| As we all know,Parkinson’s disease(PD)is one of the most important human neurodegenerative diseases.Although it has been studied for a hundred years,the complete molecular-circular pathological mechanism is still unclear.The aggregation of alpha-synuclein(Syn)throughout the onset of PD,and is one of the main pathological features recognized at present.The abnormal aggregation of Syn in different locations in the brain often presents a time-dependent relationship,such as its early appearance in the midbrain and other regions,while its late appearance gradually appears in the motor cortex.However,the current academic community pays more attention to the role of Syn in substantia nigra dopamine degeneration,and there is still a lack of systematic research on how it causes cortical structure and function abnormalities.Clinical anatomy studies have found that the abnormal accumulation of Syn in the motor cortex in the late stage of PD may be related to disease-related movement disorders.Based on the key role of the motor cortex in complex motor learning,this study puts forward a scientific hypothesis: Syn abnormality in the motor cortex aggregation can cause local neural circuit abnormalities and cause PD-related dyskinesia symptoms.To solve the above scientific problems,we used two-photon in vivo calcium imaging,chemical genetics,pharmacological intervention,molecular biology and other methods to construct AAV-SNCA,which overexpressed human Syn,and injected it stereotaxically into the motor cortex of mice.in this PD model,behavioral science,two-photon in vivo calcium imaging technology and electrophysiological technology were combined to detect the structure and function of motor cortex,and then the molecular mechanism was studied by transcriptome sequencing and molecular biology methods,and possible intervention strategies were discussed based on the above results.The results of the study are as follows:(1)By injecting AAV-SNCA into the motor cortex of WT mice to overexpress human Syn,the animals can be induced to develop typical motor learning disorders without affecting other functions such as cognition,emotion and so on.(2)Through the two-photon calcium imaging technology and electrophysiological technology,we found that the motor cortex of the model group mice has excessive excitation of pyramidal neurons,accompanied by a significant decrease in the number of parvalbumin inhibitory interneurons(PV);In this PD model,there is a disorder of cortical excitation-inhibition.(3)Transcriptomics analysis found that the expression level of a proinflammatory factor Lipocalin 2(Lcn2)was significantly increased in the mouse cortex of the model group;and artificially overexpression of Lcn2 in the mouse motor cortex can reproduce PD-like motor learning disorders.At the same time,the neutralization of Lcn2 antibody or the interference of Lcn2 receptor can alleviate the symptoms of PD.This indicates that Lcn2 plays a key role in PD-related cortical circuit defects and motor learning disorders.(4)The microglia cell line BV-2 cultured in vitro showed high expression of Lcn2 after being stimulated with human Syn protein;at the same time,erasing microglia with PLX5622 can significantly reduce the content of Lcn2 and improve motor learning disabilities.This shows that Syn stimulates microglia to secrete Lcn2,which in turn mediates cortical circuit defects and motor learning disorders.In summary,this project established a PD-related dyskinesia model induced by local overexpression of human Syn in the cortex,and explored the mechanism of Syn-mediated motor cortex circuit defects and motor learning disorders,providing a theoretical basis for the in-depth understanding of the pathological mechanism of PD and the development of new clinical treatment strategies. |
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