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Objective To explore the improving effect of L-leucine on memory impairment in plateau and the mecha-nism. Methods After successfully trained in the 8-arm radial maze,50 male Kunming mice were selected and randomly divid-ed into normoxic control group (NC group),model group,and L-leucine (low,medium and high dose) groups.Animals in L-leu-cine groups were intragastrically given 0.473 g?kg-1 ,0.945 g?kg-1 and 1.89 g?kg-1 L-leucine for 7 days and those in NC and model control groups were administered the same volume of purified water for the same period of time.At the 4th day of the treat-ment,the mice in the model control group and L-leucine groups were placed in a large low-pressure and low-oxygen chamber to simulate low-pressure hypoxic environment of the plateau (7 500 m,3 d).The 8-arm radial maze was used to measure the spatial learning and memory ability of mice and dry-wet method to measure the water content of brain tissue.HE staining was employed to observe the cell morphological changes in CA1 region of the hippocampus.The expression levels of mTOR,P70S6K and 4E-BP1 mRNA in the hippocampus were detected by SYBR Green real-time PCR. Results The reference memory error ( RME) ,total error ( TE) ,testing time ( TT) ,and water content of brain tissue were significantly increased,the neuron injury was exacerbated in CA1 region of the hippocampus,and the expression levels of mTOR and P70S6K mRNA were markedly decreased in model control group when compared with those in NC group (P<0.05 or P<0.01).These indexes,however,were significantly improved in L-leu-cine groups,especially in high-dose group. Conclusion L-leucine can improve memory impairment in plateau,and the mecha-nism may involve the activation of mTOR and its downstream substrates (4E-BP1 and P70S6K).
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<p><b>OBJECTIVE</b>To develop an RP-HPLC method for the determination of five iridoid glycosides in Phlomis younghusbandii.</p><p><b>METHOD</b>HPLC analysis was performed on a Symmetry C18 (4.6 mm x 150 mm, 5 microm, Waters) column eluted with acetonitrile (A) and water (B) in gradient elution. The gradient program was as follows: 0-5 min kept 7% A; 5-10 min changed to 12% A; 10-40 min kept 12% A. The flow rate was 1.0 mL x min(-1). The column temperature was 20 degrees and the detection wavelength was 235 nm.</p><p><b>RESULT</b>The linear ranges of sesamoside, shanzhiside methyl ester, 7, 8-dehydropenstemoside, penstemoside and 8-O-acetylshanzhiside methyl ester were 0.050-0.650 (r = 0.999 3), 0.050-0.350 (r = 0.999 5), 0.040-0.280 (r = 0.999 4), 0.010-0.070 (r = 0.999 6), 0.040-0. 280 (r = 0.999 7) g x L(-1), respectively. The average recoveries (n = 6) of them were all between 96% and 104%, RSD < 5.0%.</p><p><b>CONCLUSION</b>The method is simple, accurate, repeatable and stable, which can be used for quality control of P. younghusbandii.</p>