ISSN:
1460-9568
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
In order to investigate the possible links connecting β-amyloid (Aβ) accumulation, τ-hyperphosphorylation and nicotinic receptor expression, rat embryonic primary hippocampal cultures were incubated with amyloidogenic peptides. Exposure to 0.5 µm fibrillar Aβ1−42 for 3 days caused retraction of dendrites, shrinkage of cell bodies and a decrease in the expression of microtubule-associated proteins 2b (MAP2b), without affecting the total number of neurons and their viability. No impact on the τ-phosphorylation sites Ser-202, Thr231/Ser235, Ser262 and Ser396/Ser404 was found. The total number of homomeric α7-nicotinic receptors (α7-nAChRs) and their affinity for [125I]α-bungarotoxin remained unaltered. Upon incubation with the putatively protective tetrapeptide propionyl–isoleucine–isoleucine–glycine–leucine (Pr-IIGL), an analogue of the region [31–34] of Aβ, cell bodies were swollen in the region of the apical dendrite. These morphological alterations, different from those elicited by Aβ1−42, did not involve MAP2 expression changes. In contrast to Aβ1−42, Pr-IIGL caused a massive hyperphosphorylation of the τ-protein at Ser-202 and at Ser396/Ser404. The total number of homomeric α7-nAChRs and their affinity for [125I]α-bungarotoxin were unaffected. In conclusion, the present results show a toxic effect of Aβ1−42 on the cytoskeletal structure at concentrations normally present in the brains of Alzheimer's disease patients, but raise some doubts about the role of Aβ1−42 fibrils as a direct trigger of τ-hyperphosphorylation. The tetrapeptide Pr-IIGL cannot be considered protective with regard to cell morphology. Although it prevents the Aβ1−42-induced retraction of dendrites, it exhibits other toxic properties. The homomeric α7-nAChRs were not affected either by Aβ1−42 incubation or by Pr-IIGL-induced τ-hyperphosphorylation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1460-9568.2005.03909.x
Permalink
