Learning Deficits Accompanied by Microglial Proliferation After the Long-Term Post-Injection of Alzheimer’s Disease Brain Extract in Mouse Brains

2021 ◽  
Vol 79 (4) ◽  
pp. 1701-1711
Author(s):  
Tetsuo Hayashi ◽  
Shotaro Shimonaka ◽  
Montasir Elahi ◽  
Shin-Ei Matsumoto ◽  
Koichi Ishiguro ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Brain ◽  
Functional Decline ◽  
Brain Regions ◽  
Insoluble Fraction ◽  
Brain Extract ◽  
Post Injection ◽  
Learning Deficits

Background: Human tauopathy brain injections into the mouse brain induce the development of tau aggregates, which spread to functionally connected brain regions; however, the features of this neurotoxicity remain unclear. One reason may be short observational periods because previous studies mostly used mutated-tau transgenic mice and needed to complete the study before these mice developed neurofibrillary tangles. Objective: To examine whether long-term incubation of Alzheimer’s disease (AD) brain in the mouse brain cause functional decline. Methods: We herein used Tg601 mice, which overexpress wild-type human tau, and non-transgenic littermates (NTg) and injected an insoluble fraction of the AD brain into the unilateral hippocampus. Results: After a long-term (17–19 months) post-injection, mice exhibited learning deficits detected by the Barnes maze test. Aggregated tau pathology in the bilateral hippocampus was more prominent in Tg601 mice than in NTg mice. No significant changes were observed in the number of Neu-N positive cells or astrocytes in the hippocampus, whereas that of Iba-I-positive microglia increased after the AD brain injection. Conclusion: These results potentially implicate tau propagation in functional decline and indicate that long-term changes in non-mutated tau mice may reflect human pathological conditions.

scholarly journals Emerging Link between Alzheimer’s Disease and Homeostatic Synaptic Plasticity

2016 ◽  
Vol 2016 ◽  
pp. 1-19 ◽  
Author(s):  
Sung-Soo Jang ◽  
Hee Jung Chung
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Synaptic Plasticity ◽  
Senile Plaques ◽  
Long Term Potentiation ◽  
Brain Regions ◽  
Synaptic Activity ◽  
Homeostatic Plasticity ◽  
Brain Disorder

Alzheimer’s disease (AD) is an irreversible brain disorder characterized by progressive cognitive decline and neurodegeneration of brain regions that are crucial for learning and memory. Although intracellular neurofibrillary tangles and extracellular senile plaques, composed of insoluble amyloid-β(Aβ) peptides, have been the hallmarks of postmortem AD brains, memory impairment in early AD correlates better with pathological accumulation of soluble Aβoligomers and persistent weakening of excitatory synaptic strength, which is demonstrated by inhibition of long-term potentiation, enhancement of long-term depression, and loss of synapses. However, current, approved interventions aiming to reduce Aβlevels have failed to retard disease progression; this has led to a pressing need to identify and target alternative pathogenic mechanisms of AD. Recently, it has been suggested that the disruption of Hebbian synaptic plasticity in AD is due to aberrant metaplasticity, which is a form of homeostatic plasticity that tunes the magnitude and direction of future synaptic plasticity based on previous neuronal or synaptic activity. This review examines emerging evidence for aberrant metaplasticity in AD. Putative mechanisms underlying aberrant metaplasticity in AD will also be discussed. We hope this review inspires future studies to test the extent to which these mechanisms contribute to the etiology of AD and offer therapeutic targets.

scholarly journals Evaluation of Imaging Windows for Tau PET Imaging Using 18F-PI2620 in Cognitively Normal Individuals, Mild Cognitive Impairment, and Alzheimer’s Disease Patients

2020 ◽  
Vol 19 ◽  
pp. 153601212094758 ◽  
Author(s):  
Chanisa Chotipanich ◽  
Monchaya Nivorn ◽  
Anchisa Kunawudhi ◽  
Chetsadaporn Promteangtrong ◽  
Natphimol Boonkawin ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Standardized Uptake Value ◽  
Brain Regions ◽  
Post Injection ◽  
Cognitively Normal ◽  
Scanning Time ◽  
Normal Individuals

Background: The study aimed to evaluate the appropriate uptake-timing in cognitively normal individuals, mild cognitive impairment (MCI), and Alzheimer’s disease (AD) patients, using 18F-PI 2620 dynamic PET acquisition. Methods: Thirty-four MCI patients, 6 AD patients, and 24 cognitively normal individuals were enrolled in this study. A dynamic 18F-PI 2620 PET study was conducted at 30-75 minutes post-injection in these groups. Co-registration was applied between the dynamic acquisition PET and T1-weighted MRI to delineate various cortical regions. The standardized uptake value ratio (SUVR) was used for quantitative analysis. P-mod software with the Automated Anatomical Labeling (AAL)-merged atlas was employed to generate automatic volumes of interest for 11 brain regions. Results: The curves in most brain regions presented an average SUVR stability at 30-40 minutes post-injection in each group. The appropriate uptake-timing interval of 18F-PI 2620 was 30-75 minutes post injection for AD group and 30-40 minutes post injection for both cognitively normal individuals and MCI groups. Conclusion: Short uptake time around 30-40 minutes post-injection would be more comfortable and convenient for all patients, especially in those with dementia who were unable to stay motionless for long periods of scanning time in the scanner.

Intranasal formulation of erythropoietin (EPO) showed potent protective activity against amyloid toxicity in the Aβ25-35 non-transgenic mouse model of Alzheimer’s disease

2013 ◽  
Vol 27 (11) ◽  
pp. 1044-1057 ◽  
Author(s):  
Tangui Maurice ◽  
Muhammad-Hariri Mustafa ◽  
Catherine Desrumaux ◽  
Emeline Keller ◽  
Gaëlle Naert ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cell Loss ◽  
Neuroprotective Activity ◽  
Learning Deficits ◽  
Akt Activation ◽  
Amyloid Toxicity ◽  
Model Of Alzheimer’S Disease ◽  
Short And Long Term

Erythropoietin (EPO) promotes neurogenesis and neuroprotection. We here compared the protection induced by two EPO formulations in a rodent model of Alzheimer’s disease (AD): rHu-EPO and a low sialic form, Neuro-EPO. We used the intracerebroventricular administration of aggregated Aβ25-35 peptide, a non-transgenic AD model. rHu-EPO was tested at 125–500 µg/kg intraperitoneally and Neuro-EPO at 62–250 µg/kg intranasally (IN). Behavioural procedures included spontaneous alternation, passive avoidance, water-maze and object recognition, to address spatial and non-spatial, short- and long-term memories. Biochemical markers of Aβ25-35 toxicity in the mouse hippocampus were examined and cell loss in the CA1 layer was determined. rHu-EPO and Neuro-EPO led to a significant prevention of Aβ25-35-induced learning deficits. Both EPO formulations prevented the induction of lipid peroxidation in the hippocampus, showing an antioxidant activity. rHu-EPO (250 µg/kg) or Neuro-EPO (125 µg/kg) prevented the Aβ25-35-induced increase in Bax level, TNFα and IL-1β production and decrease in Akt activation. A significant prevention of the Aβ25-35-induced cell loss in CA1 was also observed. EPO is neuroprotective in the Aβ25-35 AD model, confirming its potential as an endogenous neuroprotection system that could be boosted for therapeutic efficacy. We here identified a new IN formulation of EPO showing high neuroprotective activity. Considering its efficacy, ease and safety, IN Neuro-EPO is a new promising therapeutic agent in AD.

scholarly journals Conjugates of neuroprotective chaperone L-PGDS provide MRI contrast for detection of amyloid β-rich regions in live Alzheimer’s Disease mouse model brain

2020 ◽  
Author(s):  
Bhargy Sharma ◽  
Joanes Grandjean ◽  
Margaret Phillips ◽  
Ambrish Kumar ◽  
Francesca Mandino ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Model ◽  
Mouse Brain ◽  
Amyloid Fibrils ◽  
Amyloid Β ◽  
Brain Regions ◽  
Mri Contrast ◽  
Neuroprotective Function

AbstractEndogenous brain proteins can recognize the toxic oligomers of amyloid-β (Aβ) peptides implicated in Alzheimer’s disease (AD) and interact with them to prevent their aggregation. Lipocalin-type Prostaglandin D Synthase (L-PGDS) is a major Aβ-chaperone protein in the human cerebrospinal fluid. Here we demonstrate that L-PGDS detects amyloids in diseased mouse brain. Conjugation of L-PGDS with magnetic nanoparticles enhanced the contrast for magnetic resonance imaging. We conjugated the L-PGDS protein with ferritin nanocages to detect amyloids in the AD mouse model brain. We show here that the conjugates administered through intraventricular injections co-localize with amyloids in the mouse brain. These conjugates can target the brain regions through non-invasive intranasal administration, as shown in healthy mice. These conjugates can inhibit the aggregation of amyloids in vitro and show potential neuroprotective function by breaking down the mature amyloid fibrils.

Clinical and biological effects of long-term lithium treatment in older adults with amnestic mild cognitive impairment: randomised clinical trial

2019 ◽  
Vol 215 (5) ◽  
pp. 668-674 ◽  
Author(s):  
Orestes V. Forlenza ◽  
Márcia Radanovic ◽  
Leda L. Talib ◽  
Wagner F. Gattaz
Keyword(s):  
Alzheimer’S Disease ◽  
Older Adults ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Lithium Treatment ◽  
Functional Decline ◽  
Amnestic Mild Cognitive Impairment ◽  
Community Dwelling

BackgroundExperimental studies indicate that lithium may facilitate neurotrophic/protective responses in the brain. Epidemiological and imaging studies in bipolar disorder, in addition to a few trials in Alzheimer's disease support the clinical translation of these findings. Nonetheless, there is limited controlled data about potential use of lithium to treat or prevent dementia.AimsTo determine the benefits of lithium treatment in patients with amnestic mild cognitive impairment (MCI), a clinical condition associated with high risk for Alzheimer's disease.MethodA total of 61 community-dwelling, physically healthy, older adults with MCI were randomised to receive lithium or placebo (1:1) for 2 years (double-blind phase), and followed-up for an additional 24 months (single-blinded phase) (trial registration at clinicaltrials.gov: NCT01055392). Lithium carbonate was prescribed to yield subtherapeutic concentrations (0.25–0.5 mEq/L). Primary outcome variables were the cognitive (Alzheimer's Disease Assessment Scale – cognitive subscale) and functional (Clinical Dementia Rating – Sum of Boxes) parameters obtained at baseline and after 12 and 24 months. Secondary outcomes were neuropsychological test scores; cerebrospinal fluid (CSF) concentrations of Alzheimer's disease-related biomarkers determined at 0, 12 and 36 months; conversion rate from MCI to dementia (0–48 months).ResultsParticipants in the placebo group displayed cognitive and functional decline, whereas lithium-treated patients remained stable over 2 years. Lithium treatment was associated with better performance on memory and attention tests after 24 months, and with a significant increase in CSF amyloid-beta peptide (Aβ1−42) after 36 months.ConclusionsLong-term lithium attenuates cognitive and functional decline in amnestic MCI, and modifies Alzheimer's disease-related CSF biomarkers. The present data reinforces the disease-modifying properties of lithium in the MCI–Alzheimer's disease continuum.Declaration of interestNone.

Psychotic Symptoms in Alzheimer's Disease Are Not Associated With More Severe Neuropathologic Features

2000 ◽  
Vol 12 (4) ◽  
pp. 547-558 ◽  
Author(s):  
Robert A. Sweet ◽  
Ronald L. Hamilton ◽  
Oscar L. Lopez ◽  
William E. Klunk ◽  
Stephen R. Wisniewski ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Functional Decline ◽  
Neurofibrillary Tangle ◽  
Temporal Cortex ◽  
Lewy Bodies ◽  
Occipital Cortex ◽  
Brain Regions ◽  
Neuritic Plaque ◽  
Psychotic Symptoms

Psychotic symptoms in Alzheimer's disease (AD) have been associated with increased rates of cognitive impairment and functional decline. Prior studies have been conflicting with regard to whether AD patients with psychosis (AD+P) have evidence of more severe neuropathologic findings at postmortem exam. We examined the severity of neuritic plaques and neurofibrillary tangles in six brain regions—middle frontal cortex, hippocampus, inferior parietal cortex, superior temporal cortex, occipital cortex, and transentorhinal cortex—in 24 AD+P subjects and 25 matched AD subjects without psychosis (AD-P). All analyses controlled for the presence of cortical Lewy bodies, and corrected for multiple comparisons. We found no significant associations between neuritic plaque and neurofibrillary tangle severity and AD+P, and no significant associations with any individual psychotic symptom. The association of AD+P with a more rapidly progressive course of AD appears to be mediated by a neuropathologic process other than increased severity of plaque and tangle formation.

scholarly journals Neurotransmitter receptor and time dependence of the synaptic plasticity disrupting actions of Alzheimer's disease Aβ in vivo

2014 ◽  
Vol 369 (1633) ◽  
pp. 20130147 ◽  
Author(s):  
Igor Klyubin ◽  
Tomas Ondrejcak ◽  
Jennifer Hayes ◽  
William K. Cullen ◽  
Alexandra J. Mably ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Synaptic Plasticity ◽  
Synaptic Function ◽  
Water Soluble ◽  
Brain Extract ◽  
Amyloid Β Protein ◽  
Duration Of Action ◽  
The Impact

Many endogenous factors influence the time course and extent of the detrimental effects of amyloid β-protein (Aβ) on synaptic function. Here, we assessed the impact of varying endogenous glutamatergic and cholinergic transmission by pharmacological means on the disruption of plasticity at hippocampal CA3-to-CA1 synapses in the anaesthetized rat. NMDA receptors (NMDARs) are considered critical in mediating Aβ-induced inhibition of long-term potentiation (LTP). However, intracerebroventricular injection of Aβ 1–42 inhibited not only NMDAR-dependent LTP but also voltage-activated Ca 2+ -dependent LTP induced by strong conditioning stimulation during NMDAR blockade. On the other hand, another form of NMDAR-independent synaptic plasticity, endogenous acetylcholine-induced muscarinic receptor-dependent long-term enhancement, was not hindered by Aβ 1–42 . Interestingly, augmenting endogenous acetylcholine activation of nicotinic receptors prior to the injection of Aβ 1–42 prevented the inhibition of NMDAR-dependent LTP, whereas the same intervention when introduced after the infusion of Aβ was ineffective. We also examined the duration of action of Aβ, including water soluble Aβ from Alzheimer's disease (AD) brain. Remarkably, the inhibition of LTP induction caused by a single injection of sodium dodecyl sulfate-stable Aβ dimer-containing AD brain extract persisted for at least a week. These findings highlight the need to increase our understanding of non-NMDAR mechanisms and of developing novel means of overcoming, rather than just preventing, the deleterious synaptic actions of Aβ.

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