苯乙醇苷纳米乳经鼻给药的脑内递药特性及抗AD药效学研究

Alzheimer's disease (AD) as the most common type of senile dementia, has shown a remarkable increase incidence of the morbidity in recent years with enormous hazard. Currently, there is still a lack of adequate treatment for the AD with resultful medications, therefore discovering new medicines from natural products has become inevitable. Drugs cannot efficiently cross the blood-brain barrier (BBB) towards the targeted area of the brain, which is a crucial bottleneck restricting the treatment of AD. An unique relationship exists between nasal cavity and brain in the anatomical, physiological structure, rendering nasal administration a possible solution that drugs effectively bypass the BBB and selectively locate in the targeted area of the brain. Nanoemulsion is a hotspot research formulation development for drug brain targeting by nasal administration. Cistanches as classics traditional Chinese medicine for curing amnesia and anti-ageing, the anti-AD effect of its main active ingredient phenylethanoid glycosides (PhG) has been widely confirmed. Comprehensive existing research and preliminary work basis of our research group, this project intended to use nanoemulsion as the drug delivery system through the nasal administration route to study the pharmacokinetics and brain-targeting delivery characteristics of PhG. APP/PS1 double transgenic mice model was employed to compare the influence of PhG through the nasal administration route and oral administration route on the anti-AD effect. Through this project research, we intend to clarify the delivery rules of PhG in the nose-brain pathways and to evaluate the efficacy. Providing theoretical support for the R&D of new drugs and potential route development of AD treatment with PhG as the mother nucleus structure, and enriching the theory and practice of traditional Chinese medicine for nasal administration.

AD为老年痴呆最常见类型，近年来发病率显著上升，危害严重。目前尚缺乏AD有效治疗手段，从天然产物中发掘新药已成必然。药物无法有效跨越血脑屏障到达脑部靶区，是制约AD治疗的重要瓶颈。鼻腔在解剖生理结构上与脑部存在着独特联系，经鼻给药可使药物有效绕过血脑屏障，选择性定位于脑部靶区。纳米乳是经鼻给药发挥药物脑靶向性的热点研究剂型。肉苁蓉作为治疗健忘、抗老防衰的经典中药，其主要有效成分苯乙醇苷的抗AD作用已被广泛证实。综合已有研究和课题组前期工作基础，本项目拟以纳米乳为载药系统研究肉苁蓉苯乙醇苷经鼻给药的药动学和脑内递药分布规律，并借助APP/PS1双转基因小鼠模型对其鼻腔给药和口服给药的抗AD作用进行药效学比较。通过本项目研究，力图阐明肉苁蓉苯乙醇苷在鼻-脑通路中的递药规律，并评价药效，为研发以苯乙醇苷为母核结构的AD治疗新药、新型给药系统提供理论支撑，丰富中药和天然药物鼻腔给药的理论和实践。

本项目围绕苯乙醇苷纳米乳经鼻给药防治阿尔茨海默病这一科学问题，通过鼻腔给药途径，采用药理学、毒理学、药代动力学、分子生物学等技术手段，开展肉苁蓉苯乙醇苷抗AD作用的脑靶向性研究。综合系统文献调研和课题组前期研究基础，不断优化完善研究方案，在项目实施的4年期间，按照原定计划：（1）通过急性毒性实验和鼻粘膜毒性实验，以小鼠行为体征变化、重要组织的脏器系数及HE图谱等为考察指标，证明了苯乙醇苷纳米乳经鼻给药的安全性，为后续开展苯乙醇苷纳米乳鼻腔给药抗AD作用研究提供科学依据。（2）在对肉苁蓉苯乙醇苷纳米乳鼻腔给药的安全性进行系统评价的基础上，采用经典的大鼠在体鼻腔循环灌流模型，以毛蕊花糖苷和松果菊苷为分析指标，利用HPLC法测定其在循环药液中含量，采用体积校正法计算各循环液的吸收速度常数，考察并分析在体状态下两种剂型的苯乙醇苷制剂的经鼻吸收特性；并考察了制剂pH值与吸收促进剂氮酮对苯乙醇苷纳米乳鼻腔吸收的影响，得出苯乙醇苷纳米制剂经鼻吸收的最佳pH值和氮酮比例，为后续进行苯乙醇苷纳米乳经鼻给药抗AD药效学研究奠定基础。（3）借助APP/PS1双转基因AD模型小鼠，利用筑巢实验、Morris水迷宫实验、跳台及Y迷宫实验等一系列的行为学研究来考察苯乙醇苷纳米乳经鼻给药的抗AD作用，证明苯乙醇苷纳米乳能显著改善模型小鼠的学习记忆能力及空间辨别能力，与口服给药相比，鼻腔给药能更好的发挥作用，为后续苯乙醇苷纳米乳的体内代谢及脑靶向性研究提供了参考。（4）通过开展肉苁蓉苯乙醇苷纳米乳经鼻给药与口服给药的药代动力学对比研究，综合药效学研究结果，发现相较于口服给药，肉苁蓉苯乙醇苷经鼻给药更易跨过血脑屏障，到达脑部区域发挥作用；另一方面明确了肉苁蓉苯乙醇苷在鼻-脑通路中发挥一定的脑靶向性作用，并揭示了其在脑内的分布、转运规律。综上所述，本项目首次将经鼻给药途径引入到肉苁蓉苯乙醇苷抗AD作用的研究，探讨药物经鼻腔入脑后的靶向性，为研制以苯乙醇苷为母核结构的新型AD治疗新药、新制剂提供理论支撑。