| ObjectiveAlzheimer’ s disease(AD)is a type of disease that occur in the elderly,with recent memory disorder as the main clinical symptoms.Senile plaques(SP),neuronal fiber tangles(NFT),and neuronal loss are the main pathological changes of AD,which is a progressive neurodegenerative disease.According to the World Health Organization,10%of elderly people over the age of 65 in the world today will develop Alzheimer’ s disease,and by the age of 80,the proportion will rise to more than 40%.Currently,there are about 29 million AD patients in the world.The average survival time of the AD patients is 5 to 10 years.AD is the fourth leading cause of death in the elderly,only next to heart disease,malignancy,and stroke.According to the proportion of the elderly population and morbidity forecast,the number of patients with Alzheimer’ s disease in China has more than 10 million,accounting for 40%of the Asia-Pacific region,accounting for about 1/4 of the world.Our country has become the country with the most patients with Alzheimer’ s disease in the whole world.The social,economic,family and public health problems caused by Alzheimer’ s disease have become the focus of the governments,the public,and medical workers.The problems and challenges that Alzheimer’s disease brought to our country are more than any other country in the whole world.AD is a degenerative disease of the central nervous system(CNS)which is mainly composed of cognitive disorder and learning and memory impairment.However,no drug has been developed to treat AD effectively or to block the pathological progress of AD.Bajijiasu is a monomer isolated from Morinda Officinalis.It has the advantages of high safety,exact efficacy,and easy availability.Bajijiasu has great value in the treatment of AD,and its target remains to be further explored.The purpose of this study was to investigate the effect of Baji jiasu on the formation and degradation of A β in AD,and the effect on the pathologic and behavioral features in APP/PS1 double transgenic mice.We also observed the effects of Bajijiasu on the neurotrophic factors expression,neuroinflammatory factor expression and synaptic structural stability in APP/PS1 double transgenic mice.This work is to elucidate the mechanism and possible targets of Bajijiasu on neuroprotective effect and to provide a scientific basis for the development of anti-AD drugs.MethodIn this study,Morris water maze and new object recognition experiments were used to observe the effect of Bajijiasu on learning and memory abilities in APP/PS1 double transgenic mice.7-month-old APP/PS1 double transgenic male mice were randomly divided into the model group,the low-dose group of Bajijiasu,and the high-dose group of Bajijiasu,which were designed according to the principle of weight close,10 mice in each group.10 non-transgenic C57BL/6J mice were selected as the wild group.All mice were housed in SPF grade room of Experimental Animal Center of Guangzhou University of Chinese Medicine.The low-dose group of Bajijiasu was given 20mg/Kg/d,and the high-dose group of Bajijiasu was given 80mg/Kg/d.The mice in the wild group and the model group were treated with equal volume of distilled water.All the mice were given intragastric administration one time per day,continuous administration for 4 weeks,then,followed by Morris water maze and the new object recognition tests.Effects of Bajijiasu on the metabolism of A β in the brain of APP/PS1 double transgenic mice:The mRNA levels of APP and PS1 in brain of APP/PS1 double transgenic mice were detected by real-time fluorescent quantitative PCR.The Aβ production and degradation related protein APP,PS1,BACE1,NEP,and IDE in the brain of APP/PS1 double transgenic mice were detected by Western Blot.The alterations of Aβ 1-42 in the brain of APP/PS1 double transgenic mice were detected by ELISA.The number of senile plaques in the brain of APP/PS1 double transgenic mice was detected by the method of thioflavin-S staining.Effects of Bajijiasu on the expression of neurotrophic factors in the brain of APP/PS1 double transgenic mice:The alterations of neurotrophic factors BDNF and NGF in the brain of APP/PS1 double transgenic mice were detected by Western Blot.Effects of Bajijiasu on the expression of neuroinflammatory factors in the brain of APP/PS1 double transgenic mice:Western Blot was used to detect the expression of NF-K B,TNF-α,and IL-1 p,which are related to central nervous system inflammation in the brain of APP/PS1 double transgenic mice.Effects of Bajijiasu on the synaptic structure stability in the brain of APP/PS1 double transgenic mice:The synaptic structure related protein,including SYN,PSD-93,and PSD-95 in the brain of APP/PS1 double transgenic mice were analyzed by Western Blot.Resu t1.Effects of Bajijiasu on learning and memory abilities of APP/PS1 double transgenic miceThe Morris water maze test results showed that during the 5-day positioning navigation test,the escape latency of mice in each group showed a tendency to shorten the training time.Compared with the model group,the escape latency of mice in wild group was significantly shorter(P<0.01),and the escape latency of the low-dose and high-dose groups of Bajijiasu were shorter than the model group(P<0.05,P<0.01).Compared with the model group,the number of crossing the location of the platform and the time of staying in the target quadrant of mice in wild group were significantly increased in the space exploration test(P<0.01,P<0.01).The number of crossing the location platform and the time of staying in the target quadrant of mice in the high-dose group of Bajijiasu were also higher than those in the model group(P<0.01,P<0.05).The results of the new object recognition test showed that there was no significant difference in the degree of preference between any two groups on the second day of the test(P>0.05).On the third day,compared with the model group,the preference index of the wild group was significantly higher(P<0.01),and the preference index of the high-dose group of Bajijiasu was also higher than the model group(P<0.05).2.Effects of Bajijiasu on metabolism of A β in the brain of APP/PS1 double transgenic miceThe results of Fluorescence quantitative PCR showed that there was no significant difference in the gene levels of APP and PS1 in the brain of APP/PS1 double transgenic mice(P>0.05).The results of Western Blot showed that there was no significant difference in the protein level of APP and PS1 in the brain of APP/PS1 double transgenic mice(P>0.05).Compared with the model group,the Aβ production related protein BACE1 in the brain of the high-dose group of Bajijiasu was significantly decreased(P<0.05).Compared with the model group,the protein levels of NEP and IDE were significantly increased in the brain of the high-dose group of Bajijiasu(P<0.01,P<0.01).ELISA test results showed that compared with the model group,the level of A β 1-42 in the brain of the high-dose group of Bajijiasu was significantly decreased(P<0.01).The results of thioflavin-S staining showed that the number of senile plaques in the high-dose group of Bajijiasu was significantly decreased compared with the model group(P<0.01).3.Effects of Bajijiasu on the expression of neurotrophic factors in the brain of APP/PS1 double transgenic miceWestern Blot analysis showed that the levels of neurotrophic factors BDNF and NGF were increased in the high-dose group of Bajijiasu compared with the model group(P<0.05,P<0.01).4.Effects of Bajijiasu on the expression of neuroinflammatory factors in the brain of APP/PS1 double transgenic mice brainThe Western Blot results showed that compared with the model group,the expression of NF-κ B in the brain of the high-dose group of Bajijiasu was significantly lower than the model group(P<0.01).Compared with the model group,the expression of TNF-α and IL-1β were significantly decreased in the high-dose group of Bajijiasu(P<0.01,P<0.01).5.Effect of Bajijiasu on synaptic structure stability in the brain of APP/PS1 double transgenic miceThe Western Blot results showed that compared with the model group,the levels of synaptic structure-related proteins SYN,PSD-93,PSD-95 were significantly increased in the high-dose group of Bajijiasu(P<0.05,P<0.01,P<0.05).ConclusionThe experiment results of behavioral tests showed that Bajijiasu could improve the learning and memory abilities of APP/PS1 double transgenic mice.Biochemical analysis and morphological results showed that Bajijiasu may play a neuroprotective role by regulating the metabolism of Aβ,neurotrophic factors level,neuroinflammatory factors expression and synaptic structural stability in APP/PS1 double transgenic mice.Bajijiasu is expected to bring new treatment strategies to the treatment of degenerative diseases of the central nervous system.However,the more in-depth mechanism remains to be further explored. |
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