FSH blockade improves cognition in mice with Alzheimer's disease

Gene-dose-dependent reduction of Fshr expression improves spatial memory deficits in Alzheimer's mice

High post-menopausal levels of the pituitary gonadotropin follicle-stimulating hormone (FSH) are strongly associated with the onset of Alzheimer's disease (AD). We have shown recently that FSH directly activates the hippocampal FSH receptors (FSHRs) to drive AD-like pathology and memory loss in mice. To unequivocally establish a role for FSH in memory loss, we depleted the Fshr on a 3xTg background and utilized Morris Water Maze to study deficits in spatial memory. 3xTg;Fshr+/+ mice displayed impaired spatial memory at 5 months of age. The loss of memory acquisition and retrieval were both rescued in 3xTg;Fshr-/- mice and, to a lesser extent, in 3xTg;Fshr+/- mice-documenting clear gene-dose-dependent prevention of spatial memory loss. Furthermore, at 5 and 8 months, sham-operated 3xTg;Fshr-/- mice showed better memory performance during the learning and/or retrieval phases, further suggesting that Fshr deletion prevents age-related progression of memory deficits. This prevention was not seen when mice were ovariectomized, except in the 8-month-old 3xTg;Fshr-/- mice. There was also a gene-dose-dependent reduction mainly in the amyloid β40 isoform in whole brain extracts. Finally, serum FSH levels <8 ng/mL in 16-month-old APP/PS1 mice were associated with better retrieval of spatial memory. Collectively, the data provide compelling genetic evidence for a protective effect of inhibiting FSH signaling on the progression of spatial memory deficits in mice and lay a firm foundation for the use of an FSH-blocking agent for the early prevention of memory loss in post-menopausal women.

Gut microbiota-mediated choline metabolism exacerbates cognitive impairment induced by chronic cerebral hypoperfusion

Chronic cerebral hypoperfusion (CCH) is a crucial mechanism causing vascular cognitive impairment (VCI). Choline is metabolized by gut microbiota into trimethylamine N-oxide (TMAO), a risk factor of cardiovascular diseases and cognitive impairment. However, the impact of choline-TMAO pathway on CCH-induced VCI is elusive. We performed a cross-sectional clinical study to investigate the relationship between the choline-TMAO pathway and cognitive outcome and used a bilateral common carotid artery occlusion rat model to explore the effect of a choline-rich diet on cognition and underlying mechanisms. Plasma choline and TMAO levels were negatively correlated with cognitive scores in CCH patients. A choline-rich diet exacerbated CCH-induced cognitive impairment by encouraging the proliferation of choline-metabolizing bacteria in the gut and subsequent generation of TMAO. The choline-TMAO pathway, mediated by gut microbiota, exacerbates cognitive impairment induced by CCH. Targeted dietary choline regulation based on gut microbiota modulation may ameliorate long-term cognitive impairment.

Host-Microbial Cometabolite Ursodeoxycholic Acid Protects Against Poststroke Cognitive Impairment

BACKGROUND

Poststroke cognitive impairment (PSCI) is a common residual disability after stroke, often underestimated and underdiagnosed. We previously found that ursodeoxycholic acid (UDCA), a host-microbiota cometabolite, ameliorates brain damage in stroke mice. Based on these findings, we aimed to evaluate the predictive value of UDCA for PSCI risk in a prospective cohort study.

METHODS AND RESULTS

We recruited 202 patients with mild acute ischemic stroke and 63 patients with symptomatic large-artery atherosclerotic stenosis as the modeling and external validation cohorts, respectively. Mice were subjected to transient middle cerebral artery occlusion, and cognitive function was assessed using the Morris water maze test. Patients with mild acute ischemic stroke who developed PSCI exhibited significant alterations in gut microbiota and plasma bile acid profiles during the acute stroke phase, including a notable reduction in UDCA level. Through feature selection and machine learning, we constructed a predictive model for PSCI incorporating plasma UDCA level, the relative abundance of Clostridia, Bacilli, and Bacteroides, as well as age, educational level, and the presence of moderate to severe white matter lesions. This model exhibited robust predictive performance in both internal (area under the curve, 0.904 [95% CI, 0.808-1.000]) and external (area under the curve, 0.838 [95% CI, 0.742-0.934]) validations. Animal studies in mice also showed reduced UDCA levels in plasma and brain tissue following stroke. UDCA administration improved cognitive function in stroke mice by reducing hippocampal microglial activation and neuronal apoptosis.

CONCLUSIONS

Our findings indicate that UDCA has potential as a biomarker for predicting PSCI risk and plays a neuroprotective role in the progression of PSCI. This suggests that early identification and intervention targeting UDCA could represent a promising strategy for the prevention and treatment of PSCI.

Differences in transcriptome characteristics and drug repositioning of Alzheimer's disease according to sex

BACKGROUND

Previous studies have shown significant sex differences in AD with regarding its epidemiology, pathophysiology, clinical presentation, and treatment response. However, the transcriptome variances associated with sex in AD remain unclear.

METHODS

RNA sequencing (RNA-seq) and transcriptomic analyses were performed on peripheral blood samples from total of 54 patients, including male AD patients (n = 15), female AD patients (n = 10), male MCI patients (n = 7), female MCI patients (n = 11), male healthy controls (n = 6), female healthy controls (n = 5). The snRNA-seq dataset (GSE167494, GSE157827) of prefrontal cortex tissues was obtained from the Gene Expression Omnibus (GEO). We conducted an investigation into differentially expressed genes and pathways in the peripheral blood cells as well as prefrontal cortex tissues of both male and female AD patients with consideration to sex-related factors. Additionally, we analyzed the distribution and characteristics of cells in the cerebral cortex as well as the interaction and communication between cells of male and female AD patients. Connectivity Map (CMap) was utilized for predicting and screening potential sex-specific drugs for AD.

RESULTS

The transcriptome profile and associated biological processes in the peripheral blood of male and female AD and MCI patients exhibit discernible differences, including upregulation of BASP1 in AD male patients and arousing TNS1 in AD female patients. The distribution of various cell types in the prefrontal cortex tissues differs between male and female AD patients, like neuron and oligodendrocyte decreased and endothelial cell and astrocyte increased in female compared with male, while a multitude of genes exhibit significant differential expression. The results of cell communication analysis, such as collagen signaling pathway, suggest that sex disparities impact intercellular interactions within prefrontal cortex tissues among individuals with AD. By drug repositioning, several drugs, including torin-2 and YM-298198, might have the potential to therapeutic value of MCI or AD, while drugs like homoharringtonine and teniposide have potential opposite effects in different sexes.

CONCLUSION

The characteristics of the transcriptome in peripheral blood and single-cell transcriptome in the prefrontal cortex exhibit significant differences between male and female patients with AD, which providing a basis for future sex stratified treatment of AD.

Liquid-liquid phase separation of RBM33 facilitates hippocampus aging by inducing microglial senescence by activating CDKN1A

Microglia play an important role in hippocampus-dependent memory and cognitive function. Microglial aging contributes to hippocampal aging and influences neurodegenerative diseases, although the underlying mechanisms remain unclear. RBM33 was highly expressed in the hippocampus of naturally aged mice and senescent microglia. Hippocampus-specific genetic deletion of RBM33 alleviated age-related declines in learning and memory in aged RBM33 knockout (RBM33-/-) mice. In contrast, hippocampus-specific overexpression of RBM33 exacerbated these declines in aged RBM33 overexpression (RBM33Tg) mice, indicating that RBM33 acts as an age-promoting factor in the hippocampus. Mechanistically, RBM33 forms liquid-liquid phase separation (LLPS) both in vitro and in cells. RBM33 LLPS is required for its binding to the CDKN1A (p21cip1) promoter in a non-canonical transcriptional regulatory manner, leading to hippocampus-dependent declines in learning and memory by inducing microglial senescence. This study reveals that the RBM33 LLPS/ p21cip1 axis facilitates brain aging by inducing microglial senescence. Targeting the RBM33 LLPS/ p21cip1 axis may represent a therapeutic strategy to mitigate microglia senescence-mediated brain aging and hippocampus-dependent cognitive decline.

Critical illness and sex hormones: response and impact of the hypothalamic-pituitary-gonadal axis

Understanding the hypothalamic-pituitary-gonadal (HPG) axis is essential for grasping human responses under extreme physiological and pathological conditions. The HPG axis regulates reproductive and gonadal hormone activities and significantly impacts the body's response to acute and chronic illnesses. This review explores the fundamental functions of the HPG axis, modifications under critical conditions, and impacts on disease progression and treatment outcomes. In addition, it examines interactions between sex hormones and biomolecules like cytokines and gastrointestinal microorganisms, highlighting their roles in immune response regulation. Clinically, this knowledge can enhance patient prognoses. The review aims to provide a comprehensive framework, based on existing research, for understanding and applying the functions of the HPG axis in managing critical diseases, thereby broadening clinical applications and guiding future research.

Ovarian Endometriosis Accelerates Premature Ovarian Failure and Contributes to Osteoporosis and Cognitive Decline in Aging Mice

Ovarian endometriosis (OEM) is a chronic inflammatory condition that impairs ovarian function. While its effects on ovarian reserve are well established, the long-term consequences of OEM on ovarian dysfunction, premature ovarian failure (POF), and systemic health, particularly in the context of accelerated aging, remain insufficiently studied. In this study, we employed an OEM mouse model and bulk RNA sequencing to investigate the underlying mechanisms. Our results show that OEM accelerates primordial follicle depletion and upregulates mTOR signaling pathway gene expression, along with mechanical stress and paracrine signaling via the Hippo and Myc pathways. OEM also induces irregular estrus and ovarian fibrosis in aging mice, decreases serum AMH levels, and increases FSH levels. Systemically, elevated serum IgG levels contribute to osteoporosis and cognitive decline, both linked to ovarian dysfunction and POF in OEM. These findings elucidate the mechanisms driving premature ovarian reserve depletion in OEM and highlight its broader systemic effects. This study emphasizes the importance of monitoring ovarian health and ectopic tissue to safeguard ovarian reserves and mitigate long-term risks such as osteoporosis and cognitive decline.

FSH exacerbates bone loss by promoting osteoclast energy metabolism through the CREB-MDH2-NAD+ axis

AIMS

Osteoclast energy metabolism is a promising target for treating diseases characterized by high osteoclast activity, such as osteoporosis. However, the regulatory factors involved in osteoclast bioenergetic processes are still in the early stages of being fully understood. This study reveals the effects of follicle-stimulating hormone (FSH) on osteoclast energy metabolism.

METHODS

The Lyz2-Cre-Flox model selectively deletes FSH receptor (FSHR) from osteoclast precursor cells to generate Fshrf/f; Lyz2-Cre (Fshrf/f; Cre) mice. Bone quality was assessed using micro-computed tomography, histomorphometric analysis, and dual-fluorescence labeling. The in vitro assays measured oxygen consumption rate, extracellular acidification rate, pyruvate content, and mitochondrial membrane potential to determine metabolic flux. RNA-seq, LC-MS, dual-luciferase reporter assays, and chromatin immunoprecipitation (ChIP) assays were used to elucidate the underlying mechanisms.

RESULTS

FSHR deficiency in osteoclasts protected bone from resorption under normal and ovariectomized conditions. FSHR-deficient osteoclasts have reduced nicotinamide adenine dinucleotide (NAD+) levels, impairing osteoclast activity and energy metabolism. Mechanistically, FSH influenced NAD+ levels via the CREB/MDH2 axis. Treatment with FSH monoclonal antibodies rescued bone loss in OVX mice and reduced bone marrow NAD+ levels.

CONCLUSIONS

Targeting FSH may be a promising metabolic modulation strategy for treating osteoporosis and other diseases associated with high osteoclast activity.

Disease Burden, Temporal Trends, and Cross-Country Inequality Associated with Sociodemographic Indicators in Alzheimer's Disease and Other Dementias

INTRODUCTION

The purpose of this article is to describe the global burden and temporal trends of Alzheimer's disease and other dementias from 1990 to 2021 and explore cross-country inequality associated with sociodemographic development-related factors.

METHODS

The disability-adjusted life years of Alzheimer's disease and other dementias and sociodemographic index were extracted from the Global Burden of Disease 2021 study, and other sociodemographic development-related factors, including government expenditure on education (% of GDP), net national income per capita, health expenditure per capita, and fertility rate, were sourced from World Bank Data. Disability-adjusted life years of Alzheimer's disease and other dementias across 204 countries/territories and global age-sex distribution in 2021 were illustrated. The Joinpoint regression model was used to analyze the temporal trends of disease burden, and the slope index of inequality and concentration index were calculated to quantify cross-country inequalities. Analyses were conducted in 2024.

RESULTS

Significant disparities were observed in the numbers, rates, and age-standardized rates of disability-adjusted life years across 204 countries/territories. Females demonstrated higher disability-adjusted life year numbers (rates) for all age groups. Age-standardized disability-adjusted life year rate increased worldwide and was high in high-middle and middle sociodemographic index regions but increased faster in low (average annual percentage change=0.227%) and low-middle (average annual percentage change=0.244%) sociodemographic index regions. Cross-country inequality analyses indicated that disability-adjusted life years of Alzheimer's disease and other dementias were skewed and higher in countries with higher sociodemographic development, and the inequality increased with time except for education expenditure-related inequality.

CONCLUSIONS

The burden of Alzheimer's disease and other dementias has risen globally over the past 3 decades, accompanied by increasing cross-country inequalities, which disproportionately affects countries with high sociodemographic development. Boosting expenditure on education may narrow this inequality.

Development of asparagine endopeptidase inhibitors for treating neurodegenerative diseases

Asparagine endopeptidase (AEP), or legumain, is a cysteine protease implicated in various disorders, including atherosclerosis, cancers, neurodegenerative diseases, and inflammation. The development of AEP inhibitors has emerged as a promising therapeutic strategy to modulate AEP activity and slow disease progression. Various AEP inhibitors have been explored, encompassing small molecules, peptide-based, antibody-based, and natural inhibitors. Substrate-mimetic and covalent inhibitors show significant potential for selectively targeting AEP's active site, whereas noncovalent inhibitors offer reversible modulation. Additionally, FDA-approved drugs have also garnered attention for their diverse structures and multitarget capabilities. In this review, we summarize advancements in AEP inhibitors, their mechanisms of action, therapeutic applications in neurodegenerative diseases, and the challenges in translating these findings into clinical practice.

Association Between Serum Follicle-Stimulating Hormone Levels and Cognitive Function in Middle-Aged and Older Women

BACKGROUND

Researchers have proposed that there is a potential link between follicle-stimulating hormone (FSH) and cognitive function, yet the evidence remains inconclusive. The current study aims to identify the association between serum FSH levels and cognitive performance, and to examine whether this association varies by cognitive diagnosis, serum estradiol (E2) levels, or cognitive domain.

METHODS

This multicenter cross-sectional study used a clinical database comprising female visitors to memory clinics at three referral hospitals in Korea. Venous blood samples were collected to determine serum FSH and E2 concentrations via immunoradiometric assay. Cognitive performance was evaluated using either the Korean version of the Consortium to Establish a Registry for Alzheimer's Disease or the Seoul Neuropsychological Screening Battery, while cognitive diagnoses were made via clinical diagnostic interviews.

RESULTS

Among the 159 participants (normal cognition [NC], n = 70; mild cognitive impairment [MCI], n = 52; Alzheimer's disease [AD] dementia, n = 37), there were no significant differences in serum FSH levels associated with cognitive diagnosis. In women with NC, serum FSH levels were found to be positively correlated with cognitive performance in global cognition, nonverbal memory, and executive function, even after adjusting for serum E2 level and its interaction with serum FSH level. However, no significant correlations were observed in women with MCI and AD dementia.

CONCLUSION

The association between circulating FSH and cognition may be independent from circulating E2, but it may depend on disease progression or cognitive domains. This suggests a potential role of gonadotropin in cognitive decline in elderly women.

The global, regional, and national burdens of dementia in 204 countries and territories from 1990 to 2021: A trend analysis based on the Global Burden of Disease Study 2021

The global population is aging, and as a consequence, the prevalence of dementia is increasing rapidly. This study aims to analyze trends in the Global Burden of Disease (GBD) and health inequalities for dementia over the period 1990 to 2021. The incidence, prevalence, and disability-adjusted life year rates of dementia in the GBD 2021 database were analyzed at the global, national, and regional levels for the period 1990 to 2021 using Joinpoint 4.9.1.0 software. The trends over the period were assessed using a combination of age-standardized rates, average annual percentage changes (AAPCs), and a sociodemographic index. The analysis revealed that, from 1990 to 2021, the global AAPC in dementia incidence, prevalence, and disability-adjusted life years amounted to 0.06 (95% confidence interval [CI]: 0.05-0.09), 0.09 (95% CI: 0.08-0.10), and 0.03 (95% CI: 0.01-0.05), respectively. Conversely, the mean AAPC in age-standardized mortality rate remained stable at 0 (95% CI: -0.02 to 0.03). The age-standardized incidence rate and age-standardized prevalence rate of dementia exhibited a positive association with sociodemographic index during the study period. The 3 regions with the highest mean AAPC in age-standardized mortality rate among the 21 GBD regions were South Africa, Central Sub-Saharan Africa, and Eastern Sub-Saharan Africa. The findings of the study indicate that the burden of dementia increases with age and is projected to remain on an upward trend until 2040. The GBD has increased significantly from 1990 to 2021, and the prevention and control of dementia represents a long-term and formidable challenge.

Sex chromosomes and gonads modify microglial-mediated pathology in a mouse model of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder disproportionally affecting women with sex-specific disease manifestations and therapeutic responses. Microglial-mediated inflammation occurs in response to and perpetuates disease processes, and fundamental sex differences in microglia may contribute to these sex biases. Both sex chromosomes and gonad-derived hormones shape immune responses, but their contribution to immune-mediated mechanisms underlying the sex bias in AD is unclear. Crossing the Four Core Genotype (FCG) model to separate sex chromosome and gonad-derived hormone effects to the 5xFAD model, we found the sex chromosome complement impacted microgliosis, neuroinflammation, plaque burden and neuritic dystrophy. Modification of pathology largely correlated with microgliosis, and sex chromosomes and gonad-derived hormones influenced plaque remodeling and microglial CD11c expression. Our results provide potential trajectories for studying and targeting microglial-mediated sex differences and emphasize the complex interplay between sex chromosomes and hormones during AD.

Associations between hormone therapy use and tau accumulation in brain regions vulnerable to Alzheimer's disease

Elucidating the downstream impact of exogenous hormones on the aging brain will have far-reaching consequences for understanding why Alzheimer's disease (AD) predominates in women almost twofold over men. We tested the extent to which menopausal hormone therapy (HT) use is associated with later-life amyloid-β (Aβ) and tau accumulation using PET on N = 146 baseline clinically normal women, aged 51 to 89 years. Women were scanned over a 4.5-year (SD, 2.1; range, 1.3 to 10.4) and 3.5-year (SD, 1.5; range, 1.2 to 8.1) period for Aβ and tau, respectively, ~14 years after the initiation of HT. In older women (aged >70 years), HT users exhibited faster regional tau accumulation relative to non-users, localized to the entorhinal cortex and the inferior temporal and fusiform gyri, with an indirect effect of HT on cognitive decline through regional tau accumulation. In younger women (aged <70 years), HT associations with tau accumulation were negligible. Findings are relevant for optimizing menopausal treatment guidelines.

Sex differences in age-associated neurological diseases-A roadmap for reliable and high-yield research

Once taken into consideration, sex differences in neurological diseases emerge in abundance: (i) Stroke severity is significantly higher in females than in males, (ii) Alzheimer's disease (AD) pathology is more pronounced in females, and (iii) conspicuous links with hormonal cycles led to female-specific diagnoses, such as catamenial migraines and epilepsy. While these differences receive increasing attention in isolation, they likely link to similar processes in the brain. Hence, this review aims to present an overview of the influences of sex chromosomes, hormones, and aging on male and female brains across health and disease, with a particular focus on AD and stroke. The focus here on advancements across several fields holds promise to fuel future research and to lead to an enriched understanding of the brain and more effective personalized neurologic care for all.

ApoE3 R136S binds to Tau and blocks its propagation, suppressing neurodegeneration in mice with Alzheimer's disease

PSEN1 E280A carrier for the APOE3 Christchurch variant (R136S) is protected against Alzheimer's disease (AD) symptoms with a distinct anatomical pattern of Tau pathology. However, the molecular mechanism accounting for this protective effect remains incompletely understood. Here, we show that the ApoE3 R136S mutant strongly binds to Tau and reduces its uptake into neurons and microglia compared with ApoE3 wild type (WT), diminishing Tau fragmentation by asparagine endopeptidase (AEP), proinflammatory cytokines by Tau pre-formed fibrils (PFFs) or β-amyloid (Aβ), and neurotoxicity. Further, ApoE3 R136S demonstrates more robust effects in attenuating AEP activation and Tau PFF spreading in the brains of both 5xFAD and Tau P301S mice than in ApoE3 WT, leading to improved cognitive functions. Thus, our findings support the idea that ApoE3 R136S strongly binds Tau and decreases its cellular uptake, abrogating Tau pathology propagation in AD brains.

Sex Differences in Longitudinal Tau-PET in Preclinical Alzheimer Disease: A Meta-Analysis

Importance

Alzheimer disease (AD) predominates in females at almost twice the rate relative to males. Mounting evidence in adults without AD indicates that females exhibit higher tau deposition than age-matched males, particularly in the setting of elevated β-amyloid (Aβ), but the evidence for sex differences in tau accumulation rates is inconclusive.

Objective

To examine whether female sex is associated with faster tau accumulation in the setting of high Aβ (as measured with positron emission tomography [PET]) and the moderating influence of sex on the association between APOEε4 carrier status and tau accumulation.

Data Sources

This meta-analysis used data from 6 longitudinal aging and AD studies, including the Alzheimer's Disease Neuroimaging Initiative, Berkeley Aging Cohort Study, BioFINDER 1, Harvard Aging Brain Study, Mayo Clinic Study of Aging, and Wisconsin Registry for Alzheimer Prevention. Longitudinal data were collected between November 2004 and May 2022.

Study Selection

Included studies required available longitudinal [18F]flortaucipir or [18F]-MK-6240 tau-PET scans, as well as baseline [11C] Pittsburgh Compound B, [18F]flutemetamol or [18F]florbetapir Aβ-PET scans. Recruitment criteria varied across studies. Analyses began on August 7, 2023, and were completed on February 5, 2024.

Data Extraction and Synthesis

In each study, primary analyses extracted estimates for the sex (female or male) and the sex by baseline Aβ-PET status (high or low) association with longitudinal tau-PET using a series of mixed-effects models. Secondary mixed-effects models extracted the interaction estimate for the association of sex by APOEε4 carrier status with longitudinal tau-PET. Study-specific estimates for each mixed-effects model were then pooled in a meta-analysis, and the global fixed effect (β) and total heterogeneity (I2) across studies were estimated. This study is reported following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline.

Main Outcomes and Measures

Seven tau-PET outcomes that showed cross-sectional sex differences were examined across temporal, parietal, and occipital lobes.

Results

Among 6 studies assessed, there were 1376 participants (761 [55%] female; mean [range] age at first tau scan, 71.9 [46-93] years; 401 participants [29%] with high baseline Aβ; 412 APOEε4 carriers [30%]). Among individuals with high baseline Aβ, female sex was associated with faster tau accumulation localized to inferior temporal (β = -0.14; 95% CI, -0.22 to -0.06; P = .009) temporal fusiform (β = -0.13; 95% CI, -0.23 to -0.04; P = .02), and lateral occipital regions (β = -0.15; 95% CI, -0.24 to -0.06; P = .009) compared with male sex. Among APOEε4 carriers, female sex was associated with faster inferior-temporal tau accumulation (β = -0.10; 95% CI, -0.16 to -0.03; P = .01).

Conclusions and Relevance

These findings suggest that sex differences in the pathological progression of AD call for sex-specific timing considerations when administrating anti-Aβ and anti-tau treatments.

Subclinical Hyperthyroidism Enhances Gonadotropin-Lowering Effects of Metformin in Postmenopausal Women

Metformin treatment decreases elevated concentrations of anterior pituitary hormones. The aim of this prospective, cohort study was to investigate whether hyperthyroidism modulates the impact of metformin on gonadotroph secretory function. The study population included 48 postmenopausal women with untreated type 2 diabetes or prediabetes, 24 of whom had coexisting grade 1 subclinical hyperthyroidism. Both groups were matched for age, insulin sensitivity, and gonadotropin levels. Over the entire study period, all participants were treated with metformin (2.55-3 g daily). Plasma glucose, insulin, thyroid-stimulating hormone (TSH), total and free thyroid hormones, follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol, prolactin, adrenocorticotropic hormone (ACTH), and insulin-like growth factor-1 (IGF-1) were assayed at entry and 6 months later. At baseline, the study groups differed in levels of TSH and thyroid hormones but not in body mass index, blood pressure, glucose homeostasis markers (fasting glucose, homeostatic model assessment 1 of insulin resistance ratio [HOMA1-IR], and glycated hemoglobin [HbA1c]), and the remaining hormones. There were no differences between both groups in the degree of reduction in plasma glucose and HbA1c in response to metformin treatment. Although metformin decreased HOMA1-IR in both groups, this effect was stronger in women with hyperthyroidism than with normal thyroid function (-50 ± 20% vs -30 ± 15%). Similar relationships were observed for FSH (-43 ± 21% vs -21 ± 12%). Only in hyperthyroid women did the drug reduce LH concentration (by 35 ± 17%). Metformin did not affect circulating levels of TSH, total and free thyroxine, total and free triiodothyronine, estradiol, prolactin, ACTH, and IGF-1. The obtained results indicate that hyperthyroidism enhances the gonadotropin-lowering effects of metformin, as well as the fact that this agent has a neutral effect on the hypothalamic-pituitary-thyroid axis in case of its overactivity.

Follicle-stimulating hormone: More than a marker for menopause: FSH as a frontier for women's mental health

The average current life expectancy entails that women will spend over one-third of their lives in menopause. Follicle-stimulating hormone (FSH) levels in women begin to increase roughly six years before the final menstrual period, reaching a menopausal plateau that is nearly 14 times the level of FSH observed in men, a profound sex-specific difference. A promising new body of work examines whether these age-associated increases in FSH contribute to multiple menopause-related conditions, including psychiatric morbidities. This paper highlights research advances showing the potential role of FSH and its underlying mechanisms in mental health conditions for women in menopause and makes the call for more research.

Brain structural alterations in young women with premature ovarian insufficiency: Implications for dementia risk

INTRODUCTION

Premature ovarian insufficiency (POI), marked by ovarian function loss before age 40, is linked to a higher risk of dementia, including Alzheimer's disease (AD). However, the associated brain structural changes remain poorly understood.

METHODS

We analyzed T1-weighted and diffusion tensor imaging in 33 idiopathic POI women and 51 healthy controls, using voxel-based, surface-based morphometry, and network analyses to assess gray matter volume (GMV), cortical thickness, and brain connectivity.

RESULTS

Women with POI showed significant GMV and cortical thickness reductions in the frontal, parietal, and temporal regions (p < 0.05), alongside impaired connectivity with key regions such as the hippocampus, thalamus, and amygdala (p < 0.05). Younger POI subgroups exhibited changes in more widespread brain regions. In additionally, notable atrophy was observed in specific hippocampal and thalamic subregions in POI (p < 0.05).

DISCUSSION

This preliminary study suggests early neurodegenerative patterns in POI, potentially contributing to dementia risk. Further research is needed to explore the underlying mechanisms and potential interventions.

HIGHLIGHTS

We evaluated brain structural changes in participants with idiopathic premature ovarian insufficiency (POI). The observed brain alterations in POI participants closely resemble those seen in early dementia, including regions specifically associated with Alzheimer's disease (AD). These findings highlight the critical need for early interventions to reduce the long-term risks of cognitive impairment and dementia in women with POI.

Asparagine Endopeptidase Inhibition Attenuates Tissue Plasminogen Activator-Induced Brain Hemorrhagic Transformation After Ischemic Stroke

BACKGROUND

Thrombolytic treatment with tissue plasminogen activator (tPA) is one of the approved pharmacological therapies for acute ischemic stroke. However, the use of tPA is limited due to hemorrhagic transformation (HT) and the narrow therapeutic time window. Previous studies demonstrated that asparagine endopeptidase (AEP), a widely expressed pH-dependent endo-lysosomal cysteine protease, can induce neuronal death during ischemia-reperfusion injury. But whether AEP is engaged in HT during ischemia-reperfusion injury is unclear. In the current study, we expanded the role of AEP on HT after delayed tPA administration.

METHODS

In order to investigate the effects of AEP on HT after delayed tPA administration following ischemic stroke, the middle cerebral artery occlusion/reperfusion (MCAO/R) was performed in wild-type (WT) and AEP knockout (KO) transgenic mice, followed by delayed administration of tPA (10 mg/kg, 3 h after occlusion). Additionally, we explored the potential of R13, a specific TrkB agonist with a strong inhibitory impact on AEP, to mitigate injury induced by tPA. 24 h after tPA administration, the following parameters were assessed: infarct volume, behavioral tests, hemorrhagic levels, Evans blue leakage, tight and adherens junction protein expression, blood-brain barrier (BBB) function, cerebral vascular structure, matrix metalloproteinases (MMPs), and BBB-regulated protein low-density lipoprotein receptor-related protein 1 (LRP-1) expression. To construct an in vitro model to examine the effects of AEP on ischemia-reperfusion injury after tPA treatment, human umbilical vein endothelial cells (HUVECs) were exposed to 4 h of oxygen-glucose deprivation (OGD), followed by treatment with tPA (500 ng/mL). 7,8-dihydroxyflavone (7,8-DHF), a natural TrkB agonist with an inhibitory effect on AEP, was applied before OGD.

RESULTS

Compared with tPA-treated WT mice, AEP KO mice treated with tPA showed improved infarct volume, neurological function, brain edema, brain hemoglobin levels, Evans blue leakage, vascular tight junctions, and basement membrane structure combined with reduced AEP expression and activity within the peri-infarct area. In addition, the mice treated with R13 exhibited protective effects on the BBB. Furthermore, we found that the expression of MMP2, MMP9, and LRP-1 in the brain was inhibited by both AEP knockout and R13 treatment. Moreover, HUVECs treated with 7,8-DHF showed improvements in tight and adherens junction proteins and suppressed levels of MMP2, MMP9, and LRP-1.

CONCLUSION

Our findings demonstrate that AEP exacerbates HT induced by delayed tPA treatment in acute ischemic stroke by activating LRP-1, MMP2, and MMP9, which disrupts BBB integrity. We further confirmed R13 as a preventive therapy to attenuate HT induced by delayed tPA treatment in acute ischemic stroke. The present study suggests AEP inhibition may serve as a promising strategy to enhance the safety of delayed tPA thrombolysis for ischemic stroke.

Carboxylated Zn-phthalocyanine attenuates brain Aβ in AD model mouse

The deposition of aggregated amyloid β (Aβ) is considered as a key factor for Alzheimer's Disease (AD). Previously, we demonstrated that a carboxylated Zn-phthalocyanine (ZnPc) inhibits Aβ fibril formation, consequently protects neurons in culture. This study evaluated the effects of ZnPc on pathological changes in an AD mouse model (J20). Nine-month-old J20 mice received weekly intraperitoneal injection of ZnPc (2 and 4 mg/kg) for 12 weeks. Cognitive performance was assessed using Y-maze and open field tests. ZnPc levels in the tissues were evaluated using near-infrared microscopy and spectroscopy. ZnPc accumulated primarily in the liver and kidney. A considerable amount was also detected in brain tissue, where it co-localized with neurons, microglia, and extracellularly deposited Aβ. ZnPc treatment (2 mg/kg) significantly improved cognitive functions of J20 mice. Immunostaining results showed that Aβ was positive intracellularly in neurons, and extracellularly around the vessels and parenchyma in the cortex and hippocampus of PBS-treated J20 mice, which was significantly decreased in ZnPc-treated J20 mice in a dose-dependent manner. Nissl staining demonstrated that neuronal numbers were increased both in the cortex and hippocampus. GFAP-positive astrocytes and Iba-1 positive microglia were decreased by ZnPc treatment. Also, vessel numbers were increased in ZnPc-treated groups. In PBS-treated group, aquaporin 4 immunopositive area extended beyond STL-positive vessels into the parenchyma, which was confined primarily around the vessels in the ZnPc-treated group. Claudin 5 levels were increased in ZnPc-treated group. Therefore, ZnPc can decrease brain Aβ deposition in J20 mice, suggesting it as a potential therapeutic agent for AD.

GnRH and Cognition

GnRH is traditionally recognized as the central regulator of reproduction through its pulsatile secretion, which governs the hypothalamic-pituitary-gonadal axis. However, recent evidence has highlighted its broader role in brain development and function, including in cognitive and higher intellectual processes. GnRH production follows distinct phases, from its early activation during minipuberty-the first postnatal activation of GnRH neurons during the infantile period-, its reactivation and stabilization starting at puberty, and its eventual decline with age and the loss of gonadal steroid feedback. This evolution depends on the establishment, maturation and activation of GnRH neurons, a complex process regulated by the cellular and molecular environment of these neurons, including multiple neuronal and glial types as well as a minipubertal "switch" in gene expression, the perturbation of which may have long-term or delayed consequences for both reproductive and cognitive function. The cognitive role of GnRH may be related to its recently revealed involvement in maintaining myelination and synaptic plasticity, whereas disruptions in its finely tuned rhythmic secretion, either age-related or pathological, are associated with cognitive decline and neurodegenerative disorders. Restoring physiological GnRH levels and pulsatility can reverse age-related cognitive decline and improve sensory functions even in adulthood, suggesting a mobilization of the "cognitive reserve" in both animal models and human patients. This review highlights recent advances in our understanding of the GnRH system and the therapeutic potential of pulsatile GnRH therapy to mitigate age-related cognitive decline and neurodegenerative processes.

Estropausal gut microbiota transplant improves measures of ovarian function in adult mice

Decline in ovarian function with age not only affects fertility but is also linked to a higher risk of age-related diseases in women (e.g. osteoporosis, dementia). Intriguingly, earlier menopause is linked to shorter lifespan; however, the underlying molecular mechanisms of ovarian aging are not well understood. Recent evidence suggests the gut microbiota may influence ovarian health. In this study, we characterized ovarian aging associated microbial profiles in mice and investigated the effect of the gut microbiome from young and estropausal female mice on ovarian health through fecal microbiota transplantation. We demonstrate that the ovarian transcriptome can be broadly remodeled after heterochronic microbiota transplantation, with a reduction in inflammation-related gene expression and trends consistent with transcriptional rejuvenation. Consistently, these mice exhibited enhanced ovarian health and increased fertility. Using metagenomics-based causal mediation analyses and serum untargeted metabolomics, we identified candidate microbial species and metabolites that may contribute to the observed effects of fecal microbiota transplantation. Our findings reveal a direct link between the gut microbiota and ovarian health.

Global burden of young-onset dementia, from 1990 to 2021: an age-period-cohort analysis from the global burden of disease study 2021

This study aims to assess the burden of young-onset dementia worldwide, regionally, and nationally during 1990-2021. Prevalence, incidence, mortality, and disability adjusted life years (DALYs) rates were used to estimate burden of the young-onset dementia. The average annual percentage was utilized to evaluate the trends during 1990-2021. Decomposition analysis was performed to explore driving factors behind changes. Age-period-cohort modeling was used to estimate local drift, age, period and cohort effects. Global age standardized prevalence and incidence of dementia among people under 65 years increased from 93.39 and 16.24 per 100,000 persons in 1990 to 96.09 and 17.16 per 100,000 persons in 2021; mortality increased from 0.89 per 100,000 population to 0.91 per 100,000 population; and age standardized DALYs increased from 45.60 per 100,000 persons to 46.78 per 100,000 persons. Countries with a high, high-middle, and middle SDI experienced an upward trend of prevalence and incidence, and the mortality and DALYs of young-onset dementia in countries with a low-middle and low sociodemographic index was a higher level. Smoking, high body-mass index and high fasting plasma glucose levels were main risk factors. Population growth was the largest factor for the increasing young-onset dementia in all regions. Globally, prevalence, incidence, and DALYs rate of young-onset dementia increased with age, period effects showing a decreasing risk and then an increasing risk. Cohort effects of prevalence and DALYs began to decline after the 1950s. Young-onset dementia presents a growing global health challenge in the age, period and cohort across SDI regions, countries.

Ovarian Aging: The Silent Catalyst of Age-Related Disorders in Female Body

Age-related diseases have emerged as a global concern as the population ages. Consequently, understanding the underlying causes of aging and exploring potential anti-aging interventions is imperative. In females, the ovaries serve as the principal organs responsible for ovulation and the production of female hormones. The aging ovaries are related to infertility, menopause, and associated menopausal syndromes, with menopause representing the culmination of ovarian aging. Current evidence indicates that ovarian aging may contribute to dysfunction across multiple organ systems, including, but not limited to, cognitive impairment, osteoporosis, and cardiovascular disease. Nevertheless, due to the widespread distribution of sex hormone receptors throughout the body, ovarian aging affects not only these specific organs but also influences a broader spectrum of age-related diseases in women. Despite this, the impact of ovarian aging on overall age-related diseases has been largely neglected. This review provides a thorough summary of the impact of ovarian aging on age-related diseases, encompassing the nervous, circulatory, locomotor, urinary, digestive, respiratory, and endocrine systems. Additionally, we have outlined prospective therapeutic approaches for addressing both ovarian aging and age-related diseases, with the aim of mitigating their impacts and preserving women's fertility, physical health, and psychological well-being.

Causal association of sex hormone-related traits with Alzheimer's disease: a multivariable and network Mendelian randomization analysis

Background

Although studies have demonstrated a correlation between sex hormone-related traits [such as sex hormone binding globulin (SHBG) and testosterone] and Alzheimer's Disease (AD), the link remains uncertain due to the intricacies of AD pathology. The study aimed to investigate the possible causal link between sex hormone-related traits and AD.

Methods

The authors collected data from extensive genome-wide association studies (GWASs) of European ancestry on sex hormone-related traits and AD. Univariate and multivariate Mendelian randomization (MR) analyses were conducted to explore the possible causal relationship between these traits and AD. We used inverse variance weighted (IVW) MR as the main analysis.

Results

The use of univariate MR-IVW revealed a possible causal relationship between SHBG [ORs (95% CI), 1.005 (1.001-1.009), p = 0.006], testosterone [ORs (95% CI), 0.994 (0.989-0.999), p = 0.013] and AD in female. There is no evidence of a causal association of SHBG [ORs (95% CI), 1.002 (0.999-1.005)), p = 0.237] and testosterone [ORs (95% CI), 1.000 (0.997-1.004), p = 0.810] with AD in males. Multivariate MR analysis revealed a possible direct causal connection between SHBG and testosterone in relation to females AD (SHBG-OR (95%CI), 1.005 (1.001-1.009, p = 0.023); testosterone-OR (95%CI), 0.995 (0.989-1.000, p = 0.049). Bidirectional MR analysis indicated that SHBG has a possible causal effect on testosterone (SHBG on testosterone-OR (95%CI), 1.064 (1.032-1.096), p = 0.0001). The results of the network MR analysis suggested that testosterone may act as a mediator in the causal pathway from SHBG to AD.

Conclusion

Our study using the MR methodology indicates that increase of SHBG level and decrease of testosterone level in females are positively linked to an increased risk of developing AD. Importantly, testosterone plays a mediating role in the causal pathway from SHBG to females AD.

Muscle-derived myostatin is a major endocrine driver of follicle-stimulating hormone synthesis

Myostatin is a paracrine myokine that regulates muscle mass in a variety of species, including humans. In this work, we report a functional role for myostatin as an endocrine hormone that directly promotes pituitary follicle-stimulating hormone (FSH) synthesis and thereby ovarian function in mice. Previously, this FSH-stimulating role was attributed to other members of the transforming growth factor-β family, the activins. Our results both challenge activin's eponymous role in FSH synthesis and establish an unexpected endocrine axis between skeletal muscle and the pituitary gland. Our data also suggest that efforts to antagonize myostatin to increase muscle mass may have unintended consequences on fertility.

Atlas of Fshr expression from novel reporter mice

The FSH-FSHR pathway has been considered an essential regulator in reproductive development and fertility. But there has been emerging evidence of FSHR expression in extragonadal organs. This poses new questions and long-term debates regarding the physiological role of the FSH-FSHR, and underscores the need for reliable, in vivo analysis of FSHR expression in animal models. However, conventional methods have proven insufficient for examining FSHR expression due to several limitations. To address this challenge, we developed Fshr-ZsGreen reporter mice under the control of Fshr endogenous promoter using CRISPR-Cas9. With this novel genetic tool, we provide a reliable readout of Fshr expression at single-cell resolution level in vivo and in real time. Reporter animals were also subjected to additional analyses,to define the accurate expression profile of FSHR in gonadal and extragonadal organs/tissues. Our compelling results not only demonstrated Fshr expression in intragonadal tissues but also, strikingly, unveiled notably increased expression in Leydig cells, osteoblast lineage cells, endothelial cells in vascular structures, and epithelial cells in bronchi of the lung and renal tubes. The genetic decoding of the widespread pattern of Fshr expression highlights its physiological relevance beyond reproduction and fertility, and opens new avenues for therapeutic options for age-related disorders of the bones, lungs, kidneys, and hearts, among other tissues. Exploiting the power of the Fshr knockin reporter animals, this report provides the first comprehensive genetic record of the spatial distribution of FSHR expression, correcting a long-term misconception about Fshr expression and offering prospects for extensive exploration of FSH-FSHR biology.

A Comprehensive Analysis of Sex-Biased Gene Expression in the Aging Human Retina Through a Combination of Single-Cell and Bulk RNA Sequencing

Purpose

Previous studies have reported divergent sexual responses to aging; however, specific variations in gene expression between aging males and females and their potential association with age-related retinal diseases remain unclear. This study collected data from public databases and developed a comprehensive comparison of retina between aging females and males.

Methods

Single-cell RNA (scRNA) and bulk RNA sequencing data of the aging retina from females and males in public databases were utilized for integrated analysis to investigate sex-biased expression in retina. Additionally, in vitro experiments were conducted on individuals with retinitis pigmentosa (RP) to validate the sex difference in degenerative retina.

Results

Bulk RNA analysis revealed sex-biased expression of specific genes in retina of aging individuals, with immune pathway-related genes exhibiting higher expression in females compared to males. The scRNA analysis demonstrated that sex-biased gene expression was cell-type specific in aging retina. Furthermore, susceptibility genes for age-related macular degeneration and RP exhibited variation across different cell types and sexes. Cell-to-cell communication unveiled an increased interaction associated with TGFB1, CCL7, and VEGFA in Müller glia, microglia, and astrocytes of female retina. Notably, we observed female-biased chemokine expression in microglia contributing to heightened susceptibility to immune inflammation in female retina. Finally, we confirmed a more pronounced inflammatory response during degeneration in female rd10 mouse retina compared to males.

Conclusions

This study provides a comprehensive comparison of retina between females and males in healthy aging human retina and highlights the significance of sex as an influential factor in retinal diseases.

Histopathological changes of nervous tissue in women over 60 years of age with Alzheimer's disease and their relationship with menopause

INTRODUCTION

Ageing is a natural and irreversible process that primarily manifests in older age, becoming more common after the age of 60. Currently, a significant increase has been observed in the elderly population, with forecasts indicating that this group will triple in size over the next 50 years. This phenomenon is evident in several countries, including Japan, Mexico, Brazil, and Colombia, where the growing population of older adults is accompanied by an increased risk of neurodegenerative diseases, such as Alzheimer's disease. Studies have shown differences in the onset and progression of the disease between men and women, highlighting menopause and hormonal factors as key determinants in women. An association has been identified between a lower exposure to endogenous oestrogens and a higher risk of dementia in women, linked to the action of the enzyme β-secretase (BACE1), which is involved in the formation of amyloid aggregates associated with Alzheimer's disease. These findings highlight the importance of thoroughly investigating and understanding the impact of ageing and related diseases on the current and future population.

OBJECTIVE

This study aims to describe the histopathological changes in nervous tissue in women over 60 years of age with Alzheimer's disease and their relationship to menopause.

METHODOLOGY

A comprehensive search was conducted in databases such as PubMed, ScienceDirect, Frontiers, Scopus, and Springer.

RESULTS

Two hundred thirteen articles were selected for review and 45 full articles were chosen.

CONCLUSIONS

Alzheimer's disease is characterised by a progressive loss of cognitive function due to brain lesions, including the accumulation of amyloid-beta plaques and neuronal apoptosis. Hormonal changes during menopause may contribute to the onset of the disease.

Revisiting the follicle-stimulation hormone receptor expression and function in human myometrium and adipose tissue

BACKGROUND

Extragonadal follicle-stimulating hormone receptor (FSHR) expression at low levels has been shown in several normal and tumor tissues, including myometrium and adipose tissue. FSH-FSHR signaling in the myometrium has been suggested to regulate uterine contractile activity and the timing of labor. In contrast, FSH-FSHR has been linked to the activation of brown/beige fat thermogenesis in adipose tissue. The issue of extragonadal FSHR expression and its functionality remains contentious within the scientific community, as contradictory findings necessitate further independent and critical analyses. Hereby, we re-investigated the FSHR expression and its functionality in normal non-pregnant (M-NP) and pregnant (N-P) human myometrium, as well as in human visceral (VAT) and subcutaneous (SCAT) adipose tissue (AT).

METHODS

FSHR expression at mRNA (real-time qPCR, RNAscope in situ hybridization) and protein (immunohistochemical staining) levels in adipose tissue, myometrium, and adipocytes were evaluated. Myometrium and adipocytes were treated with recombinant (rh)FSH to study its effects on functional pathways. Myometrium contractile activity was measured using a force transducer with digital output and the DASYLab software unit. Cyclic adenosine monophosphate (cAMP) production by myometrium explants and adipocytes was measured using a cAMP ELISA Kit. The activation of the AKT pathway in myometrium and adipocytes was analyzed by Western blot analysis.

RESULTS

Contrary to previous observations, we found no expression of FSHR at either mRNA or protein levels in M-NP, N-P, VAT, and SCAT. Treatment with recombinant human FSH (rhFSH) showed no effect on cAMP production or phosphorylation of AKT in M-NP, N-P, as well as in VAT and SCAT. rhFSH treatment did not influence contractile activity in M-NP, N-P.

CONCLUSIONS

These findings suggest that the FSHR signaling pathway does not regulate myometrial contractility during pregnancy. Additionally, the absence of FSHR expression in both VAT and SCAT implied that FSHR does not play a role in the functional signaling pathways in adipose tissues. In conclusion, our findings contradict earlier data on the involvement of FSH-FSHR signaling in regulating myometrial contractility near term, as well as in adipose tissue function.

Mediterranean diet related to 3-year incidence of cognitive decline: results from a cohort study in Chinese rural elders

OBJECTIVE

This study aims to examine the effect of the Mediterranean diet (MeDi) on cognitive decline among the Chinese elderly with a 3-year follow-up.

METHODS

This study is divided into two waves: wave-1 January 2019 to June 2019 (n = 2313); wave-2 January 2022 to March 2022 (n = 1648). MeDi scores were calculated from the Mediterranean Diet Adherence Screener (MEDAS), with the scoring of low compliance (0-6 points) and high compliance (7-14 points). The Mini-Mental State Examination (MMSE) was used to assess cognitive function. An MMSE score dropping ≥ 2 points from baseline was defined as cognitive decline. The relationships between MeDi score and cognitive decline were analyzed by linear regression models or Binary logistic regression.

RESULTS

During the 3-year follow-up, 23.8% of patients exhibited cognitive decline. The study revealed a significant difference in MMSE score changes between low and high MeDi adherence groups (p < 0.001). MeDi score was negatively correlated with cognitive deterioration (β = -0.020, p = 0.026). MeDi score was only negatively associated with cognitive decline in the female subgroup aged ≥65 years (β = -0.034, p = 0.033). The food beans (OR = 0.65, 95%CI:0.51, 0.84), fish (OR = 0.72, 95%CI:0.54, 0.97), and cooked vegetables (OR = 0.68, 95%CI:0.53, 0.84) were protective factors for cognitive decline.

CONCLUSIONS

This study suggests that greater adherence to the MeDi is linked to a reduced risk of cognitive decline in elderly people. However, this is found only in women who are 65 years old or older. It also found long-term adherence to beans, fish, and vegetables are more effective in improving cognitive function.

The relationship between male and female endogenous reproductive hormones levels and subjective cognitive decline score: A cross-sectional analysis of the Pingyin cohort study

OBJECTIVE

Reproductive hormones might impact disease course in cognitive decline. We examined the association between male and female endogenous reproductive hormones and subjective cognitive decline (SCD) score.

DESIGN, PATIENTS AND MEASUREMENTS

A cross-sectional study design was used with baseline data from the Pingyin cohort study, involving 1943 participants aged 45-70 years. Oestrogen (E2), testosterone, follicle stimulating hormone (FSH) and luteinizing hormone (LH) were measured in females and E2 and testosterone were measured in males. We categorised hormones into three levels of low, intermediate and high level. The 9-item subjective cognitive decline questionnaire (SCD-Q9) scores were collected to assess the symptoms of SCD. Multivariable logistic regression models were used to estimate odds ratios (ORs) and 95% confidence interval (CI) between categorised hormone levels and SCD status. Multivariable linear regression models were also used.

RESULTS

Overall, 1943 participants were involved and 1285 (66.1%) were female. The mean age at baseline was 59.1 (standard deviation 7.1) years. Women with high testosterone levels had a higher probability of having SCD compared with those with low testosterone levels (OR 1.43, 95% CI 1.01-2.05). Men with a high level of testosterone (0.59, 0.35-0.98) and high testosterone/E2 ratio (0.55, 0.33-0.90) were related to decreased chances of having SCD. Each one-unit increase of testosterone was linked to reduced SCD score in males [(β: -.029, 95% CI (-0.052, -0.007)].

CONCLUSION

There was sex-specific relationship between hormone levels and SCD abnormal. Those with higher testosterone levels in females may increase likelihood of experiencing SCD. Males with higher testosterone levels and higher testosterone/E2 ratio may be associated with reduced likelihood of SCD. The roles of endogenous reproductive hormone levels and their dynamic changes in cognitive function need further investigation.

Neuroendocrinology of bone

The past decade has witnessed significant advances in our understanding of skeletal homeostasis and the mechanisms that mediate the loss of bone in primary and secondary osteoporosis. Recent breakthroughs have primarily emerged from identifying disease-causing mutations and phenocopying human bone disease in rodents. Notably, using genetically-modified rodent models, disrupting the reciprocal relationship with tropic pituitary hormone and effector hormones, we have learned that pituitary hormones have independent roles in skeletal physiology, beyond their effects exerted through target endocrine glands. The rise of follicle-stimulating hormone (FSH) in the late perimenopause may account, at least in part, for the rapid bone loss when estrogen is normal, while low thyroid-stimulating hormone (TSH) levels may contribute to the bone loss in thyrotoxicosis. Admittedly speculative, suppressed levels of adrenocorticotropic hormone (ACTH) may directly exacerbate bone loss in the setting of glucocorticoid-induced osteoporosis. Furthermore, beyond their established roles in reproduction and lactation, oxytocin and prolactin may affect intergenerational calcium transfer and therefore fetal skeletal mineralization, whereas elevated vasopressin levels in chronic hyponatremic states may increase the risk of bone loss.. Here, we discuss the interaction of each pituitary hormone in relation to its role in bone physiology and pathophysiology.

Menopause and Alzheimer's disease susceptibility: Exploring the potential mechanisms

Alzheimer's Disease (AD), responsible for 62% of all dementia cases, is a progressive neurodegenerative condition that leads to cognitive dysfunction. The prevalence of AD is consistently higher in women suggesting they are disproportionately affected by this disease. Despite this, our understanding of this female AD vulnerability remains limited. Menopause has been identified as a potential contributing factor to AD in women, with earlier menopause onset associated with greater AD risk. However, the underlying mechanisms responsible for this increased risk are not fully understood. This review examines the potential role of menopause in the development of Alzheimer's Disease providing a mechanistic overview of the available literature from hormones to pathology. While literature is now emerging that indicates a role of hormonal shifts, gut dysbiosis, lipid dysregulation and inflammation, more research is needed to fully elucidate the mechanisms involved.

Tlr7 drives sex differences in age- and Alzheimer's disease-related demyelination

Alzheimer's disease (AD) and other age-related disorders associated with demyelination exhibit sex differences. In this work, we used single-nuclei transcriptomics to dissect the contributions of sex chromosomes and gonads in demyelination and AD. In a mouse model of demyelination, we identified the roles of sex chromosomes and gonads in modifying microglia and oligodendrocyte responses before and after myelin loss. In an AD-related mouse model expressing APOE4, XY sex chromosomes heightened interferon (IFN) response and tau-induced demyelination. The X-linked gene, Toll-like receptor 7 (Tlr7), regulated sex-specific IFN response to myelin. Deletion of Tlr7 dampened sex differences while protecting against demyelination. Administering TLR7 inhibitor mitigated tau-induced motor impairment and demyelination in male mice, indicating that Tlr7 plays a role in the male-biased type I Interferon IFN response in aging- and AD-related demyelination.

Research progress on FSH-FSHR signaling in the pathogenesis of non-reproductive diseases

Follicle-stimulating hormone (FSH), a glycoprotein hormone synthesized and secreted by the anterior pituitary gland, plays a critical role in reproductive development and regulation by binding to FSH receptor (FSHR). Beyond reproductive tissue, FSHRs have been identified in various non-reproductive tissues, indicating broader functions. FSH levels chronically rise during menopause and remain elevated in postmenopausal life. This increase in FSH level has been indicated to be associated with heightened risk of several non-reproductive diseases, including osteoporosis, hypercholesterolemia, type 2 diabetes mellitus, obesity, cardiovascular disease, Alzheimer's disease, and certain cancers. In this review, we will examine the role of FSH-FSHR signaling in the pathogenesis of these non-reproductive diseases and explore therapeutic strategies targeting FSH-FSHR signaling pathways.

Prolactin deficiency drives diabetes-associated cognitive dysfunction by inducing microglia-mediated synaptic loss

BACKGROUND

Diabetes-associated cognitive dysfunction, characterized by hippocampal synaptic loss as an early pathological feature, seriously threatens patients' quality of life. Synapses are dynamic structures, and hormones play important roles in modulating the formation and elimination of synapses. The pituitary, the master gland of the body, releases several hormones with multiple roles in hippocampal synaptic regulation. In this study, we aimed to explore the relationship between pituitary hormones and cognitive decline in diabetes.

METHODS

A total of 744 patients with type 2 diabetes (T2DM) (445 men and 299 postmenopausal women) who underwent serum pituitary hormone level assessments, comprehensive cognitive evaluations and MRI scans were enrolled. Dynamic diet interventions were applied in both chow diet-fed mice and high-fat diet (HFD)-fed diabetic mice. The cognitive performance and hippocampal pathology of prolactin (PRL)-knockout mice, neuronal prolactin receptor (PRLR)-specific knockout mice and microglial PRLR-specific knockout mice were assessed. Microglial PRLR-specific knockout mice were fed an HFD to model diabetes. Diabetic mice received an intracerebroventricular infusion of recombinant PRL protein or vehicle.

RESULTS

This clinical study revealed that decreased PRL levels were associated with cognitive impairment and hippocampal damage in T2DM patients. In diabetic mice, PRL levels diminished before hippocampal synaptic loss and cognitive decline occurred. PRL loss could directly cause cognitive dysfunction and decreased hippocampal synaptic density. Knockout of PRLR in microglia, rather than neurons, induced hippocampal synaptic loss and cognitive impairment. Furthermore, blockade of PRL/PRLR signaling in microglia exacerbated abnormal microglial phagocytosis of synapses, further aggravating hippocampal synaptic loss and cognitive impairment in diabetic mice. Moreover, PRL infusion reduced microglia-mediated synaptic loss, thereby alleviating cognitive impairment in diabetic mice.

CONCLUSION

PRL is associated with cognitive dysfunction and hippocampal damage in T2DM patients. In diabetes, a decrease in PRL level drives hippocampal synaptic loss and cognitive impairment by increasing microglia-mediated synapse engulfment. Restoration of PRL levels ameliorates cognitive dysfunction and hippocampal synaptic loss in diabetic mice.

Stem cell transplantation extends the reproductive life span of naturally aging cynomolgus monkeys

The ovary is crucial for female reproduction and health, as it generates oocytes and secretes sex hormones. Transplantation of mesenchymal stem cells (MSCs) has been shown to alleviate pathological ovarian aging. However, it is unclear whether MSCs could benefit the naturally aging ovary. In this study, we first examined the dynamics of ovarian reserve of Chinese women during perimenopause. Using a naturally aging cynomolgus monkey (Macaca fascicularis) model, we found that transplanting human embryonic stem cells-derived MSC-like cells, which we called M cells, into the aging ovaries significantly decreased ovarian fibrosis and DNA damage, enhanced secretion of sex hormones and improved fertility. Encouragingly, a healthy baby monkey was born after M-cell transplantation. Moreover, single-cell RNA sequencing analysis and in vitro functional validation suggested that apoptosis, oxidative damage, inflammation, and fibrosis were mitigated in granulosa cells and stromal cells following M-cell transplantation. Altogether, these findings demonstrate the beneficial effects of M-cell transplantation on aging ovaries and expand our understanding of the molecular mechanisms underlying ovarian aging and stem cell-based alleviation of this process.

Cell non-autonomous signaling through the conserved C. elegans glycoprotein hormone receptor FSHR-1 regulates cholinergic neurotransmission

Modulation of neurotransmission is key for organismal responses to varying physiological contexts such as during infection, injury, or other stresses, as well as in learning and memory and for sensory adaptation. Roles for cell autonomous neuromodulatory mechanisms in these processes have been well described. The importance of cell non-autonomous pathways for inter-tissue signaling, such as gut-to-brain or glia-to-neuron, has emerged more recently, but the cellular mechanisms mediating such regulation remain comparatively unexplored. Glycoproteins and their G protein-coupled receptors (GPCRs) are well-established orchestrators of multi-tissue signaling events that govern diverse physiological processes through both cell-autonomous and cell non-autonomous regulation. Here, we show that follicle stimulating hormone receptor, FSHR-1, the sole Caenorhabditis elegans ortholog of mammalian glycoprotein hormone GPCRs, is important for cell non-autonomous modulation of synaptic transmission. Inhibition of fshr-1 expression reduces muscle contraction and leads to synaptic vesicle accumulation in cholinergic motor neurons. The neuromuscular and locomotor defects in fshr-1 loss-of-function mutants are associated with an underlying accumulation of synaptic vesicles, build-up of the synaptic vesicle priming factor UNC-10/RIM, and decreased synaptic vesicle release from cholinergic motor neurons. Restoration of FSHR-1 to the intestine is sufficient to restore neuromuscular activity and synaptic vesicle localization to fshr-1-deficient animals. Intestine-specific knockdown of FSHR-1 reduces neuromuscular function, indicating FSHR-1 is both necessary and sufficient in the intestine for its neuromuscular effects. Re-expression of FSHR-1 in other sites of endogenous expression, including glial cells and neurons, also restored some neuromuscular deficits, indicating potential cross-tissue regulation from these tissues as well. Genetic interaction studies provide evidence that downstream effectors gsa-1/GαS, acy-1/adenylyl cyclase and sphk-1/sphingosine kinase and glycoprotein hormone subunit orthologs, GPLA-1/GPA2 and GPLB-1/GPB5, are important for intestinal FSHR-1 modulation of the NMJ. Together, our results demonstrate that FSHR-1 modulation directs inter-tissue signaling systems, which promote synaptic vesicle release at neuromuscular synapses.

Spatial learning and memory impairment at the post-follicular depletion state is associated with reduced hippocampal glucose uptake

The menopausal transition is a complex neuroendocrine aging process affecting brain structure and metabolic function. Such changes are consistent with neurological sequelae noted following the menopausal transition, including cognitive deficits. Although studies in rodent models of the menopause revealed changes in learning and memory, little is known about the structural and metabolic changes in the brain regions serving the cognitive function in these models. The administration 4-vinylcyclohexene diepoxide (VCD) in laboratory animals results in follicular depletion, and thus, is a powerful translational tool that models the human menopause. In the studies presented here, we evaluated behavior, brain structure, and metabolism in young female rats administered with either VCD or vehicle for 15 days across the early, mid, and post-follicular depletion states at 1-, 2-, and 3-months post-final injection, respectively. Additionally, we evaluated the serum hormonal profile and ovarian follicles based on the estrous cycle pattern. Positron emission tomography (PET) was utilized to determine regional brain glucose metabolism in the hippocampus, medial prefrontal cortex, and striatum. Subsequently, the rats were euthanized for ex-vivo magnetic resonance imaging (MRI) to assess regional brain volumes. VCD-induced rats at the post-follicular depleted time points had diminished spatial learning and memory as well as reduced hippocampal glucose uptake. Additionally, VCD-induced rats at post-follicular depletion time points had marked reductions in estradiol, progesterone, and anti-mullerian hormone with an increase in follicle-stimulating hormone. These rats also exhibited fewer ovarian follicles, indicating that substantial ovarian function loss during post-follicular time points impairs the female rats' spatial learning/memory abilities and triggers the metabolic changes in the hippocampus.

High caloric intake improves neuronal metabolism and functional hyperemia in a rat model of early AD pathology

Introduction: While obesity has been linked to both increased and decreased rate of cognitive decline in Alzheimer's Disease (AD) patients, there is no consensus on the interaction between obesity and AD. Methods: The TgF344-AD rat model was used to investigate the effects of high carbohydrate, high fat (HCHF) diet on brain glucose metabolism and hemodynamics in the presence or absence of AD transgenes, in presymptomatic (6-month-old) vs. symptomatic (12-month-old) stages of AD progression using non-invasive neuroimaging. Results: In presymptomatic AD, HCHF exerted detrimental effects, attenuating both hippocampal glucose uptake and resting perfusion in both non-transgenic and TgAD cohorts, when compared to CHOW-fed cohorts. In contrast, HCHF consumption was beneficial in established AD, resolving the AD-progression associated attenuation in hippocampal glucose uptake and functional hyperemia. Discussion: Whereas HCHF was harmful to the presymptomatic AD brain, it ameliorated deficits in hippocampal metabolism and neurovascular coupling in symptomatic TgAD rats.

Follicle-stimulating hormone induces depression-like phenotype by affecting synaptic function

Depression is one of the most common affective disorders in people's life. Women are susceptibility to depression during puberty, peripartum and menopause transition, when they are suffering from sex hormone fluctuation. A lot of studies have demonstrated the neuroprotective effect of estrogen on depression in women, however, the effect of FSH on depression is unclear. In this study, we investigated the role of FSH on depression in mice. Our study demonstrated that FSH induced depression-like behaviors in mice in a dose-dependent manner. This induction was associated with elevated levels of pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α in both serum and hippocampal tissues. Additionally, FSH treatment resulted in impaired synaptic plasticity and a reduction in the expression of key synaptic proteins. It is noteworthy that the depression-like behaviors, inflammatory cytokines expression and synaptic plasticity impairment induced by FSH could be alleviated by knocking down the expression of FSH receptor (FSHR) in the hippocampus of the mice. Therefore, our findings reveal that FSH may play an important role in the pathogenesis of depression and targeting FSH may be a potential therapeutic strategy for depression during hormone fluctuation in women.

Higher FSH Level Is Associated With Increased Risk Of Incident Hip Fracture In Older Adults, Independent Of Sex Hormones

CONTEXT

Higher levels of FSH are associated with bone loss among women during the perimenopausal transition and among older men, independent of estradiol and testosterone levels, but whether higher FSH is an independent fracture risk factor is unknown.

OBJECTIVE

Determine whether baseline FSH level predicts subsequent hip fracture in older adults.

SETTING, DESIGN, PARTICIPANTS

Using a case-cohort design, we randomly sampled 295 participants stratified by sex from the Age, Gene/Environment Susceptibility (AGES)-Reykjavik cohort, including 25 participants with incident hip fracture within 10 years after baseline. We sampled an additional 230 sex-stratified participants with incident hip fracture. Serum FSH and sex hormone levels were measured at baseline. Robust weighted Cox proportional hazards models were used to determine the relationship between FSH and hip fracture risk.

MAIN OUTCOME

Incident hip fracture.

RESULTS

As no interaction was identified between FSH and sex for the relationship with fracture, men and women were pooled for analysis. Higher levels of FSH were associated with a significantly increased risk of incident hip fracture in models adjusted for age and sex [hazard ratio (HR) 1.24 (95% CI 1.04-1.48, p=0.02)] and after further adjustment for estradiol, testosterone, and sex hormone binding globulin levels [HR 1.20 (95% CI 1.01-1.44, p=0.04) per sex-specific SD increase in FSH level].

CONCLUSIONS

Higher FSH is associated with increased risk of subsequent hip fracture. Our findings support a growing body of evidence for direct pleiotropic effects of FSH on bone, and for a role for FSH in aging and disability independent of sex hormone levels.

Association of RDoC dimensions with post-mortem brain transcriptional profiles in Alzheimer's Disease

INTRODUCTION

Neuropsychiatric symptoms are common in people with Alzheimer's disease (AD) across all severity stages. Their heterogeneous presentation and variable temporal association with cognitive decline suggest shared and distinct biological mechanisms. We hypothesized that specific patterns of gene expression associate with distinct NIMH Research Domain Criteria (RDoC) domains in AD.

METHODS

Post-mortem bulk RNAseq on the insula and anterior cingulate cortex from 60 brain donors representing the spectrum of canonical AD neuropathology combined with natural language processing approaches based on the RDoC Clinical Domains.

RESULTS

Distinct sets of >100 genes (p FDR <0.05) were specifically associated with at least one clinical domain (Cognitive, Social, Negative, Positive, Arousal). In addition, dysregulation of immune response pathways was shared across domains and brain regions.

DISCUSSION

Our findings provide evidence for distinct transcriptional profiles associated with RDoC domains suggesting that each dimension is characterized by specific sets of genes providing insight into the underlying mechanisms.

Genetic and clinical correlates of two neuroanatomical AI dimensions in the Alzheimer's disease continuum

Alzheimer's disease (AD) is associated with heterogeneous atrophy patterns. We employed a semi-supervised representation learning technique known as Surreal-GAN, through which we identified two latent dimensional representations of brain atrophy in symptomatic mild cognitive impairment (MCI) and AD patients: the "diffuse-AD" (R1) dimension shows widespread brain atrophy, and the "MTL-AD" (R2) dimension displays focal medial temporal lobe (MTL) atrophy. Critically, only R2 was associated with widely known sporadic AD genetic risk factors (e.g., APOE ε4) in MCI and AD patients at baseline. We then independently detected the presence of the two dimensions in the early stages by deploying the trained model in the general population and two cognitively unimpaired cohorts of asymptomatic participants. In the general population, genome-wide association studies found 77 genes unrelated to APOE differentially associated with R1 and R2. Functional analyses revealed that these genes were overrepresented in differentially expressed gene sets in organs beyond the brain (R1 and R2), including the heart (R1) and the pituitary gland, muscle, and kidney (R2). These genes were enriched in biological pathways implicated in dendritic cells (R2), macrophage functions (R1), and cancer (R1 and R2). Several of them were "druggable genes" for cancer (R1), inflammation (R1), cardiovascular diseases (R1), and diseases of the nervous system (R2). The longitudinal progression showed that APOE ε4, amyloid, and tau were associated with R2 at early asymptomatic stages, but this longitudinal association occurs only at late symptomatic stages in R1. Our findings deepen our understanding of the multifaceted pathogenesis of AD beyond the brain. In early asymptomatic stages, the two dimensions are associated with diverse pathological mechanisms, including cardiovascular diseases, inflammation, and hormonal dysfunction-driven by genes different from APOE-which may collectively contribute to the early pathogenesis of AD. All results are publicly available at https://labs-laboratory.com/medicine/ .

Mind Gaps and Bone Snaps: Exploring the Connection Between Alzheimer's Disease and Osteoporosis

PURPOSE OF REVIEW

This comprehensive review discusses the complex relationship between Alzheimer's disease (AD) and osteoporosis, two conditions that are prevalent in the aging population and result in adverse complications on quality of life. The purpose of this review is to succinctly elucidate the many commonalities between the two conditions, including shared pathways, inflammatory and oxidative mechanisms, and hormonal deficiencies.

RECENT FINDINGS

AD and osteoporosis share many aspects of their respective disease-defining pathophysiology. These commonalities include amyloid beta deposition, the Wnt/β-catenin signaling pathway, and estrogen deficiency. The shared mechanisms and risk factors associated with AD and osteoporosis result in a large percentage of patients that develop both diseases. Previous literature has established that the progression of AD increases the risk of sustaining a fracture. Recent findings demonstrate that the reverse may also be true, suggesting that a fracture early in the life course can predispose one to developing AD due to the activation of these shared mechanisms. The discovery of these commonalities further guides the development of novel therapeutics in which both conditions are targeted. This detailed review delves into the commonalities between AD and osteoporosis to uncover the shared players that bring these two seemingly unrelated conditions together. The discussion throughout this review ultimately posits that the occurrence of fractures and the mechanism behind fracture healing can predispose one to developing AD later on in life, similar to how AD patients are at an increased risk of developing fractures. By focusing on the shared mechanisms between AD and osteoporosis, one can better understand the conditions individually and as a unit, thus informing therapeutic approaches and further research. This review article is part of a series of multiple manuscripts designed to determine the utility of using artificial intelligence for writing scientific reviews.

Chloride intracellular channel 4 blockade improves cognition in mice with Alzheimer's disease: CLIC4 protein expression and tau protein hyperphosphorylation

Numerous academic literature suggests that amyloid-β (Aβ) deposition, tau protein phosphorylation, and irreversible neuronal death are the three major causes of AD. The chloride intracellular channel (CLIC) protein family not only regulates the polarisation of neurons, but also has important implications for neuronal survival. Chloride intracellular channel 4 (CLIC4) can be pathologically activated by cyclin-dependent kinase 5 (Cdk5), which causes a significant increase in the expression of CLIC4 and mediates neuronal apoptosis. CLIC4 knockdown inhibits H2O2-induced neuronal apoptosis; however, the relationship between CLIC4 and AD remains unknown. In the present study, we showed that CLIC4 expression was elevated in the hippocampus of AD mice; knockdown of hippocampal CLIC4 alleviated Aβ25-35-induced cognitive impairment in mice; overexpression of hippocampal CLIC4 accelerated Aβ deposition and tau protein hyperphosphorylation in young AD mice (APP/PS1 mice at three months of age). CLIC4 overexpressing mice had a longer escape latency compared to controls in behavioural testing (Morris water maze and T-maze tests). By Co-immunoprecipitation/mass spectrometry (Co-IP/MS) of HT22 cells to identify proteins that specifically bind to CLIC4, we found interactions with CCAAT enhancer binding protein (C/EBPβ); a critical pathway involved in the development of various neurodegenerative diseases. In addition, the knockdown of hippocampal CLIC4 alleviated AD-like pathology by inhibiting the C/EBPβ/AEP signaling pathway. These data suggest an essential role for high CLIC4 expression in the pathophysiology of AD and reveal that inhibition of CLIC4 expression may provide an opportunity for treatment.

Lost in translation: Inconvenient truths on the utility of mouse models in Alzheimer's disease research

The recent, controversial approval of antibody-based treatments for Alzheimer's disease (AD) is fueling a heated debate on the molecular determinants of this condition. The discussion should also incorporate a critical revision of the limitations of preclinical mouse models in advancing our understanding of AD. We critically discuss the limitations of animal models, stressing the need for careful consideration of how experiments are designed and results interpreted. We identify the shortcomings of AD models to recapitulate the complexity of the human disease. We dissect these issues at the quantitative, qualitative, temporal, and context-dependent levels. We argue that these models are based on the oversimplistic assumptions proposed by the amyloid cascade hypothesis (ACH) of AD and fail to account for the multifactorial nature of the condition. By shedding light on the constraints of current experimental tools, this review aims to foster the development and implementation of more clinically relevant tools. While we do not rule out a role for preclinical models, we call for alternative approaches to be explored and, most importantly, for a re-evaluation of the ACH.