Central Role of Glucocorticoid Receptors in Alzheimer's Disease and Depression

Amyloid-β neuropathology induces bone loss in male mice by suppressing bone formation and enhancing bone resorption

Alzheimer's disease (AD) and osteoporosis often coexist in the elderly. Although observational studies suggest an association between these two diseases, the pathophysiologic link between AD and skeletal health has been poorly defined. We examined the skeletal phenotype of 5xFAD mice, an AD model with accelerated neuron-specific amyloid-β accumulation causing full-blown AD phenotype by the age of 8 months. Micro-computed tomography indicated significantly lower trabecular and cortical bone parameters in 8-month-old male, but not female, 5xFAD mice than sex-matched wild-type littermates. Dynamic histomorphometry revealed reduced bone formation and increased bone resorption, and quantitative RT-PCR showed elevated skeletal RANKL gene expression in 5xFAD males. These mice also had diminished body fat percentage with unaltered lean mass, as determined by dual-energy X-ray absorptiometry (DXA), and elevated Ucp1 mRNA levels in brown adipose tissue, consistent with increased sympathetic tone, which may contribute to the osteopenia observed in 5xFAD males. Nevertheless, no significant changes could be detected between male 5xFAD and wild-type littermates regarding the serum and skeletal concentrations of norepinephrine. Thus, brain-specific amyloid-β pathology is associated with osteopenia and appears to affect both bone formation and bone resorption. Our findings shed new light on the pathophysiologic link between Alzheimer's disease and osteoporosis.

Septohippocampal cholinergic system at the intersection of stress and cognition: Current trends and translational implications

Deficits in hippocampus-dependent memory processes are common across psychiatric and neurodegenerative disorders such as depression, anxiety and Alzheimer's disease. Moreover, stress is a major environmental risk factor for these pathologies and it exerts detrimental effects on hippocampal functioning via the activation of hypothalamic-pituitary-adrenal (HPA) axis. The medial septum cholinergic neurons extensively innervate the hippocampus. Although, the cholinergic septohippocampal pathway (SHP) has long been implicated in learning and memory, its involvement in mediating the adaptive and maladaptive impact of stress on mnemonic processes remains less clear. Here, we discuss current research highlighting the contributions of cholinergic SHP in modulating memory encoding, consolidation and retrieval. Then, we present evidence supporting the view that neurobiological interactions between HPA axis stress response and cholinergic signalling impact hippocampal computations. Finally, we critically discuss potential challenges and opportunities to target cholinergic SHP as a therapeutic strategy to improve cognitive impairments in stress-related disorders. We argue that such efforts should consider recent conceptualisations on the dynamic nature of cholinergic signalling in modulating distinct subcomponents of memory and its interactions with cellular substrates that regulate the adaptive stress response.

Geniposide improves depression-like behavior in prenatal stress male offspring through restoring HPA axis- and glucocorticoid receptor-associated dysfunction

AIMS

Prenatal stress (PS) has an important impact on the brain development of offspring, which can lead to attention deficits, anxiety and depression in offspring. Geniposide (GE) is a kind of iridoid glycoside extracted from Gardenia jasminoides Ellis. It has various pharmacological effects and has been proved that have antidepressant effects. The aim of this study was to investigate the effect of GE on depression-like behavior in PS-induced male offspring mice and explore the possible molecular mechanisms.

METHODS

We used a prenatal restraint stress model, focusing on male PS-induced offspring mice to study the effects of GE.

KEY FINDINGS

The results showed that GE administration for 4 weeks significantly improved the depression-like behavior in PS offspring mice, which was manifested by markedly increasing the sucrose preference of PS offspring and the activity in the open field test, and reducing the immobility time in the forced swimming test. In addition, GE significantly reduced the levels of hypothalamic-pituitary-adrenal (HPA) axis-related hormones and exceedingly increased the protein expression of MAP2 and GAP43 in PS offspring. Furthermore, GE increased Glucocorticoid receptors (GR) nuclear translocation in the hippocampus of PS offspring, and enhanced the expression of synaptic plasticity-related proteins.

CONCLUSION

The results of this study showed that GE exerts antidepressant effects in male PS offspring mice by regulating the HPA axis, GR function and proteins related to synaptic plasticity.

Regulation of tau by peptidyl-prolyl isomerases

Tau is an intrinsically disordered protein found abundantly in axons, where it binds to microtubules. Since tau is a central player in the dynamic microtubule network, it is highly regulated by post-translational modifications. Abnormal hyperphosphorylation and aggregation of tau characterize a group of diseases called tauopathies. A specific protein family of cis/trans peptidyl-prolyl isomerases (PPIases) can interact with tau to regulate its aggregation and neuronal resilience. Structural interactions between tau and specific PPIases have been determined, establishing possible mechanisms for tau regulation and modification. While there have been numerous in vivo studies evaluating the impact of PPIase expression on tau biology/pathology, the direct roles of PPIases have yet to be fully characterized. Different PPIases correlate to either increased or decreased levels of tau-associated degeneration. Therefore, the ability of PPIases to structurally modify and regulate tau should be further investigated due to its potential therapeutic implications for Alzheimer's disease and other tauopathies.

Ginsenoside Rg1, lights up the way for the potential prevention of Alzheimer's disease due to its therapeutic effects on the drug-controllable risk factors of Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional Chinese medicine, Shen Nong, BenCao Jing, and Compendium of Materia Medica (Bencao Gangmu), Panax ginseng, and its prescriptions have been used for the treatment of dementia, depression, weight loss, Xiaoke disease (similar to diabetes), and vertigo. All these diseases are associated with the drug-controllable risk factors for Alzheimer's disease (AD), including depression, obesity, diabetes, and hypertension. Ginsenoside Rg1, one of the main active ingredients of P. ginseng and its congener Panax notoginseng, possesses therapeutic potentials against AD and associated diseases. This suggests that ginsenoside Rg1 might have the potential for AD prevention and treatment. Although the anti-AD effects of ginsenoside Rg1 have received more attention, a systematic review of its effects on depression, obesity, diabetes, and hypertension is not available.

AIM OF THE REVIEW

This systematic literature review comprehensively summarized existing literature on the therapeutic potentials of ginsenoside Rg1 in AD prevention for the propose of providing a foundation of future research aimed at enabling the use of such drugs in clinical practice.

METHODS

Information on ginsenoside Rg1 was collected from relevant published articles identified through a literature search in electronic scientific databases (PubMed, Science Direct, and Google Scholar). The keywords used were "Ginsenoside Rg1," "Panax ginseng," "Source," "Alzheimer's disease," "Brain disorders," "Depression," "Obesity," "Diabetes," and "Hypertension."

RESULTS

The monomer ginsenoside Rg1 can be relatively easily obtained and has therapeutic potentials against AD. In vitro and in vivo experiments have demonstrated the therapeutic potentials of ginsenoside Rg1 against the drug-controllable risk factors of AD including depression, obesity, diabetes, and hypertension. Thus, ginsenoside Rg1 alleviates diseases resulting from AD risk factors by regulating multiple targets and pathways.

CONCLUSIONS

Ginsenoside Rg1 has the potentials to prevent AD by alleviating depression, obesity, diabetes, and hypertension.

Distinguishing features of depression in dementia from primary psychiatric disease

Depression is a common and devastating neuropsychiatric symptom in the elderly and in patients with dementia. In particular, nearly 80% of patients with Alzheimer's Disease dementia experience depression during disease development and progression. However, it is unknown whether the depression in patients with dementia shares the same molecular mechanisms as depression presenting as primary psychiatric disease or occurs and persists through alternative mechanisms. In this review, we discuss how the clinical presentation and treatment differ between depression in dementia and as a primary psychiatric disease, with a focus on major depressive disorder. Then, we hypothesize several molecular mechanisms that may be unique to depression in dementia such as neuropathological changes, inflammation, and vascular events. Finally, we discuss existing issues and future directions for investigation and treatment of depression in dementia.

Uncovering the Oxidative Stress Mechanisms and Targets in Alzheimer's Disease by Integrating Phenotypic Screening Data and Polypharmacology Networks

Background

The oxidative stress hypothesis is challenging the dominant position of amyloid-β (Aβ) in the field of understanding the mechanisms of Alzheimer's disease (AD), a complicated and untreatable neurodegenerative disease.

Objective

The goal of the present study was to uncover the oxidative stress mechanisms causing AD, as well as the potential therapeutic targets and neuroprotective drugs against oxidative stress mechanisms.

Methods

In this study, a systematic workflow combining pharmacological experiments and computational prediction was proposed. 222 drugs and natural products were collected first and then tested on SH-SY5Y cells to obtain phenotypic screening data on neuroprotection. The preliminary screening data were integrated with drug-target interactions (DTIs) and multi-scale biomedical data, which were analyzed with statistical tests and gene set enrichment analysis. A polypharmacology network was further constructed for investigation.

Results

340 DTIs were matched in multiple databases, and 222 cell viability ratios were calculated for experimental compounds. We identified significant potential therapeutic targets based on oxidative stress mechanisms for AD, including NR3C1, SHBG, ESR1, PGR, and AVPR1A, which might be closely related to neuroprotective effects and pathogenesis. 50% of the top 14 enriched pathways were found to correlate with AD, such as arachidonic acid metabolism and neuroactive ligand-receptor interaction. Several approved drugs in this research were also found to exert neuroprotective effects against oxidative stress mechanisms, including beclometasone, methylprednisolone, and conivaptan.

Conclusion

Our results indicated that NR3C1, SHBG, ESR1, PGR, and AVPR1A were promising therapeutic targets and several drugs may be repurposed from the perspective of oxidative stress and AD.

Altered cortical and subcortical morphometric features and asymmetries in the subjective cognitive decline and mild cognitive impairment

Introduction

This study aimed to evaluate morphological changes in cortical and subcortical regions and their asymmetrical differences in individuals with subjective cognitive decline (SCD) and mild cognitive impairment (MCI). These morphological changes may provide valuable insights into the early diagnosis and treatment of Alzheimer's disease (AD).

Methods

We conducted structural MRI scans on a cohort comprising 62 SCD patients, 97 MCI patients, and 70 age-, sex-, and years of education-matched healthy controls (HC). Using Freesurfer, we quantified surface area, thickness, the local gyrification index (LGI) of cortical regions, and the volume of subcortical nuclei. Asymmetry measures were also calculated. Additionally, we explored the correlation between morphological changes and clinical variables related to cognitive decline.

Results

Compared to HC, patients with MCI exhibited predominantly left-sided surface morphological changes in various brain regions, including the transverse temporal gyrus, superior temporal gyrus, insula, and pars opercularis. SCD patients showed relatively minor surface morphological changes, primarily in the insula and pars triangularis. Furthermore, MCI patients demonstrated reduced volumes in the anterior-superior region of the right hypothalamus, the fimbria of the bilateral hippocampus, and the anterior region of the left thalamus. These observed morphological changes were significantly associated with clinical ratings of cognitive decline.

Conclusion

The findings of this study suggest that cortical and subcortical morphometric changes may contribute to cognitive impairment in MCI, while compensatory mechanisms may be at play in SCD to preserve cognitive function. These insights have the potential to aid in the early diagnosis and treatment of AD.

The Role of Traditional Chinese Medicine Natural Products in β-Amyloid Deposition and Tau Protein Hyperphosphorylation in Alzheimer's Disease

Alzheimer's disease is a prevalent form of dementia among elderly individuals and is characterized by irreversible neurodegeneration. Despite extensive research, the exact causes of this complex disease remain unclear. Currently available drugs for Alzheimer's disease treatment are limited in their effectiveness, often targeting a single aspect of the disease and causing significant adverse effects. Moreover, these medications are expensive, placing a heavy burden on patients' families and society as a whole. Natural compounds and extracts offer several advantages, including the ability to target multiple pathways and exhibit high efficiency with minimal toxicity. These attributes make them promising candidates for the prevention and treatment of Alzheimer's disease. In this paper, we provide a summary of the common natural products used in Chinese medicine for different pathogeneses of AD. Our aim is to offer new insights and ideas for the further development of natural products in Chinese medicine and the treatment of AD.

The role of glial autophagy in Alzheimer's disease

Although Alzheimer's disease is the most pervasive neurodegenerative disorder, the mechanism underlying its development is still not precisely understood. Available data indicate that pathophysiology of this disease may involve impaired autophagy in glial cells. The dysfunction is manifested as reduced ability of astrocytes and microglia to clear abnormal protein aggregates. Consequently, excessive accumulation of amyloid beta plaques and neurofibrillary tangles activates microglia and astrocytes leading to decreased number of mature myelinated oligodendrocytes and death of neurons. These pathologic effects of autophagy dysfunction can be rescued by pharmacological activation of autophagy. Therefore, a deeper understanding of the molecular mechanisms involved in autophagy dysfunction in glial cells in Alzheimer's disease may lead to the development of new therapeutic strategies. However, such strategies need to take into consideration differences in regulation of autophagy in different types of neuroglia.

Glucocorticoid feedback paradox: a homage to Mary Dallman

As the end product of the hypothalamus-pituitary-adrenal (HPA) axis, the glucocorticoid hormones cortisol and corticosterone coordinate circadian activities, stress-coping, and adaptation to change. For this purpose, the hormone promotes energy metabolism and controls defense reactions in the body and brain. This life-sustaining action exerted by glucocorticoids occurs in concert with the autonomic nervous and immune systems, transmitters, growth factors/cytokines, and neuropeptides. The current contribution will focus on the glucocorticoid feedback paradox in the HPA-axis: the phenomenon that stress responsivity remains resilient if preceded by stress-induced secretion of glucocorticoid hormone, but not if this hormone is previously administered. Furthermore, in animal studies, the mixed progesterone/glucocorticoid antagonist RU486 or mifepristone switches to an apparent partial agonist upon repeated administration. To address these enigmas several interesting phenomena are highlighted. These include the conditional nature of the excitation/inhibition balance in feedback regulation, the role of glucose as a determinant of stress responsivity, and the potential of glucocorticoids in resetting the stress response system. The analysis of the feedback paradox provides also a golden opportunity to review the progress in understanding the role of glucocorticoid hormone in resilience and vulnerability during stress, the science that was burned deeply in Mary Dallman's emotions.

Methyleugenol Has an Antidepressant Effect in a Neuroendocrine Model: In Silico and In Vivo Evidence

Major depressive disorder is a severe mood disorder characterized by different emotions and feelings. This study investigated the antidepressant activity of the phenylpropanoid methyleugenol (ME) in adult female mice exposed to a stress model induced by dexamethasone. The animals were randomly divided into groups containing eight animals and were pre-administered with dexamethasone (64 μg/kg subcutaneously). After 165 and 180 min, they were treated with ME (25, 50 and 100 mg/kg intraperitoneally) or imipramine (10 mg/kg intraperitoneally) after 45 min and 30 min, respectively; they were then submitted to tests which were filmed. The videos were analyzed blindly. In the tail suspension test, ME (50 mg/kg) increased latency and reduced immobility time. In the splash test, ME (50 mg/kg) decreased grooming latency and increased grooming time. In the open field, there was no statistical difference for the ME groups regarding the number of crosses, and ME (50 mg/kg) increased the number of rearing and time spent in the center. Regarding in silico studies, ME interacted with dopaminergic D1 and α1 adrenergic pathway receptors and with tryptophan hydroxylase inhibitor. In the in vivo evaluation of the pathways of action, the antidepressant potential of ME (50 mg/kg) was reversed by SCH23390 (4 mg/kg intraperitoneally) dopaminergic D1 receptor, Prazosin (1 mg/kg intraperitoneally) α1 adrenergic receptor, and PCPA (4 mg/kg intraperitoneally) tryptophan hydroxylase inhibitor. Our findings indicate that ME did not alter with the locomotor activity of the animals and shows antidepressant activity in female mice with the participation of the D1, α1 and serotonergic systems.

Calcium Dyshomeostasis Drives Pathophysiology and Neuronal Demise in Age-Related Neurodegenerative Diseases

This review postulates that age-related neurodegeneration entails inappropriate activation of intrinsic pathways to enable brain plasticity through deregulated calcium (Ca2+) signalling. Ca2+ in the cytosol comprises a versatile signal controlling neuronal cell physiology to accommodate adaptive structural and functional changes of neuronal networks (neuronal plasticity) and, as such, is essential for brain function. Although disease risk factors selectively affect different neuronal cell types across age-related neurodegenerative diseases (NDDs), these appear to have in common the ability to impair the specificity of the Ca2+ signal. As a result, non-specific Ca2+ signalling facilitates the development of intraneuronal pathophysiology shared by age-related NDDs, including mitochondrial dysfunction, elevated reactive oxygen species (ROS) levels, impaired proteostasis, and decreased axonal transport, leading to even more Ca2+ dyshomeostasis. These core pathophysiological processes and elevated cytosolic Ca2+ levels comprise a self-enforcing feedforward cycle inevitably spiralling toward high levels of cytosolic Ca2+. The resultant elevated cytosolic Ca2+ levels ultimately gear otherwise physiological effector pathways underlying plasticity toward neuronal demise. Ageing impacts mitochondrial function indiscriminately of the neuronal cell type and, therefore, contributes to the feedforward cycle of pathophysiology development seen in all age-related NDDs. From this perspective, therapeutic interventions to safely restore Ca2+ homeostasis would mitigate the excessive activation of neuronal destruction pathways and, therefore, are expected to have promising neuroprotective potential.

Sex differences in metabolic phenotype and hypothalamic inflammation in the 3xTg-AD mouse model of Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is notably associated with cognitive decline resulting from impaired function of hippocampal and cortical areas; however, several other domains and corresponding brain regions are affected. One such brain region is the hypothalamus, shown to atrophy and develop amyloid and tau pathology in AD patients. The hypothalamus controls several functions necessary for survival, including energy and glucose homeostasis. Changes in appetite and body weight are common in AD, often seen several years prior to the onset of cognitive symptoms. Therefore, altered metabolic processes may serve as a biomarker for AD, as well as a target for treatment, considering they are likely both a result of pathological changes and contributor to disease progression. Previously, we reported sexually dimorphic metabolic disturbances in ~ 7-month-old 3xTg-AD mice, accompanied by differences in systemic and hypothalamic inflammation.

METHODS

In the current study, we investigated metabolic outcomes and hypothalamic inflammation in 3xTg-AD males and females at 3, 6, 9, and 12 months of age to determine when these sex differences emerge.

RESULTS

In agreement with our previous study, AD males displayed less weight gain and adiposity, as well as reduced blood glucose levels following a glucose challenge, compared to females. These trends were apparent by 6-9 months of age, coinciding with increased expression of inflammatory markers (Iba1, GFAP, TNF-α, and IL-1β) in the hypothalamus of AD males.

CONCLUSIONS

These findings provide additional evidence for sex-dependent effects of AD pathology on energy and glucose homeostasis, which may be linked to hypothalamic inflammation.

The Interface between Depression and Alzheimer's Disease. A Comprehensive Approach

Depression and Alzheimer's disease (AD) are frequent interacting diseases in the elderly with a negative impact on the quality of life of patients and caregivers. Late-life depression may be regarded either as an early symptom of AD or a risk factor for AD, depending on the context. This review was focused on the latest developments in the fields of the neurobiological basis and treatment of depression in AD. We found that some plausible hypotheses are emerging to correlate with depression in AD, such as neuroinflammation and dysimmune regulation. It seems that depression is not related to amyloid deposition, but this issue is not completely resolved. The response to antidepressants is controversial according to the evidence from 10 small double-blind randomized placebo-controlled clinical trials with antidepressants in AD patients with depression: four with sertraline, one with three arms (sertraline, mirtazapine, placebo), one with fluoxetine, one with imipramine, one with clomipramine, one with escitalopram, and one with vortioxetine. The total number of treated patients completing the trials was 638. The main criterion of a positive response was a reduction in the scores of clinical scales for depression of at least 50%. The weighted OR (odds ratio) was calculated with the method of Mantel-Haenszel: 1.29; 95% CI: 0.77-2.16. No significant differences were found compared with placebo. Antidepressants did not have a meaningful negative influence on cognition, which was measured with the mini-mental state examination (MMSE) in 18 clinical trials. Alternatives other than drugs are also discussed. Although there have been important advances in this field, pathophysiology and treatment deserve further research.

Alzheimer's disease and neuroinflammation: will new drugs in clinical trials pave the way to a multi-target therapy?

Despite extensive research, no disease-modifying therapeutic option, able to prevent, cure or halt the progression of Alzheimer's disease [AD], is currently available. AD, a devastating neurodegenerative pathology leading to dementia and death, is characterized by two pathological hallmarks, the extracellular deposits of amyloid beta (Aβ) and the intraneuronal deposits of neurofibrillary tangles (NFTs) consisting of altered hyperphosphorylated tau protein. Both have been widely studied and pharmacologically targeted for many years, without significant therapeutic results. In 2022, positive data on two monoclonal antibodies targeting Aβ, donanemab and lecanemab, followed by the 2023 FDA accelerated approval of lecanemab and the publication of the final results of the phase III Clarity AD study, have strengthened the hypothesis of a causal role of Aβ in the pathogenesis of AD. However, the magnitude of the clinical effect elicited by the two drugs is limited, suggesting that additional pathological mechanisms may contribute to the disease. Cumulative studies have shown inflammation as one of the main contributors to the pathogenesis of AD, leading to the recognition of a specific role of neuroinflammation synergic with the Aβ and NFTs cascades. The present review provides an overview of the investigational drugs targeting neuroinflammation that are currently in clinical trials. Moreover, their mechanisms of action, their positioning in the pathological cascade of events that occur in the brain throughout AD disease and their potential benefit/limitation in the therapeutic strategy in AD are discussed and highlighted as well. In addition, the latest patent requests for inflammation-targeting therapeutics to be developed in AD will also be discussed.

Sex-dependent effects of acute stress on amyloid-β in male and female mice

The risk of developing Alzheimer's disease is mediated by a combination of genetics and environmental factors, such as stress, sleep abnormalities and traumatic brain injury. Women are at a higher risk of developing Alzheimer's disease than men, even when controlling for differences in lifespan. Women are also more likely to report high levels of stress than men. Sex differences in response to stress may play a role in the increased risk of Alzheimer's disease in women. In this study, we use in vivo microdialysis to measure levels of Aβ in response to acute stress in male and female mice. We show that Aβ levels are altered differently between female and male mice (APP/PS1 and wild-type) in response to stress, with females showing significantly increased levels of Aβ while most males do not show a significant change. This response is mediated through β-arrestin involvement in Corticotrophin Releasing Factor receptor signalling pathway differences in male and female mice as male mice lacking β-arrestin show increase in Aβ in response to stress similar to females.

The pathomimetic oAβ25–35 model of Alzheimer's disease: Potential for screening of new therapeutic agents

Alzheimer's disease (AD) is the most common form of dementia in the elderly, currently affecting more than 40 million people worldwide. The two main histopathological hallmarks of AD were identified in the 1980s: senile plaques (composed of aggregated amyloid-β (Aβ) peptides) and neurofibrillary tangles (composed of hyperphosphorylated tau protein). In the human brain, both Aβ and tau show aggregation into soluble and insoluble oligomers. Soluble oligomers of Aβ include their most predominant forms - Aβ_1-40 and Aβ_1-42 - as well as shorter peptides such as Aβ_25-35 or Aβ_25-35/40. Most animal models of AD have been developed using transgenesis, based on identified human mutations. However, these familial forms of AD represent less than 1% of AD cases. In this context, the idea emerged in the 1990s to directly inject the Aβ_25-35 fragment into the rodent brain to develop an acute model of AD that could mimic the disease's sporadic forms (99% of all cases). This review aims to: (1) summarize the biological activity of Aβ_25-35, focusing on its impact on the main structural and functional alterations observed in AD (cognitive deficits, APP misprocessing, tau system dysfunction, neuroinflammation, oxidative stress, cholinergic and glutamatergic alterations, HPA axis dysregulation, synaptic deficits and cell death); and (2) confirm the interest of this pathomimetic model in AD research, as it has helped identify and characterize many molecules (marketed, in clinical development, and in preclinical testing), and to the development of alternative approaches for AD prevention and therapy. Today, the Aβ_25-35 model appears as a first-intent choice model to rapidly screen the symptomatic or neuroprotective potencies of new compounds, chemical series, or innovative therapeutic strategies.

Zebrafish Larvae Position Tracker (Z-LaP Tracker): a high-throughput deep-learning behavioral approach for the identification of calcineurin pathway-modulating drugs using zebrafish larvae

Brain function studies greatly depend on quantification and analysis of behavior. While behavior can be imaged efficiently, the quantification of specific aspects of behavior is labor-intensive and may introduce individual biases. Recent advances in deep learning and artificial intelligence-based tools have made it possible to precisely track individual features of freely moving animals in diverse environments without any markers. In the current study, we developed Zebrafish Larvae Position Tracker (Z-LaP Tracker), a modification of the markerless position estimation software DeepLabCut, to quantify zebrafish larval behavior in a high-throughput 384-well setting. We utilized the high-contrast features of our model animal, zebrafish larvae, including the eyes and the yolk for our behavioral analysis. Using this experimental setup, we quantified relevant behaviors with similar accuracy to the analysis performed by humans. The changes in behavior were organized in behavioral profiles, which were examined by K-means and hierarchical cluster analysis. Calcineurin inhibitors exhibited a distinct behavioral profile characterized by increased activity, acoustic hyperexcitability, reduced visually guided behaviors, and reduced habituation to acoustic stimuli. The developed methodologies were used to identify 'CsA-type' drugs that might be promising candidates for the prevention and treatment of neurological disorders.

Phosphodiesterase 5 inhibitor mirodenafil ameliorates Alzheimer-like pathology and symptoms by multimodal actions

Background

Alzheimer’s disease (AD) pathology is associated with complex interactions among multiple factors, involving an intertwined network of various signaling pathways. The polypharmacological approach is an emerging therapeutic strategy that has been proposed to overcome the multifactorial nature of AD by targeting multiple pathophysiological factors including amyloid-β (Aβ) and phosphorylated tau. We evaluated a blood-brain barrier penetrating phosphodiesterase 5 (PDE5) inhibitor, mirodenafil (5-ethyl-2-7-n-propyl-3,5-dihydrro-4H-pyrrolo[3,2-d]pyrimidin-4-one), for its therapeutic effects on AD with polypharmacological properties.

Methods

To evaluate the potential of mirodenafil as a disease-modifying AD agent, mirodenafil was administered to test its effects on the cognitive behaviors of the APP-C105 AD mouse model using the Morris water maze and passive avoidance tests. To investigate the mechanisms of action that underlie the beneficial disease-modifying effects of mirodenafil, human neuroblastoma SH-SY5Y cells and mouse hippocampal HT-22 cells were used to show mirodenafil-induced alterations associated with the cyclic guanosine monophosphate (cGMP)/cGMP-dependent protein kinase (PKG)/cAMP-responsive element-binding protein (CREB) pathway, apoptotic cell death, tau phosphorylation, amyloidogenesis, the autophagy-lysosome pathway, glucocorticoid receptor (GR) transcriptional activity, and the Wnt/β-catenin signaling.

Results

Here, mirodenafil is demonstrated to improve cognitive behavior in the APP-C105 mouse model. Mirodenafil not only reduced the Aβ and phosphorylated tau burdens in vivo, but also ameliorated AD pathology induced by Aβ through the modulation of the cGMP/PKG/CREB signaling pathway, glycogen synthase kinase 3β (GSK-3β) activity, GR transcriptional activity, and the Wnt/β-catenin signaling in neuronal cells. Interestingly, homodimerization and nuclear localization of GR were inhibited by mirodenafil, but not by other PDE5 inhibitors. In addition, only mirodenafil reduced the expression levels of the Wnt antagonist Dickkopf-1 (Dkk-1), thus activating the Wnt/β-catenin signaling.

Conclusions

These findings strongly suggest that the PDE5 inhibitor mirodenafil shows promise as a potential polypharmacological drug candidate for AD treatment, acting on multiple key signaling pathways involved in amyloid deposition, phosphorylated tau burden, the cGMP/PKG/CREB pathway, GSK-3β kinase activity, GR signaling, and the Wnt/β-catenin signaling. Mirodenafil administration to the APP-C105 AD mouse model also improved cognitive behavior, demonstrating the potential of mirodenafil as a polypharmacological AD therapeutic agent.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13195-022-01034-3.

Alternative Pharmacological Strategies for the Treatment of Alzheimer's Disease: Focus on Neuromodulator Function

Alzheimer's disease (AD) is a neurodegenerative disorder, comprising 70% of dementia diagnoses worldwide and affecting 1 in 9 people over the age of 65. However, the majority of its treatments, which predominantly target the cholinergic system, remain insufficient at reversing pathology and act simply to slow the inevitable progression of the disease. The most recent neurotransmitter-targeting drug for AD was approved in 2003, strongly suggesting that targeting neurotransmitter systems alone is unlikely to be sufficient, and that research into alternate treatment avenues is urgently required. Neuromodulators are substances released by neurons which influence neurotransmitter release and signal transmission across synapses. Neuromodulators including neuropeptides, hormones, neurotrophins, ATP and metal ions display altered function in AD, which underlies aberrant neuronal activity and pathology. However, research into how the manipulation of neuromodulators may be useful in the treatment of AD is relatively understudied. Combining neuromodulator targeting with more novel methods of drug delivery, such as the use of multi-targeted directed ligands, combinatorial drugs and encapsulated nanoparticle delivery systems, may help to overcome limitations of conventional treatments. These include difficulty crossing the blood-brain-barrier and the exertion of effects on a single target only. This review aims to highlight the ways in which neuromodulator functions are altered in AD and investigate how future therapies targeting such substances, which act upstream to classical neurotransmitter systems, may be of potential therapeutic benefit in the sustained search for more effective treatments.

Glucocorticoids and COVID-19

Coronavirus Disease 19 (COVID-19) is associated with high morbidity and mortality rates globally, representing the greatest health and economic challenge today. Several drugs are currently approved for the treatment of COVID-19. Among these, glucocorticoids (GCs) have received particular attention due to their anti-inflammatory and immunosuppressive effects. In fact, GC are widely used in current clinical practice to treat inflammatory, allergic and autoimmune diseases. Major mechanisms of GC action include inhibition of innate and adaptive immune activity. In particular, an important role is played by the inhibition of pro-inflammatory cytokines and chemokines, and the induction of proteins with anti-inflammatory activity. Overall, as indicated by various national and international regulatory agencies, GCs are recommended for the treatment of COVID-19 in patients requiring oxygen therapy, with or without mechanical ventilation. Regarding the use of GCs for the COVID-19 treatment of non-hospitalized patients at an early stage of the disease, many controversial studies have been reported and regulatory agencies have not recommended their use. The decision to start GC therapy should be based not only on the severity of COVID-19 disease, but also on careful considerations of the benefit/risk profile in individual patients, including monitoring of adverse events. In this review we summarize the effects of GCs on the major cellular and molecular components of the inflammatory/immune system, the benefits and the adverse common reactions in the treatment of inflammatory/autoimmune diseases, as well as in the management of COVID-19.

Imbalance in the ratio between mineralocorticoid and glucocorticoid receptors and neurodegeneration in the dentate gyrus of aged dogs

Background and Aim

Cortisol binds to mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) found in the hippocampus. The balanced expression of these receptors is essential to neuronal survival as MR and GR activations have antiapoptotic and proapoptotic effects, respectively. Given the aging changes in dogs' dentate gyrus (DG) and the possible involvement of cortisol receptors in this process, this study aimed to evaluate the expression of MR and GR and neuronal degeneration in this hippocampal region of aged dogs.

Materials and Methods

This study included cadaveric histologic hippocampus sections from six dogs aged 10 years and older (AG group) and 12 young/adult dogs aged up to 8 years (YAd group). Nissl staining and immunohistochemistry were performed to identify cells and investigate MR and GR expression, respectively. Furthermore, fluorescent labeling (fluoro-Jade B) was used to detect degenerating neurons.

Results

The AG group's polymorphic layer of the DG had a lower cell count (16%) and more degenerating neurons than the YAd group. In addition to these cellular changes, the AG group had lower MR immunoreactivity and MR-to-GR ratio. Furthermore, the lowest MR expression was associated with neuronal degeneration in the polymorphic layer of the DG of dogs.

Conclusion

An imbalance in the MR-to-GR ratio was observed in the polymorphic layer of the DG of aged dogs, along with lower MR expression and a greater number of degenerating neurons. These findings have clinical implications for understanding the decline in hippocampal memory formation associated with cognitive changes in aged dogs.

Regulatory Role of PFC Corticotropin-Releasing Factor System in Stress-Associated Depression Disorders: A Systematic Review

Stress has a substantial role in formation of psychiatric disorders especially depression. Meanwhile, impairment of the prefrontal cortex (PFC) is connected to the executive and cognitive deficits induced by the stress. Given the involvement of the corticotropin-releasing factor (CRF) in stress-related processes and knowing the fact that PFC hosts a lot of CRF receptors and CRF neurotransmissions, it can worth to look at the CRF as a potential treatment for the regulation of depression disorders induced by stress within PFC region. Here, for the first time we aimed to systematically review the effectiveness of intra-PFC CRF system in the modulation of depression dysfunction caused by the stress in clinical and preclinical models/studies. Qualified researches were combined utilizing a comprehensive search of six databases including Scopus, Pubmed, Web of Science, Sciencedirect, APA PsycNet, and Embase in April 2021 and were evaluated through proper methodological quality assessment tools. Results indicate that PFC has a remarkable role in the modulation for stress-induced depression and intra-PFC CRF receptors agonist and antagonist are very considerable for regulating these types of impairments. Specifically, elevation of both CRF immunoreactivity and gene expression were observed in human studies. In the animal studies, mostly immunoreactivity or excitatory/inhibitory currents of CRF within the PFC regulated depression dysfunction. In conclusion, reviewed studies show a positive attitude toward the CRF system in regulation of the stress-induced depression; however, obviously further investigations are required to get closer to the best treatment. Prefrontal cortex corticotropin-releasing factor system regulates stress-induced depression. CRFR1, Corticotropin-releasing factor receptor of type1; PFC, Prefrontal cortex; Minus (-) and Plus (+) signs, dysregulation and upregulation, respectively.

Cross-tissue analysis of blood and brain epigenome-wide association studies in Alzheimer's disease

To better understand DNA methylation in Alzheimer's disease (AD) from both mechanistic and biomarker perspectives, we performed an epigenome-wide meta-analysis of blood DNA methylation in two large independent blood-based studies in AD, the ADNI and AIBL studies, and identified 5 CpGs, mapped to the SPIDR, CDH6 genes, and intergenic regions, that are significantly associated with AD diagnosis. A cross-tissue analysis that combined these blood DNA methylation datasets with four brain methylation datasets prioritized 97 CpGs and 10 genomic regions that are significantly associated with both AD neuropathology and AD diagnosis. An out-of-sample validation using the AddNeuroMed dataset showed the best performing logistic regression model includes age, sex, immune cell type proportions, and methylation risk score based on prioritized CpGs in cross-tissue analysis (AUC = 0.696, 95% CI: 0.616 - 0.770, P-value = 2.78 × 10^-5). Our study offers new insights into epigenetics in AD and provides a valuable resource for future AD biomarker discovery.

Glial cells in Alzheimer's disease: From neuropathological changes to therapeutic implications

Alzheimer's disease (AD) is a neurodegenerative disorder that usually develops slowly and progressively worsens over time. Although there has been increasing research interest in AD, its pathogenesis is still not well understood. Although most studies primarily focus on neurons, recent research findings suggest that glial cells (especially microglia and astrocytes) are associated with AD pathogenesis and might provide various possible therapeutic targets. Growing evidence suggests that microglia can provide protection against AD pathogenesis, as microglia with weakened functions and impaired responses to Aβ proteins are linked with elevated AD risk. Interestingly, numerous findings also suggest that microglial activation can be detrimental to neurons. Indeed, microglia can induce synapse loss via the engulfment of synapses, possibly through a complement-dependent process. Furthermore, they can worsen tau pathology and release inflammatory factors that cause neuronal damage directly or through the activation of neurotoxic astrocytes. Astrocytes play a significant role in various cerebral activities. Their impairment can mediate neurodegeneration and ultimately the retraction of synapses, resulting in AD-related cognitive deficits. Deposition of Aβ can result in astrocyte reactivity, which can further lead to neurotoxic effects and elevated secretion of inflammatory mediators and cytokines. Moreover, glial-induced inflammation in AD can exert both beneficial and harmful effects. Understanding the activities of astrocytes and microglia in the regulation of AD pathogenesis would facilitate the development of novel therapies. In this article, we address the implications of microglia and astrocytes in AD pathogenesis. We also discuss the mechanisms of therapeutic agents that exhibit anti-inflammatory effects against AD.

MethReg: estimating the regulatory potential of DNA methylation in gene transcription

Epigenome-wide association studies often detect many differentially methylated sites, and many are located in distal regulatory regions. To further prioritize these significant sites, there is a critical need to better understand the functional impact of CpG methylation. Recent studies demonstrated that CpG methylation-dependent transcriptional regulation is a widespread phenomenon. Here, we present MethReg, an R/Bioconductor package that analyzes matched DNA methylation and gene expression data, along with external transcription factor (TF) binding information, to evaluate, prioritize and annotate CpG sites with high regulatory potential. At these CpG sites, TF-target gene associations are often only present in a subset of samples with high (or low) methylation levels, so they can be missed by analyses that use all samples. Using colorectal cancer and Alzheimer's disease datasets, we show MethReg significantly enhances our understanding of the regulatory roles of DNA methylation in complex diseases.

Stress-Induced Depression and Alzheimer's Disease: Focus on Astrocytes

Neurodegenerative diseases and depression are multifactorial disorders with a complex and poorly understood physiopathology. Astrocytes play a key role in the functioning of neurons in norm and pathology. Stress is an important factor for the development of brain disorders. Here, we review data on the effects of stress on astrocyte function and evidence of the involvement of astrocyte dysfunction in depression and Alzheimer's disease (AD). Stressful life events are an important risk factor for depression; meanwhile, depression is an important risk factor for AD. Clinical data indicate atrophic changes in the same areas of the brain, the hippocampus and prefrontal cortex (PFC), in both pathologies. These brain regions play a key role in regulating the stress response and are most vulnerable to the action of glucocorticoids. PFC astrocytes are critically involved in the development of depression. Stress alters astrocyte function and can result in pyroptotic death of not only neurons, but also astrocytes. BDNF-TrkB system not only plays a key role in depression and in normalizing the stress response, but also appears to be an important factor in the functioning of astrocytes. Astrocytes, being a target for stress and glucocorticoids, are a promising target for the treatment of stress-dependent depression and AD.

Ipriflavone as a non-steroidal glucocorticoid receptor antagonist ameliorates diabetic cognitive impairment in mice

Diabetic cognitive impairment (DCI) is a common diabetic complication with hallmarks of loss of learning ability and disorders of memory and behavior. Glucocorticoid receptor (GR) dysfunction is a main reason for neuronal impairment in brain of diabetic patients. Here, we determined that ipriflavone (IP) a clinical anti-osteoporosis drug functioned as a non-steroidal GR antagonist and efficiently ameliorated learning and memory dysfunction in both type 1 and 2 diabetic mice. The underlying mechanism has been intensively investigated by assay against the diabetic mice with GR-specific knockdown in the brain by injection of adeno-associated virus (AAV)-ePHP-si-GR. IP suppressed tau hyperphosphorylation through GR/PI3K/AKT/GSK3β pathway, alleviated neuronal inflammation through GR/NF-κB/NLRP3/ASC/Caspase-1 pathway, and protected against synaptic impairment through GR/CREB/BDNF pathway. To our knowledge, our work might be the first to expound the detailed mechanism underlying the amelioration of non-steroidal GR antagonist on DCI-like pathology in mice and report the potential of IP in treatment of DCI.

Seizure activity triggers tau hyperphosphorylation and amyloidogenic pathways

OBJECTIVE

Although epilepsies and neurodegenerative disorders show pathophysiological similarities, their direct functional associations are unclear. Here, we tested the hypothesis that experimental seizures can induce tau hyperphosphorylation and amyloidogenic modifications over time, with intersections with neuroinflammation.

METHODS

We used a model of mesial temporal lobe epilepsy (MTLE) where unilateral intrahippocampal injection of kainic acid (KA) in C57BL/6 mice elicits epileptogenesis and spontaneous focal seizures. We used a model of generalized status epilepticus (SE) obtained by intraperitoneal KA injection in C57BL/6 mice. We performed analyses and cross-comparisons according to a schedule of 72 h, 1 week, and 8 weeks after KA injection.

RESULTS

In experimental MTLE, we show AT100, PHF1, and CP13 tau hyperphosphorylation during epileptogenesis (72 h-1 week) and long-term (8 weeks) during spontaneous seizures in the ipsilateral hippocampi, the epileptogenic zone. These pathological modifications extended to the contralateral hippocampus, a seizure propagating zone with no histological lesion or sclerosis. Two kinases, Cdk5 and GSK3β, implicated in the pathological phosphorylation of tau, were activated. In this MTLE model, the induction of the amyloidogenic pathway (APP, C99, BACE1) was prominent and long-lasting in the epileptogenic zone. These Alzheimer's disease (AD)-relevant markers, established during seizure progression and recurrence, reciprocated an enduring glial (GFAP, Iba1) inflammation and the inadequate activation of the endogenous, anti-inflammatory, glucocorticoid receptor system. By contrast, a generalized SE episode provoked a predominantly transient induction of tau hyperphosphorylation and amyloidogenic markers in the hippocampus, along with resolving inflammation. Finally, we identified overlapping profiles of long-term hippocampal tau hyperphosphorylation by comparing MTLE to J20 mice, the latter a model relevant to AD.

SIGNIFICANCE

MTLE and a generalized SE prompt persistent and varying tau hyperphosphorylation or amyloidogenic modifications in the hippocampus. In MTLE, an AD-relevant molecular trajectory intertwines with neuroinflammation, spatiotemporally involving epileptogenic and nonlesional seizure propagating zones.

Hippocampus and its involvement in Alzheimer's disease: a review

Hippocampus is the significant component of the limbic lobe, which is further subdivided into the dentate gyrus and parts of Cornu Ammonis. It is the crucial region for learning and memory; its sub-regions aid in the generation of episodic memory. However, the hippocampus is one of the brain areas affected by Alzheimer's (AD). In the early stages of AD, the hippocampus shows rapid loss of its tissue, which is associated with the functional disconnection with other parts of the brain. In the progression of AD, atrophy of medial temporal and hippocampal regions are the structural markers in magnetic resonance imaging (MRI). Lack of sirtuin (SIRT) expression in the hippocampal neurons will impair cognitive function, including recent memory and spatial learning. Proliferation, differentiation, and migrations are the steps involved in adult neurogenesis. The microglia in the hippocampal region are more immunologically active than the other regions of the brain. Intrinsic factors like hormones, glia, and vascular nourishment are instrumental in the neural stem cell (NSC) functions by maintaining the brain's microenvironment. Along with the intrinsic factors, many extrinsic factors like dietary intake and physical activity may also influence the NSCs. Hence, pro-neurogenic lifestyle could delay neurodegeneration.

Differential expression of long non-coding RNAs in the hippocampus of mice exposed to PM2.5 in Dalian, China

Evidence is mounting that PM_2.5 exposure could lead to learning disability, memory deficits, and cognitive impairment; however, the underlying mechanisms are still not well demonstrated yet. Long non-coding RNAs (LncRNAs) play a crucial role in many human diseases. Although the relationship of Alzheimer's disease (AD) and lncRNAs have been discovered, the role of lncRNA in AD-like phenotype induced by PM_2.5 needs further exploration. In this study, we profiled the expression of messenger RNAs (mRNAs) and lncRNAs in hippocampus after confirming the AD-like changes in mice. Compared with the control group, a total of 478 mRNAs and 151 lncRNAs were dysregulated after PM_2.5 exposure. ECM-receptor interaction, focal adhesion, complement and coagulation cascades, and AGE-RAGE signaling pathway were found dysregulated through lncRNA-co-expressed genes analysis based on the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Meanwhile, the genes related to microglia were significantly altered, such as CX3CR1, CD163, lncRNA Gm44750, and lncRNA Gm43509. Above evidences suggested that microglia-related lncRNAs dysregulation probably plays a crucial role in PM_2.5exposure-associated learning and memory deficits.

Multifunctional amino acids empowering bifunctional biosensing platform for depression study

Poor availability of objective approaches hinders effective diagnosis and treatment for depression. Biosensors provide a promising platform for the development of quantitative and practical methods for disease detection, as well as for drug discovery. Here, we developed an electrochemical biosensor has been established with the ability to simply and accurately detect the trace glucocorticoid receptor alpha (GRα), as a key biomarker of depression, in both hippocampus and blood cells. The integration of amino-ion graphene oxide (IL-rGO) and amino acid-coated gold nanoparticles (AA-AuNPs) via green synthesis remarkably magnifies the electrochemical signals, where amino acids play multiple roles as reducing agents, stabilizers, and bridging agents. After the optimization among AA-AuNPs@IL-rGO nanocomposites based on five typical amino acids, a biosensing surface has been constructed to implement analysis in real samples as a bifunctional platform. The obtained biosensor exhibited a remarkably low limit of detection (0.283 pg mL^-1) and could thus sensitively identify the GRα differences in healthy and depressive rats with and without fluoxetine. The electrochemical biosensor developed herein was not only outstandingly sensitive but also simple to use and labor-saving, making it a promising all-in-one platform for depression diagnosis and drug discovery.

Chronic Glucocorticoids Consumption Triggers and Worsens Experimental Alzheimer's Disease-Like Pathology by Detrimental Immune Modulations

INTRODUCTION

Among the risk factors identified in the sporadic forms of Alzheimer's disease (AD), environmental and lifestyle elements are of growing interest. Clinical observations suggest that stressful events can anticipate AD onset, while stress-related disorders can promote AD. Here, we tested the hypothesis that a chronic treatment with glucocorticoids is sufficient to trigger or exacerbate AD molecular hallmarks.

METHODS

We first validated a rat model of experimental chronic glucocorticoids (GC) consumption (corticosterone [CORT] in drinking water for 4 weeks). Then, to evaluate the consequences of chronic GC consumption on the onset of amyloid-β (Aβ) toxicity, animals chronically treated with GC were intracerebroventricularly injected with an oligomeric solution of Aβ25-35 (oAβ) (acute model of AD). We evaluated AD-related cognitive deficits and pathogenic mechanisms, with a special emphasis on neuroinflammatory markers.

RESULTS

Chronic CORT consumption caused the inhibition of the nonamyloidogenic pathways, the impairment of Aβ clearance processes and the induction of amyloidogenic pathways in the hippocampus. The principal enzymes involved in glucocorticoid receptor activation and Tau phosphorylation were upregulated. Importantly, the AD-like phenotype triggered by chronic CORT was analogous to the one caused by oAβ. These molecular commonalities across models were independent from inflammation, as chronic CORT was immunosuppressive while oAβ was pro-inflammatory. When chronic CORT consumption anticipated the induction of the oAβ pathology, we found a potentiation of neuroinflammatory processes associated with an exacerbation of synaptic and memory deficits but also an aggravation of AD-related hallmarks.

DISCUSSION/CONCLUSION

This study unravels new functional outcomes identifying chronic CORT consumption as a main risk factor for AD and suggests that glucocorticoid-based therapies should be prescribed with caution in populations with AD risk.

Drug Delivery Challenges in Brain Disorders across the Blood-Brain Barrier: Novel Methods and Future Considerations for Improved Therapy

Due to the physiological and structural properties of the blood-brain barrier (BBB), the delivery of drugs to the brain poses a unique challenge in patients with central nervous system (CNS) disorders. Several strategies have been investigated to circumvent the barrier for CNS therapeutics such as in epilepsy, stroke, brain cancer and traumatic brain injury. In this review, we summarize current and novel routes of drug interventions, discuss pharmacokinetics and pharmacodynamics at the neurovascular interface, and propose additional factors that may influence drug delivery. At present, both technological and mechanistic tools are devised to assist in overcoming the BBB for more efficient and improved drug bioavailability in the treatment of clinically devastating brain disorders.

Multimodal single-cell/nucleus RNA sequencing data analysis uncovers molecular networks between disease-associated microglia and astrocytes with implications for drug repurposing in Alzheimer's disease

Because disease-associated microglia (DAM) and disease-associated astrocytes (DAA) are involved in the pathophysiology of Alzheimer's disease (AD), we systematically identified molecular networks between DAM and DAA to uncover novel therapeutic targets for AD. Specifically, we develop a network-based methodology that leverages single-cell/nucleus RNA sequencing data from both transgenic mouse models and AD patient brains, as well as drug-target network, metabolite-enzyme associations, the human protein-protein interactome, and large-scale longitudinal patient data. Through this approach, we find both common and unique gene network regulators between DAM (i.e., PAK1, MAPK14, and CSF1R) and DAA (i.e., NFKB1, FOS, and JUN) that are significantly enriched by neuro-inflammatory pathways and well-known genetic variants (i.e., BIN1). We identify shared immune pathways between DAM and DAA, including Th17 cell differentiation and chemokine signaling. Last, integrative metabolite-enzyme network analyses suggest that fatty acids and amino acids may trigger molecular alterations in DAM and DAA. Combining network-based prediction and retrospective case-control observations with 7.2 million individuals, we identify that usage of fluticasone (an approved glucocorticoid receptor agonist) is significantly associated with a reduced incidence of AD (hazard ratio [HR] = 0.86, 95% confidence interval [CI] 0.83-0.89, P < 1.0 × 10-8). Propensity score-stratified cohort studies reveal that usage of mometasone (a stronger glucocorticoid receptor agonist) is significantly associated with a decreased risk of AD (HR = 0.74, 95% CI 0.68-0.81, P < 1.0 × 10-8) compared to fluticasone after adjusting age, gender, and disease comorbidities. In summary, we present a network-based, multimodal methodology for single-cell/nucleus genomics-informed drug discovery and have identified fluticasone and mometasone as potential treatments in AD.

Intact circadian rhythm despite cortisol hypersecretion in Alzheimer's disease: A meta-analysis

Hypersecretion of the glucocorticoid steroid hormone cortisol by individuals with Alzheimer's disease (AD) has been suspected for several decades, during which time dozens of examinations of this phenomenon have been conducted and published. The goals of this investigation were to summarize this sizeable body of literature, test whether participant and methodological characteristics modify the magnitude of the AD-associated basal cortisol hypersecretion, and examine whether cortisol circadian rhythmicity is maintained among individuals with AD. To this end, the present meta-analysis and systematic review examined over 300 comparisons of indices of basal HPA-axis functioning between individuals with AD and cognitively normal older adults. AD was associated with basal cortisol elevations (g = 0.45) but the magnitude of the effect was not systematically impacted by any of the participant characteristics considered or the time-of-day of the cortisol sampling. Further, there was no evidence of group differences among direct indices of circadian rhythmicity such as the cortisol awakening response or the diurnal cortisol slope. These results suggest that basal hypersecretion of cortisol, but not circadian dysrhythmia, is characteristic of individuals with AD. Mechanistically, the observed hypersecretion is consistent with the theorized AD-driven deterioration of the hippocampus and subsequent reduction in hypothalamic-pituitary-adrenal axis inhibition. Further investigation is warranted to elucidate the role and timing of cortisol elevations in the progression of AD.

Chronic stress induces NPD-like behavior in APPPS1 and WT mice with subtle differences in gene expression

Neuropsychiatric disturbances (NPDs) are considered hallmarks of Alzheimer's disease (AD). Nevertheless, treatment of these symptoms has proven difficult and development of safe and effective treatment options is hampered by the limited understanding of the underlying pathophysiology. Thus, robust preclinical models are needed to increase knowledge of NPDs in AD and develop testable hypotheses and novel treatment options. Abnormal activity of the hypothalamic-pituitary-adrenal (HPA) axis is implicated in many psychiatric symptoms and might contribute to both AD and NPDs development and progression. We aimed to establish a mechanistic preclinical model of NPD-like behavior in the APPPS1 mouse model of AD and wildtype (WT) littermates. In APPPS1 and WT mice, we found that chronic stress increased anxiety-like behavior and altered diurnal locomotor activity suggestive of sleep disturbances. Also, chronic stress activated the HPA axis, which, in WT mice, remained heightened for additional 3 weeks. Chronic stress caused irregular expression of circadian regulatory clock genes (BMAL1, PER2, CRY1 and CRY2) in both APPPS1 and WT mice. Interestingly, APPPS1 and WT mice responded differently to chronic stress in terms of expression of serotonergic markers (5-HT_1A receptor and MAOA) and inflammatory genes (IL-6, STAT3 and ADMA17). These findings indicate that, although the behavioral response to chronic stress might be similar, the neurobiochemical response was different in APPPS1 mice, which is an important insight in the efforts to develop safe and effective treatments options for NPDs in AD patients. Further work is needed to substantiate these findings.

The plasma peptides of Alzheimer's disease

Background

A practical strategy to discover proteins specific to Alzheimer’s dementia (AD) may be to compare the plasma peptides and proteins from patients with dementia to normal controls and patients with neurological conditions like multiple sclerosis or other diseases. The aim was a proof of principle for a method to discover proteins and/or peptides of plasma that show greater observation frequency and/or precursor intensity in AD. The endogenous tryptic peptides of Alzheimer’s were compared to normals, multiple sclerosis, ovarian cancer, breast cancer, female normal, sepsis, ICU Control, heart attack, along with their institution-matched controls, and normal samples collected directly onto ice.

Methods

Endogenous tryptic peptides were extracted from blinded, individual AD and control EDTA plasma samples in a step gradient of acetonitrile for random and independent sampling by LC–ESI–MS/MS with a set of robust and sensitive linear quadrupole ion traps. The MS/MS spectra were fit to fully tryptic peptides within proteins identified using the X!TANDEM algorithm. Observation frequency of the identified proteins was counted using SEQUEST algorithm. The proteins with apparently increased observation frequency in AD versus AD Control were revealed graphically and subsequently tested by Chi Square analysis. The proteins specific to AD plasma by Chi Square with FDR correction were analyzed by the STRING algorithm. The average protein or peptide log₁₀ precursor intensity was compared across disease and control treatments by ANOVA in the R statistical system.

Results

Peptides and/or phosphopeptides of common plasma proteins such as complement C2, C7, and C1QBP among others showed increased observation frequency by Chi Square and/or precursor intensity in AD. Cellular gene symbols with large Chi Square values (χ2 ≥ 25, p ≤ 0.001) from tryptic peptides included KIF12, DISC1, OR8B12, ZC3H12A, TNF, TBC1D8B, GALNT3, EME2, CD1B, BAG1, CPSF2, MMP15, DNAJC2, PHACTR4, OR8B3, GCK, EXOSC7, HMGA1 and NT5C3A among others. Similarly, increased frequency of tryptic phosphopeptides were observed from MOK, SMIM19, NXNL1, SLC24A2, Nbla10317, AHRR, C10orf90, MAEA, SRSF8, TBATA, TNIK, UBE2G1, PDE4C, PCGF2, KIR3DP1, TJP2, CPNE8, and NGF amongst others. STRING analysis showed an increase in cytoplasmic proteins and proteins associated with alternate splicing, exocytosis of luminal proteins, and proteins involved in the regulation of the cell cycle, mitochondrial functions or metabolism and apoptosis. Increases in mean precursor intensity of peptides from common plasma proteins such as DISC1, EXOSC5, UBE2G1, SMIM19, NXNL1, PANO, EIF4G1, KIR3DP1, MED25, MGRN1, OR8B3, MGC24039, POLR1A, SYTL4, RNF111, IREB2, ANKMY2, SGKL, SLC25A5, CHMP3 among others were associated with AD. Tryptic peptides from the highly conserved C-terminus of DISC1 within the sequence MPGGGPQGAPAAAGGGGVSHRAGSRDCLPPAACFR and ARQCGLDSR showed a higher frequency and highest intensity in AD compared to all other disease and controls.

Conclusion

Proteins apparently expressed in the brain that were directly related to Alzheimer’s including Nerve Growth Factor (NFG), Sphingomyelin Phosphodiesterase, Disrupted in Schizophrenia 1 (DISC1), the cell death regulator retinitis pigmentosa (NXNl1) that governs the loss of nerve cells in the retina and the cell death regulator ZC3H12A showed much higher observation frequency in AD plasma vs the matched control. There was a striking agreement between the proteins known to be mutated or dis-regulated in the brains of AD patients with the proteins observed in the plasma of AD patients from endogenous peptides including NBN, BAG1, NOX1, PDCD5, SGK3, UBE2G1, SMPD3 neuronal proteins associated with synapse function such as KSYTL4, VTI1B and brain specific proteins such as TBATA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12014-021-09320-2.

Combined exposure of alumina nanoparticles and chronic stress exacerbates hippocampal neuronal ferroptosis via activating IFN-γ/ASK1/JNK signaling pathway in rats

Alumina nanoparticles (AlNPs) exposure causes hippocampal-dependent cognitive dysfunction. However, whether chronic stress exacerbates AlNPs-induced hippocampal lesion and its mechanism remains unclear. This study was aimed to investigate the combined effects and mechanisms of AlNPs and chronic stress on the hippocampal lesion. The behavioral tests demonstrated that combined exposure to AlNPs and chronic restraint stress (CRS) worsened both cognition and depression-like behavior than exposed to AlNPs and CRS alone. Microstructural and ultrastructural observations showed that combined exposure to AlNPs and CRS exacerbated hippocampal damage. Both AlNPs and CRS induced hippocampal neuronal ferroptosis, presenting as iron and glutamate metabolism disorder, GPX4 fluorescence of neurons decrease, LPO and ROS levels increase, and FJB-positive neurons increase. Meanwhile, combined exposure to AlNPs and CRS exacerbated hippocampal neuronal ferroptosis. Mechanism investigation revealed that combined exposure to AlNPs and CRS activated IFN-γ/ASK1/JNK signaling pathway. Furthermore, IFN-γ neutralizing antibody R4-6A2 effectively inhibited the activation of IFN-γ/ASK1/JNK signaling pathway, alleviated hippocampal neuronal ferroptosis and improved cognition ability. ASK1 inhibitor GS-4997 also improved hippocampal neuronal ferroptosis and cognitive dysfunction by inhibiting ASK1/JNK signaling pathway. Together, these results demonstrate that combined exposure to AlNPs and CRS exacerbates hippocampal neuronal ferroptosis via activating IFN-γ/ASK1/JNK signaling pathway.

A Novel Methodology Using Dexamethasone to Induce Neuronal Differentiation in the CNS-Derived Catecholaminergic CAD Cells

The Cath.a-differentiated (CAD) cell line is a central nervous system-derived catecholaminergic cell line originating from tyrosine hydroxylase (TH)-producing neurons located around the locus coeruleus area of the mouse brain. CAD cells have been used as an in vitro model for cellular and molecular studies due to their ability to differentiate under serum-free media conditions. However, the lack of serum-derived survival factors, limits the longevity for differentiated CAD cells to be maintained in healthy conditions; thereby, limiting their use in long-term culture studies. Here, we present a novel differentiation method that utilizes dexamethasone (Dex), a synthetic glucocorticoid receptor agonist. Specifically, we discovered that the addition of 100 µM of Dex into the 1% fetal bovine serum (FBS)-supplemented media effectively induced neuronal differentiation of CAD cells, as characterized by neurite formation and elongation. Dex-differentiated CAD cells exited the cell cycle, stopped proliferating, extended the neurites, and expressed neuronal markers. These effects were dependent on the glucocorticoid receptors (GR) as they were abolished by GR knockdown. Importantly, Dex-differentiated CAD cells showed longer survival duration than serum-free differentiated CAD cells. In addition, RNA-sequencing and qPCR data demonstrate that several genes involved in proliferation, neuronal differentiation, and survival pathways were differentially expressed in the Dex-differentiated cells. This is the first study to reveal Dex as a novel differentiation methodology used to generate postmitotic neuronal CAD cells, which may be utilized as an in vitro neuronal model for cellular and molecular neurobiology research.

Identification of phytochemicals from North African plants for treating Alzheimer's diseases and of their molecular targets by in silico network pharmacology approach

BACKGROUND

The global social expenses of Alzheimer's disease (AD) have been increased to US$1 trillion due to high cost, side-effects, and low efficiency of the current AD-therapies. Another reason is the lack of preventive drugs and the low-income situation of Asian and African countries. Accordingly, patients rather prefer traditional herbal remedies. Network-pharmacology has been a well-established method for the visualization and the construction of disorder target protein-drug framework. This could aid in the identification of drugs molecular-mechanisms.

AIM

The aim of this study is to investigate the phytochemical constituents that could target Alzheimer's disease from the North African plants. This could be done by exploring their possible mechanisms of action through molecular network pharmacology-based approach.

EXPERIMENTAL PROCEDURE

The Phytochemical-compounds of North-African plants (NAP) have been accessed from open-databank. ADME-screening has been conducted for filtering of the NAP phytochemical-constituents utilizing Qikprop-software. The open STITCH databank has been utilized for the prediction of the phytochemical-constituents target-proteins; UniProt and TDD-DB databanks have been utilized for distinguishing AD-related proteins. Phytochemical constituent-target protein (C-T) and plant-phytochemical constituent-target protein (P-C-T) frameworks have been assembled utilizing Cytoscape to interpret the anti-Alzheimer's disease mechanism of action of the targeted phytochemical constituents.

RESULTS

The NAP 6842 phytochemical-constituents (from more than 1000 plants) have been exposed to ADME and CNS modulating filtration, generating 94 phytochemical-constituents which have been subjected to target-prediction investigation. The 94 phytochemical-constituents and the 4 AD-identified targets have been associated through 155 edges which formed the main pathways related to AD. Cuparene, alpha-selinene, beta-sesquiphellandrene, calamenene, 2-4-dimethylheptane, undecane, n-tetradecane, hexadecane, nonadecane, n-eicosane, and heneicosane have had C-T network highest combined-score, whilst the proteins MAO-B, HMG-CoA, BACE1, and GCR have been the most enriched ones by comprising the uppermost combined-scores of C-T. Hypericum perforatum, Piper nigrum, Juniperus communis, Levisticum officinale, Origanum vulgare acquired the uppermost number of P-C-Target interactions.

CONCLUSION

The phytochemical-targets prediction of NAP utilizing molecular-network pharmacology-based investigation has paved the way for networking multi-target, multi-constituent, and multi-pathway mechanisms. This may introduce potential future targets for the regulation and the management of Alzheimer's disease.

TAXONOMY CLASSIFICATION BY EVISE

Alzheimer's disease, Network pharmacology, In-silico computer based approach.

Susceptibility to chronic immobilization stress-induced depressive-like behaviour in middle-aged female mice and accompanying changes in dopamine D1 and GABAA receptors in related brain regions

Background

Middle-aged females, especially perimenopausal females, are vulnerable to depression, but the potential mechanism remains unclear. Dopaminergic and GABAergic system dysfunction is involved in the pathophysiology of depression. In the current study, we used 2-month-old and 11-month-old C57BL/6 mice as young and middle-aged mice, respectively. Chronic immobilization stress (CIS) was used to induce depressive-like behaviour, and the sucrose preference test (SPT), tail suspension test (TST) and forced swim test (FST) were used to assess these behaviours. We then measured the mRNA levels of dopamine receptor D1 (DRD1) and the GABA_A receptors GABRA1, GABRB2 and GABRG2 in the nucleus accumbens (NAc) and prefrontal cortex (PFC).

Results

We found that immobility time in the FST was significantly increased in the middle-aged mice compared with the middle-aged control mice and the young mice. In addition, the preference for sucrose water was reduced in the middle-aged mice compared with the middle-aged control mice. However, CIS did not induce obvious changes in the performance of the young mice in our behavioural tests. Moreover, the middle-aged mice exhibited equal immobility times as the young mice in the absence of stress. Decreases in the mRNA levels of DRD1, GABRA1, and GABRB2 but not GABRG2 were found in the NAc and PFC in the middle-aged mice in the absence of stress. Further decreases in the mRNA levels of DRD1 in the NAc and GABRG2 in the NAc and PFC were found in the middle-aged mice subjected to CIS.

Conclusions

Our results suggested that ageing could not directly induce depression in the absence of stress. However, ageing could induce susceptibility to depression in middle-aged mice in the presence of stress. CIS-induced decreases in DRD1 and GABRG2 levels might be involved in the increase in susceptibility to depression in this context.

In Silico Study Examining New Phenylpropanoids Targets with Antidepressant Activity

BACKGROUND

Natural products, such as phenylpropanoids, which are found in essential oils derived from aromatic plants, have been explored during non-clinical psychopharmacology studies, to discover new molecules with relevant pharmacological activities in the central nervous system, especially antidepressant and anxiolytic activities. Major depressive disorder is a highly debilitating psychiatric disorder and is considered to be a disabling public health problem, worldwide, as a primary factor associated with suicide. Current clinically administered antidepressants have late-onset therapeutic actions, are associated with several side effects, and clinical studies have reported that some patients do not respond well to treatment or reach complete remission.

OBJECTIVE

To review important new targets for antidepressant activity and to select phenylpropanoids with antidepressant activity, using Molegro Virtual Docker and Ossis Data Warris, and to verify substances with more promising antidepressant activity.

RESULTS AND CONCLUSION

An in silico molecular modeling study, based on homology, was conducted to determine the three-dimensional structure of the 5-hydroxytryptamine 2A receptor (5- HT2AR), then molecular docking studies were performed and the predisposition for cytotoxicity risk among identified molecules was examined. A model for 5-HT2AR homology, with satisfactory results, was obtained indicating the good stereochemical quality of the model. The phenylpropanoid 4-allyl-2,6-dimethoxyphenol showed the lowest binding energy for 5-HT2AR, with results relevant to the L-arginine/nitric oxide (NO)/cGMP pathway, and showed no toxicity within the parameters of mutagenicity, carcinogenicity, reproductive system toxicity, and skin-tissue irritability, when evaluated in silico; therefore, this molecule can be considered promising for the investigation of antidepressant activity.

Navigating Alzheimer's Disease via Chronic Stress: The Role of Glucocorticoids

Alzheimer's disease (AD) is a chronic intensifying incurable progressive disease leading to neurological deterioration manifested as impairment of memory and executive brain functioning affecting the physical ability like intellectual brilliance, common sense in patients. The recent therapeutic approach in Alzheimer's disease is only the symptomatic relief further emerging the need for therapeutic strategies to be targeted in managing the underlying silent killing progression of dreaded pathology. Therefore, the current research direction is focused on identifying the molecular mechanisms leading to the evolution of the understanding of the neuropathology of Alzheimer's disease. The resultant saturation in the area of current targets (amyloid β, τ Protein, oxidative stress etc.) has led the scientific community to rethink of the mechanistic neurodegenerative pathways and reprogram the current research directions. Although, the role of stress has been recognized for many years and contributing to the development of cognitive impairment, the area of stress has got the much-needed impetus recently and is being recognized as a modifiable menace for AD. Stress is an unavoidable human experience that can be resolved and normalized but chronic activation of stress pathways unsettle the physiological status. Chronic stress mediated activation of neuroendocrine stimulation is generally linked to a high risk of developing AD. Chronic stress-driven physiological dysregulation and hypercortisolemia intermingle at the neuronal level and leads to functional (hypometabolism, excitotoxicity, inflammation) and anatomical remodeling of the brain architecture (senile plaques, τ tangles, hippocampal atrophy, retraction of spines) ending with severe cognitive deterioration. The present review is an effort to collect the most pertinent evidence that support chronic stress as a realistic and modifiable therapeutic earmark for AD and to advocate glucocorticoid receptors as therapeutic interventions.

Inflammation/bioenergetics-associated neurodegenerative pathologies and concomitant diseases: a role of mitochondria targeted catalase and xanthophylls

Various inflammatory stimuli are able to modify or even "re-program" the mitochondrial metabolism that results in generation of reactive oxygen species. In noncommunicable chronic diseases such as atherosclerosis and other cardiovascular pathologies, type 2 diabetes and metabolic syndrome, these modifications become systemic and are characterized by chronic inflammation and, in particular, "neuroinflammation" in the central nervous system. The processes associated with chronic inflammation are frequently grouped into "vicious circles" which are able to stimulate each other constantly amplifying the pathological events. These circles are evidently observed in Alzheimer's disease, atherosclerosis, type 2 diabetes, metabolic syndrome and, possibly, other associated pathologies. Furthermore, chronic inflammation in peripheral tissues is frequently concomitant to Alzheimer's disease. This is supposedly associated with some common genetic polymorphisms, for example, Apolipoprotein-E ε4 allele carriers with Alzheimer's disease can also develop atherosclerosis. Notably, in the transgenic mice expressing the recombinant mitochondria targeted catalase, that removes hydrogen peroxide from mitochondria, demonstrates the significant pathology amelioration and health improvements. In addition, the beneficial effects of some natural products from the xanthophyll family, astaxanthin and fucoxanthin, which are able to target the reactive oxygen species at cellular or mitochondrial membranes, have been demonstrated in both animal and human studies. We propose that the normalization of mitochondrial functions could play a key role in the treatment of neurodegenerative disorders and other noncommunicable diseases associated with chronic inflammation in ageing. Furthermore, some prospective drugs based on mitochondria targeted catalase or xanthophylls could be used as an effective treatment of these pathologies, especially at early stages of their development.

β-amyloid pathology is not associated with depression in a large community sample autopsy study

BACKGROUND

Depression has been associated with dementia. This study aimed to verify if β-amyloid Alzheimer's disease-type burden was associated with lifetime major depressive disorder (MDD) and with current depressive symptoms in a large population-based autopsy study.

METHODS

We included 1013 deceased subjects submitted to autopsy (mean age=74.3±11.6 years, 49% men) in a community sample. β-amyloid burden was measured in all cases based on the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) criteria for presence and density of neuritic plaques. Lifetime MDD was defined when at least one previous episode according to the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders - DSM (SCID). Depressive symptoms and cognitive impairment were determined using the depression item of the Neuropsychiatric Inventory (D-NPI>0) and the Clinical Dementia Rating scale (CDR>0.5) respectively.

RESULTS

Lifetime MDD, late life depression (LLD) and current depressive symptoms were associated with cognitive impairment (p<0.001). Additionally, neuritic plaques were associated with cognitive impairment (p<0.001). Moderate or frequent neurite plaque density was not associated with MDD, LLD or current depressive symptoms in multiple logistic models adjusted for age, gender, and cognitive impairment.

LIMITATIONS

In this cross-sectional study, all neuropsychiatric and cognitive assessment were based on informant-report of deceased participants.

CONCLUSIONS

Different clinical depictions of depression were associated with dementia in this large community sample of elderly individuals with multiethnic backgrounds. Notwithstanding, they were unrelated to β-amyloid pathology in the brain areas studied. The link between depression and dementia might be complex and determined by multiple factors.

Beta amyloid-induced time-dependent learning and memory impairment: involvement of HPA axis dysfunction

Aβ aggregation is one of the pathological biomarkers of Alzheimer's disease (AD). However, the possible mechanism related to Aβ-induced pathological signaling pathway is still unknown. In the present study, Aβ1-42-induced time-dependent memory impairment and its possible relationship to hypothalamic-pituitary-adrenal (HPA) axis hyperactivity were examined. Aβ1-42-treated mice significantly impaired acquisition activity in the learning curve at 10 days, 1 and 4 months in the Morris water-maze (MWM) task. This learning activity was back to normal at 8 months after Aβ1-42 treatment. In the probe trial test, Aβ1-42-treated mice needed longer latencies to touch the precious platform location and fewer numbers of crossing from 10 days to 4 months after microinjection. This Aβ1-42 induced memory loss was consistent with the results of the step-down passive avoidance test. The HPA axis related parameters, such as corticosterone (CORT) level in the serum, glucocorticoid receptor (GR) and corticotropin-releasing factor receptor (CRF-R) expression in the frontal cortex and hippocampus increased in Aβ1-42-treated mice from 10 days to 4 months. While the downstream molecules phosphorylation of cyclic AMP response element binding (pCREB) and brain-derived neurotrophic factor (BDNF) expression decreased during this time. These effects were back to normal 8 months after treatment with Aβ1-42. Altogether, our results suggested that Aβ1-42 induced significant learning and memory impairment, which is involved in HPA axis dysfunction.

Endocrine stress responsivity and social memory in 3xTg-AD female and male mice: A tale of two experiments

Stress confers risk for the development and progression of Alzheimer's disease (AD). Relative to men, women are disproportionately more likely to be diagnosed with this neurodegenerative disease. We hypothesized that sex differences in endocrine stress responsiveness may be a factor in this statistic. To test this hypothesis, we assessed basal and stress-induced corticosterone, social recognition, and coat state deterioration (surrogate for depression-like behavior) in male and female 3xTg-AD mice. Prior to reported amyloid plaque deposition, 3xTg females (4 months), but not 3xTg males, had heightened corticosterone responses to restraint exposure. Subsequently, only 3xTg females (6 months) displayed deficits in social memory concomitant with prominent β-amyloid (Aβ) immunostaining. These data suggest that elevated corticosterone stress responses may precede cognitive impairments in genetically vulnerable females. 3xTg mice of both sexes exhibited coat state deterioration relative to same-sex controls. Corticolimbic glucocorticoid receptor (GR) dysfunction is associated with glucocorticoid hypersecretion and cognitive impairment. Our findings indicate sex- and brain-region specific effects of genotype on hippocampal and amygdala GR protein expression. Because olfactory deficits may impede social recognition, in Experiment 2, we assessed olfaction and found no differences between genotypes. Notably, in this cohort, heightened corticosterone stress responses in 3xTg females was not accompanied by social memory deficits or coat state deterioration. However, coat state deterioration was consistent in 3xTg males. We report consistent heightened stress-induced corticosterone levels and Aβ pathology in female 3xTg-AD mice. However, the behavioral findings illuminate unknown inconsistencies in certain phenotypes in this AD mouse model.