MRNA And Micro Rna Profiles In The Medial Prefrontal Cortex Are Associated With Stress Susceptibility And Resilience Induced By Psychological Stress

Background: Severe or excessive stress can induce phobia,anxiety,depression,and posttraumatic stress disorder.People’s responses to stress and trauma vary widely.Some people develop related mental illnesses,while most people who experience stressful events do not show signs of mental illness,such as posttraumatic stress disorder or depression.But the molecular mechanisms that mediate these resistance to stress remain unclear.The medial prefrontal cortex(m PFC)is associated with many mental neurological diseases.There are relatively few studies on molecular expression profiles in the medial prefrontal cortex.The m RNA and micro RNA profiles of stress susceptibility and resilience induced by psychological stress in the medial prefrontal cortex remain to be elucidated.By analyzing the expression profiles of m RNA and mi RNA in the prefrontal cortex,it is possible to find molecules related to stress susceptibility and resilience,which is of great significance for developing relevant therapeutic targets and formulating therapeutic strategies.Materials and Methods: Fear memory and anxiety in mice were induced by a witness paradigm adjusted by the social defeat paradigm.The C57 observer was placed in the room neighboring to the room of CD1 mouse and suffered psychological stress by watching the CD1 attacking another C57 mouse.After five days of psychological stress,the mice’s levels of fear memory and anxiety were measured by social interaction test and elevated plusmaze(EPM).The observer group was divided into susceptible group and resilient group based on the results of behavioral experiments.High-throughput sequencing was used to analyze m RNA and micro RNA profiles in the medial prefrontal cortex harvested from control,resilient,susceptible mice.Bioinformatics analysis was performed on the sequencing results,and micro RNA and m RNA differentially expressed in the control group,the resilient group and the susceptible group were screened with the difference multiple of more than twice as the standard.We used RNAhybrid,Targetscan,and mi Randa for target gene prediction.Micro RNA and m RNA regulatory networks were constructed by using cytoscape software.We selected a part of m RNA and micro RNA for quantitative RT-PCR and validated the accuracy of target gene prediction by dual-luciferase reporter assay.Results: In the social interaction test,there was no statistical difference between the control group,the resilient group and the susceptible group at day0.At day6,the ratio in the susceptible group significantly decreased compared with the control group and the resilient group.In the elevated plus-maze(EPM),there was no statistical difference between the control group,the resilient group and the susceptible group at day0.At day6,the open arm time ratio of the susceptible group was significantly decreased compared with the control group and the resilient group.These results suggest that stress susceptibility or resilience were developed through five days of psychological stress in mice.By comparing differentially expressed genes,the down-regulated genes involved in serotonergic synapse may be related to the susceptibility to psychological stress in susceptible mice versus resilient mice.The imbalanced regulation of genes involved in VEGF,p53,Chemokine,Ras,Sphingolipid,Gn RH,MAPK,and NOD-like receptor signaling pathways may be related to the susceptibility to psychological stress.Compared with control mice,genes involved in the serotonergic synapse,neuroactive ligand-receptor interaction,axon guidance,calcium,c AMP,Gn RH,Estrogen,PI3K-Akt,MAPK,Rap1,Ras signaling pathways were changed in both susceptible mice and resilient mice.These changes may be related to psychological stress processing.The sequencing results of m RNA and micro RNA were verified by q RT-PCR and dual-luciferase reporter assay.Conclusion: The down-regulation of genes involved in serotonergic synapse and imbalance of signaling pathways in the medial prefrontal cortex may be related to susceptibility to psychological stress.The increased expressions of genes in certain specific signaling pathways and the decreased expressions of other genes in these pathways indicate an imbalance in the regulation of each signaling pathway.A variety of signaling pathways and the up-regulation and down-regulation of genes in the signaling pathways cause an imbalance in the molecular networks of the medial prefrontal cortex,leading to abnormal neuronal and synaptic functions in the medial prefrontal cortex,which can cause stress susceptibility or resilience.