Title

Nature of the Neurotoxic Membrane Actions of Amyloid-β on Hippocampal Neurons in Alzheimer's Disease

Document Type

Article

Language

eng

Format of Original

10 p.

Publication Date

3-2014

Publisher

Elsevier

Source Publication

Neurobiology of Aging

Source ISSN

0197-4580

Original Item ID

doi: 10.1016/j.neurobiolaging.2013.08.035

Abstract

The mechanism by which amyloid-β (Aβ) produces brain dysfunction in patients with Alzheimer's disease is largely unknown. According to previous studies, Aβ might share perforating properties with gramicidin, a well-accepted membrane-disrupting peptide. Therefore, we hypothesize that the key steps leading to synaptotoxicity by Aβ and gramicidin involve peptide aggregation, pore formation, and calcium dysregulation. Here, we show that Aβ and gramicidin form aggregates enriched in β-sheet structures using electron microscopy, and Thioflavin and Congo Red staining techniques. Also, we found that Aβ and gramicidin display fairly similar actions in hippocampal cell membranes, i.e. inducing Ca2+ entry and synaptoxicity characterized by the loss of synaptic proteins and a decrease in neuronal viability. These effects were not observed in a Ca2+ free solution, indicating that both Aβ and gramicidin induce neurotoxicity by a Ca2+-dependent mechanism. Using combined perforated patch clamp and imaging recordings, we found that only Aβ produced a perforation that progressed from a small (Cl-selective pore) to a larger perforation that allowed the entry of fluorescent molecules. Therefore, based on these results, we propose that the perforation at the plasma membrane by Aβ is a dynamic process that is critical in producing neurotoxicity similar to that found in the brains of AD patients.

Comments

Neurobiology of Aging, Vol. 35, No. 3 (March 2014): 472-481. DOI.