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

The effects of APOEe4 allele on cerebral structure, function, and related interactions with cognition in young adults

In the last decade, extensive research has emerged into understanding the impact of risk factors for Alzheimer's Disease (AD) on brain in pre-symptomatic stages. We investigated the neuroimaging correlates of the APOEe4 genetic risk factor for AD in young adulthood, its relationship with cognition, and potential effects of other variables on the findings. While conventional volumetric analyses revealed no consistent differences, more sophisticated analyses identified subtle structural differences between APOEe4 carriers and non-carriers. Findings from diffusion studies were limited, but functional studies demonstrated consistent alterations in connectivity and activity. The complex relationship between APOE genotype, neuroimaging variables, and cognition revealed no consensus on the directionality of findings. Methodological choices, including analytical approaches, sample size, and the influence of other genes, gender, and ethnicity, varied across studies, impacting comparability and generalizability. Recommendations for future research include multimodal and longitudinal imaging, standardisation of pipelines, advanced analytical techniques, and collaborative data pooling.

Associations between brain structure and dual decline in gait and cognition

Dual decline in gait and cognition is associated with an increased risk of dementia, with combined gait and memory decline exhibiting the strongest association. To better understand the underlying pathology, we investigated the associations of baseline brain structure with dual decliners using three serial gait speed and cognitive assessments in memory, processing speed-attention, and verbal fluency. Participants (n=267) were categorized based on annual decline in gait speed and cognitive measures. Lower gray and white matter volume and higher white matter hyperintensity volume increased the risk of being a dual decliner in gait and both the memory and processing speed-attention groups (all p < 0.05). Lower hippocampal volume (p = 0.047) was only associated with dual decline in gait and memory group. No brain structures were correlated with dual decline in gait and verbal fluency. These results suggest that neurodegenerative pathology and white matter hyperintensities are involved in dual decline in gait and both memory and processing speed-attention. Smaller hippocampal volume may only contribute to dual decline in gait and memory.

Safety and efficacy of sodium benzoate for patients with mild Alzheimer's disease: a systematic review and meta-analysis

OBJECTIVE

Alzheimer's disease (AD) is the most common neurodegenerative disorder. A key factor in its pathogenesis is the dysfunction of the N-methyl-D-aspartate (NMDA) receptor due to D-serine degradation by D-amino acid oxidase. Benzoate has been suggested to enhance NMDA receptor function, potentially benefiting early-phase AD. This study aimed to synthesize evidence from randomized clinical trials (RCTs) on the safety and efficacy of sodium benzoate in AD patients.

METHODS

We followed PRISMA statement guidelines during the accommodation of this systematic review and meta-analysis. A computer literature search (PubMed, Scopus, Web of Science, and Cochrane Central) was conducted. We included RCTs that compared sodium benzoate with placebo regarding cognitive functions. The primary outcome measure was the Alzheimer's disease assessment scale-cognitive subscale, pooled as the mean difference between the two groups from baseline to the endpoint. The secondary outcomes measures are the clinician's interview-based impression of change plus caregiver input, catalase, and superoxide dismutase antioxidants.

RESULTS

Three RCTs (described in four articles) with 306 patients were included in this study. Sodium benzoate significantly improved the ADAS-cog score compared with placebo (MD -2.13 points, 95% CI [-3.35 to -0.90]; P= 0.0007).

CONCLUSION

Sodium benzoate is a safe drug that may improve cognitive function in patients with early-stage Alzheimer's disease. However, the significant effect arises primarily from one small study, highlighting the need for caution in interpretation. Further research with larger sample sizes and longer durations is necessary to validate these findings and assess safety and efficacy.

Hippocampal fimbria atrophy and its mediating effect between cerebral small vessel disease and cognitive impairment

We aimed to investigate the relationship between the volume reduction in hippocampal (HP) subregions and cognitive impairment in patients with cerebral small vessel disease (CSVD). Clinical, cognitive, and magnetic resonance imaging data were obtained for 315 participants. The CSVD group included 146 participants with a total CSVD score of 1-4. 169 participants with a total CSVD score of zero were used as control group (CSVD-0). The volume differences of 19 HP subregions between CSVD and CSVD-0 groups were analyzed, and we investigated the hazard factors that might cause subregional volume reduction in HP. Mediation analysis was performed to detect the relationship among HP subregional volumes, CSVD burden, and cognitive function. In our results, significant differences can be found in the volumes of CA4 body, presubiculum-head, presubiculum-body, subiculum-body, GC-ML-DG-head, GC-ML-DG-body, fimbria, and HP tail between CSVD group and control group. Regression analysis showed that fimbria was the most impacted HP subregion by CSVD. And mediation analysis revealed fimbria volume was a mediator variable between total CSVD score and MoCA/SCWT score. These results suggest that the volumes of HP subregions, especially the fimbria, may be effective potential biomarkers for early detecting cognitive impairment in CSVD.

Aging of Krushinsky-Molodkina audiogenic rats is accompanied with pronounced neurodegeneration and dysfunction of the glutamatergic system in the hippocampus

Advancing age strongly correlates with an increased risk of epilepsy development. On the other hand, epilepsy may exacerbate the negative effects of aging making it pathological. In turn, the possible link between aging and epileptogenesis is dysregulation of glutamatergic transmission. In the present study, we analyzed the functional state of the glutamatergic system in the hippocampus of aging (18-month-old) Krushinsky-Molodkina (KM) audiogenic rats to disclose alterations associated with aging on the background of inherited predisposition to audiogenic seizures (AGS). Naïve KM rats with no AGS experience were recruited in the experiments. Wistar rats of the corresponding age were used as a control. First of all, aging KM rats demonstrated a significant decrease in cell population and synaptopodin expression in the hippocampus indicating enhanced loss of cells and synapses. Meanwhile, elevated phosphorylation of ERK1/2 and CREB and increased glutamate in the neuronal perikarya were revealed indicating increased activity of the rest hippocampal cells and increased glutamate production. However, glutamate in the fibers and synapses was mainly unchanged, and the proteins regulating glutamate exocytosis showed variable changes which could compensate each other and maintain glutamate release at the unchanged level. In addition, we revealed downregulation of NMDA-receptor subunit GluN2B and upregulation of AMPA-receptor GluA2 subunit, which could also prevent overexcitation and support cell survival in the hippocampus of aging KM rats. Nevertheless, abnormally high glutamate production, observed in aging KM rats, may provide the basis for hyperexcitability of the hippocampus and increased seizure susceptibility in old age.

Unveiling the hippocampal subfield changes across the Alzheimer's disease continuum: a systematic review of neuroimaging studies

Studies exploring the hippocampal subfield atrophy in Alzheimer's disease (AD) have shown contradictory results. This review aims to disentangle such heterogeneity by investigating the dynamic changes of hippocampal subfields across the AD continuum. We systematically searched the PubMed and EMBASE databases for case-control studies. Selected studies included investigations of biomarker-based amyloid status and reported data on hippocampal subfield atrophy using advanced MRI techniques. Twelve studies were included. Despite high heterogeneity, a distinguishable pattern of vulnerability of hippocampal subfields can be recognized from the cognitively unimpaired phase to the dementia stage, shedding light on hippocampal changes with disease progression. Consistent findings revealed atrophy in the subiculum and presubiculum, along with a potential increase in volume in the cornu ammonis (CA) among the cognitively unimpaired group, a feature not observed in patients experiencing subjective cognitive decline. Atrophy in the subiculum, presubiculum, CA 1-4, and the dentate gyrus characterized the mild cognitive impairment stage, with a more pronounced severity in the progression to dementia.

Exploring temporal and sex-linked dysregulation in Alzheimer disease phosphoproteome

This study aims to characterize dysregulation of phosphorylation for the 5XFAD mouse model of Alzheimer disease (AD). Employing global phosphoproteome measurements, we analyze temporal (3, 6, and 9 months) and sex-dependent effects on mouse hippocampus tissue to unveil molecular signatures associated with AD initiation and progression. Our findings reveal consistent phosphorylation of known AD biomarkers APOE and GFAP in 5XFAD mice, alongside candidates BIG3, CLCN6, and STX7, suggesting their potential as biomarkers for AD pathology. In addition, we identify PDK1 as a significantly dysregulated kinase at 9 months in females, and the regulation of gap junction activity as a key pathway associated with Alzheimer disease across all time points. AD-Xplorer, the interactive browser of our dataset, enables exploration of AD-related changes in phosphorylation, protein expression, kinase activities, and pathways. AD-Xplorer aids in biomarker discovery and therapeutic target identification, emphasizing temporal and sex-specific nature of significant phosphoproteomic signatures. Available at: https://yilmazs.shinyapps.io/ADXplorer.

Hippocampal tau-induced GRIN3A deficiency in Alzheimer's disease

Alzheimer's disease (AD) is characterized by significant alterations in hippocampal function and structure, but the molecular mechanisms underlying the hippocampal region remain elusive. We integrated multiple transcriptome datasets including human or rat hippocampus (GSE173955, GSE129051, GSE84422) to identify candidate genes. Subsequent analyses including gene ontology analysis and protein-protein interaction mapping were performed to identify key genes and pathways. We found that glutamate ionotropic receptor NMDA-type subunit 3A (GRIN3A) and glutamate metabotropic receptor 8 (GRM8), which are related to the glutamatergic system, were the top two annotated genes and directly related to MAPT, which encodes a tau protein. Since there is no direct evidence of interaction between tauopathy and these genes in AD, further transcriptomic data (GSE125957, GSE56772) from tau transgenic mice and experimental validations through primary rat hippocampal neurons and induced pluripotent stem cell (iPSC)-derived brain organoids were performed. Interestingly, we identified that decreased NR3A (encoded by GRIN3A) and mGluR8 (encoded by GRM8) are correlated with tauopathy and loss of postsynaptic function in AD. Taken together, our results identified a novel tauopathy biomarker GRIN3A in AD. Furthermore, our findings suggest that an integrated approach combining public databases and diverse experimental validations can contribute to the advancement of precision medicine therapies.

Treatment with Blackberry Extract and Metformin in Sporadic Alzheimer's Disease Model: Impact on Memory, Inflammation, Redox Status, Phosphorylated Tau Protein and Insulin Signaling

Natural products offer promising potential for the development of new therapies for Alzheimer's disease (AD). Blackberry fruits are rich in phytochemical compounds capable of modulating pathways involved in neuroprotection. Additionally, drug repurposing and repositioning could also accelerate the development of news treatments for AD. In light of the reduced brain glucose metabolism in AD, an alternative approach has been the use of the drug metformin. Thus, the aim of this study was to evaluate the effect of treatment with blackberry extract in a model of AD induced by streptozotocin (STZ) and compare it with metformin treatment. Male rats were divided into groups: I - Control; II - STZ; III - STZ + blackberry extract (100 mg/kg); IV - STZ + blackberry extract (200 mg/kg) and V - STZ + metformin (150 mg/kg). The animals received intracerebroventricular injection of STZ or buffer. Seven days after the surgical procedure, the animals were treated orally with blackberry extract or metformin for 21 days. Blackberry extract and metformin prevented the memory impairment induced by STZ. In animals of group II, an increase in acetylcholinesterase activity, phosphorylated tau protein, IL-6, oxidative damage, and gene expression of GSK-3β and Nrf2 was observed in the hippocampus. STZ induced a decrease in IL-10 levels and down-regulated the gene expression of Akt1, IRS-1 and FOXO3a. Blackberry extract and metformin prevented the alterations in acetylcholinesterase activity, IL-6, GSK3β, Nrf2, and oxidative damage. In conclusion, blackberry extract exhibits multi-target actions in a model of AD, suggesting new therapeutic potentials for this neurodegenerative disease.

Investigating the Impact of Intracerebroventricular Streptozotocin on Female Rats with and without Ovaries: Implications for Alzheimer's Disease

To contribute to research on female models of Alzheimer's disease (AD), our aim was to study the effect of intracerebroventricular (ICV) injection of streptozotocin (STZ) in female rats, and to evaluate a potential neuroprotective action of ovarian steroids against STZ. Female rats were either ovariectomized (OVX) or kept with ovaries (Sham) two weeks before ICV injections. Animals were injected with either vehicle (artificial cerebrospinal fluid, aCSF) or STZ (3 mg/kg) and separated into four experimental groups: Sham + aCSF, Sham + STZ, OVX + aCSF and OVX + STZ. Nineteen days post-injection, we assessed different behavioral aspects: burying, anxiety and exploration, object recognition memory, spatial memory, and depressive-like behavior. Immunohistochemistry and Immunoblot analyses were performed in the hippocampus to examine changes in AD-related proteins and neuronal and microglial populations. STZ affected burying and exploratory behavior depending on ovarian status, and impaired recognition but not spatial memory. STZ and ovariectomy increased depressive-like behavior. Interestingly, STZ did not alter the expression of β-amyloid peptide or Tau phosphorylated forms. STZ affected the neuronal population from the Dentate Gyrus, where immature neurons were more vulnerable to STZ in OVX rats. Regarding microglia, STZ increased reactive cells, and the OVX + STZ group showed an increase in the total cell number. In sum, STZ partially affected female rats, compared to what was previously reported for males. Although AD is more frequent in women, reports about the effect of ICV-STZ in female rats are scarce. Our work highlights the need to deepen into the effects of STZ in the female brain and study possible sex differences.

Enhanced hippocampal TIAM2S expression alleviates cognitive deficits in Alzheimer's disease model mice

BACKGROUND

Dendritic spine dysfunction is a key feature of Alzheimer's disease (AD) pathogenesis. Human T-cell lymphoma invasion and metastasis 2 (TIAM2) is expressed in two isoforms, the full length (TIAM2L) and a short transcript (TIAM2S). Compared to TIAM2L protein, which is undetectable, TIAM2S protein is abundant in human brain tissue, especially the hippocampus, and can promote neurite outgrowth in our previous findings. However, whether enhanced hippocampal TIAM2S expression can alleviate cognitive deficits in Alzheimer's disease model mice remains unclear.

METHODS

We crossbred 3xTg-AD with TIAM2S mice to generate an AD mouse model that carries the human TIAM2S gene (3xTg-AD/TIAM2S mice). The Morris water maze and object location tests assessed hippocampus-dependent spatial memory. Lentiviral-driven shRNA or cDNA approaches were used to manipulate hippocampal TIAM2S expression. Golgi staining and Sholl analysis were utilized to measure neuronal dendrites and dendritic spines in the mouse hippocampi.

RESULTS

Compared to 3xTg-AD mice, 3xTg-AD/TIAM2S mice displayed improved cognitive functions. According to the hippocampus is one of the earliest affected brain regions by AD, we further injected TIAM2S shRNA or TIAM2S cDNA into mouse hippocampi to confirm whether manipulating hippocampal TIAM2S expression could affect AD-related cognitive functions. The results showed that the reduced hippocampal TIAM2S expression in 3xTg-AD/TIAM2S mice abolished the memory improvement effect, whereas increased hippocampal TIAM2S levels alleviated cognitive deficits in 3xTg-AD mice. Furthermore, we found that TIAM2S-mediated memory improvement was achieved by regulating dendritic plasticity.

CONCLUSIONS

These results will provide new insights into connecting TIAM2S with AD and support the notion that TIAM2S should be investigated as potential AD therapeutic targets.

Transformer-based approaches for neuroimaging: an in-depth review of their role in classification and regression tasks

In the ever-evolving landscape of deep learning (DL), the transformer model emerges as a formidable neural network architecture, gaining significant traction in neuroimaging-based classification and regression tasks. This paper presents an extensive examination of transformer's application in neuroimaging, surveying recent literature to elucidate its current status and research advancement. Commencing with an exposition on the fundamental principles and structures of the transformer model and its variants, this review navigates through the methodologies and experimental findings pertaining to their utilization in neuroimage classification and regression tasks. We highlight the transformer model's prowess in neuroimaging, showcasing its exceptional performance in classification endeavors while also showcasing its burgeoning potential in regression tasks. Concluding with an assessment of prevailing challenges and future trajectories, this paper proffers insights into prospective research directions. By elucidating the current landscape and envisaging future trends, this review enhances comprehension of transformer's role in neuroimaging tasks, furnishing valuable guidance for further inquiry.

β-Amyloids and Immune Responses Associated with Alzheimer's Disease

Alzheimer's disease (AD) is associated with the accumulation of β-amyloids (Aβs) and the formation of Aβ plaques in the brain. Various structural forms and isoforms of Aβs that have variable propensities for oligomerization and toxicity and may differentially affect the development of AD have been identified. In addition, there is evidence that β-amyloids are engaged in complex interactions with the innate and adaptive immune systems, both of which may also play a role in the regulation of AD onset and progression. In this review, we discuss what is currently known about the intricate interplay between β-amyloids and the immune response to Aβs with a more in-depth focus on the possible roles of B cells in the pathogenesis of AD.

Physical Exercise and Mechanism Related to Alzheimer's Disease: Is Gut-Brain Axis Involved?

BACKGROUND

Alzheimer's disease is a progressive neurodegenerative disease characterized by structural changes in the brain, including hippocampal atrophy, cortical thinning, amyloid plaques, and tau tangles. Due to the aging of the global population, the burden of Alzheimer's disease is expected to increase, making the exploration of non-pharmacological interventions, such as physical exercise, an urgent priority.

RESULTS

There is emerging evidence that regular physical exercise may mitigate the structural and functional declines associated with Alzheimer's disease. The underlying mechanisms, however, remain poorly understood. Gut-brain axis research is a promising area for further investigation. This system involves bidirectional communication between the gut microbiome and the brain. According to recent studies, the gut microbiome may influence brain health through modulating neuroinflammation, producing neuroactive compounds, and altering metabolic processes. Exercise has been shown to alter the composition of the gut microbiome, potentially impacting brain structure and function. In this review, we aim to synthesize current research on the relationship between physical exercise, structural brain changes in Alzheimer's disease, and the gut-brain axis.

CONCLUSIONS

In this study, we will investigate whether changes in the gut microbiome induced by physical exercise can mediate its neuroprotective effects, offering new insights into the prevention and treatment of Alzheimer's disease. By integrating findings from neuroimaging studies, clinical trials, and microbiome research, this review will highlight potential mechanisms. It will also identify key gaps in the literature. This will pave the way for future research directions.

Photobiomodulation regulates astrocyte activity and ameliorates scopolamine-induced cognitive behavioral decline

Introduction

The pathophysiological mechanism of Alzheimer's disease (AD) has not been clearly identified, and effective treatment methods have not yet been established. Scopolamine causes cholinergic dysfunction in the brain, including the accumulation of amyloid-beta plaques, thereby increasing oxidative stress and neuroinflammation, mimicking AD. Glial cells such as astrocytes have recently been identified as possible biomarkers for AD. Photobiomodulation (PBM) elicits a beneficial biological response in cells and tissues. PBM effects on the central nervous system (CNS) have been widely researched, including effects on astrocyte activity.

Methods

In the present study, PBM was performed using light at the near-infrared wavelength of 825 nm. The Morris water maze and Y-maze tests were employed to evaluate cognitive function decline in a scopolamine-induced memory dysfunction model and its improvement with PBM. In addition, alteration of the mitogen-activated protein kinase (MAPK) pathway and immunofluorescence expression levels of active astrocytes were observed in the hippocampus, which is one of the areas affected by AD, to evaluate the mechanism of action of PBM.

Results

A reduction in the neuronal cell death in the hippocampus caused by scopolamine was observed with PBM. Moreover, alteration of a MAPK pathway-related marker and changes in glial fibrillary acidic protein (an active astrocyte marker) expression were observed in the PBM-treated group. Finally, significant correlations between functional and histological results were found, validating the results.

Discussion

These findings indicate the possibility of behavioral and histological improvement due to PBM in scopolamine-induced CNS alteration, which mimics AD. This improvement could be related to neuroinflammatory modulation and altered astrocyte activity.

Mesenchymal Stem Cell-Derived Exosomes as a Neuroregeneration Treatment for Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) is the most prevalent kind of dementia and is a long-term degenerative disease. Pathologically, it is defined by the development of extracellular amyloid-β plaques and intracellular neurofibrillary tangles made up of hyperphosphorylated tau protein. This causes neuronal death, particularly in the hippocampus and cortex. Mesenchymal stem cell (MSC)-derived exosomes have been identified as possibly therapeutic and have promise for Alzheimer's disease due to their regenerative characteristics.

METHODS

A systematic retrieval of information was performed on PubMed. A total of 60 articles were found in a search on mesenchymal stem cells, exosomes, and Alzheimer's disease. A total of 16 ongoing clinical trials were searched and added from clinicaltrials.gov. We added 23 supporting articles to help provide information for certain sections. In total, we included 99 articles in this manuscript: 50 are review articles, 13 are preclinical studies, 16 are clinical studies, 16 are ongoing clinical trials, and 4 are observational studies. Appropriate studies were isolated, and important information from each of them was understood and entered into a database from which the information was used in this article. The clinical trials on mesenchymal stem cell exosomes for Alzheimer's disease were searched on clinicaltrials.gov.

RESULTS

Several experimental investigations have shown that MSC-Exo improves cognitive impairment in rats. In this review paper, we summarized existing understanding regarding the molecular and cellular pathways behind MSC-Exo-based cognitive function restoration, with a focus on MSC-Exo's therapeutic potential in the treatment of Alzheimer's disease.

CONCLUSION

AD is a significant health issue in our culture and is linked to several important neuropathological characteristics. Exosomes generated from stem cells, such as mesenchymal stem cells (MSCs) or neural stem cells (NSCs), have been examined more and more in a variety of AD models, indicating that they may be viable therapeutic agents for the treatment of diverse disorders. Exosome yields may be increased, and their therapeutic efficacy can be improved using a range of tailored techniques and culture conditions. It is necessary to provide standardized guidelines for exosome manufacture to carry out excellent preclinical and clinical research.

Modulation of Amyloid and Tau Aggregation to Alleviate Cognitive Impairment in a Transgenic Mouse Model of Alzheimer's Disease

Aggregation of misfolded amyloid-β (Aβ) and hyperphosphorylated tau proteins to plaques and tangles, respectively, is the major drug target of Alzheimer's disease (AD), as the former is an onset biomarker and the latter is associated with neurodegeneration. Thus, we report a small molecule drug candidate, DN5355, with a dual-targeting function toward aggregates of both Aβ and tau. DN5355 was selected through a series of four screenings assessing 52 chemicals for their functions to inhibit and reverse the aggregation of Aβ and tau by utilizing thioflavin T. When orally administered to AD transgenic mouse model 5XFAD, DN5355 significantly reduced cerebral Aβ plaques and hyperphosphorylated tau tangles. In Y-maze spontaneous alteration and contextual fear conditioning tests, 5XFAD mice showed amelioration of cognitive deficits upon the oral administration of DN5355.

Alzheimer's Disease Pathology and Assistive Nanotheranostic Approaches for Its Therapeutic Interventions

Alzheimer's disease (AD) still prevails and continues to increase indiscriminately throughout the 21st century, and is thus responsible for the depreciating quality of health and associated sectors. AD is a progressive neurodegenerative disorder marked by a significant amassment of beta-amyloid plaques and neurofibrillary tangles near the hippocampus, leading to the consequent loss of cognitive abilities. Conventionally, amyloid and tau hypotheses have been established as the most prominent in providing detailed insight into the disease pathogenesis and revealing the associative biomarkers intricately involved in AD progression. Nanotheranostic deliberates rational thought toward designing efficacious nanosystems and strategic endeavors for AD diagnosis and therapeutic implications. The exceeding advancements in this field enable the scientific community to envisage and conceptualize pharmacokinetic monitoring of the drug, sustained and targeted drug delivery responses, fabrication of anti-amyloid therapeutics, and enhanced accumulation of the targeted drug across the blood-brain barrier (BBB), thus giving an optimistic approach towards personalized and precision medicine. Current methods idealized on the design and bioengineering of an array of nanoparticulate systems offer higher affinity towards neurocapillary endothelial cells and the BBB. They have recently attracted intriguing attention to the early diagnostic and therapeutic measures taken to manage the progression of the disease. In this article, we tend to furnish a comprehensive outlook, the detailed mechanism of conventional AD pathogenesis, and new findings. We also summarize the shortcomings in diagnostic, prognostic, and therapeutic approaches undertaken to alleviate AD, thus providing a unique window towards nanotheranostic advancements without disregarding potential drawbacks, side effects, and safety concerns.

Nucleoporin 153 deficiency in adult neural stem cells defines a pathological protein-network signature and defective neurogenesis in a mouse model of AD

BACKGROUND

Reduction of adult hippocampal neurogenesis is an early critical event in Alzheimer's disease (AD), contributing to progressive memory loss and cognitive decline. Reduced levels of the nucleoporin 153 (Nup153), a key epigenetic regulator of NSC stemness, characterize the neural stem cells isolated from a mouse model of AD (3×Tg) (AD-NSCs) and determine their altered plasticity and gene expression.

METHODS

Nup153-regulated mechanisms contributing to NSC function were investigated: (1) in cultured NSCs isolated from AD and wild type (WT) mice by proteomics; (2) in vivo by lentiviral-mediated delivery of Nup153 or GFP in the hippocampus of AD and control mice analyzing neurogenesis and cognitive function; (3) in human iPSC-derived brain organoids obtained from AD patients and control subjects as a model of neurodevelopment.

RESULTS

Proteomic approach identified Nup153 interactors in WT- and AD-NSCs potentially implicated in neurogenesis regulation. Gene ontology (GO) analysis showed that Nup153-bound proteins in WT-NSCs were involved in RNA metabolism, nuclear import and epigenetic mechanisms. Nup153-bound proteins in AD-NSCs were involved in pathways of neurodegeneration, mitochondrial dysfunction, proteasomal processing and RNA degradation. Furthermore, recovery of Nup153 levels in AD-NSCs reduced the levels of oxidative stress markers and recovered proteasomal activity. Lentiviral-mediated delivery of Nup153 in the hippocampal niche of AD mice increased the proliferation of early progenitors, marked by BrdU/DCX and BrdU/PSANCAM positivity and, later, the integration of differentiating neurons in the cell granule layer (BrdU/NeuN+ cells) compared with GFP-injected AD mice. Consistently, Nup153-injected AD mice showed an improvement of cognitive performance in comparison to AD-GFP mice at 1 month after virus delivery assessed by Morris Water Maze. To validate the role of Nup153 in neurogenesis we took advantage of brain organoids derived from AD-iPSCs characterized by fewer neuroepithelial progenitor loops and reduced differentiation areas. The upregulation of Nup153 in AD organoids recovered the formation of neural-like tubes and differentiation.

CONCLUSIONS

Our data suggest that the positive effect of Nup153 on neurogenesis is based on a complex regulatory network orchestrated by Nup153 and that this protein is a valuable disease target.

Hyperglycemia and cognitive impairments anticipate the onset of an overt type 2 diabetes-like phenotype in TALLYHO/JngJ mice

Type 2 Diabetes mellitus (T2DM) is a metabolic disorder characterized by chronic hyperglycemia, resulting from deficits in insulin secretion, insulin action, or both. Whilst the role of insulin in the peripheral nervous system has been ascertained in countless studies, its role in the central nervous system (CNS) is emerging only recently. Brain insulin has been lately associated with brain disorders like Alzheimer's disease, obsessive compulsive disorder, and attention deficit hyperactivity disorder. Thus, understanding the role of insulin as a common risk factor for mental and somatic comorbidities may disclose novel preventative and therapeutic approaches. We evaluated general metabolism (glucose tolerance, insulin sensitivity, energy expenditure, lipid metabolism, and polydipsia) and cognitive capabilities (attention, cognitive flexibility, and memory), in adolescent, young adult, and adult male and female TALLYHO/JngJ mice (TH, previously reported to constitute a valid experimental model of T2DM due to impaired insulin signaling). Adult TH mice have also been studied for alterations in gut microbiota diversity and composition. While TH mice exhibited profound deficits in cognitive flexibility and altered glucose metabolism, we observed that these alterations emerged either much earlier (males) or independent of (females) a comprehensive constellation of symptoms, isomorphic to an overt T2DM-like phenotype (insulin resistance, polydipsia, higher energy expenditure, and altered lipid metabolism). We also observed significant sex-dependent alterations in gut microbiota alpha diversity and taxonomy in adult TH mice. Deficits in insulin signaling may represent a common risk factor for both T2DM and CNS-related deficits, which may stem from (partly) independent mechanisms.

Restoration of Spatial Learning Through Oral Administration of Lipopolysaccharides in Diabetes-related Cognitive Dysfunction

BACKGROUND/AIM

In a previous report, our group showed that oral administration of lipopolysaccharides (LPS) from Pantoea agglomerans can prevent the progression of streptozotocin (STZ)-induced diabetes-related cognitive dysfunction (DRCD) in mice without causing significant side-effects. However, the treatment effects of oral administration of LPS to DRCD remain unknown.

MATERIALS AND METHODS

We modified our previous animal experimental model to investigate whether oral administration of LPS can recover cognitive function after DRCD onset.

RESULTS

The Morris water maze (MWM) revealed a significant decrease in learning and memory abilities at 13 days after intracerebroventricular administration of STZ, thereby providing evidence of the occurrence of DRCD in the animal model. Oral administration of LPS (1 mg/kg per day) started after cognitive impairment was observed. After 28 days of treatment, mice receiving LPS via the oral route showed significant recovery of spatial learning ability, a symptom of early dementia, while only a trend toward recovery was seen for spatial memory compared to the untreated group.

CONCLUSION

These results, limited to MWM, suggest that oral administration of LPS is a promising therapeutic strategy for restoring decreased spatial learning ability.

Impact of growth hormone-secreting pituitary adenoma on limbic system and its correlation with cognitive impairment

Purpose

To assess the quantitative gray matter volume of the limbic system in growth hormone-secreting pituitary adenoma (GHPAs) patients and its correlation to cognitive function.

Method

91 right-handed patients with pituitary adenomas were retrospectively included from the First Affiliated Hospital of Sun Yat-sen University -48 with GHPAs and 43 with non-functioning pituitary adenomas (NFPAs). Participants underwent serum hormone assessment, regular sellar MRI scanning with T1WI-MPRAGE. Cognitive function was gauged using MoCA and MMSE. Brain region auto-segmentation and gray matter volume calculation were conducted on the Brainsite platform.

Results

Compared to NFPAs patients, GHPAs patients had higher gray matter volume (758,285 vs 674,610 mm³, p < 0.001). No significant volumetric differences in both sides of limbic system gray matter while there were evident differences in the relative volumes of limbic system gray matter between groups. GHPAs patients scored lower on MOCA (24.0 (2.18) vs 25.1 (2.28), p < 0.031), with no difference in MMSE. We observed a significant correlation between the relative limbic volume and MOCA scales, while no evident correlation was found between relative limbic volume and serum hormone or tumor aggressiveness. Univariate and multivariate Logistic regression showed that hippocampus and limbic cortex (parahippocampal gyrus and internal olfactory area) of advantageous hemisphere correlated significantly with occurrence of mild cognitive impairment with the C-statistic reaching 0.90.

Conclusion

Patients with GHPAs show a relative decrease in limbic gray matter volume, especially in the hippocampus and limbic cortex of the dominant hemisphere, which is associated with mild cognitive impairment.

Quercetin ameliorates neuroinflammatory and neurodegenerative biomarkers in the brain and improves neurobehavioral parameters in a repeated intranasal amyloid-beta exposed model of Alzheimer's disease

Objectives: The aim of the present study was to study the potential therapeutic effects of quercetin in protection against repeated intranasal exposure of an amyloid-beta-induced mouse model. Methods: Mice received intranasal Aβ1-42 (5 μg/10 μL) exposure once daily for seven consecutive days. Quercetin was orally administered to them at 30 mg kg-1 and 100 mg kg-1 doses for one week starting from day five following Aβ1-42 peptide administration. Following this, the animals were evaluated for neurobehavioral parameters using a Morris water maze test and a novel object recognition test. Further to this, the biomarkers for neuroinflammation and neurodegeneration were evaluated in the hippocampus and cortex regions of the brain in these animals. Results: Multiple exposures to intranasal Aβ led to a significant decline in the learning and cognitive memory of the animals, whereas oral treatment with quercetin at dosages of 30 and 100 mg kg-1 alleviated Aβ-induced effects. Quercetin treatment significantly reduced Aβ accumulation, oxidative stress and proinflammatory cytokine biomarkers in the brain. In addition, it also alleviated the activation of astrocytic biomarkers, amyloid precursor protein and phosphorylated-tau proteins in the brain. Conclusion: Quercetin was found to be a potent antioxidant, anti-inflammatory compound with protection against neurodegenerative damage and improved learning and cognitive memory in a repeated Aβ-exposure model of AD.

Neuroanatomical and clinical factors predicting future cognitive impairment

Identifying cognitively normal (CN) older adults who will convert to cognitive impairment (CI) due to Alzheimer's disease is crucial for early intervention. Clinical and neuroimaging measures were acquired from 301 CN adults who converted to CI within 15 years of baseline, and 294 who did not. Regional volumes and brain age measures were extracted from T1-weighted magnetic resonance images. Linear discriminant analysis compared non-converters' characteristics against those of short-, mid-, and long-term converters. Conversion was associated with clinical measures such as hearing impairment and self-reported memory decline. Converters' brain volumes were smaller than non-converters' across 48 frontal, temporal, and subcortical structures. Brain age measures of 12 structures were correlated with shorter times to conversion. Conversion prediction accuracy increased from 81.5% to 90.5% as time to conversion decreased. Proximity to CI conversion is foreshadowed by anatomic features of brain aging that enhance the accuracy of predicting conversion.

Alzheimer's disease stage recognition from MRI and PET imaging data using Pareto-optimal quantum dynamic optimization

The threat posed by Alzheimer's disease (AD) to human health has grown significantly. However, the precise diagnosis and classification of AD stages remain a challenge. Neuroimaging methods such as structural magnetic resonance imaging (sMRI) and fluorodeoxyglucose positron emission tomography (FDG-PET) have been used to diagnose and categorize AD. However, feature selection approaches that are frequently used to extract additional data from multimodal imaging are prone to errors. This paper suggests using a static pulse-coupled neural network and a Laplacian pyramid to combine sMRI and FDG-PET data. After that, the fused images are used to train the Mobile Vision Transformer (MViT), optimized with Pareto-Optimal Quantum Dynamic Optimization for Neural Architecture Search, while the fused images are augmented to avoid overfitting and then classify unfused MRI and FDG-PET images obtained from the AD Neuroimaging Initiative (ADNI) and Open Access Series of Imaging Studies (OASIS) datasets into various stages of AD. The architectural hyperparameters of MViT are optimized using Quantum Dynamic Optimization, which ensures a Pareto-optimal solution. The Peak Signal-to-Noise Ratio (PSNR), the Mean Squared Error (MSE), and the Structured Similarity Indexing Method (SSIM) are used to measure the quality of the fused image. We found that the fused image was consistent in all metrics, having 0.64 SIMM, 35.60 PSNR, and 0.21 MSE for the FDG-PET image. In the classification of AD vs. cognitive normal (CN), AD vs. mild cognitive impairment (MCI), and CN vs. MCI, the precision of the proposed method is 94.73%, 92.98% and 89.36%, respectively. The sensitivity is 90. 70%, 90. 70%, and 90. 91% while the specificity is 100%, 100%, and 85. 71%, respectively, in the ADNI MRI test data.

Multiple Transcriptomic Analyses Explore Potential Synaptic Biomarker Rabphilin-3A for Alzheimer's Disease

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder afflicting the elderly population worldwide. The identification of potential gene candidates for AD holds promises for diagnostic biomarkers and therapeutic targets. Employing a comprehensive strategy, this study integrated transcriptomic data from diverse data sources, including microarray and single-cell datasets from blood and tissue samples, enabling a detailed exploration of gene expression dynamics. Through this thorough investigation, 19 notable candidate genes were found with consistent expression changes across both blood and tissue datasets, suggesting their potential as biomarkers for AD. In addition, single cell sequencing analysis further highlighted their specific expression in excitatory and inhibitory neurons, the primary functional units in the brain, underscoring their relevance to AD pathology. Moreover, the functional enrichment analysis revealed that three of the candidate genes were downregulated in synaptic signaling pathway. Further validation experiments significantly showed reduced levels of rabphilin-3A (RPH3A) in 3xTg-AD model mice, implying its role in disease pathogenesis. Given its role in neurotransmitter exocytosis and synaptic function, further investigation into RPH3A and its interactions with neurotrophic proteins may provide valuable insights into the complex molecular mechanisms underlying synaptic dysfunction in AD.

Association of glycosylated hemoglobin concentrations with structural and functional brain changes in the normoglycemic population: A systematic review

Optimal glucose control is crucial for maintaining brain health and preventing metabolic and cognitive disorders in the general population. Glycosylated hemoglobin (HbA1c) serves as a key marker for assessing glucose intolerance and its impact on brain structure and function in healthy individuals. However, existing literature presents conflicting findings, necessitating a systematic review to consolidate current knowledge in this domain. This systematic review examines 26 English-language studies involving participants aged 15 years and above, investigating the relationship between HbA1c levels and brain health. Studies focusing on normal/general populations and utilizing magnetic resonance imaging (MRI) as the imaging modality were included. Exclusion criteria encompassed review articles, abstracts, letters, animal studies, and research involving neuropsychiatric or metabolic diseases. Data were gathered from PubMed, Scopus, and Web of Science databases up to November 2023. Analysis reveals significant associations between HbA1c levels and various brain metrics, including volume, cortical thickness, fractional anisotropy, mean diffusivity, activity, and connectivity. However, findings exhibit inconsistency, likely attributed to disparities in sample characteristics and study sizes. Notably, hippocampal volume, white matter hyperintensity, and ventral attention network connectivity emerge as frequently affected structures and functions, mirroring trends observed in diabetic populations. Despite inconclusive evidence, glucose intolerance appears to exert considerable influence on select brain structures and functions in individuals without diagnosed metabolic disorders. Understanding these associations is critical for mitigating the risk of cognitive decline and dementia in healthy populations. Future investigations should aim to elucidate the intricate relationship between HbA1c concentrations and brain health parameters in normoglycemic individuals.

Latent diffusion model-based MRI superresolution enhances mild cognitive impairment prognostication and Alzheimer's disease classification

INTRODUCTION

Timely diagnosis and prognostication of Alzheimer's disease (AD) and mild cognitive impairment (MCI) are pivotal for effective intervention. Artificial intelligence (AI) in neuroradiology may aid in such appropriate diagnosis and prognostication. This study aimed to evaluate the potential of novel diffusion model-based AI for enhancing AD and MCI diagnosis through superresolution (SR) of brain magnetic resonance (MR) images.

METHODS

1.5T brain MR scans of patients with AD or MCI and healthy controls (NC) from Alzheimer's Disease Neuroimaging Initiative 1 (ADNI1) were superresolved to 3T using a novel diffusion model-based generative AI (d3T*) and a convolutional neural network-based model (c3T*). Comparisons of image quality to actual 1.5T and 3T MRI were conducted based on signal-to-noise ratio (SNR), naturalness image quality evaluator (NIQE), and Blind/Referenceless Image Spatial Quality Evaluator (BRISQUE). Voxel-based volumetric analysis was then conducted to study whether 3T* images offered more accurate volumetry than 1.5T images. Binary and multiclass classifications of AD, MCI, and NC were conducted to evaluate whether 3T* images offered superior AD classification performance compared to actual 1.5T MRI. Moreover, CNN-based classifiers were used to predict conversion of MCI to AD, to evaluate the prognostication performance of 3T* images. The classification performances were evaluated using accuracy, sensitivity, specificity, F1 score, Matthews correlation coefficient (MCC), and area under the receiver-operating curves (AUROC).

RESULTS

Analysis of variance (ANOVA) detected significant differences in image quality among the 1.5T, c3T*, d3T*, and 3T groups across all metrics. Both c3T* and d3T* showed superior image quality compared to 1.5T MRI in NIQE and BRISQUE with statistical significance. While the hippocampal volumes measured in 3T* and 3T images were not significantly different, the hippocampal volume measured in 1.5T images showed significant difference. 3T*-based AD classifications showed superior performance across all performance metrics compared to 1.5T-based AD classification. Classification performance between d3T* and actual 3T was not significantly different. 3T* images offered superior accuracy in predicting the conversion of MCI to AD than 1.5T images did.

CONCLUSIONS

The diffusion model-based MRI SR enhances the resolution of brain MR images, significantly improving diagnostic and prognostic accuracy for AD and MCI. Superresolved 3T* images closely matched actual 3T MRIs in quality and volumetric accuracy, and notably improved the prediction performance of conversion from MCI to AD.

Outcome of resveratrol and resveratrol with donepezil combination on the β-amyloid plaques and neurofibrillary tangles in Alzheimer's disease

The goal of this research was to study the effect of different doses of resveratrol (RS) and RS with donepezil (DPZ) on the deposition of amyloid beta (Aβ) and neurofibrillary tangles (NFTs) in colchicine-induced Alzheimer's disease (AD) brain. The study included three months old male Albino Wistar rats and consisted of six animal groups: AD model (group 1), treatment groups, RS 10 mg/kg body weight (group 2), RS 20 mg/kg body weight (group 3), RS 10 mg/kg body weight along with DPZ 1 mg/kg body weight (group 6), prophylaxis groups, RS 10 mg/kg body weight (group 4) and RS 20 mg/kg body weight (group 5). In the treatment groups, RS was given for 7 consecutive days from the day of induction of AD, and in the prophylaxis groups, we started RS 7 days even before the induction of AD and continued for seven days after the induction. The number of Aβs and NFTs at the frontal region, cornu ammonis (CA) 1,2,3,4 and dentate gyrus regions of hippocampus were evaluated. The immunohistochemical analysis was performed by using mouse anti-β-amyloid antibody for the Aβ plaques and polyclonal rabbit anti-human tau for the tau-positive neurons. The present study observed the accumulation of Aβ plaques and tau-positive neurons in the AD model. However, their numbers were significantly decreased in the treatment groups (p < 0.001). The best results were observed when RS 10 mg was given prophylactically (p < 0.01) and RS along with DPZ (p < 0.001), suggesting the neuroprotective effect of RS and its synergistic effect with the DPZ.

Traffic-related air pollution and APOE4 can synergistically affect hippocampal volume in older women: new findings from UK Biobank

A growing research body supports the connection between neurodegenerative disorders, including Alzheimer's disease (AD), and traffic-related air pollution (TRAP). However, the underlying mechanisms are not well understood. A deeper investigation of TRAP effects on hippocampal volume (HV), a major biomarker of neurodegeneration, may help clarify these mechanisms. Here, we explored TRAP associations with the HV in older participants of the UK Biobank (UKB), taking into account the presence of APOE e4 allele (APOE4), the strongest genetic risk factor for AD. Exposure to TRAP was approximated by the distance of the participant's main residence to the nearest major road (DNMR). The left/right HV was measured by magnetic resonance imaging (MRI) in cubic millimeters (mm3). Analysis of variance (ANOVA), Welch test, and regression were used to examine statistical significance. We found significant interactions between DNMR and APOE4 that influenced HV. Specifically, DNMR <50m (equivalent of a chronically high exposure to TRAP), and carrying APOE4 were synergistically associated with a significant (P = 0.01) reduction in the right HV by about 2.5% in women aged 60-75 years (results for men didn't reach a statistical significance). Results of our study suggest that TRAP and APOE4 jointly promote neurodegeneration in women. Living farther from major roads may help reduce the risks of neurodegenerative disorders, including AD, in female APOE4 carriers.

Cholecalciferol Supplementation Impacts Behavior and Hippocampal Neuroglial Reorganization in Vitamin D-Deficient Rats

Vitamin D deficiency (VDD) is widespread around the world and has been extensively documented to affect various health conditions, including the cognitive functioning of the brain. Serum 25-hydroxylated forms of vitamin D are traditionally used to determine vitamin D status. However, there is now evidence that cholecalciferol activation can occur and be controlled by locally expressed enzymes in the brain. This study aimed to investigate the effects of cholecalciferol supplementation on cognitive function in rats who underwent transient VDD in adulthood. Thirty-six adult Wistar rats were administered paricalcitol (seven doses of 32 ng injected every other day) along with a "vitamin D-free" diet to induce VDD, which was confirmed using a LC-MS/MS serum analysis of the cholecalciferol and 25-hydroxyvitamin D3 levels. Treatment was performed by including 1000 IU/kg and 10,000 IU/kg cholecalciferol in the diet. Cognitive performance was evaluated using the novel object recognition (NOR), Morris water maze (MWM), and radial arm maze (RAM) tests. An immunohistochemical analysis of the brain regions involved in learning and memory was performed by quantifying the neurons, astrocytes, and microglia labelled with anti-neuronal nuclei (NeuN), glial fibrillary acidic protein (GFAP), and ionized calcium-binding adaptor molecule 1 (Iba-1) antibodies, respectively. The vitamin D deficient group showed the lowest performance in both the MWM and RAM tests. In contrast, the cholecalciferol-treated groups exhibited a faster learning curve. However, no difference was detected between the groups in the NOR test. On the other hand, differences in the cellular organization of the hippocampus and amygdala were observed between the groups. Cholecalciferol supplementation decreased the density of the Iba-1- and GFAP-labeled cells in the hilus and cornu Ammonis 3 (CA3) regions of the hippocampus and in the amygdala. These results support vitamin D's substantial role in learning and memory. They also highlight that subtle changes of cognitive function induced by transient VDD could be reversed by cholecalciferol supplementation. Further studies are needed to better understand VDD and cholecalciferol's effects on the brain structure and function.

Causal effects of hypertensive disorders of pregnancy on structural changes in specific brain regions: a Mendelian randomization study

This study utilized Mendelian randomization to explore the impact of hypertensive disorders of pregnancy and their subtypes on brain structures, using genome-wide association study data from the FinnGen consortium for hypertensive disorders of pregnancy exposure and brain structure data from the ENIGMA consortium as outcomes. The inverse-variance weighted method, along with Cochran's Q test, Mendelian randomization-Egger regression, Mendelian randomization-PRESSO global test, and the leave-one-out approach, were applied to infer causality and assess heterogeneity and pleiotropy. Findings indicate hypertensive disorders of pregnancy are associated with structural brain alterations, including reduced cortical thickness in areas like the insula, isthmus cingulate gyrus, superior temporal gyrus, temporal pole, and transverse temporal gyrus, and an increased surface area in the superior frontal gyrus. Specific associations were found for hypertensive disorders of pregnancy subtypes: chronic hypertension with superimposed preeclampsia increased cortical thickness in the supramarginal gyrus; preeclampsia/eclampsia led to thinner cortex in the lingual gyrus and larger hippocampal volume and superior parietal lobule surface area. Chronic hypertension was associated with reduced cortical thickness in the caudal and rostral anterior cingulate and increased surface area of the cuneus and thickness of the pars orbitalis cortex. Gestational hypertension showed no significant brain region changes. These insights clarify hypertensive disorders of pregnancies' neurological and cognitive effects by identifying affected brain regions.

Coffee, antioxidants, and brain inflammation

Coffee is the most popular beverage in the world and, aside from tea and water, the most often consumed caffeine-containing beverage. Because of its high caffeine concentration, it is typically classified as a stimulant. There are other bioactive ingredients in coffee besides caffeine. The coffee beverage is a blend of several bioactive substances, including diterpenes (cafestol and kahweol), alkaloids (caffeine and trigonelline), and polyphenols (particularly chlorogenic acids in green beans and caffeic acid in roasted coffee beans). Caffeine has also been linked to additional beneficial benefits such as antioxidant and anti-inflammatory properties, which change cellular redox and inflammatory status in a dose-dependent manner. Pyrocatechol, a constituent of roasted coffee that is created when chlorogenic acid is thermally broken down, has anti-inflammatory properties as well. It is postulated that coffee consumption reduces neuroinflammation, which is intimately linked to the onset of neurodegenerative disorders like Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD). This review provides an overview of the most recent studies regarding coffee's possible benefits in preventing brain inflammation and neurodegenerative disorders.

Growth-Associated Protein 43 and Tensor-Based Morphometry Indices in Mild Cognitive Impairment

Growth-associated protein 43 (GAP-43) is found in the axonal terminal of neurons in the limbic system, which is affected in people with Alzheimer's disease (AD). We assumed GAP-43 may contribute to AD progression and serve as a biomarker. So, in a two-year follow-up study, we assessed GAP-43 changes and whether they are correlated with tensor-based morphometry (TBM) findings in patients with mild cognitive impairment (MCI). We included MCI and cognitively normal (CN) people with available baseline and follow-up cerebrospinal fluid (CSF) GAP-43 and TBM findings from the ADNI database. We assessed the difference between the two groups and correlations in each group at each time point. CSF GAP-43 and TBM measures were similar in the two study groups in all time points, except for the accelerated anatomical region of interest (ROI) of CN subjects that were significantly greater than those of MCI. The only significant correlations with GAP-43 observed were those inverse correlations with accelerated and non-accelerated anatomical ROI in MCI subjects at baseline. Plus, all TBM metrics decreased significantly in all study groups during the follow-up in contrast to CSF GAP-43 levels. Our study revealed significant associations between CSF GAP-43 levels and TBM indices among people of the AD spectrum.

Graph methods to infer spatial disturbances: Application to Huntington's Disease's speech

OBJECTIVE

Huntington's Disease (HD) is an inherited neurodegenerative disease caused by the mutation of the Htt gene, impacting all aspects of living and functioning. Among cognitive disabilities, spatial capacities are impaired, but their monitoring remains scarce as limited by lengthy experts' assessments. Language offers an alternative medium to evaluate patients' performance in HD. Yet, its capacities to assess HD's spatial abilities are unknown. Here, we aimed to bring proof-of-concept that HD's spatial deficits can be assessed through speech.

METHODS

We developed the Spatial Description Model to graphically represent spatial relations described during the Cookie Theft Picture (CTP) task. We increased the sensitivity of our model by using only sentences with spatial terms, unlike previous studies in Alzheimer's disease. 78 carriers of the mutant Htt, including 56 manifest and 22 premanifest individuals, as well as 25 healthy controls were included from the BIOHD & (NCT01412125) & Repair-HD (NCT03119246) cohorts. The convergence and divergence of the model were validated using the SelfCog battery.

RESULTS

Our Spatial Description Model was the only one among the four assessed approaches, revealing that individuals with manifest HD expressed fewer spatial relations and engaged in less spatial exploration compared to healthy controls. Their graphs correlated with both visuospatial and language SelfCog performances, but not with motor, executive nor memory functions.

CONCLUSIONS

We provide the proof-of-concept using our Spatial Description Model that language can grasp HD patient's spatial disturbances. By adding spatial capabilities to the panel of functions tested by the language, it paves the way for eventual remote clinical application.

Development of nanomedicines for the treatment of Alzheimer's disease: Raison d'être, strategies, challenges and regulatory aspects

Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by progressive loss of memory. Presently, AD is challenging to treat with current drug therapy as their delivery to the brain is restricted by the presence of the blood-brain barrier. Nanomedicines, due to their size, high surface volume ratio, and ease of tailoring drug release characteristics, showed their potential to treat AD. The nanotechnology-based formulations for brain targeting are expected to enter the market in the near future. So, regulatory frameworks are required to ensure the quality, safety, and effectiveness of the nanomedicines to treat AD. In this review, we discuss different strategies, in-vitro blood-brain permeation models, in-vivo permeation assessment, and regulatory aspects for the development of nanomedicine to treat AD.

Regional-based static and dynamic alterations in Alzheimer disease: a longitudinal study

BACKGROUND

 Alzheimer disease (AD) leads to cognitive decline and alters functional connectivity (FC) in key brain regions. Resting-state functional magnetic resonance imaging (rs-fMRI) assesses these changes using static-FC for overall correlation and dynamic-FC for temporal variability.

OBJECTIVE

 In AD, there is altered FC compared to normal conditions. The present study investigates possible region-specific functional abnormalities occurring longitudinally over 1 year. Our aim is to evaluate the potential usefulness of the static and dynamic approaches in identifying biomarkers of AD progression.

METHODS

 The study involved 15 AD and 20 healthy participants from the Alzheimer's Disease Neuroimaging Initiative 2 (ADNI2) database, tracked over 2 visits within 1 year. Using constrained-independent component analysis, we assessed FC changes across 80-regions of interest in AD over the year, examining both static and dynamic conditions.

RESULTS

 The average regional FC decreased in AD compared to healthy subjects at baseline and after 1 year. The dynamic condition identifies similarities with a few additional changes in the FC compared to the static condition. In both analyses, the baseline assessment revealed reduced connectivity between the following regions: right-middle-occipital and left-superior-occipital, left-hippocampus and right-postcentral, left-lingual and left-fusiform, and precuneus and left-thalamus. Additionally, increased connectivity was found between the left-superior-occipital and precuneus regions. In the 1-year AD assessment, increased connectivity was noted between the right-superior-temporal-pole and right-insular, right-hippocampus and left-caudate, right-middle-occipital and right-superior-temporal-pole, and posterior-cingulate-cortex and middle-temporal-pole regions.

CONCLUSION

 Significant changes were observed at baseline in the frontal, occipital, and core basal-ganglia regions, progressing towards the temporal lobe and subcortical regions in the following year. After 1 year, we observed the aforementioned region-specific neurological differences in AD, significantly aiding diagnosis and disease tracking.

Effect of Young Plasma Therapy on Cognition, Oxidative Stress, miRNA-134, BDNF, CREB, and SIRT-1 Expressions and Neuronal Survey in the Hippocampus of Aged Ovariectomized Rats with Alzheimer's

Menopause may increase the risk of Alzheimer's disease (AD) dementia. This study aimed to use young plasma therapy (YPT) to improve dementia caused by AD in aged ovariectomized rats. Female Wistar rats were used in the following groups: (a) young (CY) (180-200 g, 2-3 months, n = 10) and (b) old groups (250-350 g, 22-24 months, n = 60). The old rats were randomly assigned to six sub-groups: (1) control, (2) sham, (3) ovariectomized group (OVX), (4) OVX + Alzheimer disease (OVX + AD), (5) OVX + AD+ 17β-Estradiol (OVX + AD + E), and (6) OVX + AD + young plasma (OVX + AD + YP). Cognitive behaviors were evaluated using NOR, MWM, and PAL tests. MiR-134a, SIRT-1, CREB, and BDNF expressions were measured using real-time PCR and western blot, respectively. Oxidative stress in hippocampal tissue was assayed using ELISA kits. OVX and AD caused significant cognitive impairment (p < 0.001), up-regulated miR-134a (p < 0.001), down-regulated SIRT-1, CREB, and BDNF protein expression (p < 0.001), and decreased antioxidant marker levels (p < 0.001) compared to the sham group. YPT significantly restored miR-134a (p < 0.001), SIRT-1 (p < 0.001), CREB (p < 0.001), and BDNF (p < 0.001) protein expression in OVX + AD rats. YPT, as much as or more than estrogen therapy (ERT), significantly improved oxidative stress and down-regulated miR-134a expression and the up-regulation of SIRT-1, CREB, and BDNF proteins in OVX + AD rats (p < 0.001). YPT significantly improved histological alteration compared to the OVX + AD group (p < 0.001). As a non-pharmacological treatment, YPT can improve the expression of miR-134a and SIRT-1, CREB, and BDNF proteins as much as or more than estrogen therapy, ameliorating AD-induced dementia in aged OVX rats.

Traumatic brain injury alters the effects of class II invariant peptide (CLIP) antagonism on chronic meningeal CLIP + B cells, neuropathology, and neurobehavioral impairment in 5xFAD mice

BACKGROUND

Traumatic brain injury (TBI) is a significant risk factor for Alzheimer's disease (AD), and accumulating evidence supports a role for adaptive immune B and T cells in both TBI and AD pathogenesis. We previously identified B cell and major histocompatibility complex class II (MHCII)-associated invariant chain peptide (CLIP)-positive B cell expansion after TBI. We also showed that antagonizing CLIP binding to the antigen presenting groove of MHCII after TBI acutely reduced CLIP + splenic B cells and was neuroprotective. The current study investigated the chronic effects of antagonizing CLIP in the 5xFAD Alzheimer's mouse model, with and without TBI.

METHODS

12-week-old male wild type (WT) and 5xFAD mice were administered either CLIP antagonist peptide (CAP) or vehicle, once at 30 min after either sham or a lateral fluid percussion injury (FPI). Analyses included flow cytometric analysis of immune cells in dural meninges and spleen, histopathological analysis of the brain, magnetic resonance diffusion tensor imaging, cerebrovascular analysis, and assessment of motor and neurobehavioral function over the ensuing 6 months.

RESULTS

9-month-old 5xFAD mice had significantly more CLIP + B cells in the meninges compared to age-matched WT mice. A one-time treatment with CAP significantly reduced this population in 5xFAD mice. Importantly, CAP also improved some of the immune, histopathological, and neurobehavioral impairments in 5xFAD mice over the ensuing six months. Although FPI did not further elevate meningeal CLIP + B cells, it did negate the ability of CAP to reduce meningeal CLIP + B cells in the 5xFAD mice. FPI at 3 months of age exacerbated some aspects of AD pathology in 5xFAD mice, including further reducing hippocampal neurogenesis, increasing plaque deposition in CA3, altering microgliosis, and disrupting the cerebrovascular structure. CAP treatment after injury ameliorated some but not all of these FPI effects.

Protective effect of flavonoids on oxidative stress injury in Alzheimer's disease

Alzheimer's disease (AD) is the most common neurodegenerative disease, which is mainly caused by the damage of the structure and function of the central nervous system. At present, there are many adverse reactions in market-available drugs, which can't significantly inhibit the occurrence of AD. Therefore, the current focus of research is to find safe and effective therapeutic drugs to improve the clinical treatment of AD. Oxidative stress bridges different mechanism hypotheses of AD and plays a key role in AD. Numerous studies have shown that natural flavonoids have good antioxidant effects. They can directly or indirectly resist -oxidative stress, inhibit Aβ aggregation and Tau protein hyperphosphorylation by activating Nrf2 and other oxidation-antioxidation-related signals, regulating synaptic function-related pathways, promoting mitochondrial autophagy, etc., and play a neuroprotective role in AD. In this review, we summarised the mechanism of flavonoids inhibiting oxidative stress injury in AD in recent years. Moreover, because of the shortcomings of poor biofilm permeability and low bioavailability of flavonoids, the advantages and recent research progress of nano-drug delivery systems such as liposomes and solid lipid nanoparticles were highlighted. We hope this review provides a useful way to explore safe and effective AD treatments.

Laser-activated perfluorocarbon nanodroplets for intracerebral delivery and imaging via blood-brain barrier opening and contrast-enhanced imaging

BACKGROUND

Ultrasound and photoacoustic (US/PA) imaging is a promising tool for in vivo visualization and assessment of drug delivery. However, the acoustic properties of the skull limit the practical application of US/PA imaging in the brain. To address the challenges in targeted drug delivery to the brain and transcranial US/PA imaging, we introduce and evaluate an intracerebral delivery and imaging strategy based on the use of laser-activated perfluorocarbon nanodroplets (PFCnDs).

METHODS

Two specialized PFCnDs were developed to facilitate blood‒brain barrier (BBB) opening and contrast-enhanced US/PA imaging. In mice, PFCnDs were delivered to brain tissue via PFCnD-induced BBB opening to the right side of the brain. In vivo, transcranial US/PA imaging was performed to evaluate the utility of PFCnDs for contrast-enhanced imaging through the skull. Ex vivo, volumetric US/PA imaging was used to characterize the spatial distribution of PFCnDs that entered brain tissue. Immunohistochemical analysis was performed to confirm the spatial extent of BBB opening and the accuracy of the imaging results.

RESULTS

In vivo, transcranial US/PA imaging revealed localized photoacoustic (PA) contrast associated with delivered PFCnDs. In addition, contrast-enhanced ultrasound (CEUS) imaging confirmed the presence of nanodroplets within the same area. Ex vivo, volumetric US/PA imaging revealed PA contrast localized to the area of the brain where PFCnD-induced BBB opening had been performed. Immunohistochemical analysis revealed that the spatial distribution of immunoglobulin (IgG) extravasation into the brain closely matched the imaging results.

CONCLUSIONS

Using our intracerebral delivery and imaging strategy, PFCnDs were successfully delivered to a targeted area of the brain, and they enabled contrast-enhanced US/PA imaging through the skull. Ex vivo imaging, and immunohistochemistry confirmed the accuracy and precision of the approach.

Altered Hierarchical Gradients of Intrinsic Neural Timescales in Mild Cognitive Impairment and Alzheimer's Disease

Alzheimer's disease (AD) is a devastating neurodegenerative disease that affects millions of seniors in the United States. Resting-state functional magnetic resonance imaging (rs-fMRI) is widely used to study neurophysiology in AD and its prodromal condition, mild cognitive impairment (MCI). The intrinsic neural timescale (INT), which can be estimated through the magnitude of the autocorrelation of neural signals from rs-fMRI, is thought to quantify the duration that neural information is stored in a local circuit. Such heterogeneity of the timescales forms a basis of the brain functional hierarchy and captures an aspect of circuit dynamics relevant to excitation/inhibition balance, which is broadly relevant for cognitive functions. Given that, we applied rs-fMRI to test whether distinct changes of INT at different hierarchies are present in people with MCI, those progressing to AD (called Converter), and AD patients of both sexes. Linear mixed-effect model was implemented to detect altered hierarchical gradients across populations followed by pairwise comparisons to identify regional differences. High similarities between AD and Converter were observed. Specifically, the inferior temporal, caudate, and pallidum areas exhibit significant alterations in both AD and Converter. Distinct INT-related pathological changes in MCI and AD were found. For AD/Converter, neural information is stored for a longer time in lower hierarchical areas, while higher levels of hierarchy seem to be preferentially impaired in MCI leading to a less pronounced hierarchical gradient. These results inform that the INT holds great potential as an additional measure for AD prediction, even a stable biomarker for clinical diagnosis.

Predicting conversion from mild cognitive impairment to Alzheimer's disease: a multimodal approach

Successively predicting whether mild cognitive impairment patients will progress to Alzheimer's disease is of significant clinical relevance. This ability may provide information that can be leveraged by emerging intervention approaches and thus mitigate some of the negative effects of the disease. Neuroimaging biomarkers have gained some attention in recent years and may be useful in predicting the conversion of mild cognitive impairment to Alzheimer's disease. We implemented a novel multi-modal approach that allowed us to evaluate the potential of different imaging modalities, both alone and in different degrees of combinations, in predicting the conversion to Alzheimer's disease of mild cognitive impairment patients. We applied this approach to the imaging data from the Alzheimer's Disease Neuroimaging Initiative that is a multi-modal imaging dataset comprised of MRI, Fluorodeoxyglucose PET, Florbetapir PET and diffusion tensor imaging. We included a total of 480 mild cognitive impairment patients that were split into two groups: converted and stable. Imaging data were segmented into atlas-based regions of interest, from which relevant features were extracted for the different imaging modalities and used to construct machine-learning models to classify mild cognitive impairment patients into converted or stable, using each of the different imaging modalities independently. The models were then combined, using a simple weight fusion ensemble strategy, to evaluate the complementarity of different imaging modalities and their contribution to the prediction accuracy of the models. The single-modality findings revealed that the model, utilizing features extracted from Florbetapir PET, demonstrated the highest performance with a balanced accuracy of 83.51%. Concerning multi-modality models, not all combinations enhanced mild cognitive impairment conversion prediction. Notably, the combination of MRI with Fluorodeoxyglucose PET emerged as the most promising, exhibiting an overall improvement in predictive capabilities, achieving a balanced accuracy of 78.43%. This indicates synergy and complementarity between the two imaging modalities in predicting mild cognitive impairment conversion. These findings suggest that β-amyloid accumulation provides robust predictive capabilities, while the combination of multiple imaging modalities has the potential to surpass certain single-modality approaches. Exploring modality-specific biomarkers, we identified the brainstem as a sensitive biomarker for both MRI and Fluorodeoxyglucose PET modalities, implicating its involvement in early Alzheimer's pathology. Notably, the corpus callosum and adjacent cortical regions emerged as potential biomarkers, warranting further study into their role in the early stages of Alzheimer's disease.

Hippocampal transcriptome-wide association study and pathway analysis of mitochondrial solute carriers in Alzheimer's disease

The etiopathogenesis of late-onset Alzheimer's disease (AD) is increasingly recognized as the result of the combination of the aging process, toxic proteins, brain dysmetabolism, and genetic risks. Although the role of mitochondrial dysfunction in the pathogenesis of AD has been well-appreciated, the interaction between mitochondrial function and genetic variability in promoting dementia is still poorly understood. In this study, by tissue-specific transcriptome-wide association study (TWAS) and further meta-analysis, we examined the genetic association between mitochondrial solute carrier family (SLC25) genes and AD in three independent cohorts and identified three AD-susceptibility genes, including SLC25A10, SLC25A17, and SLC25A22. Integrative analysis using neuroimaging data and hippocampal TWAS-predicted gene expression of the three susceptibility genes showed an inverse correlation of SLC25A22 with hippocampal atrophy rate in AD patients, which outweighed the impacts of sex, age, and apolipoprotein E4 (ApoE4). Furthermore, SLC25A22 downregulation demonstrated an association with AD onset, as compared with the other two transcriptome-wide significant genes. Pathway and network analysis related hippocampal SLC25A22 downregulation to defects in neuronal function and development, echoing the enrichment of SLC25A22 expression in human glutamatergic neurons. The most parsimonious interpretation of the results is that we have identified AD-susceptibility genes in the SLC25 family through the prediction of hippocampal gene expression. Moreover, our findings mechanistically yield insight into the mitochondrial cascade hypothesis of AD and pave the way for the future development of diagnostic tools for the early prevention of AD from a perspective of precision medicine by targeting the mitochondria-related genes.

Potential prognostic value of CSF-targeted proteomics across the Alzheimer's disease continuum

BACKGROUND

Core biomarkers for Alzheimer's disease (AD), such as Aβ42 and tau, have demonstrated high prognostic accuracy but do not fully capture the complex pathophysiology of AD. In this study, our objective was to identify novel cerebrospinal fluid (CSF) biomarkers using proteomics across the entire AD continuum to predict conversion to AD and explore their involvement in AD pathogenesis.

METHODS

A cohort of 186 cognitively normal (CN), 127 subjective memory complaint (SMC), 79 early mild cognitive impairment (EMCI), 249 late MCI (LMCI), and 132 AD individuals was analyzed, with a follow-up period of over 3 years for non-AD participants. CSF 65 peptides, as well as hippocampal and entorhinal volumes were analyzed, and cognitive function was evaluated using the 13-item cognitive subscale of the Alzheimer's Disease Assessment Scale (ADAS-Cog 13). Cox proportional hazards models and mediation analysis were performed to investigate associations and causal relationships.

RESULTS

During the follow-up, approximately one-fourth (146/580) of the non-AD participants progressed to AD. After adjusting for baseline diagnosis (CN to LMCI) and other variables, multivariable Cox regression analysis identified three peptides (VAELEDEK, VSFELFADK, and VVSSIEQK) as significant predictors of conversion to AD. Incorporating these three peptides into the initial model significantly improved the C-statistic from 0.82 to 0.85 for predicting AD conversion, surpassing the predictive ability of Aβ42 and P-tau. Moreover, hippocampal and entorhinal volumes mediated 30.3-53.8% of the association between the three peptides and ADAS-Cog 13 scores.

CONCLUSIONS

These findings underscore the potential of these three peptides as robust prognostic biomarker candidates for AD conversion across the entire AD continuum, with a mechanism involving the mediation of hippocampal and entorhinal volumes.

Oligomeric amyloid-β targeted contrast agent for MRI evaluation of Alzheimer's disease mouse models

Background

Oligomeric amyloid beta (oAβ) is a toxic factor that acts in the early stage of Alzheimer's disease (AD) and may initiate the pathologic cascade. Therefore, detecting oAβ has a crucial role in the early diagnosis, monitoring, and treatment of AD.

Purpose

The purpose of this study was to evaluate MRI signal changes in different mouse models and the time-dependent signal changes using our novel gadolinium (Gd)-dodecane tetraacetic acid (DOTA)- ob5 aptamer contrast agent.

Methods

We developed an MRI contrast agent by conjugating Gd-DOTA-DNA aptamer called ob5 to evaluate its ability to detect oAβ deposits in the brain using MRI. A total of 10 control mice, 9 3xTg AD mice, and 11 APP/PS/Tau AD mice were included in this study, with the age of each model being 16 or 36 weeks. A T1-weighted image was acquired at the time points before (0 min) and after injection of the contrast agent at 5, 10, 15, 20, and 25 min. The analyses were performed to compare MRI signal differences among the three groups and the time-dependent signal differences in different mouse models.

Results

Both 3xTg AD and APP/PS/Tau AD mouse models had higher signal enhancement than control mice at all scan-time points after injection of our contrast media, especially in bilateral hippocampal areas. In particular, all Tg AD mouse models aged 16 weeks showed a higher contrast enhancement than those aged 36 weeks. For 3xTg AD and APP/PS/Tau AD groups, the signal enhancement was significantly different among the five time points (0 min, 5 min, 10 min, 15 min, 20 min, and 25 min) in multiple ROI areas, typically in the bilateral hippocampus, left thalamus, and left amygdala.

Conclusion

The findings of this study suggest that the expression of the contrast agent in different AD models demonstrates its translational flexibility across different species. The signal enhancement peaked around 15-20 min after injection of the contrast agent. Therefore, our novel contrast agent targeting oAβ has the potential ability to diagnose early AD and monitor the progression of AD.

Bayesian genome-wide TWAS with reference transcriptomic data of brain and blood tissues identified 141 risk genes for Alzheimer's disease dementia

BACKGROUND

Transcriptome-wide association study (TWAS) is an influential tool for identifying genes associated with complex diseases whose genetic effects are likely mediated through transcriptome. TWAS utilizes reference genetic and transcriptomic data to estimate effect sizes of genetic variants on gene expression (i.e., effect sizes of a broad sense of expression quantitative trait loci, eQTL). These estimated effect sizes are employed as variant weights in gene-based association tests, facilitating the mapping of risk genes with genome-wide association study (GWAS) data. However, most existing TWAS of Alzheimer's disease (AD) dementia are limited to studying only cis-eQTL proximal to the test gene. To overcome this limitation, we applied the Bayesian Genome-wide TWAS (BGW-TWAS) method to leveraging both cis- and trans- eQTL of brain and blood tissues, in order to enhance mapping risk genes for AD dementia.

METHODS

We first applied BGW-TWAS to the Genotype-Tissue Expression (GTEx) V8 dataset to estimate cis- and trans- eQTL effect sizes of the prefrontal cortex, cortex, and whole blood tissues. Estimated eQTL effect sizes were integrated with the summary data of the most recent GWAS of AD dementia to obtain BGW-TWAS (i.e., gene-based association test) p-values of AD dementia per gene per tissue type. Then we used the aggregated Cauchy association test to combine TWAS p-values across three tissues to obtain omnibus TWAS p-values per gene.

RESULTS

We identified 85 significant genes in prefrontal cortex, 82 in cortex, and 76 in whole blood that were significantly associated with AD dementia. By combining BGW-TWAS p-values across these three tissues, we obtained 141 significant risk genes including 34 genes primarily due to trans-eQTL and 35 mapped risk genes in GWAS Catalog. With these 141 significant risk genes, we detected functional clusters comprised of both known mapped GWAS risk genes of AD in GWAS Catalog and our identified TWAS risk genes by protein-protein interaction network analysis, as well as several enriched phenotypes related to AD.

CONCLUSION

We applied BGW-TWAS and aggregated Cauchy test methods to integrate both cis- and trans- eQTL data of brain and blood tissues with GWAS summary data, identifying 141 TWAS risk genes of AD dementia. These identified risk genes provide novel insights into the underlying biological mechanisms of AD dementia and potential gene targets for therapeutics development.

Molecular mechanisms implicated in protein changes in the Alzheimer's disease human hippocampus

This study aimed to elucidate the specific biochemical pathways linked to changes in proteins in the Alzheimer's disease (AD) human hippocampus. Our data demonstrate a constant rise in the expression of four proteins (VGF, GFAP, HSPB1, and APP) across all eleven studies. Notably, UBC was the most centrally involved and had increased expression in the hippocampus tissue of individuals with AD. Modified proteins in the hippocampal tissue were found to activate the innate immune system and disrupt communication across chemical synapses. Four hub proteins (CD44, APP, ITGB2, and APOE) are connected to amyloid plaques, whereas two hub proteins (RPL24 and RPS23) are related to neurofibrillary tangles (NFTs). The presence of modified proteins was discovered to trigger the activation of microglia and decrease the functioning of ribosomes and mitochondria in the hippocampus. Three significant microRNAs (hsa-miR-106b-5p, hsa-miR-17-5p, and hsa-miR-16-5p) and transcription factors (MYT1L, PIN1, and CSRNP3) have been discovered to improve our understanding of the alterations in proteins within the hippocampal tissues that lead to the progression of AD. These findings establish a path for possible treatments for AD to employ therapeutic strategies that specifically focus on the proteins or processes linked to the illness.

Long-lasting increases in GABAB receptor subunit levels in hippocampal dentate gyrus of mice with a single systemic injection of trimethyltin

We have recently shown delayed increases in GABAB receptor (GABABR) subunit protein levels in the hippocampal dentate gyrus (DG), but not in the pyramidal CA1 and CA3 regions, at 15-30 days after the systemic single administration of trimethyltin (TMT) in mice. An attempt was thus made to determine whether the delayed increases return to the control levels found in naive mice afterward. In the DG on hippocampal slices obtained at 90 days after the administration, however, marked increases were still seen in protein levels of both GABABR1 and GABABR2 subunits without significant changes in calbindin and glial fibrillary acidic protein (GFAP) levels on immunoblotting analysis. Fluoro-Jade B staining clearly revealed the absence of degenerated neurons from the DG at 90 days after the administration. Although co-localization was invariably detected between GABABR2 subunit and GFAP in the DG at 30 days on immunohistochemical analysis, GABABR2-positive cells did not merge well with GFAP-positive cells in the DG at 90 days. These results suggest that both GABABR1 and GABABR2 subunits would be tardily and sustainably up-regulated by cells other than neurons and astrocytes in the murine DG at 90 days after a systemic single injection of TMT.

Protein Oxidation in Aging and Alzheimer's Disease Brain

Proteins are essential molecules that play crucial roles in maintaining cellular homeostasis and carrying out biological functions such as catalyzing biochemical reactions, structural proteins, immune response, etc. However, proteins also are highly susceptible to damage by reactive oxygen species (ROS) and reactive nitrogen species (RNS). In this review, we summarize the role of protein oxidation in normal aging and Alzheimer's disease (AD). The major emphasis of this review article is on the carbonylation and nitration of proteins in AD and mild cognitive impairment (MCI). The oxidatively modified proteins showed a strong correlation with the reported changes in brain structure, carbohydrate metabolism, synaptic transmission, cellular energetics, etc., of both MCI and AD brains compared to the controls. Some proteins were found to be common targets of oxidation and were observed during the early stages of AD, suggesting that those changes might be critical in the onset of symptoms and/or formation of the pathological hallmarks of AD. Further studies are required to fully elucidate the role of protein oxidation and nitration in the progression and pathogenesis of AD.