Amyloid Beta: Multiple Mechanisms of Toxicity and Only Some Protective Effects?

Abstract

Amyloid beta (Aβ) is a peptide of 39–43 amino acids found in large amounts and forming deposits in the brain tissue of patients with Alzheimer’s disease (AD). For this reason, it has been implicated in the pathophysiology of damage observed in this type of dementia. However, the role of Aβin the pathophysiology of AD is not yet precisely understood. Aβhas been experimentally shown to have a wide range of toxic mechanismsin vivoandin vitro, such as excitotoxicity, mitochondrial alterations, synaptic dysfunction, altered calcium homeostasis, oxidative stress, and so forth. In contrast, Aβhas also shown some interesting neuroprotective and physiological properties under certain experimental conditions, suggesting that both physiological and pathological roles of Aβmay depend on several factors. In this paper, we reviewed both toxic and protective mechanisms of Aβto further explore what their potential roles could be in the pathophysiology of AD. The complete understanding of such apparently opposed effects will also be an important guide for the therapeutic efforts coming in the future.