As the main water channel expressed in the brain,aquaporin 4(AQP4)has been implicated in the pathological process of ischemic stroke.After ischemic stroke,the expression,phosphorylation and polarity distribution of AQP4 are affected by the process of transcription and post-translational modification.The paper summarized the basic structure,physiological function,dynamic expression changes and mechanisms of AQP4 in this review,specifically discussing the role of AQP4 in cerebral edema,blood-brain barrier permeability and neuroinflammation after ischemic stroke,offering an up-to-date perspective on further effective therapeutic strategies for ischemic stroke.

Objective To explore the effects of M1 polarization of microglia on secondary damage in the thalamus after cerebral cortical infarction.Methods A focal cortical infarct model of adult male SD rats was pre-pared using eletrocoagulation and randomized into Sham and model groups at different time points 1～4 weeks after surgery.Based on the assessment of neurofunctional changes in each group of rats,immunohistochemistry was used to observe the number and morphology of NeuN,GFAP and Iba-1 positive cells in(Ventral posterior nucleus of thalamus,VPN)of the ipsilateral thalamus after distal middle cerebral artery occlusion(dMCAO).Immunofures-cence was used to detect the number and morphology of M1 microglia marker(Iba-1+/CD68+cells)and M2 microg-lia marker(Iba-1+/CD206+cells)in VPN of the ipsilateral thalamus after dMCAO.Western blot was used to detect the expression levels of IL-1β,TNF-α,IL-10 and Arg-1 in VPN of the ipsilateral thalamus after dMCAO.Results The results of immunohistochemistry showed a significant decrease in NeuN positive cells and an increase in the density of GFAP and Iba-1 in the ipsilateral VPN of rats after dMCAO when compared with Sham group(P<0.001).Compared with sham group,the protein levels of TNF α and IL-1β were elevated in the ipsilateral VPN elevated(P<0.05).In addition,the model group rats exhibited higher Bederson scores,beam-walking test and adhesive removal test scores after dMCAO compared with Sham group(P<0.05).The numbers of M1 microglia marker(Iba-1+/CD68+cells)were significantly increased when compared with M2 microglia marker(Iba-1+/CD206+cells)in ipsilateral VPN of rats after dMCAO.Conclusion M1 polarization of microglia may play an essential role in secondary damage of thalamus after cerebral cortical infarction.

CCAAT/enhancer binding protein β (C/EBPβ), a transcriptional factor of the basic-leucine zipper family, can regulate the transcription activity of downstream target genes. After acute cerebral ischemia, the activity of C/EBPβ changes, and participates in the process of cerebral ischemia injury by regulating neuronal apoptosis and inflammation. This article reviews the molecular biological characteristics of C/EBPβ and its expression changes and role in acute cerebral ischemia, providing a basis for developing new neuroprotective drugs for acute cerebral ischemia using C/EBPβ as therapeutic target.

p75 neurotrophin receptor (p75 NTR) is a member of the tumor necrosis factor receptor superfamily, which interacts with tropomyosin receptor kinase (Trk) receptor or binds neurotrophic factors. It mediates a variety of complex signal transduction pathways, induces synaptic growth and affects cell survival. After acute cerebral ischemia, p75 NTR binds effector factors such as pro-nerve growth factor (proNGF) and sortilin, activating downstream apoptotic signal molecules and leading to neuronal death. Therefore, elucidating the pathways and molecular mechanisms of p75 NTR that mediate neuronal apoptosis in acute cerebral ischemia is of great significance for the development of new therapeutic drugs for acute cerebral ischemia.

In the central nervous system, gap junctions exist between neurons and glial cells. Among them, connexin 43 (Cx43) is one of the most abundant connexin proteins in the central nervous system,involved in the metabolic coupling of intercellular substance exchange and electrical coupling of electrical signaling. It plays an important role in regulating cell metabolism, homeostasis, and cell differentiation. After cerebral ischemia, the uncoupling of gap junctions and abnormal hemichannel activity cause a steady-state imbalance of the internal and external environment of the cells, eventually leading to brain tissue damage.Therefore, maintaining the normal function of Cx43 is essential for protecting brain tissue from neuronal damage induced by cerebral ischemia-reperfusion.