【作者】 李丹清；

【导师】 安利佳；

【作者基本信息】 大连理工大学 ， 生物化工， 2005， 博士

【摘要】 本研究旨在探讨梓醇在沙土鼠脑缺血再灌注模型中的体内作用及机制。 应用无损伤动脉夹短暂夹闭沙土鼠两侧颈总动脉,建立脑缺血再灌注模型,通过行为学、组织形态学评价模型及梓醇在该模型中的作用。5分钟持续性脑缺血导致海马CA1区锥体神经元结构蛋白MAP-2消失,神经元大量死亡,脑梗死广泛形成和动物学习、记忆能力下降。 梓醇短期应用(连续腹腔注射4天)能明显减轻上述脑缺血再灌注造成的损伤,即能有效减少MAP-2破坏和神经元死亡,降低脑梗死,改善缺血动物学习记忆功能,但不能改善无脑缺血损伤沙土鼠的认知水平,表现为神经保护作用。梓醇神经保护作用的疗效远期与近期相同,对药用剂量和药用时间呈现依赖性。1mg/kg梓醇已显示出明显的保护作用,随着剂量的增加,其保护作用增强。在5mg/kg和10mg/kg梓醇组,海马CA1区存活神经元数量比正常对照动物还多。再灌注后3小时之内应用梓醇,神经保护作用显著,随着给药时间的延迟,神经保护作用减弱,再灌注后6小时开始应用,存活神经元数量减少,动物学习记忆能力得不到改善。说明梓醇神经保护作用的有效给药时间范围(有效时间窗)应在再灌注后3小时之内。 梓醇长期应用(连续腹腔注射10天—14天)既能显著改善无脑缺血损伤而认知能力低下沙土鼠的认知水平,也能显著改善上述那些受缺血损伤并于再灌注后6小时才开始用药的沙土鼠的认知能力。提示梓醇在不同的应用疗程下具有不同的神经药理作用,即短期应用以神经保护作用为主,长期应用则可能以神经营养作用为主。 借助于流式细胞仪、电子显微镜、免疫组化技术、原位细胞死亡检测技术和紫外分光光度仪进一步探讨了梓醇神经保护作用的体内机制。脑缺血再灌注后,脑内GSH-Px酶活性显著降低,iNOS酶活性明显增强,Bax蛋白表达和凋亡细胞数量均明显增加。梓醇可显著提高GSH-Px酶活力,促进Bcl-2蛋白表达,抑制iNOS酶活性和Bax蛋白更多还原

【Abstract】 The purpose of this study mainly aims at observation the effects of catalpol and its action mechanism in gerbil global cerebral ischemia-reperfusion model.Global cerebral ischemia is induced by transient bilateral occlusion of the common carotid arteries with non-traumatic micro aneurysm clips. Histological and morphologic as well as behavioral analysis is used to evaluate the model and the effects of catalpol. 5-min ischemia induces the disappearance of microtubule associated protein-2 in hippocampal CA1 neurons and the death of large number neurons as well as the formation of broad brain infarct and the damage of cognitive ability of gerbils.Catalpol used in short term (consecutively intra-peritoneal injection 4 days) mitigates the damage induced by ischemia-reperfusion and presents neuroprotection in the situation in which catalpol is given within 3h after reperfusion. Catalpol at the dose of 1mg/kg can significantly rescue neurons in hippocampal CA1 subfield and reduce cognitive impairment. The neuroprotective efficacy of catalpol becomes more evident at the doses of 5mg/kg and 10mg/kg. Of great importance is the finding that the neuroprotective efficacy of catalpol still can be seen even when the observational period is lasted out 35 days after ischemia. Although catalpol can also protect against neuronal death when the treatment is delayed up to 6 h after reperfusion, it can not ameliorate the animal cognitive ability. So we conclude that therapeutic time-window for catalpol in gerbil global cerebral ischemia model should be limited within 3 h after ischemia.Catalpol given in long term (consecutively intra-peritoneal injection 10-14 days) can not only obviously ameliorate the learning and memory ability in gerbils whose cognitive ability are innate weak, but also markedly improve the cognition of gerbils subjected to brain ischemia even in the situation in which catalpol is used up to 6h after reperfusion. All these suggest that catalpol may be of different pharmacological activity in different condition, namely, trophic function may be primary in long term using, on the contrary, neuroprotection is predominant.The neuroprotective mechanism of catalpol is further studied in vivo using electron更多还原