Mice ; Animals ; Alzheimer Disease/complications* ; Entorhinal Cortex/metabolism* ; Brain-Derived Neurotrophic Factor/metabolism* ; Memory Disorders/etiology* ; Thalamus/metabolism* ; Disease Models, Animal

Hyperhomocysteinemia (Hhcy) is an independent risk factor for Alzheimer's disease (AD). Visual dysfunction is commonly found and is positively correlated with the severity of cognitive defects in AD patients. Our previous study demonstrated that Hhcy induces memory deficits with AD-like tau and amyloid-β (Aβ) pathologies in the hippocampus, and supplementation with folate and vitamin B12 (FB) prevents the Hhcy-induced AD-like pathologies in the hippocampus. Here, we investigated whether Hhcy also induces AD-like pathologies in the retina and the effects of FB. An Hhcy rat model was produced by vena caudalis injection of homocysteine for 14 days, and the effects of FB were assessed by simultaneous supplementation with FB in drinking water. We found that Hhcy induced vessel damage with Aβ and tau pathologies in the retina, while simultaneous supplementation with FB remarkably attenuated the Hhcy-induced tau hyperphosphorylation at multiple AD-related sites and Aβ accumulation in the retina. The mechanisms involved downregulation of amyloid precursor protein (APP), presenilin-1, beta-site APP-cleaving enzyme 1, and protein phosphatase-2A. Our data suggest that the retina may serve as a window for evaluating the effects of FB on hyperhomocysteinemia-induced Alzheimer-like pathologies.
Alzheimer Disease ; etiology ; metabolism ; pathology ; therapy ; Amyloid beta-Peptides ; metabolism ; Animals ; Dietary Supplements ; Disease Models, Animal ; Folic Acid ; therapeutic use ; Homocysteine ; Hyperhomocysteinemia ; complications ; metabolism ; pathology ; therapy ; Male ; Rats, Sprague-Dawley ; Retina ; metabolism ; pathology ; Retinal Vessels ; metabolism ; pathology ; Vitamin B 12 ; therapeutic use ; tau Proteins ; metabolism

Alzheimer Disease ; complications ; pathology ; therapy ; Amyloid beta-Peptides ; metabolism ; Humans ; Mitochondria ; physiology ; Mitochondrial Diseases ; etiology ; tau Proteins ; metabolism

Alzheimer's disease (AD) is one of the major neurodegenerative disorders of the elderly, which is characterized by the accumulation and deposition of amyloid-beta (Aβ) peptide in human brains. Oxidative stress and neuroinflammation induced by Aβ in brain are increasingly considered to be responsible for the pathogenesis of AD. The present study aimed to determine the protective effects of walnut peptides against the neurotoxicity induced by Aβ25-35 in vivo. Briefly, the AD model was induced by injecting Aβ25-35 into bilateral hippocampi of mice. The animals were treated with distilled water or walnut peptides (200, 400 and 800 mg/kg, p.o.) for five consecutive weeks. Spatial learning and memory abilities of mice were investigated by Morris water maze test and step-down avoidance test. To further explore the underlying mechanisms of the neuroprotectivity of walnut peptides, the activities of superoxide dismutase (SOD), glutathione (GSH), acetylcholine esterase (AChE), and the content of malondialdehyde (MDA) as well as the level of nitric oxide (NO) in the hippocampus of mice were measured by spectrophotometric method. In addition, the levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β) and IL-6 in the samples were determined using ELISA. The hippocampal expressions of inducible nitric oxide synthase (iNOS) and nuclear factor κB (NF-κB) were evaluated by Western blot analysis. The results showed that walnut peptides supplementation effectively ameliorated the cognitive deficits and memory impairment of mice. Meanwhile, our study also revealed effective restoration of levels of antioxidant enzymes as well as inflammatory mediators with supplementation of walnut peptides (400 or 800 mg/kg). All the above findings suggested that walnut peptides may have a protective effect on AD by reducing inflammatory responses and modulating antioxidant system.
Acetylcholinesterase ; metabolism ; Alzheimer Disease ; drug therapy ; etiology ; Amyloid beta-Peptides ; toxicity ; Animals ; Female ; Glutathione ; metabolism ; Hippocampus ; drug effects ; metabolism ; Interleukins ; metabolism ; Juglans ; chemistry ; Male ; Malondialdehyde ; metabolism ; Maze Learning ; Memory Disorders ; drug therapy ; etiology ; Mice ; NF-kappa B ; metabolism ; Neuroprotective Agents ; pharmacology ; therapeutic use ; Nitric Oxide ; metabolism ; Peptide Fragments ; toxicity ; Peptides ; pharmacology ; therapeutic use ; Plant Extracts ; pharmacology ; therapeutic use ; Superoxide Dismutase ; metabolism ; Tumor Necrosis Factor-alpha ; metabolism

We compared the predictive ability of the various neuroimaging tools and determined the most cost-effective, non-invasive Alzheimer's disease (AD) prediction model in mild cognitive impairment (MCI) individuals. Thirty-two MCI subjects were evaluated at baseline with [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET), MRI, diffusion tensor imaging (DTI), and neuropsychological tests, and then followed up for 2 yr. After a follow up period, 12 MCI subjects converted to AD (MCIc) and 20 did not (MCInc). Of the voxel-based statistical comparisons of baseline neuroimaging data, the MCIc showed reduced cerebral glucose metabolism (CMgl) in the temporo-parietal, posterior cingulate, precuneus, and frontal regions, and gray matter (GM) density in multiple cortical areas including the frontal, temporal and parietal regions compared to the MCInc, whereas regional fractional anisotropy derived from DTI were not significantly different between the two groups. The MCIc also had lower Mini-Mental State Examination (MMSE) score than the MCInc. Through a series of model selection steps, the MMSE combined with CMgl model was selected as a final model (classification accuracy 93.8%). In conclusion, the combination of MMSE with regional CMgl measurement based on FDG-PET is probably the most efficient, non-invasive method to predict AD in MCI individuals after a two-year follow-up period.
Aged ; Alzheimer Disease/complications/*diagnosis ; Atrophy/pathology ; Biomarkers/blood ; Brain/*pathology ; Diffusion Tensor Imaging/methods ; Female ; Glucose/*metabolism ; Gray Matter/*pathology ; Humans ; Male ; Mild Cognitive Impairment/*diagnosis/etiology ; Neuroimaging/methods ; Positron-Emission Tomography/methods ; Reproducibility of Results ; Sensitivity and Specificity ; Severity of Illness Index ; White Matter/*pathology

Metabolic syndrome (MetS) is a cluster of cardiovascular risk factors that includes obesity, diabetes, and dyslipidemia. Accumulating evidence implies that MetS contributes to the development and progression of Alzheimer's disease (AD); however, the factors connecting this association have not been determined. Insulin resistance (IR) is at the core of MetS and likely represent the key link between MetS and AD. In the central nervous system, insulin plays key roles in learning and memory, and AD patients exhibit impaired insulin signaling that is similar to that observed in MetS. As we face an alarming increase in obesity and T2D in all age groups, understanding the relationship between MetS and AD is vital for the identification of potential therapeutic targets. Recently, several diabetes therapies that enhance insulin signaling are being tested for a potential therapeutic benefit in AD and dementia. In this review, we will discuss MetS as a risk factor for AD, focusing on IR and the recent progress and future directions of insulin-based therapies.
Alzheimer Disease/etiology/metabolism ; Amyloid beta-Peptides/metabolism ; Animals ; Brain/metabolism ; Cognition Disorders/*etiology/*metabolism ; Humans ; Insulin/metabolism ; *Insulin Resistance ; Metabolic Syndrome X/complications/drug therapy/*metabolism ; Molecular Targeted Therapy ; Signal Transduction/drug effects ; tau Proteins/metabolism

Alzheimer disease (AD) is a common neurodegenerative disease. Drosophila has been regard as one of the ideal models for Alzheimer because of its unique advantage on genetic manipulation. AD transgenic drosophila models not only help to elucidate the pathogenesis of Alzheimer disease, but also provide potential screening models for drugs to treat the disease. In this review, we summarize the recent research progress using AD transgenic drosophila.
Alzheimer Disease ; etiology ; genetics ; metabolism ; Amyloid beta-Peptides ; metabolism ; Animals ; Animals, Genetically Modified ; genetics ; Disease Models, Animal ; Drosophila ; genetics ; Drug Evaluation, Preclinical ; Gene Transfer Techniques ; Humans ; Phosphorylation ; tau Proteins ; metabolism

Appropriate selection and measurement of lead biomarkers of exposure are critically important for health care management purposes, public health decision making, and primary prevention synthesis. Lead is one of the neurotoxicants that seems to be involved in the etiology of psychologies. Biomarkers are generally classified into three groups: biomarkers of exposure, effect, and susceptibility.The main body compartments that store lead are the blood, soft tissues, and bone; the half-life of lead in these tissues is measured in weeks for blood, months for soft tissues, and years for bone. Within the brain, lead-induced damage in the prefrontal cerebral cortex, hippocampus, and cerebellum can lead to a variety of neurological disorders, such as brain damage, mental retardation, behavioral problems, nerve damage, and possibly Alzheimer's disease, Parkinsons disease, and schizophrenia. This paper presents an overview of biomarkers of lead exposure and discusses the neurotoxic effects of lead with regard to children and adults.
Alzheimer Disease ; chemically induced ; metabolism ; pathology ; physiopathology ; psychology ; Animals ; Behavior ; drug effects ; Biomarkers ; metabolism ; Brain ; metabolism ; pathology ; physiopathology ; Brain Diseases ; chemically induced ; pathology ; physiopathology ; Environmental Exposure ; adverse effects ; Humans ; Lead ; pharmacokinetics ; toxicity ; Lead Poisoning ; etiology ; metabolism ; pathology ; physiopathology ; psychology ; Neurotoxicity Syndromes ; etiology ; metabolism ; pathology ; physiopathology ; psychology ; Parkinson Disease, Secondary ; chemically induced ; metabolism ; pathology ; physiopathology ; psychology ; Schizophrenia ; chemically induced ; metabolism ; pathology ; physiopathology

OBJECTIVETo investigate the effects of α3 neuronal nicotinic acetylcholine receptor (nAChR) on apoptosis and p38 signal transduction pathway in SH-SY5Y cells and to assess the roles of α3 nAChR in the pathogenesis of Alzheimer's disease (AD).

METHODSThe levels of α3 nAChR mRNA and protein were measured by real-time PCR and Western blot, respectively, in SH-SY5Y cells transfected with α3 nAChR siRNA. The mRNA level of bcl-2 and bax was measured by the real-time PCR. The siRNA transfected SH-SY5Y cells and control were then treated with 10 µmol/L Aβ25-35 for another 48 h, and the change in apoptotic rate and the levels of p-p38 and p38 were measured by flow cytometry and Western blot. Subsequently these SH-SY5Y cells were exposed to a blocker of p38 protein, and the apoptotic rate was measured again.

RESULTSCompared to the controls, the expression of α3 nAChR at mRNA and protein levels in the SH-SY5Y cells transfected with α3 nAChR siRNA decreased by 95% and 86%, respectively; the mRNA levels of bax increased 2.11 times and that for bcl-2 decreased 0.53 times. The apoptotic rate was unaffected (3.40% ± 0.20%); but it increased after Aβ25-35 treatment (24.52% ± 1.59%); the level of p-p38 protein also increased by 178% in the α3 nAChR inhibited cells treated with Aβ25-35. Compared to controls, the Aβ25-35-treated SH-SY5Y cells and the Aβ25-35-treated and siRNA-transfected cells both showed a reduction in apoptosis after treatment with p38 blocker, especially in the former.

CONCLUSIONThe siRNA silencing of α3 nAChR mRNA may enhance the effect of Aβ25-35 on the cell apoptosis by increasing the levels of p38 protein and bax mRNA and decreasing the level of bcl-2 mRNA, which may play a role in the pathogenesis of AD.

Alzheimer Disease ; etiology ; Amyloid beta-Peptides ; metabolism ; Apoptosis ; Cell Line, Tumor ; Gene Silencing ; Humans ; Neuroblastoma ; metabolism ; pathology ; Peptide Fragments ; metabolism ; Proto-Oncogene Proteins c-bcl-2 ; genetics ; metabolism ; RNA, Messenger ; metabolism ; RNA, Small Interfering ; genetics ; Receptors, Nicotinic ; genetics ; metabolism ; Signal Transduction ; Transfection ; bcl-2-Associated X Protein ; genetics ; metabolism ; p38 Mitogen-Activated Protein Kinases ; metabolism

Alzheimer's disease (AD) has become one of the most important and most interesting focuses in the field of medical and scientific research. Up to now, the pathogenesis of AD has not been completely clarified. However, the high-density of amyloid β-protein (Aβ) in senile plaques of AD brain and the neurotoxicity of Aβ have been indisputable facts. The mechanisms underlying Aβ neurotoxicity are very complicated, involving calcium overload, inflammation, ion channel dysfunction, oxidative stress and so on. Among all of those, the mechanism of oxidative stress in Aβ neurotoxicity and the experimental progress of antioxidants in AD treatment have been widely reported in recent years. This review mainly discussed current research progresses on the oxidative stress of Aβ, so as to provide readers with some clues to the antioxidant therapy of AD.
Alzheimer Disease ; etiology ; metabolism ; physiopathology ; Amyloid beta-Peptides ; adverse effects ; metabolism ; Animals ; Antioxidants ; pharmacology ; Humans ; Oxidative Stress ; drug effects ; physiology