Protective effect of Polygonum multiflorum Thunb on amyloid β-peptide 25-35 induced cognitive deficits in mice

Amyloid beta protein (A beta) may be neurotoxic during the progression of Alzheimer's disease by eliciting oxidative stress. This study was designed to determine the effect of Polygonum multiflorum Thumb water extract (PWE) on A beta 25-35-induced cognitive deficits and oxidative stress in mice. Mice were fed experimental diets comprising either 0.5 or 1% PWE for 4 weeks, and then received a single intracerebroventricular (i.c.v.) injection of A beta 25-35 (10 mu g/mouse). Behavioral changes in the mice were evaluated using passive avoidance and water-maze tests. The consumption of PWE significantly ameliorated the cognitive deficits caused by i.c.v. injection of A beta 25-35. The A beta 25-35 treatment accelerated the lipid peroxidation, and PWE attenuated the A beta-induced increase in levels of thiobarbituric acid reactive substances. There was an increase in glutathione peroxidase activity in PWE-treated groups. The acetylcholinesterase activity in the brain and serum was lower in PWE supplemented groups than in the only A beta-injected group. These findings suggest that PWE exerts a preventive effect against cognitive deficits induced by A beta 25-35 accumulation in Alzheimer's disease, and that this effect is mediated by the antioxidant properties of PWE. (c) 2005 Elsevier Ireland Ltd. All rights reserved.