Abstract

Objective : This study was designed to examine the effects of orally administered Prunus persica water extract (PPE), which is used as herbal medicine, for treatment of Yu Xue (stasis of blood) and tacrine on the basal concentration of extracellular acetylcholine in the hippocampus of rats. Methods : To investigate the effects of PPE and tacrine on concentration of extracellular acetylcholine in the hippocampus of rats, the microdialysis technique, under the same experimental conditions, was used. And we used male Wistar rats which were 7 weeks of age and 210-290 g. PPE was extracted with boiling water, and the rats were anesthetized with pentobarbital Na. Their skulls were exposed and a hole was drilled for implantation of a microdialysis probe. In order to increase the recovery of acetylcholine, a probe with a long membrane was used. One day after surgery, the microdialysis probe was perfused with Ringer's solution at a flow rate of 1.5 l/min. The acetylcholine concentration in dialysis samples was measured by high-performance liquid chromatography (HPLC) with electrochemical detection. AChE activity was measured using the radiometric method, as described by Sherman. Results : The comparative effects of PPE and tacrine on hippocampal extracellular acetylcholine concentration was that these cholinesterase inhibitors produced dose-dependent increases in the extracellular acetylcholine concentration. And the effect of PPE and tacrine on rat brain AChE activity was that PPE produced maximal inhibition at 1 h after administration, when AChE activity was 44% of the intact level. AChE activity gradually recovered thereafter, and reached 78% of the intact level at 12 h after administration. Conclusion : In this study, PPE has a potent activity and a long-lasting effect on the central cholinergic system, in terms of the basal concentration of extracellular acetylcholine in the hippocampus and the AChE activity in the brain of rats. And oral administration of PPE increased dose-dependently the basal concentration of extracellular acetylcholine in the hippocampus of rats. PPE may be one of the more useful cholinesterase inhibitors for the treatment of Alzheimer's disease.