The endocrine dyscrasia that accompanies menopause and andropause induces aberrant cell cycle signaling that triggers re-entry of post-mitotic neurons into the cell cycle, neurodysfunction, neurodegeneration and cognitive disease

The Aggravating Role of Failing Neuropeptide Networks in the Development of Sporadic Alzheimer's Disease

Alzheimer's disease imposes an increasing burden on aging Western societies. The disorder most frequently appears in its sporadic form, which can be caused by environmental and polygenic factors or monogenic conditions of incomplete penetrance. According to the authors, in the majority of cases, Alzheimer's disease represents an aggravated form of the natural aging of the central nervous system. It can be characterized by the decreased elimination of amyloid β1-42 and the concomitant accumulation of degradation-resistant amyloid plaques. In the present paper, the dysfunction of neuropeptide regulators, which contributes to the pathophysiologic acceleration of senile dementia, is reviewed. However, in the present review, exclusively those neuropeptides or neuropeptide families are scrutinized, and the authors' investigations into their physiologic and pathophysiologic activities have made significant contributions to the literature. Therefore, the pathophysiologic role of orexins, neuromedins, RFamides, corticotrope-releasing hormone family, growth hormone-releasing hormone, gonadotropin-releasing hormone, ghrelin, apelin, and natriuretic peptides are discussed in detail. Finally, the therapeutic potential of neuropeptide antagonists and agonists in the inhibition of disease progression is discussed here.

Antineoplastics for treating Alzheimer's disease and dementia: Evidence from preclinical and observational studies

As the world population ages, there will be an increasing need for effective therapies for aging-associated neurodegenerative disorders, which remain untreatable. Dementia due to Alzheimer's disease (AD) is one of the leading neurological diseases in the aging population. Current therapeutic approaches to treat this disorder are solely symptomatic, making the need for new molecular entities acting on the causes of the disease extremely urgent. One of the potential solutions is to use compounds that are already in the market. The structures have known pharmacokinetics, pharmacodynamics, toxicity profiles, and patient data available in several countries. Several drugs have been used successfully to treat diseases different from their original purposes, such as autoimmunity and peripheral inflammation. Herein, we divulge the repurposing of drugs in the area of neurodegenerative diseases, focusing on the therapeutic potential of antineoplastics to treat dementia due to AD and dementia. We briefly touch upon the shared pathological mechanism between AD and cancer and drug repurposing strategies, with a focus on artificial intelligence. Next, we bring out the current status of research on the development of drugs, provide supporting evidence from retrospective, clinical, and preclinical studies on antineoplastic use, and bring in new areas, such as repurposing drugs for the prion-like spreading of pathologies in treating AD.

Emerging Role of ABC Transporters in Glia Cells in Health and Diseases of the Central Nervous System

ATP-binding cassette (ABC) transporters play a crucial role for the efflux of a wide range of substrates across different cellular membranes. In the central nervous system (CNS), ABC transporters have recently gathered significant attention due to their pivotal involvement in brain physiology and neurodegenerative disorders, such as Alzheimer's disease (AD). Glial cells are fundamental for normal CNS function and engage with several ABC transporters in different ways. Here, we specifically highlight ABC transporters involved in the maintenance of brain homeostasis and their implications in its metabolic regulation. We also show new aspects related to ABC transporter function found in less recognized diseases, such as Huntington's disease (HD) and experimental autoimmune encephalomyelitis (EAE), as a model for multiple sclerosis (MS). Understanding both their impact on the physiological regulation of the CNS and their roles in brain diseases holds promise for uncovering new therapeutic options. Further investigations and preclinical studies are warranted to elucidate the complex interplay between glial ABC transporters and physiological brain functions, potentially leading to effective therapeutic interventions also for rare CNS disorders.

Molecular pathways in placental-fetal development and disruption

The first trimester of pregnancy ranks high in priority when minimizing harmful exposures, given the wide-ranging types of organogenesis occurring between 4- and 12-weeks' gestation. One way to quantify potential harm to the fetus in the first trimester is to measure a corollary effect on the placenta. Placental biomarkers are widely present in maternal circulation, cord blood, and placental tissue biopsied at birth or at the time of pregnancy termination. Here we evaluate ten diverse pathways involving molecules expressed in the first trimester human placenta based on their relevance to normal fetal development and to the hypothesis of placental-fetal endocrine disruption (perturbation in development that results in abnormal endocrine function in the offspring), namely: human chorionic gonadotropin (hCG), thyroid hormone regulation, peroxisome proliferator activated receptor protein gamma (PPARγ), leptin, transforming growth factor beta, epiregulin, growth differentiation factor 15, small nucleolar RNAs, serotonin, and vitamin D. Some of these are well-established as biomarkers of placental-fetal endocrine disruption, while others are not well studied and were selected based on discovery analyses of the placental transcriptome. A literature search on these biomarkers summarizes evidence of placenta-specific production and regulation of each biomarker, and their role in fetal reproductive tract, brain, and other specific domains of fetal development. In this review, we extend the theory of fetal programming to placental-fetal programming.

Endocrine Dyscrasia in the Etiology and Therapy of Alzheimer's Disease

The increase in the incidence of dementia over the last century correlates strongly with the increases in post-reproductive lifespan during this time. As post-reproductive lifespan continues to increase it is likely that the incidence of dementia will also increase unless therapies are developed to prevent, slow or cure dementia. A growing body of evidence implicates age-related endocrine dyscrasia and the length of time that the brain is subjected to this endocrine dyscrasia, as a key causal event leading to the cognitive decline associated with aging and Alzheimer's disease (AD), the major form of dementia in our society. In particular, the elevations in circulating gonadotropins, resulting from the loss of gonadal sex hormone production with menopause and andropause, appear central to the development of AD neuropathology and cognitive decline. This is supported by numerous cell biology, preclinical animal, and epidemiological studies, as well as human clinical studies where suppression of circulating luteinizing hormone and/or follicle-stimulating hormone with either gonadotropin-releasing hormone analogues, or via physiological hormone replacement therapy, has been demonstrated to halt or significantly slow cognitive decline in those with AD. This review provides an overview of past and present studies demonstrating the importance of hypothalamic-pituitary-gonadal hormone balance for normal cognitive functioning, and how targeting age-related endocrine dyscrasia with hormone rebalancing strategies provides an alternative treatment route for those with AD.

Long-COVID cognitive impairments and reproductive hormone deficits in men may stem from GnRH neuronal death

BACKGROUND

We have recently demonstrated a causal link between loss of gonadotropin-releasing hormone (GnRH), the master molecule regulating reproduction, and cognitive deficits during pathological aging, including Down syndrome and Alzheimer's disease. Olfactory and cognitive alterations, which persist in some COVID-19 patients, and long-term hypotestosteronaemia in SARS-CoV-2-infected men are also reminiscent of the consequences of deficient GnRH, suggesting that GnRH system neuroinvasion could underlie certain post-COVID symptoms and thus lead to accelerated or exacerbated cognitive decline.

METHODS

We explored the hormonal profile of COVID-19 patients and targets of SARS-CoV-2 infection in post-mortem patient brains and human fetal tissue.

FINDINGS

We found that persistent hypotestosteronaemia in some men could indeed be of hypothalamic origin, favouring post-COVID cognitive or neurological symptoms, and that changes in testosterone levels and body weight over time were inversely correlated. Infection of olfactory sensory neurons and multifunctional hypothalamic glia called tanycytes highlighted at least two viable neuroinvasion routes. Furthermore, GnRH neurons themselves were dying in all patient brains studied, dramatically reducing GnRH expression. Human fetal olfactory and vomeronasal epithelia, from which GnRH neurons arise, and fetal GnRH neurons also appeared susceptible to infection.

INTERPRETATION

Putative GnRH neuron and tanycyte dysfunction following SARS-CoV-2 neuroinvasion could be responsible for serious reproductive, metabolic, and mental health consequences in long-COVID and lead to an increased risk of neurodevelopmental and neurodegenerative pathologies over time in all age groups.

FUNDING

European Research Council (ERC) grant agreements No 810331, No 725149, No 804236, the European Union Horizon 2020 research and innovation program No 847941, the Fondation pour la Recherche Médicale (FRM) and the Agence Nationale de la Recherche en Santé (ANRS) No ECTZ200878 Long Covid 2021 ANRS0167 SIGNAL, Agence Nationale de la recherche (ANR) grant agreements No ANR-19-CE16-0021-02, No ANR-11-LABEX-0009, No. ANR-10-LABEX-0046, No. ANR-16-IDEX-0004, Inserm Cross-Cutting Scientific Program HuDeCA, the CHU Lille Bonus H, the UK Medical Research Council (MRC) and National Institute of Health and care Research (NIHR).

Alzheimer's Disease: Novel Targets and Investigational Drugs for Disease Modification

Novel agents addressing non-amyloid, non-tau targets in Alzheimer's Disease (AD) comprise 70% of the AD drug development pipeline of agents currently in clinical trials. Most of the target processes identified in the Common Alzheimer's Disease Research Ontology (CADRO) are represented by novel agents in trials. Inflammation and synaptic plasticity/neuroprotection are the CADRO categories with the largest number of novel candidate therapies. Within these categories, there are few overlapping targets among the test agents. Additional categories being evaluated include apolipoprotein E [Formula: see text] 4 (APOE4) effects, lipids and lipoprotein receptors, neurogenesis, oxidative stress, bioenergetics and metabolism, vascular factors, cell death, growth factors and hormones, circadian rhythm, and epigenetic regulators. We highlight current drugs being tested within these categories and their mechanisms. Trials will be informative regarding which targets can be modulated to produce a slowing of clinical decline. Possible therapeutic combinations of agents may be suggested by trial outcomes. Biomarkers are evolving in concert with new targets and novel agents, and biomarker outcomes offer a means of supporting disease modification by the putative treatment. Identification of novel targets and development of corresponding therapeutics offer an important means of advancing new treatments for AD.

MicroRNA networks linked with BRCA1/2, PTEN, and common genes for Alzheimer's disease and breast cancer share highly enriched pathways that may unravel targets for the AD/BC comorbidity treatment

MicroRNAs (miRNAs) are involved in the regulation of various cellular processes including pathological conditions. MiRNA networks have been extensively researched in age-related degenerative diseases, such as cancer, Alzheimer's disease (AD), and heart failure. Thus, miRNA has been studied from different approaches, in vivo, in vitro, and in silico including miRNA networks. Networks linking diverse biomedical entities unveil information not readily observable by other means. This work focuses on biological networks related to Breast cancer susceptibility 1 (BRCA1) in AD and breast cancer (BC). Using various bioinformatics approaches, we identified subnetworks common to AD and BC that suggest they are linked. According to our results, miR-107 was identified as a potentially good candidate for both AD and BC treatment (targeting BRCA1/2 and PTEN in both diseases), accompanied by miR-146a and miR-17. The analysis also confirmed the involvement of the miR-17-92 cluster, and miR-124-3p, and highlighted the importance of poorly researched miRNAs such as mir-6785 mir-6127, mir-6870, or miR-8485. After filtering the in silico analysis results, we found 49 miRNA molecules that modulate the expression of at least five genes common to both BC and AD. Those 49 miRNAs regulate the expression of 122 genes in AD and 93 genes in BC, from which 26 genes are common genes for AD and BC involved in neuron differentiation and genesis, cell differentiation and migration, regulation of cell cycle, and cancer development. Additionally, the highly enriched pathway was associated with diabetic complications, pointing out possible interplay among molecules underlying BC, AD, and diabetes pathology.

The roles of GnRH in the human central nervous system

It is widely known that GnRH plays a role in facilitating reproductive function via the HPG axis, and this was once believed to be its only function. However, over the last several decades important neuromodulatory roles of GnRH in multiple brain functions have been elucidated. Multiple GnRH isoforms and receptors have been detected outside the HPG-axis across different species. In this review, we focus on the human CNS where GnRH I and II isoforms and a functional GnRH I receptor have been isolated. We first describe the traditional understanding of GnRH within the hypothalamus and the pituitary and current clinical use of GnRH analogues. We then review the location and function of GnRH-producing neurons and receptors located outside the HPG axis. We next review the GnRH I and II neuron location and quantity and GnRH I receptor gene expression throughout the human brain, using the Allen Brain Map Atlas. This analysis demonstrates a wide expression of GnRH throughout the brain, including prominent expression in the basal forebrain and cerebellum. Lastly, we examine the potential role of GnRH in aging and inflammation and its therapeutic potential for neurodegenerative disease and spinal cord lesions.

From Menopause to Neurodegeneration-Molecular Basis and Potential Therapy

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

Rationale, study design and implementation of the LUCINDA Trial: Leuprolide plus Cholinesterase Inhibition to reduce Neurologic Decline in Alzheimer's

The LUCINDA Trial (Leuprolide plus Cholinesterase Inhibition to reduce Neurologic Decline in Alzheimer's) is a 52 week, randomized, placebo-controlled trial of leuprolide acetate (Eligard) in women with Alzheimer's disease (AD). Leuprolide acetate is a gonadotropin analogue commonly used for hormone-sensitive conditions such as prostate cancer and endometriosis. This repurposed drug demonstrated efficacy in a previous Phase II clinical trial in those women with AD who also received a stable dose of the acetylcholinesterase inhibitor donepezil (Bowen et al., 2015). Basic biological, epidemiological and clinical trial data suggest leuprolide acetate mediates improvement and stabilization of neuropathology and cognitive performance via the modulation of gonadotropin and/or gonadotropin-releasing hormone signaling. LUCINDA will enroll 150 women with mild-moderate AD who are receiving a stable dose of donepezil from three study sites in the United States. Cognition and function are the primary outcome measures as assessed by the Alzheimer's Disease Assessment Scale-Cognitive Subscale. Blood and MRI biomarkers are also measured to assess hormonal, inflammatory and AD biomarker changes. We present the protocol for LUCINDA and discuss trial innovations and challenges including changes necessitated by the covid-19 pandemic and study drug procurement issues.

Hypogonadism induced by surgical stress and brain trauma is reversed by human chorionic gonadotropin in male rats: A potential therapy for surgical and TBI-induced hypogonadism?

INTRODUCTION

Hypogonadotropic hypogonadism (HH) is an almost universal, yet underappreciated, endocrinological complication of traumatic brain injury (TBI). The goal of this study was to determine whether the developmental hormone human chorionic gonadotropin (hCG) treatment could reverse HH induced by a TBI.

METHODS

Plasma samples were collected at post-surgery/post-injury (PSD/PID) days -10, 1, 11, 19 and 29 from male Sprague-Dawley rats (5- to 6-month-old) that had undergone a Sham surgery (craniectomy alone) or CCI injury (craniectomy + bilateral moderate-to-severe CCI injury) and treatment with saline or hCG (400 IU/kg; i.m.) every other day.

RESULTS

Both Sham and CCI injury significantly decreased circulating testosterone (T), 11-deoxycorticosterone (11-DOC) and corticosterone concentrations to a similar extent (79.1% vs. 80.0%; 46.6% vs. 48.4%; 56.2% vs. 32.5%; respectively) by PSD/PID 1. hCG treatment  returned circulating T to baseline concentrations by PSD/PID 1 (8.9 ± 1.5 ng/ml and 8.3 ± 1.9 ng/ml; respectively) and was maintained through PSD/PID 29. hCG treatment significantly, but transiently, increased circulating progesterone (P4) ~3-fold (30.2 ± 10.5 ng/ml and 24.2 ± 5.8 ng/ml) above that of baseline concentrations on PSD 1 and PID 1, respectively. hCG treatment did not reverse hypoadrenalism following either procedure.

CONCLUSIONS

Together, these data indicate that (1) craniectomy is sufficient to induce persistent hypogonadism and hypoadrenalism, (2) hCG can reverse hypogonadism induced by a craniectomy or craniectomy +CCI injury, suggesting that (3) craniectomy and CCI injury induce a persistent hypogonadism by decreasing hypothalamic and/or pituitary function rather than testicular function in male rats. The potential role of hCG as a cheap, safe and readily available treatment for reversing surgery or TBI-induced hypogonadism is discussed.

Cell Cycle Re-entry in the Nervous System: From Polyploidy to Neurodegeneration

Terminally differentiated cells of the nervous system have long been considered to be in a stable non-cycling state and are often considered to be permanently in G0. Exit from the cell cycle during development is often coincident with the differentiation of neurons, and is critical for neuronal function. But what happens in long lived postmitotic tissues that accumulate cell damage or suffer cell loss during aging? In other contexts, cells that are normally non-dividing or postmitotic can or re-enter the cell cycle and begin replicating their DNA to facilitate cellular growth in response to cell loss. This leads to a state called polyploidy, where cells contain multiple copies of the genome. A growing body of literature from several vertebrate and invertebrate model organisms has shown that polyploidy in the nervous system may be more common than previously appreciated and occurs under normal physiological conditions. Moreover, it has been found that neuronal polyploidization can play a protective role when cells are challenged with DNA damage or oxidative stress. By contrast, work over the last two and a half decades has discovered a link between cell-cycle reentry in neurons and several neurodegenerative conditions. In this context, neuronal cell cycle re-entry is widely considered to be aberrant and deleterious to neuronal health. In this review, we highlight historical and emerging reports of polyploidy in the nervous systems of various vertebrate and invertebrate organisms. We discuss the potential functions of polyploidization in the nervous system, particularly in the context of long-lived cells and age-associated polyploidization. Finally, we attempt to reconcile the seemingly disparate associations of neuronal polyploidy with both neurodegeneration and neuroprotection.

Chronic modafinil therapy ameliorates depressive-like behavior, spatial memory and hippocampal plasticity impairments, and sleep-wake changes in a surgical mouse model of menopause

Depression, cognitive deficits, and sleep disturbances are common and often severe in menopausal women. Hormone replacement cannot effectively alleviate these symptoms and sometimes elicits life-threatening adverse reactions. Exploring effective therapies to target psychological problems is urgently needed. In this work, we developed a mouse model of menopause by bilateral ovariectomies (OVXs) and investigated whether menopausal mental symptoms can be ameliorated by psychostimulant modafinil (MOD) as well as explored the underlying mechanisms. At ~3 weeks after OVXs, mice got daily intraperitoneal administrations of MOD at the beginning of the active phase. Several behavioral tests and electroencephalogram (EEG) recordings were conducted. Electrophysiological and immunohistochemical experiments were carried out to evaluate the synaptic plasticity and neurogenesis, respectively. We found that chronic MOD administration in OVX mice significantly decreased immobility time. The spatial memory performance of OVX mice improved significantly in response to MOD administration in the Morris water-maze test. The OVX mice were characterized by an attenuation of hippocampal synaptic transmission and synaptic long-term potentiation and had fewer 5-ethynyl-2'-deoxyuridine-labeled cells in the dentate gyrus, which were restored after MOD administration. Antagonists of dopamine D₁ and D₂ receptors and GABA_A receptor agonists were involved in MOD-exerted anti-depressant actions and augments of hippocampal neurogenesis in OVX mice. Moreover, night-dosed MOD therapy significantly promoted the night-time delta-band EEG power during wakefulness and the day-time rapid eye movement sleep amount, which were significantly reduced by OVXs. Collectively, these findings suggest that MOD is a promising therapeutic candidate for menopausal women.

Development of Classification Models for the Prediction of Alzheimer's Disease Utilizing Circulating Sex Hormone Ratios

BACKGROUND

While sex hormones are essential for normal cognitive health, those individuals with greater endocrine dyscrasia around menopause and with andropause are more likely to develop cognitive loss and Alzheimer's disease (AD).

OBJECTIVE

To assess whether circulating sex hormones may provide an etiologically significant, surrogate biomarker, for cognitive decline.

METHODS

Plasma (n = 152) and serum (n = 107) samples from age- and gender-matched AD and control subjects from the Wisconsin Alzheimer's Disease Research Center (ADRC) were analyzed for 11 steroids and follicle-stimulating hormone. Logistic regression (LR), correlation analyses, and recursive partitioning (RP) were used to examine the interactions of hormones and hormone ratios and their association with AD. Models generated were then tested on an additional 43 ADRC samples.

RESULTS

The wide variation and substantial overlap in the concentrations of all circulating sex steroids across control and AD groups precluded their use for predicting AD. Classification tree analyses (RP) revealed interactions among single hormones and hormone ratios that associated with AD status, the most predictive including only the hormone ratios identified by LR. The strongest associations were observed between cortisol, cortisone, and androstenedione with AD, with contributions from progesterone and 17β-estradiol. Utilizing this model, we correctly predicted 81% of AD test cases and 64% of control test cases.

CONCLUSION

We have developed a diagnostic model for AD, the Wisconsin Hormone Algorithm Test for Cognition (WHAT-Cog), that utilizes classification tree analyses of hormone ratios. Further refinement of this technology could provide a quick and cheap diagnostic method for screening those with AD.

Testosterone, sex steroids, and aging in neurodegenerative disease after acquired brain injury: a commentary

PRIMARY OBJECTIVE

Traumatic brain injury (TBI) is associated with higher incidence of neurodegenerative disease and the effects of aging appear more pronounced after TBI. This paper examines the potential interaction of aging, TBI, and change in male testosterone production.

METHODS AND PROCEDURES

An abbreviated review of literature documenting hypogonadism after TBI is provided. Potential mechanisms of endocrine dysgrasia associated with aging are reviewed as they relate and interact with endocrine change after TBI in males. These factors align to suggest the need for development of surveillance guidelines for male individuals living with TBI.

OUTCOMES AND RESULTS

The neuroprotectant, neuroactivation, growth, and cell therapy characteristics of testosterone in the central nervous system are considerable. Age-related decrements in testosterone production may be accelerated after TBI.

CONCLUSIONS

Testosterone deficiency in male individuals after TBI can be present after TBI or can develop during aging. Age-related decreases in testosterone production after TBI may act to amplify endocrine dysfunction after TBI. Ongoing clinical surveillance for testosterone deficiency associated with both TBI and aging may be reasonable.

The beneficial effects of physical exercise in the brain and related pathophysiological mechanisms in neurodegenerative diseases

Growing evidence has shown the beneficial influence of exercise on humans. Apart from classic cardioprotection, numerous studies have demonstrated that different exercise regimes provide a substantial improvement in various brain functions. Although the underlying mechanism is yet to be determined, emerging evidence for neuroprotection has been established in both humans and experimental animals, with most of the valuable findings in the field of mental health, neurodegenerative diseases, and acquired brain injuries. This review will discuss the recent findings of how exercise could ameliorate brain function in neuropathological states, demonstrated by either clinical or laboratory animal studies. Simultaneously, state-of-the-art molecular mechanisms underlying the exercise-induced neuroprotective effects and comparison between different types of exercise will be discussed in detail. A majority of reports show that physical exercise is associated with enhanced cognition throughout different populations and remains as a fascinating area in scientific research because of its universal protective effects in different brain domain functions. This article is to review what we know about how physical exercise modulates the pathophysiological mechanisms of neurodegeneration.

Paeoniflorin inhibits tributyltin chloride-induced apoptosis in hypothalamic neurons via inhibition of MKK4-JNK signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Paeoniflorin (PF) exerts a significant protective effect against neurotoxicity and mitochondrial damage in neurons. However, the mechanisms underlying PF-mediated rescue remain elusive. Therefore, we endeavored to further research the molecular mechanisms underlying PF-mediated inhibition of tributyltin chloride (TBTC)-induced apoptosis of neurons.

AIM OF THE STUDY

To investigate the influence and possible mechanism of action of PF in TBTC-induced neurodegenerative disease.

MATERIALS AND METHODS

First, primary hypothalamic neurons were treated with tributyltin chloride (150 μg/L) and PF (25, 50, and 100 μM). 17β-estradiol (1 nM) was used as a positive control. Subsequently, CCK-8 assay was performed. The level of apoptosis was examined by flow cytometry and the function of mitochondria was reflected by MMP levels. The mRNA expression levels of B-cell lymphoma-2 (Bcl-2), together with Bax, were examined using qRT-PCR. The protein levels of mitogen-activated protein kinase kinase 4 (MKK4), c-Jun N-terminal kinase (JNK), Bcl-2, Bax, and Caspase-3 were examined using western blotting. Finally, pretreatment with JNK agonist, anisomycin, was done to observe the change in expressions of MKK4 and JNK.

RESULTS

Paeoniflorin treatment reduced TBTC-induced damage and neuron loss in a dose-dependent manner. Decrease in mitogen-activated protein kinase (MAPK) as well as JNK levels were reversed by treatment with paeoniflorin via inhibition of JNK activation. Furthermore, ratio of levels of Bcl-2/Bax increased while the activation of caspase-3 was suppressed. In addition, pretreatment with JNK agonist, anisomycin effectively suppressed TBTC-induced cytotoxicity in hypothalamic neuron.

CONCLUSIONS

PF can potentially be used to prevent and/or treat neurodegenerative diseases and neural injury by inhibiting MKK4-JNK signaling pathway.

Region- and Cell-specific Aneuploidy in Brain Aging and Neurodegeneration

Variations in genomic DNA content, or aneuploidy, are a well-recognized feature of normal human brain development. Whether changes in the levels of aneuploidy are a factor in Alzheimer's disease (AD) is less clear, as the data reported to date vary substantially in the levels of aneuploidy detected (0.7-11.5%), possibly due to methodological limitations, but also influenced by individual, regional and cellular heterogeneity as well as variations in cell subtypes. These issues have not been adequately addressed to date. While it is known that the DNA damage response increases with age, the limited human studies investigating aneuploidy in normal aging also show variable results, potentially due to susceptibility to age-related neurodegenerative processes. Neuronal aneuploidy has recently been reported in multiple brain regions in Lewy body disease, but similar genomic changes are not a feature of all synucleinopathies and aneuploidy does not appear to be related to alpha-synuclein aggregation. Rather, aneuploidy was associated with Alzheimer's pathology in the hippocampus and anterior cingulate cortex and neuronal degeneration in the substantia nigra. The association between Alzheimer's pathology and aneuploidy in regions with limited neurodegeneration is supported by a growing body of in vitro and in vivo data on aneuploidy and beta-amyloid and tau abnormalities. Large-scale studies using high-resolution techniques alongside other sensitive and specific methodologies are now required to assess the true extent of cell- and region-specific aneuploidy in aging and neurodegeneration, and to determine any associations with pathologies.

Role of oxidative stress and DNA hydroxymethylation in the neurotoxicity of fine particulate matter

Epidemiological studies have implicated fine particulate matter (PM_2.5) as a risk factor for neurodegenerative diseases and neurodevelopmental disorders. However, the underlying molecular mechanisms and the influences of different components remain largely elusive. Here, we extended our previous work to investigate the role of oxidative stress and DNA hydroxymethylation in neuronal pathology of PM_2.5. We found PM_2.5 and its extracts (water-soluble extracts, organic extracts and carbon core component) differentially caused cell cycle arrest, cell apoptosis and the cell proliferation inhibition in neuronal cells. These effects were mechanistically related to each other and oxidative stress, suggesting PM_2.5 and toxic compounds adsorbed on the particles may cause different types of brain damages. In addition, PM_2.5 and its organic extracts increased global DNA hydroxymethylation and gene-specific DNA hydroxymethylation of neuronal genes, and subsequently interfered with their mRNA expression. The impairments in neuronal progression characterized with decreased length of neurite and reduced mRNA expression of neuronal markers and synaptic markers. The blocking effects of antioxidants demonstrated the involvement of oxidative stress-mediated hydroxymethylation abnormalities in PM_2.5-induced defects in neurite outgrowth and synapse formation. Our results first revealed the role of oxidative stress-mediated abnormal DNA hydroxymethylation in neuronal impairments of PM_2.5, and thoroughly evaluated the neurocytotoxicity of different components.

Conjugated Linoleic Acid Administration Induces Amnesia in Male Sprague Dawley Rats and Exacerbates Recovery from Functional Deficits Induced by a Controlled Cortical Impact Injury

Long-chain polyunsaturated fatty acids like conjugated linoleic acids (CLA) are required for normal neural development and cognitive function and have been ascribed various beneficial functions. Recently, oral CLA also has been shown to increase testosterone (T) biosynthesis, which is known to diminish traumatic brain injury (TBI)-induced neuropathology and reduce deficits induced by stroke in adult rats. To test the impact of CLA on cognitive recovery following a TBI, 5-6 month old male Sprague Dawley rats received a focal injury (craniectomy + controlled cortical impact (CCI; n = 17)) or Sham injury (craniectomy alone; n = 12) and were injected with 25 mg/kg body weight of Clarinol® G-80 (80% CLA in safflower oil; n = 16) or saline (n = 13) every 48 h for 4 weeks. Sham surgery decreased baseline plasma progesterone (P4) by 64.2% (from 9.5 ± 3.4 ng/mL to 3.4 ± 0.5 ng/mL; p = 0.068), T by 74.6% (from 5.9 ± 1.2 ng/mL to 1.5 ± 0.3 ng/mL; p < 0.05), 11-deoxycorticosterone (11-DOC) by 37.5% (from 289.3 ± 42.0 ng/mL to 180.7 ± 3.3 ng/mL), and corticosterone by 50.8% (from 195.1 ± 22.4 ng/mL to 95.9 ± 2.2 ng/mL), by post-surgery day 1. CCI injury induced similar declines in P4, T, 11-DOC and corticosterone (58.9%, 74.6%, 39.4% and 24.6%, respectively) by post-surgery day 1. These results suggest that both Sham surgery and CCI injury induce hypogonadism and hypoadrenalism in adult male rats. CLA treatment did not reverse hypogonadism in Sham (P4: 2.5 ± 1.0 ng/mL; T: 0.9 ± 0.2 ng/mL) or CCI-injured (P4: 2.2 ± 0.9 ng/mL; T: 1.0 ± 0.2 ng/mL, p > 0.05) animals by post-injury day 29, but rapidly reversed by post-injury day 1 the hypoadrenalism in Sham (11-DOC: 372.6 ± 36.6 ng/mL; corticosterone: 202.6 ± 15.6 ng/mL) and CCI-injured (11-DOC: 384.2 ± 101.3 ng/mL; corticosterone: 234.6 ± 43.8 ng/mL) animals. In Sham surgery animals, CLA did not alter body weight, but did markedly increase latency to find the hidden Morris Water Maze platform (40.3 ± 13.0 s) compared to saline treated Sham animals (8.8 ± 1.7 s). In CCI injured animals, CLA did not alter CCI-induced body weight loss, CCI-induced cystic infarct size, or deficits in rotarod performance. However, like Sham animals, CLA injections exacerbated the latency of CCI-injured rats to find the hidden MWM platform (66.8 ± 10.6 s) compared to CCI-injured rats treated with saline (30.7 ± 5.5 s, p < 0.05). These results indicate that chronic treatment of CLA at a dose of 25 mg/kg body weight in adult male rats over 1-month 1) does not reverse craniectomy- and craniectomy + CCI-induced hypogonadism, but does reverse craniectomy- and craniectomy + CCI-induced hypoadrenalism, 2) is detrimental to medium- and long-term spatial learning and memory in craniectomized uninjured rats, 3) limits cognitive recovery following a moderate-severe CCI injury, and 4) does not alter body weight.

The spatiotemporal hormonal orchestration of human folliculogenesis, early embryogenesis and blastocyst implantation

The early reproductive events starting with folliculogenesis and ending with blastocyst implantation into the uterine endometrium are regulated by a complex interplay among endocrine, paracrine and autocrine factors. This review examines the spatiotemporal integration of these maternal and embryonic signals that are required for successful reproduction. In coordination with hypothalamic-pituitary-gonadal (HPG) hormones, an intraovarian HPG-like axis regulates folliculogenesis, follicular quiescence, ovulation, follicular atresia, and corpus luteal functions. Upon conception and passage of the zygote through the fallopian tube, the contribution of maternal hormones in the form of paracrine secretions from the endosalpinx to embryonic development declines, with autocrine and paracrine signaling becoming increasingly important as instructional signals for the differentiation of the early zygote/morula into a blastocyst. These maternal and embryonic signals include activin and gonadotropin-releasing hormone 1 (GnRH1) that are crucial for the synthesis and secretion of the 'pregnancy' hormone human chorionic gonadotropin (hCG). hCG in turn signals pre-implantation embryonic cell division and sex steroid production required for stem cell differentiation, and subsequent blastulation, gastrulation, cavitation and blastocyst formation. Upon reaching the uterus, blastocyst hatching occurs under the influence of decreased activin signaling, while the attachment and invasion of the trophoblast into the endometrium appears to be driven by a decrease in activin signaling, and by increased GnRH1 and hCG signaling that allows for tissue remodeling and the controlled invasion of the blastocyst into the uterine endometrium. This review demonstrates the importance of integrative endocrine, paracrine, and autocrine signaling for successful human reproduction.

A Unified Hypothesis of Early- and Late-Onset Alzheimer's Disease Pathogenesis

Early-onset familial Alzheimer's disease (EOFAD) and late-onset sporadic AD (LOSAD) both follow a similar pathological and biochemical course that includes: neuron and synapse loss and dysfunction, microvascular damage, microgliosis, extracellular amyloid-β deposition, tau phosphorylation, formation of intracellular neurofibrillary tangles, endoreduplication and related cell cycle events in affected brain regions. Any mechanistic explanation of AD must accommodate these biochemical and neuropathological features for both forms of the disease. In this insight paper we provide a unifying hypothesis for EOFAD and LOSAD that proposes that the aberrant re-entry of terminally differentiated, post-mitotic neurons into the cell division cycle is a common pathway that explains both early and late-onset forms of AD. Cell cycle abnormalities appear very early in the disease process, prior to the appearance of plaques and tangles, and explain the biochemical (e.g. tau phosphorylation), neuropathological (e.g. neuron hypertrophy; polypoidy) and cognitive changes observed in EOFAD and LOSAD. Genetic mutations in AβPP, PSEN1, and PSEN2 that alter amyloid-β precursor protein and Notch processing drive reactivation of the cell cycle in EOFAD, while age-related reproductive endocrine dyscrasia that upregulates mitogenic TNF signaling and AβPP processing toward the amyloidogenic pathway drives reactivation of the cell cycle in LOSAD. In essence, AβPP and presenilin mutations initiate early, what endocrine dyscrasia initiates later: aberrant cell cycle re-entry of post-mitotic neurons leading to neurodegeneration and cognitive decline in AD. Inhibition of cell cycle re-entry in post-mitotic neurons may be a useful therapeutic strategy to prevent, slow or halt disease progression.