Functional Magnetic Resonance Imaging For Neurobiological Studies In Rats With Chronic Bondage Stress-induced Anxiety-depressive Disorder

BACKGROUND:Chronic restraint is one of the most important factors contributing to anxiety and depression,negatively affecting brain structure and function.It has been shown that by analysing the effects of chronic stress on the neural networks of the brain in a rat model,adaptive changes have been revealed;in particular,abnormal activity in the ST_R&L and MEC_L brain regions as well as alterations in functional connectivity in anxiety-and depression-like behaviours.These findings contribute to the understanding of the effects of chronic stress on the brain and provide new ideas for the treatment of anxiety and depression.Investigating the mechanisms and interrelationships of adaptive changes in the brain can contribute to the development of more effective therapeutic strategies to address mental health problems.OBJECTIVE:Through bio-behavioral studies and functional magnetic resonance imaging(FMRI)analysis,the changes of brain neural network in rats with anxiety and depression disorder caused by chronic stress were observed,and the roles and possible mechanisms of striatum and cerebral cortex in the adaptive changes of rats were investigated.METHODS:Extraction analysis was used to compare the effectiveness of 5 different intervention methods in the rehabilitation of depression and anxiety,to understand the influence of chronic stress on animal behavior,and to identify the degree of anxiety and depression.The changes of resting state functional magnetic resonance imaging,small-world attribute,blood oxygen level dependence,diffusion tensor imaging signal,functional connectivity and other indicators were investigated in the rat model of chronic restraint stress,and the correlation of chronic restraint to anxiety and depression-like behavior and the characteristics of brain small-world network were investigated.By collecting the intersection of ALFF and Reho signals,the DTI scalar was used to verify the changes in the structure and activity of the cross brain region.At the same time,seed-based functional connectivity analysis was used to explore the changes of brain region connectivity in anxiety and depression.RESULTS:1.Meta analysis revealed that the effectiveness of psychological interventions for recovery from anxiety and depression was superior to that of medication(Eketamine),supplements(probiotics),physical activity,and weight management.2.5 consecutive weeks of chronic restraint experimental conditions of 4 hours per day reflected a significant tendency to anxiety in the CRS group through behavioural observations such as the open field experiment,the elevated cross maze experiment,and the forced swimming experiment.3.The small-world network properties of the CRS and Con groups were consistent in the sparsity trend;however,the area under the curve(AUC)of λ-value was significantly lower in the CRS group,while the y-value and σ-value AUC did not change significantly between the CRS group and the control group.In addition,the CRS group had shorter characteristic path lengths(Lp),lower clustering coefficients(Cp)and local efficiencies(Eloc)but higher overall efficiencies(Eglob)in the brain network.4.ALFF signals in the dorsal striatum were increased in rats under conditions of anxiety and depressive disorders;changes in DTI signals in the bilateral striatum were closely associated with anxiety-and depression-like behaviours in rats,confirming and suggesting that the cerebral cortex and the limbic system are the key sites that mediate anxiety-and depression-like behaviours.CONCLUSION:In this study,resting state functional magnetic resonance imaging(FMRI)was used to analyze the changes of brain neural networks.Chronic restraint stress induced unstable and disability-related brain network characteristics,and the information transmission efficiency was low.This study reveals the key role of the striatum and cerebral cortex in stress-induced anxiety and depression.By integrating ALFF and ReHo signals,DTI scalar,and seed-based functional connectivity analysis,we found changes in the structure,activity,and regional consistency of cross brain regions in anxiety and depression states.In particular,changes in DTI signaling in the bilateral striatum were strongly associated with anxiety and depression-like behaviors,while increased ALFF signaling in the dorsal striatum was contrary to the conclusions of previous studies.Seed-based functional connectivity analysis confirmed reduced connectivity between the cortex and striatum and reduced projection of the medial entorhinal cortex and striatum to the whole brain.These results confirm the important role of the striatum and cerebral cortex in anxiety and depression,providing support for further research into the neural circuit mechanisms of these diseases.