Ameliorative effects of physcion 8-O-β-glucopyranoside isolated from Polygonum cuspidatum on learning and memory in dementia rats induced by Aβ1-40

Context: Polygonum cuspidatum Sieb. Et Zucc. (Polygonaceae) has been traditionally used in folk medicine to treat various diseases. Objective: This study investigates the ameliorative effects of physcion 8-O-beta-glucopyranoside (PSG) isolated from P. cuspidatum on learning and memory in dementia rats induced by A beta(1-40). Materials and methods: Dementia rats were prepared by intracerebroventricular injection of A beta(1-40). PSG (5, 10, 20, and 40 mg/kg/d, for 5 d) was administered orally. Ameliorative activity of PSG in dementia rats was evaluated by the Morris water maze (MWM) test, and its mechanisms were explored by evaluating AchE activity, levels of DA, NE, and 5-HT in hippocampus, and drebrin protein expressions in hippocampus. Results: Our results indicated that PSG (5, 10, 20, and 40 mg/kg/d) significantly inhibited the prolonged latency in dementia rats (p<0.05), and inhibitory rates were 16.5, 22.7, 33.0, and 44.8% after 5 d of learning, indicating that PSG improves learning and memory of dementia rats. Furthermore, PSG significantly decreased AchE activity (10, 20, and 40 mg/kg/d; p<0.05), increased 5-HT (20 and 40 mg/kg/d, p<0.05), NE (10, 20, and 40 mg/kg/d; p<0.05), and DA levels (5, 10, 20, and 40 mg/kg; p<0.05) in the hippocampus. Additionally, PSG obviously decreased the A beta contents in hippocampus (10, 20, and 40 mg/kg/d; p<0.05), and upregulated drebrin protein expressions (5, 10, 20, and 40 mg/kg/d; p<0.05). Conclusions: PSG can significantly enhance learning and memory in A beta(1-40)-induced dementia rats, and the mechanisms may be related to increase levels of Ach, 5-HT, NE, and DA, decrease A beta contents, and up-regulation of drebrin proteins in hippocampus.