Docosahexaenoic acid disrupts in vitro amyloid beta(1-40) fibrillation and concomitantly inhibits amyloid levels in cerebral cortex of Alzheimer's disease model rats.
We have previously reported that dietary docosahexaenoic acid (DHA) improves and/or protects against impairment of cognition ability in amyloid beta(1-40) (Abeta(1-40))-infused Alzheimer's disease (AD)-model rats. Here, after the administration of DHA to AD model rats for 12 weeks, the levels of Abeta(1-40), cholesterol and the composition of fatty acids were investigated in the Triton X100-insoluble membrane fractions of their cerebral cortex. The effects of DHA on the in vitro formation and kinetics of fibrillation of Abeta(1-40) were also investigated by thioflavin T fluorescence spectroscopy, transmission electron microscopy and fluorescence microscopy. Dietary DHA significantly decreased the levels of Abeta(1-40), cholesterol and saturated fatty acids in the detergent insoluble membrane fractions of AD rats. The formation of Abeta fibrils was also attenuated by their incubation with DHA, as demonstrated by the decreased intensity of thioflavin T-derived fluorescence and by electron micrography. DHA treatment also decreased the intensity of thioflavin fluorescence in preformed-fibril Abeta peptides, demonstrating the anti-amyloidogenic effects of DHA. We then investigated the effects of DHA on the levels of oligomeric amyloid that is generated during its in vitro transformation from monomers to fibrils, by an anti-oligomer-specific antibody and non-reducing Tris-Glycine gradient (4-20%) gel electrophoresis. DHA concentration-dependently reduced the levels of oligomeric amyloid species, suggesting that dietary DHA-induced suppression of in vivo Abeta(1-40) aggregation occurs through the inhibitory effect of DHA on oligomeric amyloid species.
Hashimoto
Michio
M
Department of Environmental Physiology, Shimane University Faculty of Medicine, Izumo, Shimane, Japan. michio1@med.shimane-u.ac.jp
Shahdat
Hossain Md
HM
Yamashita
Shinji
S
Katakura
Masanori
M
Tanabe
Yoko
Y
Fujiwara
Hironori
H
Gamoh
Shuji
S
Miyazawa
Teruo
T
Arai
Hiroyuki
H
Shimada
Toshio
T
Shido
Osamu
O
D000544:Alzheimer Disease / Q000139:chemically induced / Q000178:diet therapy / Q000473:pathology; D016229:Amyloid beta-Peptides / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D000906:Antibodies / Q000008:administration & dosage; D052160:Benzothiazoles; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D002784:Cholesterol / Q000378:metabolism; D004195:Disease Models, Animal; D004281:Docosahexaenoic Acids / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D046529:Microscopy, Electron, Transmission / Q000379:methods; D016874:Neurofibrillary Tangles / Q000187:drug effects* / Q000473:pathology / Q000648:ultrastructure; D010446:Peptide Fragments / Q000276:immunology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013844:Thiazoles
D016229:Amyloid beta-Peptides; D000906:Antibodies; D052160:Benzothiazoles; D010446:Peptide Fragments; D013844:Thiazoles; C078592:amyloid beta-protein (1-40); C009462:thioflavin T; D004281:Docosahexaenoic Acids; D002784:Cholesterol