Effects Of Dendrobium Nobilis Lindl.alkaliod On SAMP8 Mice Fed With A High Methionine Diet

Objective: To investigate the effects of Dendrobium nobile Lindl.alkaloid(DNLA)on the aging of SAMP8 model mice,and to explore whether the mechanism was related to DNA Methylation and the p53 signaling pathway.Methods: In this study,4-month-old male SAMR1 and SAMP8 model mice were randomly divided into 5 groups(10 mice per group): SAMR1 group,SAMP8 group,SAMP8+MET group,DNLA-10 mg/kg group and DNLA-20 mg/kg group.Mice in SAMP8+ MET group,DNLA-10 mg/kg group and DNLA-20 mg/kg group were given a maintenance diet containing 2% Methionine(MET)from the age of 4 months,and were given intragastric administration once a day for 5 consecutive months from the age of 6months.Before the end of administration,the short-term learning and memory ability of the experimental mice was detected by the behavioral Y maze test.The activities of total superoxide dismutase(T-SOD)and glutathione peroxidase(GSH-Px)in serum of mice were determined by ELISA.H&E staining and Nissl staining were used to observe the damage of cerebral cortex neurons in mice.Immunofluorescence(IF)was used to detect the expression level of 5-Methylcytosine(5-MC)in the cerebral cortex of experimental mice.The expression of anti-aging protein Klotho protein,the expression of key proteins in the age-related p53 pathway(p53,p21,CDK2,CDK4,PRb and Rb),and the expression of DNA Methylation related proteins(DNMT1 and DNMT3A)in the cortex of mice were determined by Western blot.Results: Compared with SAMR1 control group,the accuracy of spontaneous Y maze alternation in SAMP8 mode mice decreased.Serum total superoxide dismutase activity decreased;The activity of glutathione peroxidase decreased significantly.The cortical neurons of mice were disordered with obvious nuclear pyknosis,and the number of normal neurons was significantly reduced.The expression level of 5-Methylcytosine in the cortex was decreased.The expression levels of anti-aging protein Klotho protein in cortex were significantly decreased,the expression levels of CDK4 protein in p53 pathway were decreased,the expression levels of CDK2 protein and PRb protein were significantly decreased,the expression levels of p53,p21 protein and Rb protein were significantly increased,and the expression levels of DNMT1 and DNMT3 A protein were significantly increased.Compared with SAMP8 mice,the correct rate of spontaneous alternation of Y maze in SAMP8+MET group had no significant change.The activity of total superoxide dismutase in serum was significantly decreased.The activity of glutathione peroxidase increased significantly.There was no significant difference in the cortical neurons of mice.There was no significant change in the expression level of5-Methylcytosine in cortex.There were no significant changes in the expression levels of anti-aging protein Klotho,protein expressions of p53,p21,CDK2,CDK4,p Rb and Rb in the p53 pathway,and protein expressions of DNMT1 and DNMT3 A in the cortex.Compared with SAMP8+MET group,the correct rate of spontaneous Y maze alternation behavior of mice in DNLA-20 mg/kg group was significantly higher.The activities of total superoxide dismutase(TSOD)and glutathione peroxidase(GSH)in serum were significantly increased.The cortical neurons of mice were arranged regularly,nuclear pyknosis was improved,and the number of normal neurons increased significantly.The expression level of 5-Methylcytosine in cortex was significantly increased.The expression of anti-aging Klotho protein and CDK4 protein in the P53 pathway in the cortex were increased,the expression of CDK2 and p Rb protein were significantly increased,the expression of p53,p21 and Rb protein were significantly decreased,and the expression of DNMT1 and DNMT3 A protein were significantly decreased.Conclusion:(1)The Dendrobium nobile Lindl.alkaloid could delay the aging of SAMP8 mice and improve the short-term learning and memory impairment caused by aging;(2)The mechanism of anti-aging effect of Dendrobium nobile Lindl.alkaloid is related to the down-regulation of P53 signaling pathway;(3)The mechanism of anti-aging effect of Dendrobium nobile Lindl.alkaloid is related to the decreased expression of DNA Methyltransferase mediated by the increase of P53 protein.