淫羊藿激活CREB/BDNF信号通路改善APP/PS1双转基因小鼠的认知功能

Epimedium activates CREB/BDNF signaling pathway to improve cognitive function in APP/PS1 double transgenic mice

目的研究淫羊藿能否通过调节环磷酸腺苷效应元件结合蛋白(cAMP response element binding protein,CREB)/脑源性神经营养因子(brain-derived neurotrophic factor,BDNF)信号通路改善APP/PS1双转基因小鼠的认知功能。方法取7月龄雄性APP/PS1双转基因小鼠30只,按体重随机分为模型对照组和淫羊藿组,每组15只;另取15只同龄的雄性C57BL/6小鼠作为空白对照组。淫羊藿组灌胃给予3 g·kg^(-1)的药物溶液,空白组和模型组给予等体积0.3%CMC-Na,连续灌胃给药28 d,每天1次。筑巢试验检测小鼠日常生活能力;Morris水迷宫试验检测小鼠的学习和记忆能力;苏木素-伊红(H&E)和尼氏(Nissl)染色法观察小鼠脑组织病理学变化;采用TBA法、羟胺法检测小鼠脑组织中丙二醛(malondialdehyde,MDA)和超氧化物歧化酶(superoxide dismutase,SOD)的水平;免疫荧光化学法检测小鼠脑内β-淀粉样蛋白(amyloidβ-protein,Aβ)的表达情况;Western blot法检测环磷酸腺苷效应元件结合蛋白(cAMP response element binding protein,CREB)和脑源性神经营养因子(brain-derived neurotrophic factor,BDNF)信号通路相关蛋白的表达情况。结果与空白组比较,APP/PS1双转基因小鼠的筑巢得分明显降低,逃避潜伏期和游泳距离明显增加(P<0.01),目标象限停留时间和穿越平台次数显著减少;皮层和海马存在明显的神经病理损伤。此外,APP/PS1双转基因小鼠的皮层和海马区域可观察到大量Aβ沉积,并且脑组织中超氧化物歧化酶活性降低,丙二醛水平升高。Western blot结果显示,模型组小鼠脑内环磷酸腺苷效应元件结合蛋白蛋白磷酸化受到抑制,伴随着脑源性神经营养因子蛋白表达明显降低。淫羊藿(3 g·kg^(-1))连续灌胃4周,可明显改善模型小鼠的筑巢能力和认知功能,减轻神经病理损伤,抑制Aβ沉积,减轻氧化应激,促进环磷酸腺苷效应元件结合蛋白环磷酸腺苷效应元件结合蛋白磷酸化,增加脑源性神经营养因子蛋白表达。结论淫羊藿可明显改善APP/PS1双转基因小鼠的认知功能和神经病理损伤,其作用机制可能与激活环磷酸腺苷效应元件结合蛋白/脑源性神经营养因子信号通路有关。

Objective To study whether Epimedium can improve the cognitive function of APP/PS1 double transgenic mice by regulating CREB/BDNF signaling pathway.Methods Thirty 7-month-old male APP/PS1 double transgenic mice were randomly divided into model control group and Epimedium group according to body weight,15 mice in each group.Another 15 male C57BL/6 mice of the same age were taken as the control group.The administration group was given Epimedium 3 g·kg^(-1) by gavage;Blank group and model group were given equal volume of 0.3%CMC-Na by gavage for 28 days,once a day.Morris water maze test was used to detect the learning and memory ability of mice;Pathological changes of brain tissue in mice observed by H&E and Nissl staining;Detection of malondialdehyde(MDA)and superoxide dismutase(SOD)in brain tissue of mice;Detection of amyloidβ-protein(Aβ)expression in mouse brain by immunofluorescence;The expressions of CREB and BDNF signaling pathway related proteins were detected by Western blot.Results Compared with the blank group,the nesting score of APP/PS1 double transgenic mice was significantly decreased,and the escape latency and swimming distance were significantly increased(P<0.01).The target quadrant residence time and the number of crossing platforms are significantly reduced.There were obvious neuropathological damages in cortex and hippocampus.In addition,a large amount of Aβdeposition was observed in the cortex and hippocampus of APP/PS1 double transgenic mice,and the activity of SOD in brain tissue decreased and the level of MDA increased.Western blot results showed that the phosphorylation of CREB protein in the brain of the model group was inhibited,accompanied by a significant decrease in BDNF protein expression.Epimedium(3 g·kg^(-1))for 4 weeks can significantly improve the nesting ability and cognitive function of model mice,reduce neuropathological damage,inhibit Aβdeposition,reduce oxidative stress,promote CREB protein phosphorylation,and increase BDNF protein expression.Conclusion Epimedium improves the cognitive function of APP/PS1 double transgenic mice,which may be related to the activation of CREB/BDNF signaling pathway.