Membrane-initiated estrogen signaling via Gq-coupled GPCR in the central nervous system

Effect of hyperoside on osteoporosis in ovariectomized mice through estrogen receptor α/ITGβ3 signaling pathway

Osteoporosis is a highly prevalent bone metabolic disease in menopause due to estrogen deficiency. Hyperoside is a main compound in Semen cuscutae. Our team previously reported that Semen cuscutae has anti osteoporosis effect on ovariectomized mice by inhibiting bone resorption of osteoclasts. However, it is still unclear whether hyperoside affects osteoclast differentiation and bone resorption, and whether its anti-osteoporosis effect is related to an estrogen-like effect. This study investigates the potential mechanism of hyperoside's anti-osteoporotic effect by examining its impact on osteoclast differentiation and its relationship with the estrogen receptor. DXA, Micro-CT, TRAP staining, HE, and ELISA were used to assess the impact of hyperoside on OVX-induced osteoporosis. The effect of hyperoside on octeoclast differentiation was evaluated using TRAP activity assay, TRAP staining, F-actin staining. The activation of the estrogen receptor by hyperoside and its relationship with osteoclast differentiation were detected using dual-luciferase reporter assay and estrogen receptor antagonists. Our findings revealed that hyperoside (20-80 mg/kg) protect against OVX-induced osteoporosis, including increasing BMD and BMC and improving bone microstructure. Hyperoside inhibited osteoclast differentiation in a concentration dependent manner, whereas estrogen receptor α antagonists reversed its inhibitory effect osteoclast differentiation. Western blot results suggested that hyperoside inhibited TRAP, RANKL, c-Fos and ITG β3 protein expression in osteoclast or femoral bone marrow of ovariectomized mice. Our findings suggest that hyperoside inhibits osteoclast differentiation and protects OVX-induced osteoporosis through the ERα/ITGβ3 signaling pathway.

Sex-specific role of high-fat diet and stress on behavior, energy metabolism, and the ventromedial hypothalamus

BACKGROUND

Scientific evidence highlights the influence of biological sex on the relationship between stress and metabolic dysfunctions. However, there is limited understanding of how diet and stress concurrently contribute to metabolic dysregulation in both males and females. Our study aimed to investigate the combined effects of high-fat diet (HFD) induced obesity and repeated stress on fear-related behaviors, metabolic, immune, and hypothalamic outcomes in male and female mice.

METHODS

To investigate this, we used a highly reliable rodent behavioral model that faithfully recapitulates key aspects of post-traumatic stress disorder (PTSD)-like fear. We subjected mice to footshock stressor followed by a weekly singular footshock stressor or no stressor for 14 weeks while on either an HFD or chow diet. At weeks 10 and 14 we conducted glucose tolerance and insulin sensitivity measurements. Additionally, we placed the mice in metabolic chambers to perform indirect calorimetric measurements. Finally, we collected brain and peripheral tissues for cellular analysis.

RESULTS

We observed that HFD-induced obesity disrupted fear memory extinction, increased glucose intolerance, and affected energy expenditure specifically in male mice. Conversely, female mice on HFD exhibited reduced respiratory exchange ratio (RER), and a significant defect in glucose tolerance only when subjected to repeated stress. Furthermore, the combination of repeated stress and HFD led to sex-specific alterations in proinflammatory markers and hematopoietic stem cells across various peripheral metabolic tissues. Single-nuclei RNA sequencing (snRNAseq) analysis of the ventromedial hypothalamus (VMH) revealed microglial activation in female mice on HFD, while male mice on HFD exhibited astrocytic activation under repeated stress.

CONCLUSIONS

Overall, our findings provide insights into complex interplay between repeated stress, high-fat diet regimen, and their cumulative effects on health, including their potential contribution to the development of PTSD-like stress and metabolic dysfunctions, emphasizing the need for further research to fully understand these interconnected pathways and their implications for health.

Sex as a Determinant of Age-Related Changes in the Brain

The notion of notable anatomical, biochemical, and behavioral distinctions within male and female brains has been a contentious topic of interest within the scientific community over several decades. Advancements in neuroimaging and molecular biological techniques have increasingly elucidated common mechanisms characterizing brain aging while also revealing disparities between sexes in these processes. Variations in cognitive functions; susceptibility to and progression of neurodegenerative conditions, notably Alzheimer's and Parkinson's diseases; and notable disparities in life expectancy between sexes, underscore the significance of evaluating aging within the framework of gender differences. This comprehensive review surveys contemporary literature on the restructuring of brain structures and fundamental processes unfolding in the aging brain at cellular and molecular levels, with a focus on gender distinctions. Additionally, the review delves into age-related cognitive alterations, exploring factors influencing the acceleration or deceleration of aging, with particular attention to estrogen's hormonal support of the central nervous system.

Insights into neurosteroids and their role in women with epilepsy

Epilepsy, is a serious neurological condition, characterized by recurring, unprovoked seizures and affects over 50 million people worldwide. Epilepsy has an equal prevalence in males and females, and occurs throughout the life span. Women with epilepsy (WWE) present with unique challenges due to the cyclical fluctuation of sex steroid hormone concentrations during their life course. These shifts in sex steroid hormones and their metabolites are intricately intertwined with seizure susceptibility and affect epilepsy during the life course of women in a complex manner. Here we present a review encompassing neurosteroids-steroids that act on the brain regardless of their site of synthesis in the body; the role of neurosteroids in women with epilepsy through their life-course; exogenous neurosteroid trials; and future research directions. The focus of this review is on progesterone and its derived neurosteroids, given the extensive basic research that supports their role in modulating neuronal excitability.

Optimization of small molecule degraders and antagonists for targeting estrogen receptor based on breast cancer: current status and future

The estrogen receptor (ER) is a classical receptor protein that plays a crucial role in mediating multiple signaling pathways in various target organs. It has been shown that ER-targeting therapies inhibit breast cancer cell proliferation, enhance neuronal protection, and promote osteoclast formation. Several drugs have been designed to specifically target ER in ER-positive (ER+) breast cancer, including selective estrogen receptor modulators (SERM) such as Tamoxifen. However, the emergence of drug resistance in ER+ breast cancer and the potential side effects on the endometrium which has high ER expression has posed significant challenges in clinical practice. Recently, novel ER-targeted drugs, namely, selective estrogen receptor degrader (SERD) and selective estrogen receptor covalent antagonist (SERCA) have shown promise in addressing these concerns. This paper provides a comprehensive review of the structural functions of ER and highlights recent advancements in SERD and SERCA-related small molecule drugs, especially focusing on their structural optimization strategies and future optimization directions. Additionally, the therapeutic potential and challenges of novel SERDs and SERCAs in breast cancer and other ER-related diseases have been discussed.

BNST PKCδ neurons are activated by specific aversive conditions to promote anxiety-like behavior

The bed nucleus of the stria terminalis (BNST) is a critical mediator of stress responses and anxiety-like behaviors. Neurons expressing protein kinase C delta (BNSTPKCδ) are an abundant but understudied subpopulation implicated in inhibiting feeding, but which have conflicting reports about their role in anxiety-like behaviors. We have previously shown that expression of PKCδ is dynamically regulated by stress and that BNSTPKCδ cells are recruited during bouts of active stress coping. Here, we first show that in vivo activation of this population is mildly aversive. This aversion was insensitive to prior restraint stress exposure. Further investigation revealed that unlike other BNST subpopulations, BNSTPKCδ cells do not exhibit increased cfos expression following restraint stress. Ex vivo current clamp recordings also indicate they are resistant to firing. To elucidate their afferent control, we next used rabies tracing with whole-brain imaging and channelrhodopsin-assisted circuit mapping, finding that BNSTPKCδ cells receive abundant input from affective, arousal, and sensory regions including the basolateral amygdala (BLA) paraventricular thalamus (PVT) and central amygdala PKCδ-expressing cells (CeAPKCδ). Given these findings, we used in vivo optogenetics and fiber photometry to further examine BNSTPKCδ cells in the context of stress and anxiety-like behavior. We found that BNSTPKCδ cell activity is associated with increased anxiety-like behavior in the elevated plus maze, increases following footshock, and unlike other BNST subpopulations, does not desensitize to repeated stress exposure. Taken together, we propose a model in which BNSTPKCδ cells may serve as threat detectors, integrating exteroceptive and interoceptive information to inform stress coping behaviors.

Emerging Evidence on Membrane Estrogen Receptors as Novel Therapeutic Targets for Central Nervous System Pathologies

Nuclear- and membrane-initiated estrogen signaling cooperate to orchestrate the pleiotropic effects of estrogens. Classical estrogen receptors (ERs) act transcriptionally and govern the vast majority of hormonal effects, whereas membrane ERs (mERs) enable acute modulation of estrogenic signaling and have recently been shown to exert strong neuroprotective capacity without the negative side effects associated with nuclear ER activity. In recent years, GPER1 was the most extensively characterized mER. Despite triggering neuroprotective effects, cognitive improvements, and vascular protective effects and maintaining metabolic homeostasis, GPER1 has become the subject of controversy, particularly due to its participation in tumorigenesis. This is why interest has recently turned toward non-GPER-dependent mERs, namely, mERα and mERβ. According to available data, non-GPER-dependent mERs elicit protective effects against brain damage, synaptic plasticity impairment, memory and cognitive dysfunctions, metabolic imbalance, and vascular insufficiency. We postulate that these properties are emerging platforms for designing new therapeutics that may be used in the treatment of stroke and neurodegenerative diseases. Since mERs have the ability to interfere with noncoding RNAs and to regulate the translational status of brain tissue by affecting histones, non-GPER-dependent mERs appear to be attractive targets for modern pharmacotherapy for nervous system diseases.

Centering the Needs of Transgender, Nonbinary, and Gender-Diverse Populations in Neuroendocrine Models of Gender-Affirming Hormone Therapy

Most studies attempting to address the health care needs of the millions of transgender, nonbinary, and/or gender-diverse (TNG) individuals rely on human subjects, overlooking the benefits of translational research in animal models. Researchers have identified many ways in which gonadal steroid hormones regulate neuronal gene expression, connectivity, activity, and function across the brain to control behavior. However, these discoveries primarily benefit cisgender populations. Research into the effects of exogenous hormones such as estradiol, testosterone, and progesterone has a direct translational benefit for TNG individuals on gender-affirming hormone therapies (GAHTs). Despite this potential, endocrinological health care for TNG individuals remains largely unimproved. Here, we outline important areas of translational research that could address the unique health care needs of TNG individuals on GAHT. We highlight key biomedical questions regarding GAHT that can be investigated using animal models. We discuss how contemporary research fails to address the needs of GAHT users and identify equitable practices for cisgender scientists engaging with this work. We conclude that if necessary and important steps are taken to address these issues, translational research on GAHTs will greatly benefit the health care outcomes of TNG people.

Zinc's Association with the CmPn/CmP Signaling Network in Breast Cancer Tumorigenesis

It is well-known that serum and cellular concentrations of zinc are altered in breast cancer patients. Specifically, there are notable zinc hyper-aggregates in breast tumor cells when compared to normal mammary epithelial cells. However, the mechanisms responsible for zinc accumulation and the consequences of zinc dysregulation are poorly understood. In this review, we detailed cellular zinc regulation/dysregulation under the influence of varying levels of sex steroids and breast cancer tumorigenesis to try to better understand the intricate relationship between these factors based on our current understanding of the CmPn/CmP signaling network. We also made some efforts to propose a relationship between zinc signaling and the CmPn/CmP signaling network.

Estrogens rapidly shape synaptic and intrinsic properties to regulate the temporal precision of songbird auditory neurons

Sensory neurons parse millisecond-variant sound streams like birdsong and speech with exquisite precision. The auditory pallial cortex of vocal learners like humans and songbirds contains an unconventional neuromodulatory system: neuronal expression of the estrogen synthesis enzyme aromatase. Local forebrain neuroestrogens fluctuate when songbirds hear a song, and subsequently modulate bursting, gain, and temporal coding properties of auditory neurons. However, the way neuroestrogens shape intrinsic and synaptic properties of sensory neurons remains unknown. Here, using a combination of whole-cell patch clamp electrophysiology and calcium imaging, we investigate estrogenic neuromodulation of auditory neurons in a region resembling mammalian auditory association cortex. We found that estradiol rapidly enhances the temporal precision of neuronal firing via a membrane-bound G-protein coupled receptor and that estradiol rapidly suppresses inhibitory synaptic currents while sparing excitation. Notably, the rapid suppression of intrinsic excitability by estradiol was predicted by membrane input resistance and was observed in both males and females. These findings were corroborated by analysis of in vivo electrophysiology recordings, in which local estrogen synthesis blockade caused acute disruption of the temporal correlation of song-evoked firing patterns. Therefore, on a modulatory timescale, neuroestrogens alter intrinsic cellular properties and inhibitory neurotransmitter release to regulate the temporal precision of higher-order sensory neurons.

The estrous cycle and 17β-estradiol modulate the electrophysiological properties of rat nucleus accumbens core medium spiny neurons

The nucleus accumbens core is a key nexus within the mammalian brain for integrating the premotor and limbic systems and regulating important cognitive functions such as motivated behaviors. Nucleus accumbens core functions show sex differences and are sensitive to the presence of hormones such as 17β-estradiol (estradiol) in normal and pathological contexts. The primary neuron type of the nucleus accumbens core, the medium spiny neuron (MSN), exhibits sex differences in both intrinsic excitability and glutamatergic excitatory synapse electrophysiological properties. Here, we provide a review of recent literature showing how estradiol modulates rat nucleus accumbens core MSN electrophysiology within the context of the estrous cycle. We review the changes in MSN electrophysiological properties across the estrous cycle and how these changes can be mimicked in response to exogenous estradiol exposure. We discuss in detail recent findings regarding how acute estradiol exposure rapidly modulates excitatory synapse properties in nucleus accumbens core but not caudate-putamen MSNs, which mirror the natural changes seen across estrous cycle phases. These recent insights demonstrate the strong impact of sex-specific estradiol action upon nucleus accumbens core neuron electrophysiology.

The hypothalamic paraventricular nucleus as a central hub for the estrogenic modulation of neuroendocrine function and behavior

Estradiol and hypothalamic paraventricular nucleus (PVN) help coordinate reproduction with body physiology, growth and metabolism. PVN integrates hormonal and neural signals originating in the periphery, generating an output mediated both by its long-distance neuronal projections, and by a variety of neurohormones produced by its magnocellular and parvocellular neurosecretory cells. Here we review the cyto-and chemo-architecture, the connectivity and function of PVN and the sex-specific regulation exerted by estradiol on PVN neurons and on the expression of neurotransmitters, neuromodulators, neuropeptides and neurohormones in PVN. Classical and non-classical estrogen receptors (ERs) are expressed in neuronal afferents to PVN and in specific PVN interneurons, projecting neurons, neurosecretory neurons and glial cells that are involved in the input-output integration and coordination of neurohormonal signals. Indeed, PVN ERs are known to modulate body homeostatic processes such as autonomic functions, stress response, reproduction, and metabolic control. Finally, the functional implications of the estrogenic modulation of the PVN for body homeostasis are discussed.

Neural mechanisms of persistent aggression

While aggression is often conceptualized as a highly stereotyped, innate behavior, individuals within a species exhibit a surprising amount of variability in the frequency, intensity, and targets of their aggression. While differences in genetics are a source of some of this variation across individuals (estimates place the heritability of behavior at around 25-30%), a critical driver of variability is previous life experience. A wide variety of social experiences, including sexual, parental, and housing experiences can facilitate "persistent" aggressive states, suggesting that these experiences engage a common set of synaptic and molecular mechanisms that act on dedicated neural circuits for aggression. It has long been known that sex steroid hormones are powerful modulators of behavior, and also, that levels of these hormones are themselves modulated by experience. Several recent studies have started to unravel how experience-dependent hormonal changes during adulthood can create a cascade of molecular, synaptic, and circuit changes that enable behavioral persistence through circuit level remodeling. Here, we propose that sex steroid hormones facilitate persistent aggressive states by changing the relationship between neural activity and an aggression "threshold".

Membrane-initiated actions of sex steroids and reproductive behavior: A historical account

It was assumed for a long time that sex steroids are activating reproductive behaviors by the same mechanisms that produce their morphological and physiological effects in the periphery. However during the last few decades an increasing number of examples were identified where behavioral effects of steroids were just too fast to be mediated via changes in DNA transcription. This progressively forced behavioral neuroendocrinologists to recognize that part of the effects of steroids on behavior are mediated by membrane-initiated events. In this review we present a selection of these early data that changed the conceptual landscape and we provide a summary the different types of membrane-associated receptors (estrogens, androgens and progestagens receptors) that are playing the most important role in the control of reproductive behaviors. Then we finally describe in more detail three separate behavioral systems in which membrane-initiated events have clearly been established to contribute to behavior control.

The influence of estrogen receptor α signaling independent of the estrogen response element on avoidance behavior, social interactions, and palatable ingestive behavior in female mice

Women are vulnerable to developing mental disorders that are associated with circulating estrogens. Estrogens, especially 17β-estradiol (E2), have a wide array of effects on the brain, affecting many behavioral endpoints associated with mental illness. By using a total estrogen receptor (ER) α knockout (KO), an ERα knock in/knock out (KIKO) that lacks a functional DNA-binding domain, and wild type (WT) controls treated with either oil or E2, we evaluated ERα signaling, dependent and independent of the estrogen response element (ERE), on avoidance behavior, social interactions and memory, and palatable ingestive behavior using the open field test, the elevated plus maze, the light dark box, the 3-chamber test, and palatable feeding. We found that ERα does not mediate control of anxiety-like behaviors but rather yielded differences in locomotor activity. In evaluating social preference and social recognition memory, we observed that E2 may modulate these measures in KIKO females but not KO females, suggesting that ERE-independent signaling is likely involved in sociability. Lastly, observations of palatable (high-fat) food intake suggested an increase in palatable eating behavior in oil-treated KIKO females. Oil-treated KO females had a longer latency to food intake, indicative of an anhedonic phenotype compared to oil-treated WT and KIKO females. We have observed that social-related behaviors are potentially influenced by ERE-independent ERα signaling and hedonic food intake requires signaling of ERα.

From Menopause to Neurodegeneration-Molecular Basis and Potential Therapy

The impacts of menopause on neurodegenerative diseases, especially the changes in steroid hormones, have been well described in cell models, animal models, and humans. However, the therapeutic effects of hormone replacement therapy on postmenopausal women with neurodegenerative diseases remain controversial. The steroid hormones, steroid hormone receptors, and downstream signal pathways in the brain change with aging and contribute to disease progression. Estrogen and progesterone are two steroid hormones which decline in circulation and the brain during menopause. Insulin-like growth factor 1 (IGF-1), which plays an import role in neuroprotection, is rapidly decreased in serum after menopause. Here, we summarize the actions of estrogen, progesterone, and IGF-1 and their signaling pathways in the brain. Since the incidence of Alzheimer’s disease (AD) is higher in women than in men, the associations of steroid hormone changes and AD are emphasized. The signaling pathways and cellular mechanisms for how steroid hormones and IGF-1 provide neuroprotection are also addressed. Finally, the molecular mechanisms of potential estrogen modulation on N-methyl-d-aspartic acid receptors (NMDARs) are also addressed. We provide the viewpoint of why hormone therapy has inconclusive results based on signaling pathways considering their complex response to aging and hormone treatments. Nonetheless, while diagnosable AD may not be treatable by hormone therapy, its preceding stage of mild cognitive impairment may very well be treatable by hormone therapy.

Role of Neuroglobin in the Neuroprotective Actions of Estradiol and Estrogenic Compounds

Estradiol exerts neuroprotective actions that are mediated by the regulation of a variety of signaling pathways and homeostatic molecules. Among these is neuroglobin, which is upregulated by estradiol and translocated to the mitochondria to sustain neuronal and glial cell adaptation to injury. In this paper, we will discuss the role of neuroglobin in the neuroprotective mechanisms elicited by estradiol acting on neurons, astrocytes and microglia. We will also consider the role of neuroglobin in the neuroprotective actions of clinically relevant synthetic steroids, such as tibolone. Finally, the possible contribution of the estrogenic regulation of neuroglobin to the generation of sex differences in brain pathology and the potential application of neuroglobin as therapy against neurological diseases will be examined.

Molecular Targets and Biological Functions of cAMP Signaling in Arabidopsis

Cyclic AMP (cAMP) is a pivotal signaling molecule existing in almost all living organisms. However, the mechanism of cAMP signaling in plants remains very poorly understood. Here, we employ the engineered activity of soluble adenylate cyclase to induce cellular cAMP elevation in Arabidopsis thaliana plants and identify 427 cAMP-responsive genes (CRGs) through RNA-seq analysis. Induction of cellular cAMP elevation inhibits seed germination, disturbs phytohormone contents, promotes leaf senescence, impairs ethylene response, and compromises salt stress tolerance and pathogen resistance. A set of 62 transcription factors are among the CRGs, supporting a prominent role of cAMP in transcriptional regulation. The CRGs are significantly overrepresented in the pathways of plant hormone signal transduction, MAPK signaling, and diterpenoid biosynthesis, but they are also implicated in lipid, sugar, K⁺, nitrate signaling, and beyond. Our results provide a basic framework of cAMP signaling for the community to explore. The regulatory roles of cAMP signaling in plant plasticity are discussed.

The Impact of Estrogen and Estrogen-Like Molecules in Neurogenesis and Neurodegeneration: Beneficial or Harmful?

Estrogens and estrogen-like molecules can modify the biology of several cell types. Estrogen receptors alpha (ERα) and beta (ERβ) belong to the so-called classical family of estrogen receptors, while the G protein-coupled estrogen receptor 1 (GPER-1) represents a non-classical estrogen receptor mainly located in the plasma membrane. As estrogen receptors are ubiquitously distributed, they can modulate cell proliferation, differentiation, and survival in several tissues and organs, including the central nervous system (CNS). Estrogens can exert neuroprotective roles by acting as anti-oxidants, promoting DNA repair, inducing the expression of growth factors, and modulating cerebral blood flow. Additionally, estrogen-dependent signaling pathways are involved in regulating the balance between proliferation and differentiation of neural stem/progenitor cells (NSPCs), thus influencing neurogenic processes. Since several estrogen-based therapies are used nowadays and estrogen-like molecules, including phytoestrogens and xenoestrogens, are omnipresent in our environment, estrogen-dependent changes in cell biology and tissue homeostasis have gained attention in human health and disease. This article provides a comprehensive literature review on the current knowledge of estrogen and estrogen-like molecules and their impact on cell survival and neurodegeneration, as well as their role in NSPCs proliferation/differentiation balance and neurogenesis.

The Complex Interplay between Endocannabinoid System and the Estrogen System in Central Nervous System and Periphery

The endocannabinoid system (ECS) is a lipid cell signaling system involved in the physiology and homeostasis of the brain and peripheral tissues. Synaptic plasticity, neuroendocrine functions, reproduction, and immune response among others all require the activity of functional ECS, with the onset of disease in case of ECS impairment. Estrogens, classically considered as female steroid hormones, regulate growth, differentiation, and many other functions in a broad range of target tissues and both sexes through the activation of nuclear and membrane estrogen receptors (ERs), which leads to genomic and non-genomic cell responses. Since ECS function overlaps or integrates with many other cell signaling systems, this review aims at updating the knowledge about the possible crosstalk between ECS and estrogen system (ES) at both central and peripheral level, with focuses on the central nervous system, reproduction, and cancer.

G protein-coupled receptors function as cell membrane receptors for the steroid hormone 20-hydroxyecdysone

Abstract

G protein-coupled receptors (GPCRs) are cell membrane receptors for various ligands. Recent studies have suggested that GPCRs transmit animal steroid hormone signals. Certain GPCRs have been shown to bind steroid hormones, for example, G protein-coupled estrogen receptor 1 (GPER1) binds estrogen in humans, and Drosophila dopamine/ecdysteroid receptor (DopEcR) binds the molting hormone 20-hydroxyecdysone (20E) in insects. This review summarizes the research progress on GPCRs as animal steroid hormone cell membrane receptors, including the nuclear and cell membrane receptors of steroid hormones in mammals and insects, the 20E signaling cascade via GPCRs, termination of 20E signaling, and the relationship between genomic action and the nongenomic action of 20E. Studies indicate that 20E induces a signal via GPCRs to regulate rapid cellular responses, including rapid Ca²⁺ release from the endoplasmic reticulum and influx from the extracellular medium, as well as rapid protein phosphorylation and subcellular translocation. 20E via the GPCR/Ca²⁺/PKC/signaling axis and the GPCR/cAMP/PKA-signaling axis regulates gene transcription by adjusting transcription complex formation and DNA binding activity. GPCRs can bind 20E in the cell membrane and after being isolated, suggesting GPCRs as cell membrane receptors of 20E. This review deepens our understanding of GPCRs as steroid hormone cell membrane receptors and the GPCR-mediated signaling pathway of 20E (20E-GPCR pathway), which will promote further study of steroid hormone signaling via GPCRs, and presents GPCRs as targets to explore new pharmaceutical materials to treat steroid hormone-related diseases or control pest insects.

Rapid membrane effect of estrogens on stimulation of corticotropin-releasing hormone

BACKGROUND

Classic nuclear-initiated estrogen signaling stimulates corticotropin-releasing hormone (CRH) gene expression as a transcription factor. However, the possible mechanism by which membrane-initiated estrogen signaling (MIES) influences CRH expression remains unclear. There are indications that MIES may upregulate nitric oxide (NO) production through the phosphatidylinositol 3-hydroxy kinase (PI3K) and potentially through the mitogen-activated protein kinase (MAPK) pathway.

OBJECTIVES

We investigated the effect of MIES-mediated kinase pathways on CRH expression with or without NO synthesis.

METHOD

In SK-N-SH cell culture, estradiol-bovine serum albumin (E2-BSA) was used as the specific membrane estrogen receptor activator, with a specific NO donor, and/or inhibitors for NO synthase (NOS), PI3K, MAPK, protein kinase A (PKA), and protein kinase C (PKC).

RESULTS

E2-BSA significantly increased NO and CRH levels in the medium and NOS1-mRNA levels in the cells. In addition, NO donor up-regulated CRH expression, while NOS-inhibitor down-regulated it. When the inhibitor of MAPK and/or the inhibitor of PI3K was added to the medium, only the latter appeared to significantly block the stimulating effect of E2-BSA on NO synthesis, and this was accompanied by an increased CRH expression in the medium. We further studied the effect of the MIES-PKC-mediated pathway on CRH expression, with or without NOS-inhibitor, while the MIES-PKA(-PI3K) pathway served as a control. We found that MIES-PKC upregulated CRH expression independent of NO synthesis.

CONCLUSION

MIES can efficiently upregulate CRH expression via various intracellular kinase pathways and may thus be a crucial component in the stress response.

Metabotropic glutamate receptor subtype 5 (mGlu5) is necessary for estradiol mitigation of light-induced anxiety behavior in female rats

Anxiety-related behaviors are influenced by steroid hormones such as 17β-estradiol and environmental stimuli such as acute stressors. For example, rats exhibit increased anxiety-related behaviors in the presence, but not the absence, of light. In females, estradiol potentially mitigates these effects. Experiments across behavioral paradigms and brain regions indicate that estradiol action can be mediated via activation of metabotropic glutamate receptors, including Group I subtype five (mGlu₅). mGlu₅ has been implicated in mediating estradiol's effects upon psychostimulant-induced behaviors, dopamine release and neuron phenotype in striatal regions. Whether estradiol activation of mGlu₅ modulates anxiety or locomotor behavior in the absence of psychostimulants is unknown. Here we test if mGlu₅ is necessary for estradiol mitigation of light-induced acute anxiety and locomotor behaviors. Ovariectomized adult female rats were pre-treated with either the mGlu₅ antagonist MPEP or saline before estradiol or oil treatment. Anxiety and locomotor behaviors were assessed in the presence or absence of white light to induce high and low acute anxiety behavior phenotypes, respectively. In the presence of white light, estradiol treatment mitigated light-induced anxiety-related behaviors but not overall locomotor activity. MPEP treatment blocked estradiol effects upon light-induced anxiety-related behaviors but did not affect overall locomotor activity. In the absence of white light, estradiol or MPEP treatment did not influence anxiety-related behaviors or locomotor activity, consistent with a low anxiety phenotype. These novel findings indicate that mGlu₅ activation is necessary for estradiol mitigation of anxiety-related behaviors induced by an acute stressor.

Protein kinase inhibitors infused intraventricularly or into the ventromedial hypothalamus block short latency facilitation of lordosis by oestradiol

An injection of unesterified oestradiol (E₂ ) facilitates receptive behaviour in E₂ benzoate (EB)-primed, ovariectomised female rats when it is administered i.c.v. or systemically. The present study tested the hypothesis that inhibitors of protein kinase A (PKA), protein kinase G (PKG) or the Src/mitogen-activated protein kinase (MAPK) complex interfere with E₂ facilitation of receptive behaviour. In Experiment 1, lordosis induced by i.c.v. infusion of E₂ was significantly reduced by i.c.v. administration of Rp-cAMPS, a PKA inhibitor, KT5823, a PKG inhibitor, and PP2 and PD98059, Src and MAPK inhibitors, respectively, between 30 and 240 minutes after infusion. In Experiment 2, we determined whether the ventromedial hypothalamus (VMH) is one of the neural sites at which those intracellular pathways participate in lordosis behaviour induced by E₂ . Administration of each of the four protein kinase inhibitors into the VMH blocked facilitation of lordosis induced by infusion of E₂ also into the VMH. These data support the hypothesis that activation of several protein kinase pathways is involved in the facilitation of lordosis by E₂ in EB-primed rats.

Mechanism of Rapid Nuclear Factor-E2-Related Factor 2 (Nrf2) Activation via Membrane-Associated Estrogen Receptors: Roles of NADPH Oxidase 1, Neutral Sphingomyelinase 2 and Epidermal Growth Factor Receptor (EGFR)

Membrane-associated estrogen receptors (ER)-α36 and G protein-coupled estrogen receptor (GPER) play important roles in the estrogen’s rapid non-genomic actions including stimulation of cell proliferation. Estrogen via these receptors induces rapid activation of transcription factor nuclear factor-E2-related factor 2 (Nrf2), a master regulator of detoxification and antioxidant systems, playing a key role in the metabolic reprogramming to support cell proliferation. This review highlights the possible mechanism underlying rapid Nrf2 activation via membrane-associated estrogen receptors by estrogen and phytoestrogens. Stimulation of ER-α36-GPER signaling complex rapidly induces Src-mediated transactivation of epidermal growth factor receptor (EGFR) leading to a kinase-mediated signaling cascade. We propose a novel hypothesis that ER-α36-GPER signaling initially induces rapid and temporal activation of NADPH oxidase 1 to generate superoxide, which subsequently activates redox-sensitive neutral sphingomyelinase 2 generating the lipid signaling mediator ceramide. Generation of ceramide is required for Ras activation and ceramide-protein kinase C ζ-casein kinase 2 (CK2) signaling. Notably, CK2 enhances chaperone activity of the Cdc37-Hsp90 complex supporting activation of various signaling kinases including Src, Raf and Akt (protein kinase B). Activation of Nrf2 may be induced by cooperation of two signaling pathways, (i) Nrf2 stabilization by direct phosphorylation by CK2 and (ii) EGFR-Ras-PI 3 kinase (PI3K)-Akt axis which inhibits glycogen synthase kinase 3β leading to enhanced nuclear transport and stability of Nrf2.

Prohibitin: A hypothetical target for sex-based new therapeutics for metabolic and immune diseases

IMPACT STATEMENT

Traditional sex-related biases in research are now obsolete, and it is important to identify the sex of humans, animals, and even cells in research protocols, due to the role of sex as a fundamental facet of biology, predisposition to disease, and response to therapy. Genetic sex, epigenetics and hormonal regulations, generate sex-dimorphisms. Recent investigations acknowledge sex differences in metabolic and immune health as well as chronic diseases. Prohibitin, an evolutionarily conserved molecule, has pleotropic functions in mitochondrial housekeeping, plasma membrane signaling, and nuclear genetic transcription. Studies in adipocytes, macrophages, and transgenic mice indicate that prohibitin interacts with sex steroids and plays a role in mediating sex differences in adipose tissues and immune cell types. Prohibitin may, depending on context, modulate predisposition to chronic metabolic diseases and malignancy and, because of these attributes, could be a target for sex-based therapies of metabolic and immune-related diseases as well as cancer.