Study Of Dendrobium Nobile Lindl Alkaloid Against Brain Aging And The Mechanisms In SAMP8 Mice

Objective: To investigate the protective effects of Dendrobium nobile Lindl alkaloid(DNLA)on brain aging in senescence accelerated mouse prone 8(SAMP8)mice,and to explore the possible mechanisms.Methods: 6-month-old SAMP8 mice were randomly divided into four groups as follows: SAMP8 as model group,DNLA low-and high-dose groups,and positive group.Age-matched senescence accelerated mouse resistant 1(SAMR1)mice were used as control.DNLA and metformin were formulated with 1% Tween 80.DNLA low-and high-dose groups and positive drug group were intragastrically administered with DNLA 20,40 mg/kg and metformin 80 mg/kg once a day for 6 months,while the SAMR1 and SAMP8 group were administered with volume-matched of 1% Tween 80.Before the end of DNLA and metformin administration,Morris water maze test,Y maze test,Object recognition test,Rotating rod test and Open field test were applied to evaluate learning and memory ability and motor function.Body weight and brain weight were measured to determine the wet weight ratio of brain.SA-?-gal staining was used to identify the brain aging.The neuronal morphological changes and injury in hippocampus CA1 region and cortex were examined via H&E staining and Nissl staining.Western blot was used to detect the aging protein level of Klotho,the A? production and degradation pathway related protein levels of A?,APP,PS1,BACE1,IDE,NEP and autophagy-related protein levels of LC3 B,Beclin1,P62.Results: Compared with SAMR1,the escape latency of SAMP8 mice was prolonged,time percentage in the target quadrant and the percentage of spontaneous alternation in Y maze test were significantly decreased,the percentage of exploring new objects of total time was no decreased,escape latency of Rotating rod test was shortened,the total distance of movement in the central and peripheral areas has significantly shortened.The ratio brain weight/body weight was decreased.The results of SA-?-gal staining indicated the number of aging cells in SAMP8 mouse brain was increased.Pyramidal cells arranged in disorder,neuronal injury and decreased number of Nissl bodies in the hippocampus CA1 region and cortex were found.The protein expression of A?,APP,BACE1,PS1 and P62 in the hippocampus and cortex was increased,while the expression of LC3 B,Beclin1,IDE,NEP and Klotho decreased.However,compared with SAMP8 mice,after DNLA and metformin administration,obviously improved the escape latency,time percentage in the target quadrant and the percentage of spontaneous alternation in Y maze test were increased,the percentage of exploring new objects of total time was no increased,the escape latency of Rotating rod test was prolonged,the total distance of movement in the central and peripheral areas has no significantly changed.It was discovered that the ratio of brain weight/body weight was markedly increased.The results of SA-?-gal staining showed that the number of aging cells was decreased.Meanwhile,the hippocampus CA1 region and cortex neurons were arranged with regular and significantly increased the number of Nissl bodies.Moreover,in the hippocampus and cortex,the protein level of A? was significantly lower,but the aging protein level of Klotho was higher,the production of A? metabolic pathway related protein APP,BACE1,PS1 were significantly reduced,the related protein of A? degrading enzymes IDE and NEP were significantly increased,while the autophagy-related protein level of P62 was decreased,the protein levels of LC3 B,Beclin1 were significantly enhanced.Conclusion: DNLA can delay aging,the anti-aging mechanism of DNLA may be mediated via up-regulating the protein level of Klotho,decreasing A? aggregation and enhancing the autophagy activity.