苯乙醇苷类化合物通过PI3K/Akt/mTOR-HIF-1α信号通路对高原低氧大鼠认知功能损伤的保护作用

Neuroprotective effects of phenylethanoid glycosides on hypoxic-induced cognitive impairment in rat via the PI3K/Akt/mTOR-HIF-1α pathway

目的研究毛蕊花糖苷、松果菊苷及酪醇等苯乙醇苷类化合物对高原低氧大鼠认知功能损伤的保护作用及机制。方法采用八臂迷宫训练大鼠认知能力,随机取72只训练成功的大鼠并分为6组:常氧空白组(蒸馏水,2 ml/200 g)、低氧模型组(蒸馏水,2 ml/200 g)、毛蕊花糖苷组(150 mg/kg)、松果菊苷组(150 mg/kg)、酪醇组(150 mg/kg)及红景天苷组(150 mg/kg),每组12只。连续灌胃给药7 d。第4天给药后,除常氧空白组置于常氧(海拔1500 m)外,其余组置于大型模拟高原低氧环境动物实验舱(海拔7500 m,72 h)。低氧暴露前后八臂迷宫测试(海拔4000 m)评价其认知功能,HE染色观察海马组织病理学改变,并测定相关组织中活性氧(ROS)、丙二醛(MDA)、还原型谷胱甘肽(GSH)含量及超氧化物歧化酶(SOD)活性,PCR及West⁃ern印迹法检测海马组织中PI3K/Akt/mTOR-HIF-1α信号通路相关mRNA及蛋白表达。结果与常氧空白组相比,低氧组大鼠记忆相关指标错误率显著升高(均P<0.01),低氧模型组海马结构明显损伤,海马组织ROS、MDA及血清MDA显著升高(均P<0.01),海马组织和血清GSH含量、SOD活性显著降低(均P<0.01),PI3K/Akt/mTOR-HIF-1α信号通路被抑制(P<0.01);与低氧模型组相比,各给药组对大鼠相关指标均有改善作用,其中酪醇组的效果最好,大鼠记忆错误率有所下降(P<0.01),海马结构损伤减轻,海马组织ROS、MDA及血清MDA含量都呈现不同程度的降低(P<0.01),海马组织和血清GSH含量、SOD活性呈现不同程度的升高(P<0.01),PI3K/Akt/mTOR-HIF-1α信号通路相关mRNA及蛋白表达有所改善(P<0.01)。结论毛蕊花糖苷、松果菊苷、酪醇及红景天苷对高原低氧认知功能损伤有一定的保护作用,其中酪醇效果最明显。其机制可能与抑制组织损伤、抗氧化应激及改善PI3K/Akt/mTOR-HIF-1α信号通路有关。

Objective To investigate the neuroprotective effects and action mechanisms of acteoside,echinacoside and tyro⁃sol on the environmental hypoxia-induced cognitive impairment in rats.Methods The 8-arm radial maze was used to train the cogni⁃tive function of rats.The 72 SPF Wistar rats were randomly divided into normoxic group(distilled water,2 ml/200 g),hypoxic group(distilled water,2 ml/200 g),acteoside(150 mg/kg),echinacoside(150 mg/kg),tyrosol(150 mg/kg)and rhodioside(150 mg/kg)groups after cognitive training.Rats in each group were orally administered drugs or water once a day for continuous 7 days.After drug administration in the fourth day,mice in the hypoxic,acteoside,echinacoside,tyrosol and rhodioside groups were exposed to a simu⁃lated altitude of 7500 m for 72 h in hypobaric hypoxic animal experiment chamber.The 8-arms radial maze was used(4000 m)to eval⁃uate their cognitive function before and after exposure to the hypoxic conditions,while HE staining was used to observe the histopatho⁃logical changes of hippocampus.The content of malondizldehyde(MDA),reactive oxygen species(ROS)and reduced glutathione(GSH)as well as the enzymatic activity of superoxide dismutase(SOD)in hippocampus and/or plasma were tested.The PCR and West⁃ern blotting were used to detect the PI3K/Akt/mTOR-HIF-1αsignaling pathway-related transcript mRNA and protein expression level in hippocampal tissues.Results Compared with the normoxic group,hypoxia induced an obvious increase in cognition error(P<0.01)and damage on the hippocampus.The content of ROS and MDA in hippocumpus and the plasma MDA content were increased,while the CSH content in both hippocampus and plasma as well as the enzymatic activity of SOD were decreased significantly(P<0.01).The PI3K/Akt/mTOR-HIF-1αsignaling pathway was significantly inhibited(P<0.01).Compared with the hypoxic group,the test groups all showed an improvement effect on the tested parameters and the best effect was observed in the tyrosol group.The cognition error(P<0.01)and damage on the hippocampus were ameliorated after administration of the drugs.The content of ROS and MDA in hippocampus and the plasma MDA content were decreased,while the CSH content in both hippocampus and plasma as well as the enzymatic activity of SOD were increased,all significantly,but to different levels(P<0.01).The PI3K/Akt/mTOR-HIF-1αsignaling pathway-related transcript mRNA and protein expression level was also ameliorated to a certain extent(P<0.01).Conclusion Acte⁃oside,echinacoside,tyrosol and rhodioside exhibited neuroprotective effects on the hypoxia-induced cognitive impairment in rats,and tyrosol showed the best protective effect.The mechanism was likely related to the inhibition of tissue damage,the anti-oxidative effect and the activation of PI3K/Akt/mTOR-HIF-1αsignaling pathway.