Measurement of a Comprehensive Sex Steroid Profile in Rodent Serum by High-Sensitive Gas Chromatography-Tandem Mass Spectrometry

Estradiol protects against pain-facilitated fentanyl use via suppression of opioid-evoked dopamine activity in males

Pain relief is the most frequently reported motivation for opioid misuse, but it remains unclear how pain alters reward pathway function contributing to maladaptive opioid use and whether these neuroadaptations occur in a sex-specific manner. Here, we show that persistent inflammatory pain leads to augmented fentanyl self-administration in male, not female, rats. Wireless in vivo fiber photometry recordings and chemogenetic manipulations indicate that pain-facilitated fentanyl use is mediated by enhanced ventral tegmental area dopamine (VTADA) neuron responses during self-administration. In females, ovariectomy enhances fentanyl self-administration, but the protective effects of ovarian hormones are not solely mediated by estradiol per se. Instead, pain and high estradiol states-naturally occurring in intact females or artificially produced in males-suppress fentanyl self-administration and associated VTADA activity through VTA estrogen receptor beta signaling. These findings highlight the importance of assessing hormonal factors in opioid misuse liability in the context of pain.

The estrous cycle modulates hippocampal spine dynamics, dendritic processing, and spatial coding

Histological evidence suggests that the estrous cycle exerts a powerful influence on CA1 neurons in the mammalian hippocampus. Decades have passed since this landmark observation, yet how the estrous cycle shapes dendritic spine dynamics and hippocampal spatial coding in vivo remains a mystery. Here, we used a custom hippocampal microperiscope and two-photon calcium imaging to track CA1 pyramidal neurons in female mice across multiple cycles. Estrous cycle stage had a potent effect on spine dynamics, with spine density peaking during proestrus when estradiol levels are highest. These morphological changes coincided with greater somatodendritic coupling and increased infiltration of back-propagating action potentials into the apical dendrite. Finally, tracking CA1 response properties during navigation revealed greater place field stability during proestrus, evident at both the single-cell and population levels. These findings demonstrate that the estrous cycle drives large-scale structural and functional plasticity in hippocampal neurons essential for learning and memory.

A blocking antibody against anti-Müllerian hormone restores ovulation and normal androgen levels in a spontaneous rat model of polycystic ovary syndrome

BACKGROUND

Polycystic Ovary Syndrome (PCOS), the leading cause of infertility worldwide, is characterised by oligo-anovulation, hyperandrogenism, polycystic ovarian morphology and high Anti-Müllerian hormone (AMH) levels, associated with severe metabolic disturbances. However, the role of AMH in the physiopathology of this syndrome remains poorly understood and strategies to block its effects have never been investigated in animal models of PCOS.

METHODS

We used Western-blotting, ELISA and gene reporter approaches to evaluate the blocking efficacy, interspecificity and mechanism of action of an antibody against human AMH, Mab22A2. Then, we investigated the ability of a rat version of Mab22A2, rMab22A2, to alleviate reproductive dysfunction in Goto-Kakizaki (GK) rats, which spontaneously exhibit all the features of women with PCOS.

FINDINGS

We showed that Mab22A2 was interspecific, did not prevent AMH from binding to its receptor and was able to block the effects of AMH in gonadal cell lines. In addition, treatment of anovulatory GK rats with rMab22A2 reduced their bioavailable serum AMH levels and normalised their androgen concentrations. Finally, this treatment also induced ovulation in 84% of the rats and resulted in 66% of pregnancies.

INTERPRETATION

Our results show that AMH is a major driver of reproductive and hormonal dysfunction in PCOS and provide proof of concept that a blocking antibody against AMH can reverse the major reproductive dysfunction observed in PCOS, opening up promising avenues for the treatment of patients with PCOS.

FUNDING

Inserm, Sorbonne University, Inserm Transfert, the French Endocrine Society and the Medical Research Foundation (grant agreement n°EQU201903007868).

Acid-Sensing Ion Channel 1a Deficiency Drives Endocrine Hypertension in Male Mice

Background

Acid-sensing ion channel 1a (ASIC1a) is an H + -gated cation channel that responds to extracellular acidosis in both normal and pathological states, including ischemia, inflammation, and metabolic disturbances. While ASIC1a regulates vascular reactivity, its role in blood pressure regulation remains unclear, particularly concerning sex, aging, and disease. This study aims to investigate whether ASIC1a: 1) contributes to cardiovascular function in a sex-dependent manner; 2) plays a dynamic role in cardiovascular homeostasis with aging; and 3) modulates the development of angiotensin II-induced systemic hypertension.

Methods

Radiotelemeters were implanted in 6- and 18-month-old male and female wild-type ( Asic1a +/+ ) and ASIC1a knockout ( Asic1a -/- ) mice to monitor mean arterial blood pressure and heart rate under baseline conditions and in response to angiotensin II. Blood gases, electrolytes, hormones, and end-organ injury were also assessed.

Results

Aged male Asic1a -/- mice develop hypertension driven by aldosterone excess and sympathetic overactivity, which is accompanied by cardiac hypertrophy, aortic fibrosis, and glomerular hypertrophy. Female Asic1a -/- mice remain unaffected. In male Asic1a -/- mice, hyperaldosteronism occurs independent of the renin-angiotensin system and mitigates angiotensin II-induced hypertension. Furthermore, 6-month-old male Asic1a -/- mice exhibit elevated corticosterone, hypokalemia, reduced urine osmolality, increased pulse pressure, and cardiomyocyte hypertrophy that precedes hypertension.

Conclusions

These findings establish ASIC1a as a novel, sex-specific regulator of cardiovascular function, linking early corticosterone excess in male mice to hyperaldosteronism and implicating ASIC1a deficiency as a potential driver of endocrine-related hypertension.

GRAPHICAL ABSTRACT

Leveraging research into sex differences and steroid hormones to improve brain health

Sex differences, driven in part by steroid hormones, shape the structure and function of the brain throughout the lifespan and manifest across brain health and disease. The influence of steroid hormones on neuroplasticity, particularly in the adult hippocampus, differs between the sexes, which has important implications for disorders and diseases that compromise hippocampus integrity, such as depression and Alzheimer disease. This Review outlines the intricate relationship between steroid hormones and hippocampal neuroplasticity across the adult lifespan and explores how the unique physiology of male and female individuals can affect health and disease. Despite calls to include sex and gender in research, only 5% of neuroscience studies published in 2019 directly investigated the influence of sex. Drawing on insights from depression, Alzheimer disease and relevant hippocampal plasticity, this Review underscores the importance of considering sex and steroid hormones to achieve a comprehensive understanding of disease susceptibility and mechanisms. Such consideration will enable the discovery of personalized treatments, ultimately leading to improved health outcomes for all.

Associations between female sex hormones, estrous cycle, ischemic preconditioning and myocardial infarct size after ischemia-reperfusion injury

Studies on sex differences in myocardial infarction (MI) typically focus on males versus females, the exploration of hormonal physiologic variations and their impact on the infarct size remains limited. The objective of this study was to examine whether infarct size after myocardial ischemia/reperfusion injury in female rats differs in different phases of the estrous cycle, and according to the levels of sex hormones; and to assess whether the effect of ischemic preconditioning on infarct size varies in different phases of the estrous cycle and between sexes. Female rats were divided into three groups based on the estrous cycle: proestrus, estrus, and diestrus. A fourth group consisted of ovariectomized female rats. Male rats were included as a fifth group, and orchiectomized males as a sixth group. Each group underwent ischemia/reperfusion injury, with or without prior ischemic preconditioning (IPC). Plasma sex hormone levels were measured with gas chromatography-tandem mass spectrometry. Females in the proestrus showed significantly smaller infarct size compared to all other groups. Multivariable analyses identified proestrus, IPC, and estradiol as independent predictors of smaller infarct size while male sex and gonadectomy as independent predictors of larger infarct size. There was a statistical interaction between IPC and both sex and hormonal status, with a greater protective effect of IPC on infarct size in males and gonadectomized rats. After ischemia-reperfusion, proestrus female rats developed the smallest while male and gonadectomized rats the largest infarct size. Conversely, IPC conferred greater cardioprotection in male and gonadectomized rats than females in proestrus.

Unexpected mechanisms of sex-specific memory vulnerabilities to acute traumatic stress

It is increasingly recognized that severe acute traumatic events (e.g., mass shooting, natural disasters) can provoke enduring memory disturbances, and these problems are more common in women. We probed the fundamental sex differences underlying memory vulnerability to acute traumatic stress (ATS), focusing on the role of the sex hormone, estrogen (17β-estradiol) and its receptor signaling in hippocampus. Surprisingly, high physiological hippocampal estrogen levels were required for ATS-induced episodic memory disruption and the concurrent sensitization and generalization of fear memories in both male and female mice. Pharmacological and transgenic approaches demonstrated signaling via estrogen receptor (ER)α in males and, in contrast, ERβ in females, as the mechanisms for these memory problems. Finally, identify distinct hippocampal chromatin states governed by sex and estrogen levels, which may confer an enduring vulnerability to post-traumatic memory disturbances in females.

Single-cell profiling of the human endometrium in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) has a negative effect on the receptivity of the endometrium to embryo implantation and increases the risk of miscarriage and endometrial cancer. The cellular and molecular heterogeneity of the endometrium in women with PCOS has not been well studied. Our study presents a comprehensive cellular atlas of the endometrium during the proliferative phase in women with PCOS characterized by overweight and obesity, hyperandrogenism and insulin resistance compared with controls of similar age, weight and body mass index. Analysis of 247,791 isolated endometrial nuclei from 27 biopsies (5 controls and 12 PCOS cases at baseline and 7 after 16 weeks of metformin and 3 after lifestyle intervention) revealed cell-type-specific disease signatures and variations in cellular composition and localization. Samples taken after 16 weeks of metformin treatment and lifestyle management showed extensive recovery of disease-specific endometrial signatures. We linked the specific role of each cell type to clinical features such as hyperandrogenism and insulin resistance, and specific cell types to risk of endometrial and metabolic disease. In addition, potential therapeutic targets such as integrin inhibitors were identified and the role of metformin in restoring endometrial health in patients with PCOS was highlighted. Our findings lay the groundwork to significantly advance the understanding of PCOS-specific endometrial dysfunction for future targeted therapies.

Epidermal growth factor receptor contributes to indirect regulation of skeletal muscle mass by androgen

Androgen is widely acknowledged to regulate skeletal muscle mass. However, the specific mechanism driving muscle atrophy resulting from androgen deficiency remains elusive. Systemic androgen receptor knockout (ARKO) mice exhibit reduction in both muscle strength and muscle mass while skeletal muscle fiber specific ARKO mice have decreased muscle strength without affecting skeletal muscle mass in the limbs. Therefore, androgens may indirectly regulate skeletal muscle mass through effects on non-myofibers. Considering this, our investigation focused on blood fluid factors that might play a role in the regulation of skeletal muscle mass under the influence of androgens. Using a male mouse model of sham, orchidectomy and DHT replacement, mass spectrometry for serum samples of each group identified epidermal growth factor receptor (EGFR) as a candidate protein involving the regulation of skeletal muscle mass affected by androgens. Egfr expression in both liver and epididymal white adipose tissue correlated with androgen levels. Furthermore, Egfr expression in these tissues was predominantly elevated in male compared to female mice. Interestingly, male mice exhibited significantly elevated serum EGFR concentrations compared to their female counterparts, suggesting a connection with androgen levels. Treatment of EGFR to C2C12 cells promoted phosphorylation of AKT and its downstream S6K, and enhanced the protein synthesis in vitro. Furthermore, the administration of EGFR to female mice revealed a potential role in promoting an increase in skeletal muscle mass. These findings collectively enhance our understanding of the complex interplay among androgens, EGFR, and the regulation of skeletal muscle mass.

Sex and Region-Specific Differences in Microglial Morphology and Function Across Development

Microglia are exceptionally dynamic resident innate immune cells within the central nervous system, existing on a continuum of morphologies and functions throughout their lifespan. They play vital roles in response to injuries and infections, clearing cellular debris, and maintaining neural homeostasis throughout development. Emerging research suggests that microglia are strongly influenced by biological factors, including sex, developmental stage, and their local environment. This review synthesizes findings on sex differences in microglial morphology and function in key brain regions, including the frontal cortex, hippocampus, amygdala, hypothalamus, basal ganglia, and cerebellum, across the lifespan. Where available, we examine how gonadal hormones influence these microglial characteristics. Additionally, we highlight the limitations of relying solely on morphology to infer function and underscore the need for comprehensive, multimodal approaches to guide future research. Ultimately, this review aims to advance the dialogue on these spatiotemporally heterogeneous cells and their implications for sex differences in brain function and vulnerability to neurological and psychiatric disorders.

Gonad-derived steroid hormones mediate a sex difference in the maturation of auditory encoding in the cochlea from adolescence to early adulthood in C57BL/6J mice

Sexually mature females of multiple mammalian species were previously reported to have increased peripheral auditory sensitivity, often measured as higher auditory brainstem response (ABR) wave I amplitude compared to males. Here, we determined potential hormonal and genetic (i.e., XX- vs. XY-linked genes) contributions to this sex difference by recording ABRs in gonadally intact and gonadectomized female and male wildtype (WT) and four core genotypes (FCG) C57BL/6J mice. WT females at postnatal day 38 (P38) and P65, and FCG mice with ovaries at P65 had higher wave I amplitude than males, and the difference was absent in gonadectomized mice. Furthermore, in WT mice, we addressed the initiation and duration of the sex difference in wave amplitude from pre-pubescence (P25) through maturation from post-pubescent late adolescence to early adulthood (P38, P65, and P95) in both the cochlea and cochlear nucleus. In both female and male mice, wave I amplitude decreased by 50 % from P25 to P95. However, the amplitude in females was 22 % and 11 % higher than males at P38 and P65, respectively. In gonadectomized mice, there was no sex difference in wave I amplitude at any age tested, due to a decrease in gonadectomized females. In contrast, we found that wave II amplitude remains relatively constant over these ages in both sham and gonadectomized WT female and male mice. Together, the data suggest that gonad-derived hormones differentially refine the maturation of wave I, but not wave II, amplitude between late adolescence and early adulthood.

Impact of the estrous cycle on brain monoamines and behavioral and respiratory responses to CO2 in mice

The prevalence of panic disorder is two to four times higher in women compared to that in men, and hormonal changes during the menstrual cycle play a role in the occurrence of panic attacks. Here, we investigated the effect of the estrous cycle on the ventilatory and behavioral responses to CO2 in mice. Female mice in proestrus, estrus, metestrus, or diestrus were exposed to 20% CO2, and their escape behaviors, brain monoamines, and plasma levels of 17β-estradiol (E2) and progesterone (P4) were measured. Pulmonary ventilation (V̇E), oxygen consumption (V̇O2), and body core temperature (TB) were also measured during normocapnia followed by CO2. Females exposed to 20% CO2 exhibited an escape behavior, but the estrous cycle did not affect this response. Females in all phases of the estrous cycle showed higher V̇E and lower TB during hypercapnia. In diestrus, there was an attenuation of CO2-induced hyperventilation with no change in V̇O2, whereas in estrus, this response was accompanied by a reduction in V̇O2. Hypercapnia also increased the concentration of plasma P4 and central DOPAC, the main dopamine metabolite, in all females. There was an estrous cycle effect on brainstem serotonin, with females in estrus showing a higher concentration than females in the metestrus and diestrus phases. Therefore, our data suggest that hypercapnia induces panic-related behaviors and ventilatory changes that lead to an increase in P4 secretion in female mice, likely originating from the adrenals. The estrous cycle does not affect the behavioral response but interferes in the ventilatory and metabolic responses to CO2 in mice.

Mimicking women's endocrine milieu in mice for women's health-related studies

To improve preclinical studies and their translation, patient-derived xenografts (PDXs) are increasingly used. They have human-specific tumor characteristics and reflect intra and inter-tumor heterogeneity. However, the endocrine milieu differs between humans and host mice. In light of sex-specific cancer biology and a rise in endocrine-related cancers there is an urgent need to correctly reflect the hormonal milieu in PDX models. We show that female mice of NOD.Cg-Prkdc scid Il2rg tm1Wjl /SzJ (NSG) strain widely used for PDXs has 17-β-estradiol (E2) and testosterone (T) levels comparable to C57Bl6 females but higher progesterone (P4) levels. E2 levels are comparable, T levels are lower and P4 levels higher than those observed in postmenopausal women. Ovariectomy increases T to levels observed in postmenopausal women. Subcutaneous E2 and combined E2/P4 silicon pellets provide NSG females with premenopausal ovarian hormone levels. These procedures humanize the endocrine environment of experimental animals, improving PDX relevance in women's health-related research.

Estrogen-Regulated Lateral Septal Kisspeptin Neurons Abundantly Project to GnRH Neurons and the Hypothalamic Supramammillary Nucleus

While hypothalamic kisspeptin (KP) neurons play well-established roles in the estrogen-dependent regulation of reproduction, little is known about extrahypothalamic KP-producing (KPLS) neurons of the lateral septum. As established previously, Kiss1 expression in this region is low and regulated by estrogen receptor- and GABAB receptor-dependent mechanisms. Our present experiments on Kiss1-Cre/ZsGreen knock-in mice revealed that transgene expression in the LS begins at Postnatal Day (P)33-36 in females and P40-45 in males and is stimulated by estrogen receptor signaling. Fluorescent cell numbers continue to increase in adulthood and are higher in females. Viral tracing uncovered that the bulk of KPLS fibers joins the medial forebrain bundle and terminates in the hypothalamic supramammillary nucleus. Smaller subsets innervate the medial amygdala or project to other limbic structures. One-quarter of gonadotropin-releasing hormone (GnRH)-immunoreactive perikarya in the preoptic area and their dendrites receive appositions from KPLS axons. OVX adult Kiss1-Cre/ZsGreen mice treated for 4 d with 17β-estradiol or vehicle were used for RNA sequencing studies of laser-microdissected KPLS neurons. The transcriptome included markers of GABAergic and neuropeptidergic (Penk, Cartpt, Vgf) cotransmission and 571 estrogen-regulated transcripts. Estrogen treatment upregulated the acetylcholine receptor transcript Chrm2 and, in slice electrophysiology experiments, caused enhanced muscarinic inhibition of KPLS neurons. Finally, we provided immunohistochemical evidence for homologous neurons in the postmortem human brain, suggesting that KPLS neurons may contribute to evolutionarily conserved regulatory mechanisms. Future studies will need to investigate the putative roles of KPLS neurons in the estrogen-dependent control of GnRH neurons and/or various hypothalamic/limbic functions.

Sex Chromosomes and Sex Hormones: Dissecting the Forces That Differentiate Female and Male Hearts

The heart is a highly sex-biased organ, as sex shapes innumerable aspects of heart health and disease. Sex chromosomes and sex hormones -testosterone, progesterone, and estrogen- establish and perpetuate the division between male and female myocardium. Of these differentiating factors, the insulating effects of estrogen have been rigorously interrogated and reviewed, whereas the influence of sex chromosomes, testosterone, and progesterone remains in dispute or ill-defined. Here, we synthesize growing evidence that sex chromosomes and sex hormones substantially bias heart form, function, and dysfunction in a context-dependent fashion. The discrete protective functions ascribed to each of the 3 estrogen receptors are also enumerated. Subsequently, we overview obstacles that have historically discouraged the inclusion of female subjects in basic science such as the impact of the female estrus cycle and reproductive senescence on data reliability and reproducibility. Furthermore, we weigh the utility of several common strategies to intercept and rescue sex-specific protection. Last, we warn of common compounds in animal chow and cell culture that interfere with estrogen signaling. In sum, we survey the controversies and challenges that stem from sex-inclusive cardiovascular research, comparing the possible causes of cardiac sex bias, elucidating sex chromosome or hormone-dependent processes in the heart, describing common lapses that imperil female and male cell and animal work, and illuminating facets of the female heart yet unexplored or still uncertain.

Brain aromatase and its relationship with parental experience and behavior in male mice

Introduction

In most mammals, paternal care is not mandatory for raising offspring. In house mice, experience with pups governs the extent and quality of paternal care. First-time fathers undergo a dramatic transition from ignoring or killing pups to caring for pups. The behavioral shift occurs together with changes in brain estrogen signaling as indicated by changes in estrogen receptor presence and distribution in multiple areas regulating olfaction, emotion, and motivation.

Methods

We measured changes in the expression of aromatase, the enzyme converting testosterone into estrogen, as an indirect measure of estrogen synthesis, in various areas of the limbic system in mice with increasing paternal experience.

Results

The amount of paternal experience (5 or 27 days) was associated with increased numbers of immunocytochemically-identified aromatase expressing cells in the medial and cortical amygdala, posterior piriform cortex, and ventromedial hypothalamus. Functionally, these changes can be related to the disappearance of aggression or neglect towards pups when first-time fathers or, even more, well-experienced fathers are handling their own pups. In the lateral septum, the anterior piriform cortex and to some extent in the medial preoptic area, parental experience increased the number of aromatase-positive cells only in fathers with 27 days of experience, and only in the right hemisphere. This represents a novel case of brain-functional lateralization triggered by experience. Nuclei/areas associated with maternal care (medial preoptic area, bed nucleus of stria terminalis, nucleus accumbens) exhibited a left-hemisphere advantage in aromatase expressing cells, both in pup-naïve and pup-experienced males. This newly found lateralization may contribute to the left-hemisphere dominant processing and perception of pup calls to release parental behavior.

Conclusion

In general, the experience-dependent changes in aromatase expression we observed in most brain areas did not mirror the previously reported changes in estrogen receptors (ERα) when pup-naïve males became pup-caring fathers. Hence, paternal behavior may depend, in a brain area-specific way, on the differential action of estrogen through its receptors and/or direct local modulation of neural processing.

Testosterone exacerbates neutrophilia and cardiac injury in myocardial infarction via actions in bone marrow

Men develop larger infarct sizes than women after a myocardial infarction (MI), but the mechanism underlying this sex difference is unknown. Here, we demonstrated that blood neutrophil counts post-MI were higher in male than female mice. Castration-induced testosterone deficiency reduced blood neutrophil counts to the level in females and increased survival post-MI. These effects were mimicked by Osterix-directed ablation of the androgen receptor in bone marrow (BM). Mechanistically, androgens downregulated the leukocyte retention factor CXCL12 in BM stromal cells. Post-hoc analysis of clinical trial data showed that neutrophilia was greater in men than women after reperfusion of first-time ST-elevation MI, and tocilizumab, an interleukin-6 receptor inhibitor, reduced blood neutrophil counts and infarct size to a greater extent in men than women. Our work reveals a previously unknown mechanism connecting testosterone with neutrophilia and MI injury via BM and identifies the importance of considering sex when developing anti-inflammatory strategies to treat MI.

Guidelines for sex-specific considerations to improve rigor in renal research and how we got there

Biological sex significantly influences disease presentation, progression, and therapeutic outcomes in chronic kidney disease and acute kidney injury. Sex hormones, including estrogen and testosterone, modulate key renal functions, including renal blood flow, glomerular filtration, and electrolyte transport, thereby affecting disease trajectory in a sex-specific manner. It is critical for researchers to understand why and how to integrate sex as a biological variable in data collection, analysis, and reporting. Integrating a sex-based perspective in kidney research will lead to more personalized and efficacious treatment strategies, optimizing therapeutic interventions for each sex. If addressed properly, the incorporation of sex as a biological variable (SABV) in renal research not only enhances the mechanistic understanding of renal disease, but also paves the way for precision medicine, promising improved clinical outcomes, and tailored treatment protocols for all patients. This paper is designed to serve as a guideline for researchers interested in rigorously incorporating sex as a biological variable in their studies.

ERα dysfunction caused by ESR1 mutations and therapeutic pressure promotes lineage plasticity in ER+ breast cancer

Multiple next-generation molecules targeting estrogen receptor α (ERα) are being investigated in breast cancer clinical trials, encompassing thousands of women globally. Development of these molecules was partly motivated by the discovery of resistance-associated mutations in ESR1 (encodes ERα). Here, we studied the impact of ERα antagonist/degraders against Esr1 mutations expressed in mouse mammary glands. Inhibition of mutant ERα induced mixed-lineage cells, characterized by aberrant co-engagement of normally disparate master transcription factors. Lineage infidelity was also observed in Esr1-wild-type mice upon long-term estrogen deprivation. In ER+ breast cancer biopsy specimens, heavily pretreated tumors with no ESR1 mutation detected (NMD) frequently exhibited mixed-lineage features. ESR1-mutant tumors generally retained luminal features and higher ERα activity and exhibited an anti-proliferative response to the ERα antagonist giredestrant. ESR1-mutant tumors acquired mixed-lineage features following treatment. Lineage heterogeneity in advanced ER+ breast cancer may underpin the differential benefit of investigational ERα therapeutics observed in ESR1-mutant versus NMD contexts.

The Hypothalamus and Pituitary Gland Regulate Reproduction and Are Involved in the Development of Polycystic Ovary Syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is a complex condition with unclear mechanisms, posing a challenge for prevention and treatment of PCOS. The role of the hypothalamus and pituitary gland in regulating female reproduction is critical. Abnormalities in the hypothalamus and pituitary can impair reproductive function. It is important to study hypothalamic and pituitary changes in patients with PCOS.

SUMMARY

This article reviews articles on the hypothalamus and PCOS with the goal of summarizing what abnormalities of the hypothalamic-pituitary-ovarian axis are present in patients with PCOS and to clarify the pathogenesis of PCOS. We find that the mechanisms by which the hypothalamus and pituitary regulate reproduction in girls are complex and are associated with altered sex hormone levels, obesity, and insulin resistance. Different animal models of PCOS are characterized by different alterations in the hypothalamus and pituitary and respond differently to different treatments, which correspond to the complex pathogenesis of patients with PCOS.

KEY MESSAGES

Arcuate nucleus (ARC) is associated with luteinizing hormone (LH) surges. Suprachiasmatic nucleus, ARC, and RP3V are associated with LH surges. Animal models of PCOS have different characteristics.

The androgen clock is an epigenetic predictor of long-term male hormone exposure

Aging is a complex process characterized by biological decline and a wide range of molecular alterations to cells, including changes to DNA methylation. In this study, we used a male-specific epigenetic marker of aging to build an epigenetic predictor that measures long-term androgen exposure in sheep and mice (median absolute error of 4.3 and 1.4 mo, respectively). We term this predictor the androgen clock and show its "tick" is mediated by the androgen receptor and can be accelerated beyond that in normal male mice by supplementing females with dihydrotestosterone. Conversely, the removal of androgens by castration in sheep completely halted the androgen clock. In addition to potential applications in medicine and agriculture, we predict the androgen clock will prove a useful model to understand the mechanisms and processes of age-associated DNA methylation change because it can be precisely enhanced and halted using small molecule manipulation with few additional effects on the cell.

Menopause-induced 17β-estradiol and progesterone loss increases senescence markers, matrix disassembly and degeneration in mouse cartilage

Female individuals who are post-menopausal present with higher incidence of knee osteoarthritis (KOA) than male counterparts; however, the mechanisms underlying this disparity are unknown. The most commonly used preclinical models lack human-relevant menopausal phenotypes, which may contribute to our incomplete understanding of sex-specific differences in KOA pathogenesis. Here we chemically induced menopause in middle-aged (14-16 months) C57/BL6N female mice. When we mapped the trajectory of KOA over time, we found that menopause aggravated cartilage degeneration relative to non-menopause controls. Network medicine analyses revealed that loss of 17β-estradiol and progesterone with menopause enhanced susceptibility to senescence and extracellular matrix disassembly. In vivo, restoration of 17β-estradiol and progesterone in menopausal mice protected against cartilage degeneration compared to untreated menopausal controls. Accordingly, post-menopausal human chondrocytes displayed decreased markers of senescence and increased markers of chondrogenicity when cultured with 17β-estradiol and progesterone. These findings implicate menopause-associated senescence and extracellular matrix disassembly in the sex-specific pathogenesis of KOA.

Cellular and molecular mechanisms of action of ovarian steroid hormones II: Regulation of sexual behavior in female rodents

Female sexual behaviors in rodents (lordosis and appetitive or "proceptive" behaviors) are induced through a genomic mechanism by the sequential actions of estradiol (E2) and progesterone (P), or E2 and testosterone (T) at their respective receptors. However, non-steroidal agents, such as gonadotropin-releasing hormone (GnRH), Prostaglandin E2 (PGE2), noradrenaline, dopamine, oxytocin, α-melanocyte stimulating hormone, nitric oxide, leptin, apelin, and others, facilitate different aspects of female sexual behavior through their cellular and intracellular effects at the membrane and genomic levels in ovariectomized rats primed with E2. These neurotransmitters often act as intermediaries of E2 and P (or T). The classical model of steroid hormone action through intracellular receptor binding has been complemented by an alternative scenario wherein the steroid functions as a transcription factor after binding the receptor protein to DNA. Another possible mechanism occurs through the activation of second messenger systems (cyclic AMP, cyclic GMP, calcium), which subsequently initiate phosphorylation events via diverse kinase systems (protein kinases A, G, or C). These kinases target the progesterone receptor (PR) or associated effector proteins that connect the PR to the trans-activation machinery. This may also happen to the androgen receptor (AR). In addition, other cellular mechanisms could be involved since the chemical structure of these non-steroidal agents causes a change in their lipophobicity that prevents them from penetrating the cell and exerting direct transcriptional effects; however, they can exert effects on different components of the cell membrane activating a cross-talk between the cell membrane and the regulation of the transcriptional mechanisms.

A glucocorticoid spike derails muscle repair to heterotopic ossification after spinal cord injury

Why severe injury to the central nervous system (CNS) triggers the development of large neurogenic heterotopic ossifications (NHOs) within periarticular muscles remains unknown. We report that spinal cord injury (SCI) triggers a rapid corticosterone spike in mice, which is causal for NHO development because treatments with corticosterone or the synthetic glucocorticoid (GC) receptor (GR) agonist dexamethasone are sufficient to trigger heterotopic ossification and upregulate the expression of osteoinductive and osteogenic differentiation genes in injured muscles even without SCI. The central role for GR signaling in causing NHO is further demonstrated in mice deleted for the GR gene (Nr3c1), which no longer develop NHO after SCI. Furthermore, administration of clinical GR antagonists inhibits NHO development in mice with SCI. This study identifies endogenous GC as causing pathological NHO after CNS injury and suggests that GR antagonists may be of prophylactic use to prevent NHO development in victims of severe CNS injuries.

Is FAM19A5 an adipokine? Peripheral FAM19A5 in wild-type, FAM19A5 knockout, and LacZ knockin mice

FAM19A5 is a novel secretory protein expressed primarily in the brain. However, a recent study reported that FAM19A5 is an adipocyte-derived adipokine that regulates vascular smooth muscle function through sphingosine-1-phosphate receptor 2 (S1PR2). In our study, we investigated FAM19A5 transcript and protein levels in peripheral tissues, including adipose tissues, from wild-type, FAM19A5 knockout, and FAM19A5-LacZ knockin mice. We found that the FAM19A5 transcript levels in the central nervous system were much greater than those in any of the peripheral tissues, including adipose tissues. Furthermore, the FAM19A5 protein levels in adipose and reproductive tissues were below detectable limits for Western blot analysis and enzyme-linked immunosorbent assay (ELISA). Additionally, we found that the FAM19A5 protein did not interact with S1PR2 in terms of G-protein-mediated signal transduction, β-arrestin recruitment, or ligand-mediated internalization. Taken together, our findings revealed basal levels of FAM19A5 transcripts and proteins in peripheral tissues, confirming its primary expression in the central nervous system and lack of significant interaction with S1PR2.

Sexual dimorphism of MASLD-driven bone loss

Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) is highly prevalent with major risk of progression to Metabolic Dysfunction-Associated Steatohepatitis (MASH) and Hepatocellular Carcinoma (HCC). Recently, osteoporosis and bone fracture have emerged as sexually-dimorphic comorbidities of MASLD yet the mechanisms of this bone loss are unknown. Herein, we address these knowledge gaps using DIAMOND mice which develop MASLD, MASH, and HCC via Western diet exposure. We examined the skeletal phenotype of male DIAMOND mice after 16, 36, and 48 weeks of exposure to Western or control diet. At 16 weeks, male DIAMOND mice with MASLD lose trabecular bone but retain mechanical bone integrity. At 48 weeks, males lose cortical bone and mechanical integrity, indicating severe skeletal weakening. Female DIAMOND mice were protected from cortical and trabecular MASLD-associated bone loss and skeletal fragility at all timepoints. Using NicheNet, a publicly available database of hepatic mRNA expression in DIAMOND mice, and a PTH-induced model of bone loss, we suggest Ctgf, Rarres2, Anxa2, Fgf21, and Mmp13 are liver-secreted ligands inducing bone resorption. This study is the first preclinical investigation of bone loss in MASLD, and the first to suggest the role of Ctgf, Rarrest2, Anxa2, Fgf21, and Mmp13 as drivers of this pathology.

Postnatal Dysregulation of Androgens in Extremely Preterm Male Infants

Context

Neurodevelopmental impairments are common among survivors of extremely preterm birth, particularly in males. Hyperactivation of the hypothalamic-pituitary-gonadal (HPG) axis has been suggested as an underlying cause, but this has been poorly investigated.

Objective

Establish levels and temporal changes in circulating androgens in extremely preterm infant males.

Methods

Observational cohort study analyzing cord blood serum (n = 25) and postnatal plasma (n = 13) collected from day 0 until week 11 from infant males born at 22.8-27.9 weeks gestational age. Testosterone and dihydrotestosterone (DHT) were determined using gas chromatography mass spectrometry, sex hormone-binding globulin (SHBG) with an enzyme-linked immunosorbent assay, and follicle-stimulating hormone (FSH) and luteinizing hormone (LH) with the Luminex xMAP multiplex assay.

Results

Testosterone and DHT levels were higher on day 0 (median 4.27 and 0.30 ng/mL) than in cord blood (0.15 and 0.01 ng/mL) (P < .001 for both). Levels of the hormones then declined rapidly until day 5 (median 0.16 and 0.12 ng/mL), then remained relatively constant throughout the study period. Median levels of testosterone and DHT across the whole study period were approximately 6-fold higher than reported in utero levels. FSH and LH showed similar postnatal patterns as the androgens. SHBG steadily increased over time, and, as a result, the fraction of bioavailable testosterone declined with infant postnatal age.

Conclusion

The HPG axis is activated immediately after birth in extremely preterm infant males, resulting in an androgen pulse occurring several months earlier than during a normal pregnancy. The long-term implications of high androgen exposure during a sensitive neurodevelopmental period warrant further studies.

Unexpected nuclear hormone receptor and chromatin dynamics regulate estrous cycle dependent gene expression

Chromatin changes in response to estrogen and progesterone are well established in cultured cells, but how they control gene expression under physiological conditions is largely unknown. To address this question, we examined in vivo estrous cycle dynamics of mouse uterus hormone receptor occupancy, chromatin accessibility and chromatin structure by combining RNA-seq, ATAC-seq, HiC-seq and ChIP-seq. Two estrous cycle stages were chosen for these analyses, diestrus (highest estrogen) and estrus (highest progesterone). Unexpectedly, rather than alternating with each other, estrogen receptor alpha (ERα) and progesterone receptor (PGR) were co-bound during diestrus and lost during estrus. Motif analysis of open chromatin followed by hypoxia inducible factor 2A (HIF2A) ChIP-seq and conditional uterine deletion of this transcription factor revealed a novel role for HIF2A in regulating diestrus gene expression patterns that were independent of either ERα or PGR binding. Proteins in complex with ERα included PGR and cohesin, only during diestrus. Combined with HiC-seq analyses, we demonstrate that complex chromatin architecture changes including enhancer switching are coordinated with ERα and PGR co-binding during diestrus and non-hormone receptor transcription factors such as HIF2A during estrus to regulate most differential gene expression across the estrous cycle.

The androgen receptor in mesenchymal progenitors regulates skeletal muscle mass via Igf1 expression in male mice

Androgens exert their effects primarily by binding to the androgen receptor (AR), a ligand-dependent nuclear receptor. While androgens have anabolic effects on skeletal muscle, previous studies reported that AR functions in myofibers to regulate skeletal muscle quality, rather than skeletal muscle mass. Therefore, the anabolic effects of androgens are exerted via nonmyofiber cells. In this context, the cellular and molecular mechanisms of AR in mesenchymal progenitors, which play a crucial role in maintaining skeletal muscle homeostasis, remain largely unknown. In this study, we demonstrated expression of AR in mesenchymal progenitors and found that targeted AR ablation in mesenchymal progenitors reduced limb muscle mass in mature adult, but not young or aged, male mice, although fatty infiltration of muscle was not affected. The absence of AR in mesenchymal progenitors led to remarkable perineal muscle hypotrophy, regardless of age, due to abnormal regulation of transcripts associated with cell death and extracellular matrix organization. Additionally, we revealed that AR in mesenchymal progenitors regulates the expression of insulin-like growth factor 1 (Igf1) and that IGF1 administration prevents perineal muscle atrophy in a paracrine manner. These findings indicate that the anabolic effects of androgens regulate skeletal muscle mass via, at least in part, AR signaling in mesenchymal progenitors.

The estrous cycle modulates hippocampal spine dynamics, dendritic processing, and spatial coding

Histological evidence suggests that the estrous cycle exerts a powerful effect on CA1 neurons in mammalian hippocampus. Decades have passed since this landmark observation, yet how the estrous cycle shapes dendritic spine dynamics and hippocampal spatial coding in vivo remains a mystery. Here, we used a custom hippocampal microperiscope and two-photon calcium imaging to track CA1 pyramidal neurons in female mice over multiple cycles. Estrous cycle stage had a potent effect on spine dynamics, with heightened density during periods of greater estradiol (proestrus). These morphological changes were accompanied by greater somatodendritic coupling and increased infiltration of back-propagating action potentials into the apical dendrite. Finally, tracking CA1 response properties during navigation revealed enhanced place field stability during proestrus, evident at the single-cell and population level. These results establish the estrous cycle as a driver of large-scale structural and functional plasticity in hippocampal circuits essential for learning and memory.

Transcriptomic Analysis of Pubertal and Adult Virgin Mouse Mammary Epithelial and Stromal Cell Populations

Conflicting data exist as to how mammary epithelial cell proliferation changes during the reproductive cycle. To study the effect of endogenous hormone fluctuations on gene expression in the mouse mammary gland, we performed bulk RNAseq analyses of epithelial and stromal cell populations that were isolated either during puberty or at different stages of the adult virgin estrous cycle. Our data confirm prior findings that proliferative changes do not occur in every mouse in every cycle. We also show that during the estrous cycle the main gene expression changes occur in adipocytes and fibroblasts. Finally, we present a comprehensive overview of the Wnt gene expression landscape in different mammary gland cell types in pubertal and adult mice. This work contributes to understanding the effects of physiological hormone fluctuations and locally produced signaling molecules on gene expression changes in the mammary gland during the reproductive cycle and should be a useful resource for future studies investigating gene expression patterns in different cell types across different developmental timepoints.

The physiological and biochemical basis of potency thresholds modeled using human estrogen receptor alpha: implications for identifying endocrine disruptors

The endocrine system functions by interactions between ligands and receptors. Ligands exhibit potency for binding to and interacting with receptors. Potency is the product of affinity and efficacy. Potency and physiological concentration determine the ability of a ligand to produce physiological effects. The kinetic behavior of ligand-receptor interactions conforms to the laws of mass action. The laws of mass action define the relationship between the affinity of a ligand and the fraction of cognate receptors that it occupies at any physiological concentration. We previously identified the minimum ligand potency required to produce clinically observable estrogenic agonist effects via the human estrogen receptor-alpha (ERα). By examining data on botanical estrogens and dietary supplements, we demonstrated that ERα ligands with potency lower than one one-thousandth that of the primary endogenous hormone 17β-estradiol (E2) do not produce clinically observable estrogenic effects. This allowed us to propose a Human-Relevant Potency Threshold (HRPT) for ERα ligands of 1 × 10-4 relative to E2. Here, we test the hypothesis that the HRPT for ERα arises from the receptor occupancy by the normal metabolic milieu of endogenous ERα ligands. The metabolic milieu comprises precursors to hormones, metabolites of hormones, and other normal products of metabolism. We have calculated fractional receptor occupancies for ERα ligands with potencies below and above the previously established HRPT when normal circulating levels of some endogenous ERα ligands and E2 were also present. Fractional receptor occupancy calculations showed that individual ERα ligands with potencies more than tenfold higher than the HRPT can compete for occupancy at ERα against individual components of the endogenous metabolic milieu and against mixtures of those components at concentrations found naturally in human blood. Ligands with potencies less than tenfold higher than the HRPT were unable to compete successfully for ERα. These results show that the HRPT for ERα agonism (10-4 relative to E2) proposed previously is quite conservative and should be considered strong evidence against the potential for disruption of the estrogenic pathway. For chemicals with potency 10-3 of E2, the potential for estrogenic endocrine disruption must be considered equivocal and subject to the presence of corroborative evidence. Most importantly, this work demonstrates that the endogenous metabolic milieu is responsible for the observed ERα agonist HRPT, that this HRPT applies also to ERα antagonists, and it provides a compelling mechanistic explanation for the HRPT that is grounded in basic principles of molecular kinetics using well characterized properties and concentrations of endogenous components of normal metabolism.

Sex- and cycle-dependent changes in spine density and size in hippocampal CA2 neurons

Sex hormones affect structural and functional plasticity in the rodent hippocampus. However, hormone levels not only differ between males and females, but also fluctuate across the female estrous cycle. While sex- and cycle-dependent differences in dendritic spine density and morphology have been found in the rodent CA1 region, but not in the CA3 or the dentate gyrus, comparable structural data on CA2, i.e. the hippocampal region involved in social recognition memory, is so far lacking. In this study, we, therefore, used wildtype male and female mice in diestrus or proestrus to analyze spines on dendritic segments from identified CA2 neurons. In basal stratum oriens, we found no differences in spine density, but a significant shift towards larger spine head areas in male mice compared to females. Conversely, in apical stratum radiatum diestrus females had a significantly higher spine density, and females in either cycle stage had a significant shift towards larger spine head areas as compared to males, with diestrus females showing the larger shift. Our results provide further evidence for the sexual dimorphism of hippocampal area CA2, and underscore the importance of considering not only the sex, but also the stage of the estrous cycle when interpreting morphological data.

Sex Matters-Insights from Testing Drug Efficacy in an Animal Model of Pancreatic Cancer

Preclinical studies rarely test the efficacy of therapies in both sexes. The field of oncology is no exception in this regard. In a model of syngeneic, orthotopic, metastasized pancreatic ductal adenocarcinoma we evaluated the impact of sex on pathological features of this disease as well as on the efficacy and possible adverse side effects of a novel, small molecule-based therapy inhibiting KRAS:SOS1, MEK1/2 and PI3K signaling in male and female C57BL/6J mice. Male mice had less tumor infiltration of CD8-positive cells, developed bigger tumors, had more lung metastasis and a lower probability of survival compared to female mice. These more severe pathological features in male animals were accompanied by higher distress at the end of the experiment. The evaluated inhibitors BI-3406, trametinib and BKM120 showed synergistic effects in vitro. This combinatorial therapy reduced tumor weight more efficiently in male animals, although the drug concentrations were similar in the tumors of both sexes. These results underline the importance of sex-specific preclinical research and at the same time provide a solid basis for future studies with the tested compounds.

Simultaneous Determination of Selected Steroids with Neuroactive Effects in Human Serum by Ultrahigh-Performance Liquid Chromatography-Tandem Mass Spectrometry

Neuroactive steroids are a group of steroid molecules that are involved in the regulation of functions of the nervous system. The nervous system is not only the site of their action, but their biosynthesis can also occur there. Neuroactive steroid levels depend not only on the physiological state of an individual (person's sex, age, diurnal variation, etc.), but they are also affected by various pathological processes in the nervous system (some neurological and psychiatric diseases or injuries), and new knowledge can be gained by monitoring these processes. The aim of our research was to develop and validate a comprehensive method for the simultaneous determination of selected steroids with neuroactive effects in human serum. The developed method enables high throughput and a sensitive quantitative analysis of nine neuroactive steroid substances (pregnenolone, progesterone, 5α-dihydroprogesterone, allopregnanolone, testosterone, 5α-dihydrotestosterone, androstenedione, dehydroepiandrosterone, and epiandrosterone) in 150 μL of human serum by ultrahigh-performance liquid chromatography with tandem mass spectrometry. The correlation coefficients above 0.999 indicated that the developed analytical procedure was linear in the range of 0.90 nmol/L to 28.46 μmol/L in human serum. The accuracy and precision of the method for all analytes ranged from 83 to 118% and from 0.9 to 14.1%, respectively. This described method could contribute to a deeper understanding of the pathophysiology of various diseases. Similarly, it can also be helpful in the search for new biomarkers and diagnostic options or therapeutic approaches.

HSD17B1 Compensates for HSD17B3 Deficiency in Fetal Mouse Testis but Not in Adults

Hydroxysteroid (17β) dehydrogenase (HSD17B) enzymes convert 17-ketosteroids to 17beta-hydroxysteroids, an essential step in testosterone biosynthesis. Human XY individuals with inactivating HSD17B3 mutations are born with female-appearing external genitalia due to testosterone deficiency. However, at puberty their testosterone production reactivates, indicating HSD17B3-independent testosterone synthesis. We have recently shown that Hsd17b3 knockout (3-KO) male mice display a similar endocrine imbalance, with high serum androstenedione and testosterone in adulthood, but milder undermasculinization than humans. Here, we studied whether HSD17B1 is responsible for the remaining HSD17B activity in the 3-KO male mice by generating a Ser134Ala point mutation that disrupted the enzymatic activity of HSD17B1 (1-KO) followed by breeding Hsd17b1/Hsd17b3 double-KO (DKO) mice. In contrast to 3-KO, inactivation of both HSD17B3 and HSD17B1 in mice results in a dramatic drop in testosterone synthesis during the fetal period. This resulted in a female-like anogenital distance at birth, and adult DKO males displayed more severe undermasculinization than 3-KO, including more strongly reduced weight of seminal vesicles, levator ani, epididymis, and testis. However, qualitatively normal spermatogenesis was detected in adult DKO males. Furthermore, similar to 3-KO mice, high serum testosterone was still detected in adult DKO mice, accompanied by upregulation of various steroidogenic enzymes. The data show that HSD17B1 compensates for HSD17B3 deficiency in fetal mouse testis but is not the enzyme responsible for testosterone synthesis in adult mice with inactivated HSD17B3. Therefore, other enzymes are able to convert androstenedione to testosterone in the adult mouse testis and presumably also in the human testis.

The cycling and aging mouse female reproductive tract at single-cell resolution

The female reproductive tract (FRT) undergoes extensive remodeling during reproductive cycling. This recurrent remodeling and how it shapes organ-specific aging remains poorly explored. Using single-cell and spatial transcriptomics, we systematically characterized morphological and gene expression changes occurring in ovary, oviduct, uterus, cervix, and vagina at each phase of the mouse estrous cycle, during decidualization, and into aging. These analyses reveal that fibroblasts play central-and highly organ-specific-roles in FRT remodeling by orchestrating extracellular matrix (ECM) reorganization and inflammation. Our results suggest a model wherein recurrent FRT remodeling over reproductive lifespan drives the gradual, age-related development of fibrosis and chronic inflammation. This hypothesis was directly tested using chemical ablation of cycling, which reduced fibrotic accumulation during aging. Our atlas provides extensive detail into how estrus, pregnancy, and aging shape the organs of the female reproductive tract and reveals the unexpected cost of the recurrent remodeling required for reproduction.

Sex-related exacerbation of injury-induced mechanical hypersensitivity in GAD67 haplodeficient mice

ABSTRACT

Decreased GABA levels in injury-induced loss of spinal inhibition are still under intense interest and debate. Here, we show that GAD67 haplodeficient mice exhibited a prolonged injury-induced mechanical hypersensitivity in postoperative, inflammatory, and neuropathic pain models. In line with this, we found that loss of 1 copy of the GAD67-encoding gene Gad1 causes a significant decrease in GABA contents in spinal GABAergic neuronal profiles. Consequently, GAD67 haplodeficient males and females were unresponsive to the analgesic effect of diazepam. Remarkably, all these phenotypes were more pronounced in GAD67 haplodeficient females. These mice had significantly much lower amount of spinal GABA content, exhibited an exacerbated pain phenotype during the second phase of the formalin test, developed a longer lasting mechanical hypersensitivity in the chronic constriction injury of the sciatic nerve model, and were unresponsive to the pain relief effect of the GABA-transaminase inhibitor phenylethylidenehydrazine. Our study provides strong evidence for a role of GABA levels in the modulation of injury-induced mechanical pain and suggests a potential role of the GABAergic system in the prevalence of some painful diseases among females.

Rapid Analysis of Estrogens in Meat Samples by High Performance Liquid Chromatography with Fluorescence Detection

A novel reagent named 4-(N-methyl-1,3-dioxo-benzoisoquinolin-6-yl-oxy)benzene sulfonyl chloride (MBIOBS-Cl) for the determination of estrogens in food samples by high-performance liquid chromatography (HPLC) with fluorescence detection has been developed. Estrogens could be easily labeled by MBIOBS-Cl in Na2CO3-NaHCO3 buffer solution at pH 10.0. The complete labeling reaction for estrogens could be accomplished within five minutes, the corresponding derivatives exhibited strong fluorescence with the maximum excitation and emission wavelengths at 249 nm and 443 nm, respectively. The derivatization conditions, such as the molar ratio of reagent to estrogens, derivatization time, pH, temperature, and buffers were optimized. Derivatives were sufficiently stable to be efficiently analyzed by HPLC with a reversed-phase Agilent ZORBAX 300SB-C18 column with a good baseline resolution. Excellent linear correlations were obtained for all estrogen derivatives with correlation coefficients greater than 0.9998. Ultrasonic-Assisted extraction was used to optimize the extraction of estrogens from meat samples with a recovery higher than 82%. The detection limits (LOD, S/N = 3) of the method ranged from 0.95 to 3.3 μg· kg-1. The established method, which is fast, simple, inexpensive, and environment friendly, can be successfully applied for the detection of four steroidal estrogens from meat samples with little matrix interference.

Female aging: when translational models don't translate

For many pathologies associated with aging, female patients present with higher morbidity and more frequent adverse events from treatments compared to male patients. While preclinical models are the foundation of our mechanistic understanding of age-related diseases, the most common models fail to recapitulate archetypical female aging trajectories. For example, while over 70% of the top age-related diseases are influenced by the systemic effects of reproductive senescence, we found that preclinical studies that include menopausal phenotypes modeling those seen in humans make up <1% of published aging biology research. The long-term impacts of pregnancy, birthing and breastfeeding are also typically omitted from preclinical work. In this Perspective, we summarize limitations in the most commonly used aging models, and we provide recommendations for better incorporating menopause, pregnancy and other considerations of sex in vivo and in vitro. Lastly, we outline action items for aging biology researchers, journals, funding agencies and animal providers to address this gap.

Abnormal Microglial Density and Morphology in the Brain of Cyclooxygenase 2 Knockin Mice

Prostaglandin E2 (PGE2) is a signaling molecule produced by cyclooxygenase-2 (COX-2) that is important in healthy brain development. Anomalies in the COX-2/PGE2 pathway due to genetic or environmental factors have been linked to Autism Spectrum Disorders (ASD). Our previous studies showed that COX-2 deficient (COX-2-KI) mice exhibit sex-dependent molecular changes in the brain and associated autism-related behaviors. Here, we aim to determine the effect of COX-2-KI on microglial density and morphology in the developing brain. Microglia normally transition between an amoeboid or ramified morphology depending on their surroundings and are important for the development of the healthy brain, assisting with synaptogenesis, synaptic pruning, and phagocytosis. We use COX-2-KI male and female mice to evaluate microglia density, morphology, and branch length and number in five brain regions (cerebellum, hippocampus, olfactory bulb, prefrontal cortex, and thalamus) at the gestational day 19 (G19) and postnatal day 25 (PN25). We discovered that COX2-KI females were affected at G19 with increased microglial density, altered percentage of amoeboid and ramified microglia, affected branch length, and decreased branching networks in a region-specific manner; these effects persisted to PN25 in select regions. Interestingly, while limited changes were found in G19 COX-2-KI males, at PN25 we found increased microglial density, higher percentages of ramified microglia, and increased branch counts, and length observed in nearly all brain regions tested. Overall, we show for the first time that the COX-2 deficiency in our ASD mouse model influences microglia morphology in a sex- and region- and stage-dependent manner.

Endocrine disruptors in Adansonia digitata (Linn) extract induce alteration of female Wistar rats' oestrous cycle, hormone and lipid profiles

OBJECTIVE

Hexane-acetyl acetate (HAAF) and acetyl acetate-methanol fractions (AAMF) but not aqueous methanol (AQMF) and aqueous fractions (AQF) of Adansonia digitata Linn root bark induce reproductive effects in female Wistar rats. The current study investigated the exclusive components of HAAF, AAMF, AQMF, and AQF of Adansonia digitata Linn root bark and the effect of AAMF on the female Wistar rat's oestrous cycle progression, and hormone and lipid profiles.

METHODOLOGY

Gas chromatography and mass spectrometry explored the components of HAAF, AAMF, AQMF, and AQF. Mature female Wistar rats with a proven 4-5-days oestrous cycle were synchronised and randomly assigned into three treatment groups of 30 rats each on the day of proestrus. For seven days, rats in the different groups received 0, 150, and 300 mg kg-1 body weights of AAMF, respectively. Six rats were euthanised from each group based on a standard oestrous stage-timed sequence. The oestrous stage, hormone profile (oestrogen, progesterone, progesterone/oestrogen ratio, and FSH) and lipid profile (Total cholesterol-TC, Triglycerols, High-HD and low density-LD lipid cholesterol) of the euthanised rats were determined.

RESULTS

tricosene, cyclopentadecanone 2-hydroxy-, oleic acid, and 9,17-octadecadienal, were exclusively found in HAAF and AAMF. The oestrous stage, serum hormone and lipids varied significantly (p < 0.05) between treatment groups. AAMF fraction induced sustained progesterone levels and depleted oestrogen levels, and TC and LDL were inversely related to serum oestrogen levels.

DISCUSSION

The results suggest a depression of oestrogen and sustenance of progesterone-mediated effects, respectively, on GnRH surge. Oleic acid in AAMF may be responsible for its reproductive effects.

CONCLUSION

AAMF fraction of A. digitata (L) root bark disrupts the endocrine activity in female Wistar rats. The oleic acid component of the AAMF fraction may be responsible for modulating the activities of reproductive hormones. The authors recommend further studies to ascertain the significance of Adansonia digitata extract's oleic acid in regulating the female reproductive cycle.

Cycling matters: Sex hormone regulation of vascular potassium channels

Sex hormones and the reproductive cycle (estrus in rodents and menstrual in humans) have a known impact on arterial function. In spite of this, sex hormones and the estrus/menstrual cycle are often neglected experimental factors in vascular basic preclinical scientific research. Recent research by our own laboratory indicates that cyclical changes in serum concentrations of sex -hormones across the rat estrus cycle, primary estradiol, have significant consequences for the subcellular trafficking and function of KV. Vascular potassium channels, including KV, are essential components of vascular reactivity. Our study represents a small part of a growing field of literature aimed at determining the role of sex hormones in regulating arterial ion channel function. This review covers key findings describing the current understanding of sex hormone regulation of vascular potassium channels, with a focus on KV channels. Further, we highlight areas of research where the estrus cycle should be considered in future studies to determine the consequences of physiological oscillations in concentrations of sex hormones on vascular potassium channel function.

Differential effects of acute stress on spatial learning and memory in the open-field tower maze across the female estrous cycle

The purpose of the present investigation was to test how acute stress and levels of circulating estrogens together influence acquisition and retention of spatial learning, as well as explorative behaviors in female rats. We used the hippocampus-dependent Open-field Tower Maze (OFTM) task to assess acquisition followed by a retention test (reacquisition) that was given 48 h later. Immediately prior to acquisition, experimental rats were exposed to an acute restraint stress and were trained under bright lights. Female rats' estrous cycles were tracked throughout training and testing. Exposure to stress did not affect learning when levels of estrogens were low (i.e., during estrus and metestrus). However, acute stress exposure significantly lowered spatial acquisition of the female rats in the phases with rising levels of estrogens (i.e., during diestrus and proestrus). Furthermore, this stress-induced diminishment during acquisition was evident at the beginning of the retention without any presentation of stress. The present findings provide insight about the interactive relationship between stress and sex hormones on cognitive functions.

Depleting transforming growth factor beta receptor 2 signalling in the cartilage of itga1-null mice attenuates spontaneous knee osteoarthritis

Objectives

Integrin α1β1 protects against osteoarthritis (OA) when it is upregulated in the superficial zone of cartilage in the early stages of disease. However, the mechanism behind this protection is unknown. Integrin α1β1 moderates transforming growth factor β receptor II (TGFBR2) signalling, a critical regulator of chondrocyte anabolic activity. To this end, mice lacking integrin α1β1 have increased baseline activation of TGFBR2 signalling and overall fibrosis. The purpose of this study was to evaluate the interplay between integrin α1β1 and TGFBR2 in the development of spontaneous OA. We hypothesized that dampening TGFBR2 signalling in the cartilage of itga1-null mice would attenuate OA.

Methods

Behavioural and histological manifestations of spontaneous knee OA were measured at 4, 8, 12 and 16 months in mice with and without a ubiquitous itga1 deletion and with and without a tamoxifen-induced cartilage specific TGFBR2 depletion.

Results

Knee cartilage degeneration, collateral ligament ossification and pain responses increased with age. Itga1-null mice with intact TGFBR2 signalling developed earlier and more severe OA compared to controls. In agreement with our hypothesis, depleting TGFBR2 signalling in the cartilage of itga1-null mice attenuated OA progression.

Conclusion

Intact TGFBR2 signalling drives early and worse knee OA in itga1-null mice. This result supports the hypothesis that the increased expression of integrin α1β1 by superficial zone chondrocytes early in OA development dampens TGFBR2 signalling and thus protects against degeneration.

A Novel Tissue-Specific Insight into Sex Steroid Fluctuations Throughout the Murine Estrous Cycle

Serum sex steroid levels fluctuate throughout the reproductive cycle. However, the degree to which sex steroid tissue content mimics circulating content is unknown. Understanding the flux and physiological quantity of tissue steroid content is imperative for targeted hormonal therapy development. Utilizing a gold-standard ultrasensitive liquid chromatography-mass spectrometry (LC/MS) method we determined sex steroid (17β-estradiol [E2], testosterone, androstenedione, and progesterone) fluctuations in serum and in 15 tissues throughout the murine estrous cycle (proestrus, estrus, and diestrus I) and in ovariectomized (OVX) mice. We observed dynamic fluctuations in serum and tissue steroid content throughout the estrous cycle with proestrus generally presenting the highest content of E2, testosterone, and androstenedione, and lowest content of progesterone. In general, the trend in circulating steroid content between the stages of the estrous cycle was mimicked in tissue. However, the absolute amounts of steroid levels when normalized to tissue weight were found to be significantly different between the tissues with the serum steroid quantity often being significantly lower than the tissue quantity. Additionally, we found that OVX mice generally displayed a depletion of all steroids in the various tissues assessed, except in the adrenal glands which were determined to be the main site of peripheral E2 production after ovary removal. This investigation provides a comprehensive analysis of steroid content throughout the estrous cycle in a multitude of tissues and serum. We believe this information will help serve as the basis for the development of physiologically relevant, tissue-specific hormonal therapies.

Serum DHEA and Testosterone Levels Associate Inversely With Coronary Artery Calcification in Elderly Men

CONTEXT

Epidemiological and preclinical data support cardiovascular, mainly protective, effects of sex steroids in men, but the mechanisms underlying the cardiovascular actions of sex steroids are poorly understood. Vascular calcification parallels the development of atherosclerosis, but is increasingly recognized as a diversified, highly regulated process, which itself may have pathophysiological importance for clinical cardiovascular events.

OBJECTIVE

To investigate the association between serum sex steroids and coronary artery calcification (CAC) in elderly men.

METHODS

We used gas chromatography tandem mass spectrometry to analyze a comprehensive sex steroid profile, including levels of dehydroepiandrosterone (DHEA), androstenedione, estrone, testosterone, estradiol, and dihydrotestosterone, in men from the population-based AGES-Reykjavik study (n = 1287, mean 76 years). Further, sex hormone-binding globulin (SHBG) was assayed and bioavailable hormone levels calculated. CAC score was determined by computed tomography. The main outcome measures were cross-sectional associations between dehydroepiandrosterone, androstenedione, estrone, testosterone, dihydrotestosterone, and estradiol and quintiles of CAC.

RESULTS

Serum levels of DHEA, androstenedione, testosterone, dihydrotestosterone, and bioavailable testosterone showed significant inverse associations with CAC, while estrone, estradiol, bioavailable estradiol, and SHBG did not. DHEA, testosterone, and bioavailable testosterone remained associated with CAC after adjustment for traditional cardiovascular risk factors. In addition, our results support partially independent associations between adrenal-derived DHEA and testes-derived testosterone and CAC.

CONCLUSION

Serum levels of DHEA and testosterone are inversely associated with CAC in elderly men, partially independently from each other. These results raise the question whether androgens from both the adrenals and the testes may contribute to male cardiovascular health.

Cycle-dependent sex differences in expression of membrane proteins involved in cerebrospinal fluid secretion at rat choroid plexus

BACKGROUND

Female sex is a known risk factor of brain disorders with raised intracranial pressure (ICP) and sex hormones have been suggested to alter cerebrospinal fluid (CSF) dynamics, thus impairing ICP regulation in CSF disorders such as idiopathic intracranial hypertension (IIH). The choroid plexus (CP) is the tissue producing CSF and it has been hypothesized that altered hormonal composition could affect the activity of transporters involved in CSF secretion, thus affecting ICP. Therefore, we aimed to investigate if expression of various transporters involved in CSF secretion at CP were different between males and females and between females in different estrous cycle states. Steroid levels in serum was also investigated.

METHODS

Female and male rats were used to determine sex-differences in the genes encoding for the transporters Aqp1 and 4, NKCC1, NBCe2, NCBE; carbonic anhydrase enzymes II and III (CA), subunits of the Na+/K+-ATPase including Atp1a1, Atp1b1 and Fxyd1 at CP. The estrous cycle stage metestrus (MET) and estrous (ES) were determined before euthanasia. Serum and CP were collected and subjected to RT-qPCR analysis and western blots. Serum was used to measure steroid levels using liquid chromatography tandem mass spectrometry (LC-MS/MS).

RESULTS

Significant differences in gene expression and steroid levels between males and ES females were found, while no differences were found between male and MET females. During ES, expression of Aqp1 was lower (p < 0.01) and NKCC1 was higher in females compared to males. CAII was lower while CAIII was higher in ES females (p < 0.0001). Gene expression of Atp1a1 was lower in ES compared to male (p = 0.0008). Several of these choroidal genes were also significantly different in MET compared to females in ES. Differences in gene expression during the estrus cycle were correlated to serum level of steroid hormones. Protein expression of AQP1 (p = 0.008) and CAII (p = 0.035) was reduced in ES females compared to males.

CONCLUSIONS

This study demonstrates for the first time that expression at CP is sex-dependent and markedly affected by the estrous cycle in female rats. Further, expression was related to hormone levels in serum. This opens a completely new avenue for steroid regulation of the expression of CSF transporters and the close link to the understanding of CSF disorders such as IIH.

Deconstructing sex: Strategies for undoing binary thinking in neuroendocrinology and behavior

The scientific community widely recognizes that "sex" is a complex category composed of multiple physiologies. Yet in practice, basic scientific research often treats "sex" as a single, internally consistent, and often binary variable. This practice occludes important physiological factors and processes, and thus limits the scientific value of our findings. In human-oriented biomedical research, the use of simplistic (and often binary) models of sex ignores the existence of intersex, trans, non-binary, and gender non-conforming people and contributes to a medical paradigm that neglects their needs and interests. More broadly, our collective reliance on these models legitimizes a false paradigm of human biology that undergirds harmful medical practices and anti-trans political movements. Herein, we continue the conversations begun at the SBN 2022 Symposium on Hormones and Trans Health, providing guiding questions to help scientists deconstruct and rethink the use of "sex" across the stages of the scientific method. We offer these as a step toward a scientific paradigm that more accurately recognizes and represents sexed physiologies as multiple, interacting, variable, and unbounded by gendered preconceptions. We hope this paper will serve as a useful resource for scientists who seek a new paradigm for researching and understanding sexed physiologies that improves our science, widens the applicability of our findings, and deters the misuse of our research against marginalized groups.

The tremendous clinical potential of the microbiota in the treatment of breast cancer: the next frontier

Although significant advances have been made in the diagnosis and treatment of breast cancer (BC) in recent years, BC remains the most common cancer in women and one of the main causes of death among women worldwide. Currently, more than half of BC patients have no known risk factors, emphasizing the significance of identifying more tumor-related factors. Therefore, we urgently need to find new therapeutic strategies to improve prognosis. Increasing evidence demonstrates that the microbiota is present in a wider range of cancers beyond colorectal cancer. BC and breast tissues also have different types of microbiotas that play a key role in carcinogenesis and in modulating the efficacy of anticancer treatment, for instance, chemotherapy, radiotherapy, and immunotherapy. In recent years, studies have confirmed that the microbiota can be an important factor directly and/or indirectly affecting the occurrence, metastasis and treatment of BC by regulating different biological processes, such as estrogen metabolism, DNA damage, and bacterial metabolite production. Here, we review the different microbiota-focused studies associated with BC and explore the mechanisms of action of the microbiota in BC initiation and metastasis and its application in various therapeutic strategies. We found that the microbiota has vital clinical value in the diagnosis and treatment of BC and could be used as a biomarker for prognosis prediction. Therefore, modulation of the gut microbiota and its metabolites might be a potential target for prevention or therapy in BC.