| Objective 1.To study the effects of different altitude and exposure duration of simulated hypoxia on PI3K/Akt/mTOR-HIF-1? signaling pathway in hippocampus tissues of rats.2.To investigate the effects of acteoside on PI3K/Akt/mTOR-HIF-1? signaling pathway in hippocampus tissues of rats in hypoxia environment.3.To compare the effects of acteoside,echinacoside and tyrosol on PI3K/Akt/mTOR-HIF-1? signaling pathway in hippocampus tissues of rats in hypoxia environment.Methods 1.A total of 72 SPF male Wistar rats were randomly divided into normoxic group and 3000 m,4500 m,6000 m,7500 m and 8000 m hypoxic groups(n=12).Normoxic group was placed in normoxia circumstances of Lanzhou(1500 m altitude),while other five groups were placed in hypobaric hypoxic animal experiment chamber for hypoxic exposure at different altitudes.After hypoxic exposure for 12 h,pathological changes of hippocampus tissues were observed by HE staining,mRNA and protein expressions of PI3K/Akt/mTOR-HIF-1? signaling pathway were detected by PCR and western blot.The most obvious hypoxic exposure elevation was confirmed according to experimental results of hippocampal tissue damage and PI3K/Akt/mTOR-HIF-1? signaling pathway variation,and then 72 SPF male Wistar rats were randomly divided into normoxic group,6 h,12 h,24 h,36 h and 72 h hypoxic groups.Normoxic group was placed in normoxia circumstances of Lanzhou(1500 m altitude),while other five groups were placed in hypobaric hypoxic animal experiment chamber at 7500 m altitude for hypoxic exposure at different duration.The pathological changes of hippocampus tissues were observed by HE staining,and the expressions of PI3K/Akt/mTOR-HIF-1? signaling pathway were detected by PCR and western blot.2.After successfully trained in the 8-arms radial maze,72 SPF male Wistar rats were randomly divided into normoxic group(distilled water,2.0 ml/200 g),hypoxic group(distilled water,2.0 ml/200 g),acteoside low,medium and high dose groups(50,150,300 mg/kg),positive group(L-Leucine,1.35 g/kg).Each group was administered for a week.When drug delivery in the fourth day,hypoxic,acteoside groups and positive group were exposed to a simulated of 7500 m in hypobaric hypoxic animal experiment chamber.Then 8-arms radial maze was used to evaluate cognitive function before and after hypoxia(4000 m),HE staining was used to observe the histopathological changes in the hippocampus,and biochemical technique was used to detect the content of ROS in hippocampus,the content of MDA ? GSH and the enzymatic activity of SOD in serum and hippocampus.The expression of mRNA and protein expression of the PI3K/Akt/mTOR-HIF-1? signaling pathway in hippocampal tissues detected by PCR and western blot.3.8-arm radial maze was used to train the cognitive function of rats,then 60 SPF male Wistar rats were randomly divided into normoxic group(distilled water,2.0 ml/200 g),hypoxic group(distilled water,2.0 ml/200 g),acteoside(150 mg/kg),echinacoside(150 mg/kg)and tyrosol(150 mg/kg)groups after successfully trained in the 8-arms radial maze.Each group was administered for a week.When drug delivery in the fourth day,hypoxic,acteoside,echinacoside and tyrosol groups rats were exposed to a simulated of 7500 m in hypobaric hypoxic animal experiment chamber.8-arms radial maze was used to evaluate cognitive function before and after hypoxia(4000 m),HE staining was used to observe the pathological changes in the hippocampus,and biochemical technique was used to detect the content of ROS in hippocampus,the content of MDA?GSH and the enzymatic activity of SOD in serum and hippocampus.The expression of mRNA and protein expression of the PI3K/Akt/mTOR-HIF-1? signaling pathway in hippocampal tissues detected by PCR and western blot.Results 1.In the normoxic group,the hippocampal structure of the rats was complete,and the cells were arranged neatly.However,with elevated hypoxia altitude and prolongating hypoxia duration,the structure became loose and edema,neurons showed different degrees of degeneration and necrosis,PI3K/Akt/mTOR-HIF-1? signaling pathway was gradually inhibited,especially hypoxia lasting 72 h at 7500 m,PI3K/Akt/mTOR-HIF-1? was strongest inhibited and the organism was suffered the most severe hypoxia-injury.2.Compared with the normoxic group,the indicators(WME,RME,TE,and TT)of the 8-arm radial maze were increased and the hippocampus was significantly damaged in hypoxic group.The content of ROS was increased in hippocampus.The content of MDA was increased in hippocampus and serum while the content of GSH the enzymatic activity of and SOD were respectively decreased.The PI3K/Akt/mTOR-HIF-1? signaling pathway was inhibited.Compared with the hypoxic group,the indicators of the 8-arm radial maze were decreased and the degree of hippocampus injury was relieved in the acteoside low,medium and high dose groups.The hippocampal ROS,MDA,and serum MDA was reduced and the content of GSH and enzymatic activity of SOD were respectively increased.The PI3K/Akt/mTOR-HIF-1? signaling pathway was already redressed.3.Compared with the normoxic group,the indicators of the 8-arm radial maze were increased and the hippocampus was significantly damaged in hypoxic groups.The content of MDA was increased in hippocampus and serum while the enzymatic activity of GSH and SOD were respectively decreased.The content of ROS was increased in hippocampus.The PI3K/Akt/mTOR-HIF-1? signaling pathway was inhibited.Compared with the hypoxic group,acteoside,echinacoside and tyrosol,which belong to phenylethanoid glycosides,redress indicators of varying degrees and adjust PI3K/Akt/mTOR-HIF-1? signaling pathway.Conclusion 1.With increasing hypoxia altitude and prolongating hypoxia duration,PI3K/Akt/mTOR-HIF-1? signaling pathway was gradually inhibited,especially hypoxia lasting 72 h at 7500 m.2.Acteoside have certain neuroprotective effects on hypoxic-induced cognitive impairment rats.The mechanism may be related to the inhibition of tissue damage and antioxidant stress and redress of PI3K/Akt/mTOR-HIF-1? signaling pathway.3.Acteoside,echinacoside and tyrosol have certain neuroprotective effects on hypoxic-induced cognitive impairment rats.The mechanism may be related to the reduction of tissue damage and antioxidant stress and redress of PI3K/Akt/mTOR-HIF-1? signaling pathway. |
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