| ObjectiveCognitive impairment is the main early symptom of Alzheimer’s disease(AD),and stress injury is an important risk factor that induces cognitive impairment and then develops into AD.Therefore,research on how stress injury can induce cognitive impairment and whether intervention of cognitive impairment induced by stress injury can delay or prevent the occurrence of AD has become the focus.In this study,serum metabolomics was used to investigate how chronic stress can induce cognitive impairment,and to explore the role and mechanism of Radix Bupleuri-Radix Paeoniae Alba pairs on intervention of chronic stressinduced cognitive impairment to prevent AD.MethodsThe chronic unpredictable mild stress(CUMS)modeling method was used to conduct sucrose preference test,open field test,Morris water maze test at 14,28,42,56,and 70 days after modeling.Animals were sacrificed 70 days after modeling,serum and hippocampus were tak en,LC-MS was used to detect differential metabolites in serum,Western Blot was used to detect the protein expression levels of synaptic plasticity protein synaptophysin(SYN)and post-synaptic dense protein 95(PSD-95),and the protein expression levels of cholesterol homeostasis-related proteins apolipoprotein E(ApoE)and ABC A transporter 1(ABCA1).An animal model of CUMS was established,and on the 42nd day after modeling,the animals were randomly divided into CUMS group(Model),CUMS+positive drug group(Fluoxetine),and CUMS+Radix Bupleuri-Radix Paeoniae Alba pairs to low dose group(CB-Low),CUMS+Radix Bupleuri-Radix Paeoniae Alba pairs to high-dose group(CBHigh),and the control group(Control)without modeling,a total of 5 groups,8 in each group.The positive drug was administered with fluoxetine by gavage at 5mg/(kg·d);The Radix Bupleuri-Radix Paeoniae Alba pairs was administered at a low dose of 3 g/(kg·d)and a high dose of 9 g/(kg·d)for 28 days.On the 70th day after modeling,new object recognition test and passive avoidance test were performed;serum was taken and LC-MS was used to detect serum differential metabolites;hippocampus was taken and Western Blot was used to detect the protein expression levels of PSD-95,SYN and nerve growth associated proteins 43(GAP43),ApoE and ABCA1,phosphorylation of AMP-dependent protein kinase(AMPK)and acetyl-CoA carboxylase(ACC),the protein expression levels of sterol-regulatory element binding proteins 1(SREBP1),fatty acid synthase(FASN),and Lipin1.The number of neurons in hippocampal CA1 area was detected by Nissl staining.ResultsFrom the 14th day of CUMS modeling,compared with the control group,the weight gain of the model group was significantly decreased(P<0.05).After 42 days of modeling,compared with the control group,the sucrose preference rate of the model group decreased(P<0.05),and the central area time and central area distance of the model group decreased(P<0.05).On the 70th day of modeling,compared with the control group,the weight gain,sucrose preference rate,central area time and central area distance of model rats all significantly decreased(P<0.05),the latency of the place navigation experiment increased and the number of crossing platforms in the spatial probe experiment decreased(P<0.05).The protein expression levels of PSD-95 and SYN decreased,and the protein expression level of ApoE was significantly decreased(P<0.05),and the protein expression level of ABCA1 was significantly increased(P<0.05).The results of serum metabolism experiments showed that compared with the control group,the majority of differential metabolites in the serum of model rats were lipids,the most relevant enrichment pathway is also related to lipid metabolism.These results suggest that CUMS can lead to the process of depression to cognitive impairment of rats,inhibit synaptic plasticity in the hippocampus of rats,leading to disturbance of lipid metabolism of rats.The results of the drug intervention experiment showed that compared with the model group,Radix Bupleuri-Radix Paeoniae Alba pairs increased the weight gain of the high-dose group(P<0.05),the discrimination ratio of new object recognition test increased significantly(P<0.05),and the latency of passive avoidance test was significantly increased(P<0.05),the protein expression levels of PSD-95,SYN and GAP43 were increased(P<0.05),the number of neurons in hippocampal CA1 area also increased in Nissl staining(P<0.05).These results showed that Radix Bupleuri-Radix Paeoniae Alba pairs could improve CUMS-induced cognitive impairment of rats,improve synaptic plasticity and protect neurons.Further research results showed that compared with the model group,the Radix Bupleuri-Radix Paeoniae Alba pairs significantly decreased the levels of serum lipid metabolites of the model rats(P<0.05),and the protein expression level of ApoE in the hippocampus increased significantly(P<0.05),the protein expression level of ABCA1 decreased.The phosphorylation levels of AMPK and ACC increased(P<0.05),and the protein expression levels of SREBP1,FASN,and Lipin1 decreased(P<0.05).It shows that the Radix Bupleuri-Radix Paeoniae Alba pairs can down-regulate ABCA1 protein expression,up-regulate ApoE protein expression,activate phosphorylation of AMPK,increase the phosphorylation level of ACC,down-regulate the protein expression levels of SREBP1,FASN and Lipin1,regulate lipid metabolism and enhance synaptic plasticity to protect neurons and improve cognitive impairment.Conclusion1.Chronic stress can cause the imbalance of cholesterol homeostasis in the hippocampus of model animals,leading to disturbances in lipid metabolism and thus cognitive impairment.2.Radix Bupleuri-Radix Paeoniae Alba pairs can prevent chronic stress-induced cognitive impairment,and its mechanism may be through down-regulating the protein expression of cholesterol homeostasis protein ABCA1,up-regulating the protein expression of ApoE,activating the phosphorylation of AMPK,and enhancing the phosphorylation of ACC,down-regulate the protein expression levels of SREBP1,FASN and Lipin 1 to regulate lipid metabolism,thereby improving synaptic plasticity,protecting neurons,and improving cognitive impairment. |
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