Alzheimer's Disease Hippocampus Research Articles

Transcriptomic analysis reveals sex-specific patterns in the hippocampus in Alzheimer's disease.

The hippocampus, vital for memory and learning, is among the first brain regions affected in Alzheimer's Disease (AD) and exhibits adult neurogenesis. Women face twice the risk of developing AD compare to men, making it crucial to understand sex differences in hippocampal function for comprehending AD susceptibility. We conducted a comprehensive analysis of bulk mRNA postmortem samples from the whole hippocampus (GSE48350, GSE5281) and its CA1 and CA3 subfields (GSE29378). Our aim was to perform a comparative molecular signatures analysis, investigating sex-specific differences and similarities in the hippocampus and its subfields in AD. This involved comparing the gene expression profiles among: (a) male controls (M-controls) vs. female controls (F-controls), (b) females with AD (F-AD) vs. F-controls, (c) males with AD (M-AD) vs. M-controls, and (d) M-AD vs. F-AD. Furthermore, we identified AD susceptibility genes interacting with key targets of menopause hormone replacement drugs, specifically the ESR1 and ESR2 genes, along with GPER1. The hippocampal analysis revealed contrasting patterns between M-AD vs. M-controls and F-AD vs. F-controls, as well as M-controls vs. F-controls. Notably, BACE1, a key enzyme linked to amyloid-beta production in AD pathology, was found to be upregulated in M-controls compared to F-controls in both CA1 and CA3 hippocampal subfields. In M-AD vs. M-controls, the GABAergic synapse was downregulated, and the Estrogen signaling pathway was upregulated in both subfields, unlike in F-AD vs. F-controls. Analysis of the whole hippocampus also revealed upregulation of the GABAergic synapse in F-AD vs. F-controls. While direct comparison of M-AD vs. F-AD, revealed a small upregulation of the ESR1 gene in the CA1 subfield of males. Conversely, F-AD vs. F-controls exhibited downregulation of the Dopaminergic synapse in both subfields, while the Calcium signaling pathway showed mixed regulation, being upregulated in CA1 but downregulated in CA3, unlike in M-AD vs. M-controls. The upregulated Estrogen signaling pathway in M-AD, suggests a compensatory response to neurodegenerative specifically in males with AD. Our results also identified potential susceptibility genes interacting with ESR1 and ESR2, including MAPK1, IGF1, AKT1, TP53 and CD44. These findings underscore the importance of sex-specific disease mechanisms in AD pathogenesis. Region-specific analysis offers a more detailed examination of localized changes in the hippocampus, enabling to capture sex-specific molecular patterns in AD susceptibility and progression.

Identification of IGF-1 Effects on White Adipose Tissue and Hippocampus in Alzheimer's Disease Mice via Transcriptomic and Cellular Analysis.

Alzheimer's disease (AD) stands as the most prevalent neurodegenerative disorder, characterized by a multitude of pathological manifestations, prominently marked by the aggregation of amyloid beta. Recent investigations have revealed a compelling association between excessive adiposity and glial activation, further correlating with cognitive impairments. Additionally, alterations in levels of insulin-like growth factor 1 (IGF-1) have been reported in individuals with metabolic conditions accompanied by memory dysfunction. Hence, our research endeavors to comprehensively explore the impact of IGF-1 on the hippocampus and adipose tissue in the context of Alzheimer's disease. To address this, we have conducted an in-depth analysis utilizing APP/PS2 transgenic mice, recognized as a well-established mouse model for Alzheimer's disease. Upon administering IGF-1 injections to the APP/PS2 mice, we observed notable alterations in their behavioral patterns, prompting us to undertake a comprehensive transcriptomic analysis of both the hippocampal and adipose tissues. Our data unveiled significant modifications in the functional profiles of these tissues. Specifically, in the hippocampus, we identified changes associated with synaptic activity and neuroinflammation. Concurrently, the adipose tissue displayed shifts in processes related to fat browning and cell death signaling. In addition to these findings, our analysis enabled the identification of a collection of long non-coding RNAs and circular RNAs that exhibited significant changes in expression subsequent to the administration of IGF-1 injections. Furthermore, we endeavored to predict the potential roles of these identified RNA molecules within the context of our study. In summary, our study offers valuable transcriptome data for hippocampal and adipose tissues within an Alzheimer's disease model and posits a significant role for IGF-1 within both the hippocampus and adipose tissue.

Tracing synaptic loss in Alzheimer's brain with SV2A PET-tracer UCB-J.

Synaptic loss is an early prominent feature of Alzheimer's disease (AD). The recently developed novel synaptic vesicle 2A protein (SV2A) PET-tracer UCB-J has shown great promise in tracking synaptic loss in AD. However, there have been discrepancies between the findings and a lack of mechanistic insight. Here we report the first extensive pre-clinical validation studies for UCB-J in control (CN; n=11) and AD (n=11) brains using a multidimensional approach of post-mortem brain imaging techniques, radioligand binding, and biochemical studies. We demonstrate that UCB-J could target SV2A protein with high specificity and depict synaptic loss at synaptosome levels in AD brain regions compared to CNs. UCB-J showed highest synaptic loss in AD hippocampus followed in descending order by frontal cortex, temporal cortex, parietal cortex, and cerebellum. 3H-UCB-J large brain-section autoradiography and cellular/subcellular fractions binding studies indicated potential off-target interaction with phosphorylated tau (p-tau) species in AD brains, which could have subsequent clinical implications for imaging studies. Synaptic positron emission tomography (PET)-tracer UCB-J could target synaptic vesicle 2A protein (SV2A) with high specificity in Alzheimer's disease (AD) and control brains. Synaptic PET-tracer UCB-J could depict synaptic loss at synaptosome levels in AD brain regions compared to control. Potential off-target interaction of UCB-J with phosphorylated tau (p-tau) species at cellular/subcellular levels could have subsequent clinical implications for imaging studies, warranting further investigations.

Antagonizing LINGO-1 reduces activated microglia and alleviates dendritic spine loss in the hippocampus of APP/PS1 transgenic mice

In Alzheimer's disease (AD), microglia are involved in synaptic pruning and mediate synapse loss. LINGO-1 is a negative regulator of nerve growth, and whether antagonizing LINGO-1 can attenuate synaptic pruning by microglia and rescue dendritic spines in the hippocampus in AD is still unclear. On this basis, the anti-LINGO-1 antibody, which binds to LINGO-1 protein and antagonizes the effects of LINGO-1, was administered to 10-month-old APP/PS1 transgenic mice for 2 months. The Morris water maze test, immunohistochemical and stereological methods, immunofluorescence and 3D reconstruction were used. Compared to wild-type mice, APP/PS1 transgenic mice had worse performance on behavioral tests, fewer dendritic spines but more microglia in the hippocampus. Meanwhile, the microglia in APP/PS1 transgenic mice had more branches of medium length (4–6 µm) and a cell body area with greater variability. Moreover, APP/PS1 transgenic mice had more postsynaptic termini colocalized with microglia in the hippocampus than wild-type mice. The anti-LINGO-1 antibody significantly reversed these changes in AD, indicating that the anti-LINGO-1 antibody can improve hippocampus-dependent learning and memory abilities and effectively rescue dendritic spines in the hippocampus of AD mice and that microglia might participate in this progression in AD. These results provide a scientific basis for further studying the mechanism of the anti-LINGO-1 antibody in AD and help to elucidate the role of LINGO-1 in the treatment of AD.

Different dysregulations of CYFIP1 and CYFIP2 in distinct types of dementia

In humans, the cytoplasmic FMR1 interacting protein (CYFIP) family consists of two members, namely CYFIP1 and CYFIP2. Both CYFIP1 and CYFIP2 function in the WAVE regulatory complex (WRC), which regulates actin polymerization. Additionally, these two proteins form a posttranscriptional regulatory complex with the fragile X mental retardation protein (FMRP), which suppresses mRNA translation. Thus, CYFIP1 and CYFIP2 are important signalling regulators at synapses, and mutations in their genes are associated with neurodevelopmental and neuropsychiatric disorders, including intellectual disabilities. Moreover, dysregulation of the CYFIP protein family is involved in Alzheimer’s disease (AD). However, the relevance of the CYFIP family in other dementias is largely unknown. Here, we compared CYFIP1/2 protein levels in the post-mortem hippocampus from patients with AD, dementia with Lewy bodies (DLB), vascular dementia (VaD) and frontotemporal lobar degeneration with TDP-43 pathology (FTLD-TDP). Consistent with previous findings, CYFIP2 was reduced in AD hippocampus. In DLB and VaD hippocampus, the protein level of CYFIP2 and CYFIP1 was unaltered. Finally, an increase in the protein level of both CYFIP1 and CYFIP2 was noted in FTLD-TDP hippocampus. These findings reveal that the protein levels of the CYFIP family is distinct in different types of dementia, suggesting that the pathogenesis of these neurodegenerative disorders has divergent impacts on hippocampal synaptic function.

Exploring the Potential of Radiomics Features of the Hippocampus in Alzheimer’s Disease Considering Standard versus Parallel Imaging

AbstractBackgroundRadiomics features obtained from anatomical magnetic resonance imaging (MRI) have been showing potential as biomarkers for the diagnosis of Alzheimer’s disease (AD). Nevertheless, little is known about how accelerated parallel MRI acquisitions impact such features and their potential in diagnosing AD. Therefore, this study aimed to compare the radiomics features extracted from the hippocampus considering standard and parallel imaging.MethodA total of 235 age and gender‐matched subjects (128 cognitively normal (CN) and 107 AD) with both T1‐weighted MPRAGE (standard) and accelerated MPRAGE GRAPPA or SENSE images were selected from the Alzheimer’s Disease Neuroimaging Initiative (ADNI). Freesurfer was used to process the images and to obtain the volumes of these regions: hippocampus, entorhinal cortex, amygdala, and inferior lateral ventricle (summed bilaterally); and caudal and rostral midfrontal, pars opercularis, pars triangularis, inferior parietal, superior parietal, supramarginal, and superior temporal gyri (all summed into one feature). Using Pyradiomics, the following radiomics features from the bilateral hippocampus were extracted: kurtosis, mean, range, contrast, elongation, flatness, and maximum 3D diameter. To compare the two acquisitions (standard vs parallel), support vector machine models were created to classify AD vs CN. To mitigate AD heterogeneity in ADNI, 5‐fold cross‐validation was used to create 5 train and test sets based on the hippocampus volumes: (each train fold has 80% of 1st quartile AD and 80% 1st quartile CN, and the test fold has 20% of 1st quartile AD and 20% 1st quartile CN volumes, and so on – randomly selected).ResultAdding radiomics features improved the classification of AD vs CN in both acquisitions (Table 1): the positive predictive value increased from 77.2% to 90.3% in the standard, while the negative predictive value increased to 84.7% to 91.6% in the parallel acquisition. In both cases, models using all volumes surpassed those using only the hippocampus volume by 7.4% (86.0% balanced accuracy, standard) and 4.2% (85.5%, balanced accuracy, parallel) (Table 1).ConclusionRadiomics features of the hippocampus improve the performance of the models in both acquisitions, but with different predictive values, confirming their potential. Also, the relevance of other brain regions in AD besides the hippocampus was observed.

Extracellular Tau Oligomers Damage the Axon Initial Segment by an Endogenous Tau‐Dependent Mechanism

AbstractBackgroundNeuronal polarity and synaptic connectivity are compromised in Alzheimer’s disease (AD) and other tauopathies. The axon initial segment (AIS) is a key structure for regulating polarity and functions of neurons. It occupies the first 20‐60 µm of the axon, comprises a diffusion barrier that segregates axon‐enriched from somatodendritic‐enriched molecules, and has a high concentration of voltage‐gated ion channels that generate action potentials. Extracellular amyloid‐β oligomers compromise AIS integrity. However, effects on the AIS of toxic tau species, including extracellular oligomers (xcTauOs) that spread tau pathology from neuron to neuron by a prion‐like process, whereas unknown. Therefore, we wanted to test the hypothesis that AIS structure is sensitive to xcTauOs.MethodPrimary cortical neurons derived from either wild type (WT), or tau knockout (KO) mice were exposed to xcTauOs or vehicle. Quantitative western blotting and immunofluorescence microscopy with an antibody against the AIS‐enriched protein TRIM46 was used to monitor effects on the AIS. The same methods were also used to compare TRIM46 and two other AIS proteins, ankyrin‐G and neurofascin‐186 in human hippocampal tissue obtained from AD and age‐matched non‐AD donors.ResultIn cultured WT, but not TKO neurons, xcTauOs cause a trend toward AIS shortening and reduce the concentration of the resident AIS protein, TRIM46, without affecting total TRIM46 levels. Lentiviral‐driven human tau expression in tau KO neurons rescues TRIM46 sensitivity to xcTauOs. In human AD hippocampus, AIS length and TRIM46 concentration within the AIS are reduced in neurons containing neurofibrillary tangles (NFTs), without affecting the overall protein levels of multiple resident AIS proteins.ConclusionThese collective findings demonstrate that in cultured neurons, xcTauOs cause partial AIS damage by a mechanism dependent on intracellular tau, thereby raising the possibility that AIS reduction in AD is caused by xcTauOs working in concert with endogenous neuronal tau.

Gardenia jasminoides J. Ellis extract attenuates memory impairment in rats with Alzheimer’s disease by suppressing NLRP3 inflammasome

Alzheimer’s disease (AD) is characterized by degeneration of the central nervous system. Recently, many studies have emphasized the beneficial role of Gardenia jasminoides J. Ellis extract (GJ-4) in neuroprotection, which is considered a potential drug for treating AD. However, the mechanism underlying its neuroprotective effects is obscure. This research intended to analyze the effectiveness of GJ-4 to induce neuronal protective role on a rat model of neurotoxicity and probe the potential mechanism. An AD model was established by intraperitoneal injection of aluminum chloride (AlCl3). Then, AlCl3-induced rats were administered 25 mg/kg and 50 mg/kg of GJ-4 orally. This study indicated that GJ-4 (25 and 50 mg/kg) mitigated AD-like behaviors, as evidenced by enhanced ambulation frequency, rearing frequency, and time spent in the target quadrant and decreased grooming frequency, defecation frequency, and escape latency in AlCl3-challenged rats. Also, GJ-4 at 25 and 50 mg/kg exerted an anti-apoptosis effect in the hippocampus of AlCl3-treated rats. Furthermore, GJ-4 (25 and 50 mg/kg) exhibited an anti-inflammatory effect in the hippocampus by repressing the activation of NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome, further inhibiting the activation of Caspase 1, ASC, IL-1β, and IL-18 in AD hippocampus. Altogether, GJ-4 mitigated AlCl3-triggered impairment of learning and memory in AD rats via repressing NLRP3 inflammasome.

Liquid Biopsy in Alzheimer's Disease Patients Reveals Epigenetic Changes in the PRLHR Gene.

In recent years, new DNA methylation variants have been reported in genes biologically relevant to Alzheimer's disease (AD) in human brain tissue. However, this AD-specific epigenetic information remains brain-locked and unreachable during patients' lifetimes. In a previous methylome performed in the hippocampus of 26 AD patients and 12 controls, we found higher methylation levels in AD patients in the promoter region of PRLHR, a gene involved in energy balance regulation. Our aim was to further characterize PRLHR's role in AD and to evaluate if the liquid biopsy technique would provide life access to this brain information in a non-invasive way. First, we extended the methylation mapping of PRLHR and validated previous methylome results via bisulfite cloning sequencing. Next, we observed a positive correlation between PRLHR methylation levels and AD-related neuropathological changes and a decreased expression of PRLHR in AD hippocampus. Then, we managed to replicate the hippocampal methylation differences in plasma cfDNA from an additional cohort of 35 AD patients and 35 controls. The isolation of cfDNA from the plasma of AD patients may constitute a source of potential epigenetic biomarkers to aid AD clinical management.

Changes of tRNA-Derived Fragments by Alzheimer's Disease in Cerebrospinal Fluid and Blood Serum.

Alzheimer's disease (AD) is the most common type of dementia, affecting individuals over 65. AD is also a multifactorial disease, with disease mechanisms incompletely characterized, and disease-modifying therapies are marginally effective. Biomarker signatures may shed light on the diagnosis, disease mechanisms, and the development of therapeutic targets. tRNA-derived RNA fragments (tRFs), a family of recently discovered small non-coding RNAs, have been found to be significantly enhanced in human AD hippocampus tissues. However, whether tRFs change in body fluids is unknown. To investigate whether tRFs in body fluids are impacted by AD. We first used T4 polynucleotide kinase-RNA-seq, a modified next-generation sequencing technique, to identify detectable tRFs in human cerebrospinal fluid and serum samples. The detectable tRFs were then compared in these fluids from control, AD, and mild cognitive impairment patients using tRF qRT-PCR. The stability of tRFs in serum was also investigated by checking the change in tRFs in response to protein digestion or exosome lysis. Among various tRFs, tRF5-ProAGG seemed to be impacted by AD in both cerebrospinal fluid and serum. AD-impacted serum tRF5-ProAGG showed a correlation with the AD stage. Putative targets of tRF5-ProAGG in the hippocampus were also predicted by a computational algorithm, with some targets being validated experimentally and one of them being in a negative correlation with tRF5-ProAGG even using a small size of samples. tRF5-ProAGG showed the potential as an AD biomarker and may play a role in disease progression.

Sex difference in brain functional connectivity of hippocampus in Alzheimer's disease.

Alzheimer's disease (AD), affecting nearly 6.5 million people, is the fifth leading cause of death in individuals 65years or older in the USA. Prior research has shown that AD disproportionality affects females; females have a greater incidence rate, perform worse on a variety of neuropsychological tasks, and have greater total brain atrophy. Recent research has linked these sex differences to neuroimaging markers of brain pathology, such as hippocampal volumes. Specifically, research from our lab found that functional connectivity from the hippocampus to the precuneus cortex and brain stem was significantly stronger in males than in females with mild cognitive impairment. The aim of this study was to extend our understanding to individuals with AD and to determine if these potential sex-specific functional connectivity biomarkers extend through different disease stages. The resting state fMRI and T2 MRI of cognitively normal individuals (n = 32, female = 16) and individuals with AD (n = 32, female = 16) from the Alzheimer's Disease Neuroimaging Initiative (ADNI) were analyzed using the Functional Connectivity Toolbox (CONN). Our results demonstrate that males had a significantly stronger interhemispheric functional connectivity between the left and right hippocampus compared to females. These results improve our current understanding of the role of the hippocampus in sex differences in AD. Understanding the contribution of impaired functional connectivity sex differences may aid in the development of sex-specific precision medicine for improved AD treatment.

The bidirectional relationship between Alzheimer's disease (AD) and epilepsy: A Mendelian randomization study.

There is a complex, bidirectional relationship between Alzheimer's disease (AD) and epilepsy. However, the causality of this association is unclear, as confounders play a role in this association. We conducted a Mendelian randomization (MR) study to clarify the causal relationship and direction of epilepsy on AD risk. We used publicly available summary statistics to obtain all genetic datasets for the MR analyses. AD and AD-by-proxy and late-onset AD (LOAD) cohorts were included in our study. The epilepsy cohort comprised all epilepsy, generalized epilepsy, focal epilepsy, and its subtypes, as well as some epilepsy syndromes. Next, we conducted validation using another AD cohort. Two correlations between AD and epilepsy using the inverse variance-weighted (IVW) method are as follows: LOAD and focal epilepsy (ORIVW =1.079, pIVW =.013), focal epilepsy-documented hippocampal sclerosis (HS) and AD (ORIVW =1.152, pIVW =.017). The causal relationship between epilepsy-documented HS and AD has been validated (ORIVW =3.994, pIVW =.027). Our MR study provides evidence for a causal relationship between focal epilepsy-documented HS and AD.

Effect of resveratrol and combination of resveratrol and donepezil on the expression of microglial cells and astrocytes in Wistar albino rats of colchicine-induced Alzheimer’s disease

AimThe goal was to evaluate the effect of resveratrol (RS) and combination therapy of RS and donepezil (DPZ), on the numerical expression of microglial cells and astrocytes, in the frontal cortex, regions of the hippocampus in colchicine-induced Alzheimer’s disease (AD) model.MethodsThe study involved male albino Wistar rats of three months, age and consisted of 6 groups, with six animals each. The immunohistochemical staining with mouse monoclonal anti-human CD 68 and mouse monoclonal anti-GFAP was performed to assess the number of microglial cells and astrocytes, respectively.ResultsAD group showed an increase in the number of microglia, and the numbers declined in the treatment groups, RS 10, RS 20, RS10/10 and DPZ + RS (p < 0.001). Astrocyte count was increased in the treatment groups in contrast to the AD group (p < 0.05). The DPZ + RS combination group revealed substantial elevation in the number of astrocytes and decreased microglial number among all the groups (p < 0.001).ConclusionRS administration has diminished the microglial number and elevated the number of astrocytes. The elevated reactive astrocytes have decreased the microglial population. However, the limitation of our study is utilizing the colchicine for the induction of neurodegeneration. Using the transgenic models of AD may give a better insight into the pathogenesis and effect of RS. Another limitation of this study is the administration of RS and DPZ through different routes. The prospects of this research include studying the probiotic nature of RS and the effect of RS in other neurodegenerative disorders.

Alzheimer's disease biomarker profiling in a memory clinic cohort without common comorbidities.

Alzheimer's disease is a multifactorial disorder with large heterogeneity. Comorbidities such as hypertension, hypercholesterolaemia and diabetes are known contributors to disease progression. However, less is known about their mechanistic contribution to Alzheimer's pathology and neurodegeneration. The aim of this study was to investigate the relationship of several biomarkers related to risk mechanisms in Alzheimer's disease with the well-established Alzheimer's disease markers in a memory clinic population without common comorbidities. We investigated 13 molecular markers representing key mechanisms underlying Alzheimer's disease pathogenesis in CSF from memory clinic patients without diagnosed hypertension, hypercholesterolaemia or diabetes nor other neurodegenerative disorders. An analysis of covariance was used to compare biomarker levels between clinical groups. Associations were analysed by linear regression. Two-step cluster analysis was used to determine patient clusters. Two key markers were analysed by immunofluorescence staining in the hippocampus of non-demented control and Alzheimer's disease individuals. CSF samples from a total of 90 participants were included in this study: 30 from patients with subjective cognitive decline (age 62.4 ± 4.38, female 60%), 30 with mild cognitive impairment (age 65.6 ± 7.48, female 50%) and 30 with Alzheimer's disease (age 68.2 ± 7.86, female 50%). Angiotensinogen, thioredoxin-1 and interleukin-15 had the most prominent associations with Alzheimer's disease pathology, synaptic and axonal damage markers. Synaptosomal-associated protein 25 kDa and neurofilament light chain were increased in mild cognitive impairment and Alzheimer's disease patients. Grouping biomarkers by biological function showed that inflammatory and survival components were associated with Alzheimer's disease pathology, synaptic dysfunction and axonal damage. Moreover, a vascular/metabolic component was associated with synaptic dysfunction. In the data-driven analysis, two patient clusters were identified: Cluster 1 had increased CSF markers of oxidative stress, vascular pathology and neuroinflammation and was characterized by elevated synaptic and axonal damage, compared with Cluster 2. Clinical groups were evenly distributed between the clusters. An analysis of post-mortem hippocampal tissue showed that compared with non-demented controls, angiotensinogen staining was higher in Alzheimer's disease and co-localized with phosphorylated-tau. The identification of biomarker-driven endophenotypes in cognitive disorder patients further highlights the biological heterogeneity of Alzheimer's disease and the importance of tailored prevention and treatment strategies.

Limbic-predominant age-related TDP43 encephalopathy (LATE) neuropathological change in neurodegenerative diseases.

TAR DNA-binding protein 43 (TDP43) is a focus of research in late-onset dementias. TDP43 pathology in the brain was initially identified in amyotrophic lateral sclerosis and frontotemporal lobar degeneration, and later in Alzheimer disease (AD), other neurodegenerative diseases and ageing. Limbic-predominant age-related TDP43 encephalopathy (LATE), recognized as a clinical entity in 2019, is characterized by amnestic dementia resembling AD dementia and occurring most commonly in adults over 80 years of age. Neuropathological findings in LATE, referred to as LATE neuropathological change (LATE-NC), consist of neuronal and glial cytoplasmic TDP43 localized predominantly in limbic areas with or without coexisting hippocampal sclerosis and/or AD neuropathological change and without frontotemporal lobar degeneration or amyotrophic lateral sclerosis pathology. LATE-NC is frequently associated with one or more coexisting pathologies, mainly AD neuropathological change. The focus of this Review is the pathology, genetic risk factors and nature of the cognitive impairments and dementia in pure LATE-NC and in LATE-NC associated with coexisting pathologies. As the clinical and cognitive profile of LATE is currently not easily distinguishable from AD dementia, it is important to develop biomarkers to aid in the diagnosis of this condition in the clinic. The pathogenesis of LATE-NC should be a focus of future research to form the basis for the development of preventive and therapeutic strategies.

Effects of Yizhi Tiaoshen acupuncture on learning and memory function and the expression of phosphorylated tau protein in the hippocampus of Alzheimer's disease model rats

To observe the effects of Yizhi Tiaoshen (benefiting mental health and regulating the spirit) acupuncture on learning and memory function, and the expression of phosphorylated tubulin-associated unit (tau) protein in the hippocampus of Alzheimer's disease (AD) model rats, and explore the effect mechanism of this therapy on AD. A blank group and a sham-operation group were randomly selected from 60 male SD rats, 10 rats in each one. AD models were established in the rest 40 rats by the intraperitoneal injection of D-galactose and okadaic acid in the CA1 region of the bilateral hippocampus. Thirty successfully-replicated model rats were randomly divided into a model group, a western medication group and an acupuncture group, 10 rats in each one. In the acupuncture group, acupuncture was applied to "Baihui" (GV 20), "Sishencong" (EX-HN 1), "Neiguan" (PC 6), "Shenmen" (HT 7), "Xuanzhong" (GB 39) and "Sanyinjiao" (SP 6); and the needles were retained for 10 min. Acupuncture was given once daily. One course of treatment was composed of 6 days, with the interval of 1 day; the completion of treatment included 4 courses. In the western medication group, donepezil hydrochloride solution (0.45 mg/kg) was administrated intragastrically, once daily; it took 7 days to accomplish one course of treatment and a completion of intervention was composed of 4 courses. Morris water maze (MWM) and novel object recognition test (NORT) were used to assess the learning and memory function of the rats. Using HE staining and Nissl staining, the morphological structure of the hippocampus was observed. With Western blot adopted, the protein expression of the tau, phosphorylated tau protein at Ser198 (p-tau Ser198), protein phosphatase 2A (PP2A) and glycogen synthase kinase-3β (GSK-3β) in the hippocampus was detected. There were no statistical differences in all of the indexes between the sham-operation group and the blank group. Compared with the sham-operation group, in the model group, the MWM escape latency was prolonged (P<0.05), the crossing frequency and the quadrant stay time in original platform were shortened (P<0.05), and the NORT discrimination index (DI) was reduced (P<0.05); the hippocampal cell numbers were declined and the cells arranged irregularly, the hippocampal neuronal structure was abnormal and the numbers of Nissl bodies decreased; the protein expression of p-tau Ser198 and GSK-3βwas increased (P<0.05) and that of PP2A decreased (P<0.05). When compared with the model group, in the western medication group and the acupuncture group, the MWM escape latency was shortened (P<0.05), the crossing frequency and the quadrant stay time in original platform were increased (P<0.05), and DI got higher (P<0.05); the hippocampal cell numbers were elevated and the cells arranged regularly, the damage of hippocampal neuronal structure was attenuated and the numbers of Nissl bodies were increased; the protein expression of p-tau Ser198 and GSK-3β was reduced (P<0.05) and that of PP2A was increased (P<0.05). There were no statistically significant differences in the above indexes between the acupuncture group and the western medication group (P>0.05). Acupuncture therapy of "benefiting mental health and regulating the spirit" could improve the learning and memory function and alleviate neuronal injure of AD model rats. The effect mechanism of this therapy may be related to the down-regulation of GSK-3β and the up-regulation of PP2A in the hippocampus, and then to inducing the inhibition of tau protein phosphorylation.

Down regulation of Akt/mTOR signaling pathway proteins in hippocampus of Alzheimer’s disease mouse model

AbstractBackgroundAkt and mechanistic target of rapamycin (mTOR) signaling pathways are implicated in AD pathology. Activation of these pathways by external cues facilitates new protein synthesis at the synapse which leads to the synaptic plasticity. We have demonstrated that activity dependent Akt1 mediated new protein synthesis is abolished in primary cortical neurons of APP/PS1 mice. However, the molecular underpinnings for the impairment of new protein synthesis at the synapse are still elusive. Our aim is to understand the molecular mechanisms prior to manifestation of pathological symptoms by examining the Akt1 and mTOR signaling cascades and new protein synthesis in hippocampus of WT and APP/PS1 male mice.MethodsWe isolated post nuclear supernatant (PNS) and synaptosomes from brain cortices of WT and APP/PS1 mice at different ages. Synaptosomes and PNS were resolved on SDS‐PAGE and immunoblotted against respective antibodies. Further, synaptoneurosomes were also prepared from hippocampus and performed 35S methionine incorporation assay without or with KCl stimulation. Statistical comparisons were performed using two‐way ANOVA followed by Tukey’s post‐hoc test or two‐tailed Mann‐Whitney U test.ResultsWe observed that pAkt1, pGSK3β, pmTOR, pS6 ribosomal protein, p4E‐BP1 levels are significantly decreased in both post nuclear supernatant (PNS) and synaptosomal fractions isolated from hippocampus of one month old (presymptomatic) APP/PS1 compared to WT male mice. Further, activity dependent new protein synthesis at the synapse was significantly impaired in synaptoneurosomes isolated from hippocampus of presymptomatic APP/PS1 mice, and this deficit is sustained at young adults (three months). However, no impairment was observed in basal protein synthesis at both ages in hippocampus of APP/PS1 compared to WT male mice. Down regulation of Akt1 precludes synaptic activity dependent protein translation at the dendrites but not in the soma in hippocampal neurons from APP/PS1 mice compared to WT mice.ConclusionsOur finding demonstrate that the dysregulation of Akt1/mTOR and its downstream signaling molecules in hippocampus contributes to synaptic dysfunction in AD through loss of activity dependent new protein synthesis at the synapse in hippocampus which is essential for synaptic plasticity and maintenance.

P.001 Application of low-intensity transcranial focused unltrasound to the hippocampus in Alzheimer’s Disease

Background: The purpose of this study was to evaluate the safety and efficacy of low-intensity tFUS under the threshold for BBB disruption in patients with AD. In addition, we assessed changes in the regional cerebral metabolic rate of glucose (rCMRglu) using F-18 fluoro-2-deoxyglucose positron emission tomography (FDG-PET) and cognitive function after tFUS. Methods: Eight AD patients were recruited. We applied low-intensity tFUS to the right hippocampus for 3 minutes using an image-guided tFUS system. For multi-modal neuroimaging guidance, MRI and CT data were spatially co-registered using the maximization of normalized mutual information. The subjectspecific coordinates of the hippocampus in the right hemisphere were identified as the tFUS target location. Results: Radiological evidence of contrast enhancement associated with BBB opening was not found in neither the visual inspection nor the ICA of the DCE-MRI data. No adverse events were observed during the hospitalization and follow-up outpatient visits for 5 to 24 months. The immediate recall and recognition memory on the SVLT were significantly improved after the sonication. The PET analysis showed the increased level of rCMRglu in the right hippocampus. Conclusions: Application of low-intensity tFUS to the hippocampus with MB did not open blood brain barrier but increased hippocampal glucose metabolism and memory function.

Region specific reduction of neurogranin immunostaining in the hippocampus of Alzheimer’s disease brains

AbstractBackgroundNeurogranin (Ng) is a post‐synaptic protein involved in formation of long‐term potentials, and thus plays an important role in learning and memory. The concentration of Ng is increased in the cerebrospinal fluid (CSF) of people with Alzheimer’s disease (AD), and CSF Ng is considered to be a biomarker for synaptic dysfunction in AD. The expression of Ng protein in the human brain and its association with AD pathology, however, are less well studied.MethodUsing immunohistochemical detection methods we investigated the protein expression of Ng, beta‐amyloid (Aβ) and hyperphosphorylated paired helical filament tau (phospho‐tau; ptau) in the post‐mortem hippocampus from 12 AD patients and 12 cognitively unaffected controls (NC). We compared the number of positively stained cells (Ng, ptau) or plaques (Aβ) in the hippocampal sub‐regions (dentate gyrus, Cornu Ammonis (CA) fields 1‐3) from the 2 groups. Donor samples with intermediate AD (i.e., Braak stage III‐IV) or NC (Braak 0‐I/II) were analyzed using Image Pro Premier automated image analysis software (version 10.01). The data were normalized to the number of cells or clusters/mm2 and analyzed using a one‐way ANOVA. Using a test of circularity (Cir = (4*A)/Pi*MaxFeret2), we further investigated morphological differences in the Ng positive neurons by measuring the Ng expression in the apical dendrite of pyramidal neurons.ResultThere was a 40% reduction of Ng immunopositive neurons in AD compared to NC in the CA3(N = 24;p = 0.0003) and in the CA1(N = 24;p = 0.014) hippocampal sub‐regions. Ng positive cells did not change significantly in AD compared to NC in the other hippocampal regions. Additionally, we showed that CA1 region, Ng was localized mainly in the neuronal cell soma of AD donors, while its expression extended into the apical dendrites of NC donors (N = 24;p = 0.006). In AD, Ng immunostaining negatively correlated with ptau immunopositive neurofibrillary tangles (r = ‐0.70;p = 0.04)ConclusionSelective loss of Ng immunostaining in certain subregions of the hippocampus suggests that synaptic damage in AD maybe a region‐specific event. The mechanism underlying such regional synaptic damage and the changes in Ng expression will be key in understanding the selective vulnerability of brain regions to AD.

Cross‐species evidence of differential expression of S100A6 and SLC11A1 in the hippocampus of Alzheimer’s disease patients and mouse models

AbstractBackgroundThe evaluation of similarities and differences between mouse models and human Alzheimer’s disease (AD) provides invaluable insights on disease pathophysiology. We compared hippocampal transcriptomic profiles of human late‐onset AD (LOAD) and early‐onset AD (EOAD) individuals with three mouse models (hAβ‐KI, APP/PS1 and 5xFAD) in an exploratory analysis. Afterwards, we validated the intersection of genes consistently altered in all groups using hippocampal tissue from APP/PS1 mice, and EOAD and LOAD patients.MethodsFive publicly available human AD/cognitively unimpaired (CU) transcriptomic profiles were collected from GEO (https://www.ncbi.nlm.nih.gov/geo/), merged and submitted to differential expression analysis (DEA) using R. APP/PS1 mouse model RNAseq data from two datasets (GSE149661 and GSE145907) were also collected. Finally, RNAseq data of 5xFAD and hAβ‐KI mouse models were obtained from AMP‐AD Knowledge Portal (https://www.synapse.org/) using synapser and synapserutils packages. All animal models were also submitted to DEA. Validation of selected genes was performed by qRT‐PCR. Target mRNA levels were normalized using β‐actin as a housekeeper gene. The results were expressed relative to wild‐type (WT) animals or CU controls using the 2−ΔΔCt method.ResultsDEA identified 1164, 3261 and 1782 differentially expressed genes (DEGs) for the comparisons between hAβ‐KI, 5xFAD and APP/PS1 mutants versus WT controls, respectively. hAβ‐KI, APP/PS1, and 5xFAD mice exhibited more DEGs in common with LOAD than with EOAD patients. Interestingly, APP/PS1 and 5xFAD mice also presented more DEGs in common with LOAD than with EOAD patients. However, 5xFAD showed significantly higher DEGs intersection with EOAD than with hAβ‐KI and APP/PS1. Additionally, we identified S100A6, C1QB, SST, CD14, CD33, SLC11A1 and KCNK1 genes altered in both EOAD and LOAD as well as the three mouse models evaluated. qRT‐PCR analysis of these genes in EOAD, LOAD and APP/PS1 model revealed S100A6 and SLC11A1 consistently altered in human pathology and mouse model.ConclusionAnimal models seek to better simulate AD pathology, making the evaluation of their molecular overlap with human disease greatly important. S100A6, a calcium‐binding protein modulating several biological activities, and SLC11A1, a metal transporter associated with inflammatory processes, were consistently altered in our transcriptomics exploratory analyses and experimental validation, making them promising targets for further investigation.