The secondary damage after traumatic brain injury (TBI) involves a variety of pathological processes, and the inflammatory response in the nervous system is an important factor which affects nerve repair and regeneration. As the innate immune cell in the nervous system, microglia (MG) plays an important role in the entire neuroinflammatory environment by regulating the activation state of MG and changing the inflammatory response in the direction of promoting nerve repair and regeneration, which has great potential in treatment of TBI. This article reviews the inflammatory response of the nervous system after TBI and the reactivity of MG, as well as their significance in nerve repair and regeneration.

Objective:To explore the effects of dopamine receptor D2(DRD2)on astrocytic dedifferentiation based on SOX2-regulated genes in neural stem cells(NSCs)and astrocytes.Methods:Immunofluorescence staining and SOX2-GFP mice were used to examine the lineage differentiation of SOX2-positive cells during the development of cere-bral cortex.Primary NSCs/astrocytes culture,ChIP-seq and Western Blot were adopted to analyze and verify the expres-sion of candidate genes.Pharmacological manipulation,neurosphere formation,photochemical ischemia,immunofluo-rescence staining and behavior tests were adopted to evaluate the effects of activating DRD2 signaling on astrocytic dedif-ferentiation.Results:Immunofluorescence staining demonstrated the NSC-astrocyte switch of SOX2-expression in the normal development of cerebral cortex.ChIP-seq revealed enrichment of DRD2 signaling by SOX2-bound enhancers in NSCs and SOX2-bound promoters in astrocytes.Western Blot and immunofluorescence staining verified the expression of DRD2 in NSCs and reactive astrocytes.Application of quinagolide hydrocholoride(QH),an agonist of DRD2,signifi-cantly promoted astrocytic dedifferentiation both in vitro and in vivo following ischemia.In addition,quinagolide hydro-choloride treatment improved locomotion recovery.Conclusion:Activating DRD2 signaling facilitates astrocytic dedif-ferentiation and may be used to treat ischemic stroke.