The Effect Of Netrin-1 On Microglia Development

Microglia are macrophages in the central nervous system,which play a crucial role in the ontogenesis and homeostasis regulation of the adult brain.Dysplasia and dysfunction of microglia are closely related to neurodevelopmental diseases and neuropsychiatric diseases.Through this study,we hope to reveal the role of Netrin-1 in the development of microglia.In this study,we used Western Blotting to detect the expression of Netrin-1 in the cortex at different development stages.It was found that the expression of Netrin-1 was higher during embryonic to postnatal P7,but decreased significantly during P14 to adulthood.The body weight,body length,brain size,brain weight and the corpus callosum were normal.Immunofluorescent staining was used to further analyze the number and morphology of microglia in the cortex.The morphology results showed that cell bodies became larger and branches became shorter of microglia,compared with wild type mice at P14 stage,but there was no significant difference in the number of microglia in cortex.In addition,statistical results showed that the number of endpoints and lengths of process in microglia decreased significantly at P14 mutant.In the P30 mutant mice,the number of endpoints and lengths of process in microglia are slightly larger than wild type mice.The morphology of microglia returned to normal at adulthood(P56).The above results suggest that the deletion of Netrin-1 leads to microglial abnormalities at certain stages of development.Using Fluorescence Quantitative PCR detected the inflammatory factors in the cortex of Netrin-1^f/f;GFAP-cre mice,the results show that the m RNA expression levels of IL-1 and TNF-?are increased significantly compared with wild type mice.Behavioral experiments showed that Netrin-1^f/f;GFAP-cre mice did not exhibit abnormal behaviors such as anxiety,depression.In summary,the deletion of Netrin-1 affected the morphological development of postnatal mouse microglia at P14-P30 stage,producing an activated phenotype accompanied by increased expression of IL-1 and TNF-?.