Objective Antimony(Sb)has recently been identified as a novel nerve poison,although the cellular and molecular mechanisms underlying its neurotoxicity remain unclear.This study aimed to assess the effects of the nucle...Objective Antimony(Sb)has recently been identified as a novel nerve poison,although the cellular and molecular mechanisms underlying its neurotoxicity remain unclear.This study aimed to assess the effects of the nuclear factor kappa B(NF-κB)signaling pathway on antimony-induced astrocyte activation.Methods Protein expression levels were detected by Western blotting.Immunofluorescence,cytoplasmic and nuclear fractions separation were used to assess the distribution of p65.The expression of protein in brain tissue sections was detected by immunohistochemistry.The levels of mRNAs were detected by Quantitative real-time polymerase chain reaction(qRT-PCR)and reverse transcriptionpolymerase chain reaction(RT-PCR).Results Antimony exposure triggered astrocyte proliferation and increased the expression of two critical protein markers of reactive astrogliosis,inducible nitric oxide synthase(iNOS)and glial fibrillary acidic protein(GFAP),indicating that antimony induced astrocyte activation in vivo and in vitro.Antimony exposure consistently upregulated the expression of inflammatory factors.Moreover,it induced the NF-κB signaling,indicated by increased p65 phosphorylation and translocation to the nucleus.NF-κB inhibition effectively attenuated antimony-induced astrocyte activation.Furthermore,antimony phosphorylated TGF-β-activated kinase 1(TAK1),while TAK1 inhibition alleviated antimonyinduced p65 phosphorylation and subsequent astrocyte activation.Conclusion Antimony activated astrocytes by activating the NF-κB signaling pathway.展开更多
OBJECTIVE Astrocytes activa⁃tion and glial scar formation are the important causes that hinder the recovery of motor function after cerebral ischemia.However,its precise mechanism has not been clarified.Peroxisome pro...OBJECTIVE Astrocytes activa⁃tion and glial scar formation are the important causes that hinder the recovery of motor function after cerebral ischemia.However,its precise mechanism has not been clarified.Peroxisome proliferator-activated receptorα(PPARα)is a ligand-activated nuclear transcriptional factor.This study aims to further clarify the role of PPARαin astrocyte activation after cerebral isch⁃emia and explore the underlying mechanism.METHODS Astrocyte activation in vivo model was induced by transient middle cerebral artery occlusion(tMCAO)in mice and in vitro model was induced by oxygen-glucose deprivation/reox⁃ygenation(OGD/R)in primary culture of mouse astrocyte.The effects of PPARαon astrocyte ac⁃tivation and autophagy flux were observed in the condition of PPARαdysfunction(PPARαnull mice)or PPARαactivation by oleoylethanol⁃amide(OEA).RESULTS PPARαmainly ex⁃pressed in activated astrocytes during the chron⁃ic phase of brain ischemia and PPARαdysfunc⁃tion promoted astrocytes activation after brain ischemia in vivo and in vitro.After cerebral isch⁃emia,the expressions of LC3-Ⅱ/Ⅰand P62 both increased in the brain tissue near the infarct core.Autophagic vesicles accumulation was ob⁃served by electron microscopy in astrocytes,and mRFP-GFP-LC3 adenovirus infection assay indi⁃cated the block of autophagy flux.PPARαdys⁃function aggravated autophagy flux block,while PPARαactivation preserved the lysosome func⁃tion and restored autophagy flux in astrocytes after OGD/R.Autophagy flux blocker bafilomycin A1 and chloroquine antagonized the effect of OEA on inhibiting astrocyte activation.CONCLU⁃SION PPARαactivation inhibites the over-activa⁃tion of astrocytes by restoring the autophagy flux after cerebral ischemia.展开更多
The accumulation of pathological α-synuclein(α-syn)in the central nervous system and the progressive loss of dopaminergic neurons in the substantia nigra pars compacta are the neuropathological features of Parkinson...The accumulation of pathological α-synuclein(α-syn)in the central nervous system and the progressive loss of dopaminergic neurons in the substantia nigra pars compacta are the neuropathological features of Parkinson's disease(PD).Recently,the findings of prion-like transmission of α-syn pathology have expanded our understanding of the region-specific distribution ofα-syn in PD patients.Accumulating evidence suggests that α-syn aggregates are released from neurons and endocytosed by glial cells,which contributes to the clearance of α-syn.However,the activation of glial cells by α-syn species produces pro-inflammatory factors that decrease the uptake of α-syn aggregates by glial cells and promote the transmission of α-syn between neurons,which promotes the spread of α-syn pathology.In this article,we provide an overview of current knowledge on the role of glia and α-syn pathology in PD pathogenesis,highlighting the relationships between glial responses and the spread ofα-syn pathology.展开更多
Circadian rhythm protects neurons：Although the master clock entrains the whole body rhythm,peripheral tissues also express core clock transcription factors Clock and Bmal1,which regulate expression of clock genes inc...Circadian rhythm protects neurons：Although the master clock entrains the whole body rhythm,peripheral tissues also express core clock transcription factors Clock and Bmal1,which regulate expression of clock genes including Period（Per）and Cryptochrome（Cry）proteins.Complexes of Per and Cry proteins repress Bmal1-and Clock-mediated transcription forming a negative feedback loop,which regulates nearly a 24 hours self-sustained rhythm including energy metabolism.展开更多
AIM:To analyze visual dysfunction in rats under simulated weightlessness(SW)by examining trans-laminar cribrosa pressure difference(TLCPD)and neuroimmune responses.METHODS:The 72 male Sprague-Dawley rats were randomly...AIM:To analyze visual dysfunction in rats under simulated weightlessness(SW)by examining trans-laminar cribrosa pressure difference(TLCPD)and neuroimmune responses.METHODS:The 72 male Sprague-Dawley rats were randomly assigned into two groups(ground control and hindlimb unloading-simulated microgravity)using stratified randomization,with each group further subdivided into three exposure durations:SW 2-week(SW-2W),4-week(SW-4W),and 8-week(SW-8W),n=12 per subgroup.At the designated time points for each group,intraocular pressure(IOP)and intracranial pressure(ICP)were measured,and the trans-laminar cribrosa pressure difference(TLCPD)was calculated.Additionally,optomotor response(OMR),electroretinography(ERG),and optical coherence tomography(OCT)were performed.The number of retinal ganglion cells(RGCs)was quantified via immunofluorescence,the activation of astrocytes and microglial cells was determined,and Sholl analysis was conducted to assess the function and morphology of microglial cells.Data were analyzed with SPSS and GraphPad Prism(P<0.05).RESULTS:Under prolonged simulated microgravity,rats exhibited a progressive increase in both IOP and ICP,with the most pronounced rise observed at 8wk.Concurrently,the TLCPD shifted from a negative value in controls to a positive value.These pressure alterations were associated with retinal dysfunction,as evidenced by significant reductions in ERG b-wave and photopic negative response(PhNR)amplitudes.OCT and histological analyses revealed subtle photoreceptor layer damage:while the inner nuclear layer(INL)thickness remained relatively unchanged,the outer nuclear layer(ONL)thinned significantly,and the nerve fiber layer-ganglion cell layer complex thickness(NFL-GCL)complex initially thickened before later thinning.Immunofluorescence further demonstrated marked neuroimmune activation,with astrocytes transitioning from having large cell bodies with small,elongated,sparse processes to a phenotype characterized by compact,enlarged nuclei and aggregated processes,alongside notable RGC loss.CONCLUSION:Based on the results from the simulated microgravity rat model,microgravity-induced changes in dual-chamber pressure,and neuroimmune responses in the retina may play a key role in visual dysfunction.Specifically,the activation of retinal neuroimmune cells(astrocytes and microglial cells)induced by mechanical stress appears to be central to retinal and optic nerve damage.展开更多
Glial scarring following severe tissue damage and inflammation after spinal cord injury （SCI） is due to an extreme, uncontrolled form of reactive astrogliosis that typically occurs around the injury site. The scarri...Glial scarring following severe tissue damage and inflammation after spinal cord injury （SCI） is due to an extreme, uncontrolled form of reactive astrogliosis that typically occurs around the injury site. The scarring process includes the misalignment of activated astrocytes and the deposition of inhibitory chondroitin sulfate proteoglycans. Here, we first discuss recent developments in the molecular and cellular features of glial scar formation, with special focus on the potential cellular origin of scar-forming cells and the molecular mechanisms underlying glial scar formation after SCI. Second, we discuss the role of glial scar formation in the regulation of axonal regeneration and the cascades of neuro-inflammation. Last, we summarize the physical and pharmacological approaches targeting the modulation of glial scarring to better understand the role of glial scar formation in the repair of SCI.展开更多
Astrocytes play an important role in the nervous system’s response to external stimulation.Environmental pollutants could activate astrocytes into A1(toxic)or A2(protective)types and induce different effects.Meanwhil...Astrocytes play an important role in the nervous system’s response to external stimulation.Environmental pollutants could activate astrocytes into A1(toxic)or A2(protective)types and induce different effects.Meanwhile,the aryl hydrocarbon receptor(AhR)is an environmental molecule sensor in the body and has various ligands.But the difference between exogenous and endogenous AhR ligands on the astrocytic activation is unclear;in this study,we employed rat primary cultured cortical astrocytes to reveal the effects and mechanisms of AhR ligands on astrocytic activation.We found that,after treatment with exogenous AhR ligand(2,3,7,8-tetrachlorodibenzo-p-dioxin,TCDD)ranging from 0.01 to 0.1 nmol/L,astrocytes mainly exhibited A2 type activation.The specific manifestation includes the increase in the expression of A2 marker genes,the enhancement of cellular autonomous movement,the expression and secretion of chemokines,such as Cxcl10,Cxcl2,and Ccl7.And TCDD-induced A2 type astrocytes show a positive impact on neuronal synaptic formation.Although both TCDD and endogenous AhR ligand(6-formylindolo[3,2-b]carbazole,FICZ)could activate AhR pathway in astrocytes,FICZ(50 nmol/L)neither induces activation of A2 type astrocytes nor upregulation of chemokines.Therefore,our findings suggest that AhR is crucial for astrocytes to recognize environmental pollutants and protect the nervous system.展开更多
A critical gap currently exists in systematic understanding and experimental validation of the role of astrocytes in neurovascular coupling and their functional links with other brain cells.Despite a broad selection o...A critical gap currently exists in systematic understanding and experimental validation of the role of astrocytes in neurovascular coupling and their functional links with other brain cells.Despite a broad selection of functional neuroimaging tools for multi-scale brain interrogations,no methodology currently exists that can discern responses from neural and glial cells while simultaneously mapping the associated hemodynamic activity on a large scale.We present a hybrid multiplexed fluorescence and magnetic resonance imaging(HyFMRI)platform for measuring neuronal and astrocytic activity registered to concurrently recorded brain-wide hemodynamic responses.It features a fiberscope-based imaging system for multichannel fluorescence and optical intrinsic signal recordings and a custom surface radiofrequency coil,which are incorporated into the bore of a preclinical magnetic resonance imaging(MRI)scanner.We used HyFMRI to study peripheral-stimulus-evoked brain responses in mice differentially labeled with RCaMP and GCaMP genetically-encoded calcium indicators.Stimulation-evoked neuronal responses displayed the fastest kinetics and highest activation amplitude followed by astrocytic signals and the hemodynamic responses simultaneously recorded with functional MRI.In addition,the activation traces from neurons and astrocytes exhibited high linear correlation,thus providing direct evidence of astrocytic mediation in neurovascular coupling.This newly developed capacity to capture cell-type-specific calcium signaling alongside whole-brain hemodynamics enables the simultaneous investigation of neuro-glial-vascular interactions in health and disease.HyFMRI thus expands the current neuroimaging toolbox for a wide range of studies into synaptic plasticity,neural circuitry,brain function and disorders.展开更多
Background Intense exercise can cause injury and apoptosis, but few studies have reported its effect on the central nervous system （CNS）. The initial reason for hippocampus injury is the excitotoxicity of glutamate ...Background Intense exercise can cause injury and apoptosis, but few studies have reported its effect on the central nervous system （CNS）. The initial reason for hippocampus injury is the excitotoxicity of glutamate and calcium overload. Intracellular free Ca2＋ （[Ca2＋]i） overload may trigger the apoptosis pathway and neuron damage. The aim of this study was to investigate whether intense exercise could cause hippocampus apoptosis and neuron damage and then to determine which pathway was activated by this apoptosis. Methods We used one bout of swimming exhaustion rats as models. Intracellular [Ca2~]i was measured to estimate the calcium overload by Fura-2/AM immediately after exhaustion; glial fibrillary acidic protein （GFAP） and synaptophysin （SYP） immunofluorescence were performed for estimating astrocyte activation and synapse plasticity 24 hours after exhaustion. Apoptosis cells were displayed using dUTP nick end labelling （TUNEL） stain; endoplasmic reticulum （ER） stress-induced apoptosis pathway and mitochondrial apoptosis pathway were synchronously detected by Western blotting. Results An increasing level of intracellular [Ca2＋]i （P 〈0.01） was found in the hippocampus immediately after exhaustion. GFAP and SYP immunofluorescence showed that the astrocytes are activated, and the synapse plasticity collapsed significantly 24 hours after exhaustion. TUNEL stain showed that the number of apoptosis cells were notably raised （P 〈0.01）; Western blotting of the apoptosis pathway showed increasing levels of caspase-3 cleavage （P 〈0.01）, Bax （P 〈0.01）, caspase-12 cleavage （P 〈0.01）, C/EBP-homologous protein （CHOP） （P 〈0.01）, and phospho-Junamino- terminal kinases （p-JNK; P 〈0.01） and decreasing level of Bcl-2 （P 〈0.01）. Our results proved that exhaustion can induce hippocampus injury and apoptosis by [Ca2＋]i overload, with collapsed synaptic plasticity as the injury pattern and ER stress-induced apoptosis as the activated pathway. Conclusion Intense exercise can cause excessive apoptosis and synapse plasticity damage in the hippocampus with [Ca2＋]i overload as the initial reason, and thus provides leads for therapeutic interventions in the brain health of athletes.展开更多
基金supported by the National Natural Science Foundation of China[21477058,81703255]Scientific Research Project of Nantong of Jiangsu[JC2019027,JC2019137]+2 种基金the Qing Lan Project for Excellent Young Key Teachers of Colleges and Universities of Jiangsu Province(2020)the Postgraduate Research&Practice Innovation Program of Jiangsu Province[KYCX20_2854]Large Instruments Open Foundation of Nantong University[KFJN2054]。
文摘Objective Antimony(Sb)has recently been identified as a novel nerve poison,although the cellular and molecular mechanisms underlying its neurotoxicity remain unclear.This study aimed to assess the effects of the nuclear factor kappa B(NF-κB)signaling pathway on antimony-induced astrocyte activation.Methods Protein expression levels were detected by Western blotting.Immunofluorescence,cytoplasmic and nuclear fractions separation were used to assess the distribution of p65.The expression of protein in brain tissue sections was detected by immunohistochemistry.The levels of mRNAs were detected by Quantitative real-time polymerase chain reaction(qRT-PCR)and reverse transcriptionpolymerase chain reaction(RT-PCR).Results Antimony exposure triggered astrocyte proliferation and increased the expression of two critical protein markers of reactive astrogliosis,inducible nitric oxide synthase(iNOS)and glial fibrillary acidic protein(GFAP),indicating that antimony induced astrocyte activation in vivo and in vitro.Antimony exposure consistently upregulated the expression of inflammatory factors.Moreover,it induced the NF-κB signaling,indicated by increased p65 phosphorylation and translocation to the nucleus.NF-κB inhibition effectively attenuated antimony-induced astrocyte activation.Furthermore,antimony phosphorylated TGF-β-activated kinase 1(TAK1),while TAK1 inhibition alleviated antimonyinduced p65 phosphorylation and subsequent astrocyte activation.Conclusion Antimony activated astrocytes by activating the NF-κB signaling pathway.
基金National Natural Science Foundation of China(81603093)and the Open Research Fund of State Key Laboratory of Cellu⁃lar Stress Biology,Xiamen University(SKLC⁃SB2019KF016)。
文摘OBJECTIVE Astrocytes activa⁃tion and glial scar formation are the important causes that hinder the recovery of motor function after cerebral ischemia.However,its precise mechanism has not been clarified.Peroxisome proliferator-activated receptorα(PPARα)is a ligand-activated nuclear transcriptional factor.This study aims to further clarify the role of PPARαin astrocyte activation after cerebral isch⁃emia and explore the underlying mechanism.METHODS Astrocyte activation in vivo model was induced by transient middle cerebral artery occlusion(tMCAO)in mice and in vitro model was induced by oxygen-glucose deprivation/reox⁃ygenation(OGD/R)in primary culture of mouse astrocyte.The effects of PPARαon astrocyte ac⁃tivation and autophagy flux were observed in the condition of PPARαdysfunction(PPARαnull mice)or PPARαactivation by oleoylethanol⁃amide(OEA).RESULTS PPARαmainly ex⁃pressed in activated astrocytes during the chron⁃ic phase of brain ischemia and PPARαdysfunc⁃tion promoted astrocytes activation after brain ischemia in vivo and in vitro.After cerebral isch⁃emia,the expressions of LC3-Ⅱ/Ⅰand P62 both increased in the brain tissue near the infarct core.Autophagic vesicles accumulation was ob⁃served by electron microscopy in astrocytes,and mRFP-GFP-LC3 adenovirus infection assay indi⁃cated the block of autophagy flux.PPARαdys⁃function aggravated autophagy flux block,while PPARαactivation preserved the lysosome func⁃tion and restored autophagy flux in astrocytes after OGD/R.Autophagy flux blocker bafilomycin A1 and chloroquine antagonized the effect of OEA on inhibiting astrocyte activation.CONCLU⁃SION PPARαactivation inhibites the over-activa⁃tion of astrocytes by restoring the autophagy flux after cerebral ischemia.
基金supported by the National Natural Science Foundation of China(32271039,32070970 and 31871023)the Joint Program RFBR-BRICS(17-54-80006)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘The accumulation of pathological α-synuclein(α-syn)in the central nervous system and the progressive loss of dopaminergic neurons in the substantia nigra pars compacta are the neuropathological features of Parkinson's disease(PD).Recently,the findings of prion-like transmission of α-syn pathology have expanded our understanding of the region-specific distribution ofα-syn in PD patients.Accumulating evidence suggests that α-syn aggregates are released from neurons and endocytosed by glial cells,which contributes to the clearance of α-syn.However,the activation of glial cells by α-syn species produces pro-inflammatory factors that decrease the uptake of α-syn aggregates by glial cells and promote the transmission of α-syn between neurons,which promotes the spread of α-syn pathology.In this article,we provide an overview of current knowledge on the role of glia and α-syn pathology in PD pathogenesis,highlighting the relationships between glial responses and the spread ofα-syn pathology.
基金support of JSPS KAKENHI Grant Number 21500386 (TI)British Heart Foundation (GEM, FS/15/31298 FS/16/67/32548)
文摘Circadian rhythm protects neurons：Although the master clock entrains the whole body rhythm,peripheral tissues also express core clock transcription factors Clock and Bmal1,which regulate expression of clock genes including Period（Per）and Cryptochrome（Cry）proteins.Complexes of Per and Cry proteins repress Bmal1-and Clock-mediated transcription forming a negative feedback loop,which regulates nearly a 24 hours self-sustained rhythm including energy metabolism.
文摘AIM:To analyze visual dysfunction in rats under simulated weightlessness(SW)by examining trans-laminar cribrosa pressure difference(TLCPD)and neuroimmune responses.METHODS:The 72 male Sprague-Dawley rats were randomly assigned into two groups(ground control and hindlimb unloading-simulated microgravity)using stratified randomization,with each group further subdivided into three exposure durations:SW 2-week(SW-2W),4-week(SW-4W),and 8-week(SW-8W),n=12 per subgroup.At the designated time points for each group,intraocular pressure(IOP)and intracranial pressure(ICP)were measured,and the trans-laminar cribrosa pressure difference(TLCPD)was calculated.Additionally,optomotor response(OMR),electroretinography(ERG),and optical coherence tomography(OCT)were performed.The number of retinal ganglion cells(RGCs)was quantified via immunofluorescence,the activation of astrocytes and microglial cells was determined,and Sholl analysis was conducted to assess the function and morphology of microglial cells.Data were analyzed with SPSS and GraphPad Prism(P<0.05).RESULTS:Under prolonged simulated microgravity,rats exhibited a progressive increase in both IOP and ICP,with the most pronounced rise observed at 8wk.Concurrently,the TLCPD shifted from a negative value in controls to a positive value.These pressure alterations were associated with retinal dysfunction,as evidenced by significant reductions in ERG b-wave and photopic negative response(PhNR)amplitudes.OCT and histological analyses revealed subtle photoreceptor layer damage:while the inner nuclear layer(INL)thickness remained relatively unchanged,the outer nuclear layer(ONL)thinned significantly,and the nerve fiber layer-ganglion cell layer complex thickness(NFL-GCL)complex initially thickened before later thinning.Immunofluorescence further demonstrated marked neuroimmune activation,with astrocytes transitioning from having large cell bodies with small,elongated,sparse processes to a phenotype characterized by compact,enlarged nuclei and aggregated processes,alongside notable RGC loss.CONCLUSION:Based on the results from the simulated microgravity rat model,microgravity-induced changes in dual-chamber pressure,and neuroimmune responses in the retina may play a key role in visual dysfunction.Specifically,the activation of retinal neuroimmune cells(astrocytes and microglial cells)induced by mechanical stress appears to be central to retinal and optic nerve damage.
基金supported by grants from the National Basic Research Development Program of China (2011CB504401)the National Natural Science Foundation of China (31130024,31070922 and 81261130313)
文摘Glial scarring following severe tissue damage and inflammation after spinal cord injury （SCI） is due to an extreme, uncontrolled form of reactive astrogliosis that typically occurs around the injury site. The scarring process includes the misalignment of activated astrocytes and the deposition of inhibitory chondroitin sulfate proteoglycans. Here, we first discuss recent developments in the molecular and cellular features of glial scar formation, with special focus on the potential cellular origin of scar-forming cells and the molecular mechanisms underlying glial scar formation after SCI. Second, we discuss the role of glial scar formation in the regulation of axonal regeneration and the cascades of neuro-inflammation. Last, we summarize the physical and pharmacological approaches targeting the modulation of glial scarring to better understand the role of glial scar formation in the repair of SCI.
基金supported by the National Natural Science Foundation of China(No.22206202 and 22206201)the Key Technologies Research and Development Program(No.2018YFA0901100).
文摘Astrocytes play an important role in the nervous system’s response to external stimulation.Environmental pollutants could activate astrocytes into A1(toxic)or A2(protective)types and induce different effects.Meanwhile,the aryl hydrocarbon receptor(AhR)is an environmental molecule sensor in the body and has various ligands.But the difference between exogenous and endogenous AhR ligands on the astrocytic activation is unclear;in this study,we employed rat primary cultured cortical astrocytes to reveal the effects and mechanisms of AhR ligands on astrocytic activation.We found that,after treatment with exogenous AhR ligand(2,3,7,8-tetrachlorodibenzo-p-dioxin,TCDD)ranging from 0.01 to 0.1 nmol/L,astrocytes mainly exhibited A2 type activation.The specific manifestation includes the increase in the expression of A2 marker genes,the enhancement of cellular autonomous movement,the expression and secretion of chemokines,such as Cxcl10,Cxcl2,and Ccl7.And TCDD-induced A2 type astrocytes show a positive impact on neuronal synaptic formation.Although both TCDD and endogenous AhR ligand(6-formylindolo[3,2-b]carbazole,FICZ)could activate AhR pathway in astrocytes,FICZ(50 nmol/L)neither induces activation of A2 type astrocytes nor upregulation of chemokines.Therefore,our findings suggest that AhR is crucial for astrocytes to recognize environmental pollutants and protect the nervous system.
基金support from the Swiss National Science Foundation(SNSF)grant 310030_192757the Fundamental Research Funds for the Central Universities 13702150142the Shanghai Science and Technology Program Project 24ZR1468000.
文摘A critical gap currently exists in systematic understanding and experimental validation of the role of astrocytes in neurovascular coupling and their functional links with other brain cells.Despite a broad selection of functional neuroimaging tools for multi-scale brain interrogations,no methodology currently exists that can discern responses from neural and glial cells while simultaneously mapping the associated hemodynamic activity on a large scale.We present a hybrid multiplexed fluorescence and magnetic resonance imaging(HyFMRI)platform for measuring neuronal and astrocytic activity registered to concurrently recorded brain-wide hemodynamic responses.It features a fiberscope-based imaging system for multichannel fluorescence and optical intrinsic signal recordings and a custom surface radiofrequency coil,which are incorporated into the bore of a preclinical magnetic resonance imaging(MRI)scanner.We used HyFMRI to study peripheral-stimulus-evoked brain responses in mice differentially labeled with RCaMP and GCaMP genetically-encoded calcium indicators.Stimulation-evoked neuronal responses displayed the fastest kinetics and highest activation amplitude followed by astrocytic signals and the hemodynamic responses simultaneously recorded with functional MRI.In addition,the activation traces from neurons and astrocytes exhibited high linear correlation,thus providing direct evidence of astrocytic mediation in neurovascular coupling.This newly developed capacity to capture cell-type-specific calcium signaling alongside whole-brain hemodynamics enables the simultaneous investigation of neuro-glial-vascular interactions in health and disease.HyFMRI thus expands the current neuroimaging toolbox for a wide range of studies into synaptic plasticity,neural circuitry,brain function and disorders.
基金This study was supported by grants from the National Natural Science Foundation of China （No. 30270636 and No. 30671015）.
文摘Background Intense exercise can cause injury and apoptosis, but few studies have reported its effect on the central nervous system （CNS）. The initial reason for hippocampus injury is the excitotoxicity of glutamate and calcium overload. Intracellular free Ca2＋ （[Ca2＋]i） overload may trigger the apoptosis pathway and neuron damage. The aim of this study was to investigate whether intense exercise could cause hippocampus apoptosis and neuron damage and then to determine which pathway was activated by this apoptosis. Methods We used one bout of swimming exhaustion rats as models. Intracellular [Ca2~]i was measured to estimate the calcium overload by Fura-2/AM immediately after exhaustion; glial fibrillary acidic protein （GFAP） and synaptophysin （SYP） immunofluorescence were performed for estimating astrocyte activation and synapse plasticity 24 hours after exhaustion. Apoptosis cells were displayed using dUTP nick end labelling （TUNEL） stain; endoplasmic reticulum （ER） stress-induced apoptosis pathway and mitochondrial apoptosis pathway were synchronously detected by Western blotting. Results An increasing level of intracellular [Ca2＋]i （P 〈0.01） was found in the hippocampus immediately after exhaustion. GFAP and SYP immunofluorescence showed that the astrocytes are activated, and the synapse plasticity collapsed significantly 24 hours after exhaustion. TUNEL stain showed that the number of apoptosis cells were notably raised （P 〈0.01）; Western blotting of the apoptosis pathway showed increasing levels of caspase-3 cleavage （P 〈0.01）, Bax （P 〈0.01）, caspase-12 cleavage （P 〈0.01）, C/EBP-homologous protein （CHOP） （P 〈0.01）, and phospho-Junamino- terminal kinases （p-JNK; P 〈0.01） and decreasing level of Bcl-2 （P 〈0.01）. Our results proved that exhaustion can induce hippocampus injury and apoptosis by [Ca2＋]i overload, with collapsed synaptic plasticity as the injury pattern and ER stress-induced apoptosis as the activated pathway. Conclusion Intense exercise can cause excessive apoptosis and synapse plasticity damage in the hippocampus with [Ca2＋]i overload as the initial reason, and thus provides leads for therapeutic interventions in the brain health of athletes.
