[Abstract Title]. - Society for Neuroscience

NIH Grant NS43946
NIH Grant AG 027465:01A2
NIH Grant AG 5AG016570
Alzheimer's Association NIRG-03-6103
Title: Elevated levels of soluble Aβ oligomers and Aβ42 in cortical synapses of late stage
Alzheimer‟s disease
Authors: *S. SOKOLOW 1 , A. J. HEADLEY 1 , K. E. BLAKELY 1 , C. A. MILLER 3 , H. V.
VINTERS 4 , G. M. COLE 5 , K. H. GYLYS 2 ;
1 Sch. of Nursing, 2 Brain Res. Inst. and Sch. of Nursing, UCLA, Los Angeles, CA; 3 Dept. of
Pathology and Neurol., Keck Sch. of Med. of USC, Los Angeles, CA; 4 Dept. of Pathology and
Lab. Med., UCLA Sch. of Med., Los Angeles, CA; 5 Sch. of Med. and Sepulveda VAMC
GRECC, UCLA and Sepulveda VA Med. Ctr., Los Angeles, CA
Abstract: Although fibrillar amyloid beta (Aβ) is the major component of senile plaques in
Alzheimer‟s disease (AD), new evidence suggests that accumulation of soluble Aβ oligomers is
the proximal cause of synapse dysfunction in AD. Thus accurate identification and quantification
of Aβ species in AD synapses are crucial steps to elucidate Aβ toxicity in AD pathogenesis. In
order to study synaptic changes in AD, our laboratory has developed methods for flow cytometry
analysis of synaptosomes prepared from cryopreserved human tissue. Our previous results in AD
synaptosomes showed a high correlation between flow quantification of Aβ and different Aβ
assembly states identified by Western blot. The present study quantifies three Aβ species (Aβ40,
Aβ42 and Aβ oligomers) in late AD cases (Braak & Braak score V and VI), with specific beadbased
immunoassays using the xMAP ® technology (Luminex ® , Austin, Texas). We addressed
Aβ solubility in AD synapses by performing serial protein extractions of human cryoprotected
synaptosomes (crude P2) isolated from post-mortem parietal cortex (A39): i) P2 proteins were
extracted by sonication in a detergent-free buffer followed by centrifugation at 26,000 g and ii)
the remaining pellet was extracted twice by sonication in 1% N-lauroylsarcosyl (NLS) sucrose
followed by centrifugation at 300,000 g. Levels of Aβ oligomers (aggregated Aβ), Aβ42 and
Aβ40 were measured in each fraction using specific assays developed for the Luminex ® xMAP ®
platform (Invitrogen, Camarillo). Our results showed significantly elevated synaptic levels of
soluble Aβ oligomers in the detergent-free extracts of AD synaptosomes compared to normal.
The levels of Aβ oligomers were undetectable in extracts of control patients (n = 2) and 57.57 ±
25.17 pg/κg in AD (mean ± SD, n = 7, p