title: Hormesis and amyloid-β protein: physiology or pathology?
abstract: Hormesis is the concept that low doses of a toxin can have beneficial effects while high doses are harmful. This is also known as the inverted-U shaped dose-response curve. Hormesis appears to be a universal law for the function of memory mimetics. Amyloid-β protein is widely recognized to be a toxic agent responsible for plaque formation in Alzheimer's disease. In high doses it also produces amnesia. In lower, physiological doses, it enhances long term potentiation and memory. Blocking amyloid-β protein in animals without overproduction of the protein results in amnesia. At low doses, amyloid-β also increases neurite outgrowth, produces presynaptic enhancement, and may quench oxidative damage. It is postulated that both over- and underproduction of amyloid-β can lead to memory deficits. This is similar to a number of hormonal diseases, e.g., thyroid, where both low and high levels produce disease.
authors.affiliation: Division of Geriatric Medicine, Saint Louis University School of Medicine, St. Louis, MO, USA. morley@slu.edu
authors.forename: John E
authors.initials: JE
authors.lastname: Morley
authors.forename: Susan A
authors.initials: SA
authors.lastname: Farr
mesh_terms: D000544:Alzheimer Disease / Q000150:complications / Q000378:metabolism / Q000473:pathology; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D000818:Animals; D004195:Disease Models, Animal; D059165:Hormesis / Q000502:physiology*; D006801:Humans; D008569:Memory Disorders / Q000209:etiology*
chemical_list: D016229:Amyloid beta-Peptides