Alzheimer's disease: halothane induces Abeta peptide to oligomeric form--solution NMR studies.

Alzheimer's disease (AD) is a significant contributor to cognitive decline and is responsible for about half of the cases of dementia in later life. Although exact etiology of AD is not known, however, many risk factors for AD are identified. Anesthesia for elderly patients is considered as a risk factor in AD as they frequently experience deterioration in cognitive function with long exposure to anesthetics during surgery. Inhaled anesthetic agents remain the mainstay for patients undergoing major surgical operations. This study using multidimensional NMR spectroscopy provides the first direct evidence in vitro that inhaled anesthetic, halothane specifically interacts with Abeta40 and Abeta42 peptide. Halothane induces structural alternation of Abeta peptide from soluble monomeric alpha-helical form to oligomeric beta-sheet conformation, which may hasten the onset of AD. Abeta42 is more prone to oligomerization compared to Abeta40 in the presence of halothane. The molecular mechanism of halothane induced structural alternation of Abeta peptide is discussed.