GPCR-Gs mediates the protective effects of ginsenoside Rb1 against oxygen-glucose deprivation/re-oxygenation-induced astrocyte injury

Objectives:To investigate whether the protective actions of ginsenoside Rb1(Rb1)on astrocytes are mediated through the G_(s)-type G-protein-coupled receptor(GPCR-G_(s)).Methods:Primary astrocyte cultures derived from neonatal mouse brain were used.Astrocyte injury was induced via oxygen-glucose deprivation/re-oxygenation(OGD/R).Cell morphology,viability,lactate dehydrogenase(LDH)leakage,apoptosis,glutamate uptake,and brain-derived neurotrophic factor(BDNF)secretion were assessed to gauge cell survival and functionality.Western blot was used to investigate the cyclic adenosine monophosphate(cAMP)and protein kinase B(Akt)signaling pathways.GPCR-G_(s)-specific inhibitors and molecular docking were used to identify target receptors.Results:Rb1 at concentrations ranging from 0.8 to 5μM did not significantly affect the viability,glutamate uptake,or BDNF secretion in normal astrocytes.OGD/R reduced astrocyte viability,increasing their LDH leakage and apoptosis rate.It also decreased glutamate uptake and BDNF secretion by these cells.Rb1 had protective effects of astrocytes challenged by OGD/R,by improving viability,reducing apoptosis,and enhancing glutamate uptake and BDNF secretion.Additionally,Rb1 activated the cAMP and Akt pathways in these cells.When the GPCR-G_(s) inhibitor NF449 was introduced,the protective effects of Rb1 completely disappeared,and its activation of cAMP and Akt signaling pathways was significantly inhibited.Conclusion:Rb1 protects against astrocytes from OGD/R-induced injury through GPCR-G_(s) mediation.

Lactoferrin modification of berberine nanoliposomes enhances the neuroprotective effects in a mouse model of Alzheimer’s disease

Previous studies have shown that berberine has neuroprotective effects against Alzheimer’s disease,including antagonizing tau phosphorylation,and inhibiting acetylcholinesterase activity and neural cell apoptosis.However,its low bioavailability and adverse reactions with conventional administration limit its clinical application.In this study,we prepared berberine nanoliposomes using liposomes characterized by low toxicity,high entrapment efficiency,and biodegradability,and modified them with lactoferrin.Lactoferrin-modified berberine nanoliposomes had uniform particle size and high entrapment efficiency.We used the lactoferrin-modified berberine nanoliposomes to treat a mouse model of Alzheimer’s disease established by injection of amyloid-beta 1-42 into the lateral ventricle.Lactoferrin-modified berberine nanoliposomes inhibited acetylcholinesterase activity and apoptosis in the hippocampus,reduced tau over-phosphorylation in the cerebral cortex,and improved mouse behavior.These findings suggest that modification with lactoferrin can enhance the neuroprotective effects of berberine nanoliposomes in Alzheimer’s disease.

Neuroprotective Effects of Bushen Decoction Against Glutamate-Induced Neurotoxicity in PC12 Cells

Aim The enhanced effect of Bushen (Kidney-tonifying) decoction (BS) oncultured PC12 cell proliferation and its antagonistic action on neurotoxicity induced by glutamatewere investigated by serum pharmacological method of the Chinese material medica (CMM) in vitro.Methods The effect of BS on cultured PC12 cell activity and its antagonistic action on neurotoxicityinduced by glutamate was observed by MTT method. Flow cytometry and fluorescence microscopetechniques were employed to observe the antagonistic effect of BS on early period apoptosis of PC12cells induced by glutamate. Results The serum with BS was able to enhance activity of PC12 cells andexert antagonistic effect on glutamate-induced neurotoxicity. Meanwhile, these beneficial effectsproduced by BS were found to be the strongest in 20% concentration of in serum BS. Moreover, it caninhibit apoptosis of PC12 cells induced by glutamate , which occurs in the early period. ConclusionBS may exert a potential neuroprotective effect.

Bioactive chemical constituents from the marine-derived fungus Cladosporium sp.DLT-5

A new isochromanone,cladosporinisochromanone(1),accompanied by 15 known compounds(2–16)were obtained from secondary metabolites produced by marine-derived fungus Cladosporium sp.DLT-5.NMR and HRESIMS spectra elucidation determined the planar structure of 1.Subsequent electronic circular dichroism(ECD)experiment assigned the absolute configuration of 1.Compounds 1,2,4–6,and 10 displayed different degrees of neuroprotective activities on human neuroblastoma cells SH-SY5Y.Five compounds(1,3–5,and 13)emerged resistance to protein tyrosine phosphatase 1B(PTP1B),further kinetic analysis and molecular docking study indicated that the most potent compound 13(IC50value of 10.74±0.61μmol/L)was found as a noncompetitive inhibitor for PTP1B.Surface plasmon resonance(SPR)and molecular docking studies also demonstrated the interaction between compound 12 and Niemann-Pick C1 Like 1(NPC1L1),which has been identified as significant therapeutic target for hypercholesteremia.In addition,compounds 3,6,and 14 showed attractive inhibitory activity against the phytopathogenic fungi:Colletotrichum capsici.Therefore,library of Cladosporium metabolites is enriched and new active uses of known compounds are explored.

Pretreatment with Rhodiola Rosea Extract Reduces Cognitive Impairment Induced by Intracerebroventricular Streptozotocin in Rats: Implication of Anti-oxidative and Neuroprotective Effects

Objective To investigate the pretreatment effects of Rhodiola rosea （R. rosea） extract on cognitive dysfunction, oxidative stress in hippocampus and hippocampal neuron injury in a rat model of Alzheimer＇s disease （AD）. Methods Male Sprague-Dawley rats were pretreated with R. rosea extract at doses of 1.5, 3.0, and 6.0 g/kg for 3 weeks, followed by bilateral intracerebroventricular injection with streptozotocin （1.5 mg/kg） on days 1 and 3. Behavioral alterations were monitored after 2 weeks from the lesion using Morris water maze task. Three weeks after the lesion, the rats were sacrificed for measuring the malondialdehyde （MDA）, glutathione reductase （GR） and reduced glutathione （GSH） levels in hippocampus and histopathology of hippocampal neurons. Results The MDA level was significantly increased while the GR and GSH levels were significantly decreased with striking impairments in spatial learning and memory and severe damage to hippocampal neurons in the model rat induced by intracerebroventricular injection of streptozotocin. These abnormalities were significantly improved by pretreatment with R. rosea extract （3.0 g/kg）. Conclusion R. rosea extract can protect rats against cognitive deficits, neuronal injury and oxidative stress induced by intracerebroventricular injection of streptozotocin, and may be used as a potential agent in treatment of neurodegenerative diseases such as AD.

Neuroprotective effects of statins against amyloid β-induced neurotoxicity

A growing body of evidence suggests that disruption of the homeostasis of lipid metabolism affects the pathogenesis of Alzheimer＇s disease （AD）. In particular, dysregulation of cholesterol homeostasis in the brain has been reported to considerably increase the risk of developing AD. Thus, dysregulation of lipid homeostasis may increase the amyloid β （Aβ） levels by affecting amyloid precursor protein （APP） cleavage, which is the most important risk factor involved in the pathogenesis of AD. Previous research demonstrated that Aβ can trigger neuronal insulin resistance, which plays an important role in response to Aβ-induced neurotoxicity in AD. Epidemiological studies also suggested that statin use is associated with a decreased incidence of AD. Therefore, statins are believed to be a good candidate for conferring neuropro- tective effects against AD. Statins may play a beneficial role in reducing A^-induced neurotoxicity. Their effect involves a putative mechanism beyond its cholesterol-lowering effects in preventing A[3-induced neurotoxicity. However, the underlying molecular mechanisms of the protective effect of statins have not been clearly determined in Aβ-induced neurotoxicity. Given that statins may provide benefits beyond the inhibition of 3-hydroxy-3-methylglutaryl coenzyme A （HMG-CoA） reductase, these drugs may also improve the brain. Thus, statins may have beneficial effects on impaired insulin signaling by activating AMP-activated protein kinase （AMPK） in neuronal cells. They play a potential therapeutic role in targeting Aβ-mediated neurotoxicity.

Kongsheng Zhenzhong pill's effect on the learning and memory ability and its neuroprotective effects in vascular dementia rats

Clinical reports have demonstrated that the Kongsheng Zhenzhong pill （KSZZP）, a classical prescription deriving from Valuable Prescription for Emergencies, has good therapeutic effects on vascular dementia. However, the mechanisms that mediate its effects remain unclear. In this study, the expression of N-methyI-D-aspartate receptor 1 mRNA, the content of nitric oxide, and the concentration of calcium in neurons was determined with in situ hybridization, spectrophotometry and flow cytometry, respectively. In addition, the expressions of N-methyI-D-aspartate receptor 1, nerve growth factor protein, and glial cell line-derived neurotrophic factor protein were detected with immunohistochemistry. We found that KSZZP could significantly decrease the expression of N-methyI-D-aspartate receptor 1 mRNA and protein, the content of nitric oxide, and the concentration of calcium in neurons. KSZZP also increased the expression of nerve growth factor and glial cell line-derived neurotrophic factor protein in the hippocampus CA1 region and in the cerebral cortex. Morris water maze and passive avoidance tests verified that KSZZP ameliorated the cognitive impairments of vascular dementia rats. Moreover, the KSZZP-induced improvements in the cognitive functions of vascular dementia rats were correlated with both inhibition of N-methyl-D-aspartate-induced excitable neurotoxicity and elevation of neurotrophic factor expression.

Exosomal microRNAs from mesenchymal stem/stromal cells: Biology and applications in neuroprotection

Mesenchymal stem/stromal cells(MSCs)are extensively studied as cell-therapy agents for neurological diseases.Recent studies consider exosomes secreted by MSCs as important mediators for MSCs’neuroprotective functions.Exosomes transfer functional molecules including proteins,lipids,metabolites,DNAs,and coding and non-coding RNAs from MSCs to their target cells.Emerging evidence shows that exosomal microRNAs(miRNAs)play a key role in the neuroprotective properties of these exosomes by targeting several genes and regulating various biological processes.Multiple exosomal miRNAs have been identified to have neuroprotective effects by promoting neurogenesis,neurite remodeling and survival,and neuroplasticity.Thus,exosomal miRNAs have significant therapeutic potential for neurological disorders such as stroke,traumatic brain injury,and neuroinflammatory or neurodegenerative diseases and disorders.This review discusses the neuroprotective effects of selected miRNAs(miR-21,miR-17-92,miR-133,miR-138,miR-124,miR-30,miR146a,and miR-29b)and explores their mechanisms of action and applications for the treatment of various neurological disease and disorders.It also provides an overview of state-of-the-art bioengineering approaches for isolating exosomes,optimizing their yield and manipulating the miRNA content of their cargo to improve their therapeutic potential.

The neuroprotective effects of the anti-diabetic drug linagliptin against Aβ-induced neurotoxicity

Impaired insulin signaling in Alzheimer’s disease（AD）brains：The insulin signaling pathway is a fundamental physiological mechanism that presents in nearly all vertebrate cells.However,sometimes cells stop responding properly to insulin stimulation.This condition is known as insulin resistance,which is a hallmark of two very common conditions,metabolic syndrome and type 2 diabetes（T2D）.

Interferon beta(IFN-β) treatment exerts potential neuroprotective effects through neurotrophic factors and novel neurotensin/neurotensin high affinity receptor 1 pathway

Multiple sclerosis（MS）is a chronic autoimmune disease of the central nervous system（CNS）characterized by coexisting processes of inflammation,demyelination,axonal neurodegeneration,and gliosis.It is the most common disabling neurological disease in young adulthood.

Effects of natural-cerebrolysin-containing serum on neurotoxicity and synaptogenesis in amyloid-beta 1-40-induced Alzheimer's disease in vitro models

BACKGROUND： Neuronal loss, synapse mutilation, and increasing malnourished axons are pathologically related to Alzheimer＇s disease. Microtubule-associated protein 2 （MAP2） is of importance for neuronal, axonal, and dendritic generation, extension, and stabilization, as well as for the regulation of synaptic plasticity. OBJECTIVE： To investigate the antagonistic effects of natural-cerebrolysin-containing serum on beta amyloid protein 1-40 （Aβ1-40）-induced neurotoxicity from the standpoints of cell proliferation, synaptogenesis, and cytoskeleton formation （MAP2 expression）. DESIGN, TIME AND SETTING： A paralleled, controlled, neural cell, and molecular biology experiment was performed at the Institute of Integrated Chinese and Western Medicine, Shenzhen Hospital, Southern Medical University between February 2006 and April 2008. MATERIALS： PC12 cells, derived from the rat central nervous system, were purchased from Shanghai Institute of Cell Biology, Chinese Academy of Sciences, China. A β1-40 was provided by Sigma, USA. Natural-cerebrolysin was provided by Shenzhen Institute of Integrated Chinese and Western Medicine, China. The natural-cerebrolysin was predominantly composed of Renshen （Radix Ginseng）, Tianma （Rhizoma Gastrodiae）, and Yixingye （Ginkgo Leaf） in a proportion of 1：2：2. Following conventional water extraction technology, an extract （1：20） was prepared. Each gram of extract equaled 20 grams of crude drug. In a total of 12 adult male New Zealand rabbits, six underwent intragastric administration of natural-cerebrolysin extract for 1 month to prepare natural-cerebrolysin-containing serum, and the remaining six rabbits received intragastric administration of physiological saline to prepare normal blank serum. METHODS： An AIzheimer＇s disease in vitro model was induced in PC12 cells using Aβ1-40. The cells were incubated with varying doses of natural-cerebrolysin-containing serum （2.5%, 5%, and 10%）. Normal blank serum-treated PC12 cells served as a blank control group. MAIN OUTCOME MEASURES： Through the use of inverted phase contrast microscope, cell morphology and neurite growth were observed, neurite length was measured, and the percentage of neurite-positive cells was calculated. Cell proliferation rate was determined by MTT assay, and MAP 2 expression was detected by fluorescent immunocytochemistry. RESULTS： Following Aβ1-40 treatments, some PC12 cells were apoptotic/dying, and only a few short neurites were observed. Following interventions with natural-cerebrolysin-containing serum, the PC12 cells proliferated, there was an increased number of neurites, and neurite length was enhanced. After middle- and high-dose natural-cerebrolysin treatments, the percentage of neurite-positive cells, as well as the average length of neurites, was significantly greater than the normal blank serum-treated PC12 cells （P 〈 0.05 or P 〈 0.01）. Compared with the blank control group, MAP2 expression in the Aβ1-40-treated PC12 cells was significantly inhibited, and the cell proliferation rate was significantly decreased （P 〈 0.01）. Following incubations with natural-cerebrolysin-containing serum, MAP2 expression and cell proliferation rate in the PC12 cells were significantly increased in a dose-dependent manner, compared with treatments with blank control serum （P 〈 0.05 or P 〈 0.01 ）. CONCLUSION： Natural-cerebrolysin exhibited antagonistic effects on neurotoxicity in Aβ1-40 induced Alzheimer＇s disease in vitro models. These effects were likely related to cell proliferation and the upregulation of intracellular MAP2 expression.

Chemical constituents isolated from the aerial parts of Swertia pseudochinensis and their potential neuroprotective effects

Objective:Swertia pseudochinensis,an annual herb of the genus Swertia in the family Gentianaceae.Some constituents and extracts from the Swertia genus have been recently reported to possess neuroprotective effects,suggesting their potential utility in the prevention and treatment of Parkinson disease(PD).The aim of this work is to identify the chemical constituents and evaluate the potential biological activists of Swertia pseudochinensis.Methods:The phytochemicals from the aerial parts of S.pseudochinensis were isolated and purified by silica gel,Sephadex LH-20 gel,semi-preparative high-performance liquid chromatography,and identified by the spectroscopic methods.All compounds were evaluated for their potential neuroprotective effects against 1-methyl-4-phenylpyridinium-induced apoptosis in the SH-SY5Y human neuroblastoma cell line using the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay.Then,we performed an enrichment analysis using the Database for Annotation,Visualization,and Integrated Discovery and investigated the mechanisms by which bellidifolin regulates neurodegenerative disease.Results:Two new anthraquinone,1,5,6-trimethoxy-2-hydroxy-3-methy-anthraquinone(1)and 1,5,6,8-tetramethoxy-2-hydroxy-3-methyanthraquinone(2),together with nine known including 7-O-b-d-glucopyranosyl-1,8-dihydroxy-3-methoxyxanthone(3),gentisin(4),swertianolin(5),bellidifolin(6),gentiacaulein(7),norswertianolin(8),5-O-b-d-glucopyranosyl-1,3,8-trihydroxyapatone(9),1-hydroxy-3,5,8-trimethoxyxanthone(10),and aurantio-obtusin(11),were isolated and compounds 6–8 and 10 exhibited neuroprotective effects at a concentration of 50mmol/L.Among them,bellidifolin showed significant protective activity,and might have potential as a neuroprotective agent for the treatment of PD,possibly by acting on oxidative damage and reactive oxygen species.Conclusions:These findings indicate that further research on the genus Swertia and its bioactive constituents toward neurodegenerative disorders could be extremely rewarding.

Mercury-induced neurotoxicity and neuroprotective effects of berberine

Exposure to mercury can cause immune, sensory, neurological, motor and behavioral dysfunctions similar to traits associated with autism spectrum disorders （ASDs）, and these similarities extend to neuroanatomy, neurotransmitters and biochemistry. It also affects antioxidant system in the cell, resulting in loss of membrane integrity and finally cellular necrosis （Abdel Moneim, 2015）.

A new peptide,VD11,promotes structural and functional recovery after spinal cord injury

The regenerative capacity of the central nervous system is very limited and few effective treatments are currently available for spinal cord injury.It is therefore a priority to develop new drugs that can promote structural and functional recovery after spinal cord injury.Previous studies have shown that peptides can promote substantial repair and regeneration of injured tissue.While amphibians have a pronounced ability to regenerate the spinal cord,few studies have investigated the effect of amphibian spinal cord-derived peptides on spinal cord injury.Here we report for the first time the successful identification and isolation of a new polypeptide,VD11(amino acid sequence:VDELWPPWLPC),from the spinal cord of an endemic Chinese amphibian(Odorrana schmackeri).In vitro experiments showed that VD11 promoted the secretion of nerve growth factor and brain-derived neurotrophic factor in BV2 cells stimulated with lipopolysaccharide,as well as the proliferation and synaptic elongation of PC12 cells subjected to hypoxia.In vivo experiments showed that intravertebral injection of VD11 markedly promoted recovery of motor function in rats with spinal cord injury,alleviated pathological damage,and promoted axonal regeneration.Furthermore,RNA sequencing and western blotting showed that VD11 may affect spinal cord injury through activation of the AMPK and AKT signaling pathways.In summary,we discovered a novel amphibian-derived peptide that promotes structural and functional recovery after spinal cord injury.

Pharmacological Action and Molecular Mechanism of Amentoflavone

Amentoflavone(AMF)is a natural active substance extracted from Chinese herbal medicine Selaginella tamariscina,and has good anti-inflammatory,antitumor,hypoglycemic and neuroprotective pharmacological effects.This paper reviews the pharmacological action and mechanism of AMF,in order to lay a theoretical foundation for in-depth research and drug development of AMF.

Therapeutic potential of Gastrodia elata Blume for the treatment of Alzheimer's disease

Several studies have demonstrated that the Chinese herb Gastrodia elata Blume can protect against amyloid beta-peptide （Ap）-induced cell death. To investigate the possible therapeutic effects of Gastrodia elata Blume on Alzheimer＇s disease, we established a rat model of AIzheimer＇s disease by injecting A325-35 into bilateral hippocampi. These rats were intragastrically administered 500 or 1 000 mg/kg Gastrodia elata Blume per day for 52 consecutive days. Morris water maze tests showed that Gastrodia elata Blume treatment significantly improved the spatial memory of Alzheimer＇s disease rats. Congo red staining revealed that Gastrodia elata Blume significantly reduced the number of amyloid deposits in the hippocampus of these rats. Western blot analysis showed that choline acetyltransferase expression in the medial septum and hippocampus was significantly increased by the treatment of Gastrodia elata Blume, while EIIman method showed significant decrease in the activity of acetylcholinesterase in all three regions （prefrontal cortex, medial septum and hippocampus）. These findings suggest that long-term administration of Gastrodia elata Blume has therapeutic potential for Alzheimer＇s disease.

Brain-derived neurotrophic factor mediates macrophage migration inhibitory factor to protect neurons against oxygen-glucose deprivation

Macrophage migration inhibitory factor(MIF)is a chemokine that plays an essential role in immune system function.Previous studies suggested that MIF protects neurons in ischemic conditions.However,few studies are reported on the role of MIF in neurological recovery after ischemic stroke.The purpose of this study is to identify the molecular mechanism of neuroprotection mediated by MIF.Human neuroblastoma cells were incubated in Dulbecco’s modified Eagle’s medium under oxygen-glucose deprivation(OGD)for 4 hours and then returned to normal aerobic environment for reperfusion(OGD/R).30 ng/mL MIF recombinant(30 ng/mL)or ISO-1(MIF antagonist;50μM)was administered to human neuroblastoma cells.Then cell cultures were assigned to one of four groups:control,OGD/R,OGD/R with MIF,OGD/R with ISO-1.Cell viability was analyzed using WST-1 assay.Expression levels of brain-derived neurotrophic factor(BDNF),microtubule-associated protein 2(MAP2),Caspase-3,Bcl2,and Bax were detected by western blot assay and immunocytochemistry in each group to measure apoptotic activity.WST-1 assay results revealed that compared to the OGD/R group,cell survival rate was significantly higher in the OGD/R with MIF group and lower in the OGD/R with ISO-1 group.Western blot assay and immunocytochemistry results revealed that expression levels of BDNF,Bcl2,and MAP2 were significantly higher,and expression levels of Caspase-3 and Bax were significantly lower in the MIF group than in the OGD/R group.Expression levels of BDNF,Bcl2,and MAP2 were significantly lower,and expression levels of Caspase-3 and Bax were significantly higher in the ISO-1 group than in the OGD/R group.MIF administration promoted neuronal cell survival and induced high expression levels of BDNF,MAP2,and Bcl2(anti-apoptosis)and low expression levels of Caspase-3 and Bax(pro-apoptosis)in an OGD/R model.These results suggest that MIF administration is effective for inducing expression of BDNF and leads to neuroprotection of neuronal cells against hypoxic injury.

Astragaloside Ⅳ protects RGC-5 cells against oxidative stress

Astragaloside Ⅳ is the main active compound of Astragalus membranaceus. Astragaloside Ⅳ has strong anti-oxidative activities and protective effects against progression of peripheral neuropathy. In this study, we determined whether astragaloside Ⅳ protects retinal ganglion cells（RGC） from oxidative stress injury using the rat RGC-5 cell line. Hydrogen peroxide（H_2O_2） was used to induce oxidative stress injury, with the protective effect of astragaloside Ⅳ examined. Cell Counting Kit-8 and 4′,6-diamidino-2-phenylindole staining showed that astragaloside Ⅳ increased cell survival rate and decreased apoptotic cell number. Flow cytometry showed that astragaloside Ⅳ decreased H_2O_2-induced reactive oxygen species levels. While laser confocal microscopy showed that astragaloside Ⅳ inhibited the H_2O_2-induced decrease of mitochondrial membrane potential. Western blot assay showed that astragaloside Ⅳ reduced cytochrome c release induced by H_2O_2, inhibited Bax and caspase-3 expression, and increased Bcl-2 expression. Altogether, these results indicate that astragaloside Ⅳ has potential protective effects against H_2O_2-induced oxidative stress in retinal ganglion cells.

Restorative effect and mechanism of mecobalamin on sciatic nerve crush injury in mice

Mecobalamin, a form of vitamin B12 containing a central metal element （cobalt）, is one of the most important mediators of nervous system function. In the clinic, it is often used to accelerate recovery of peripheral nerves, but its molecular mechanism remains unclear. In the present study, we performed sciatic nerve crush injury in mice, followed by daily intraperitoneal administra-tion of mecobalamin （65 μg/kg or 130 μg/kg） or saline （negative control）. Walking track analysis, histomorphological examination, and quantitative real-time PCR showed that mecobalamin signiifcantly improved functional recovery of the sciatic nerve, thickened the myelin sheath in myelinated nerve ifbers, and increased the cross-sectional area of target muscle cells. Further-more, mecobalamin upregulated mRNA expression of growth associated protein 43 in nerve tissue ipsilateral to the injury, and of neurotrophic factors （nerve growth factor, brain-derived nerve growth factor and ciliary neurotrophic factor） in the L4–6 dorsal root ganglia. Our ifndings indicate that the molecular mechanism underlying the therapeutic effect of mecobalamin after sciatic nerve injury involves the upregulation of multiple neurotrophic factor genes.

Interleukin-4 promotes microglial polarization toward a neuroprotective phenotype after retinal ischemia/reperfusion injury

Glaucoma results from irreversible loss of retinal ganglion cells(RGCs)through an unclear mechanism.Microglial polarization and neuroinflammation play an important role in retinal degeneration.Our study aimed to explore the function of microglial polarization during glaucoma progression and identify a strategy to alleviate retinal neuroinflammation.Retinal ischemia/reperfusion injury was induced in C57BL/6 mice.In a separate cohort of animals,interleukin(IL)-4(50 ng/mL,2μL per injection)or vehicle was intravitreally injected after retinal ischemia/reperfusion injury.RGC loss was assessed by counting cells that were positive for the RGC marker RNA binding protein,mRNA processing factor in retinal flat mounts.The expression of classically activated(M1)and alternatively activated(M2)microglial markers were assessed by quantitative reverse transcription-polymerase chain reaction,immunofluorescence,and western blotting.The results showed that progressive RGC loss was accompanied by a continuous decrease in M2 microglia during the late phase of the 28-day period after retinal ischemia/reperfusion injury.IL-4 was undetectable in the retina at all time points,and intravitreal IL-4 administration markedly improved M2 microglial marker expression and ameliorated RGC loss in the late phase post-retinal ischemia/reperfusion injury.In summary,we observed that IL-4 treatment maintained a high number of M2 microglia after RIR and promoted RGC survival.