Beta Amyloid Deposition: Amyloid Deposition: Reserach Papers on Amyloid Peptides Deposition

Beta Amyloid Deposition: Amyloid Deposition: Reserach Papers on Amyloid Peptides Deposition

Nunes AF, Montero M, Franquinho F, Santos SD, Malva J, Zimmer J, Sousa MM. Transthyretin knockout mice display decreased susceptibility to AMPA-induced neurodegeneration. Neurochem Int. 2009 Dec;55(7):454-7. PubMed Abstract

Transthyretin (TTR) has been regarded as a neuroprotective protein given that TTR knockout (KO) mice display increased susceptibility for amyloid beta deposition and memory deficits during aging. In parallel, TTR KO mice have increased levels of neuropeptide Y (NPY), which promotes neuroprotection and neuroproliferation. In this work, we aimed at evaluating TTR neuroprotective effect against an excitotoxic insult that is known to be prevented by NPY action. We show that despite a putative neuroprotective role of TTR, hippocampal slice cultures from TTR KO mice display a decreased susceptibility to AMPA-induced neurodegeneration. We also suggest that increased NPY levels in TTR KO mice are not associated with increased cell proliferation in the dentate gyrus or subventricular zone. In summary, the alleged neuroprotective role of TTR in the nervous system should be regarded with caution and should not be generalized to all types of insults.

Lin MS, Chen XB, Wang SS, Chang Y, Chen WY. Dynamic fluorescence imaging analysis to investigate the cholesterol recruitment in lipid monolayer during the interaction between beta-amyloid (1-40) and lipid monolayers. Colloids Surf B Biointerfaces. 2009 Nov 1;74(1):59-66. PubMed Abstract

Extracellular beta-amyloid (Abeta) deposit is considered as one of the primary factors in inducing Alzheimer's disease (AD). However, the mechanism of Abeta deposition on the cell membrane and the induced cytotoxicity are still unclear. On the basis of the previous reports and results, we propose the "Recruiting Hypothesis" on the interaction between the plasma membrane and Abeta. Recently, many studies focused on cholesterol, which is considered as an important factor for AD. The most challenging issue in studying the cholesterol is non-ideal mixing behavior and non-dynamic analysis. In the present study, we investigated the cholesterol recruitment in the lipid monolayer during the interaction between beta-amyloid peptides Abeta (1-40) and lipid monolayers by dynamic fluorescent imaging analysis. Results from lipid monolayer trough studies showed that the rate of Abeta adsorption onto lipid monolayer is mainly due to the electrostatic effect which is sensitive to the lipid monolayer composition. From the fluorescence imaging analysis, the interaction of Abeta with lipid monolayer containing negative charge lipid and cholesterol brings out the recruiting behavior of the cholesterol and reduces the fluidity of lipid. The present study not only demonstrates the technical application for monitoring the dynamic molecular behaviors at the interface but also reveals the roles to distinguish lipid molecules on the Abeta-membrane interaction.

Mouton PR, Chachich ME, Quigley C, Spangler E, Ingram DK. Caloric restriction attenuates amyloid deposition in middle-aged dtg APP/PS1 mice. Neurosci Lett. 2009 Oct 30;464(3):184-7. PubMed Abstract

Caloric restriction (CR) mitigates neurological damage arising from aging and a variety of other sources, including neuropathology in young adult mice that express single and double transgenic (tg) mutations associated with Alzheimer disease (AD). To evaluate the potential of CR to protect against relatively heavy AD-type pathology, middle-aged (13-14-month-old) mice that co-express two mutations related to familial AD, amyloid precursor protein (APP) and presenilin 1 (PS1), were fed balanced diets with 40% fewer calories than ad libitum-fed controls. Following 18 weeks of treatment, mice were killed and brains were processed for quantification of total volume of amyloid-beta (Abeta) in the hippocampal formation and the overlying neocortex. Computerized stereology confirmed that CR reduced the total Abeta volume by about one-third compared to that in age-matched controls. Thus, CR appears to attenuate the accumulation of AD-type neuropathology in two cortical brain regions of middle-aged dtg APP/PS1 mice. These findings support the view that CR could be a potentially effective, non-pharmacology strategy for reducing relatively heavy Abeta deposition in older adult dtg APP/PS1 mice, and possibly afford similar protection against the onset and progression of AD in older adult humans.

Morita M, Osoda K, Yamazaki M, Shirai F, Matsuoka N, Arakawa H, Nishimura S. Effects of non-steroidal anti-inflammatory drugs on Abeta deposition in Abeta(1-42) transgenic C. elegans. Brain Res. 2009 Oct 27;1295:186-91. PubMed Abstract

Although epidemiological studies have shown that long-term treatment with non-steroidal anti-inflammatory drugs (NSAIDs) may protect against Alzheimer's disease (AD), the mechanism(s) by which NSAIDs reduce the risk of AD remain to be determined. As C. elegans possess neither inflammatory cells nor the arachidonate cascade, we could evaluate the effects of NSAIDs on amyloid beta (Abeta) deposition in the absence of immune cells using Abeta-transgenic C. elegans. For this purpose, we established a strain of Abeta-transgenic C. elegans in which thioflavin S-reactive deposits are reproducibly detectable by confocal microscopy. Among the NSAIDs examined, ibuprofen and naproxen reduced the number of thioflavin S-reactive deposits. Furthermore, ibuprofen and naproxen neither affect the thioflavin S binding to Abeta nor Abeta expression in transgenic C. elegans. These data suggest that ibuprofen and naproxen, the most frequently used NSAIDs for the treatment of AD, have an inhibitory effect on Abeta deposition that is independent of the arachidonate cascade and cellular immune systems.

Kitaguchi H, Tomimoto H, Ihara M, Shibata M, Uemura K, Kalaria RN, Kihara T, Asada-Utsugi M, Kinoshita A, Takahashi R. Chronic cerebral hypoperfusion accelerates amyloid beta deposition in APPSwInd transgenic mice. Brain Res. 2009 Oct 19;1294:202-10. PubMed Abstract

Chronic cerebral ischemia may accelerate clinicopathological changes in Alzheimer's disease. We have examined whether chronic cerebral hypoperfusion accelerates amyloid beta deposition in amyloid protein precursor transgenic (APP-Tg) mouse. At 5, 8, and 11 months of age, C57Bl/6J male mice overexpressing a mutant form of the human APP bearing the both Swedish (K670N/M671L) and the Indiana (V717F) mutations (APPSwInd) and their litterrmates were subjected to either sham operation or bilateral carotid artery stenosis (BCAS) using microcoils with an internal diameter of 0.18 mm (short-period group). One month after the sham operation or BCAS, these animals were examined by immunohistochemistry for glial fibrillary acidic protein, amyloid beta(1-40) (Abeta(1-40)), amyloid beta(1-42) (Abeta(1-42)), as well as Western blotting and filter assay for Abeta. Another batch of the littermates of APPSwInd mice were subjected to either sham operation or BCAS at 3 months and were examined in the same manner after survival for 9 months (long-period group). In the BCAS-treated group, the white matter was rarefied and astroglia was proliferated. Amyloid beta(1-40) immunoreactivity was found in a few axons in the white matter after BCAS, whereas Abeta(1-42) was accumulated in the scattered cortical neurons and the axons at ages of 6 months and thereafter in the short- and long-period groups. In the neuropil, both Abeta(1-40) and Abeta(1-42) were deposited in the sham-operated and BCAS-treated mice at ages of 9 and 12 months. There were no differences between the short-period group at ages of 12 months and the long-period group. Filter assay showed an increase of Abeta fibrils in the extracellular enriched fraction. Taken together, chronic cerebral hypoperfusion increased Abeta fibrils and induced Abeta deposition in the intracellular compartment and, therefore, may accelerate the pathological changes of Alzheimer's disease.

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