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Objective@#To explore the protective effect and mechanism of the dihydromyricetin (DHM) on cognitive dysfunction in Alzheimer’s disease (AD) rat model.@*Methods@#The AD model of rats was established by injecting Aβ1-42 oligomolymer into the hippocampus. According to the random number table, 30 successfully constructed AD model rats were divided into AD group, AD+ DHM1 group and AD+ DHM2 group, with 10 in each group.And the rats in the three groups were intraperitoneally injected with normal saline, 100 mg/kg DHM and 200 mg/kg DHM for 21 days, respectively.Another 10 rats with body mass matching were taken as the control group.Morris water maze was used to evaluate the spatial learning and memory ability of rats in each group, the expression of inflammatory cytokines were detected by Elisa, and the expressions of AMPK and SIRT1 proteins were detected by Western blot.@*Results@#Compared with the control group, the escape incubation period of rats in AD group was prolonged, and the difference was statistically significant (day 5 : (10.36±2.80)s, (22.40±2.98)s; t=-18.63, P<0.05). Compared with AD group, the escape latency of rats in AD+ DHM1 group and AD+ DHM2 group were shortened (day 5: AD+ DHM1 group (15.68±3.06) s, AD+ DHM2 group (18.85±3.22) s; t=10.65, 4.13, both P<0.05). Compared with AD group, rats in AD+ DHM1 group and AD+ DHM2 group had more crossing times ((1.87±0.76), (2.75±0.63) and (3.78±0.71); t=-6.86, -9.83, both P<0.05), and the target quadrant residence time were extended ((17.08±1.99) s, (16.33±4.33) s, (22.59±4.21) s; t= 28.5, 8.63, both P<0.05). Compared with the control group, the levels of IL-1β, IL-6 and TNF-α in the serum and hippocampus of the AD group were significantly increased (serum: t=4.98, 7.87, 5.43, all P<0.05; hippocampus: t=11.13, 30.50, 23.38, all P<0.05). Compared with the AD group, the levels of IL-1β, IL-6 and TNF-α in the serum and hippocampus of the AD+ DHM1 group and the AD+ DHM2 group were significantly decreased, the difference was statistically significant(serum: AD+ DHM1 group t=-4.13, -10.70, -9.22, AD+ DHM2 group t=-1.75, -3.63, -18.75, all P<0.05; hippocampus: AD+ DHM1 group t=-69.13, -15.13, -6.50, AD+ DHM2 group t=-10.25, -39.00, -8.00, all P<0.05). Compared with the control group, the expression of p-AMPK/AMPK protein and SIRT1 protein in the AD group were decreased.The expression of the two proteins in the AD+ DHM1 group and the AD+ DHM2 group were increased, comparing with those of AD group, and the difference was statistically significant(all P<0.05).@*Conclusion@#DHM exerts protective role in AD model rats, which may be related to the activation of AMPK/SIRT1 pathway and the inhibition of inflammatory response.
ABSTRACT
Objective To explore the protective effect and mechanism of the dihydromyricetin (DHM) on cognitive dysfunction in Alzheimer’s disease (AD) rat model. Methods The AD model of rats was established by injecting Aβ1-42 oligomolymer into the hippocampus. According to the random number table,30 successfully constructed AD model rats were divided into AD group,AD+DHM1 group and AD+DHM2 group,with 10 in each group. And the rats in the three groups were intraperitoneally injected with nor-mal saline,100 mg/kg DHM and 200 mg/kg DHM for 21 days,respectively. Another 10 rats with body mass matching were taken as the control group. Morris water maze was used to evaluate the spatial learning and memory ability of rats in each group,the expression of inflammatory cytokines were detected by Elisa,and the expressions of AMPK and SIRT1 proteins were detected by Western blot. Results Compared with the con-trol group,the escape incubation period of rats in AD group was prolonged,and the difference was statistically significant (day 5 :(10. 36±2. 80)s,(22. 40±2. 98)s;t=-18. 63,P<0. 05). Compared with AD group,the escape latency of rats in AD+DHM1 group and AD+DHM2 group were shortened (day 5:AD+DHM1 group (15. 68±3. 06) s,AD+DHM2 group (18. 85±3. 22) s; t=10. 65,4. 13,both P<0. 05). Compared with AD group,rats in AD+DHM1 group and AD+DHM2 group had more crossing times ((1. 87± 0. 76),( 2. 75± 0. 63) and (3. 78±0. 71);t=-6. 86,-9. 83,both P<0. 05),and the target quadrant residence time were ex-tended ((17. 08±1. 99) s,(16. 33±4. 33) s,(22. 59±4. 21) s;t= 28. 5,8. 63,both P<0. 05). Compared with the control group,the levels of IL-1β,IL-6 and TNF-α in the serum and hippocampus of the AD group were significantly increased (serum: t=4. 98, 7. 87, 5. 43, all P<0. 05; hippocampus: t=11. 13, 30. 50, 23. 38,all P<0. 05). Compared with the AD group,the levels of IL-1β,IL-6 and TNF-α in the serum and hippocampus of the AD+DHM1 group and the AD+DHM2 group were significantly decreased,the difference was statistically significant ( serum: AD+DHM1 group t=-4. 13,-10. 70,-9. 22, AD+DHM2 group t=-1. 75,-3. 63,-18. 75,all P<0. 05;hippocampus:AD+DHM1 group t=-69. 13,-15. 13,-6. 50,AD+DHM2 group t=-10. 25,-39. 00,-8. 00,all P<0. 05). Compared with the control group,the expression of p-AMPK/AMPK protein and SIRT1 protein in the AD group were decreased. The expression of the two pro-teins in the AD+DHM1 group and the AD+DHM2 group were increased,comparing with those of AD group, and the difference was statistically significant(all P<0. 05). Conclusion DHM exerts protective role in AD model rats,which may be related to the activation of AMPK/SIRT1 pathway and the inhibition of inflammato-ry response.
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AIM: To construct HBx eukaryotic expression vector pEYFP-C1-X and eukaryotic expression vector pGL3-P4 driven by P4 promoter of human IGF-II gene and to investigate the effect of HBx on the transcription activity of IGF-II gene P4 promoter. METHODS: HBx gene and P4 promoters were cloned into pEYFP-C1 and pGL3-basic vectors respectively by gene recombination techniques to construct recombinant plasmids pEYFP-C1-X and pGL3-P4. HepG2 cells were transfected with pEYFP-C1-X and the resistant cell clones were selected by G418. Then methylated pGL3-P4 was transiently transfected into the above cell clones, and the transcription activity of P4 promoter was determined by dual-luciferase reporter assay system. RESULTS: (1) Aim fragments HBx gene and P4 promoter that were cloned were 465 bp and 1 246 bp, respectively and the DNA sequences were accordant with GenBank data confirmed by restricted enzyme digestion and sequencing. (2) HepG2-EYFP-X cells that expressed HBx protein were obtained. (3) Luciferase activity of methylated P4 promoter in the HepG2-EYFP-X was more than that of control cell HepG2-EYFP (P<0.01). CONCLUSION: HBx may enhance the transcription activity of the P4 promoter.