Multi-omics Analysis Of The Amygdala In A Rat Chronic Unpredictable Mild Stress Model Of Depression

BackgroundMajor depressive disorder(MDD)is a mental illness that interacts with genes and the environment.The main clinical features are significant and lasting depression and decreased interest.The incidence and recurrence rate of depression and the risk of suicide are extremely high,which imposes a serious burden on people’s physical and mental health and social economy.As the pace of life accelerates and competitive pressure increases,the incidence of depression is increasing year by year.The World Health Organization(WHO)reports that more than 320 million people worldwide suffer from depression.As of 2017,there are more than 54 million people suffering from depression in China.In China,depression has become the second most serious disease after heart disease,with about 1/7 adults suffering from depression.Therefore,the research on the pathogenesis of depression and the research and development of antidepressants are imminent.Depression is a mental illness with multiple pathogenesis and large heterogeneity.The pathogenesis is unclear and complex,and is accompanied by a large number of abnormal changes in molecules and pathways.Stress is an important factor that induces the onset of depression,and chronic and long-term stress events can lead to long-term psychological stress.The mechanism of the chronic unpredictable mild stress(CUMS)depression model is closer to the pathogenesis of human depression.The CUMS model is durable,stable and highly effective.It is an ideal and reliable animal model for depression and the most commonly used animal model for depression research.In recent years,multi-omics methods have been widely used in the study of molecular mechanisms of various diseases.It not only promotes the study of disease mechanisms and the identification of pathogenic targets,but also provides new ideas for basic disease science and precision medicine research.Therefore,multi-omics integrated analysis has become a new direction to explore the pathogenesis of depression,and proteomic and metabolomic integrated analysis is one of the most effective and commonly used methods.In this study,we focused on amygdala,a key brain area involved in emotion regulation and stress response.Furthermore,we applied an integrated analysis of proteomic and metabolomic data in chronic unpredictable mild stress(CUMS)rat model to explore the molecular mechanism of depression,which will provide the theoretical basis for seeking new antidepressant drug targets for clinical treatment.ObjectiveTo identify differential proteins and metabolites in amygdala in the CUMS model and the corresponding control groups.By applying integrated analysis of proteomic and metabolomic data in CUMS rat model,we aim to further investigate the pathogenesis of depression and provide potential targets for antidepressant drugs.Method1.We established the CUMS model and the corresponding control group,and selected stress-susceptible rats through the sucrose preference test(SPT).SPT and forced swim test(FST)were conducted to assess depressive-like behavior,and open field test(OFT)and elevated plus-maze(EPM)were performed to evaluate anxiety-like behavior.2.We conducted liquid chromatography-tandem mass spectrometry(LC-MS/MS)technology to detect the metabolite profiles of the amygdala of the CUMS and control rats.Metabo Analyst was used to conduct pathway enrichment analysis of differential metabolites in the CUMS model.3.We conducted isobaric tags for relative and absolute quantitation(iTRAQ)proteomic technology to detect the protein profiles of the amygdala of the CUMS and control rats,and identified differential expressed proteins.Then Ingenuity Pathway Analysis(IPA)was used to conduct integrated analysis of the differential metabolites and proteins of the CUMS model.Results1.The weight gain of CUMS rats was significantly decreased;there were significant differences in depression-like behavior test,which were reflected in a significant decrease in SPT and increase in immobility time of FST.There were no significant differences in anxiety-like behavior test,which was reflected in the total distance,central activity,or rearing frequency in the OFT and in the total number of entries or the time spent in the open and closed arms between the two groups in the EPM compared with the control group.2.In the proteomic,CUMS rats identified 171 significant changed proteins.Of these,112 proteins were upregulated and 59 were downregulated compared with the control group.In the metabonomic results,CUMS rats identified 42 significant changed.Of these,11 metabolites were upregulated and 31 were downregulated compared with the control group.3.The proteomic and metabonomic integration analysis found:(1)amino acids,carbohydrate metabolism and their transport-/catabolism-related proteins,and metabolic enzyme perturbations;(2)abnormal expression of synaptogenesis and oxidative phosphorylation-associated proteins.ConclusionIn the present study,our LC-MS/MS-based metabolomic and iTRAQ-based proteomic results provide a comprehensive understanding of the molecular changes that occur in the amygdala of CUMS rats.There were some consistent changes between metabolomics and proteomics in the CUMS model rats,including the dysregulation of amino acid metabolism,glucose metabolism,synaptic signaling,and oxidative phosphorylation-associated proteins.These findings provide further insights into the pathogenesis of depression and may help to identify potential targets for antidepressants.