葛根素对淀粉样β蛋白所致痴呆模型小鼠学习记忆的影响

背景葛根素是中药葛根的主要有效成分,能对抗东莨菪碱、D-半乳糖等因素引起的动物学习记忆障碍.目的探讨葛根素对淀粉样β蛋白所致痴呆模型小鼠学习记忆障碍的保护作用及脑和血中超氧化物歧化酶活性、丙二醛含量的变化.设计随机对照实验.单位首都医科大学药理学系.材料实验于2002-03/06在首都医科大学药理学系完成.实验选用40只ICR小鼠,随机分成4组假手术组、痴呆模型组、葛根素25 mg/kg组、葛根素50 mg/kg组,每组10只.方法①造模小鼠戊巴比妥钠麻醉,痴呆模型组、葛根素25 mg/kg组、葛根素50 mg/kg无菌操作下一次性右侧脑室内注射淀粉样β蛋白3μL/只.假手术组操作同模型组,但不注射淀粉样β蛋白.②给药假手术组、模型组腹腔注射生理盐水10mL/kg;葛根素25 mg/kg组腹腔注射25 mg/kg;葛根素50mg/kg组腹腔注射50mg/kg.各组于造模当日开始给药,12 d后开始行为学检测.③用Morris水迷宫法检测小鼠学习记忆能力,记录2 min内寻找到平台的时间(逃避潜伏期),航行距离,初始角度及搜索策略,作为学习成绩.④小鼠完成上述实验后,乙醚麻醉眼眶取血,制备血清,然后断头处死,迅速取右脑冰浴下制备脑匀浆,检测脑、血清中超氧化物歧化酶活性、丙二醛含量.主要观察指标①各组小鼠到达平台的逃避潜伏期和游泳距离、搜索策略及初始角度.②各组小鼠脑、血清中超氧化物歧化酶活性、丙二醛含量.结果40只小鼠均进入结果分析.①葛根素25 mg/kg和50 mg/kg组逃避潜伏期、航行距离缩短(P＜0.05～0.01).搜索策略及初始角度结果显示随着训练天数的增加,各组小鼠随机+边缘式策略的出现率逐渐下降;其中假手术组及葛根素25 mg/kg组、葛根素50 mg/kg组的下降速度和程度较痴呆模型组快,同时趋向+直接式的增加速度和程度也较痴呆模型组快.初始角度各组间均无显著差异(P＞0.05).②葛根素25 mg/kg组、葛根素50 mg/kg组能使模型小鼠脑及血中超氧化物歧化酶增多、丙二醛的减少(P＜0.05～0.01).结论葛根素可对抗淀粉样β蛋白的神经毒性,使模型小鼠的学习记忆成绩提高,与剂量无关,可能与清除脑自由基及提高抗氧化活性作用有关.

Effects of puerarin on learning and memory of model mouse with beta amyloid peptide-induced dementia

BACKGROUND: Puerarin, the main effective component of Chinese herb, Radix puerariae, is isoflavone monomer, which can counteract learning and memory impairment induced by scopolamine or D-galactose etc.OBJECTIVE: To investigate the protective effects of puerarin on β-amYloid peptide-induced learning and memory impairment of model mouse of dementia and the changes of superoxide dismutase activity and malondialdhehyde content in brain and blood.DESIGN: Randomized controlled trailSETTING: Department of Pharmacology, Capital University of MedicalSciencesMATERIALS: The experiment was conducted in Departmentof Pharmacology of Capital University of Medical Sciences from March to June 2002.A total of 40 ICR mice were selected and randomly divided into 4 groups:pseudooperation group, dementia model group, puerarin 25 mg/kg group and puerarin 50 mg/kg group, with 10 in each group.METHODS: ①Model preparation: After anaesthesia with pentobarbital sodium, single intraventricular injection of 3 μL β-amyloid peptide was conducted from right side on each mouse in dementia model group, puerarin 25 mg/kg group and puerarin 50 mg/kg group under aseptic manipulation. The same operation was carried out on the mouse in pseudooperation group but without injection of β-amyloid peptide. ②Giving medicine:10 mL/kg physiological saline was intraperitoneally injected into the mouse in pseudooperation group and model group; 25 mL/kg puerarin was intraperitoneally injected to the mouse in 25 mg/kg puerarin group; 50 mL/kg puerarin was intraperitoneally injected to the mouse in 50 mg/kg puerarin group.The medicines were given to each group from the day of model preparation on and behavioral test was carried out 12 days later. ③ Morris water maze examination was used to detect learning and memory ability of the mice.Time for finding the platform (escape latency) in 2 minutes, swimming distance, original angle and search strategy were recorded as learning results.④When the above experiment was finished, anaesthesia with ether was applied to the mice and blood was collected from the orbit to prepare serum.After that, the mice were put to death by decapitation and the tissue of right-brain of the mice were rapidly took out to prepare cerebral homogenate in ice bath, then superoxide dismutase activity and malondialdhehyde content were determined in brain and serum.MAIN OUTCOME MEASURES: ①Escape latency, swimming distance,search strategy and original angle for the mouse in each group to reach the latform. ②Superoxide dismutase activity and malondialdhehyde content in brain and blood of the mouse in each group.RESULTS: All the 40 mice were involved in result analysis. ① Escape latency and swimming distance were shortened in puerarin 25 mg/kg and 50 mg/kg groups (P ＜ 0.05-0.01). The results of search strategy and original angle indicated that as the number of training days increased, the frequency of randomization+magin strategy gradually decreased; The decreasing rates and extents in pseudooperation group and puerarin 25 mg/kg and 50 mg/kg puerarin were more rapid than that in dementia model group,meanwhile, the increasing rates and extents of frequency of tendency+directness strategy in these groups were more rapid than that in dementia model group. There was no significant difference in original angle between groups (P ＞ 0.05). ② The content of superoxide dismutase increased and that of malondialdhehyde decreased in brain and blood of the model mouse in puerarin 25 mg/kg group andpuerarin 50mg/kg group (P ＜ 0.05 -0.01).CONCLUSION: Puerarin can counteract the neurotoxicity of β-amyloid peptide, which improves learning and memory of model mouse. It is not relevant to the dosage but probably related with elimination of cerebral free radical and improvement of antioxidation activity.