Alzheimer's disease (AD), the leading cause of dementia, is characterized by the accumulation of amyloid plaques and neurofibrillary tangles in the brain. This condition casts a significant shadow on global health due to its complex and multifactorial nature. In addition to genetic predispositions, the development of AD is influenced by a myriad of risk factors, including aging, systemic inflammation, chronic health conditions, lifestyle, and environmental exposures. Recent advancements in understanding the complex pathophysiology of AD are paving the way for enhanced diagnostic techniques, improved risk assessment, and potentially effective prevention strategies. These discoveries are crucial in the quest to unravel the complexities of AD, offering a beacon of hope for improved management and treatment options for the millions affected by this debilitating disease.
Alzheimer Disease/metabolism* ; Humans ; Animals ; Plaque, Amyloid/metabolism* ; Risk Factors

Amyloid beta (Aβ) plaques are one of the hallmarks of Alzheimer's disease (AD). However, currently available anti-amyloid therapies fail to show effectiveness in the treatment of AD in humans. It has been found that there are different types of Aβ plaque (diffuse and focal types) in the postmortem human brain. In this study, we aimed to investigate the correlations among different types of Aβ plaque and AD-related neuropathological and cognitive changes based on a postmortem human brain bank in China. The results indicated that focal plaques, but not diffuse plaques, significantly increased with age in the human hippocampus. We also found that the number of focal plaques was positively correlated with the severity of AD-related neuropathological changes (measured by the "ABC" scoring system) and cognitive decline (measured by the Everyday Cognitive Insider Questionnaire). Furthermore, most of the focal plaques were co-localized with neuritic plaques (identified by Bielschowsky silver staining) and accompanied by microglial and other inflammatory cells. Our findings suggest the potential of using focal-type but not general Aβ plaques as biomarkers for the neuropathological evaluation of AD.
Alzheimer Disease/pathology* ; Amyloid beta-Peptides/metabolism* ; Amyloid beta-Protein Precursor ; Brain/pathology* ; Cognitive Dysfunction/pathology* ; Hippocampus/metabolism* ; Humans ; Neuroinflammatory Diseases ; Plaque, Amyloid/pathology*

Alzheimer's disease (AD) is the most common neurodegenerative disorder causing dementia worldwide, and is mainly characterized by aggregated β-amyloid (Aβ). Increasing evidence has shown that plant extracts have the potential to delay AD development. The plant sterol β-Sitosterol has a potential role in inhibiting the production of platelet Aβ, suggesting that it may be useful for AD prevention. In the present study, we aimed to investigate the effect and mechanism of β-Sitosterol on deficits in learning and memory in amyloid protein precursor/presenilin 1 (APP/PS1) double transgenic mice. APP/PS1 mice were treated with β-Sitosterol for four weeks, from the age of seven months. Brain Aβ metabolism was evaluated using ELISA and Western blotting. We found that β-Sitosterol treatment can improve spatial learning and recognition memory ability, and reduce plaque load in APP/PS1 mice. β-Sitosterol treatment helped reverse dendritic spine loss in APP/PS1 mice and reversed the decreased hippocampal neuron miniature excitatory postsynaptic current frequency. Our research helps to explain and support the neuroprotective effect of β-Sitosterol, which may offer a novel pharmaceutical agent for the treatment of AD. Taken together, these findings suggest that β-Sitosterol ameliorates memory and learning impairment in APP/PS1 mice and possibly decreases Aβ deposition.
Alzheimer Disease ; Amyloid ; Animals ; Blood Platelets ; Blotting, Western ; Brain ; Cognition Disorders ; Dementia ; Dendritic Spines ; Enzyme-Linked Immunosorbent Assay ; Excitatory Postsynaptic Potentials ; Learning ; Memory ; Metabolism ; Mice ; Mice, Transgenic ; Neurodegenerative Diseases ; Neurons ; Neuroprotective Agents ; Plant Extracts ; Plants ; Plaque, Amyloid ; Spatial Learning

OBJECTIVES: Most studies of hippocampal metabolism(HM) in amnestic mild cognitive impairment(aMCI) gave inconsistent results. Our objective was to evaluate the effect of amyloid-beta(Aβ) status on hippocampal metabolism in aMCI.METHODS: Overall, 23 aMCI underwent three-dimensional magnetic resonance imaging(MRI), ¹⁸F-fluorodeoxyglucose-positron emission tomography(¹⁸FDG-PET) and ¹⁸F-Fluorbetaben amyloid positron emission tomography (amyloid-PET). According to Aβ status on amyloid PET, 23 aMCI were classified as either Aβ+aMCI(N=13) or Aβ−aMCI(N=10). The primary outcome was HM using ¹⁸FDG-PET and we investigate the difference on HM between Aβ+aMCI and Aβ−aMCI using analysis of variance(ANOVA) model, after controlling hippocampal volume.RESULTS: We found that HM was more decreased in Aβ+aMCI than Aβ−aMCI. This result was not changed after controlling hippocampal volume.CONCLUSION: Our findings suggest that Aβ+ is associated with decreased HM, regardless of hippocampal volume, in aMCI.
Amyloid ; Cognition Disorders ; Metabolism ; Pilot Projects ; Plaque, Amyloid ; Positron-Emission Tomography

OBJECTIVE: Conventional methods for organotypic hippocampal tissue slice culture (OHSC) have shown several disadvantages or limitations regarding age of animals used, duration of culture and difficulty using neurodegenerative models. Therefore, we tried to establish OHSC from old 3xTg-Alzheimer’s disease (AD) mice for longer period (over 4 weeks) and to validate utility of this system as a valid platform for translational neuroscience of AD. METHODS: OHSC was performed with old 3xTg-AD mice (12–14 months), old wild type mice (12–14 months) and young 3xTg-AD mice (2–4 months) using serum-free medium for 4 weeks. Hippocampal structure was evaluated by 4’, 6-diamidino-2-phenylindole (DAPI) intensity and neuronal metabolism was measured by Alamarblue assay. Pathologic characteristics of AD were also investigated; β-amyloid levels by ELISA, amyloid plaque deposition by Thioflavin-S staining, and glial activation by immunohistochemistry. RESULTS: Following 4-week culture in serum-free media, hippocampal cells and layers were well preserved in cultured slices from old AD mice as was in those from young AD and old wild type mice. On the contrary, excessive regression of total visible cells was observed in conventional serum-containing medium regardless of genotype of mice. In parallel with this well preserved structure, major pathologic characteristics of AD were also well manifested in hippocampal slices from old AD mice. CONCLUSION: Our findings suggest that long-term OHSC from old 3xTg-AD mouse can serve as a promising ex vivo system for studies on pathophysiology of AD, especially with the minimum number of sacrifice of experimental animals.
Alzheimer Disease ; Animals ; Culture Media, Serum-Free ; Enzyme-Linked Immunosorbent Assay ; Genotype ; Hippocampus ; Immunohistochemistry ; Metabolism ; Mice ; Neurons ; Neurosciences ; Plaque, Amyloid

OBJECTIVETo research Angelica tenuissima Nakai (ATN) for use in novel Alzheimer's disease (AD) therapeutics.

METHODSThe effect of a 30% ethanol extract of ATN (KH032) on AD-like cognitive impairment and neuropathological and neuroinflammatory changes induced by bilateral intracerebroventricular injections of β-amyloid (Aβ) peptide (Aβ) was investigated. Male C57Bl/6 mice were randomly divided into 4 groups, 10 in each group. KH032-treated groups were administrated with a low or high dose of KH032 (50 and 200 mg/kg, respectively), intragastrically for 16 days; distilled water was applied in the sham and negative groups. Open fifield test, Y maze and Morris water maze test were used for behavior test and cognitive ability. In addition, the neuroprotective effects of KH032 in Aβ-infused mice on the histopathological markers [neuronspecific nuclear protein (NeuN), Aβ] of neurodegeneration were examined. The levels of glial fibrillary acidic protein (GFAP), NeuN, phosphorylation extracellular signal-regulated kinase (ERK)/ERK, brain-derived neurotrophic factor (BDNF), phosphorylation cAMP response element-binding (CREB)/CREB protein expression were measured by Western blot.

RESULTSKH032 treatment ameliorated cognitive impairments, reduced the overexpression of Aβ, and inhibited neuronal loss and neuroinflammatory response in the Aβ-infused mice. Moreover, KH032 treatment enhanced BDNF expression levels in the hippocampus. Finally, KH032 treatment increased phosphorylation of ERK1/2 and CREB, vital for ERK-CREB signaling.

CONCLUSIONSKH032 attenuated cognitive defificits in the Aβ-infused mice by increasing BDNF expression and ERK1/2 and CREB phosphorylation and inhibiting neuronal loss and neuroinflflammatory response, suggesting that KH032 has therapeutic potential in neurodegenerative disorders such as AD.

Alzheimer Disease ; drug therapy ; pathology ; physiopathology ; Amyloid beta-Peptides ; Angelica ; chemistry ; Animals ; Brain ; pathology ; Brain-Derived Neurotrophic Factor ; metabolism ; Cognitive Dysfunction ; complications ; drug therapy ; physiopathology ; Cyclic AMP Response Element-Binding Protein ; metabolism ; Disease Models, Animal ; Male ; Maze Learning ; drug effects ; Memory, Short-Term ; drug effects ; Mice, Inbred C57BL ; Neurogenesis ; drug effects ; Neuroglia ; drug effects ; metabolism ; pathology ; Neurons ; drug effects ; metabolism ; pathology ; Neuroprotective Agents ; pharmacology ; therapeutic use ; Phosphorylation ; drug effects ; Phytotherapy ; Plant Extracts ; pharmacology ; therapeutic use ; Plaque, Amyloid ; drug therapy ; pathology ; physiopathology ; Signal Transduction ; drug effects

Alzheimer's disease (AD) is the most common form of dementia among the elderly, characterized by amyloid plaques, neurofibrillary tangles, and neuroinflammation in the brain, as well as impaired cognitive behaviors. A sex difference in the prevalence of AD has been noted, while sex differences in the cerebral pathology and relevant molecular mechanisms are not well clarified. In the present study, we systematically investigated the sex differences in pathological characteristics and cognitive behavior in 12-month-old male and female APP/PS1/tau triple-transgenic AD mice (3×Tg-AD mice) and examined the molecular mechanisms. We found that female 3×Tg-AD mice displayed more prominent amyloid plaques, neurofibrillary tangles, neuroinflammation, and spatial cognitive deficits than male 3×Tg-AD mice. Furthermore, the expression levels of hippocampal protein kinase A-cAMP response element-binding protein (PKA-CREB) and p38-mitogen-activated protein kinases (MAPK) also showed sex difference in the AD mice, with a significant increase in the levels of p-PKA/p-CREB and a decrease in the p-p38 in female, but not male, 3×Tg-AD mice. We suggest that an estrogen deficiency-induced PKA-CREB-MAPK signaling disorder in 12-month-old female 3×Tg-AD mice might be involved in the serious pathological and cognitive damage in these mice. Therefore, sex differences should be taken into account in investigating AD biomarkers and related target molecules, and estrogen supplementation or PKA-CREB-MAPK stabilization could be beneficial in relieving the pathological damage in AD and improving the cognitive behavior of reproductively-senescent females.
Alzheimer Disease ; metabolism ; pathology ; psychology ; Amyloid beta-Protein Precursor ; genetics ; metabolism ; Animals ; Cyclic AMP Response Element-Binding Protein ; metabolism ; Cyclic AMP-Dependent Protein Kinases ; metabolism ; Disease Models, Animal ; Female ; Hippocampus ; metabolism ; pathology ; Humans ; Inflammation ; metabolism ; pathology ; psychology ; Male ; Maze Learning ; physiology ; Mice, Inbred C57BL ; Mice, Transgenic ; Neurofibrillary Tangles ; metabolism ; pathology ; Plaque, Amyloid ; metabolism ; pathology ; psychology ; Presenilin-1 ; genetics ; metabolism ; Sex Characteristics ; Spatial Memory ; physiology ; p38 Mitogen-Activated Protein Kinases ; metabolism ; tau Proteins ; genetics ; metabolism

OBJECTIVETo recognize relationship of protein related neurodegeneration abnormal aggregation in the aged brains with their cognitive and motor functions.

METHODSBrain tissues from the consecutive autopsy cases of the aged from January 2005 to December 2006 in PLA General Hospital were carried out for immunohistochemical staining with beta amyloid, tau, α-synuclein and ubiquitin antibodies. The consortium to establish a registry for Alzheimer's disease (CERAD) was used to semi-quantitatively analyze Aβ positive core plaques density and Braak staging for tau positive neurofibrillary tangles (NFTs) and α-synuclein positive Lewy bodies. In addition, Aβ positive cerebral amyloid angiopathy (CAA), neuritic plaques and various ubiquitin positive structures were also observed. The relationship of these protein abnormal depositions in the aged brains with cognitive and motor functions were analyzed.

RESULTSIn brain tissues of 16 consecutive autopsy cases of the aged from 78 to 95 years, there were 13 cases with Aβ positive core plaques, their density was 2 cases with sparse, 2 cases with moderate and 9 cases with frequent, respectively, according to CREAD.Eight cases with Aβ positive CAA were found, including 6 cases of mild CAA and 2 cases of severe CAA. There were 12 cases with tau positive NFTs, including 6 cases with Braak stageI-II, 4 cases with stage III-IV and 2 cases with stage V-VI. There were 5 cases with frequent Aβ core plaques, meanwhile existing numerous tau/ubiquitin positive neuritic plaques and Braak stage IV-VI of tau positive NFTs, all of them presented cognitive dysfunction. Among 4 other cases with frequent Aβ core plaques, only one case coexisted α-synuclein positive Lewy bodies showed moderate cognitive impairment, remaining 3 cases did not present cognitive dysfunction. There were 4 cases with α-synuclein positive Lewy bodies in the brainstem, and all of these cases presented parkinsonian motor dysfunction. 13 cases with ubiquitin positive structures were found.

CONCLUSIONSBeta amyloid protein positive deposit in the aged brain is an important marker of normal brain aging and cognitive impairment; frequent Aβ core plaques in the neocortex plus Braak IV and above tau positive NFTs are closely related to cognitive dysfunction of Alzheimer's disease; α-synuclein positive Lewy bodies in the brainstem is one of the important pathological markers of parkinsonian motor disorders; ubiquitin deposition involves the development of some characteristic structures of several neurodegenerative diseases.

Aged ; Alzheimer Disease ; metabolism ; pathology ; Amyloid beta-Peptides ; analysis ; Autopsy ; Brain ; pathology ; Brain Chemistry ; Cerebral Amyloid Angiopathy ; Humans ; Neurofibrillary Tangles ; chemistry ; pathology ; Plaque, Amyloid ; Ubiquitin ; analysis ; alpha-Synuclein ; analysis ; tau Proteins ; analysis

Small ubiquitin-related modifiers (SUMOs) belong to an important class of ubiquitin like proteins. SUMOylation is a post-translational modification process that regulates the functional properties of many proteins, among which are several proteins implicated in neurodegenerative diseases. This study was aimed to investigate the changes of SUMO-1 expression and modification, and the relationship between SUMO-1 and Alzheimer's disease (AD) pathology in APP/PS1 transgenic AD mice. Using Western blot, co-immunoprecipitation and immunofluorescent staining methods, the SUMO-1 expression and modification and its relation to tau, amyloid precursor protein (APP) and β-amyloid protein (Aβ) in the 12-month-old APP/PS1 transgenic AD mice were analyzed. The results showed that: (1) Compared with the normal wild-type mice, the expression and modification of SUMO-1 increased in brain of AD mice, which was accompanied by an increase of ubiquitination; (2) In RIPA soluble protein fraction of cerebral cortex, co-immunoprecipitation analysis showed tau SUMOylated by SUMO-1 increased in AD mice, however, AT8 antibody labeled phosphorylated tau was less SUMOylated whereas PS422 antibody labeled phosphorylated tau was similar to control mice; (3) Double immunofluorescent staining showed that SUMO-1 could distributed in amyloid plaques, appearing that some of SUMO-1 diffused in centre of some plaques and some of SUMO-1 co-localized with AT8 labeled phosphorylated tau forming punctate aggregates around amyloid plaques which was concerned as dystrophic neurites, however, less Aβ, APP and PS422 labeled phosphorylated tau were found co-localized with SUMO-1. These results suggest that SUMO-1 expression and modification increase abnormally in transgenic AD mice, which may participate in modulation of the formation of senile plaques and dystrophic neurites.
Alzheimer Disease ; physiopathology ; Amyloid beta-Peptides ; metabolism ; Amyloid beta-Protein Precursor ; metabolism ; Animals ; Brain ; pathology ; Mice ; Mice, Transgenic ; Neurites ; pathology ; Phosphorylation ; Plaque, Amyloid ; physiopathology ; SUMO-1 Protein ; metabolism ; Sumoylation ; tau Proteins ; metabolism

The plant viral protease, NIa, has a strict substrate specificity for the consensus sequence of Val-Xaa-His-Gln, with a scissoring property after Gln. We recently reported that NIa efficiently cleaved the amyloid-beta (Abeta) peptide, which contains the sequence Val-His-His-Gln in the vicinity of the cleavage site by alpha-secretase, and that the expression of NIa using a lentiviral system in the brain of AD mouse model reduced plaque deposition levels. In the present study, we investigated whether exogenous expression of NIa in the brain of AD mouse model is beneficial to the improvement of cognitive deficits. To address this question, Lenti-NIa was intracerebrally injected into the brain of Tg-APPswe/PS1dE9 (Tg-APP/PS1) mice at 7 months of age and behavioral tests were performed 15-30 days afterwards. The results of the water maze test indicated that Tg-APP/PS1 mice which had been injected with Lenti-GFP showed an increased latency in finding the hidden-platform and markedly enhanced navigation near the maze-wall, and that such behavioral deficits were significantly reversed in Tg-APP/PS1 mice injected with Lenti-NIa. In the passive avoidance test, Tg-APP/PS1 mice exhibited a severe deficit in their contextual memory retention, which was reversed by NIa expression. In the marble burying test, Tg-APP/PS1 mice buried marbles fewer than non-transgenic mice, which was also significantly improved by NIa. After behavioral tests, it was verified that the Tg-APP/PS1 mice with Lenti-NIa injection had reduced Abeta levels and plaque deposition when compared to Tg-APP/PS1 mice. These results showed that the plant viral protease, NIa, not only reduces Abeta pathology, but also improves behavioral deficits.
Alzheimer Disease/*metabolism/pathology/physiopathology ; Amyloid beta-Peptides/*metabolism ; Amyloid beta-Protein Precursor/genetics ; Animals ; Avoidance Learning ; Brain/*metabolism/pathology/physiopathology ; *Cognition ; Cognition Disorders ; Disease Models, Animal ; Endopeptidases/*genetics/metabolism ; Gene Expression ; Maze Learning ; Memory ; Mice ; Mice, Inbred C57BL ; Mice, Transgenic ; Plaque, Amyloid/metabolism/*pathology ; Presenilin-1/genetics ; Viral Proteins/*genetics/metabolism