银杏叶提取物对血管性痴呆大鼠海马胆碱能纤维的影响

背景银杏叶提取物对血管性痴呆(vasculardementia,VD)大鼠的记忆功能及海马胆碱能纤维的影响,是目前国内外研究的热点,具有重大理论意义.目的研究银杏叶提取物对VD的治疗作用及其机制.设计随机对照实验研究.地点和对象实验在华中科技大学同济医学院神经生物学教研室完成.实验动物采用纯种雄性Wistar大白鼠49只,体质量220～280g(华中科技大学实验动物中心供给).干预成年Wistar雄性大鼠49只随机分为假手术组(n=9)、VD模型组(n=40).用避暗试验测定假手术组和VD模型组手术7d后的学习、记忆功能.将出现明显学习、记忆功能障碍的36只VD模型大鼠随机分为4组模型对照组及银杏叶提取物低、中、高剂量组,每组9只动物,各组分别给予生理盐水1mL/100g、银杏叶提取物100,150,200 mg/kg灌胃10 d后,再用明、暗箱装置测定各组大鼠的学习、记忆功能.用胆碱酯酶染色观察了各组大鼠海马胆碱能纤维的密度.主要观察指标①GBE对VD大鼠避暗试验的影响.②CA1区胆碱能纤维染色的结果.结果与假手术组比较,模型组大鼠学习训练中错误次数明显增多,遭受电击的累积刺激时间(cumulatedstimulation time,CST)明显延长;记忆测试中小鼠从放入明室到进入暗室遭受电击的步入潜伏期(stepthrough latency,STL)明显缩短,错误次数明显增多,CST明显延长(P＜0.01).与模型对照组比较,银杏叶提取物中、高剂量组学习训练中小鼠首次遭受电击后从暗室逃入明室的逃避潜伏期(escapelatency,EL)明显缩短,银杏叶提取物低、中、高剂量组错误次数明显减少(P＜0.01);记忆测验中银杏叶提取物低、中、高剂量组STL明显延长,EL明显缩短,CST明显缩短,错误次数明显减少.在光镜下可以观察到模型组与假手术对照组比较大鼠海马CA1区胆碱能纤维密度明显稀疏,吸光度明显降低(P＜0.01).银杏叶提取物低、中、高剂量治疗组与模型对照组比较大鼠海马CA1区胆碱能纤维密度明显变密,吸光度明显升高(P＜0.01),表明GBE可以增加VD大鼠海马CA1区乙酰胆碱的含量.结论GBE对VD大鼠有显著的治疗作用,其机制可能与增加海马胆碱能纤维的密度有关.

Effect of ginkgo biloba extract on cholinergic fibers in the hippocampus in rats of vascular dementia

BACKGROUND: Ginkgo biloba extract(GBE) affects memory and cholinergic fibers in the hippocampus in VD rats, which is a hot topic of research at home and abroad at present and provides an important theoretical significance.OBJECTIVE: To study the therapeutic effect and its mechanism of GBE on vascular dementia.DESIGN: A randomized, controlled trial design.SETTING and MATERIALS: Research was completed at Neurobiology Department of Tongji Medical College, Huazhong University of Science and Technology. Male Wistar rats weighing 220- 280 g obtained from experimental animal center of Huazhong University of Science and Technology were employed.INTERVENTION: Forty-nine male Wistar rats were divided into two groups: sham-operation group ( n = 9) and VD model groups ( n = 40). Seven days after operation, the rats were tested for learning and memory ability by passive avoidance conditioned response. Thirty-six VD model rats which were unable to acquire the passive avoidance response were divided into four group randomly: model control group, GBE low dosage group, GBE moderate dosage group, GBE high dosage group, 9 rats for each group. The physiological saline 1 mL/100 g, GBE of 100, 150 and 200 mg/kg were applied in each group respectively by gastric infusion for 10 days. After which, the learning and memory ability of rats in every group were determined by the illuminated and dark chambers; and the density of hippocampal cholinergic fibers tissues in rats in all groups were observed by acetylcholinesterase staining.CA1 region.RESULTS: Compared with sham-operation group, in model group, during the learning test, the mistakes were remarkably increased and the cumulated stimulation time(CST) of electric shock were remarkably prolonged; During the memory test, the step through latency(STL) was remarkably shortened for the rats being shocked by electricity from an illuminated chamber to the dark chamber, the mistakes increased remarkably and CST remarkably prolonged ( P ＜ 0.01 ). Compared with model control group, in GBE moderate and high dosage groups, during the learning test, the escape latency(EL) for the rats escaping from the dark chamber to the illuminated one after the first electric shock was remarkably shortened and the mistakes in GBE low, moderate and high dosage groups remarkably reduced(P ＜ 0.01); During the memory test, in GBE low, moderate and high dosage groups, STL was remarkably prolonged, EL and CST shortened and the mistakes reduced. Under the fiberscope, it was observed that the density of cholinergic fibers in the hippocampus CA1 region was remarkably sparse and the absorbance decreased ( P ＜ 0.01) in the model group, compared with the shain-operated groups.The density of cholinergic fibers in the hippocampus CA1 region was remarkably dense and the absorbance was increased( P ＜ 0. 01 ) in GBE low,moderate and high dosage group, compared with the model group, indicating that GBE may increase the content of cholinergic fibers in the hippocampus CA1 region in VD rats.CONCLUSION: GBE achieves significant therapeutic effect on VD in rats and its mechanism is probably related to the improvement of the density of cholinargic fibers in the hippocampus.