Effects of polygonatum sibiricum polysaccharide on learning and memory in a scopolamine-induced mouse model of dementia

R74; BACKGROUND: Learning and memory processes are accompanied by complex neuropathological and biochemical changes. Free radicals play an important role in learning and memory damage. OBJECTIVE: To observe the effects of polygonatum sibiricum polysaccharide (PSP) in comparison with vitamin E on inhibiting free radical damage, as well as improving the degree of cerebral ischemia and learning and memory in a scopolamine-induced mouse model of dementia.DESIGN: Randomized controlled animal study.SETTINGS: Department of Pharmacology, Taishan Medical College; Shandong Jewim Pharmaceutical Co., Ltd.MATERIALS: A total of 105 healthy Kunming mice, comprising 90 males and 15 females that were clean grade, were provided by the Animal Center of Taishan Medical College. PSP (extracted and purified by Huangjing, Taishan) was provided by the Department of Traditional Chinese Medicine, Taishan Medical College (purity of 79.6% by using a phenol-concentrated sulphate acid method), and hydrogen bromine acid scopolamine injection solution (SCO) by Shanghai Hefeng Pharmaceutical Co., Ltd.METHODS: This study was performed at the Pharmacological Laboratory of Taishan Medical College from March to June 2007. ① A total of 75 healthy Kunming male mice of clean grade were randomly divided into a normal control group, positive control group, and low-dosage and high-dosage PSP groups, with 15 mice in each group. Mice in both the low-dosage and high-dosage PSP groups were intragastrically administered 0.5 g/kg and 2.0 g/kg PSP, respectively. Mice in the positive control group were intragastrically administered 0.5 g/kg vitamin E. In addition, mice in both the normal control group and model group were intragastrically administered the same volume of saline, respectively, once a day for 7 consecutive days. One hour after the final administration on day 6, mice in the positive control group, model group, low-dosage and high-dosage PSP groups were subcutaneously injected with 3.0 mg/kg SCO, while mice in the normal control group were subcutaneously injected with the same volume of distilled water. Ten minutes later, the step test was employed to measure memory. The training was performed 5 times, with 30-minute intervals between 2 sets. If the mice remained on the platform (latent period) for 30 minutes, they were determined to have learned the task. An eligible percentage was then recorded. Twenty-four hours later, the number of error responses from each mouse was recorded in a 5-minute