地黄对阿尔茨海默病小鼠行为学的影响及其对血脑屏障的保护作用

Effects of Radix Rehmanniae on behavior and blood-brain barrier in Alzheimer's disease mice

目的:探讨中药地黄对阿尔茨海默病模型小鼠日常活动能力和恐惧记忆能力的行为学影响及其对血脑屏障的保护作用。方法:38只4月龄APP/PS1双转基因小鼠随机分为模型对照组(给予等渗氯化钠溶液)、地黄小剂量组(给予地黄5g·kg^(-1)·d^(-1))和地黄大剂量组(给予地黄12g·kg^(-1)·d^(-1)),连续灌胃给药3个月,每日给药1次。分别采用筑巢实验和条件恐惧实验检测小鼠日常活动能力和恐惧记忆能力;硫黄素T染色检测小鼠皮层和海马CA1区β淀粉样蛋白(Aβ)沉积;免疫荧光双重标记染色检测小鼠皮层和海马CA1区血管内皮完整性及血脑屏障渗出情况。结果:与模型对照组比较,地黄小、大剂量组日常活动能力均明显改善(均P<0.01);地黄大剂量组恐惧记忆能力明显提高(P<0.01);地黄大剂量组皮层和海马CA1区Aβ沉积量明显减少,面积占比明显减小,地黄小剂量组海马CA1区Aβ沉积面积占比也减小(均P<0.05);地黄小、大剂量组大脑皮层CD34阳性面积占比显著增加,纤维蛋白原阳性面积占比显著减小(均P<0.05);地黄大剂量组海马CA1区CD34阳性面积占比显著增加,纤维蛋白原阳性面积占比显著减小(均P<0.05)。结论:中药地黄可以提高模型小鼠的日常活动能力及恐惧记忆功能,减少脑内Aβ沉积,且大剂量时效果更为显著;其机制可能与降低血脑屏障通透性、保护血脑屏障完整性有关。

Objective: To investigate the effects of Radix Rehmanniaeon behavior and blood brain barrier(BBB) in Alzheimer’s disease mice.Methods: Thirty-eight4-month-old APP/PS1 double transgenic mice were randomly divided into three groups:model group,Radix Rehmanniaelow-dose group andRadix Rehmanniaehigh-dose group.Saline,Radix Rehmanniae 5g·kg^(-1)·d^(-1) andRadix Rehmanniae 12g·kg^(-1)·d^(-1)were given to each group by continuous gavage once a day for three months, respectively. The changes in activities of daily live and fear conditioning memory behavior of mice were examined by nesting behavior test and fear conditioning test, respectively. Theβ-amyloid protein(Aβ)depositions in cortex and hippocampal CA1 area of mice were detected by thioflavin T staining. The CD34 and activities fibrinogen(Fib) immunofluorescence double staining were used to determine the vascular endothelial integrity and BBB exudation.Results:Compared with model mice, activities of daily live were significantly improved inRadix Rehmanniaelow-dose and high-dose groups(bothP<0.01), the fear memory ability was significantly increased inRadix Rehmanniaehigh-dose group(P<0.01). The amount of Aβdeposition in cortex and hippocampal CA1 decreased significantly inRadix Rehmanniae high-dose group, the area ratio decreased significantly;the area ratio of Aβdeposition in hippocampal CA1 region inRadix Rehmanniaelow-dose group also decreased(all P<0.05). The proportions of CD34 positive area of cortex in low and high doseRadix Rehmanniaegroups increased, the percentage of fibrinogen positive area decreased(all P<0.05). The proportion of CD34 positive area in hippocampal CA1 region inRadix Rehmanniaehigh-dose group was significantly increased, the percentage of fibrinogen positive area decreased significantly(bothP<0.05).Conclusions:Radix Rehmanniae,especially high-dose can improve the activities of daily live and fear conditioning memory function of APP/PS1 mice, reduce the deposition of Aβin brain. The mechanism may be related to the reduction of BBB permeability and the protection of the integrity of BBB.