| Objective:To investigate the protective effect of chlorogenic acid?CGA?on cognitive function in model mice with Alzheimer's disease?AD?,and to explore its possible mechanisms.Methods:?1?50 SPF Kunming mice,half male and half female,according to the results of behavioral test results and body weight were randomly divided into three groups as control group,AD model group,and CGA group.CGA group was divided into three dose treatment groups with 10 mice in each group.control group was given saline intraperitoneal 0.2 mL injection and distilled water 0.15 mL intragastric administration for 12 weeks.Other groups were established with D-galactose 120 mg·kg-1·d-1 intraperitoneal injection and AlCl3 20 mg·kg-1·d-1 intragastric administration continuously for 12 weeks.Since the 7 th week,control group and AD model group were treated with distilled water 0.15 m L intragastric administration two times a day for 6 weeks.CGA groups were given CGA intragastric administration 50 mg·kg-1·d-1,100 mg·kg-1·d-1,200 mg·kg-1·d-1 respectively for 6 weeks.?2?The model has been achieved 12 weeks later.The learning and memory ability was tested by morris water maze test and step-down test of each group.?3?The activity of Superoxide dismutase?SOD?,and Glutathione peroxidase?GSH-PX?and the content of malondialdehyde?MDA?in brain and serum were measured by colorimetric method.?4?The expression of A?1-42 in mice hippocampus was tested by ELISA in each group.?5?The expression of beta amyloid protein1-42(A?1-42),Phosphorylation of tau protein?p-tau?and Cysteine-containing aspartate-specific protease 3?Caspase-3?in hippocampus CA1 and CA3 areas of mice in each group were observed by immunohistochemistry staining method.?6?The expression of?eta-Amyloid precursor protein?APP?,A?1-42,p-tau,Toll-like receptor 4?TLR4?,Myeloid differentiation factor 88?Myd88?,Nuclear factor-?B?NF-?B?,Tumor necrosis factor-??TNF-??,Interleukin-6?IL-6?,B-cell lymphoma-2?Bcl-2?,Bcl-2 Associated X Protein?Bax?,Bax/Bcl-2,Cytochrome c?Cyt-c?,pro-caspase-3,Caspase-3mammalian target of rapamycin with phosphorylation?p-mTOR?and Microtubule-associated protein 1 light chain 3B?LC3B?in mice hippocampus of each group were measured by western blot.Results:?1?The water-maze test results showed that in model group,compared with control group the escape latency was prolonged,the quadrant entries times and target quadrant time were decreased?P<0.05?.In different dose of CGA groups,compared with model group the escape latency was shortened,the quadrant entries times and target quadrant time were increased?P<0.05?.Comparison between different dose of CGA groups,CGA-200 group had the most obvious improvement in cognitive function.with statistic difference?P<0.05?.?2?The step-down test results showed that in model group,compared with control group training error numbers and after training error numbers were increased,the latency were shortened,with statistic difference?P<0.05?.In different dose of CGA groups,compared with model group training error numbers and after training error numbers were decreased,the latency was prolonged,with statistic difference?P<0.05?.Comparison between different dose of CGA groups,the improvement of learning and memory in CGA-200 group was most obvious with statistic difference?P<0.05?.?3?In model group,compared with control group the activity of SOD and GXH-Px were decreased and the content of MDA was increased in brain tissue and serum?P<0.05?with statistic difference?P<0.05?.In different dose of CGA groups,compared with model group the activity of SOD and GSH-PX were increased and the content of MDA was decreased in brain tissue and serum?P<0.05?with statistic difference?P<0.05?.Comparison between different dose of CGA groups,the changes of SOD,GSH-PX activity and MDA content in the brain tissue and serum of CGA-200 group were most obvious with statistic difference?P<0.05?.?4?The ELISA results showed that in model group,compared with control group the expression of A?1-42 in mice hippocampusl was increased?P<0.05?.In different dose of CGA groups,compared with model group the expression of A?1-42 in mice hippocampus were decreased?P<0.05?.Comparison between different dose of CGA groups,the decrease of the expression of A?1-42 in mice hippocampus in CGA-100 group was most obvious.with statistic difference?P<0.05?.?5?Immunohistochemistry results showed that in model group,compared with control group the expression of A?1-42,p-tau and Casepase-3 in hippocampus CA1 and CA3 areas of mice in each group were increased?P<0.05?.In different dose of mice intervention groups,compared with model group the expression of A?1-42,p-tau and Casepase-3 in hippocampus CA1 and CA3 areas of mice in each group were decreased?P<0.05?.Comparison between different doses of CGA groups,the expression of A?1-42 and Casepase-3 in hippocampus CA1 and CA3 areas of mice in CGA-100 group was decrease significantly,and the expression of p-tau in hippocampus CA1 and CA3 areas of mice in CGA-200 group was decrease significantly with statistic difference?P<0.05?.?6?The Western bolt results showed that in model group,compared with control group the expression of APP,A?1-42,p-tau,TLR4,Myd88,NF-?B,TNF-?,IL-6,Bax,Bax/Bcl-2,Cyt-c,Caspase-3,p-mTOR and LC3B in mice hippocampus were increased,Bcl-2 and pro-caspase-3 in mice hippocampus were decreased with statistic difference?P<0.05?.In different doses of CGA groups,compared with model group the expression of APP,A?1-42,p-tau,TLR4,Myd88,NF-?B,TNF-?,IL-6,Bax,Bax/Bcl-2,Cyt-c,Caspase-3 and p-mTOR in mice hippocampus were decreased,Bcl-2 and pro-caspase-3 and LC3B in mice hippocampus were increased with statistic difference?P<0.05?.Comparison between different doses of CGA groups,the expression of APP,A?1-42,NF-?B,Bax,Bax/Bcl-2,Cyt-c and Caspase-3 in hippocampus in CGA-100 group was decreased significantly,but the expression of Bcl-2 and pro-caspase-3 was increased significantly.The expression of p-tau,TLR4,Myd88,TNF-?,IL-6 and p-mTOR in CGA-200 group was decreased significantly,but the expression LC3B was increase significantlywith statistic difference?P<0.05?.Conclusion:CGA can decrease the expression of APP,A?1-42,p-tau and improve its neurotoxicity and may improve cognitive function of AD model mice,which possible mechanism may be related to the following four points.?1?CGA can improve the antioxidant capacity through increase the activity of SOD and GSH-PX and decrease the content of MDA.The effect of CGA which dosage is 200 mg·kg-1·d-1 is significant.?2?CGA can alleviate neuroinflammation through inhibiting the signal pathway of TLR4/Myd88/NF-?B and the expression of TNF-?and IL-6.The effect of CGA which dosage is 200 mg·kg-1·d-1 is significant.?3?CGA can reduce neuron apoptosis through decreasing the expression of Bax/Bcl-2,Cyt-c,Caspase-3 and increasing the expression of pro-caspase-3.The effect of CGA which dosage is 100 mg·kg-1·d-1is significant.?4?CGA can modulate the autophagy of neurons through decreasing the expression of p-mTOR and increasing the expression of LC3B.The effect of CGA which dosage is 200 mg·kg-1·d-1 is significant. |
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