OBJECTIVE: To investigate the molecular mechanisms underlying the beneficial effect of electroacupuncture (EA) in experimental models of Alzheimer's disease (AD) in vivo. METHODS: Senescence-accelerated mouse prone 8 (SAMP8) mice were used as AD models and received EA at Yingxiang (LI 20, bilateral) and Yintang (GV 29) points for 20 days. For certain experiments, SAMP8 mice were injected intravenously with human fibrin (2 mg). The Morris water maze test was used to assess cognitive and memory abilities. The changes of tight junctions of blood-brain barrier (BBB) in mice were observed by transmission electron microscope. The expressions of fibrin, amyloid- β (Aβ), and ionized calcium-binding adapter molecule 1 (IBa-1) in mouse hippocampus (CA1/CA3) were detected by reverse transcription-quantitative polymerase chain reaction (qRT-PCR), Western blot or immunohistochemical staining. The expression of fibrin in mouse plasma was detected by enzyme-linked immunosorbent assay. The expressions of tight junction proteins zonula occludens-1 and claudin-5 in hippocampus were detected by qRT-PCR and immunofluorescence staining. Apoptosis of hippocampal neurons was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining. RESULTS: Fibrin was time-dependently deposited in the hippocampus of SAMP8 mice and this was inhibited by EA treatment (P<0.05 or P<0.01). Furthermore, EA treatment suppressed the accumulation of Aβ in the hippocampus of SAMP8 mice (P<0.01), which was reversed by fibrin injection (P<0.05 or P<0.01). EA improved SAMP8 mice cognitive impairment and BBB permeability (P<0.05 or P<0.01). Moreover, EA decreased reactive oxygen species levels and neuroinflammation in the hippocampus of SAMP8 mice, which was reversed by fibrin injection (P<0.05 or P<0.01). Mechanistically, EA inhibited the promoting effect of fibrin on the high mobility group box protein 1 (HMGB1)/toll-like receptor 4 (TLR4) and receptor for advanced glycation end products (RAGE)/nicotinamide adenine dinucleotide phosphate (NADPH) signaling pathways (P<0.01). CONCLUSION EA may potentially improve cognitive impairment in AD via inhibition of fibrin/A β deposition and deactivation of the HMGB1/TLR4 and RAGE/NADPH signaling pathways.
Mice ; Humans ; Animals ; NADP/metabolism* ; Toll-Like Receptor 4 ; HMGB1 Protein/metabolism* ; Receptor for Advanced Glycation End Products/metabolism* ; Blood-Brain Barrier/metabolism* ; Neuroinflammatory Diseases ; Electroacupuncture ; Alzheimer Disease/therapy* ; Hippocampus/metabolism* ; Amyloid beta-Peptides/metabolism*

Mutations in genes encoding amyloid precursor protein (APP) and presenilins (PSs) cause familial forms of Alzheimer's disease (AD), a neurodegenerative disorder strongly associated with aging. It is currently unknown whether and how AD risks affect early brain development, and to what extent subtle synaptic pathology may occur prior to overt hallmark AD pathology. Transgenic mutant APP/PS1 over-expression mouse lines are key tools for studying the molecular mechanisms of AD pathogenesis. Among these lines, the 5XFAD mice rapidly develop key features of AD pathology and have proven utility in studying amyloid plaque formation and amyloid β (Aβ)-induced neurodegeneration. We reasoned that transgenic mutant APP/PS1 over-expression in 5XFAD mice may lead to neurodevelopmental defects in early cortical neurons, and performed detailed synaptic physiological characterization of layer 5 (L5) neurons from the prefrontal cortex (PFC) of 5XFAD and wild-type littermate controls. L5 PFC neurons from 5XFAD mice show early APP/Aβ immunolabeling. Whole-cell patch-clamp recording at an early post-weaning age (P22-30) revealed functional impairments; although 5XFAD PFC-L5 neurons exhibited similar membrane properties, they were intrinsically less excitable. In addition, these neurons received smaller amplitude and frequency of miniature excitatory synaptic inputs. These functional disturbances were further corroborated by decreased dendritic spine density and spine head volumes that indicated impaired synapse maturation. Slice biotinylation followed by Western blot analysis of PFC-L5 tissue revealed that 5XFAD mice showed reduced synaptic AMPA receptor subunit GluA1 and decreased synaptic NMDA receptor subunit GluN2A. Consistent with this, patch-clamp recording of the evoked L23>L5 synaptic responses revealed a reduced AMPA/NMDA receptor current ratio, and an increased level of AMPAR-lacking silent synapses. These results suggest that transgenic mutant forms of APP/PS1 overexpression in 5XFAD mice leads to early developmental defects of cortical circuits, which could contribute to the age-dependent synaptic pathology and neurodegeneration later in life.
Mice ; Animals ; Alzheimer Disease/pathology* ; Amyloid beta-Peptides/metabolism* ; Receptors, N-Methyl-D-Aspartate/metabolism* ; Amyloid beta-Protein Precursor/metabolism* ; Mice, Transgenic ; Neurons/metabolism* ; Receptors, AMPA/metabolism* ; Disease Models, Animal

Resveratrol (RES), a natural polyphenolic phytochemical, has been suggested as a putative anti-aging molecule for the prevention and treatment of Alzheimer's disease (AD) by the activation of sirtuin 1 (Sirt1/Sir2). In this study, we tested the effects of RES and Sirt1/Sir2 on sleep and courtship memory in a Drosophila model by overexpression of amyloid precursor protein (APP), whose duplications and mutations cause familial AD. We found a mild but significant transcriptional increase of Drosophila Sir2 (dSir2) by RES supplementation for up to 17 days in APP flies, but not for 7 days. RES and dSir2 almost completely reversed the sleep and memory deficits in APP flies. We further demonstrated that dSir2 acts as a sleep promotor in Drosophila neurons. Interestingly, RES increased sleep in the absence of dSir2 in dSir2-null mutants, and RES further enhanced sleep when dSir2 was either overexpressed or knocked down in APP flies. Finally, we showed that Aβ aggregates in APP flies were reduced by RES and dSir2, probably via inhibiting Drosophila β-secretase (dBACE). Our data suggest that RES rescues the APP-induced behavioral deficits and Aβ burden largely, but not exclusively, via dSir2.
Animals ; Alzheimer Disease/metabolism* ; Amyloid beta-Peptides ; Amyloid beta-Protein Precursor/metabolism* ; Drosophila/physiology* ; Drosophila Proteins/metabolism* ; Resveratrol/pharmacology* ; Sirtuin 1 ; Sleep

Objective To explore the effect of knocking down Rho-associated coiled-coil kinase (ROCK2) gene on the cognitive function of amyloid precursor protein/presenilin-1 (APP/PS1) double transgenic mice and its mechanism. Methods APP/PS1 double transgenic mice were randomly divided into AD model group (AD group), ROCK2 gene knock-down group (shROCK2 group), ROCK2 gene knock-down control group (shNCgroup), and wild-type C57BL/6 mice of the same age served as the wild-type control (WT group). Morris water maze and Y maze were employed to test the cognitive function of mice. Neuron morphology was detected by Nissl staining. Immunofluorescence histochemical staining was used to detect the expression of phosphorylated dynamin-related protein 1 (p-Drp1) and mitochondrial fusion 1 (Mfn1). Western blot analysis was used to detect the expression ROCK2, cleaved-caspase-3 (c-caspase-3), B-cell lymphoma 2 (Bcl2), Bcl2-related protein X (BAX), p-Drp1, mitochondrial fission 1 (Fis1), optic atrophy 1 (OPA1), Mfn1 and Mfn2. Results Compared with AD group mice, the expression of ROCK2 in shROCK2 group mice was significantly reduced; the cognitive function was significantly improved with the number of neurons in the hippocampal CA3 and DG areas increasing, and nissl bodies were deeply stained; the expression of c-caspase-3 and BAX was decreased, while the expression of Bcl2 was increased; the expression of mitochondrial division related proteins p-Drp1 and Fis1 were decreased, while the expression of mitochondrial fusion-related proteins OPA1, Mfn1 and Mfn2 were increased. Conclusion Knock-down of ROCK2 gene can significantly improve the cognitive function and inhibit the apoptosis of nerve cells of APP/PS1 mice. The mechanism may be related to promoting mitochondrial fusion and inhibiting its division.
Animals ; Mice ; Alzheimer Disease/pathology* ; Amyloid beta-Peptides/metabolism* ; Amyloid beta-Protein Precursor ; Apoptosis/genetics* ; bcl-2-Associated X Protein ; Caspase 3 ; Cognition ; Disease Models, Animal ; Mice, Inbred C57BL ; Mice, Transgenic ; Mitochondrial Dynamics/genetics*

The physiological functions of endogenous amyloid-β (Aβ), which plays important role in the pathology of Alzheimer's disease (AD), have not been paid enough attention. Here, we review the multiple physiological effects of Aβ, particularly in regulating synaptic transmission, and the possible mechanisms, in order to decipher the real characters of Aβ under both physiological and pathological conditions. Some worthy studies have shown that the deprivation of endogenous Aβ gives rise to synaptic dysfunction and cognitive deficiency, while the moderate elevation of this peptide enhances long term potentiation and leads to neuronal hyperexcitability. In this review, we provide a new view for understanding the role of Aβ in AD pathophysiology from the perspective of physiological meaning.
Humans ; Alzheimer Disease/pathology* ; Amyloid beta-Peptides/metabolism* ; Long-Term Potentiation ; Synaptic Transmission/physiology* ; Hippocampus

Deficiencies in the clearance of peripheral amyloid β (Aβ) play a crucial role in the progression of Alzheimer's disease (AD). Previous studies have shown that the ability of blood monocytes to phagocytose Aβ is decreased in AD. However, the exact mechanism of Aβ clearance dysfunction in AD monocytes remains unclear. In the present study, we found that blood monocytes in AD mice exhibited decreases in energy metabolism, which was accompanied by cellular senescence, a senescence-associated secretory phenotype, and dysfunctional phagocytosis of Aβ. Improving energy metabolism rejuvenated monocytes and enhanced their ability to phagocytose Aβ in vivo and in vitro. Moreover, enhancing blood monocyte Aβ phagocytosis by improving energy metabolism alleviated brain Aβ deposition and neuroinflammation and eventually improved cognitive function in AD mice. This study reveals a new mechanism of impaired Aβ phagocytosis in monocytes and provides evidence that restoring their energy metabolism may be a novel therapeutic strategy for AD.
Animals ; Mice ; Alzheimer Disease ; Amyloid beta-Peptides ; Monocytes ; Cognition ; Energy Metabolism ; Phagocytosis

The multiple-step cleavage of amyloid precursor protein (APP) generates amyloid-β peptides (Aβ), highly toxic molecules causing Alzheimer's disease (AD). The nonspecific cleavage between the transmembrane region of APP (APPTM) and γ-secretase is the key step of Aβ generation. Reconstituting APPTM under physiologically-relevant conditions is crucial to investigate how it interacts with γ-secretase and for future AD drug discovery. Although producing recombinant APPTM was reported before, the large scale purification was hindered by the use of biological protease in the presence of membrane protein. Here, we expressed recombinant APPTM in Escherichia coli using the pMM-LR6 vector and recovered the fusion protein from inclusion bodies. By combining Ni-NTA chromatography, cyanogen bromide cleavage, and reverse phase high performance liquid chromatography (RP-HPLC), isotopically-labeled APPTM was obtained in high yield and high purity. The reconstitution of APPTM into dodecylphosphocholine (DPC) micelle generated mono dispersed 2D ¹⁵N-¹H HSQC spectra in high quality. We successfully established an efficient and reliable method for the expression, purification and reconstruction of APPTM, which may facilitate future investigation of APPTM and its complex in more native like membrane mimetics such as bicelle and nanodiscs.
Humans ; Amyloid beta-Protein Precursor/chemistry* ; Micelles ; Amyloid Precursor Protein Secretases/metabolism* ; Magnetic Resonance Spectroscopy ; Recombinant Proteins

Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive cognitive impairment. The main hypotheses about the pathogenesis of AD include the hypothesis of β-amyloid protein, the hypothesis of abnormal phosphorylation of Tau protein, and the hypothesis of neuroinflammation. In recent years, environmental pollutants have been considered as an important factor in causing neurological dysfunction. Common environmental pollutants include heavy metals, pesticides, polychlorinated biphenyls, microplastics, and air pollutants, all of which have been proven to have neurotoxicity. In this review, we not only discussed epidemiological and animal experimental studies that link environmental pollution with AD, but also summarized the mechanisms of action of relevant toxins, providing insights for studying the interrelationships between environmental pollutants and AD.
Animals ; Alzheimer Disease/chemically induced* ; Environmental Pollutants/toxicity* ; Neurodegenerative Diseases ; Plastics ; Amyloid beta-Peptides/metabolism*

Extracellular deposition of β-amyloid (Aβ) and intracellular hyperphosphorylated tau are the predominant pathological changes in Alzheimer's disease (AD). Increasing evidence demonstrates a critical role of a variety of small GTPases, namely Ras-related proteins (Rabs), in the pathogenesis of AD. As crucial regulators of intracellular membrane trafficking, alteration in Rab protein expression and function represents one of the primary factors contributing to the abnormal membrane trafficking in AD. Additionally, the Rab GTPases are also involved in the development of Aβ, tau and other pathological changes associated with AD. In this article, we conduct a comprehensive review on the primary functions of multiple Rab proteins and their involvement in the pathogenesis of AD.
Humans ; Alzheimer Disease ; rab GTP-Binding Proteins/metabolism* ; Amyloid beta-Peptides/metabolism* ; tau Proteins/metabolism*

OBJECTIVE: To explore whether the protein Deglycase protein 1 (DJ1) can ameliorate Alzheimer's disease (AD)-like pathology in Amyloid Precursor Protein/Presenilin 1 (APP/PS1) double transgenic mice and its possible mechanism to provide a theoretical basis for exploring the pathogenesis of AD. METHODS: Adeno-associated viral vectors (AAV) of DJ1-overexpression or DJ1-knockdown were injected into the hippocampus of 7-month-old APP/PS1 mice to construct models of overexpression or knockdown. Mice were divided into the AD model control group (MC), AAV vector control group (NC), DJ1-overexpression group (DJ1 ⁺), and DJ1-knockdown group (DJ1 ^-). After 21 days, the Morris water maze test, immunohistochemistry, immunofluorescence, and western blotting were used to evaluate the effects of DJ1 on mice. RESULTS: DJ1 ⁺ overexpression decreased the latency and increased the number of platform traversals in the water maze test. DJ1 ^- cells were cured and atrophied, and the intercellular structure was relaxed; the number of age spots and the expression of AD-related proteins were significantly increased. DJ1 ⁺ increased the protein expression of Nuclear factor erythroid 2-related factor 2 (NRF2), heme oxygenase-1 (HO-1), light chain 3 (LC3), phosphorylated AMPK (p-AMPK), and B cell lymphoma-2 (BCL-2), as well as the antioxidant levels of total superoxide dismutase (T-SOD), total antioxidant capacity (T-AOC), and Glutathione peroxidase (GSH-PX), while decreasing the levels of Kelch-like hydrates-associated protein 1 (Keap1), mammalian target of rapamycin (mTOR), p62/sequestosome1 (p62/SQSTM1), Caspase3, and malondialdehyde (MDA). CONCLUSION DJ1-overexpression can ameliorate learning, memory, and AD-like pathology in APP/PS1 mice, which may be related to the activation of the NRF2/HO-1 and AMPK/mTOR pathways by DJ1.
Animals ; Mice ; Alzheimer Disease/therapy* ; AMP-Activated Protein Kinases/metabolism* ; Amyloid beta-Protein Precursor/metabolism* ; Antioxidants/metabolism* ; Disease Models, Animal ; Hippocampus/metabolism* ; Kelch-Like ECH-Associated Protein 1/metabolism* ; Mammals/metabolism* ; Mice, Inbred C57BL ; Mice, Transgenic ; NF-E2-Related Factor 2/metabolism* ; Presenilin-1/metabolism* ; TOR Serine-Threonine Kinases/metabolism*