Emerging Roles of Estrogen-Related Receptors in the Brain: Potential Interactions with Estrogen Signaling

Latent class analysis of migraine associated vestibular-auditory symptoms

OBJECTIVE

This study aimed to identify the potential subgroups of migraines based on the patterns of migraine associated symptoms, vestibular and auditory symptoms using latent class analysis and to explore their characteristics.

METHOD

A total of 555 patients with migraine participated in the study. Symptoms such as nausea, vomiting, photophobia, phonophobia, osmophobia, visual symptoms, vestibular symptoms (dizziness, vertigo), and auditory symptoms (tinnitus, hearing loss, aural fullness) were assessed. Latent class analysis was performed to identify subgroups of migraines. Covariates such as gender, age of migraine onset, frequency of migraine attacks per month, and family history were also considered.

RESULTS

The analysis revealed four latent classes: the Prominent Vestibular; Prominent Nausea; Presenting Symptoms but not prominent or dominant; and Sensory Hypersensitivity groups. Various covariates, such as gender, age of migraine onset, and frequency of migraine attacks, demonstrated significant differences among the four groups. The Sensory Hypersensitivity group showed the presence of multiple sensory symptoms, earlier age of migraine onset, and higher proportion of females. The Prominent Vestibular group had the highest probability of dizziness or vertigo but lacked the presence of auditory symptoms. The Prominent Nausea group exhibited prominent nausea. The Presenting Symptoms but not prominent or dominant group comprised individuals with the highest migraine attacks per month and proportion of chronic migraine.

CONCLUSION

This study identifies four subgroups of migraines based on the patterns of symptoms. The findings suggest potential different but overlapped mechanisms behind the vestibular and auditory symptoms of migraine. Considering the different patterns of migraine-related symptoms may provide deeper insights for patients' prognosis and clinical decision-making.

Modeling methamphetamine use disorder and relapse in animals: short- and long-term epigenetic, transcriptional., and biochemical consequences in the rat brain

Methamphetamine use disorder (MUD) is a neuropsychiatric disorder characterized by binge drug taking episodes, intervals of abstinence, and relapses to drug use even during treatment. MUD has been modeled in rodents and investigators are attempting to identify its molecular bases. Preclinical experiments have shown that different schedules of methamphetamine self-administration can cause diverse transcriptional changes in the dorsal striatum of Sprague-Dawley rats. In the present review, we present data on differentially expressed genes (DEGs) identified in the rat striatum following methamphetamine intake. These include genes involved in transcription regulation, potassium channel function, and neuroinflammation. We then use the striatal data to discuss the potential significance of the molecular changes induced by methamphetamine by reviewing concordant or discordant data from the literature. This review identified potential molecular targets for pharmacological interventions. Nevertheless, there is a need for more research on methamphetamine-induced transcriptional consequences in various brain regions. These data should provide a more detailed neuroanatomical map of methamphetamine-induced changes and should better inform therapeutic interventions against MUD.

The marijuana-schizophrenia multifaceted nexus: Connections and conundrums towards neurophysiology

Delta-9-tetrahydrocannabinol, a component of marijuana, interacts with cannabinoid receptors in brain involved in memory, cognition, and emotional control. However, marijuana use and schizophrenia development is a complicated and contentious topic. As a result, more investigation is needed to understand this relationship. Through the functional enrichment analysis, we report the delta-9-tetrahydrocannabinol to manipulate the homeostatic biological process and molecular function of different macromolecules. Additionally, using molecular docking and subsequent processing for molecular simulations, we assessed the binding ability of delta-9-tetrahydrocannabinol with the estrogen-related protein, dopamine receptor 5, and hyaluronidase. It was found that delta-9-tetrahydrocannabinol may have an impact on the brain's endocannabinoid system and may trigger the schizophrenia progression in vulnerable people. Delta-9-tetrahydrocannabinol may interfere with the biological function of 18 proteins linked to schizophrenia and disrupt the synaptic transmission (dopamine, glutamine, and gamma-aminobutyric acid). It was discovered that it may affect lipid homeostasis, which is closely related to membrane integrity and synaptic plasticity. The negative control of cellular and metabolic processes, fatty acids binding /activity, and the manipulated endocannabinoid system (targeting cannabinoid receptors) were also concerned with delta-9-tetrahydrocannabinol. Hence, this may alter neurotransmitter signaling involved in memory, cognition, and emotional control, showing its direct impact on brain physiological processes. This may be one of the risk factors for schizophrenia development which is also closely tied to some other variables such as frequency, genetic vulnerability, dosage, and individual susceptibility.

Activation of estrogen-related receptor: An alternative mechanism of hexafluoropropylene oxide homologs estrogenic effects

Perfluorooctanoic acid (PFOA) alternatives such as hexafluoropropylene oxide homologs (HFPOs) cause concern due to increased occurrence in the environment as well as potential bioaccumulation and toxicity. HFPOs have been demonstrated to activate the estrogen receptor (ER) pathway. The ER pathway is homologous and connected to the estrogen-related receptor (ERR) pathway, but HFPOs effects on the ERR pathway have not been studied. Hence, we assessed the potential estrogenic effects of HFPOs via ERRγ pathway. In vitro assays revealed that HFPO dimeric, trimeric, and tetrameric acids (HFPO-DA, -TA, and -TeA, respectively), acted as ERRγ agonists, activating the transcription of both human and zebrafish ERRγ at low concentrations, but inhibiting zebrafish ERRγ at high concentrations. We also found that HFPO-TA promoted the human endometrial cancer cells (Ishikawa cells) proliferation via ERRγ/EGF, Cyclin D1 pathway. The HFPO-TA-induced proliferation of Ishikawa cells was inhibited by co-exposure with a specific antagonist of ERRγ, GSK5182. In vivo exposure of female zebrafish to HFPO-TA disturbed sex hormone levels, interfered with the gene expression involved in estrogen synthesis and follicle regulation, and caused histopathological lesions in the ovaries, which were similar to those induced by a known ERRγ agonist GSK4716. Taken together, this study revealed a new mechanism concerning the estrogenic effect of HFPOs via activation of the ERRγ pathway.

Oral combined hormonal contraceptive associated with protection against allodynia in migraine in a cross-sectional study

INTRODUCTION

For the most part, migraine afflicts young women who often need to use the hormonal contraceptive method.

OBJECTIVE

To evaluate the effects of using exogenous estrogen, present in combined hormonal contraceptives (CHC) and progestin-only methods on the prevalence of allodynia in women with migraine.

METHODS

Study comprising women diagnosed with migraine, with or without aura, who were not pregnant, breastfeeding, or menopausal. The study was conducted via the digital platform. Data were collected relating to demographics, contraceptive method, anthropometric information, smoking habits, and migraine-related symptoms. The participants then answered the following validated, self-administered questionnaires: Migraine Disability Assessment (MIDAS), Allodynia Symptom Checklist, Generalized Anxiety Disorder (GAD-7), and Beck's Depression Inventory (BDI). In order to determine the variables associated with allodynia, two binary logistic regression models were used.

RESULTS

Four hundred eighty-six women took part in the study. Of these, 205 used CHC, 89 used a progestin-only method, and 192 participants did not use any form of hormonal contraception. Allodynia was identified in 411 (84.6%) participants. Allodynia was linked to the presence of aura (OR = 2.76; CI 95% 1.55-4.91; p = 0.001), menstrually related migraine (OR = 2.14; CI 95% 1.28-3.57; p = 0.004), greater disability (MIDAS score 23 vs. 8; p < 0.001), depression (BDI score 14 vs. 10; p < 0.001), and anxiety (GAD-7 score 11 vs. 8; p < 0.001). In adjusted analysis, CHC was associated to protection against allodynia when jointly evaluated all CHC regimens (OR = 0.49 CI 95% 0.26-0.92; p = 0.028), as well as oral CHC individually (OR = 0.48 CI 95% 0.25-0.92; p = 0.027).

CONCLUSION

CHC reduced the chances of women with migraine getting allodynia.

Zebrafish as an emerging model to study estrogen receptors in neural development

Estrogens induce several regulatory signals in the nervous system that are mainly mediated through estrogen receptors (ERs). ERs are largely expressed in the nervous system, yet the importance of ERs to neural development has only been elucidated over the last decades. Accumulating evidence shows a fundamental role for estrogens in the development of the central and peripheral nervous systems, hence, the contribution of ERs to neural function is now a growing area of research. The conservation of the structure of the ERs and their response to estrogens make the zebrafish an interesting model to dissect the role of estrogens in the nervous system. In this review, we highlight major findings of ER signaling in embryonic zebrafish neural development and compare the similarities and differences to research in rodents. We also discuss how the recent generation of zebrafish ER mutants, coupled with the availability of several transgenic reporter lines, its amenability to pharmacological studies and in vivo live imaging, could help us explore ER function in embryonic neural development.

Immunomodulatory role of estrogen in ischemic stroke: neuroinflammation and effect of sex

Although estrogen is predominantly related to the maintenance of reproductive functioning in females, it mediates various physiological effects in nearly all tissues, especially the central nervous system. Clinical trials have revealed that estrogen, especially 17β-estradiol, can attenuate cerebral damage caused by an ischemic stroke. One mechanism underlying this effect of 17β-estradiol is by modulating the responses of immune cells, indicating its utility as a novel therapeutic strategy for ischemic stroke. The present review summarizes the effect of sex on ischemic stroke progression, the role of estrogen as an immunomodulator in immune reactions, and the potential clinical value of estrogen replacement therapy. The data presented here will help better understand the immunomodulatory function of estrogen and may provide a basis for its novel therapeutic use in ischemic stroke.

Ligand pathways in estrogen-related receptors

The three subtypes of estrogen-related receptors ERRα, ERRβ, and ERRγ are nuclear receptors mediating metabolic processes in various tissues such as the skeletal muscle, fat tissue, bone, and liver. Although the knowledge on their physiological ligands is limited, they have been implicated as drug targets for important indications including diabetes, cardiovascular diseases, and osteoporosis. As in other nuclear receptors, their ligand binding pocket is buried within the core of the receptor and connected to its surrounding by ligand pathways. Here, we investigated these pathways with conventional molecular dynamics as well as metadynamics simulations to reveal their distribution and their capability to facilitate ligand translocation. Dependent on the ERR subtype and the conformational state of the receptor, we could detect different pathways to be favored. Overall, the results suggested pathways IIIa and IIIb to be favored in the agonistic conformation, while antagonists preferred pathways I, II, and V. Along the pathways, the ligands passed different gating mechanisms of the receptor, including groups of protein residues as well as whole secondary structure elements, to leave the binding site. Even though these pathways are suggested to influence ligand specificity of the receptors and their elucidation might advance rational drug design, they have not yet been studied in ERRs.Communicated by Ramaswamy H. Sarma.

Multifaceted Transcriptional Network of Estrogen-Related Receptor Alpha in Health and Disease

Estrogen-related receptors (ERRα, β and γ in mammals) are orphan members of the nuclear receptor superfamily acting as transcription factors. ERRs are expressed in several cell types and they display various functions in normal and pathological contexts. Amongst others, they are notably involved in bone homeostasis, energy metabolism and cancer progression. In contrast to other nuclear receptors, the activities of the ERRs are apparently not controlled by a natural ligand but they rely on other means such as the availability of transcriptional co-regulators. Here we focus on ERRα and review the variety of co-regulators that have been identified by various means for this receptor and their reported target genes. ERRα cooperates with distinct co-regulators to control the expression of distinct sets of target genes. This exemplifies the combinatorial specificity of transcriptional regulation that induces discrete cellular phenotypes depending on the selected coregulator. We finally propose an integrated view of the ERRα transcriptional network.

Roles of Estrogen, Estrogen Receptors, and Estrogen-Related Receptors in Skeletal Muscle: Regulation of Mitochondrial Function

Estrogen is an essential sex steroid hormone that functions primarily in female reproductive system, as well as in a variety of tissues and organs with pleiotropic effects, such as in cardiovascular, nervous, immune, and musculoskeletal systems. Women with low estrogen, as exemplified by those in postmenopause, are therefore prone to suffer from various disorders, i.e., cardiovascular disease, dementia, metabolic syndrome, osteoporosis, sarcopenia, frailty, and so on. Estrogen regulates the expression of its target genes by binding to its cognate receptors, estrogen receptors (ERs) α and β. Notably, the estrogen-related receptors (ERRs) α, β, and γ are originally identified as orphan receptors that share substantial structural homology and common transcriptional targets with ERs. Accumulating evidence suggests that ERs and ERRs play crucial roles in skeletal muscles, such as muscle mass maintenance, muscle exercise physiology, and muscle regeneration. In this article, we review potential regulatory roles of ERs and ERRs in muscle physiology, particularly with regard to mitochondrial function and metabolism.

Role of sex hormones in diabetic nephropathy

Diabetic nephropathy (DN) is the most common microvascular complication in diabetes and one of the leading causes of end-stage renal disease. The standard treatments for patients with classic DN focus on blood glucose and blood pressure control, but these treatments can only slow the progression of DN instead of stopping or reversing the disease. In recent years, new drugs targeting the pathological mechanisms of DN (e.g., blocking oxidative stress or inflammation) have emerged, and new therapeutic strategies targeting pathological mechanisms are gaining increasing attention. A growing number of epidemiological and clinical studies suggest that sex hormones play an important role in the onset and progression of DN. Testosterone is the main sex hormone in males and is thought to accelerate the occurrence and progression of DN. Estrogen is the main sex hormone in females and is thought to have renoprotective effects. However, the underlying molecular mechanism by which sex hormones regulate DN has not been fully elucidated and summarized. This review aims to summarize the correlation between sex hormones and DN and evaluate the value of hormonotherapy in DN.

Binding and Activation of Estrogen-Related Receptor γ: A Novel Molecular Mechanism for the Estrogenic Disruption Effects of DDT and Its Metabolites

DDT and its metabolites (DDTs) can induce estrogenic effects. Previous mechanistic investigations mainly concentrated on activating the genomic transcription of estrogen receptor (ER) pathways. Here, we identified whether estrogen-related receptor γ (ERRγ), an orphan nuclear receptor, is a potential target of DDTs by receptor binding, transcriptional activity, and receptor-mediated pathway assays. Fluorescence polarization-based binding assays showed that all eight DDTs bound to ERRγ directly, with K_d values ranging from 0.73-168.82 μM. Among them, 2,2-bis(4-chlorophenyl)ethanol (4,4'-DDOH) exhibited the highest binding affinity, which was 2.5-fold stronger than GSK4716, a well-known ERRγ agonist. Eight DDTs exhibited agonistic activity toward the ERRγ pathway, with 4,4'-DDOH showing the strongest potency. In silico studies revealed that DDTs tended to bind with ERRγ in the agonistic conformation. Using a SKBR3 breast cancer cell model, we further found that nanomolar or micromolar levels of DDTs significantly activated the ERRγ pathway in cells and induced cell proliferation through the ERRγ-modulated cell cycle. These results indicated that the binding and activation of DDTs to ERRγ might serve as molecular initiating events for subsequent ERRγ-mediated signaling pathways and adverse outcomes. Overall, our results demonstrated that ERRγ might be a crucial pathway involved in the estrogenic disruption effects of DDTs.

Reproductive hormone levels, androgen receptor CAG repeat length and their longitudinal relationships with decline in cognitive subdomains in men: The European Male Ageing Study

OBJECTIVE

It has been proposed that endogenous sex hormone levels may present a modifiable risk factor for cognitive decline. However, the evidence for effects of sex steroids on cognitive ageing is conflicting. We therefore investigated associations between endogenous hormone levels, androgen receptor CAG repeat length, and cognitive domains including visuoconstructional abilities, visual memory, and processing speed in a large-scale longitudinal study of middle-aged and older men.

METHODS

Men aged 40-79 years from the European Male Ageing Study (EMAS) underwent cognitive assessments and measurements of hormone levels at baseline and follow-up (mean = 4.4 years, SD ± 0.3 years). Hormone levels measured included total and calculated free testosterone and estradiol, dihydrotestosterone, luteinizing hormone, follicle-stimulating hormone, dehydroepiandrosterone sulphate and sex hormone-binding globulin. Cognitive function was assessed using the Rey-Osterrieth Complex Figure Copy and Recall, the Camden Topographical Recognition Memory and the Digit Symbol Substitution Test. Multivariate linear regressions were used to examine associations between baseline and change hormone levels, androgen receptor CAG repeat length, and cognitive decline.

RESULTS

Statistical analyses included 1,827 and 1,423 participants for models investigating relationships of cognition with hormone levels and CAG repeat length, respectively. In age-adjusted models, we found a significant association of higher baseline free testosterone (β=-0.001, p=0.005) and dihydrotestosterone levels (β=-0.065, p=0.003) with greater decline on Rey-Osterrieth Complex Figure Recall over time. However, these effects were no longer significant following adjustment for centre, health, and lifestyle factors. No relationships were observed between any other baseline hormone levels, change in hormone levels, or androgen receptor CAG repeat length with cognitive decline in the measured domains.

CONCLUSIONS

In this large-scale prospective study there was no evidence for an association between endogenous sex hormone levels or CAG repeat length and cognitive ageing in men. These data suggest that sex steroid levels do not affect visuospatial function, visual memory, or processing speed in middle-aged and older men.

The underlying sex differences in neuroendocrine adaptations relevant to Myalgic Encephalomyelitis Chronic Fatigue Syndrome

INTRODUCTION

Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome (ME/CFS) is a complex multisystem disease characterised by severe and disabling new-onset symptoms of post-exertional malaise (PEM), fatigue, brain fog, and sleep dysfunction that lasts for at least six months. Accumulating evidence suggests that sex and endocrine events have a significant influence on symptom onset and moderation of ME/CFS, with female sex being one of the most consistent and credible predictive risk factors associated with diagnosis. Such sex differences suggest sex chromosomes and sex steroids may play a part in the development of the condition or moderation of symptoms, although this has yet to be explored in detail.

METHODS/AIMS

This narrative review outlines sex differences in ME/CFS in terms of vulnerability factors and clinical phenotype and explores the known sex differences in neuroendocrine systems affected in ME/CFS and how this may relate to disease risk, onset, pathophysiology, and potential treatment avenues.

CONCLUSIONS

There is clear evidence of a sex dimorphism with regards to prevalence (3:1 female preponderance), clinical phenotypes, and aetiological triggers prior to symptom onset of ME/CFS. Endocrinological events, particularly those throughout the female lifespan, are associated with ME/CFS and include reproductive menstrual cycle fluctuations, pregnancy, post-partum and perimenopause. Further, there is evidence for gonadal sex, adrenal stress and renal neuroendocrine systems as implicated in ME/CFS, including changes in estrogen, progesterone compounds, aldosterone, and cortisol levels, of which there are established sex differences. The broad effects of steroid hormones on the physiological systems may also speak to the diversity of ME/CFS symptomatology observed in patients. Further attention must be paid to sex, age, and steroid biology in ME/CFS.

Social status mediated variation in hypothalamic transcriptional profiles of male mice

Animals of different social status exhibit variation in aggression, territorial and reproductive behavior as well as activity patterns, feeding, drinking and status signaling. This behavioral and physiological plasticity is coordinated by underlying changes in brain gene transcription. Using Tag-based RNA sequencing (Tag-seq), we explore RNA transcriptomes from the medial preoptic area (mPOA) and ventral hypothalamus (vHYP) of male mice of different social ranks in a dominance hierarchy and detect candidate genes and cellular pathways that underlie status-related plasticity. Within the mPOA, oxytocin (Oxt) and vasopressin (Avp) are more highly expressed in subdominant mice compared to other ranks, while nitric oxide synthase (Nos1) has lower expression in subdominant mice. Within the vHYP, we find that both orexigenic and anorexigenic genes involved in feeding behavior, including agouti-related peptide (Agrp), neuropeptide-Y (Npy), galanin (Gal), proopiomelanocortin (Pomc), and Cocaine- and Amphetamine-Regulated Transcript Protein prepropeptide (Cartpt), are less expressed in dominant animals compared to more subordinate ranks. We suggest that this may represent a reshaping of feeding circuits in dominant compared to subdominant and subordinate animals. Furthermore, we determine several genes that are positively and negatively associated with the level of despotism (aggression) in dominant males. Ultimately, we identify hypothalamic genes controlling feeding and social behaviors that are differentially transcribed across animals of varying social status. These changes in brain transcriptomics likely support phenotypic variation that enable animals to adapt to their current social status.

Discovery of new ERRγ agonists regulating dopaminergic neuronal phenotype in SH-SY5Y cells

The discovery of small molecules that regulate specific neuronal phenotypes is important for the development of new therapeutic candidates for neurological diseases. Estrogen-related receptor γ (ERRγ), an orphan nuclear receptor widely expressed in the central nervous system (CNS), is closely related to the regulation of neuronal metabolism and differentiation. We previously reported that upregulation of ERRγ could enhance dopaminergic neuronal phenotypes in the neuroblastoma cell line, SH-SY5Y. In this study, we designed and synthesized a series of new ERRγ agonists using the X-ray crystal structure of the GSK4716-bound ERRγ complex and known synthetic ligands. Our new ERRγ agonists exhibited increased transcriptional activities of ERRγ. In addition, our molecular docking results supported the experimental findings for ERRγ agonistic activity of the potent analogue, 5d. Importantly, 5d not only enhanced the expression of dopaminergic neuronal-specific molecules, TH and DAT but also activated the relevant signaling events, such as the CREB-mediated signaling pathway. The results of the present study may provide useful clues for the development of novel ERRγ agonists for neurological diseases related to the dopaminergic nervous system.

Voluntary wheel running alters markers of amyloid-beta precursor protein processing in an ovarian hormone depleted model

INTRODUCTION

Aberrant cleavage of the transmembrane protein, amyloid-beta precursor protein (ABPP), results in the overproduction of amyloid-beta (AB) peptides which can form senile plaques in the brain. These plaques can get lodged within synapses and disrupt neuronal communication ultimately leading to rampant neuron death. The rate-limiting enzyme in AB production is beta-site ABPP cleaving enzyme 1 (BACE1). In females, estrogen loss is associated with increases in AB and BACE1 content and activity. Exercise is known to have anti-amyloidogenic effects and may be able to alter BACE1 in cases of ovarian hormone depletion. This study aimed to examine the effects of physical activity on BACE1 in intact and ovariectomized female mice.

METHODS

Female C57BL/6 mice (24 weeks old) underwent bilateral ovariectomy (OVX; n=20) or SHAM surgery (SHAM; n=20). Mice were assigned to one of four groups (n=10/group) for 8 weeks: (1) sham (SHAM), (2) sham with a wheel (SHAM VWR), (3) ovariectomized (OVX), or (4) ovariectomized with a wheel (OVX VWR).

RESULTS

Novel object recognition testing demonstrated that OVX mice had a lower percentage of novel object investigation time compared to SHAM. OVX mice also had higher prefrontal cortex BACE1 activity compared to SHAM (p<0.0001), while the OVX+VWR activity was not different from SHAM.

DISCUSSIONS

Our results demonstrate that voluntary wheel running in an ovariectomized model prevented increases in BACE1 activity, maintained memory recall, and may provide a method of slowing the progression of Alzheimer's disease.

Estrogen-related Receptor Alpha (ERRα) is Required for PGC-1α-dependent Gene Expression in the Mouse Brain

Deficiency in peroxisome proliferator-activated receptor gamma coactivator 1-alpha. (PGC-1α) expression or function is implicated in numerous neurological and psychiatric disorders. PGC-1α is required for the expression of genes involved in synchronous neurotransmitter release, axonal integrity, and metabolism, especially in parvalbumin-positive interneurons. As a transcriptional coactivator, PGC-1α requires transcription factors to specify cell-type-specific gene programs; while much is known about these factors in peripheral tissues, it is unclear if PGC-1α utilizes these same factors in neurons. Here, we identified putative transcription factors controlling PGC-1α-dependent gene expression in the brain using bioinformatics and then validated the role of the top candidate in a knockout mouse model. We transcriptionally profiled cells overexpressing PGC-1α and searched for over-represented binding motifs in the promoters of upregulated genes. Binding sites of the estrogen-related receptor (ERR) family of transcription factors were enriched, and blockade of ERRα attenuated PGC-1α-mediated induction of mitochondrial and synaptic genes in cell culture. Localization in the mouse brain revealed enrichment of ERRα expression in parvalbumin-expressing neurons with tight correlation of expression with PGC-1α across brain regions. In ERRα null mice, PGC-1α-dependent genes were reduced in multiple regions, including neocortex, hippocampus, and cerebellum, though not to the extent observed in PGC-1α null mice. Behavioral assessment revealed ambulatory hyperactivity in response to amphetamine and impairments in sensorimotor gating without the overt motor impairment characteristic of PGC-1α null mice. These data suggest that ERRα is required for normal levels of expression of PGC-1α-dependent genes in neurons but that additional factors may be involved in their regulation.

The Inequality of Females in Bladder Cancer

Urinary bladder cancer is worldwide one of the most diagnosed and costly types of cancer. One puzzle in the bladder cancer diagnosis is the disproportional relationship between genders. Males are more likely to be diagnosed with bladder cancer whereas females typically are diagnosed with more adverse disease and worse prognosis, which has led to speculation of the potential role of sex hormones and their receptors in this disease. Estrogen receptors are present in the human bladder, and their role in bladder cancer oncogenesis is increasingly becoming a focus for researchers around the world. This mini-review aims to give a brief overview of the status of female bladder cancer, and to which extend the sex hormones receptors play a role in this. A literature search was performed and included all female original studies on bladder cancer and hormone receptors. Estrogen-receptor alpha seems to be anti-oncogenic whereas estrogen-receptor beta is exhibiting its function pro-oncogenic. The receptor functions may be exercised through mRNA transcriptions and enzymes. Epidemiological studies indicate a potential increase in incidence of bladder cancer for females with earlier age at menopause, and clinical trials are investigating Tamoxifen as a potential treatment in bladder cancer. Increasing evidence supports the theory of bladder cancer development and progression as being partly hormone-dependent. This can lead to a change in conceptual background of bladder cancer etiology and development in the future. Further studies are required to more precise map the use of anti-hormonal drugs in the treatment of this cancer.

Abundance of estrogen receptors involved in non-canonical signaling in the dog testis

With estrogen regulation of the reproductive system, G-protein-coupled membrane estrogen receptor (GPER) and estrogen-related receptors (ERRs) are implicated. Non-canonical receptors can bind estrogens such as environmental and pharmacological chemicals. These compounds induce rapid non-genomic pathways or receptor interaction including autoactivation. Testicular tumors occur in dogs more frequently than in other domestic animals. Also, in recent decades there were increased occurrences of various tumor types in dogs. Using qRT-PCR, Western blot and immunohistochemistry procedures in the present study, there was determination of abundance pattern of GPER, ERRα, β and γ in dog tests when there were intratubular germ cell tumors. There was quantitation of estradiol, cyclic GMP and calcium ions (Ca2⁺). There were changes (P < 0.01; P < 0.001) in GPER, ERRα and β in both mRNA transcript and protein abundances including less (P < 0.001) co-abundance of ERRγ mRNA transcript and protein. Receptors were mainly located in Leydig cells with there being receptor delocalization to the cell cytoplasm or occasionally detections in the seminiferous tubule epithelia, especially of testicular tumor tissues. There were also greater estradiol (P < 0.05) and lesser cGMP and Ca2⁺ concentrations in testicular tumor tissues indicating there was a disrupted sex steroid milieu and tumor cell metastasis. Results from the present study provide further evidence that ERRγ has marked actions in testicular germ cell tumor initiation and development and in further structural-functional disruptions of dog testis. Concomitantly, abundance pattern of GPER and ERRs, relative to concentrations of cGMP and Ca2⁺, may be an additional indicator of intratubular germ cell tumors in dogs.

Estradiol Protects against Noise-Induced Hearing Loss and Modulates Auditory Physiology in Female Mice

Recent studies have identified sex-differences in auditory physiology and in the susceptibility to noise-induced hearing loss (NIHL). We hypothesize that 17β-estradiol (E2), a known modulator of auditory physiology, may underpin sex-differences in the response to noise trauma. Here, we gonadectomized B6CBAF1/J mice and used a combination of electrophysiological and histological techniques to study the effects of estrogen replacement on peripheral auditory physiology in the absence of noise exposure and on protection from NIHL. Functional analysis of auditory physiology in gonadectomized female mice revealed that E2-treatment modulated the peripheral response to sound in the absence of changes to the endocochlear potential compared to vehicle-treatment. E2-replacement in gonadectomized female mice protected against hearing loss following permanent threshold shift (PTS)- and temporary threshold shift (TTS)-inducing noise exposures. Histological analysis of the cochlear tissue revealed that E2-replacement mitigated outer hair cell loss and cochlear synaptopathy following noise exposure compared to vehicle-treatment. Lastly, using fluorescent in situ hybridization, we demonstrate co-localization of estrogen receptor-2 with type-1C, high threshold spiral ganglion neurons, suggesting that the observed protection from cochlear synaptopathy may occur through E2-mediated preservation of these neurons. Taken together, these data indicate the estrogen signaling pathways may be harnessed for the prevention and treatment of NIHL.

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.

Inhibition of mitochondrial pyruvate carrier 1 by lapatinib ditosylate mitigates Alzheimer's-like disease in D-galactose/ovariectomized rats

Mitochondrial, autophagic impairment, excitotoxicity, and also neuroinflammation are implicated in Alzheimer's disease (AD) pathophysiology. We postulated that inhibiting the mitochondrial pyruvate carrier-1 (MPC-1), which inhibits the activation of the mammalian target of rapamycin (mTOR), may ameliorate the neurodegeneration of hippocampal neurons in the rat AD model. To assess this, we used lapatinib ditosylate (LAP), an anti-cancer drug that inhibits MPC-1 through suppression of estrogen-related receptor-alpha (ERR-α), in D-galactose/ovariectomized rats. AD characteristics were developed in ovariectomized (OVX) rats following an 8-week injection of D-galactose (D-gal) (150 mg/kg, i.p.). The human epidermal growth factor receptor-2 (HER-2) inhibitor, LAP (100 mg/kg, p.o.) was daily administered for 3 weeks. LAP protected against D-gal/OVX-induced changes in cortical and hippocampal neurons along with improvement in learning and memory, as affirmed using Morris water maze (MWM) and novel object recognition (NOR) tests. Furthermore, LAP suppressed the hippocampal expression of Aβ1-42, p-tau, HER-2, p-mTOR, GluR-II, TNF-α, P38-MAPK, NOX-1, ERR-α, and MPC-1. Also, LAP treatment leads to activation of the pro-survival PI3K/Akt pathway. As an epilogue, targeting MPC-1 in the D-gal-induced AD in OVX rats resulted in the enhancement of autophagy, and suppression of neuroinflammation and excitotoxicity. Our work proves that alterations in metabolic signaling as a result of inhibiting MPC-1 were anti-inflammatory and neuroprotective in the AD model, revealing that HER-2, MPC-1, and ERR-α may be promising therapeutic targets for AD.

Low-Dose Radiation Can Cause Epigenetic Alterations Associated With Impairments in Both Male and Female Reproductive Cells

Humans are regularly and continuously exposed to ionizing radiation from both natural and artificial sources. Cumulating evidence shows adverse effects of ionizing radiation on both male and female reproductive systems, including reduction of testis weight and sperm count and reduction of female germ cells and premature ovarian failure. While most of the observed effects were caused by DNA damage and disturbance of DNA repairment, ionizing radiation may also alter DNA methylation, histone, and chromatin modification, leading to epigenetic changes and transgenerational effects. However, the molecular mechanisms underlying the epigenetic changes and transgenerational reproductive impairment induced by low-dose radiation remain largely unknown. In this study, two different types of human ovarian cells and two different types of testicular cells were exposed to low dose of ionizing radiation, followed by bioinformatics analysis (including gene ontology functional analysis and Ingenuity Pathway Analysis), to unravel and compare epigenetic effects and pathway changes in male and female reproductive cells induced by ionizing radiation. Our findings showed that the radiation could alter the expression of gene cluster related to DNA damage responses through the control of MYC. Furthermore, ionizing radiation could lead to gender-specific reproductive impairment through deregulation of different gene networks. More importantly, the observed epigenetic modifications induced by ionizing radiation are mediated through the alteration of chromatin remodeling and telomere function. This study, for the first time, demonstrated that ionizing radiation may alter the epigenome of germ cells, leading to transgenerational reproductive impairments, and correspondingly call for research in this new emerging area which remains almost unknown.

Genetic background determines renal response to chronic lithium treatment in female mice

Background Chronic lithium treatment for bipolar disease causes mainly side effects in the kidney. A subset of lithium users develops nephrogenic diabetes insipidus (NDI), a urinary concentrating disorder, and chronic kidney disease (CKD). Age, lithium dose and duration of treatment are important risk factors, while genetic background might also play an important role. Methods In order to investigate the role of genetics, female mice of 29 different inbred strains were treated for one year with control or lithium chow and urine, blood and kidneys were analysed. Results Chronic lithium treatment increased urine production and/or reduced urine osmolality in 21 strains. Renal histology showed that lithium increased interstitial fibrosis and/or tubular atrophy in eight strains, while in none of the strains glomerular injury was induced. Interestingly, lithium did not elevate urinary albumin-creatinine ratio (ACR) in any strain, while eight strains even demonstrated a lowered ACR. The protective effect on ACR coincided with a similar decrease in urinary IgG levels, a marker of glomerular function, while the adverse effect of lithium on interstitial fibrosis/tubular atrophy coincided with a severe increase in urinary β2-microglobulin (B2M) levels, an indicator of proximal tubule damage. Conclusion Genetic background plays an important role in the development of lithium-induced NDI and chronic renal pathology in female mice. The strong correlation of renal pathology with urinary B2M levels indicates B2M as a promising biomarker for chronic renal damage induced by lithium.

ERRγ, a new player in the type I IFN arena

Discussion on how the nuclear orphan receptor ERRγ induces type I IFNs and impacts the estrogenic response in host defense and disease progression.

PPARγ/PGC1α signaling as a potential therapeutic target for mitochondrial biogenesis in neurodegenerative disorders

Neurodegenerative diseases represent some of the most devastating neurological disorders, characterized by progressive loss of the structure and function of neurons. Current therapy for neurodegenerative disorders is limited to symptomatic treatment rather than disease modifying interventions, emphasizing the desperate need for improved approaches. Abundant evidence indicates that impaired mitochondrial function plays a crucial role in pathogenesis of many neurodegenerative diseases and so biochemical factors in mitochondria are considered promising targets for pharmacological-based therapies. Peroxisome proliferator-activated receptors-γ (PPARγ) are ligand-inducible transcription factors involved in regulating various genes including peroxisome proliferator-activated receptor gamma co-activator-1 alpha (PGC1α). This review summarizes the evidence supporting the ability of PPARγ-PGC1α to coordinately up-regulate the expression of genes required for mitochondrial biogenesis in neurons and provide directions for future work to explore the potential benefit of targeting mitochondrial biogenesis in neurodegenerative disorders. We have highlighted key roles of NRF2, uncoupling protein-2 (UCP2), and paraoxonase-2 (PON2) signaling in mediating PGC1α-induced mitochondrial biogenesis. In addition, the status of PPARγ modulators being used in clinical trials for Parkinson's disease (PD), Alzheimer's disease (AD) and Huntington's disease (HD) has been compiled. The overall purpose of this review is to update and critique our understanding of the role of PPARγ-PGC1α-NRF2 in the induction of mitochondrial biogenesis together with suggestions for strategies to target PPARγ-PGC1α-NRF2 signaling in order to combat mitochondrial dysfunction in neurodegenerative disorders.

Estrogen-related receptors: novel potential regulators of osteoarthritis pathogenesis

Osteoarthritis (OA) is a chronic inflammatory disease that is associated with articular cartilage destruction, subchondral bone alterations, synovitis, and even joint deformity and the loss of joint function. Although current basic research on the pathogenesis of OA has made remarkable progress, our understanding of this disease still needs to be further improved. Recent studies have shown that the estrogen-related receptor (ERR) family members ERRα and ERRγ may play significant roles in the pathogenesis of OA. In this review, we refer to the latest research on ERRs and the pathogenesis of OA, elucidate the structure and physiopathological functions of the ERR orphan nuclear receptor family, and systematically examine the relationship between ERRs and OA at the molecular level. Moreover, we also discuss and predict the capacity of ERRs as potential targets in the clinical treatment of OA.

A comprehensive review of the neurobehavioral effects of bisphenol S and the mechanisms of action: New insights from in vitro and in vivo models

The normal brain development and function are delicately driven by an ever-changing milieu of steroid hormones arising from fetal, placental, and maternal origins. This reliance on the neuroendocrine system sets the stage for the exquisite sensitivity of the central nervous system to the adverse effects of endocrine-disrupting chemicals (EDCs). Bisphenol A (BPA) is one of the most common EDCs which has been a particular focus of environmental concern for decades due to its widespread nature and formidable threat to human and animal health. The heightened regulatory actions and the scientific and public concern over the adverse health effects of BPA have led to its replacement with a suite of structurally similar but less known alternative chemicals. Bisphenol S (BPS) is the main substitute for BPA that is increasingly being used in a wide array of consumer and industrial products. Although it was considered to be a safe BPA alternative, mounting evidence points to the deleterious effects of BPS on a wide range of neuroendocrine functions in animals. In addition to its reproductive toxicity, recent experimental efforts indicate that BPS has a considerable potential to induce neurotoxicity and behavioral dysfunction. This review analyzes the current state of knowledge regarding the neurobehavioral effects of BPS and discusses its potential mode of actions on several aspects of the neuroendocrine system. We summarize the role of certain hormones and their signaling pathways in the regulation of brain and behavior and discuss how BPS induces neurotoxicity through interactions with these pathways. Finally, we review potential links between BPS exposure and aberrant neurobehavioral functions in animals and identify key knowledge gaps and hypotheses for future research.

Estrogen receptors α, β and GPER in the CNS and trigeminal system - molecular and functional aspects

BACKGROUND

Migraine occurs 2-3 times more often in females than in males and is in many females associated with the onset of menstruation. The steroid hormone, 17β-estradiol (estrogen, E2), exerts its effects by binding and activating several estrogen receptors (ERs). Calcitonin gene-related peptide (CGRP) has a strong position in migraine pathophysiology, and interaction with CGRP has resulted in several successful drugs for acute and prophylactic treatment of migraine, effective in all age groups and in both sexes.

METHODS

Immunohistochemistry was used for detection and localization of proteins, release of CGRP and PACAP investigated by ELISA and myography/perfusion arteriography was performed on rat and human arterial segments.

RESULTS

ERα was found throughout the whole brain, and in several migraine related structures. ERβ was mainly found in the hippocampus and the cerebellum. In trigeminal ganglion (TG), ERα was found in the nuclei of neurons; these neurons expressed CGRP or the CGRP receptor in the cytoplasm. G-protein ER (GPER) was observed in the cell membrane and cytoplasm in most TG neurons. We compared TG from males and females, and females expressed more ER receptors. For neuropeptide release, the only observable difference was a baseline CGRP release being higher in the pro-estrous state as compared to estrous state. In the middle cerebral artery (MCA), we observed similar dilatory ER-responses between males and females, except for vasodilatory ERβ which we observed only in female arteries.

CONCLUSION

These data reveal significant differences in ER receptor expression between male and female rats. This contrasts to CGRP and PACAP release where we did not observe discernable difference between the sexes. Together, this points to a hypothesis where estrogen could have a modulatory role on the trigeminal neuron function in general rather than on the acute CGRP release mechanisms and vasomotor responses.

Impact of estrogen receptor agonists and model of menopause on enzymes involved in brain metabolism, acetyl-CoA production and cholinergic function

Our goal is to understand how loss of circulating estrogens and estrogen replacement affect brain physiology and function, particularly in brain regions involved in cognitive processes. We recently conducted a large metabolomics study characterizing the effects of rodent models of menopause and treatment with estrogen receptor (ER) agonists on neurochemical targets in hippocampus, frontal cortex, and striatum. Here we characterize effects on levels of several key enzymes involved in glucose utilization and energy production, specifically phosphofructokinase, glyceraldehyde 3-phosphate dehydrogenase, and pyruvate dehydrogenase. We also evaluated effects on levels of β-actin and α-tubulin, choline acetyltransferase (ChAT) activity, and levels of ATP citrate lyase. All experiments were conducted in young adult rats. Experiment 1 compared the effects of ovariectomy (OVX), a model of surgical menopause, and 4-vinylcyclohexene diepoxide (VCD)-treatments, a model of transitional menopause, with tissues collected at proestrus and at diestrus. Experiment 2 used a separate cohort of rats to evaluate the same targets in OVX and VCD-treated rats treated with estradiol or with selective ER agonists. Differences in the expression of metabolic enzymes between cycling animals and models of surgical and transitional menopause were detected. These differences were model-, region- and time- dependent, and were modulated by selective ER agonists. Collectively, the findings demonstrate that loss of ovarian function and ER agonist treatments have differing effects in OVX vs. VCD-treated rats. Differences may help to explain differences in the effects of estrogen treatments on brain function and cognition in women who have experienced surgical vs. transitional menopause.

Mouse testicular transcriptome after modulation of non-canonical oestrogen receptor activity

The aims of this study were to shed light on the role of G-protein-coupled membrane oestrogen receptor (GPER) and oestrogen-related receptor (ERR) in mouse testis function at the gene expression level, as well as the involvement of GPER and ERR in cellular and molecular processes. Male mice were injected (50µg kg-1,s.c.) with the GPER antagonist G-15, the ERRα inverse agonist XCT790 or the ERRβ/ERRγ agonist DY131. Next-generation sequencing (RNA-Seq) was used to evaluate gene expression. Bioinformatic analysis of read abundance revealed that 50, 86 and 171 transcripts were differentially expressed in the G-15-, XCT790- and DY131-treated groups respectively compared with the control group. Annotated genes and their protein products were categorised regarding their associated biological processes and molecular functions. In the XCT790-treated group, genes involved in immunological processes were upregulated. In the DY131-treated group, genes with increased expression were primarily engaged in protein modification (protein folding and small protein conjugation). In addition, the expression of genes recognised as oncogenes, such as BMI1 proto-oncogene, polycomb ring finger (Bmi1) and nucleophosphin 1 (Npm1), was significantly increased in all experimental groups. This study provides detailed information regarding the genetic changes in the testicular transcriptome of the mouse in response to modulation of non-canonical oestrogen receptor activity.

Estrogen-Related Receptor Alpha: An Under-Appreciated Potential Target for the Treatment of Metabolic Diseases

The estrogen-related receptor alpha (ESRRA) is an orphan nuclear receptor (NR) that significantly influences cellular metabolism. ESRRA is predominantly expressed in metabolically-active tissues and regulates the transcription of metabolic genes, including those involved in mitochondrial turnover and autophagy. Although ESRRA activity is well-characterized in several types of cancer, recent reports suggest that it also has an important role in metabolic diseases. This minireview focuses on the regulation of cellular metabolism and function by ESRRA and its potential as a target for the treatment of metabolic disorders.

Depressive behavior induced by nonylphenol and its effect on the expression of ER-α and ER-β in nerve cells of rats

OBJECTIVE

To investigate the effects of nonylphenol (NP) exposure on the depressive behavior in rats, and the effects of the expressions of estrogen receptor-α (ER-α) and estrogen receptor-β (ER-β) in nerve cells in vivo and vitro.

METHODS

Forty male SD rats were randomly divided into 4 groups: blank control group (0 mg/kg), low dose group (0.4 mg/kg), middle dose group (4 mg/kg) and high dose group (40 mg/kg), which were exposed to NP for 180 days. The exposure dose of NP in HT22 was 20μM, which was divided into4 groups: blank control group, NP group, ICI182780 group and ICI182780+NP group.

RESULTS

In vivo, in the open field experiment, the number of entries in the central area and duration of attention in central square decreased gradually in the NP high dose group compared with the control (F = 3.561, p = .029). In forced swimming experiment, with the increase of NP dose, the immobility time increased, and the increasing degree of middle dose group and high dose group was higher than that of the low dose group (F = 3.047, p = .048). The concentrations of serum dopamine (DA) in the middle dose and high dose groups decreased greatly compared with the control (F = 3.967, p = .023). NP exposure at the doses of 4 mg/kg and 40 mg/kg induced an increase in the level of serum corticosterone compared to the control (F = 11.536, p<.001). Compared with the control group, the expression of ER-β decreased gradually with an increase of NP dose in the NP treatment groups (F = 4.513, p = .014). In vitro, the activity of HT22 cells decreased with an increase of NP dose (F = 316.6, p<.001). When the dose of NP was 200 μM, the growth inhibition rate of HT22 cells was (0.54±0.11)%. The expression levels of ER-α and ER-β in ICI182780+NP group was lower than those in the control and ICI182780 groups, but higher than those in the NP group (F = 1.592, p=.266; F = 10.166, p=.004).

CONCLUSION

Long-term exposure to NP could induce the alterations in depressive behavior, and the levels of neurotransmitters as well as the expression of ER in the hippocampus of rats. Moreover, NP could reduce the activity of HT22 cells and decrease the expression levels of ER-α and ER-β in vitro.

Identification, characterization and mRNA transcript abundance profiles of estrogen related receptor (ERR) in Sepiella japonica imply its possible involvement in female reproduction

Estrogen related receptors (ERRs) are widely detected in vertebrates and apparently have functions in reproduction. The functions of ERRs in reproduction of invertebrates, especially in mollusk cephalopods, are largely unknown. In the present study, An homologue of vertebrate ERR gene was first cloned from female Sepiella japonica, an important Cephalopod species in coastal water of China. Results indicate the S. japonica ERR (sjERR) gene is comprised of 1513 nucleotides, containing a 1389 bp open reading frame, which encode for 463 amino acid (aa) residues. The deduced sjERR protein possessed six typical nuclear receptors (NR) domains (A-F), with a DNA-binding domain (DBD) and a highly conserved ligand-binding domain (LBD), compared to the other molluscan ERRs. Results from tissue analyses indicated that sjERR mRNA transcript abundance was in largest amounts in tissues of the brain, liver, ovary that are possibly involved in reproduction. The sjERR mRNA transcript abundance was temporally regulated during the different sexual maturation phases of female S. japonica and was affected by in vivo administrations of vertebrate steroid estradiol-17β (E2). An in vivo knockdown of sjERR gene expression resulted in a marked down-regulation in expression of genes involved in ovarian development, such as Vitellogenin, CDK1, and Cyclin B, indicating there is a possible involvement of sjERR in reproduction. Both fusion protein transient transfections and immunohistochemical analyses indicated a presence of sjERR in the nucleus, implying a possible mechanism of action of the sjERR in the nucleus through activation of specific gene transcriptions.

Epilepsy Is Associated With Dysregulation of Long Non-coding RNAs in the Peripheral Blood

Background: Long non-coding RNAs (lncRNAs) are a group of functional transcripts that are not translated to proteins. Recent investigations have underscored their role in the pathogenesis of neurodevelopmental disorders.

Methods: In the current investigation, we quantified expression levels of four lncRNAs (HOXA-AS2, SPRY4-IT1, MEG3, and LINC-ROR) in peripheral blood of epileptic patients and normal controls.

Results: Expression of HOXA-AS2 was significantly higher in patients compared with controls (Posterior beta = 1.982, P = 0.001). We detected interaction effects of gender on expression of HOXA-AS2 (P = 0.012). Further analyses showed over-expression of HOXA-AS2 in male patients compared with male controls (P = 0.003), in spite of similar levels of expression between female cases and female controls (P = 0.77). Expression of SPRY4-IT1 was higher in total patients compared with total controls (Posterior beta = 1.27, P = 0.02). Such difference was only observed between male patients and male controls when dividing study participants based on their gender (P = 0.012). There was no significant difference in expression of MEG3 and LINC-ROR between patients and controls.

Conclusion: Expression levels of all lncRNAs were correlated with each other with r values ranging from 0.61 to 0.76 (P < 0.0001). However, expressions of none of lncRNAs were correlated with age of study participants. The current data implies a putative role for two lncRNAs in the pathogenesis of epilepsy and warrants future functional studies to verify the observed association.

Synaptic plasticity in hippocampal CA1 neurons and learning behavior in acute kidney injury, and estradiol replacement in ovariectomized rats

Background

Neurological complications may occur in patients with acute or chronic renal failure; however, in cases of acute renal failure, the signs and symptoms are usually more pronounced, and progressed rapidly. Oxidative stress and nitric oxide in the hippocampus, following kidney injury may be involved in cognitive impairment in patients with uremia. Although many women continue taking hormone therapy for menopausal symptom relief, but there are also some controversies about the efficacy of exogenous sex hormones, especially estrogen therapy alone, in postmenopausal women with kidney injury. Herein, to the best of our knowledge for the first time, spatial memory and synaptic plasticity at the CA1 synapse of a uremic ovariectomized rat model of menopause was characterized by estradiol replacement alone.

Results

While estradiol replacement in ovariectomized rats without uremia, promotes synaptic plasticity, it has an impairing effect on spatial memory through hippocampal oxidative stress under uremic conditions, with no change on synaptic plasticity. It seems that exogenous estradiol potentiated the deleterious effect of acute kidney injury (AKI) with increasing hippocampal oxidative stress.

Conclusions

Although, estrogen may have some positive effects on cognitive function in healthy subjects, but its efficacy in menopause subjects under uremic states such as renal transplantation, needs to be further investigated in terms of dosage and duration.

Sex hormones and their influence on chronic kidney disease

PURPOSE OF REVIEW

The majority of end-stage renal disease including dialysis and kidney transplant patients are men. In contrast, the incidence of chronic kidney disease (CKD) is higher in women compared with men. In this review, we dissect the sex hormone levels and its effects on experimental models and patients with CKD.

RECENT FINDINGS

Sex hormones are clearly involved in CKD progression to end-stage renal disease (ESRD). A significant reduction in lipid peroxidation as a mechanism of renoprotection has been observed in kidneys of streptozotocin (STZ)-diabetic ovariectomized rats after estradiol administration. Furthermore, a G-protein-coupled estrogen receptor inhibits podocyte oxidative stress maintaining the integrity of the mitochondrial membrane. Sex hormone depletion has been shown to modulate RAS system and protect against kidney injury in the male STZ-diabetic model. In human primary proximal tubular epithelial cells, a proteomic study showed that dihydrotestosterone dysregulated metabolic, suggesting that the deleterious effect of androgens within the kidney maybe related to altered energy metabolism in renal tubules.

SUMMARY

Male gender is associated with worse CKD progression and this fact may be ascribed to sex hormone. Although male hormones exert a deleterious effect in terms of increasing oxidative stress, activating RAS system, and worsening fibrosis within the damaged kidney, female hormones exert a renoprotective effect.

Potential roles of nuclear receptors in mediating neurodevelopmental toxicity of known endocrine-disrupting chemicals in ascidian embryos

Endocrine Disrupting Chemicals (EDCs) are molecules able to interfere with the vertebrate hormonal system in different ways, a major one being the modification of the activity of nuclear receptors (NRs). Several NRs are expressed in the vertebrate brain during embryonic development and these NRs are suspected to be responsible for the neurodevelopmental defects induced by exposure to EDCs in fishes or amphibians and to participate in several neurodevelopmental disorders observed in humans. Known EDCs exert toxicity not only on vertebrate forms of marine life but also on marine invertebrates. However, because hormonal systems of invertebrates are poorly understood, it is not clear whether the teratogenic effects of known EDCs are because of endocrine disruption. The most conserved actors of endocrine systems are the NRs which are present in all metazoan genomes but their functions in invertebrate organisms are still insufficiently characterized. EDCs like bisphenol A have recently been shown to affect neurodevelopment in marine invertebrate chordates called ascidians. Because such phenotypes can be mediated by NRs expressed in the ascidian embryo, we review all the information available about NRs expression during ascidian embryogenesis and discuss their possible involvement in the neurodevelopmental phenotypes induced by EDCs.

Sex differences in hearing: Probing the role of estrogen signaling

Hearing loss is the most common form of sensory impairment in humans, with an anticipated rise in incidence as the result of recreational noise exposures. Hearing loss is also the second most common health issue afflicting military veterans. Currently, there are no approved therapeutics to treat sensorineural hearing loss in humans. While hearing loss affects both men and women, sexual dimorphism is documented with respect to peripheral and central auditory physiology, as well as susceptibility to age-related and noise-induced hearing loss. Physiological differences between the sexes are often hormone-driven, and an increasing body of literature demonstrates that the hormone estrogen and its related signaling pathways may in part, modulate the aforementioned differences in hearing. From a mechanistic perspective, understanding the underpinnings of the hormonal modulation of hearing may lead to the development of therapeutics for age related and noise induced hearing loss. Here the authors review a number of studies that range from human populations to animal models, which have begun to provide a framework for understanding the functional role of estrogen signaling in hearing, particularly in normal and aberrant peripheral auditory physiology.

Sex hormones modulate pathogenic processes in experimental traumatic brain injury

Clinical and animal studies have revealed sex-specific differences in histopathological and neurological outcome after traumatic brain injury (TBI). The impact of perioperative administration of sex steroid inhibitors on TBI is still elusive. Here, we subjected male and female C57Bl/6N mice to the controlled cortical impact (CCI) model of TBI and applied pharmacological inhibitors of steroid hormone synthesis, that is, letrozole (LET, inhibiting estradiol synthesis by aromatase) and finasteride (FIN, inhibiting dihydrotestosterone synthesis by 5α-reductase), respectively, starting 72 h prior CCI, and continuing for a further 48 h after CCI. Initial gene expression analyses showed that androgen (Ar) and estrogen receptors (Esr1) were sex-specifically altered 72 h after CCI. When examining brain lesion size, we found larger lesions in male than in female mice, but did not observe effects of FIN or LET treatment. However, LET treatment exacerbated neurological deficits 24 and 72 h after CCI. On the molecular level, FIN administration reduced calpain-dependent spectrin breakdown products, a proxy of excitotoxicity and disturbed Ca²⁺ homeostasis, specifically in males, whereas LET increased the reactive astrocyte marker glial fibrillary acid protein specifically in females. Examination of neurotrophins (brain-derived neurotrophic factor, neuronal growth factor, NT-3) and their receptors (p75^NTR , TrkA, TrkB, TrkC) revealed CCI-induced down-regulation of TrkB and TrkC protein expression, which was reduced by LET in both sexes. Interestingly, FIN decreased neuronal growth factor mRNA expression and protein levels of its receptor TrkA only in males. Taken together, our data suggest a sex-specific impact on pathogenic processes in the injured brain after TBI. Sex hormones may thus modulate pathogenic processes in experimental TBI.