Understanding the neuronal synapse and challenges associated with the mitochondrial dysfunction in mild cognitive impairment and Alzheimer's disease

Astrocytic HSP60 Deletion Induced Astrocyte Senescence and Inhibited Neuroregeneration via Modulating the S1P/Truncated-BDNF Pathway

Heat Shock Protein 60 (HSP60) plays a critical role in maintaining mitochondrial function in astrocytes and has a significant impact on central nervous system (CNS) health. However, how HSP60 regulates the mitochondrial function of astrocytes to inhibit neuroregeneration remains unknown. In this study, we generated astrocyte-specific HSP60 knockout male mice to investigate the consequences of HSP60 deficiency. Firstly, our results confirmed that HSP60 deficiency caused abnormal expression of mitochondrial function-related genes, causing significant mitochondrial dysfunction, which triggered cellular senescence in astrocytes. Moreover, the alterations of 5-hydroxytryptamine 2A receptor (5-HT2AR), glucocorticoid receptor (GR), dopamine D2 receptor (D2R), and N-methyl-D-aspartate receptor subunit 2A (NR2A) expression suggested a disruption in neurotransmission and synaptic plasticity. Additionally, the increased levels of site-1 protease (S1P), truncated brain-derived neurotrophic factor (truncated-BDNF), and synaptophysin indicate synaptic structural and functional impairments. Expectedly, our findings demonstrated mitochondrial dysfunction and cellular senescence in astrocytes, leading to altered expression of neurotransmitter receptors in the cortex, as well as reduced neuronal numbers and neurotransmitter levels in the hippocampus after the deletion of HSP60 in astrocytes of the male mice. Notably, Urolithin A (UA) and the S1P inhibitor, PF429242, were found to alleviate astrocyte senescence and promote neuronal regeneration by inhibiting truncated BDNF expression. In conclusion, our study revealed that HSP60 deficiency in astrocytes induces mitochondrial dysfunction and cellular senescence via the S1P/truncated-BDNF pathway, resulting in disrupted neurotransmitter receptor expression, synaptic protein alterations, and impaired neuroregeneration. These insights underscored the importance of HSP60 in CNS health and provided promising avenues for developing treatments for neurodegenerative disorders.

Investigating the neuroprotective effects of polyunsaturated fatty acids in egg yolk phospholipids upon oxidative damage in HT22 cells

Egg yolk phospholipids are primarily composed of various fatty acids, lysophosphatidylcholine and lysophosphatidylethanolamine. Existing studies have revealed the neuroprotective activity of egg yolk phospholipids. However, it is not clear which digestion products of phospholipids exert neuroprotective activity. The objective of this study was to investigate the neuroprotective effects of different structural components in egg yolk phospholipids based on a DMNQ-induced oxidative damage in HT22 cells. The findings demonstrated that pre-treatment with diverse egg yolk phospholipid components, particularly the polyunsaturated fatty acids, markedly elevated the cell viability and superoxide dismutase activity, diminished the ROS generation, reduced the malondialdehyde levels and elevated the mitochondrial membrane potential. Furthermore, RNA-Seq analysis demonstrated that unsaturated fatty acids exert its neuroprotective effects by upregulating the genes involved in cell proliferation (Jag2 and Ypel3), nervous system development (Ntf5), DNA damage repair (H2ax), and other related processes. These findings provide a theoretical basis for future studies on the characteristic structure of egg yolk phospholipids with profound neuroprotective effects.

Identification of NDUFV2, NDUFS7, OPA1, and NDUFA1 as biomarkers for Alzheimer's disease: Insights from oxidative stress and mitochondrial dysfunction in the hippocampus

BackgroundAlzheimer's disease (AD) is characterized by amyloid-β deposits, neurofibrillary tangles, and hippocampal neurodegeneration, with oxidative stress and mitochondrial dysfunction playing critical roles in its pathogenesis. Identifying hub genes associated with these processes could advance biomarker discovery and therapeutic strategies.ObjectiveThis study aimed to identify key oxidative stress- and mitochondrial dysfunction-related genes in the AD hippocampus, evaluate their diagnostic potential, and explore therapeutic agents targeting these genes.MethodsWe analyzed datasets GSE48350 and GSE5281, encompassing 56 controls and 29 AD patients. Weighted gene co-expression network analysis (WGCNA) selected genes with significance (adjusted p-value < 0.05 and |logFC| ≥ 0.5). Further studies involved immune cell infiltration, Gene set enrichment analysis (GSEA), and intersecting differentially expressed genes (DEGs) with oxidative stress-related genes (ORGs) and mitochondrial dysfunction-related genes (MDRGs). Functional enrichment and Protein-protein interaction (PPI) analyses were conducted. Experimental validation was done in AD mouse models, and diagnostic potential was tested using datasets GSE28146 and GSE29652. Therapeutic drugs were predicted based on hub genes.ResultsAD showed altered immune cell expression. GSEA linked DEGs to nervous system processes and neurotransmitters. 194 oxidative stress-related DEGs were enriched in neuronal death and mitochondrial processes. PPI analysis identified 24 DEGs related to both oxidative stress and mitochondrial dysfunction (DEO-MDRGs), with diagnostic potential (AUC > 0.5). LASSO regression selected four DEO-MDRGs: NDUFV2, NDUFS7, OPA1, and NDUFA1. Their protein levels were reduced in AD mice with decreased mitochondrial function. These genes showed good diagnostic performance. Potential drugs, like ME-344 and metformin hydrochloride, may be useful in AD treatment.ConclusionsNDUFV2, NDUFS7, OPA1, and NDUFA1 can serve as biomarkers for AD diagnosis.

The neuroimmune nexus: unraveling the role of the mtDNA-cGAS-STING signal pathway in Alzheimer's disease

The relationship between Alzheimer's disease (AD) and neuroimmunity has gradually begun to be unveiled. Emerging evidence indicates that cyclic GMP-AMP synthase (cGAS) acts as a cytosolic DNA sensor, recognizing cytosolic damage-associated molecular patterns (DAMPs), and inducing the innate immune response by activating stimulator of interferon genes (STING). Dysregulation of this pathway culminates in AD-related neuroinflammation and neurodegeneration. A substantial body of evidence indicates that mitochondria are involved in the critical pathogenic mechanisms of AD, whose damage leads to the release of mitochondrial DNA (mtDNA) into the extramitochondrial space. This leaked mtDNA serves as a DAMP, activating various pattern recognition receptors and immune defense networks in the brain, including the cGAS-STING pathway, ultimately leading to an imbalance in immune homeostasis. Therefore, modulation of the mtDNA-cGAS-STING pathway to restore neuroimmune homeostasis may offer promising prospects for improving AD treatment outcomes. In this review, we focus on the mechanisms of mtDNA release during stress and the activation of the cGAS-STING pathway. Additionally, we delve into the research progress on this pathway in AD, and further discuss the primary directions and potential hurdles in developing targeted therapeutic drugs, to gain a deeper understanding of the pathogenesis of AD and provide new approaches for its therapy.

Qiangji decoction mitigates neuronal damage, synaptic and mitochondrial dysfunction in SAMP8 mice through the regulation of ROCK2/Drp1-mediated mitochondrial dynamics

ETHNOPHARMACOLOGICAL RELEVANCE

Qiangji Decoction (QJD), a Chinese medicine, is widely used in Traditional Chinese Medicine to treat amnesia and Alzheimer's disease (AD), showing significant anti-AD effects. However, the precise mechanisms behind these effects are not well understood and require more research.

AIM OF THE STUDY

This study aims to elucidate the mechanisms by which QJD ameliorates neuronal damage, synaptic dysfunction, and mitochondrial impairment in AD through the regulation of ROCK2/Drp1-mediated mitochondrial dynamics.

MATERIALS AND METHODS

UPLC-Q-TOF-MS/MS was used to identify active components in QJD extract. The study used SAMP8 mice for AD modeling and SAMR1 mice as controls. Cognitive function in SAMP8 mice was assessed with the Morris Water Maze after following treatment with QJD and the mitochondrial fission inhibitor Mdivi-1. Nissl and FJB staining evaluated QJD's effect on hippocampal injury. Synaptic integrity was examined with Golgi-Cox staining, transmission electron microscopy, and immunofluorescence. Mitochondrial function in hippocampal neurons was assessed using electron microscopy, JC-1 staining, and reagent kits. Western blot analyzed expression of proteins related to mitochondrial fission (ROCK2, Drp1, Fis1, Mff) and fusion (Mfn1, Mfn2, OPA1).

RESULTS

The analysis of QJD extract via UPLC-Q-TOF-MS/MS led to the identification of 46 active compounds. In SAMP8 mice, administration of QJD resulted in decreased escape latency, increased platform crossings, and extended duration in the target quadrant. Additionally, QJD exhibited neuroprotective effects on the hippocampus of SAMP8 mice, effectively preventing neuronal loss and damage. QJD also facilitated the extension and thickening of dendritic spines, enhanced the ultrastructure of hippocampal synapses, and upregulated synaptic function-related proteins, including PSD95 and SYN1. Furthermore, QJD ameliorated mitochondrial damage, improved mitochondrial membrane potential and ATP content, and reduced ROS expression in hippocampal neurons of SAMP8 mice. These effects were mediated through the downregulation of ROCK2, phosphorylated Drp1 (Ser616), Fis1, and Mff, as well as the upregulation of Mfn1, Mfn2, and OPA1.

CONCLUSIONS

QJD may reduce neuronal damage, synaptic dysfunction, and mitochondrial impairment in SAMP8 mice by regulating mitochondrial dynamics through the ROCK2/Drp1 pathway.

Synaptic Vesicle-Related Proteins and Ubiquilin 2 in Cortical Synaptosomes Mediate Cognitive Impairment in Vascular Dementia Rats

Synaptic dysfunction is considered the best neuropathological correlate of cognitive decline in vascular dementia (VaD). However, the alterations of synaptic proteins at the synaptosomal level in VaD remain unclear. In this study, a VaD model was established in male rats using bilateral common carotid artery occlusion (2VO). We performed a novel object recognition task to evaluate cognitive impairment. Immunohistochemistry was used to assess the expression of neuron-specific nuclear binding protein (NeuN). Brain synaptosomes were isolated and subjected to label-free proteomic analysis to quantify and identify the synaptic features of differentially expressed proteins (DEPs). Synaptic and hub protein expression was detected in synaptosomes using western blotting. We found that male rats with VaD presented impaired memory and decreased NeuN protein expression in the cortex. Synaptosome proteomic analysis revealed 604 DEPs, with 493 and 111 markedly downregulated and upregulated proteins, respectively. KEGG analysis and SynGO annotation revealed that the synaptic vesicle (SV) cycle may be a key signaling pathway in VaD. Hub protein analysis of the main nodes in the protein network identified UBQLN2 and SV-related proteins, including CLTC, SNAP91, AP2S1, CLTA, VAMP2, EPN1, UBQLN2, AP2B1, AP2A2, and AP2M1. Western blotting showed that the levels of SV2A, CLTC, AP2S1, and VAMP2 decreased in the synaptosomes of 2VO rats, while UBQLN2 expression significantly increased. Our results suggest that the disruption in the presynaptic SV cycle is a key event in male rats with VaD, which could be characterized by the aberrant SV2A expression. SV-related proteins and UBQLN2 may be essential in synaptopathy. Thus, targeting the specific molecular markers in synaptosomes may be critical for the development of mechanism-directed therapies against VaD.

Early Synapse-Specific Alterations of Photoreceptor Mitochondria in the EAE Mouse Model of Multiple Sclerosis

Multiple sclerosis (MS) is an inflammatory autoimmune disease of the central nervous system (CNS) linked to many neurological disabilities. The visual system is frequently impaired in MS. In previous studies, we observed early malfunctions of rod photoreceptor ribbon synapses in the EAE mouse model of MS that included alterations in synaptic vesicle cycling and disturbances of presynaptic Ca2+ homeostasis. Since these presynaptic events are highly energy-demanding, we analyzed whether synaptic mitochondria, which play a major role in synaptic energy metabolism, might be involved at that early stage. Rod photoreceptor presynaptic terminals contain a single large mitochondrion next to the synaptic ribbon. In the present study, we analyzed the expression of functionally relevant mitochondrial proteins (MIC60, ATP5B, COX1, PINK1, DRP1) by high-resolution qualitative and quantitative immunofluorescence microscopy, immunogold electron microscopy and quantitative Western blot experiments. We observed a decreased expression of many functionally relevant proteins in the synaptic mitochondria of EAE photoreceptors at an early stage, suggesting that early mitochondrial dysfunctions play an important role in the early synapse pathology. Interestingly, mitochondria in presynaptic photoreceptor terminals were strongly compromised in early EAE, whereas extra-synaptic mitochondria in photoreceptor inner segments remained unchanged, demonstrating a functional heterogeneity of photoreceptor mitochondria.

Mitochondria and its epigenetic dynamics: Insight into synaptic regulation and synaptopathies

Mitochondria, the cellular powerhouses, are pivotal to neuronal function and health, particularly through their role in regulating synaptic structure and function. Spine reprogramming, which underlies synapse development, depends heavily on mitochondrial dynamics-such as biogenesis, fission, fusion, and mitophagy as well as functions including ATP production, calcium (Ca2+) regulation, and retrograde signaling. Mitochondria supply the energy necessary for assisting synapse development and plasticity, while also regulating intracellular Ca2+ homeostasis to prevent excitotoxicity and support synaptic neurotransmission. Additionally, the dynamic processes of mitochondria ensure mitochondrial quality and adaptability, which are essential for maintaining effective synaptic activity. Emerging evidence highlights the significant role of epigenetic modifications in regulating mitochondrial dynamics and function. Epigenetic changes influence gene expression, which in turn affects mitochondrial activity, ensuring coordinated responses necessary for synapse development. Furthermore, metabolic changes within mitochondria can impact the epigenetic machinery, thereby modulating gene expression patterns that support synaptic integrity. Altered epigenetic regulation affecting mitochondrial dynamics and functions is linked to several neurological disorders, including Amyotrophic Lateral Sclerosis, Huntington's, Alzheimer's, and Parkinson's diseases, emphasizing its crucial function. The review delves into the molecular machinery involved in mitochondrial dynamics, ATP and Ca2+ regulation, highlighting the role of key proteins that facilitate the processes. Additionally, it also shed light on the emerging epigenetic factors influencing these regulations. It provides a thorough summary on the current understanding of the role of mitochondria in synapse development and emphasizes the importance of both molecular and epigenetic mechanisms in maintaining synaptic integrity.

Mitochondrial Dysfunction and Cognitive Impairment in Schizophrenia: The Role of Inflammation

BACKGROUND AND HYPOTHESIS

The complex immune-brain interactions and the regulatory role of mitochondria in the immune response suggest that mitochondrial damage reported in schizophrenia (SZ) may be related to abnormalities observed in immune and brain functions.

STUDY DESIGN

Mitochondrial DNA copy number (mtDNA CN), a biomarker of mitochondrial function, was assessed in peripheral blood leukocytes (PBLs) of 121 healthy individuals and 118 SZ patients before and after 8 weeks of antipsychotic treatment, and a meta-analysis related to blood mtDNA CN was conducted. Plasma C-reactive protein (CRP) levels in SZ patients were obtained from the medical record system. Spearman correlation analysis and hierarchical linear regression were used to analyze the relationships among mtDNA CN, CRP levels, and cognitive function. A mediation model was constructed using the PROCESS program.

STUDY RESULTS

Our results revealed the decreased mtDNA CN in PBLs from SZ patients (P = .05). The meta-analysis supported the decreased blood mtDNA CN in SZ patients (P < .01). The mtDNA CN in PBL was positively correlated with working memory (P = .02) and negatively correlated with plasma CRP levels (P = .039). Furthermore, a lower mtDNA CN in PBL in SZ patients was a significant predictor of worse working memory (P = .006). CRP acted as a mediator with an 8.0% effect.

CONCLUSIONS

This study revealed an association between peripheral mitochondrial dysfunction and cognitive impairment in SZ, with inflammation acting as a mediating effect. Therefore, mitochondrial dysfunction might provide novel targets for new treatments for cognitive impairment in SZ.

Functional Relationships between L1CAM, LC3, ATG12, and Aβ

Abnormal protein accumulations in the brain are linked to aging and the pathogenesis of dementia of various types, including Alzheimer's disease. These accumulations can be reduced by cell indigenous mechanisms. Among these is autophagy, whereby proteins are transferred to lysosomes for degradation. Autophagic dysfunction hampers the elimination of pathogenic protein aggregations that contribute to cell death. We had observed that the adhesion molecule L1 interacts with microtubule-associated protein 1 light-chain 3 (LC3), which is needed for autophagy substrate selection. L1 increases cell survival in an LC3-dependent manner via its extracellular LC3 interacting region (LIR). L1 also interacts with Aβ and reduces the Aβ plaque load in an AD model mouse. Based on these results, we investigated whether L1 could contribute to autophagy of aggregated Aβ and its clearance. We here show that L1 interacts with autophagy-related protein 12 (ATG12) via its LIR domain, whereas interaction with ubiquitin-binding protein p62/SQSTM1 does not depend on LIR. Aβ, bound to L1, is carried to the autophagosome leading to Aβ elimination. Showing that the mitophagy-related L1-70 fragment is ubiquitinated, we expect that the p62/SQSTM1 pathway also contributes to Aβ elimination. We propose that enhancing L1 functions may contribute to therapy in humans.

Neurobehavioral dysfunction in a mouse model of Down syndrome: upregulation of cystathionine β-synthase, H2S overproduction, altered protein persulfidation, synaptic dysfunction, endoplasmic reticulum stress, and autophagy

Down syndrome (DS) is a genetic condition where the person is born with an extra chromosome 21. DS is associated with accelerated aging; people with DS are prone to age-related neurological conditions including an early-onset Alzheimer's disease. Using the Dp(17)3Yey/ + mice, which overexpresses a portion of mouse chromosome 17, which encodes for the transsulfuration enzyme cystathionine β-synthase (CBS), we investigated the functional role of the CBS/hydrogen sulfide (H2S) pathway in the pathogenesis of neurobehavioral dysfunction in DS. The data demonstrate that CBS is higher in the brain of the DS mice than in the brain of wild-type mice, with primary localization in astrocytes. DS mice exhibited impaired recognition memory and spatial learning, loss of synaptosomal function, endoplasmic reticulum stress, and autophagy. Treatment of mice with aminooxyacetate, a prototypical CBS inhibitor, improved neurobehavioral function, reduced the degree of reactive gliosis in the DS brain, increased the ability of the synaptosomes to generate ATP, and reduced endoplasmic reticulum stress. H2S levels in the brain of DS mice were higher than in wild-type mice, but, unexpectedly, protein persulfidation was decreased. Many of the above alterations were more pronounced in the female DS mice. There was a significant dysregulation of metabolism in the brain of DS mice, which affected amino acid, carbohydrate, lipid, endocannabinoid, and nucleotide metabolites; some of these alterations were reversed by treatment of the mice with the CBS inhibitor. Thus, the CBS/H2S pathway contributes to the pathogenesis of neurological dysfunction in DS in the current animal model.

Role of Cytoskeletal Elements in Regulation of Synaptic Functions: Implications Toward Alzheimer's Disease and Phytochemicals-Based Interventions

Alzheimer's disease (AD), a multifactorial disease, is characterized by the accumulation of neurofibrillary tangles (NFTs) and amyloid beta (Aβ) plaques. AD is triggered via several factors like alteration in cytoskeletal proteins, a mutation in presenilin 1 (PSEN1), presenilin 2 (PSEN2), amyloid precursor protein (APP), and post-translational modifications (PTMs) in the cytoskeletal elements. Owing to the major structural and functional role of cytoskeletal elements, like the organization of axon initial segmentation, dendritic spines, synaptic regulation, and delivery of cargo at the synapse; modulation of these elements plays an important role in AD pathogenesis; like Tau is a microtubule-associated protein that stabilizes the microtubules, and it also causes inhibition of nucleo-cytoplasmic transportation by disrupting the integrity of nuclear pore complex. One of the major cytoskeletal elements, actin and its dynamics, regulate the dendritic spine structure and functions; impairments have been documented towards learning and memory defects. The second major constituent of these cytoskeletal elements, microtubules, are necessary for the delivery of the cargo, like ion channels and receptors at the synaptic membranes, whereas actin-binding protein, i.e., Cofilin's activation form rod-like structures, is involved in the formation of paired helical filaments (PHFs) observed in AD. Also, the glial cells rely on their cytoskeleton to maintain synaptic functionality. Thus, making cytoskeletal elements and their regulation in synaptic structure and function as an important aspect to be focused for better management and targeting AD pathology. This review advocates exploring phytochemicals and Ayurvedic plant extracts against AD by elucidating their neuroprotective mechanisms involving cytoskeletal modulation and enhancing synaptic plasticity. However, challenges include their limited bioavailability due to the poor solubility and the limited potential to cross the blood-brain barrier (BBB), emphasizing the need for targeted strategies to improve therapeutic efficacy.

Mechanism and therapeutic targets of the involvement of a novel lysosomal proton channel TMEM175 in Parkinson's disease

Parkinson's disease (PD), recognized as the second most prevalent neurodegenerative disease in the aging population, presents a significant challenge due to the current lack of effective treatment methods to mitigate its progression. Many pathogenesis of PD are related to lysosomal dysfunction. Moreover, extensive genetic studies have shown a significant correlation between the lysosomal membrane protein TMEM175 and the risk of developing PD. Building on this discovery, TMEM175 has been identified as a novel potassium ion channel. Intriguingly, further investigations have found that potassium ion channels gradually close and transform into hydrion "excretion" channels in the microenvironment of lysosomes. This finding was further substantiated by studies on TMEM175 knockout mice, which exhibited pronounced motor dysfunction in pole climbing and suspension tests, alongside a notable reduction in dopamine neurons within the substantia nigra compacta. Despite these advancements, the current research landscape is not without its controversies. In light of this, the present review endeavors to methodically examine and consolidate a vast array of recent literature on TMEM175. This comprehensive analysis spans from the foundational research on the structure and function of TMEM175 to expansive population genetics studies and mechanism research utilizing cellular and animal models.A thorough understanding of the structure and function of TMEM175, coupled with insights into the intricate mechanisms underpinning lysosomal dysfunction in PD dopaminergic neurons, is imperative. Such knowledge is crucial for pinpointing precise intervention targets, thereby paving the way for novel therapeutic strategies that could potentially alter the neurodegenerative trajectory of PD.

Harnessing nanomedicine for modulating microglial states in the central nervous system disorders: Challenges and opportunities

Microglia are essential for maintaining homeostasis and responding to pathological events in the central nervous system (CNS). Their dynamic and multidimensional states in different environments are pivotal factors in various CNS disorders. However, therapeutic modulation of microglial states is challenging due to the intricate balance these cells maintain in the CNS environment and the blood-brain barrier's restriction of drug delivery. Nanomedicine presents a promising avenue for addressing these challenges, offering a method for the targeted and efficient modulation of microglial states. This review covers the challenges faced in microglial therapeutic modulation and potential use of nanoparticle-based drug delivery systems. We provide an in-depth examination of nanoparticle applications for modulating microglial states in a range of CNS disorders, encompassing neurodegenerative and autoimmune diseases, infections, traumatic injuries, stroke, tumors, chronic pain, and psychiatric conditions. This review highlights the recent advancements and future prospects in nanomedicine for microglial modulation, paving the way for future research and clinical applications of therapeutic interventions in CNS disorders.

Neuronal A2A receptor exacerbates synapse loss and memory deficits in APP/PS1 mice

Early pathological upregulation of adenosine A2A receptors (A2ARs), one of the caffeine targets, by neurons is thought to be involved in the development of synaptic and memory deficits in Alzheimer's disease (AD) but mechanisms remain ill-defined. To tackle this question, we promoted a neuronal upregulation of A2AR in the hippocampus of APP/PS1 mice developing AD-like amyloidogenesis. Our findings revealed that the early upregulation of A2AR in the presence of an ongoing amyloid pathology exacerbates memory impairments of APP/PS1 mice. These behavioural changes were not linked to major change in the development of amyloid pathology but rather associated with increased phosphorylated tau at neuritic plaques. Moreover, proteomic and transcriptomic analyses coupled with quantitative immunofluorescence studies indicated that neuronal upregulation of the receptor promoted both neuronal and non-neuronal autonomous alterations, i.e. enhanced neuroinflammatory response but also loss of excitatory synapses and impaired neuronal mitochondrial function, presumably accounting for the detrimental effect on memory. Overall, our results provide compelling evidence that neuronal A2AR dysfunction, as seen in the brain of patients, contributes to amyloid-related pathogenesis and underscores the potential of A2AR as a relevant therapeutic target for mitigating cognitive impairments in this neurodegenerative disorder.

Investigating hormesis, aging, and neurodegeneration: From bench to clinics

Mitochondria-derived reactive oxygen species production at a moderate physiological level plays a fundamental role in the anti-aging signaling, due to their action as redox-active sensors for the maintenance of optimal mitochondrial balance between intracellular energy status and hormetic nutrients. Iron regulatory protein dysregulation, systematically increased iron levels, mitochondrial dysfunction, and the consequent oxidative stress are recognized to underlie the pathogenesis of multiple neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease. Central to their pathogenesis, Nrf2 signaling dysfunction occurs with disruption of metabolic homeostasis. We highlight the potential therapeutic importance of nutritional polyphenols as substantive regulators of the Nrf2 pathway. Here, we discuss the common mechanisms targeting the Nrf2/vitagene pathway, as novel therapeutic strategies to minimize consequences of oxidative stress and neuroinflammation, generally associated to cognitive dysfunction, and demonstrate its key neuroprotective and anti-neuroinflammatory properties, summarizing pharmacotherapeutic aspects relevant to brain pathophysiology.

Connecting the dots: the role of fatigue in female infertility

Fatigue, an increasingly acknowledged symptom in various chronic diseases, has garnered heightened attention, during the medical era of bio-psycho-social model. Its persistence not only significantly compromises an individual's quality of life but also correlates with chronic organ damage. Surprisingly, the intricate relationship between fatigue and female reproductive health, specifically infertility, remains largely unexplored. Our exploration into the existing body of evidence establishes a compelling link between fatigue with uterine and ovarian diseases, as well as conditions associated with infertility, such as rheumatism. This observation suggests a potentially pivotal role of fatigue in influencing overall female fertility. Furthermore, we propose a hypothetical mechanism elucidating the impact of fatigue on infertility from multiple perspectives, postulating that neuroendocrine, neurotransmitter, inflammatory immune, and mitochondrial dysfunction resulting from fatigue and its co-factors may further contribute to endocrine disorders, menstrual irregularities, and sexual dysfunction, ultimately leading to infertility. In addition to providing this comprehensive theoretical framework, we summarize anti-fatigue strategies and accentuate current knowledge gaps. By doing so, our aim is to offer novel insights, stimulate further research, and advance our understanding of the crucial interplay between fatigue and female reproductive health.

Dihydropashanone Isolated from Lindera erythrocarpa, a Potential Natural Product for the Treatment of Neurodegenerative Diseases

Lindera erythrocarpa, a flowering plant native to eastern Asia, has been reported to have neuroprotective activity. However, reports on the specific bioactive compounds in L. erythrocarpa are finite. The aim of this study was to investigate the anti-neuroinflammatory and neuroprotective effects of the compounds isolated from L. erythrocarpa. Dihydropashanone, a compound isolated from L. erythrocarpa extract, was found to have protected mouse hippocampus HT22 cells from glutamate-induced cell death. The antioxidant and anti-inflammatory properties of dihydropashanone in mouse microglial BV2 and HT22 cells were explored in this study. The results reveal that dihydropashanone inhibits lipopolysaccharide-induced inflammatory response and suppresses the activation of nuclear factor (NF)-κB in BV2 cells. In addition, dihydropashanone reduced the buildup of reactive oxygen species in HT22 cells and induced activation of the nuclear factor E2-related factor 2 (Nrf2)/heme oxygenase (HO)-1 signaling pathway in BV2 and HT22 cells. Our results suggest that dihydropashanone reduces neuroinflammation by decreasing NF-κB activation in microglia cells and protects neurons from oxidative stress via the activation of the Nrf2/HO-1 pathway. Thus, our data suggest that dihydropashanone offers a broad range of applications in the treatment of neurodegenerative illnesses.

Examining the Role of a Functional Deficiency of Iron in Lysosomal Storage Disorders with Translational Relevance to Alzheimer's Disease

The recently presented Azalea Hypothesis for Alzheimer's disease asserts that iron becomes sequestered, leading to a functional iron deficiency that contributes to neurodegeneration. Iron sequestration can occur by iron being bound to protein aggregates, such as amyloid β and tau, iron-rich structures not undergoing recycling (e.g., due to disrupted ferritinophagy and impaired mitophagy), and diminished delivery of iron from the lysosome to the cytosol. Reduced iron availability for biochemical reactions causes cells to respond to acquire additional iron, resulting in an elevation in the total iron level within affected brain regions. As the amount of unavailable iron increases, the level of available iron decreases until eventually it is unable to meet cellular demands, which leads to a functional iron deficiency. Normally, the lysosome plays an integral role in cellular iron homeostasis by facilitating both the delivery of iron to the cytosol (e.g., after endocytosis of the iron-transferrin-transferrin receptor complex) and the cellular recycling of iron. During a lysosomal storage disorder, an enzyme deficiency causes undigested substrates to accumulate, causing a sequelae of pathogenic events that may include cellular iron dyshomeostasis. Thus, a functional deficiency of iron may be a pathogenic mechanism occurring within several lysosomal storage diseases and Alzheimer's disease.