BACKGROUND:Remyelination in the central nervous system is a basic repair process triggered by demyelinating events,mainly through the proliferation,migration,and differentiation of oligodendrocyte precursor cells into oligodendrocytes.The process of remyelination is affected by many factors such as astrocytes,myelin debris,microglia,macrophages,endothelial cells,pericytes,T cells,and age.OBJECTIVE:Astrocytes play an important role in regulating synaptic activity,nutritional support,and tissue repair in the central nervous system.This review aims to provide potential therapeutic targets for demyelinating diseases of central nervous system by reviewing the role of astrocytes in remyelination.METHODS:A search was conducted on relevant literature collected from CNKI,PubMed,and Web of Science from 2014 tO 2024.The search terms were"astrocytes,oligodendrocyte precursor cells,remyelination"in both Chinese and English.Finally,66 articles were included after screening and summarized.RESULTS AND CONCLUSION:(1)The treatment of demyelinating diseases,such as multiple sclerosis,is limited to disease-modifying therapies,and there is no available method to overcome the failure of remyelination.Therefore,it is necessary to explore targets related to remyelination to promote myelin repair.(2)Remyelination is a process in which oligodendrocyte precursor cells proliferate,migrate,differentiate,and mature into oligodendrocytes,and the latter produce myelin to wrap axons to form myelin sheath.(3)Astrocytes regulate remyelination by phagocytosis of myelin debris,participating in inflammatory response,transforming into oligodendrocyte lineage cells,providing energy supply for oligodendrocyte lineage cells,releasing neurotrophic factors,and secreting extracellular matrix components.(4)The drugs screened in this paper use astrocytes and their derived factors as intervention targets to regulate the remyelination.Some drugs have satisfactory effects,but their effectiveness and safety still need more basic research and clinical trials to verify.(5)The mechanism of action of astrocytes in remyelination has not been fully elucidated,and the related molecular targets and signaling pathways can be further studied.

Objective:To investigate effect and mechanism of hydroxysafflor yellow A(HSYA)activating neuronal autophagy on cerebral ischemia-reperfusion injury through a combination of in vitro and in vivo experiments.Methods:SD rat MCAO/R model was established by improved suture method.Rats were randomly divided into sham surgery(Sham)group,MCAO/R group and MCAO/R+HSYA group,following indicators were detected to determine extent of cerebral ischemia-reperfusion nerve damage:Z-Longa neu-rological function score was detected,TTC staining to measure cerebral infarction area,and TUNEL staining to measure cell apopto-sis;Western blot was used to detect protein expressions of autophagy related markers LC3,Beclin1,P62 and SIRT1 in rat brain tis-sue;immunofluorescence staining was used to observe expression of LC3 co-localization with neurons.OGD/R injury model of SH-SY5Y cells was established and randomly divided into Normal group,OGD/R group,OGD/R+HSYA group,OGD/R+SIRT1 inhibitor(EX-527)group and OGD/R+EX-527+HSYA group.Western blot was used to detect protein expressions of LC3,Beclin1,P62 and SIRT1.Results:Compared with Sham group,model group rats showed impaired neurological function,significantly increased neu-robehavioral scores,widespread cerebral infarction,significantly increased neuronal cell apoptosis,significantly increased autophagy related protein Beclin1 expression and LC3-Ⅱ/LC3-Ⅰ,significantly decreased P62 expression,significantly increased LC3/NeuN co-stained cells,and decreased SIRT1 expression;compared with model group,HSYA intervention group showed a significant decrease in neurological functional scores,a significant reduction in cerebral infarction area,a significant decrease in neuronal cell apoptosis,a further increase in Beclin1 expression and LC3-Ⅱ/LC3-Ⅰ,a further decrease in P62 expression,number of LC3/NeuN and P62/NeuN co-stained cells also increased,and SIRT1 expression significantly increased.Expression trends of Beclin1,LC3-Ⅱ/LC3-Ⅰ,P62 and SIRT1 of cells between normal group,model group and HSYA intervention group were same as animal experiment;compared with model group,expressions of SIRT1,Beclin1 and LC3-Ⅱ/LC3-Ⅰ in OGD/R+EX-527 group were significantly reduced,while expression of P62 was significantly increased;compared with OGD/R+EX-527 group,there was no significant change in SIRT1 expression in OGD/R+EX-527+HSYA group,LC3-Ⅱ/LC3-Ⅰ and Beclin1 expression were significantly increased,and P62 expres-sion was significantly decreased.Conclusion:HSYA can significantly improve neurological deficits in rats after cerebral ischemia-reperfusion,reduce cerebral infarction area,and decrease neuronal cell apoptosis rate,whose neuroprotective effect may be related to its activation of SIRT1,which significantly enhances neuronal autophagy.

BACKGROUND:A large number of studies have shown that neurodegenerative diseases are closely related to oxidative stress injury and the imbalance of mitochondrial dynamics.Lycium barbarum polysaccharides have a neuroprotective effect.However,it is not clear whether lycium barbarum polysaccharides can ameliorate apoptosis induced by oxidative stress injury by regulating abnormal mitochondrial dynamics.OBJECTIVE:To study the effect of lycium barbarum polysaccharides on apoptosis induced by H2O2 in SH-SY5Y human neuroblastoma cells.METHODS:SH-SY5Y cells were cultured in three groups.The control group was cultured for 24 hours.The hydrogen peroxide group was treated with H2O2 for 24 hours,and the lycium barbarum polysaccharide group was treated with lycium barbarum polysaccharide for 2 hours and then treated with H2O2 for 24 hours.After treatment,the levels of malondialdehyde,glutathione,and superoxide dismutase in the precipitation of the cells were detected by kit.Mitochondrial membrane potential was detected by JC-1 kit.Cell viability was detected by MTT assay.Apoptosis was detected by TUNEL.The expression levels of mitochondrial dynamics-related proteins (phosphorylated promoter protein 1,mitochondrial fission protein 1,mitochondrial fusion protein 1,mitochondrial fusion protein 2,and optic atrophy protein 1) and apoptotic proteins (Bax,Bcl-2,and Caspase-3) were detected by immunofluorescence staining and western blot assay.RESULTS AND CONCLUSION:(1) Compared with the control group,the levels of malondialdehyde were increased (P<0.05),and the levels of superoxide dismutase and glutathione were decreased (P<0.05) in the H2O2 group.Compared with the H2O2 group,the malondialdehyde level was decreased (P<0.05),and the superoxide dismutase and glutathione levels were increased (P<0.05) in the lycium barbarum polysaccharide group.(2) The mitochondrial membrane potential in the H2O2 group was lower than that in the control group (P<0.05),and that of lycium barbarum polysaccharide group was higher than that of the H2O2 group (P<0.05).(3) Compared with the control group,the apoptosis rate and the expression of Bax and Caspase-3 protein were increased (P<0.05),while the cell viability and the expression of Bcl-2 protein were decreased (P<0.05) in the H2O2 group.Compared with the H2O2 group,the apoptosis rate and the expression of Bax and Caspase-3 protein were decreased (P<0.05),while the cell viability and the expression of Bcl-2 protein were increased (P<0.05) in the lycium barbarum polysaccharide group.(4) Compared with the control group,the protein expression levels of phosphorylated promoter protein 1 and mitochondrial fission protein 1 were increased (P<0.05),and the protein expression levels of mitochondrial fusion protein 1,mitochondrial fusion protein 2,and optic atrophy protein 1 were decreased (P<0.05) in the H2O2 group.Compared with the H2O2 group,the protein expression levels of phosphorylated promoter protein 1 and mitochondrial fission protein 1 were decreased (P<0.05),and the protein expression levels of mitochondrial fusion protein 1,mitochondrial fusion protein 2,and optic atrophy protein 1 were increased (P<0.05) in the lycium barbarum polysaccharide group.(5) These results indicate that lycium barbarum polysaccharide can improve SH-SY5Y cell apoptosis caused by oxidative stress damage by regulating mitochondrial dynamics.

OBJECTIVE: To observe the effects of electroacupuncture (EA) on improving motor function and regulating microglial activation based on Notch receptor 1 (Notch1)/Hes family bHLH transcription factor 1 (Hes1) pathway in mice with Parkinson's disease (PD). METHODS: Thirty-six male C57BL/6 mice were randomly divided into a control group, a model group and an EA group, 12 mice in each group. PD model was established by intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) for 7 consecutive days in the model group and the EA group. From the 1st day of modeling, EA was applied at "Baihui" (GV20) and bilateral "Shenshu" (BL23) in the EA group, with continuous wave, in frequency of 2 Hz and current of 2 mA, 15 min a time, once a day for 14 days continuously. The behavioral performance was evaluated by gait test, pole climbing test and hanging test, the number of positive cells of tyrosine hydroxylase (TH) and the co-expression positive cells of Notch1/ionized calcium binding adaptor molecule 1 (Iba-1) in the substantia nigra of midbrain was assessed by immunofluorescence, the protein expression of TH, α-synuclein (α-syn), Notch1, Hes1, Iba-1, inducible nitric oxide synthase (iNOS), Arginase-1 (ARG1), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6 and IL-10 was detected by Western blot, the mRNA expression of Notch1 and Hes1 was detected by real-time PCR. RESULTS: Compared with the control group, in the model group, the stride frequency was accelerated (P<0.001) and the stride length was shortened (P<0.001) for the four limbs, the pole climbing test time was prolonged (P<0.01) and the grip level was reduced (P<0.01); in the substantia nigra of midbrain, the number of positive cells of TH was decreased (P<0.001), the number of co-expression positive cells of Notch1/Iba-1 was increased (P<0.001), the protein expression of α-syn, Notch1, Hes1, Iba-1, iNOS, TNF-α, IL-1βand IL-6 was increased (P<0.01, P<0.05, P<0.001), the protein expression of TH, ARG1 and IL-10 was decreased (P<0.01, P<0.001), the mRNA expression of Notch1 and Hes1 was increased (P<0.01). Compared with the model group, in the EA group, the stride frequency was decelerated (P<0.001) and the stride length was increased (P<0.05, P<0.01, P<0.001) for the four limbs, the pole climbing test time was shortened (P<0.05) and the grip level was increased (P<0.05); in the substantia nigra of midbrain, the number of positive cells of TH was increased (P<0.01), the number of co-expression positive cells of Notch1/Iba-1 was decreased (P<0.001), the protein expression of α-syn, Notch1, Hes1, Iba-1, iNOS, TNF-α, IL-6 and IL-1β was decreased (P<0.05, P<0.01), the protein expression of TH, ARG1 and IL-10 was increased (P<0.05, P<0.001, P<0.01), the mRNA expression of Notch1 and Hes1 was decreased (P<0.05). CONCLUSION EA can improve the behavioral performance and protect the dopaminergic neurons in PD mice, its mechanism may relate to the inhibition of Notch1/Hes1-mediated neuroinflammation, thus inhibiting the microglial activation.
Animals ; Electroacupuncture ; Microglia/metabolism* ; Male ; Receptor, Notch1/metabolism* ; Parkinson Disease/physiopathology* ; Transcription Factor HES-1/metabolism* ; Mice ; Mice, Inbred C57BL ; Humans ; Signal Transduction

BACKGROUND:In the occurrence and development of demyelinating diseases of the central nervous system,neuroinflammation caused by microglia is the main pathological feature,so inhibiting the inflammatory response is very important to alleviate demyelination.Hydroxysafflor yellow A can protect the blood-brain barrier,inhibit neuronal apoptosis,and improve neurological function.OBJECTIVE:To explore the mechanism of hydroxysafflor yellow A inhibiting bicyclohexanone oxalyl dihydrazone-induced demyelination in mice.METHODS:(1)In vivo:Thirty healthy male C57BL/6 mice were randomly divided into three groups:normal group,cuprizone group,and hydroxysafflor yellow A group.The mice in the cuprizone group and the hydroxysafflor yellow A group were fed with 0.2％cuprizone diet for 6 weeks to establish mouse models of demyelination.The mice in the normal group were fed with normal diet.At the end of the 4th week,the mice in the hydroxysafflor yellow A group were intraperitoneally injected with hydroxysafflor yellow A 20 mg/kg per day.The mice in the normal and cuprizone groups were intraperitoneally injected with normal saline for 2 weeks.The behavioral changes of mice were evaluated by open field test and elevated plus maze test.The loss of myelin sheath in corpus callosum was detected by black gold staining,myelin basic protein and degraded myelin basic protein immunofluorescence staining.The activation of microglia and the expression of inflammatory factors were detected by I ba-1 immunofluorescence staining and ELISA,respectively.The protein expression levels of Toll-like receptor 4,myeloid differentiation factor 88,and nuclear factor κB p65 in the brain of mice in each group were detected by western blot assay.(2)In vitro experiment:The inflammation model of BV2 microglia was established by lipopolysaccharide induction.BV2 cells were divided into normal group,lipopolysaccharide group(1 μg/mL),and lipopolysaccharide(1 μg/mL)+hydroxysafflor yellow A(25 μmol/L)group.The expression levels of tumor necrosis factor α and interleukin 6 in the supernatant were detected by ELISA.RESULTS AND CONCLUSION:(1)Compared with the normal group,the mice in the cuprizone group had severe anxiety,abnormal autonomic movement ability,and a large amount of myelin sheath loss in the corpus callosum.The average fluorescence intensity of myelin basic protein was significantly reduced,and the average fluorescence intensity of degraded myelin basic protein was significantly increased.The number of lba1+microglia increased,the contents of interleukin 1β,tumor necrosis factor α,and interleukin 6 in the brain increased,and the protein expression levels of Toll-like receptor 4,myeloid differentiation factor 88,and nuclear factor κB p65 increased significantly.The above symptoms and indexes of mice were reversed after hydroxysafflor yellow A treatment.(2)Hydroxysafflor yellow A significantly inhibited the expression of inflammatory factors such as tumor necrosis factor α,and interleukin 6 induced by lipopolysaccharide in BV2 microglia.(3)The above results demonstrate that hydroxysafflor yellow A can significantly improve cuprizone-induced demyelination in mice.The mechanism of action is related to the inhibition of microglial activation-mediated inflammatory response through the Toll-like receptor 4/myeloid differentiation factor 88/nuclear factor κB p65 signaling pathway.

BACKGROUND:Neurodegenerative diseases are closely related to the imbalance of mitochondrial autophagy regulation.Previous studies by the research group have shown that lycium barbarum polysaccharide has neuroprotective effects,but whether it can improve the damage of SH-SY5Y cells induced byβ-amyloid protein 1-42 by regulating mitochondrial autophagy is still unclear.OBJECTIVE:To explore the protective effect and mechanism of Lycium barbarum polysaccharide on SH-SY5Y cells induced by β-amyloid protein 1-42.METHODS:An Alzheimer's disease cell model was established by inducing SH-SY5Y cells with β-amyloid protein 1-42,and then intervening with Lycium barbarum polysaccharide.SH-SY5Y cells were divided into three groups:control group,β-amyloid protein 1-42 group(20 μmol/L β-amyloid protein 1-42 for 24 hours),and Lycium barbarum polysaccharide group(1 g/L Lycium barbarum polysaccharide was added 1 hour in advance to form a protective effect,and then 20 μmol/L β-amyloid protein 1-42 was added to intervene with Lycium barbarum polysaccharide for 24 hours).CCK8 assay was used to detect cell viability.Mitochondrial membrane potential was detected by JC-1.TUNEL staining was used to detect cell apoptosis.Immunofluorescence and western blot assay were used to detect the expression of synaptic,apoptosis,and mitophagy-related indicators.RESULTS AND CONCLUSION:(1)Compared with the control group,the cell viability of the β-amyloid protein 1-42 group decreased(P＜0.05);cell apoptosis rate increased(P＜0.05);mitochondrial membrane potential decreased(P＜0.05);the expressions of pro-apoptotic proteins Bax and Caspase3 increased(P＜0.05);the expression of anti-apoptotic protein Bcl-2 decreased(P＜0.05);the expression levels of synaptic-related proteins Syn and PSD-95 decreased(P＜0.05);the expression levels of mitochondrial autophagy-related proteins Pink1,LC3A/B,Parkin,and Beclin-1 decreased(P＜0.05);and the expression of P62 increased(P＜0.05).(2)Compared with the β-amyloid protein 1-42 group,the cell viability in the Lycium barbarum polysaccharide group was increased(P＜0.05);the apoptosis rate was decreased(P＜0.05);the mitochondrial membrane potential was increased(P＜0.05);the expression levels of Bax and Caspase3 were decreased(P＜0.05);the expression of Bcl-2 was increased(P＜0.05);the expressions of Syn and PSD-95 were increased(P＜0.05);the expression levels of Pink1,LC3A/B,Parkin,and Beclin-1 were increased(P＜0.05),and the expression of P62 was decreased(P＜0.05).These findings indicate that Lycium barbarum polysaccharide may inhibit β-amyloid protein 1-42-induced damage to SH-SY5Y cells by regulating mitophagy,reduce cell apoptosis,and increase neuronal synaptic plasticity.

Objective:To investigate the neuroprotective effect of nicotinamide riboside(NR)on experimental autoimmune en-cephalomyelitis(EAE)mice.Methods:C57BL/6 female mice were induced by myelin oligodendrocyte glycoprotein(MOG35-55)to pro-duce EAE model and were randomly divided into EAE group and NR group.From day 3 to day 27 after immunization,each mouse in EAE group was given normal saline(200 μl/d)and each mouse in NR group was given NR(500 mg/kg,200 μl/d)by intragastric administration.Clinical score and body weight of mice in EAE group and NR group were recorded every day.On the 28th day after immunization,the spinal cord protein of mice in each group was extracted and the frozen sections of spinal cord of mice in each group were prepared.LFB staining was used to detect demyelination,immunofluorescence staining was used to detect the expression of MAP-2 and the number of positive cells of NeuN,BDNF,GDNF,NGF and NT-3,and Western blot was used to detect the expressions of BDNF,GDNF,NGF and NT-3 of spinal cord.Results:Compared with EAE group,NR significantly delayed the onset time of EAE mice(P<0.05),decreased clinical score(P<0.05),reduced weight loss,alleviated spinal cord demyelination(P<0.05),increased the expression of MAP-2(P<0.01)and the number of NeuN positive cells(P<0.01),and up-regulated the expressions of BDNF,GDNF,NGF and NT-3(P<0.05).Conclusion:NR shows a good neuroprotective effect on EAE mice.The mechanism may be related to NR significantly increasing the expression of spinal neurotrophic factors,improving the microenvironment of the central nervous sys-tem,nourishing nerves,promoting nerve repair and nerve growth,etc.

Objective:To investigate the effect of ginkgolide B(GB)on astrocyte(AST)phagocytosis of myelin debris,and to investigate the mechanism of this functional therapy to demyelination by targeting AST.Methods:In vitro culture of AST,and divided AST into three groups:Control group,Myelin debris(Debris)group and Debris+GB group,incubed them in a constant temperature CO2 cell culture incubator for 24 hours,and then detected relevant indicators to observe the effect of GB on AST on phagocytic myelin debris.Results:Compared to the phagocytosis of myelin debris by primary AST,GB could effectively promote the phagocytosis by AST and show enhanced ABCA-1 expression(both P<0.05).Phagocytosis of myelin debris had no effect on the secretion of inflammatory cytokines by in vitro cultured AST.Debris+GB increased the expressions of neurotrophic CNTF and B-FGF compared to Debris(both P<0.05).Furthermore,Debris+GB decreased Bax and Caspase-3,while increased Bcl-2 expression(all P<0.05).Conclusion:GB can promote the phagocytosis of myelin debris by AST,which may be related to the upregulation of ABCA-1.Meanwhile,phagocytosis of myelin debris by AST increases the expression of the neurotrophic factors and the inhibits the apoptosis of AST themselves.

Neurodegenerative diseases are a group of chronic progressive diseases characterized by inflammation,degenera-tion and apoptosis.Chronic neuroinflammation is gradually becoming a potential pathogenic and predisposing factor.As a widely expressed non-histone nucleoprotein,HMGB1 participates in inflammatory process of human body through receptors of advanced glycation end products and Toll-like receptors while maintaining chromosome homeostasis.As a key factor of neuroinflammation,HMGB1 is widely involved in development of neurodegenerative diseases and may become a biomarker and a potential therapeutic target of neurodegenerative diseases.This article reviews the role of HMGB1 in neurodegenerative diseases and tries to provide ground-work for basic research and clinical application for targeting HMGB1 in the treatment of neurodegenerative diseases.

Objective:To explore effects and mechanism of Hydroxylsafflower Yellow A(HSYA)on expression of NLRP3 in glial cells after cerebral ischemic injury.Methods:A middle cerebral artery occlusion/reperfusion(MCAO/R)model was established in male SD rats.After successfully modeling for 24 h,Longa scoring and corner test were used to evaluate degree of neurological dys-function.Western blot and immunofluorescence were used to detect expressions of JAK2/STAT3 molecules and NLRP3,ELISA was used to measure IL-1β,IL-6 and TNF-α levels.A glucose-oxygen deprivation/reperfusion(OGD/R)model was established in microg-lia,and JAK2 and STAT3 inhibitor AG490 was used to further verify action of HSYA on NLRP3.Results:Compared with sham group,neurological dysfunction aggravated in MCAO/R group(P<0.01),HSYA treatment improved neurological function(P<0.01).Expres-sions of p-JAK2,p-STAT3 and NLRP3 in MCAO/R group were higher than those in the sham group(P<0.01);and HSYA treatment reduced expressions of p-JAK2,p-STAT3 and NLRP3(P<0.01).Levels of inflammatory factors IL-1β,IL-6 and TNF-α were higher in MCAO/R group than sham group(P<0.01),and HSYA inhibited expressions of IL-1β,IL-6 and TNF-α(P<0.01 or P<0.05).In vi-tro experiments showed expressions of p-JAK2,p-STAT3 and NLRP3 in OGD/R group were significantly higher than normal control group(P<0.01),after adding AG490,phosphorylation of JAK2 and STAT3 decreased,NLRP3 expression was inhibited(P<0.01).Inflammatory cytokines IL-1β,IL-6 and TNF-α levels were higher in OGD/R group than normal control group(P<0.01),and HSYA inhibited expressions of IL-1β,IL-6 and TNF-α(P<0.01 or P<0.05).Conclusion:HSYA alleviates brain damage,probably by regu-lating JAK2/STAT3 signaling pathway and inhibiting NLRP3 expression in microglia after cerebral ischemia and hypoxia.