Hippocampal neurogenesis: Learning to remember

Ouabain increases neuronal differentiation of hippocampal neural precursor cells

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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.

EPRCN exerts neuroprotective function by regulating gut microbiota and restoring gut immune homeostasis in Alzheimer's disease model mice

BackgroundNo effective drug treatment is currently available for Alzheimer's disease (AD), highlighting the urgent need to develop efficient therapeutic options. We have developed a formula based on medicine and food homology (MFH) consisting of egg yolk oil, perilla seed oil, raphani seed oil, cinnamon oil, and noni puree (EPRCN), and demonstrated that it can treat AD by alleviating neuroinflammation and oxidative stress. However, whether EPRCN can improve AD by regulating gut microbiota remains unknown.ObjectiveThe current study aimed to evaluate the effect of EPRCN on regulating gut microbiota and neuroprotection.Methods16S rRNA sequencing was used to assess the structure of gut microbiota. Hematoxylin-eosin (HE) staining, qRT-PCR, and ELISA were used to evaluate gut inflammation. Detected indexes associated with cholinergic dysfunction and neuronal damage to investigate the neuroprotective effects of EPRCN.Results16S rRNA gene analysis revealed that EPRCN remodeled the gut microbiota, inhibited gut metabolic disorders, and promoted CoA biosynthesis in scopolamine-induced mice. EPRCN can ameliorates gut inflammation by activating the cholinergic anti-inflammatory pathway. The results further indicated that EPRCN improved cholinergic dysfunction by inhibiting the activity of acetylcholinesterase and restoring cholinergic receptors. Additionally, EPRCN administration suppressed the neuronal loss and elevated brain derived neurotrophic factor expression in hippocampus. Correlation analysis found that alteration of several gut microbes was associated with indexes improved by EPRCN.ConclusionsThese findings suggest that EPRCN may serve as a promising dietary intervention for treating AD by regulating the microbiota-gut-brain axis and exerting neuroprotective function.

Controversies and insights into cytokine regulation of neurogenesis and behavior in adult rodents

Adult learning, memory, and social interaction partially depend on neurogenesis in two regions: the hippocampus and the subventricular zone. There is evidence that the immune system is important for these processes in pathological situations, but there is no review of its role in non-pathological or near-physiological conditions. Although further research is warranted in this area, some conclusions can be drawn. Intrusive LyC6hi monocytes and autoreactive CD4+ T cells have a positive impact on neurogenesis and behavior, but the latter are deleterious if specific to external antigens. Mildly activated microglia play a crucial role in promoting these processes, by eliminating apoptotic neuronal progenitors and producing low levels of interleukins, which increase if the cells are activated, leading to inhibition of neurogenesis. Chemokines are poorly studied, but progenitor cells and neurons express their receptors, which appear important for migration and maturation. The few works that jointly analyzed neurogenesis and behavior showed congruent effects of immune cells and cytokines. In conclusion, the immune system components -mostly local- seem of utmost importance for the control of behavior under non-pathological conditions.

Neurogenesis drives hippocampal formation-wide spatial transcription alterations in health and Alzheimer's disease

The mechanism by which neurogenesis regulates the profile of neurons and glia in the hippocampal formation is not known. Further, the effect of neurogenesis on neuronal vulnerability characterizing the entorhinal cortex in Alzheimer's disease (AD) is unknown. Here, we used in situ sequencing to investigate the spatial transcription profile of neurons and glia in the hippocampal circuitry in wild-type mice and in familial AD (FAD) mice expressing varying levels of neurogenesis. This approach revealed that in addition to the dentate gyrus, neurogenesis modulates the cellular profile in the entorhinal cortex and CA regions of the hippocampus. Notably, enhancing neurogenesis in FAD mice led to partial restoration of neuronal and cellular profile in these brain areas, resembling the profile of their wild-type counterparts. This approach provides a platform for the examination of the cellular dynamics in the hippocampal formation in health and in AD.

Obstructive sleep apnea and memory impairments: Clinical characterization, treatment strategies, and mechanisms

Obstructive sleep apnea (OSA), is associated with dysfunction in the cardiovascular, metabolic and neurological systems. However, the relationship between OSA and memory impairment, intervention effects, and underlying pathways are not well understood. This review summarizes recent advances in the clinical characterization, treatment strategies, and mechanisms of OSA-induced memory impairments. OSA patients may exhibit significant memory declines, including impairments in working memory from visual and verbal sources. The underlying mechanisms behind OSA-related memory impairment are complex and multifactorial with poorly understood aspects that require further investigation. Neuroinflammation, oxidative stress, neuronal damage, synaptic plasticity, and blood-brain barrier dysfunction, as observed under exposures to intermittent hypoxia and sleep fragmentation are likely contributors to learning and memory dysfunction. Continuous positive airway pressure treatment can provide remarkable relief from memory impairment in OSA patients. Other treatments are emerging but need to be rigorously evaluated for cognitive improvement. Clinically, reliable and objective diagnostic tools are necessary for accurate diagnosis and clinical characterization of cognitive impairments in OSA patients. The complex links between gut-brain axis, epigenetic landscape, genetic susceptibility, and OSA-induced memory impairments suggest new directions for research. Characterization of clinical phenotypic clusters can facilitate advances in precision medicine to predict and treat OSA-related memory deficits.

Investigation of Tongqiao Huashuan Granules' effect on hippocampal neuron autophagy in vascular dementia rats via the PI3K/Akt-mTOR signaling pathway using network pharmacology and experimental validation

Objective

This study aimed to apply network pharmacology to identify the active components and key targets of Tongqiao Huashuan Granules in vascular dementia (VaD) and to evaluate its effects on autophagy in hippocampal neurons of VaD rats through animal testing.

Materials and methods

This study first employed network pharmacology (NP) to identify potential components and pathway targets for THg intervention in VaD. A modified two-vessel occlusion (2-VO) method was subsequently analyzed to establish a VaD rat model. Following the interventions, the spatial learning and memory abilities of the rats were assess using a water maze experiment. Morphological and structural changes in neuronal cells within the CA1 region of the rat hippocampus were examined using hematoxylin and eosin (HE) staining. Immunohistochemistry was utilized to assess the proportions of Beclin1-positive and LC3-positive cells in the CA1 region of each rat group, while performed Western blot analysis was conducted to measure protein expression levels of PI3K, p-PI3K, AKT, p-AKT, mTOR, p-mTOR, Beclin1, and LC3 in the hippocampal tissue of the rats.

Results

A total of 76 active components were identified through network pharmacology analysis, with notable components including β-sitosterol, kaempferol, and cinnamophilin. In total, 825 key targets were identified, including IL1B, AKT1, JAK1, and MAPK3. THg and VaD shared 69 common genes. The Gene Ontology (GO) functional enrichment analysis yielded a total of 569 items (BP: 366, CC: 97, MF: 106). KEGG pathway enrichment analysis identified 143 signaling pathways, including TNF, MAPK, AGE-RAGE, and PI3K/Akt pathways. Subsequent validation experiments demonstrated that THg enhanced the learning and memory abilities of VaD rats, improve the morphology of neuronal cells in the CA1 region of the hippocampus, and decreasing the proportion of Beclin1-and LC3-positive cells in this region. Additionally, THg was shown to enhance the expression levels of p-PI3K, p-AKT, and p-mTOR proteins while reducing the expression levels of Beclin1 and LC3 proteins.

Conclusion

This study represents the first investigation into the effects of THg intervention in VaD, indicating that its mechanism may involve inhibiting autophagy in hippocampal neurons through activation of the PI3K/Akt-mTOR signaling pathway.

Central Med23 deficiency leads to malformation of dentate gyrus and ADHD-like behaviors in mice

Attention-deficit hyperactivity disorder (ADHD) is a prevalent psychiatric disorder with high heritability, while its etiology and pathophysiology remain unclear. Med23 is a subunit of the Mediator complex, a key regulator of gene expression by linking transcription factors to RNA polymerase II. The mutations of Med23 are associated with several brain diseases including microcephaly, epilepsy and intellectual disability, but its biological roles in brain development and possible behavioral consequence have not been explored in the animal model. In this study, Emx1-Cre mice were used to generate Med23 conditional knockout (Med23 CKO) mice that showed severe hypoplasia of the dentate gyrus (DG) with malformation of the dendritic tree and spines along with impaired short-term synaptic plasticity. Interestingly, Med23 CKO mice exhibited ADHD-like behaviors as shown by hyperactivity, inattention and impulsivity, as well as impaired sensory gating and working memory. Importantly, methylphenidate (MPH), a common drug for ADHD ameliorated these deficits in the CKO mice. Furthermore, we also revealed that the impaired synaptic plasticity was partially restored by MPH in an N-methyl-d-aspartate (NMDA) receptor-dependent way. Collectively, our data demonstrate Med23 deficiency causes DG malformation and ADHD-like behaviors, suggesting a novel mechanism underlying relevant brain diseases.

Significance of the gut tract in the therapeutic mechanisms of polydopamine for acute cerebral infarction: neuro-immune interaction through the gut-brain axis

Background

Recent research has made significant progress in elucidating gastrointestinal complications following acute cerebral infarction (ACI), which includes disorders in intestinal motility and dysbiosis of the gut microbiota. Nevertheless, the role of the gut (which is acknowledged as being the largest immune organ) in the immunoreactive effects of polydopamine nanoparticles (PDA) on acute ischemic stroke remains inadequately understood. In addition to its function in nutrient absorption, the gut acts as a protective barrier against microbes. Systemic immune responses, which are triggered by the disruption of gut barrier integrity, are considered as one of the mechanisms underlying acute ischemic stroke, with the gut-brain axis (GBA) playing a pivotal role in this process.

Methods

In this study, we used a PDA intervention in an ACI model to investigate ACI-like behavior, intestinal barrier function, central and peripheral inflammation, and hippocampal neuron excitability, thus aiming to elucidate the mechanisms through which PDA improves ACI via the GBA.

Results

Our findings indicated that as ACI mice experienced dysbiosis of the gut microbiota and intestinal barrier damage, the levels of proinflammatory factors in the serum and brain significantly increased. Additionally, the activation of astrocytes in the hippocampal region and neuronal apoptosis were observed in ACI mice. Importantly, our study is the first to provide evidence demonstrating that PDA effectively suppresses the neuroimmune interactions of the gut-brain axis and significantly improves intestinal epithelial barrier integrity.

Conclusion

We hope that our discoveries will serve as a foundation for further explorations of the therapeutic mechanisms of PDA in ACI, particularly in elucidating the protective roles of gut microbiota and intestinal barrier function, as well as in the development of more targeted clinical interventions for ACI.

Anti-RGMa neutralizing antibody ameliorates vascular cognitive impairment in mice

Repulsive Guidance Molecule A (RGMa) is well-recognized for its role in axon guidance. Recent studies have unveiled its diverse functions under pathological conditions within the central nervous system, such as spinal cord injury, multiple sclerosis, and Parkinson's disease. In this study, we explored the involvement of RGMa and the therapeutic effects of an anti-RGMa neutralizing antibody in a mouse model of vascular dementia (VaD). The VaD mouse model was established using the bilateral common carotid artery stenosis (BCAS) method. Immunohistochemical analysis revealed that these mice exhibited increased RGMa expression in the hippocampus, which coincided with reduced neurogenesis and impaired cholinergic innervation. These alterations manifested as cognitive impairments in the BCAS mice. Significantly, treatment with anti-RGMa neutralizing antibody reversed these pathological changes and cognitive deficits. Our findings suggest that RGMa plays a pivotal role in VaD pathology within the hippocampus and propose the anti-RGMa antibody as a promising therapeutic avenue for treating VaD.

Reduced Functional Connectivity in Nucleus Accumbens Subregions Associates With Cognitive Changes in Alzheimer's Disease

BACKGROUND AND PURPOSE

The nucleus accumbens (NAc), an important component of the reward circuit, is believed to play an indispensable role in Alzheimer's disease (AD). This study aimed to explore alterations in the functional connectivity (FC) of NAc subregions in AD patients and to explore their associations with neuropsychological profiles.

METHODS

Total 45 AD patients and 41 healthy controls (HCs) were recruited for this study. Four subregions of the NAc were used as regions of interest for whole-brain FC analysis. Correlation analyses were conducted to explore the relationships between the changed FC of brain regions with significant differences and neuropsychological profiles.

RESULTS

Compared with HCs, decreased FC was observed between NAc subregions and regions of the orbitofrontal cortex (OFC), precuneus (PCUN), insula (INS), cerebellum 8, and putamen in AD patients (Gaussian random field [GRF] corrected, voxel-level p < 0.001, cluster-level p < 0.05). Furthermore, the FC between the left core and left PCUN was correlated with the score of the auditory verbal learning test immediate recall task in AD patients (r = 0.441, p = 0.003, Bonferroni corrected).

CONCLUSION

Disruptions in connectivity between the NAc subregions and important cognitive-related areas may be related to the cognitive deficits observed in AD patients, especially episodic memory function.

Gut microbiota: A new window for the prevention and treatment of neuropsychiatric disease

Under normal physiological conditions, gut microbiota and host mutually coexist. They play key roles in maintaining intestinal barrier integrity, absorption, and metabolism, as well as promoting the development of the central nervous system (CNS) and emotional regulation. The dysregulation of gut microbiota homeostasis has attracted significant research interest, specifically in its impact on neurological and psychiatric disorders. Recent studies have highlighted the important role of the gut- brain axis in conditions including Alzheimer's Disease (AD), Parkinson's Disease (PD), and depression. This review aims to elucidate the regulatory mechanisms by which gut microbiota affect the progression of CNS disorders via the gut-brain axis. Additionally, we discuss the current research landscape, identify gaps, and propose future directions for microbial interventions against these diseases. Finally, we provide a theoretical reference for clinical treatment strategies and drug development for AD, PD, and depression.

Decreasing β-Catenin Leads to Altered Endothelial Morphology, Increased Barrier Permeability and Cognitive Impairment During Chronic Methamphetamine Exposure

Cognitive impairment induced by chronic methamphetamine (METH) exposure exhibits similarities to neurodegenerative disorders and is associated with blood-brain barrier (BBB) dysfunction. However, the potential involvement of β-catenin in maintaining BBB integrity during METH exposure remains unexplored. In this study, Y-maze and novel object recognition tests were conducted to assess cognitive impairment in mice exposed chronically to methamphetamine for 2 and 4 weeks. Gd-DTPA and Evans blue leakage tests revealed disruption of the BBB in the hippocampus, while chronic METH exposure for 2 and 4 weeks significantly decreased β-catenin levels along with its transcriptionally regulated protein, claudin5. Additionally, various neural injury-related proteins, such as APP, Aβ1-42, p-tau (Thr181) and p-tau (Ser396), as well as neuroinflammation-related proteins, such as IL-6, IL-1β, and TNF-α, exhibited increased levels following chronic METH exposure. Furthermore, plasma analysis indicated elevated levels of p-Tau (total), neurofilament light chain, and GFAP. In vitro experiments demonstrated that exposure to METH resulted in dose-dependent and time-dependent reductions in cellular activity and connectivity of bEnd.3 and hcmec/D3 cells. Furthermore, β-catenin exhibited decreased levels and altered subcellular localization, transitioning from the cell membrane to the cytoplasm and nucleus upon METH exposure. Overexpression of β-catenin was found to alleviate endothelial toxicity and attenuate junctional weakening induced by METH. The aforementioned findings underscore the crucial involvement of β-catenin in endothelial cells during chronic METH exposure-induced disruption of the BBB, thereby presenting a potential novel target for addressing METH-associated cerebrovascular dysfunction and cognitive impairment.

Protective Effect of Rosmarinic Acid on Endotoxin-Induced Neuronal Damage Through Modulating GRP78/PERK/MANF Pathway

Objective

Neuronal damage is criminal to cognitive dysfunction, closely related to endoplasmic reticulum stress (ERS). However, due to the pathogenesis of endotoxin-induced long-term cognitive dysfunction is not fully clarified, there is still a lack of effective treatment. This study was conducted to explore the protective effects and mechanism of rosmarinic acid (RA) against ERS in endotoxin-induced cognitive dysfunction in mice and neuronal injury in cells.

Methods

The efficacy of RA was evaluated using an endotoxin-induced cognitive dysfunction mice model and an in vitro neuronal injury model. Brain injury was assessed using behavioral tests and hematoxylin and eosin (HE) staining. Western blotting and Immunohistochemistry (IHC) were performed to determine NeuN, GRP78, PERK, ATF6, IRE1α, and MANF expression levels. Molecular docking was used to assess the associated mechanisms.

Results

Behavioral tests indicated that 20 and 40 mg/kg RA significantly improve endotoxin-induced cognitive dysfunction without dose differences. Histological analysis revealed no significant alterations in the number, morphology, and arrangement of neurons in the hippocampus and amygdala. However, 40 mg/kg RA treatment significantly decreased the hippocampal level of PERK protein and increased MANF in CA1 and DG in mice. Furthermore, our data showed that 120 μM RA pretreatment significantly inhibited LPS-conditioned culture-induced GRP78, PERK, and MANF upregulation in vitro. Finally, molecular docking studies suggested that RA could directly interact with GRP78, PERK, and IRE1, but not with MANF.

Conclusion

RA plays a protective role in improving cognitive function against endotoxemia-associated encephalopathy in mice via inhibiting the GRP78/PERK/MANF pathway.

Clinical-grade human dental pulp stem cells improve adult hippocampal neural regeneration and cognitive deficits in Alzheimer's disease

Background: Disrupted hippocampal functions and progressive neuronal loss represent significant challenges in the treatment of Alzheimer's disease (AD). How to achieve the improvement of pathological progression and effective neural regeneration to ameliorate the intracerebral dysfunctional environment and cognitive impairment is the goal of the current AD therapy. Methods: We examined the therapeutic potential of clinical-grade human derived dental pulp stem cells (hDPSCs) in cognitive function and neuropathology in AD. Specifically, we investigated the effect of neural crest-specific derived hDPSCs on endogenous neural regeneration and long-term efficacy following a single transplantation in the triple-transgenic mouse model (3xTg-AD). Results: Our research demonstrated that a single administration of clinical-grade hDPSCs yielded dramatic short-term therapeutic benefits (5 weeks) and sustained partial efficacy (6 months) with respect to improving cognitive impairment and delaying typical pathological progression in 3xTg-AD mice. Intriguingly, exogenous hDPSCs were robustly self-differentiated into newborn functional neurons in the hippocampus of 3xTg-AD mice. The foremost evidence is provided that hDPSCs promote endogenic neural regeneration by enhancing the activation of the Wnt/β-catenin pathway, which may contribute to stabilizing the hippocampal neural network to reverse memory deficits. Conclusion: These findings highlight the multifunctional potential of hDPSCs in AD treatment, which enhances cognition through alleviating neuropathology and providing neural regenerative driving force. Understanding these multiplicity effects is critical to advancing the clinical translation of stem cell-based therapies for AD.

The impact of aging on HIV-1-related neurocognitive impairment

Depending on the population studied, HIV-1-related neurocognitive impairment is estimated to impact up to half the population of people living with HIV (PLWH) despite the availability of combination antiretroviral therapy (cART). Various factors contribute to this neurocognitive impairment, which complicates our understanding of the molecular mechanisms involved. Biological aging has been implicated as one factor possibly impacting the development and progression of HIV-1-related neurocognitive impairment. This is increasingly important as the life expectancy of PLWH with virologic suppression on cART is currently projected to be similar to that of individuals not living with HIV. Based on our increasing understanding of the biological aging process on a cellular level, we aim to dissect possible interactions of aging- and HIV-1 infection-induced effects and their role in neurocognitive decline. Thus, we begin by providing a brief overview of the clinical aspects of HIV-1-related neurocognitive impairment and review the accumulating evidence implicating aging in its development (Part I). We then discuss potential interactions between aging-associated pathways and HIV-1-induced effects at the molecular level (Part II).

Single Nuclei Transcriptomics Reveals Obesity-Induced Endothelial and Neurovascular Dysfunction: Implications for Cognitive Decline

Obesity confers risk for cardiovascular disease and vascular dementia. However, genomic alterations modulated by obesity in endothelial cells in the brain and their relationship to other neurovascular unit (NVU) cells are unknown. We performed single nuclei RNA sequencing (snRNAseq) of the NVU (endothelial cells, astrocytes, microglia, and neurons) from the hippocampus of obese (ob/ob) and wild-type (WT) male mice to characterize obesity-induced transcriptomic changes in a key brain memory center and assessed blood-brain barrier permeability (BBB) by gadolinium-enhanced magnetic resonance imaging (MRI). Ob/ob mice displayed obesity, hyperinsulinemia, and impaired glucose tolerance. snRNAseq profiled 14 distinct cell types and 32 clusters within the hippocampus of ob/ob and WT mice and uncovered differentially expressed genes (DEGs) in all NVU cell types, namely, 4462 in neurons, 1386 in astrocytes, 125 in endothelial cells, and 154 in microglia. Gene ontology analysis identified important biological processes such as angiogenesis in endothelial cells and synaptic trafficking in neurons. Cellular pathway analysis included focal adhesion and insulin signaling, which were common to all NVU cell types. Correlation analysis revealed significant positive correlations between endothelial cells and other NVU cell types. Differentially expressed long non-coding RNAs (lncRNAs) were observed in cells of the NVU-affecting pathways such as TNF and mTOR. BBB permeability showed a trend toward increased signal intensity in ob/ob mice. Taken together, our study provides in-depth insight into the molecular mechanisms underlying cognitive dysfunction in obesity and may have implications for therapeutic gene targeting.

A systematic study of molecular targets of cannabidiol in Alzheimer's disease

Background

Alzheimer's disease (AD) is a prevalent, incurable, and chronic neurodegenerative condition characterized by the accumulation of amyloid-β protein (Aβ), disrupting various bodily systems. Despite the lack of a cure, phenolic compounds like cannabidiol (CBD), a non-psychoactive component of cannabis, have emerged as potential therapeutic agents for AD.

Objective

This systematic review explores the impact of different types of cannabidiol on AD, unveiling their neuroprotective mechanisms.

Methods

The research used PubMed, Scopus, and Web of Science databases with keywords like "Alzheimer's disease" and "Cannabidiol." Studies were evaluated based on title, abstract, and relevance to treating AD with CBD. No restrictions on research type or publication year. Excluded were hypothesis papers, reviews, books, unavailable articles, etc.

Results

Microsoft Excel identified 551 articles, with 92 included in the study, but only 22 were thoroughly evaluated. In-vivo and in-silico studies indicate that CBD may disrupt Aβ42, reduce pro-inflammatory molecule release, prevent reactive oxygen species formation, inhibit lipid oxidation, and counteract Aβ-induced increases in intracellular calcium, thereby protecting neurons from apoptosis.

Conclusions

In summary, the study indicates that CBD and its analogs reduce the production of Aβ42. Overall, these findings support the potential of CBD in alleviating the underlying pathology and symptoms associated with AD, underscoring the crucial need for further rigorous scientific investigation to elucidate the therapeutic applications and mechanisms of CBD in AD.

The Identification of Potential Anti-Depression/Anxiety Drug Targets by Stress-Induced Rat Brain Regional Proteome and Network Analyses

Depression and anxiety disorders are prevalent stress-related neuropsychiatric disorders and involve multiple molecular changes and dysfunctions across various brain regions. However, the specific and shared pathophysiological mechanisms occurring in these regions remain unclear. Previous research used a rat model of chronic mild stress (CMS) to segregate and identify depression-susceptible, anxiety-susceptible, and insusceptible groups; then the proteomes of six distinct brain regions (the hippocampus, prefrontal cortex, hypothalamus, pituitary, olfactory bulb, and striatum) were separately and quantitatively analyzed. To gain a comprehensive and systematic understanding of the molecular abnormalities, this study aimed to investigate and compare differential proteomics data from the six regions. Differentially expressed proteins (DEPs) were identified in between specific regions and across all regions and subjected to a series of bioinformatics analyses. Regional comparisons showed that stress-induced proteomic changes and corresponding gene ontology and pathway enrichments were largely distinct, attributable to differences in cell populations, protein compositions, and brain functions of these areas. Additionally, a notable degree of overlap in the significantly enriched terms was identified, potentially suggesting strong connections in the enrichment across different regions. Furthermore, intra-regional and inter-regional protein-protein interaction networks and drug-target-DEP networks were constructed. Integrated analysis of the three association networks in the six regions, along with the DisGeNET database, identified ten DEPs as potential targets for anti-depression/anxiety drugs. Collectively, these findings revealed commonalities and differences across different brain regions at the protein level induced by CMS, and identified several novel protein targets for the development of new therapeutics for depression and anxiety.

Molecular profiling of a rat model of vascular dementia: Evidences from proteomics, metabolomics and experimental validations

Decrease of cerebral blood flow is the primary cause of vascular dementia (VD), but its pathophysiological mechanisms are still not known. This study aims to profile the molecular changes of a rat model of VD induced by bilateral common carotid artery ligation. The Morris water maze and new object recognition tasks were used to test the cognitive function of rats. Hematoxylin and Eosin (HE) staining was used to detect pathological changes in the hippocampus. After confirming the model, proteomics was used to detect differentially expressed proteins in the hippocampus, and metabolomics was used to detect differential metabolites in rat serum. Thereafter, bioinformatics were used to integrate and analyze the potential molecular profile. The results showed that compared with the sham control group, the spatial and recognition memory of the rats were significantly reduced, and pathological changes were observed in the hippocampal CA1 region of the model group. Proteomic analysis suggested 206 differentially expressed proteins in the hippocampus of VD rats, with 117 proteins upregulated and 89 downregulated. Protein-protein interaction network analysis suggested that those differentially expressed proteins might play crucial roles in lipid metabolism, cell adhesion, intracellular transport, and signal transduction. Metabolomics analysis identified 103 differential metabolites, and comparison with the human metabolome database revealed 22 common metabolites, which predicted 265 potential targets. Afterwards, by intersecting the predicted results from metabolomics with the differentially expressed proteins from proteomics, we identified five potential targets, namely ACE, GABBR1, Rock1, Abcc1 and Mapk10. Furthermore, western blotting confirmed that compared with control group, hippocampal GABBR1 and Rock1 were enhanced in the model group. Together, this study showed the molecular profile of VD rats through a combination of proteomics, metabolomics, and experimental confirmation methods, offering crucial molecular targets for the diagnosis and treatment of VD.

Developmental exposure to nonylphenol leads to depletion of the neural precursor cell pool in the hippocampal dentate gyrus

Developmental exposure to nonylphenol (NP) results in irreversible impairments of the central nervous system (CNS). The neural precursor cell (NPC) pool located in the subgranular zone (SGZ), a substructure of the hippocampal dentate gyrus, is critical for the development of hippocampal circuits and some hippocampal functions such as learning and memory. However, the effects of developmental exposure to NP on this pool remain unclear. Thus, our aim was to clarify the impacts of developmental exposure to NP on this pool and to explore the potential mechanisms. Animal models of developmental exposure to NP were created by treating Wistar rats with NP during pregnancy and lactation. Our data showed that developmental exposure to NP decreased Sox2-and Ki67-positive cells in the SGZ of offspring. Inhibited activation of Shh signaling and decreased levels of its downstream mediators, E2F1 and cyclins, were also observed in pups developmentally exposed to NP. Moreover, we established the in vitro model in the NE-4C cells, a neural precursor cell line, to further investigate the effect of NP exposure on NPCs and the underlying mechanisms. Purmorphamine, a small purine-derived hedgehog agonist, was used to specifically modulate the Shh signaling. Consistent with the in vivo results, exposure to NP reduced cell proliferation by inhibiting the Shh signaling in NE-4C cells, and purmorphamine alleviated this reduction in cell proliferation by restoring this signaling. Altogether, our findings support the idea that developmental exposure to NP leads to inhibition of the NPC proliferation and the NPC pool depletion in the SGZ located in the dentate gyrus. Furthermore, we also provided the evidence that suppressed activation of Shh signaling may contribute to the effects of developmental exposure to NP on the NPC pool.

β-chitosan attenuates hepatic macrophage-driven inflammation and reverses aging-related cognitive impairment

Recently, increasing evidence has shown the association between liver abnormal inflammation and cognition impairment, yet their age-related pathogenesis remains obscure. Here, our study provides a potential mechanistic link between liver macrophage excessive activation and neuroinflammation in aging progression. In aged and LPS-injected C57BL/6J mice, systemic administration of β-chitosan ameliorates hepatic macrophage-driven inflammation and reduces peripheral accumulations of TNF-α and IL-1β. Downregulation of circulatory pro-inflammatory cytokines then decreases vascular VCAM1 expression and neuroinflammation in the hippocampus, leading to cognitive improvement in aged/LPS-stimulated mice. Interestingly, β-chitosan treatment also exhibits the beneficial effects on the behavioral recovery of aged/LPS-stimulated zebrafish and Caenorhabditis elegans. In our cell culture and molecular docking experiments, we found that β-chitosan prefers shielding the MD-2 pocket, thus blocking the activation of TLR4-MD-2 complex to suppress NF-κB signaling pathway activation. Together, our findings highlight the extensive therapeutic potential of β-chitosan in reversing aged-related/LPS-induced cognitive impairment via the liver-brain axis.

The intricate interplay between microglia and adult neurogenesis in Alzheimer's disease

Microglia, the resident immune cells of the central nervous system, play a crucial role in regulating adult neurogenesis and contribute significantly to the pathogenesis of Alzheimer's disease (AD). Under physiological conditions, microglia support and modulate neurogenesis through the secretion of neurotrophic factors, phagocytosis of apoptotic cells, and synaptic pruning, thereby promoting the proliferation, differentiation, and survival of neural progenitor cells (NPCs). However, in AD, microglial function becomes dysregulated, leading to chronic neuroinflammation and impaired neurogenesis. This review explores the intricate interplay between microglia and adult neurogenesis in health and AD, synthesizing recent findings to provide a comprehensive overview of the current understanding of microglia-mediated regulation of adult neurogenesis. Furthermore, it highlights the potential of microglia-targeted therapies to modulate neurogenesis and offers insights into potential avenues for developing novel therapeutic interventions.

Understanding the human conflict processing network: A review of the literature on direct neural recordings during performance of a modified stroop task

The Stroop Task is a well-known neuropsychological task developed to investigate conflict processing in the human brain. Our group has utilized direct intracranial neural recordings in various brain regions during performance of a modified color-word Stroop Task to gain a mechanistic understanding of non-emotional human conflict processing. The purpose of this review article is to: 1) synthesize our own studies into a model of human conflict processing, 2) review the current literature on the Stroop Task and other conflict tasks to put our research in context, and 3) describe how these studies define a network in conflict processing. The figures presented are reprinted from our prior publications and key publications referenced in the manuscript. We summarize all studies to date that employ invasive intracranial recordings in humans during performance of conflict-inducing tasks. For our own studies, we analyzed local field potentials (LFPs) from patients with implanted stereotactic electroencephalography (SEEG) electrodes, and we observed intracortical oscillation patterns as well as intercortical temporal relationships in the hippocampus, amygdala, and orbitofrontal cortex (OFC) during the cue-processing phase of a modified Stroop Task. Our findings suggest that non-emotional human conflict processing involves modulation across multiple frequency bands within and between brain structures.

Tet1-mediated 5hmC regulates hippocampal neuroinflammation via wnt signaling as a novel mechanism in obstructive sleep apnoea leads to cognitive deficit

BACKGROUND

Obstructive sleep apnoea (OSA) is a sleep-disordered breathing characterized by intermittent hypoxia (IH) that may cause cognitive dysfunction. However, the impact of IH on molecular processes involved in cognitive function remains unclear.

METHODS

C57BL / 6 J mice were exposed to either normoxia (control) or IH for 6 weeks. DNA hydroxymethylation was quantified by hydroxymethylated DNA immunoprecipitation (hMeDIP) sequencing. ten-eleven translocation 1 (Tet1) was knocked down by lentivirus. Specifically, cognitive function was assessed by behavioral experiments, pathological features were assessed by HE staining, the hippocampal DNA hydroxymethylation was examined by DNA dot blot and immunohistochemical staining, while the Wnt signaling pathway and its downstream effects were studied using qRT-PCR, immunofluorescence staining, and Luminex liquid suspension chip analysis.

RESULTS

IH mice showed pathological changes and cognitive dysfunction in the hippocampus. Compared with the control group, IH mice exhibited global DNA hydroxylmethylation in the hippocampus, and the expression of three hydroxylmethylases increased significantly. The Wnt signaling pathway was activated, and the mRNA and 5hmC levels of Wnt3a, Ccnd2, and Prickle2 were significantly up-regulated. Further caused downstream neurogenesis abnormalities and neuroinflammatory activation, manifested as increased expression of IBA1 (a marker of microglia), GFAP (a marker of astrocytes), and DCX (a marker of immature neurons), as well as a range of inflammatory cytokines (e.g. TNFa, IL3, IL9, and IL17A). After Tet1 knocked down, the above indicators return to normal.

CONCLUSION

Activation of Wnt signaling pathway by hippocampal Tet1 is associated with cognitive dysfunction induced by IH.

Albiflorin alleviates neuroinflammation of rats after MCAO via PGK1/Nrf2/HO-1 signaling pathway

Ischemic stroke is acknowledged as one of the most frequent causes of death and disability, in which neuroinflammation plays a critical role. Emerging evidence supports that the PGK1/Nrf2/HO-1 signaling can modulate inflammation and oxidative injury. Albiflorin (ALB), a main component of Radix paeoniae Alba, possesses anti-inflammatory and antioxidative properties. However, how it exerts a protective role still needs further exploration. In our study, the middle cerebral artery occlusion (MCAO) model was established, and the Longa score was applied to investigate the degree of neurological impairment. Dihydroethidium (DHE) staining and Malondialdehyde (MDA) assay were used to detect the level of lipid peroxidation. 2, 3, 5-Triphenyltetrazolium chloride (TTC) staining was used to measure the infarct area. Evans blue staining was employed to observe the integrality of the blood-brain barrier (BBB). The injury of brain tissue in each group was observed via HE staining. Immunofluorescence staining, enzyme-linked immunosorbent assay (ELISA) and western blot assay were used for the measurement of inflammatory factors and protein levels. We finally observed that ALB relieved cerebral infarction symptoms, attenuated oxidative damage in brain tissues, and reduced neuroinflammation and cell injury in MCAO rats. The overexpression of PGK1 abrogated the protective effect of ALB after experimental cerebral infarction. ALB promoted PGK1 degradation and induced Nrf2 signaling cascade activation for subsequent anti-inflammatory and antioxidant damage. Generally speaking, ALB exerted a protective role in treating cerebral ischemia, and it might target at PGK1/Nrf2/HO-1 signaling. Thus, ALB might be a potential therapeutic agent to alleviate neuroinflammation and protect brain cells after cerebral infarction.

Integrative Analysis of the Age-Related Dysregulated Genes Reveals an Inflammation and Immunity-Associated Regulatory Network in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disease with a long incubation period. While extensive research has led to the construction of long non-coding RNA (lncRNA)-associated competing endogenous RNA (ceRNA) regulatory networks, which primarily derived from differential analyses between clinical AD patients and control individuals or mice, there remains a critical knowledge gap pertaining to the dynamic alterations in transcript expression profiles that occur with age, spanning from the pre-symptomatic stage to the onset of AD. In the present study, we examined the transcriptomic changes in AD model mice at three distinct stages: the unaffected (un-) stage, the pre-onset stage, and the late-onset stage, and identified 14, 57, and 99 differentially expressed mRNAs (DEmRs) in AD model mice at 3, 6, and 12 months, respectively. Among these, we pinpointed 16 mRNAs closely associated with inflammation and immunity and excavated their lncRNA-mRNA regulatory network based on a comprehensive analysis. Notably, our preliminary analysis suggested that four lncRNAs (NONMMUT102943, ENSMUST00000160309, NONMMUT083044, and NONMMUT126468), eight miRNAs (miR-34a-5p, miR-22-5p, miR-302a/b-3p, miR-340-5p, miR-376a/b-5p, and miR-487b-5p), and four mRNAs (C1qa, Cd68, Ctss, and Slc11a1) may play pivotal roles in orchestrating immune and inflammatory responses during the early stages of AD. Our study has unveiled age-related AD risk genes, and provided an analytical framework for constructing lncRNA-mRNA networks using time series data and correlation analysis. Most notably, we have successfully constructed a comprehensive regulatory ceRNA network comprising genes intricately linked to inflammatory and immune functions in AD.

Inhibition of Endoplasmic Reticulum Stress Improves Chronic Ischemic Hippocampal Damage Associated with Suppression of IRE1α/TRAF2/ASK1/JNK-Dependent Apoptosis

Chronic cerebral ischemia is a complex form of stress, of which the most common hemodynamic characteristic is chronic cerebral hypoperfusion (CCH). Lasting endoplasmic reticulum (ER) stress can drive neurological disorders. Targeting ER stress shows potential neuroprotective effects against stroke. However, the role of ER stress in CCH pathological processes and the effects of targeting ER stress on brain ischemia are unclear. Here, a CCH rat model was established by bilateral common carotid artery occlusion. Rats were treated with 4-PBA, URB597, or both for 4 weeks. Neuronal morphological damage was detected using hematoxylin-eosin staining. The expression levels of the ER stress-ASK1 cascade-related proteins GRP78, IRE1α, TRAF2, CHOP, Caspase-12, ASK1, p-ASK1, JNK, and p-JNK were assessed by Western blot. The mRNA levels of TNF-α, IL-1β, and iNOS were assessed by RT-PCR. For oxygen-glucose deprivation experiments, mouse hippocampal HT22 neurons were used. Apoptosis of the hippocampus and HT22 cells was detected by TUNEL staining and Annexin V-FITC analysis, respectively. CCH evoked ER stress with increased expression of GRP78, IRE1α, TRAF2, CHOP, and Caspase-12. Co-immunoprecipitation experiments confirmed the interaction between TRAF2 and ASK1. ASK1/JNK signaling, inflammatory cytokines, and neuronal apoptosis were enhanced, accompanied by persistent ER stress; these were reversed by 4-PBA and URB597. Furthermore, the ASK1 inhibitor GS4997 and 4-PBA displayed synergistic anti-apoptotic effects in cells with oxygen-glucose deprivation. In summary, ER stress-induced apoptosis in CCH is associated with the IRE1α/TRAF2/ASK1/JNK signaling pathway. Targeting the ER stress-ASK1 cascade could be a novel therapeutic approach for ischemic cerebrovascular diseases.

Emerging phosphodiesterase inhibitors for treatment of neurodegenerative diseases

Neurodegenerative diseases (NDs) cause progressive loss of neuron structure and ultimately lead to neuronal cell death. Since the available drugs show only limited symptomatic relief, NDs are currently considered as incurable. This review will illustrate the principal roles of the signaling systems of cyclic adenosine and guanosine 3',5'-monophosphates (cAMP and cGMP) in the neuronal functions, and summarize expression/activity changes of the associated enzymes in the ND patients, including cyclases, protein kinases, and phosphodiesterases (PDEs). As the sole enzymes hydrolyzing cAMP and cGMP, PDEs are logical targets for modification of neurodegeneration. We will focus on PDE inhibitors and their potentials as disease-modifying therapeutics for the treatment of Alzheimer's disease, Parkinson's disease, and Huntington's disease. For the overlapped but distinct contributions of cAMP and cGMP to NDs, we hypothesize that dual PDE inhibitors, which simultaneously regulate both cAMP and cGMP signaling pathways, may have complementary and synergistic effects on modifying neurodegeneration and thus represent a new direction on the discovery of ND drugs.

Effect of astaxanthin in type-2 diabetes -induced APPxhQC transgenic and NTG mice

OBJECTIVES

Aggregation and misfolding of amyloid beta (Aβ) and tau proteins, suggested to arise from post-translational modification processes, are thought to be the main cause of Alzheimer's disease (AD). Additionally, a plethora of evidence exists that links metabolic dysfunctions such as obesity, type 2 diabetes (T2D), and dyslipidemia to the pathogenesis of AD. We thus investigated the combinatory effect of T2D and human glutaminyl cyclase activity (pyroglutamylation), on the pathology of AD and whether astaxanthin (ASX) treatment ameliorates accompanying pathophysiological manifestations.

METHODS

Male transgenic AD mice, APPxhQC, expressing human APP751 with the Swedish and the London mutation and human glutaminyl cyclase (hQC) enzyme and their non-transgenic (NTG) littermates were used. Both APPxhQC and NTG mice were allocated to 3 groups, control, T2D-control, and T2D-ASX. Mice were fed control or high fat diet ± ASX for 13 weeks starting at an age of 11-12 months. High fat diet fed mice were further treated with streptozocin for T2D induction. Effects of genotype, T2D induction, and ASX treatment were evaluated by analysing glycemic readouts, lipid concentration, Aβ deposition, hippocampus-dependent cognitive function and nutrient sensing using immunosorbent assay, ELISA-based assays, western blotting, immunofluorescence staining, and behavioral testing via Morris water maze (MWM), respectively.

RESULTS

APPxhQC mice presented a higher glucose sensitivity compared to NTG mice. T2D-induced brain dysfunction was more severe in NTG compared to the APPxhQC mice. T2D induction impaired memory functions while increasing hepatic LC3B, ABCA1, and p65 levels in NTG mice. T2D induction resulted in a progressive shift of Aβ from the soluble to insoluble form in APPxhQC mice. ASX treatment reversed T2D-induced memory dysfunction in NTG mice and in parallel increased hepatic pAKT while decreasing p65 and increasing cerebral p-S6rp and p65 levels. ASX treatment reduced soluble Aβ38 and Aβ40 and insoluble Aβ40 levels in T2D-induced APPxhQC mice.

CONCLUSIONS

We demonstrate that T2D induction in APPxhQC mice poses additional risk for AD pathology as seen by increased Aβ deposition. Although ASX treatment reduced Aβ expression in T2D-induced APPxhQC mice and rescued T2D-induced memory impairment in NTG mice, ASX treatment alone may not be effective in cases of T2D comorbidity and AD.

Mapping the current trends and hotspots of adult hippocampal neurogenesis from 2004-2023: a bibliometric analysis

Objective

We utilized bibliometric and data visualization techniques to discern the primary research domains and emerging frontiers in the field of adult hippocampal neurogenesis (AHN).

Methods

We systematically searched the Web of Science database for AHN-related articles published between 2004 and 2023. The retrieved articles were filtered based on publication types (articles and reviews) and language (English). We employed CiteSpace, VOSviewer, and the online bibliometric platform (bibliometric.com) to visualize and analyze the collected data.

Results

In total, 1,590 AHN-related publications were discovered, exhibiting a steady increase in yearly publications over time. The United States emerged as the leading contributor in AHN research in terms of both publication quantity and national influence. Among all research institutions in the field of AHN, the University of California System exhibited the highest impact. Kempermann, Gerd was the most active author. The publications of the top three active authors primarily focused on the functions of AHN, and reversing hippocampal damage and cognitive impairment by improving AHN. An analysis of reference co-citation clustering revealed 8 distinct research clusters, and the notable ones included "adult hippocampal neurogenesis," "neurogenesis," "hippocampus," "dentate gyrus," "neural stem cell," and "depression." Additionally, a burst keyword detection indicated that 'anxiety' is a current research hotspot in the field of AHN.

Conclusion

This in-depth bibliographic assessment of AHN offers a deeper insight into the present research hotspots in the field. The association between AHN and cognitive diseases, such as Alzheimer's disease (AD) and anxiety, has emerged as a prominent research hotspot.

Effect of total flavonoids of Dracocephalum moldavica L. On neuroinflammation in Alzheimer's disease model amyloid-β (Aβ1-42)-peptide-induced astrocyte activation

One of the main pathological features noted in Alzheimer's disease (AD) is the presence of plagues of aggregated β-amyloid (Aβ1-42)-peptides. Excess deposition of amyloid-β oligomers (AβO) are known to promote neuroinflammation. Sequentially, following neuroinflammation astrocytes become activated with cellular characteristics to initiate activated astrocytes. The purpose of this study was to determine whether total flavonoids derived from Dracocephalum moldavica L. (TFDM) inhibited Aβ1-42-induced damage attributed to activated C8-D1A astrocytes. Western blotting and ELISA were used to determine the expression of glial fibrillary acidic protein (GFAP), and complement C3 to establish the activation status of astrocytes following induction from exposure to Aβ1-42. Data demonstrated that stimulation of C8-D1A astrocytes by treatment with 40 μM Aβ1-42 for 24 hr produced significant elevation in protein expression and protein levels of acidic protein (GFAP) and complement C3 accompanied by increased expression and levels of inflammatory cytokines. Treatment with TFDM or the clinically employed drug donepezil in AD therapy reduced production of inflammatory cytokines, and toxicity initiated following activation of C8-D1A astrocytes following exposure to Aβ1-42. Therefore, TFDM similar to donepezil inhibited inflammatory secretion in reactive astrocytes, suggesting that TFDM may be considered as a potential compound to be utilized in AD therapy.

Discovery of astragaloside IV against high glucose-induced apoptosis in retinal ganglion cells: Bioinformatics and in vitro studies

OBJECTIVE

To examine the therapeutic mechanism of astragaloside IV (AS-IV) in the management of retinal ganglion cell (RGC) injury induced by high glucose (HG), a comprehensive approach involving the integration of network pharmacology and conducting in vitro and in vivo experiments was utilized.

METHODS

A rat model of diabetic retinopathy (DR) injury was created by administering streptozotocin through intraperitoneal injection. Additionally, a model of RGC injury induced by HG was established using a glucose concentration of 0.3 mmol/mL. Optical coherence tomography (OCT) images were captured 8 weeks after the injection of AS-IV. AS-IV and FBS were added to the culture medium and incubated for 48 h. The viability of cells was assessed using a CCK-8 assay, while the content of reactive oxygen species (ROS) was measured using DCFH-DA. Apoptosis was evaluated using Annexin V-PI. To identify the targets of AS-IV, hyperglycemia, and RGC, publicly available databases were utilized. The Metascape platform was employed for conducting GO and KEGG enrichment analyses. The STRING database in conjunction with Cytoscape 3.7.2 was used to determine common targets of protein-protein interactions (PPIs) and to identify the top 10 core target proteins in the RGC based on the MCC algorithm. qRT-PCR was used to measure the mRNA expression levels of the top10 core target proteins in RGCs.

RESULTS

OCT detection indicated that the thickness of the outer nucleus, and inner and outer accessory layers of the retina increased in the AS-IV treated retina compared to that in the DM group but decreased compared to that in the CON group. Coculturing RGC cells with AS-IV after HG induction resulted in a significant increase in cell viability and a decrease in ROS and apoptosis, suggesting that AS-IV can reduce damage to RGC cells caused by high glucose levels by inhibiting oxidative stress. There were 14 potential targets of AS-IV in the treatment of RGC damage induced by high glucose levels. The top 10 core target proteins identified by the MCC algorithm were HIF1α, AKT1, CTNNB1, SMAD2, IL6, SMAD3, IL1β, PPARG, TGFβ1, and NOTCH3. qRT-PCR analysis showed that AS-IV could upregulate the mRNA expression levels of SMAD3, TGF-β1, and NOTCH3, and downregulate the mRNA expression levels of HIF1α, AKT1, CTNNB1, SMAD2, SMAD3, and IL-1β in high glucose-induced RGC cells.

CONCLUSION

The findings of this study validate the efficacy of astragaloside IV in the treatment of DR and shed light on the molecular network involved. Specifically, HIF1α, AKT1, CTNNB1, SMAD2, SMAD3, and IL-1β were identified as the crucial candidate molecules responsible for the protective effects of astragaloside IV on RGCs.

Adult Neoneurogenesis and Oligodendrogenesis in Multiple Sclerosis: A Systematic Review of Human and Animal Studies

Introduction: The subventricular zone promotes remyelination through activation differentiation of oligodendroglial precursor cells (OPCs) and neural stem cells (NSCs) into mature oligodendrocytes and thus in the adult brain. In multiple sclerosis (MS) this regenerative capability is halted resulting in neurodegeneration. We aimed to systematically search and synthesize evidence on mechanisms and phenomena associated with subventricular zone (SVZ) dysfunction in MS. Materials and Methods: Our systematic review was reported according to the PRISMA-ScR statement. MEDLINE, SCOPUS, ProQuest, and Google Scholar were searched using the terms "subventricular zone" and "multiple sclerosis," including English-written in vivo and postmortem studies. Results: Twenty studies were included. Thirteen studies on models of experimental autoimmune encephalomyelitis (EAE) reported among others strong stathmin immunoreactivity in the SVZ of EAE models, the role of MOG immunization in neurogenesis impairment, the effect of parenchymal OPCs and NSCs in myelin repair, and the importance of ependymal cells (E1/E2) and ciliated B1 cells in SVZ stem cell signaling. CXCR4 signaling and transcriptional profiles of SVZ microglia, Gli1 pathway, and galactin-3 were also explored. Studies in humans demonstrated microstructural SVZ damage in progressive MS and the persistence of black holes near the SVZ, whereas postmortem confirmed the generation of polysialic acid-neural cell adhesion molecule and NG2-positive progenitors through SVZ activation, SVZ stathmin immunoreactivity, Shh pathway, and Gal-3 upregulation. Discussion: Oligodendrogenesis defects translate to reduced remyelination, a hallmark of MS that determines its end-phenotype and disease course. Conclusion: The role of inflammation and subsequent SVZ microenvironment disruption is evident in MS pathology.

Memory circuits in dementia: The engram, hippocampal neurogenesis and Alzheimer's disease

Here, we provide an in-depth consideration of our current understanding of engrams, spanning from molecular to network levels, and hippocampal neurogenesis, in health and Alzheimer's disease (AD). This review highlights novel findings in these emerging research fields and future research directions for novel therapeutic avenues for memory failure in dementia. Engrams, memory in AD, and hippocampal neurogenesis have each been extensively studied. The integration of these topics, however, has been relatively less deliberated, and is the focus of this review. We primarily focus on the dentate gyrus (DG) of the hippocampus, which is a key area of episodic memory formation. Episodic memory is significantly impaired in AD, and is also the site of adult hippocampal neurogenesis. Advancements in technology, especially opto- and chemogenetics, have made sophisticated manipulations of engram cells possible. Furthermore, innovative methods have emerged for monitoring neurons, even specific neuronal populations, in vivo while animals engage in tasks, such as calcium imaging. In vivo calcium imaging contributes to a more comprehensive understanding of engram cells. Critically, studies of the engram in the DG using these technologies have shown the important contribution of hippocampal neurogenesis for memory in both health and AD. Together, the discussion of these topics provides a holistic perspective that motivates questions for future research.

Bifidobacterium pseudocatenulatum NCU-08 ameliorated senescence via modulation of the AMPK/Sirt1 signaling pathway and gut microbiota in mice

Aging is a degenerative disease in which organisms and neurological functions decline. Emerging research has underscored the vital role of the gut microbiota in age-related processes. However, the identification of aging-associated core microbiota remains limited. In this investigation, we isolated a strain of B. pseudocatenulatum NCU-08 from the feces of centenarians and assessed its impact on aging using a mouse model induced by D-gal. Our study revealed the exceptional probiotic attributes of B. pseudocatenulatum NCU-08. Administration of B. pseudocatenulatum NCU-08 significantly ameliorated age-related memory impairment, motor dysfunction, and anxiety-like behaviors in aging mice (p < 0.01). Moreover, tissue staining analysis demonstrated that B. pseudocatenulatum NCU-08 reduced the intensity of SA-β-gal-positive in the hippocampus of aging mice. It also reversed pathological damage and structural abnormalities in brain and intestinal tissue. B. pseudocatenulatum NCU-08 inhibited neuroinflammation induced by TLR4/NF-κB (p < 0.01) and preserved the blood-brain barrier integrity by activating the AMPK/Sirt1 pathway (p < 0.05). Furthermore, it mitigated neuronal apoptosis and oxidative stress by upregulating the PI3K/AKT signaling pathway (p < 0.01) and enhancing the activities of antioxidant enzymes, including GSH-Px (p < 0.01), SOD (p < 0.01), and CAT (p < 0.01). Besides, analysis of 16S rRNA sequencing data demonstrated that treatment with B. pseudocatenulatum NCU-08 restored intestinal microbiota homeostasis after senescence. It enhanced the abundance of beneficial bacteria while suppressing the growth of pathogenic microorganisms. In summary, our study unveiled that this novel strain of B. pseudocatenulatum NCU-08 exerts anti-aging effects through regulating the AMPK/Sirt1 pathway and intestinal microbiota. It holds promise as a functional food for promoting anti-aging effects and offers a novel approach to address aging and associated metabolic disorders.

Advancements in research on the effects of panax notoginseng saponin constituents in ameliorating learning and memory disorders

Learning and memory disorder is a cluster of symptoms caused by neuronal aging and other diseases of the central nervous system (CNS). Panax notoginseng saponins (PNS) are a series of saponins derived from the natural active ingredients of traditional Chinese medicine (TCM) that have neuroprotective effects on the central nervous system. In this paper, we review the ameliorative effects and mechanisms of Panax notoginseng saponin-like components on learning and memory disorders to provide valuable references and insights for the development of new drugs for the treatment of learning and memory disorders. Our summary results suggest that Panax ginseng saponins have significant effects on improving learning and memory disorders, and these effects and potential mechanisms are mediated by their anti-inflammatory, anti-apoptotic, antioxidant, β-amyloid lowering, mitochondrial homeostasis in vivo, neuronal structure and function improving, neurogenesis promoting, neurotransmitter release regulating, and probiotic homeostasis in vivo activities. These findings suggest the potential of Panax notoginseng saponin-like constituents as drug candidates for improving learning and memory disorders.

Sonic hedgehog signalling pathway contributes in age-related disorders and Alzheimer's disease

Alzheimer's disease (AD) is caused by the aging process and manifested by cognitive deficits and progressive memory loss. During aging, several conditions, including hypertension, diabetes, and cholesterol, have been identified as potential causes of AD by affecting Sonic hedgehog (Shh) signalling. In addition to being essential for cell differentiation and proliferation, Shh signalling is involved in tissue repair and the prevention of neurodegeneration. Neurogenesis is dependent on Shh signalling; inhibition of this pathway results in neurodegeneration. Several protein-protein interactions that are involved in Shh signalling are implicated in the pathophysiology of AD like overexpression of the protein nexin-1 inhibits the Shh pathway in AD. A protein called Growth Arrest Specific-1 works with another protein called cysteine dioxygenase (CDO) to boost Shh signalling. CDO is involved in the development of the central nervous system (CNS). Shh signalling strengthened the blood brain barrier and therefore prevent the entry of amyloid beta and other toxins to the brain from periphery. Further, several traditional remedies used for AD and dementia, including Epigallocatechin gallate, yokukansan, Lycium barbarum polysaccharides, salvianolic acid, and baicalin, are known to stimulate the Shh pathway. In this review, we elaborated that the Shh signalling exerts a substantial influence on the pathogenesis of AD. In this article, we have tried to explore the various possible connections between the Shh signalling and various known pathologies of AD.

Astrocytic endothelin-1 overexpression impairs learning and memory ability in ischemic stroke via altered hippocampal neurogenesis and lipid metabolism

Vascular etiology is the second most prevalent cause of cognitive impairment globally. Endothelin-1, which is produced and secreted by endothelial cells and astrocytes, is implicated in the pathogenesis of stroke. However, the way in which changes in astrocytic endothelin-1 lead to poststroke cognitive deficits following transient middle cerebral artery occlusion is not well understood. Here, using mice in which astrocytic endothelin-1 was overexpressed, we found that the selective overexpression of endothelin-1 by astrocytic cells led to ischemic stroke-related dementia (1 hour of ischemia; 7 days, 28 days, or 3 months of reperfusion). We also revealed that astrocytic endothelin-1 overexpression contributed to the role of neural stem cell proliferation but impaired neurogenesis in the dentate gyrus of the hippocampus after middle cerebral artery occlusion. Comprehensive proteome profiles and western blot analysis confirmed that levels of glial fibrillary acidic protein and peroxiredoxin 6, which were differentially expressed in the brain, were significantly increased in mice with astrocytic endothelin-1 overexpression in comparison with wild-type mice 28 days after ischemic stroke. Moreover, the levels of the enriched differentially expressed proteins were closely related to lipid metabolism, as indicated by Kyoto Encyclopedia of Genes and Genomes pathway analysis. Liquid chromatography-mass spectrometry nontargeted metabolite profiling of brain tissues showed that astrocytic endothelin-1 overexpression altered lipid metabolism products such as glycerol phosphatidylcholine, sphingomyelin, and phosphatidic acid. Overall, this study demonstrates that astrocytic endothelin-1 overexpression can impair hippocampal neurogenesis and that it is correlated with lipid metabolism in poststroke cognitive dysfunction.

Asthma aggravates alzheimer's disease by up-regulating NF- κB signaling pathway through LTD4

Clinical studies have shown that asthma is a risk factor for dementia or Alzheimer's disease (AD). To investigate whether asthma aggravates AD in APP/PS1 mice and explore the potential mechanisms, an asthma model was established using six-month-old APP/PS1 mice, and montelukast was used as a therapeutic agent in APP/PS1 mice with asthma. The Morris water maze test showed that asthma aggravates spatial learning and memory abilities. Asthma also upregulates the NF-κB inflammatory pathway in APP/PS1 mice and promotes the expression of beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), amyloid-β (Aβ) deposition, neuronal damage, synaptic plasticity deficiency, activation of microglia and astrocytes. The level of LTD4 and its receptor CysLT1R in the hippocampus of APP/PS1 mice after the asthma modeling was established was higher than that in APP/PS1 mice, suggesting that asthma may affect the pathology of AD through LTD4 and its receptor Cys-LT1R. Montelukast ameliorates these pathological changes and cognitive impairment. These results suggest that asthma aggravates AD pathology and cognitive impairment of APP/PS1 mice via upregulation of the NF-κB inflammatory pathway, and montelukast ameliorates these pathological changes.

Dexmedetomidine Stereotaxic Injection Alleviates Neuronal Loss Following Bilateral Common Carotid Artery Occlusion via Up-Regulation of BDNF Expression

BACKGROUND/AIM

Neurogenesis is an important process in the recovery from neurological damage caused by ischemic lesions. Endogenous neurogenesis is insufficient to restore neuronal damage following cerebral ischemia. Dexmedetomidine (DEX) exerts neuroprotective effects against cerebral ischemia and ischemia/reperfusion injury. DEX promotes neurogenesis, including neuronal proliferation and maturation in the hippocampus. In a previous study, we showed that early neurogenesis increased 3 days after bilateral common carotid artery occlusion (BCCAO). In this study, we investigated the effect of DEX on neurogenesis 3 days after BCCAO.

MATERIALS AND METHODS

Male Sprague-Dawley (SD) rats (7-8 weeks old) were used as a BCCAO model. Right and left common carotid arteries of the rats were occluded using 4-0 silk sutures. Two hours after surgery, an intracranial DEX injection was administered to rats that underwent surgery using a stereotaxic injector. Brains were obtained from control and BCCAO rats 3 days after surgery. Immunohistochemistry was performed on the cortex and dentate gyrus of the hippocampus using a NeuN antibody. Western blot was performed with HIF1α and brain-derived neurotrophic factor (BDNF) antibodies.

RESULTS

The number of mature neurons decreased 3 days after BCCAO, but DEX treatment alleviated neural loss in the parietal cortex and hippocampus. Up-regulation of BDNF was also observed after dexmedetomidine treatment.

CONCLUSION

Stereotaxic injection of dexmedetomidine alleviates neural loss following BCCAO by up-regulating BDNF expression.

Atorvastatin Calcium Ameliorates Cognitive Deficits Through the AMPK/Mtor Pathway in Rats with Vascular Dementia

AIM

In this study, the protective effects of atorvastatin calcium (AC) on nerve cells and cognitive improvement in vivo and in vitro were investigated by establishing cell models and vascular dementia (VD) rat models.

BACKGROUND

VD is a neurodegenerative disease characterized by cognitive deficits caused by chronic cerebral hypoperfusion. AC has been studied for its potential to cure VD but its efficacy and underlying mechanism are still unclear.

OBJECTIVE

The mechanism of action of AC on cognitive deficits in the early stages of VD is unclear. Here, the 2-vessel occlusion (2-VO) model in vivo and the hypoxia/reoxygenation (H/R) cell model in vitro was established to investigate the function of AC in VD.

METHODS

The spatial learning and memory abilities of rats were detected by the Morris method. The IL-6, tumour necrosis factor-α (TNF-α), malondialdehyde (MDA) and superoxide dismutase (SOD) in cell supernatant was tested by ELISA kits. After behavioural experiments, rats were anaesthetized and sacrificed, and their brains were extracted. One part was immediately fixed in 4% paraformaldehyde for H&E, Nissl, and immunohistochemical analyses, and the other was stored in liquid nitrogen. All data were shown as mean ± SD. Statistical comparison between the two groups was performed by Student's t-test. A two-way ANOVA test using GraphPad Prism 7 was applied for escape latency analysis and the swimming speed test. The difference was considered statistically significant at p < 0.05.

RESULTS

AC decreased apoptosis, increased autophagy, and alleviated oxidative stress in primary hippocampal neurons. AC regulated autophagy-related proteins in vitro by western blotting. VD mice improved cognitively in the Morris water maze. Spatial probing tests showed that VD animals administered AC had considerably longer swimming times to the platform than VD rats. H&E and Nissl staining showed that AC reduces neuronal damage in VD rats. Western blot and qRT-PCR indicated that AC in VD rats inhibited Bax and promoted LC3-II, Beclin-1, and Bcl-2 in the hippocampus region. AC also improves cognition via the AMPK/mTOR pathway.

CONCLUSION

This study found that AC may relieve learning and memory deficits as well as neuronal damage in VD rats by changing the expression of apoptosis/autophagy-related genes and activating the AMPK/mTOR signalling pathway in neurons.

Adult neurogenesis research in China

Neural stem cells are multipotent stem cells that generate functional newborn neurons through a process called neurogenesis. Neurogenesis in the adult brain is tightly regulated and plays a pivotal role in the maintenance of brain function. Disruption of adult neurogenesis impairs cognitive function and is correlated with numerous neurologic disorders. Deciphering the mechanisms underlying adult neurogenesis not only advances our understanding of how the brain functions, but also offers new insight into neurologic diseases and potentially contributes to the development of effective treatments. The field of adult neurogenesis is experiencing significant growth in China. Chinese researchers have demonstrated a multitude of factors governing adult neurogenesis and revealed the underlying mechanisms of and correlations between adult neurogenesis and neurologic disorders. Here, we provide an overview of recent advancements in the field of adult neurogenesis due to Chinese scientists.

Tpr Misregulation in Hippocampal Neural Stem Cells in Mouse Models of Alzheimer's Disease

Nuclear pore complexes (NPCs) are highly dynamic macromolecular protein structures that facilitate molecular exchange across the nuclear envelope. Aberrant NPC functioning has been implicated in neurodegeneration. The translocated promoter region (Tpr) is a critical scaffolding nucleoporin (Nup) of the nuclear basket, facing the interior of the NPC. However, the role of Tpr in adult neural stem/precursor cells (NSPCs) in Alzheimer's disease (AD) is unknown. Using super-resolution (SR) and electron microscopy, we defined the different subcellular localizations of Tpr and phospho-Tpr (P-Tpr) in NSPCs in vitro and in vivo. Elevated Tpr expression and reduced P-Tpr nuclear localization accompany NSPC differentiation along the neurogenic lineage. In 5xFAD mice, an animal model of AD, increased Tpr expression in DCX+ hippocampal neuroblasts precedes increased neurogenesis at an early stage, before the onset of amyloid-β plaque formation. Whereas nuclear basket Tpr interacts with chromatin modifiers and NSPC-related transcription factors, P-Tpr interacts and co-localizes with cyclin-dependent kinase 1 (Cdk1) at the nuclear chromatin of NSPCs. In hippocampal NSPCs in a mouse model of AD, aberrant Tpr expression was correlated with altered NPC morphology and counts, and Tpr was aberrantly expressed in postmortem human brain samples from patients with AD. Thus, we propose that altered levels and subcellular localization of Tpr in CNS disease affect Tpr functionality, which in turn regulates the architecture and number of NSPC NPCs, possibly leading to aberrant neurogenesis.

Long-term intake of α-glycerophosphocholine (GPC) suppresses microglial inflammation and blood-brain barrier (BBB) disruption and promotes neurogenesis in senescence-accelerated mice prone 8 (SAMP8)

We evaluated the effects of long-term glycerophosphocholine (GPC) intake on microglia, the blood-brain barrier (BBB), and neurogenesis in senescence-accelerated mice prone 8 (SAMP8). The GPC intake suppressed microglial activation and BBB disruption and sustained doublecortin-positive cells in the hippocampus. The results indicate that GPC intake exerts anti-inflammatory and neuroprotective effects in the brain of aged mice.

Detrimental Effects of ApoE ε4 on Blood-Brain Barrier Integrity and Their Potential Implications on the Pathogenesis of Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease representing the most common type of dementia in older adults. The major risk factors include increased age, genetic predisposition and socioeconomic factors. Among the genetic factors, the apolipoprotein E (ApoE) ε4 allele poses the greatest risk. Growing evidence suggests that cerebrovascular dysfunctions, including blood-brain barrier (BBB) leakage, are also linked to AD pathology. Within the scope of this paper, we, therefore, look upon the relationship between ApoE, BBB integrity and AD. In doing so, both brain-derived and peripheral ApoE will be considered. Despite the considerable evidence for the involvement of brain-derived ApoE ε4 in AD, information about the effect of peripheral ApoE ε4 on the central nervous system is scarce. However, a recent study demonstrated that peripheral ApoE ε4 might be sufficient to impair brain functions and aggravate amyloid-beta pathogenesis independent from brain-based ApoE ε4 expression. Building upon recent literature, we provide an insight into the latest research that has enhanced the understanding of how ApoE ε4, secreted either in the brain or the periphery, influences BBB integrity and consequently affects AD pathogenesis. Subsequently, we propose a pathway model based on current literature and discuss future research perspectives.

Hippocampal atrophy is associated with hearing loss in cognitively normal adults

Objectives

A growing body of evidence suggests that age-related hearing loss (HL) is associated with morphological changes of the cerebral cortex, but the results have been drawn from a small amount of data in most studies. The aim of this study is to investigate the correlation between HL and gray matter volume (GMV) in a large number of subjects, strictly controlling for an extensive set of possible biases.

Methods

Medical records of 576 subjects who underwent pure tone audiometry, brain magnetic resonance imaging (MRI), and the Korean Mini-Mental State Exam (K-MMSE) were reviewed. Among them, subjects with normal cognitive function and free of central nervous system disorders or coronary artery disease were included. Outliers were excluded after a sample homogeneity check. In the end, 405 subjects were enrolled. Pure tone hearing thresholds were determined at 0.5, 1, 2, and 4 kHz in the better ear. Enrolled subjects were divided into 3 groups according to pure tone average: normal hearing (NH), mild HL (MHL), and moderate-to-severe HL (MSHL) groups. Using voxel-based morphometry, we evaluated GMV changes that may be associated with HL. Sex, age, total intracranial volume, type of MRI scanner, education level, K-MMSE score, smoking status, and presence of hypertension, diabetes mellitus and dyslipidemia were used as covariates.

Results

A statistically significant negative correlation between the hearing thresholds and GMV of the hippocampus was elucidated. Additionally, in group comparisons, the left hippocampal GMV of the MSHL group was significantly smaller than that of the NH and MHL groups.

Conclusion

Based on the negative correlation between hearing thresholds and hippocampal GMV in cognitively normal old adults, the current study indicates that peripheral deafferentation could be a potential contributing factor to hippocampal atrophy.

Genome-wide association study of hippocampal blood-oxygen-level-dependent-cerebral blood flow correlation in Chinese Han population

Correlation between blood-oxygen-level-dependent (BOLD) and cerebral blood flow (CBF) has been used as an index of neurovascular coupling. Hippocampal BOLD-CBF correlation is associated with neurocognition, and the reduced correlation is associated with neuropsychiatric disorders. We conducted the first genome-wide association study of the hippocampal BOLD-CBF correlation in 4,832 Chinese Han subjects. The hippocampal BOLD-CBF correlation had an estimated heritability of 16.2-23.9% and showed reliable genome-wide significant association with a locus at 3q28, in which many variants have been linked to neuroimaging and cerebrospinal fluid markers of Alzheimer's disease. Gene-based association analyses showed four significant genes (GMNC, CRTC2, DENND4B, and GATAD2B) and revealed enrichment for mast cell calcium mobilization, microglial cell proliferation, and ubiquitin-related proteolysis pathways that regulate different cellular components of the neurovascular unit. This is the first unbiased identification of the association of hippocampal BOLD-CBF correlation, providing fresh insights into the genetic architecture of hippocampal neurovascular coupling.

Effects of e-vapour and high-fat diet on the immunohistochemical staining of nicotinic acetylcholine receptors, apoptosis, microglia and astrocytes in the adult male mouse hippocampus

The use of e-cigarettes/e-vapour, and the consumption of a high-fat diet (HFD), are two popular lifestyle choices associated with alterations in the hippocampus. This study, using a mouse model, investigated the effects of exposure to e-vapour (± nicotine) and HFD (43% fat) consumption, on the expression of nicotinic acetylcholine receptor (nAChR) subunits α3, α4, α7 and β2, apoptosis markers caspase-3 and TUNEL, microglial marker Iba-1, and astrocyte marker GFAP, in hippocampal subregions of dentate gyrus (DG) and cornu ammonis (CA) 1-3. The major findings included: (1) HFD alone had minimal effect with no consistent pattern or interaction between the markers, (2) E-vapour (± nicotine) predominantly affected the CA2 subregion, decreasing α7 and β2 nAChR subunits and Iba-1, (3) Nicotine e-vapour increased TUNEL across all subregions, and (4) HFD, in the presence of nicotine-free e-vapour, decreased caspase-3 and increased TUNEL across all regions, and decreased Iba-1 in the CA subregions, while HFD and nicotine-containing e-vapour, subregion specifically affected the α3, α4 and α7 nAChR subunits, with a protective effect against change in GFAP in the DG and Iba-1 in the CA1 and CA3. These findings highlight that e-vapour itself alters nAChRs, particularly in the CA2 subregion, associated with a decrease in neuroinflammatory response (Iba-1) across the whole hippocampus, and the addition of nicotine increases cell apoptosis across the whole hippocampus. HFD alone was not detrimental in our model, but in the presence of nicotine-free e-vapour, it differentially affected apoptosis, while the addition of nicotine increased nAChR subunits.

Expression patterns of AEG-1 in the normal brain

Astrocyte elevated gene-1 (AEG-1) is a well-known oncogene implicated in various types of human cancers, including brain tumors. Recently, AEG-1 has also been reported to play pivotal roles in glioma-associated neurodegeneration and neurodegenerative diseases like Parkinson's disease and amyotrophic lateral sclerosis. However, the normal physiological functions and expression patterns of AEG-1 in the brain are not well understood. In this study, we investigated the expression patterns of AEG-1 in the normal mouse brain and found that AEG-1 is widely expressed in neurons and neuronal precursor cells, but little in glial cells. We observed differential expression levels of AEG-1 in various brain regions, and its expression was mainly localized in the cell body of neurons rather than the nucleus. Additionally, AEG-1 was expressed in the cytoplasm of Purkinje cells in both the mouse and human cerebellum, suggesting its potential role in this brain region. These findings suggest that AEG-1 may have important functions in normal brain physiology and warrant further investigation. Our results may also shed light on the differential expression patterns of AEG-1 in normal and pathological brains, providing insights into its roles in various neurological disorders.