamus-pituitary-gonadal (HPG) reproductive and the hypothalamus-pituitary-adrenal (HPA) stress system in BPD patients and their association to anger-related aggression with a particular focus on effects of gender and comorbid conditions of depression and posttraumatic stress disorder (PTSD).

METHOD

Saliva testosterone levels as well as cortisol awakening responses were assessed in 55 medication-free female and male patients with BPD and compared to 47 gender-, age-, and intelligence-matched healthy volunteers. In addition, analyses controlling for current depression and PSTD and bivariate correlations between testosterone and cortisol levels on the one hand and anger and aggressiveness on the other hand were performed.

RESULTS

The results revealed increased saliva testosterone levels in female and male patients with BPD as well as elevated cortisol awakening responses in female, but not male patients with BPD compared to healthy volunteers. Cortisol awakening responses were positively related to anger and aggressiveness in female patients with BPD, but no associations were found with testosterone levels.

CONCLUSION

In line with previous reports, the present results suggest endocrine alterations in BPD which may be associated with interpersonal impairments, such as increased anger-related aggressive behavior and could have implications for the development of new (psychopharmaco-) therapeutic interventions that may help to restore the alterations in the HPA and HPG systems.

Estrogen-related Receptor β Reduces the Subnuclear Mobility of Estrogen Receptor α and Suppresses Estrogen-dependent Cellular Function

Estrogen-related receptor (ERR) is a member of the nuclear receptor superfamily that has strong homology with estrogen receptor (ER) α. ERR has three subtypes (α, β, and γ) expressed in estrogen-sensitive organs, including ovary, breast, and brain. No endogenous ligands of ERRs have been identified, but these receptors share a common DNA element with ERα and control estrogen-mediated gene transcription. Recent evidence suggests a role of ERRs in estrogen-related pathophysiology, but the detailed mechanisms of ERR functions in estrogen-related tissues are unclear. Using live-cell imaging with fluorescent protein labeling, we found that only ERRβ among the ERRs exhibits a punctate intranuclear pattern overlapping with ERα following 17β-estradiol (E2)-stimulation. Fluorescence recovery after photobleaching showed significant reduction of the mobility of ligand-activated ERα with co-expression of ERRβ. Fluorescence resonance energy transfer revealed that ERRβ directly interacts with ERα. The N-terminal domain of ERRβ was identified as the region that interacts with ERα. We also found a correlation between punctate cluster formation of ERα and interaction between the receptors. Expression of ERRβ significantly repressed ERα-mediated transactivity, whereas that of other ERR subtypes had no effect on the transactivity of ERα. Consistent with this finding, E2-stimulated proliferation of MCF-7 breast carcinoma cells and bcl-2 expression was significantly inhibited by expression of ERRβ. These results provide strong evidence for a suppressive effect of ERRβ on estrogen signaling through reduction of the intranuclear mobility of ERα. The findings further suggest a unique inhibitory role for ERRβ in estrogen-dependent cellular function such as cancer cell proliferation.

17β-estradiol differentially regulates stress circuitry activity in healthy and depressed women

Many regions within stress neurocircuitry, including the anterior hypothalamus, amygdala, hippocampus, and medial prefrontal cortex, are densely populated with sex steroid receptors. Substantial evidence from animal studies indicates that the gonadal hormone 17β-estradiol (E₂) impacts the structure and function of these regions, but human studies are limited. Characterizing estradiol's role in stress circuitry in vivo in humans may have important clinical implications given the comorbidity between major depressive disorder (MDD), stress circuitry dysfunction and endocrine dysregulation. In this study, we determined estradiol's role in modulating activity within cortical and subcortical stress circuitry regions in healthy and MDD women. Subjects were part of a population-based birth cohort, the New England Family Study. Capitalizing on the endogenous fluctuation in E₂ during the menstrual cycle, we conducted a within-person repeated-measures functional neuroimaging study in which 15 women with recurrent MDD, in remission, and 15 healthy control women underwent hormonal evaluations, behavioral testing, and fMRI scanning on two occasions, under low and high E₂ conditions. Subjects completed an fMRI scan while undergoing a mild visual stress challenge that reliably activated stress neural circuitry. Results demonstrate that E₂ modulates activity across key stress circuitry regions, including bilateral amygdala, hippocampus, and hypothalamus. In healthy women, robust task-evoked BOLD signal changes observed under low E₂ conditions were attenuated under high E₂ conditions. This hormonal capacity to regulate activity in stress circuitry was not observed in MDD women, despite their remitted status, suggesting that dysregulation of gonadal hormone function may be a characteristic trait of the disease. These findings serve to deepen our understanding of estradiol's actions in the healthy brain and the neurobiological mechanisms that may underlie the pronounced sex difference in MDD risk.

Evaluation for roles of neurosteroids in modulating forebrain mechanisms controlling vasopressin secretion and related phenomena in conscious rats

Anteroventral third ventricular region (AV3V) that regulates autonomic functions through a GABAergic mechanism possesses neuroactive steroid (NS)-synthesizing ability. Although NS can exert effects by acting on a certain type of GABAA-receptor (R), it is not clear whether NS may operate to modulate AV3V GABAergic activity for controlling autonomic functions. This study aimed to investigate the issue. AV3V infusion with a GABAA antagonist bicuculline increased plasma vasopressin (AVP), glucose, blood pressure (BP), and heart rate in rats. These events were abolished by preinjecting its agonist muscimol, whereas the infusion with allopregnanolone, a NS capable of potentiating GABAA-R function, affected none of the variables in the absence or presence of such bicuculline actions. Similarly, AV3V infusion with pregnanolone sulfate, a NS capable of antagonizing GABAA-R, produced no effect on those variables. AV3V infusion with muscimol was effective in inhibiting the responses of plasma AVP or glucose, or BP to an osmotic loading or bleeding. However, AV3V infusion with aminoglutethimide, a NS synthesis inhibitor, did not affect any of the variables in the absence or presence of those stimuli. These results suggest that NS may not cause acute effects on the AV3V GABAergic mechanism involved in regulating AVP release and other autonomic function.

Prenatal maternal immune disruption and sex-dependent risk for psychoses

BACKGROUND

Previous studies suggest that abnormalities in maternal immune activity during pregnancy alter the offspring's brain development and are associated with increased risk for schizophrenia (SCZ) dependent on sex.

METHOD

Using a nested case-control design and prospectively collected prenatal maternal sera from which interleukin (IL)-1β, IL-8, IL-6, tumor necrosis factor (TNF)-α and IL-10 were assayed, we investigated sex-dependent associations between these cytokines and 88 psychotic cases [SCZ = 44; affective psychoses (AP) = 44] and 100 healthy controls from a pregnancy cohort followed for > 40 years. Analyses included sex-stratified non-parametric tests adjusted for multiple comparisons to screen cytokines associated with SCZ risk, followed by deviant subgroup analyses using generalized estimating equation (GEE) models.

RESULTS

There were higher prenatal IL-6 levels among male SCZ than male controls, and lower TNF-α levels among female SCZ than female controls. The results were supported by deviant subgroup analyses with significantly more SCZ males with high IL-6 levels (>highest quartile) compared with controls [odd ratio (OR)75 = 3.33, 95% confidence interval (CI) 1.13-9.82], and greater prevalence of low TNF-α levels (<lowest quartile) among SCZ females compared with their controls (OR25 = 6.30, 95% CI 1.20-33.04) and SCZ males. Higher levels of IL-6 were only found among SCZ compared with AP cases. Lower TNF-α levels (non-significant) also characterized female AP cases versus controls, although the prevalence of the lowest levels was higher in SCZ than AP females (70% v. 40%), with no effect in SCZ or AP males.

CONCLUSIONS

The results underscore the importance of immunologic processes affecting fetal brain development and differential risk for psychoses depending on psychosis subtype and offspring sex.

Epigenetic changes in the estrogen receptor α gene promoter: implications in sociosexual behaviors

Estrogen action through estrogen receptor α (ERα) is involved in the control of sexual and social behaviors in adult mammals. Alteration of ERα gene activity mediated by epigenetic mechanisms, such as histone modifications and DNA methylation, in particular brain areas appears to be crucial for determining the extents of these behaviors between the sexes and among individuals within the same sex. This review provides a summary of the epigenetic changes in the ERα gene promoter that correlate with sociosexual behaviors.

Sexually dimorphic nuclei in the spinal cord control male sexual functions

Lower spinal cord injuries frequently cause sexual dysfunction in men, including erectile dysfunction and an ejaculation disorder. This indicates that the important neural centers for male sexual function are located within the lower spinal cord. It is interesting that the lumbar spinal segments contain several neural circuits, showing a clear sexually dimorphism that, in association with neural circuits of the thoracic and sacral spinal cord, are critical in expressing penile reflexes during sexual behavior. To date, many sex differences in the spinal cord have been discovered. Interestingly, most of these are male dominant. Substantial evidence of sexually dimorphic neural circuits in the spinal cord have been reported in many animal models, but major issues remain unknown. For example, it is not known how the different circuits cooperatively function during male sexual behavior. In this review, therefore, the anatomical and functional significance of the sexually dimorphic nuclei in the spinal cord corresponding to the expression of male sexual behavior is discussed.

Disruption of fetal hormonal programming (prenatal stress) implicates shared risk for sex differences in depression and cardiovascular disease

Comorbidity of major depressive disorder (MDD) and cardiovascular disease (CVD) represents the fourth leading cause of morbidity and mortality worldwide, and women have a two times greater risk than men. Thus understanding the pathophysiology has widespread implications for attenuation and prevention of disease burden. We suggest that sex-dependent MDD-CVD comorbidity may result from alterations in fetal programming consequent to the prenatal maternal environments that produce excess glucocorticoids, which then drive sex-dependent developmental alterations of the fetal hypothalamic-pituitary-adrenal (HPA) axis circuitry impacting mood, stress regulation, autonomic nervous system (ANS), and the vasculature in adulthood. Evidence is consistent with the hypothesis that disruptions of pathways associated with gamma aminobutyric acid (GABA) in neuronal and vascular development and growth factors have critical roles in key developmental periods and adult responses to injury in heart and brain. Understanding the potential fetal origins of these sex differences will contribute to development of novel sex-dependent therapeutics.

Insights into lipidomic perturbations in zebrafish tissues upon exposure to microcystin-LR and microcystin-RR

This work represents the first study of its kind that was conducted to evaluate changes in lipid metabolic networks following a balneation exposure of adult zebrafish to MCLR (microcystin-leucine-arginine) and MCRR (microcystin-arginine-arginine) at a sublethal dose (10 μg L(-1)) for a period of 30 days. Following the exposure to MCLR and MCRR, gills, liver, intestine, and brain tissues were harvested for metabolite extraction. Extracted metabolites were detected using qTOF-LC-MS (time-of-flight-liquid chromatography-mass spectrometry). Metabolites were identified using Kegg pathways. The identified metabolites are shown on lipid biochemical maps to demonstrate major perturbations in the metabolic machinery. Results showed that most of the metabolic pathways under the lipid class were affected in different tissues of zebrafish following the exposure to MCLR and MCRR (10 μg L(-1) for 30 days). The kind and flux of metabolic perturbations varied among different tissues of the organs after the exposure to MCLR and MCRR with the tissues of gills being the most affected. Among the various lipid pathways, cholesterol synthesis was affected significantly as observed from the highest number of perturbed metabolites in that pathway. Cholesterol is responsible for synthesis of steroid hormones and bile acids, which have been recognized as endocrine signaling molecules. Disruption in the synthesis of these compounds following MCLR/MCRR exposure suggests that MCs are capable of causing endocrine disruption among aquatic organisms even under sublethal conditions. Apart from cholesterol synthesis, various other metabolic pathways belonging to the class of essential fatty acids and lipid oxidation were also observed to be perturbed following a balneation exposure of zebrafish to MCLR/MCRR.

17β-Estradiol alters the response of subfornical organ neurons that project to supraoptic nucleus to plasma angiotensin II and hypernatremia

This study was done in urethane anesthetized, ovariectomized (OVX) female rats that were either implanted or not implanted with silastic capsules containing17β-estradiol (E2) to investigate the effect of systemic changes in E2 on the discharge rate of subfornical organ (SFO) neurons that projected to supraoptic nucleus (SON) and responded to changes in plasma levels of angiotensin II (ANG II) or hypernatremia. Extracellular single unit recordings were made from 146 histologically verified single units in SFO. Intra-carotid infusions of ANG II excited ~57% of these neurons, whereas ~23% were excited by hypertonic NaCl. Basal discharge rate of neurons excited by ANG II or hypertonic NaCl was significantly lower in OVX+E2 rats compared to OVX only animals. The response of SFO neurons antidromically activated by SON stimulation to intra-carotid injections of ANG II or hypertonic NaCl was greater in the OVX only compared to the OVX+E2 rats. Intra-carotid injections of E2 in either group attenuated not only the basal discharge of these neurons, but also their response to ANG II or hypertonic NaCl. In all cases this inhibitory effect of E2 was blocked by an intra-carotid injection of the E2 receptor antagonist ICI-182780, although ICI-182780 did not alter the neuron's response to ANG II or hypertonic NaCl. Additionally, ICI-182780 in the OVX+E2 animals significantly raised the basal discharge of SFO neurons and their response to ANG II or hypertonic NaCl. These data indicate that E2 alters the response of SFO neurons to ANG II or NaCl that project to SON, and suggest that E2 functions in the female to regulate neurohypophyseal function in response to circulating ANG II and plasma hypernatremia.

Cryptic confounding compounds: A brief consideration of the influences of anthropogenic contaminants on courtship and mating behavior

Contaminants, like pesticides, polychlorinated biphenyls (PCBs), dioxins and metals, are persistent and ubiquitous and are known to threaten the environment. Traditionally, scientists have considered the direct physiological risks that these contaminants pose. However, scientists have just begun to integrate ethology and toxicology to investigate the effects that contaminants have on behavior. This review considers the potential for contaminant effects on mating behavior. Here we assess the growing body of research concerning disruptions in sexual differentiation, courtship, sexual receptivity, arousal, and mating. We discuss the implications of these disruptions on conservation efforts and highlight the importance of recognizing the potential for environmental stressors to affect behavioral experimentation. More specifically, we consider the negative implications for anthropogenic contaminants to affect the immediate behavior of animals, and their potential to have cascading and/or long-term effects on the behavioral ecology and evolution of populations. Overall, we aim to raise awareness of the confounding influence that contaminants can have, and promote caution when interpreting results where the potential for cryptic affects are possible.