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

Amyloid β protein (Aβ) 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 Thunb water extract (PWE) on Aβ25-35-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 Aβ25-35 (10 μg/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 Aβ25-35. The Aβ25-35 treatment accelerated the lipid peroxidation, and PWE attenuated the Aβ-induced increase in brain 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 Aβ-injected group. These findings suggest that PWE exerts a preventive effect against cognitive deficits induced by Aβ25-35 accumulation in Alzheimer's disease, and that this effect is mediated by the antioxidant properties of PWE.