Basing On MTOR Signaling Pathway Studies High Altitude Memory Impairment And Prophylaxis-therapy Of Drug

Objective:1. To study the relationship between the mTOR signaling pathway and high altitude memory impairment and to explore the ameliorating effect of L-leucine on high altitude memory.2. To investigate the influence on high altitude memory and the influence on the mTOR signaling pathways by the intervention of phenylethanoid glycosides of Pedicularis muscicola Maxim. Methods:1. After successfully trained in the 8-arm radial maze, Kunming mice were randomly divided into normoxic control group, hypoxia group, L-leucine low dose group(0.473 g/kg), L-leucine moderate group(0.945 g/kg) and L-leucine high dose group(1.89 g/kg). Mice were given by gavage for 7 days. At the 4th day of the treatment, the mice in the hypoxia and L-leucine groups were placed in a large low-pressure and low-oxygen chamber to simulate hypobaric hypoxia of the high altitude(7500 m, 3 d). The 8-arm radical maze was used to measure the spatial learning and memory ability. HE staining was employed to observe the cell morphological changes in CA1 region of the hippocampus. The expression levels of mTOR, P70S6 K and 4E-BP1 mRNA in the hippocampus were detected by SYBR Green real-time PCR.2. After successfully trained in the 8-arm radial maze, Wistar rats were randomly divided into normoxic control group, hypoxia group, phenylethanoid glycosides low dose group(50 mg/kg), phenylethanoid glycosides moderate dose group(200 mg/kg), phenylethanoid glycosides high dose group(400 mg/kg) and positive control group(1.35 g/kg). Rats were given by gavage for 7 days. At the 4th day of the treatment, the rats in the hypoxia, positive control and phenylethanoid glycosides groups were placed in a large low-pressure and low-oxygen chamber to simulate hypobaric hypoxia of the high altitude(7500 m, 3 d). The 8-arm radical maze was used to measure the spatial learning and memory ability. HE staining was employed to observe the cell morphological changes in CA1 region of the hippocampus. Biochemical technique was used to detect the content of MDA and ROS and enzymatic activity of GSH and SOD in the hippocampus. The mRNA expression levels of mTOR, P70S6 K and 4E-BP1 in the hippocampus were detected by SYBR Green real-time PCR. The protein expression levels of p-mTOR, p-P70S6 K, p-4E-BP1 and Caspase-3 were detected by Western blot. Results:1. Compared with normoxic control group, RME, TE, TT were significantly increased; the neuron damage was exacerbated in CA1 region of the hippocampus; the mRNA expression levels of mTOR and P70S6 K were significantly down regulated and 4E-BP1 were significantly up regulated in hypoxia group when mice was interfered by the L-leucine after hypobaric hypoxia exposure. Compared with hypoxia group, RME, TE, TT and 4E- BP1 mRNA expression had an decreasing tendency and mTOR, P70S6 K mRNA expression had an increasing tendency in the L-leucine low and moderate dose groups, but there are no significant differences; The mice in L-leucine high dose group of RME, TE and TT were significantly decreased and mTOR, P70S6 K mRNA expression were significantly increased; The neuron damage of CA1 region of the hippocampus in L-leucine groups was significantly alleviated.2. Compared with normoxic control group, WME, RME, TE, TT were significantly increased; the neuron damage was exacerbated in CA1 region of the hippocampus; the content of MDA was significantly increased and the enzymatic activity of GSH and SOD was significantly decreased; the mRNA expression levels of mTOR and P70S6 K were significantly down regulated and 4E-BP1 were significantly up regulated; the protein expression levels of p-mTOR and p-P70S6 K were significantly decreased and p-4E-BP1 and Caspase-3 were significantly increased in hypoxia group when rats were interfered by the phenylethanoid glycosides after hypobaric hypoxia exposure. Compared with hypoxia group, The rats in positive control and phenylethanoid glycosides groups of WME, RME, TE, TT were significantly decreased; content of MDA and ROS, enzymatic activity of GSH and SOD, and neuron damage in CA1 region of the hippocampus were significantly improved; the mRNA expression levels of mTOR and P70S6 K were significantly up regulated and 4E-BP1 were significantly down regulated; the protein expression levels of p-mTOR and p-P70S6 K were significantly increased and p-4E-BP1 and Caspase-3 were significantly decreased. Conclusion:1. The mTOR signaling pathway plays an important in the high altitude memory impairment. L-leucine can ameliorate high memory impairment, and the mechanism may involve the activation of mTOR and its downstream substrates(4E-BP1 and P70S6K). The experimental results show that the mTOR signaling pathway can be as potential targets to ameliorate altitude memory impairment.2. Phenylethanoid glycosides of Pedicularis muscicola Maxim can ameliorate high altitude memory impairment, and its mechanism may be to reduce oxidative stress, activate mTOR signaling pathways, and inhibit apoptosis. The experimental results show that phenylethanoid glycosides can adjust the mTOR signaling pathway as a potential drug to ameliorate altitude memory impairment.