Ginsenoside Rb1 has been reported to exert anti-aging and anti-neurodegenerative effects. In the present study, we investigate whether ginsenoside Rb1 is involved in neurite outgrowth and neuroprotection against damag...Ginsenoside Rb1 has been reported to exert anti-aging and anti-neurodegenerative effects. In the present study, we investigate whether ginsenoside Rb1 is involved in neurite outgrowth and neuroprotection against damage induced by amyloid beta(25–35) in cultured hippocampal neurons, and explore the underlying mechanisms. Ginsenoside Rb1 significantly increased neurite outgrowth in hippocampal neurons, and increased the expression of phosphorylated-Akt and phosphorylated extracellular signal-regulated kinase 1/2. These effects were abrogated by API-2 and PD98059, inhibitors of the signaling proteins Akt and MEK. Additionally, cultured hippocampal neurons were exposed to amyloid beta(25–35) for 30 minutes; ginsenoside Rb1 prevented apoptosis induced by amyloid beta(25–35), and this effect was blocked by API-2 and PD98059. Furthermore, ginsenoside Rb1 significantly reversed the reduction in phosphorylated-Akt and phosphorylated extracellular signal-regulated kinase 1/2 levels induced by amyloid beta(25–35), and API-2 neutralized the effect of ginsenoside Rb1. The present results indicate that ginsenoside Rb1 enhances neurite outgrowth and protects against neurotoxicity induced by amyloid beta(25–35) via a mechanism involving Akt and extracellular signal-regulated kinase 1/2 signaling.展开更多
Ginsenoside Rg1(Rg1) has anti-aging and anti-neurodegenerative effects. However, the mechanisms underlying these actions remain unclear. The aim of the present study was to determine whether Rg1 affects hippocampal ...Ginsenoside Rg1(Rg1) has anti-aging and anti-neurodegenerative effects. However, the mechanisms underlying these actions remain unclear. The aim of the present study was to determine whether Rg1 affects hippocampal survival and neurite outgrowth in vitro after exposure to amyloid-beta peptide fragment 25–35(Aβ_(25–35)), and to explore whether the extracellular signal-regulated kinase(ERK) and Akt signaling pathways are involved in these biological processes. We cultured hippocampal neurons from newborn rats for 24 hours, then added Rg1 to the medium for another 24 hours, with or without pharmacological inhibitors of the mitogen-activated protein kinase(MAPK) family or Akt signaling pathways for a further 24 hours. We then immunostained the neurons for growth associated protein-43, and measured neurite length. In a separate experiment, we exposed cultured hippocampal neurons to Aβ_(25–35) for 30 minutes, before adding Rg1 for 48 hours, with or without Akt or MAPK inhibitors, and assessed neuronal survival using Hoechst 33258 staining, and phosphorylation of ERK1/2 and Akt by western blot analysis. Rg1 induced neurite outgrowth, and this effect was blocked by API-2(Akt inhibitor) and PD98059(MAPK/ERK kinase inhibitor), but not by SP600125 or SB203580(inhibitors of c-Jun N-terminal kinase and p38 MAPK, respectively). Consistent with this effect, Rg1 upregulated the phosphorylation of Akt and ERK1/2; these effects were reversed by API-2 and PD98059, respectively. In addition, Rg1 significantly reversed Aβ_(25–35)-induced apoptosis; this effect was blocked by API-2 and PD98059, but not by SP600125 or SB203580. Finally, Rg1 significantly reversed the Aβ_(25–35)-induced decrease in Akt and ERK1/2 phosphorylation, but API-2 prevented this reversal. Our results indicate that Rg1 enhances neurite outgrowth and protects against Aβ_(25–35)-induced damage, and that its mechanism may involve the activation of Akt and ERK1/2 signaling.展开更多
Breakdown of blood-brain barrier,formed mainly by brain microvascular endothelial cells(BMECs),represents the major cause of mortality during early phases of ischemic strokes.Hence,discovery of novel agents that can e...Breakdown of blood-brain barrier,formed mainly by brain microvascular endothelial cells(BMECs),represents the major cause of mortality during early phases of ischemic strokes.Hence,discovery of novel agents that can effectively replace dead or dying endothelial cells to restore blood-brain barrier integrity is of paramount importance in stroke medicine.Although endothelial progenitor cells(EPCs)represent one such agents,their rarity in peripheral blood severely limits their adequate isolation and therapeutic use for acute ischemic stroke which necessitate their ex vivo expansion and generate early EPCs and outgrowth endothelial cells(OECs)as a result.Functional analyses of these cells,in the present study,demonstrated that only OECs endocytosed DiI-labelled acetylated low-density lipoprotein and formed tubules on matrigel,prominent endothelial cell and angiogenesis markers,respectively.Further analyses by flow cytometry demonstrated that OECs expressed specific markers for sternness(CD34),immaturity(CD133)and endothelial cells(CD31)but not for hematopoietic cells(CD45).Like BMECs,OECs established an equally tight in vitro model of human BBB with astrocytes and pericytes,suggesting their capacity to form tight junctions.Ischemic injury mimicked by concurrent deprivation of oxygen and glucose(4 hours)or deprivation of oxygen and glucose followed by reperfusion(20 hours)affected both barrier integrity and function in a similar fashion as evidenced by decreases in transendothelial electrical resistance and increases in paracellular flux,respectively.Wound scratch assays comparing the vasculoreparative capacity of cells revealed that,compared to BMECs,OECs possessed a greater proliferative and directional migratory capacity.In a triple culture model of BBB established with astrocytes,pericytes and BMEC,exogenous addition of OECs effectively repaired the damage induced on endothelial layer in serum-free conditions.Taken together,these data demonstrate that OECs may effectively home to the site of vascular injury and repair the damage to maintain(neuro)vascular homeostasis during or after a cerebral ischemic injury.展开更多
Proteoglycans in the central nervous system play integral roles as "traffic signals" for the direction of neurite outgrowth. This attribute of proteoglycans is a major factor in regeneration of the injured central n...Proteoglycans in the central nervous system play integral roles as "traffic signals" for the direction of neurite outgrowth. This attribute of proteoglycans is a major factor in regeneration of the injured central nervous system. In this review, the structures of proteoglycans and the evidence suggesting their involvement in the response following spinal cord injury are presented. The review further describes the methods routinely used to determine the effect proteoglycans have on neurite outgrowth. The effects of proteoglycans on neurite outgrowth are not completely understood as there is disagreement on what component of the molecule is interacting with growing neurites and this ambiguity is chronicled in an historical context. Finally, the most recent findings suggesting possible receptors, interactions, and sulfation patterns that may be important in eliciting the effect of proteoglycans on neurite outgrowth are discussed. A greater understanding of the proteoglycan-neurite interaction is necessary for successfully promoting regeneration in the iniured central nervous system.展开更多
15 compounds,including two new ones crepidatuols A(1)and B(2)were isolated from the stems of Dendrobium crepidatum.The planar structures of these compounds were elucidated by spectroscopic methods(NMR,MS,UV,and IR)and...15 compounds,including two new ones crepidatuols A(1)and B(2)were isolated from the stems of Dendrobium crepidatum.The planar structures of these compounds were elucidated by spectroscopic methods(NMR,MS,UV,and IR)and comparison with those from literatures.10 compounds were send for enhancing activities on nerve growth factor(NGF)medicated neurite outgrowth in PC12 cells and the results indicated that crepidatuol A(1),confusarin and 3-(2-acetoxy-5-methoxy)-phenylpropanol showed enhancing activities at the concentration of 10.0μM.展开更多
Spontaneous axonal regeneration of neurons does not occur after spinal cord injury because of inhibition by myelin and other inhibitory factors. Studies have demonstrated that blocking the Rho/Rho-kinase (ROCK) path...Spontaneous axonal regeneration of neurons does not occur after spinal cord injury because of inhibition by myelin and other inhibitory factors. Studies have demonstrated that blocking the Rho/Rho-kinase (ROCK) pathway can promote neurite outgrowth in spinal cord injury models. In the present study, we investigated neurite outgrowth and neuronal differentiation in neural stem cells from the mouse subventricular zone after inhibition of ROCK in vitro. Inhibition of ROCK with Y-27632 increased neurite length, enhanced neuronal differentiation, and upregulated the expression of two major signaling pathway effectors, phospho-Akt and phospho-mitogen-activated protein kinase, and the Hippo pathway effector YAP. These results suggest that inhibition of ROCK mediates neurite outgrowth in neural stem cells by activating the Hippo signaling pathway.展开更多
Previous studies have shown that transplanted enteric glia enhance axonal regeneration, reduce tissue damage, and promote functional recovery following spinal cord injury. However, the mechanisms by which enteric glia...Previous studies have shown that transplanted enteric glia enhance axonal regeneration, reduce tissue damage, and promote functional recovery following spinal cord injury. However, the mechanisms by which enteric glia mediate these beneficial effects are unknown. Neurotrophic factors can promote neuronal differentiation, survival and neurite extension. We hypothesized that enteric glia may exert their protective effects against spinal cord injury partially through the secretion of neurotrophic factors. In the present study, we demonstrated that primary enteric glia cells release nerve growth factor, brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor over time with their concentrations reaching approximately 250, 100 and 50 pg/mL of culture medium respectively after 48 hours. The biological relevance of this secretion was assessed by incubating dissociated dorsal root ganglion neuronal cultures in enteric glia-conditioned medium with and/or without neutralizing antibodies to each of these proteins and evaluating the differences in neurite growth. We discovered that conditioned medium enhances neurite outgrowth in dorsal root ganglion neurons. Even though there was no detectable amount of neurotrophin-3 secretion using ELISA analysis, the neurite outgrowth effect can be attenuated by the antibody-mediated neutralization of each of the aforementioned neurotrophic factors. Therefore, enteric glia secrete nerve growth factor, brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor and neurotrophin-3 into their surrounding environment in concentrations that can cause a biological effect.展开更多
Cerebral cortical neurons from neonatal rats were cultured in the presence of methyl 3,4-dihydroxybenzoate (MDHB; 2, 4, and 8 IJM). Results showed that MDHB significantly promoted neurite outgrowth and microtubule-a...Cerebral cortical neurons from neonatal rats were cultured in the presence of methyl 3,4-dihydroxybenzoate (MDHB; 2, 4, and 8 IJM). Results showed that MDHB significantly promoted neurite outgrowth and microtubule-associated protein 2 mRNA expression, and increased neuronal survival in a dose-dependent manner. Moreover, MDHB induced brain-derived neurotrophic factor expression. These findings suggest that MDHB has a neurotrophic effect, which may be due to its ability to increase brain-derived neurotrophic factor expression.展开更多
Myelin-associated glycoprotein(MAG) inhibits the growth of neurites from nerve cells. Extraction and purification of MAG require complex operations; therefore, we attempted to determine whether commercially availabl...Myelin-associated glycoprotein(MAG) inhibits the growth of neurites from nerve cells. Extraction and purification of MAG require complex operations; therefore, we attempted to determine whether commercially available MAG-Fc can replace endogenous MAG for research purposes. Immunofluorescence using specific antibodies against MAG, Nogo receptor(NgR) and paired immunoglobulin-like receptor B(PirB) was used to determine whether MAG-Fc can be endocytosed by neuro-2a cells. In addition, neurite outgrowth of neuro-2a cells treated with different doses of MAG-Fc was evaluated. Enzyme linked immunosorbent assays were used to measure RhoA activity. Western blot assays were conducted to assess Rho-associated protein kinase(ROCK) phosphorylation. Neuro-2a cells expressed NgR and PirB, and MAG-Fc could be endocytosed by binding to NgR and PirB. This activated intracellular signaling pathways to increase RhoA activity and ROCK phosphorylation, ultimately inhibiting neurite outgrowth. These findings not only verify that MAG-Fc can inhibit the growth of neural neurites by activating RhoA signaling pathways, similarly to endogenous MAG, but also clearly demonstrate that commercial MAG-Fc is suitable for experimental studies of neurite outgrowth.展开更多
Short-term, low-frequency electrical stimulation of neural tissues significantly enhances axonal regeneration of peripheral nerves following injury. However, little is known about the mechanisms of electrical stimulat...Short-term, low-frequency electrical stimulation of neural tissues significantly enhances axonal regeneration of peripheral nerves following injury. However, little is known about the mechanisms of electrical stimulation to induce neurite outgrowth. In the present study, short-term, low-frequency electrical stimulation, using identical stimulation parameters of in vivo experiments, was administered to in vitro dorsal root ganglion (DRG) neurons. Enhanced neurite outgrowth, as well as synthesis and release of brain-derived neurotrophic factor (BDNF), were examined in electrical stimulation-treated DRG neuronal cultures. Because the effects of electrical stimulation on neuronal intracellular signaling molecules are less reported, classic calcium intracellular signals are directly or indirectly involved in electrical stimulation effects on neurons. Cultured DRG neurons were pretreated with the calcium channel blocker nifedipine, followed by electrical stimulation. Results suggested that electrical stimulation not only promoted in vitro neurite outgrowth, but also enhanced BDNF expression. However, nifedipine reduced electrical stimulation-enhanced neurite outgrowth and BDNF biosynthesis. These results suggest that the promoting effects of electrical stimulation on DRG neurite outgrowth could be associated with altered calcium influx, which is involved induction of neuronal BDNF expression and secretion.展开更多
The dynamic assembly of microtubules plays a key role in maintaining structural and functional integrity of eukaryotic cel s,especial y with regard to neuronal differentiation or neurite outgrowth and synaptic plastic...The dynamic assembly of microtubules plays a key role in maintaining structural and functional integrity of eukaryotic cel s,especial y with regard to neuronal differentiation or neurite outgrowth and synaptic plasticity,which contribute to the development of the nervous system and memory formation.展开更多
Valproic acid (VPA) has been a first-choice drug for clinical treatment of epilepsy and manic disorder. For decades, its phar- macological action was believed to act on inhibition of gam- ma-aminobutyric acid (GABA...Valproic acid (VPA) has been a first-choice drug for clinical treatment of epilepsy and manic disorder. For decades, its phar- macological action was believed to act on inhibition of gam- ma-aminobutyric acid (GABA) transaminase, in turn, increas- ing GABA in inhibitory synapses. However, in recent years, VPA has been investigated on other therapeutic actions. Those investigations demonstrate that VPA shows neuroprotective ef- fects by promoting neurogenesis, neuronal differentiation, and neuroregeneration (Foti et al., 2013).展开更多
Inflammation is a critical pathophysiological process that modulates neuronal survival in the central nervous system after disease or injury.However,the effects and mechanisms of macrophage activation on neuronal surv...Inflammation is a critical pathophysiological process that modulates neuronal survival in the central nervous system after disease or injury.However,the effects and mechanisms of macrophage activation on neuronal survival remain unclear.In the present study,we co-cultured adult Fischer rat retinas with primary peritoneal macrophages or zymosan-treated peritoneal macrophages for 7 days.Immunofluorescence analysis revealed that peritoneal macrophages reduced retinal ganglion cell survival and neurite outgrowth in the retinal explant compared with the control group.The addition of zymosan to peritoneal macrophages attenuated the survival and neurite outgrowth of retinal ganglion cells.Conditioned media from peritoneal macrophages also reduced retinal ganglion cell survival and neurite outgrowth.This result suggests that secretions from peritoneal macrophages mediate the inhibitory effects of these macrophages.In addition,increased inflammationand oxidation-related gene expression may be related to the enhanced retinal ganglion cell degeneration caused by zymosan activation.In summary,this study revealed that primary rat peritoneal macrophages attenuated retinal ganglion cell survival and neurite outgrowth,and that macrophage activation further aggravated retinal ganglion cell degeneration.This study was approved by the Animal Ethics Committee of the Joint Shantou International Eye Center of Shantou University and the Chinese University of Hong Kong,Shantou,Guangdong Province,China,on March 11,2014(approval no.EC20140311(2)-P01).展开更多
Roles of Keap1-Nrf2 pathway in brain:Neuronal survival and neurogenesis are impaired in neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease(Winner et al.,2011).Genetic up-regulation of ...Roles of Keap1-Nrf2 pathway in brain:Neuronal survival and neurogenesis are impaired in neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease(Winner et al.,2011).Genetic up-regulation of growth factors enhanced neuronal survival and neurogenesis.展开更多
Axonal and dendritic outgrowth are fundamental processes in the development of the nervous system.During this period neurons change their morphology from a simple bipolar shape into a mature complex shape.Neurons deve...Axonal and dendritic outgrowth are fundamental processes in the development of the nervous system.During this period neurons change their morphology from a simple bipolar shape into a mature complex shape.Neurons develop dendrites and extend long or short axons that travel through a complex path until reaching target cells and form functional and accurate neuronal circuits.展开更多
Background: We have been searching effective compounds that can stimulate the growth and differentiation of nerve cells. We found previously that fulleren derivatives enhanced induction of morphological differentiatio...Background: We have been searching effective compounds that can stimulate the growth and differentiation of nerve cells. We found previously that fulleren derivatives enhanced induction of morphological differentiation with neurite outgrowth in nerve growth factor (NGF)-treated PC12 cells. In the course of our further search for other effective compounds, we found the aged garlic extract (AGE) has the activity similar to fulleren. Methods: PC12 cells were used to examine the effectiveness of test compound. Results: AGE enhanced the stimulating effect of NGF to induce morphological differentiation with neurite outgrowth in PC12 cells. In order to examine the active constituents of AGE, it was fractionated into several components. The activity was mainly localized in the F1 fraction that contains low molecular weight polar compounds. S-Allymercaptocysteine (SAMC) is one of the sulfur components of AGE present in F1 fraction and found to exhibit the enhancing effect similar to AGE. Conclusion: AGE had the ability to induce morphological differentiation with neurite outgrowth in NGF-treated PC12 cell and SAMC was one of its active constituents.展开更多
The brain is the third largest organ in the human body and consists of over80 billion neurons(Herculano-Houzel,2009).Neurons are interconnected by neurite to form a complex neural network that allows the communicati...The brain is the third largest organ in the human body and consists of over80 billion neurons(Herculano-Houzel,2009).Neurons are interconnected by neurite to form a complex neural network that allows the communication of neurons to regulate different body functions and activities.Neurites,body.展开更多
GIT1,a G-protein-coupled receptor kinase interacting protein,has been reported to be involved in neurite outgrowth.However,the neurobiological functions of the protein remain unclear.In this study,we found that GIT1 w...GIT1,a G-protein-coupled receptor kinase interacting protein,has been reported to be involved in neurite outgrowth.However,the neurobiological functions of the protein remain unclear.In this study,we found that GIT1 was highly expressed in the nervous system,and its expression was maintained throughout all stages of neuritogenesis in the brain.In primary cultured mouse hippocampal neurons from GIT1 knockout mice,there was a significant reduction in total neurite length per neuron,as well as in the average length of axon-like structures,which could not be prevented by nerve growth factor treatment.Overexpression of GIT1 significantly promoted axon growth and fully rescued the axon outgrowth defect in the primary hippocampal neuron cultures from GIT1 knockout mice.The GIT1 N terminal region,including the ADP ribosylation factor-GTPase activating protein domain,the ankyrin domains and the Spa2 homology domain,were sufficient to enhance axonal extension.Importantly,GIT1 bound to many tubulin proteins and microtubule-associated proteins,and it accelerated microtubule assembly in vitro.Collectively,our findings suggest that GIT1 promotes neurite outgrowth,at least partially by stimulating microtubule assembly.This study provides new insight into the cellular and molecular pathogenesis of GIT1-associated neurological diseases.展开更多
We introduce a direct method for transferring arrays of GaAs microtubes from an opaque substrate to a transparent glass substrate in a controlled manner. This enables us to build a platform for optical readout of the ...We introduce a direct method for transferring arrays of GaAs microtubes from an opaque substrate to a transparent glass substrate in a controlled manner. This enables us to build a platform for optical readout of the microtubes’ interaction with overgrown cellular networks. We achieve this by applying a double layer of polydimethylsiloxane (PDMS). The first PDMS layer serves as a smooth and mechanically compliant transparent substrate. The second, adhesive layer contains a mixture of PDMS and n-hexane, which creates a layer thickness smaller than the tube diameter. This will prevent the tubes from sinking into the substrate. The microtubes themselves are made of GaAs heterostructures. The direct bandgap of the material allows for the integration of embedded optical device components into the tube wall. The microtubes have diameters on the same scale as typical mouse cortical axons, being on average 1 μm. The axons can be grown through the tubes, hence maximally enhancing the capacitive coupling of the signal source (axon) and the electrode (tube). Although the tube material is toxic to cells, we are able to overcome this by a parylene-coating step.展开更多
基金supported by grants from the National Natural Science Foundation of China,No.30971531,81070987
文摘Ginsenoside Rb1 has been reported to exert anti-aging and anti-neurodegenerative effects. In the present study, we investigate whether ginsenoside Rb1 is involved in neurite outgrowth and neuroprotection against damage induced by amyloid beta(25–35) in cultured hippocampal neurons, and explore the underlying mechanisms. Ginsenoside Rb1 significantly increased neurite outgrowth in hippocampal neurons, and increased the expression of phosphorylated-Akt and phosphorylated extracellular signal-regulated kinase 1/2. These effects were abrogated by API-2 and PD98059, inhibitors of the signaling proteins Akt and MEK. Additionally, cultured hippocampal neurons were exposed to amyloid beta(25–35) for 30 minutes; ginsenoside Rb1 prevented apoptosis induced by amyloid beta(25–35), and this effect was blocked by API-2 and PD98059. Furthermore, ginsenoside Rb1 significantly reversed the reduction in phosphorylated-Akt and phosphorylated extracellular signal-regulated kinase 1/2 levels induced by amyloid beta(25–35), and API-2 neutralized the effect of ginsenoside Rb1. The present results indicate that ginsenoside Rb1 enhances neurite outgrowth and protects against neurotoxicity induced by amyloid beta(25–35) via a mechanism involving Akt and extracellular signal-regulated kinase 1/2 signaling.
基金financially supported by the National Program on Key Basic Research Project of China(973 Program),No.2010CB945600,2011CB965100the National Natural Science Foundation of China,No.81070987,30971531,81371213a grant from the International Science & Technology Collaboration Program,No.2011DF30010
文摘Ginsenoside Rg1(Rg1) has anti-aging and anti-neurodegenerative effects. However, the mechanisms underlying these actions remain unclear. The aim of the present study was to determine whether Rg1 affects hippocampal survival and neurite outgrowth in vitro after exposure to amyloid-beta peptide fragment 25–35(Aβ_(25–35)), and to explore whether the extracellular signal-regulated kinase(ERK) and Akt signaling pathways are involved in these biological processes. We cultured hippocampal neurons from newborn rats for 24 hours, then added Rg1 to the medium for another 24 hours, with or without pharmacological inhibitors of the mitogen-activated protein kinase(MAPK) family or Akt signaling pathways for a further 24 hours. We then immunostained the neurons for growth associated protein-43, and measured neurite length. In a separate experiment, we exposed cultured hippocampal neurons to Aβ_(25–35) for 30 minutes, before adding Rg1 for 48 hours, with or without Akt or MAPK inhibitors, and assessed neuronal survival using Hoechst 33258 staining, and phosphorylation of ERK1/2 and Akt by western blot analysis. Rg1 induced neurite outgrowth, and this effect was blocked by API-2(Akt inhibitor) and PD98059(MAPK/ERK kinase inhibitor), but not by SP600125 or SB203580(inhibitors of c-Jun N-terminal kinase and p38 MAPK, respectively). Consistent with this effect, Rg1 upregulated the phosphorylation of Akt and ERK1/2; these effects were reversed by API-2 and PD98059, respectively. In addition, Rg1 significantly reversed Aβ_(25–35)-induced apoptosis; this effect was blocked by API-2 and PD98059, but not by SP600125 or SB203580. Finally, Rg1 significantly reversed the Aβ_(25–35)-induced decrease in Akt and ERK1/2 phosphorylation, but API-2 prevented this reversal. Our results indicate that Rg1 enhances neurite outgrowth and protects against Aβ_(25–35)-induced damage, and that its mechanism may involve the activation of Akt and ERK1/2 signaling.
基金Part of this study has been supported by a grant to Dr Bayraktutan from The Dunhill Medical Trust(R459/0216)
文摘Breakdown of blood-brain barrier,formed mainly by brain microvascular endothelial cells(BMECs),represents the major cause of mortality during early phases of ischemic strokes.Hence,discovery of novel agents that can effectively replace dead or dying endothelial cells to restore blood-brain barrier integrity is of paramount importance in stroke medicine.Although endothelial progenitor cells(EPCs)represent one such agents,their rarity in peripheral blood severely limits their adequate isolation and therapeutic use for acute ischemic stroke which necessitate their ex vivo expansion and generate early EPCs and outgrowth endothelial cells(OECs)as a result.Functional analyses of these cells,in the present study,demonstrated that only OECs endocytosed DiI-labelled acetylated low-density lipoprotein and formed tubules on matrigel,prominent endothelial cell and angiogenesis markers,respectively.Further analyses by flow cytometry demonstrated that OECs expressed specific markers for sternness(CD34),immaturity(CD133)and endothelial cells(CD31)but not for hematopoietic cells(CD45).Like BMECs,OECs established an equally tight in vitro model of human BBB with astrocytes and pericytes,suggesting their capacity to form tight junctions.Ischemic injury mimicked by concurrent deprivation of oxygen and glucose(4 hours)or deprivation of oxygen and glucose followed by reperfusion(20 hours)affected both barrier integrity and function in a similar fashion as evidenced by decreases in transendothelial electrical resistance and increases in paracellular flux,respectively.Wound scratch assays comparing the vasculoreparative capacity of cells revealed that,compared to BMECs,OECs possessed a greater proliferative and directional migratory capacity.In a triple culture model of BBB established with astrocytes,pericytes and BMEC,exogenous addition of OECs effectively repaired the damage induced on endothelial layer in serum-free conditions.Taken together,these data demonstrate that OECs may effectively home to the site of vascular injury and repair the damage to maintain(neuro)vascular homeostasis during or after a cerebral ischemic injury.
基金supported by the NIH(NS53470)the Kentucky Spinal Cord and Head Injury Research Trust(#10-11A)the Department of Defense,CDMRP(SC090248/W81XWH-10-1-0778)
文摘Proteoglycans in the central nervous system play integral roles as "traffic signals" for the direction of neurite outgrowth. This attribute of proteoglycans is a major factor in regeneration of the injured central nervous system. In this review, the structures of proteoglycans and the evidence suggesting their involvement in the response following spinal cord injury are presented. The review further describes the methods routinely used to determine the effect proteoglycans have on neurite outgrowth. The effects of proteoglycans on neurite outgrowth are not completely understood as there is disagreement on what component of the molecule is interacting with growing neurites and this ambiguity is chronicled in an historical context. Finally, the most recent findings suggesting possible receptors, interactions, and sulfation patterns that may be important in eliciting the effect of proteoglycans on neurite outgrowth are discussed. A greater understanding of the proteoglycan-neurite interaction is necessary for successfully promoting regeneration in the iniured central nervous system.
基金National Natural and Science Foundations of China(No.30800090)"Xi-Bu-Zhi-Guang"project(2009-2012)from Chinese Academy of Science and the Fund of State Key Laboratory of Phytochemistry and Plant Resources in West China(P2010-ZZ012).
文摘15 compounds,including two new ones crepidatuols A(1)and B(2)were isolated from the stems of Dendrobium crepidatum.The planar structures of these compounds were elucidated by spectroscopic methods(NMR,MS,UV,and IR)and comparison with those from literatures.10 compounds were send for enhancing activities on nerve growth factor(NGF)medicated neurite outgrowth in PC12 cells and the results indicated that crepidatuol A(1),confusarin and 3-(2-acetoxy-5-methoxy)-phenylpropanol showed enhancing activities at the concentration of 10.0μM.
基金supported by the National Natural Science Foundation of China(General Program),No.30872602
文摘Spontaneous axonal regeneration of neurons does not occur after spinal cord injury because of inhibition by myelin and other inhibitory factors. Studies have demonstrated that blocking the Rho/Rho-kinase (ROCK) pathway can promote neurite outgrowth in spinal cord injury models. In the present study, we investigated neurite outgrowth and neuronal differentiation in neural stem cells from the mouse subventricular zone after inhibition of ROCK in vitro. Inhibition of ROCK with Y-27632 increased neurite length, enhanced neuronal differentiation, and upregulated the expression of two major signaling pathway effectors, phospho-Akt and phospho-mitogen-activated protein kinase, and the Hippo pathway effector YAP. These results suggest that inhibition of ROCK mediates neurite outgrowth in neural stem cells by activating the Hippo signaling pathway.
基金supported by Canadian Spinal Research Organization, No. #84831
文摘Previous studies have shown that transplanted enteric glia enhance axonal regeneration, reduce tissue damage, and promote functional recovery following spinal cord injury. However, the mechanisms by which enteric glia mediate these beneficial effects are unknown. Neurotrophic factors can promote neuronal differentiation, survival and neurite extension. We hypothesized that enteric glia may exert their protective effects against spinal cord injury partially through the secretion of neurotrophic factors. In the present study, we demonstrated that primary enteric glia cells release nerve growth factor, brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor over time with their concentrations reaching approximately 250, 100 and 50 pg/mL of culture medium respectively after 48 hours. The biological relevance of this secretion was assessed by incubating dissociated dorsal root ganglion neuronal cultures in enteric glia-conditioned medium with and/or without neutralizing antibodies to each of these proteins and evaluating the differences in neurite growth. We discovered that conditioned medium enhances neurite outgrowth in dorsal root ganglion neurons. Even though there was no detectable amount of neurotrophin-3 secretion using ELISA analysis, the neurite outgrowth effect can be attenuated by the antibody-mediated neutralization of each of the aforementioned neurotrophic factors. Therefore, enteric glia secrete nerve growth factor, brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor and neurotrophin-3 into their surrounding environment in concentrations that can cause a biological effect.
基金supported by the National Natural Science Foundation of China,No.30672450,81173037the National Program on Key Basic Research Project (973 Program),No.2011CB707500
文摘Cerebral cortical neurons from neonatal rats were cultured in the presence of methyl 3,4-dihydroxybenzoate (MDHB; 2, 4, and 8 IJM). Results showed that MDHB significantly promoted neurite outgrowth and microtubule-associated protein 2 mRNA expression, and increased neuronal survival in a dose-dependent manner. Moreover, MDHB induced brain-derived neurotrophic factor expression. These findings suggest that MDHB has a neurotrophic effect, which may be due to its ability to increase brain-derived neurotrophic factor expression.
基金supported by the National Natural Science Foundation of China,No.81171178
文摘Myelin-associated glycoprotein(MAG) inhibits the growth of neurites from nerve cells. Extraction and purification of MAG require complex operations; therefore, we attempted to determine whether commercially available MAG-Fc can replace endogenous MAG for research purposes. Immunofluorescence using specific antibodies against MAG, Nogo receptor(NgR) and paired immunoglobulin-like receptor B(PirB) was used to determine whether MAG-Fc can be endocytosed by neuro-2a cells. In addition, neurite outgrowth of neuro-2a cells treated with different doses of MAG-Fc was evaluated. Enzyme linked immunosorbent assays were used to measure RhoA activity. Western blot assays were conducted to assess Rho-associated protein kinase(ROCK) phosphorylation. Neuro-2a cells expressed NgR and PirB, and MAG-Fc could be endocytosed by binding to NgR and PirB. This activated intracellular signaling pathways to increase RhoA activity and ROCK phosphorylation, ultimately inhibiting neurite outgrowth. These findings not only verify that MAG-Fc can inhibit the growth of neural neurites by activating RhoA signaling pathways, similarly to endogenous MAG, but also clearly demonstrate that commercial MAG-Fc is suitable for experimental studies of neurite outgrowth.
基金the Shanghai Leading Academic Discipline Project,No.S30201the Doctoral Research Foundation of Nanchang University
文摘Short-term, low-frequency electrical stimulation of neural tissues significantly enhances axonal regeneration of peripheral nerves following injury. However, little is known about the mechanisms of electrical stimulation to induce neurite outgrowth. In the present study, short-term, low-frequency electrical stimulation, using identical stimulation parameters of in vivo experiments, was administered to in vitro dorsal root ganglion (DRG) neurons. Enhanced neurite outgrowth, as well as synthesis and release of brain-derived neurotrophic factor (BDNF), were examined in electrical stimulation-treated DRG neuronal cultures. Because the effects of electrical stimulation on neuronal intracellular signaling molecules are less reported, classic calcium intracellular signals are directly or indirectly involved in electrical stimulation effects on neurons. Cultured DRG neurons were pretreated with the calcium channel blocker nifedipine, followed by electrical stimulation. Results suggested that electrical stimulation not only promoted in vitro neurite outgrowth, but also enhanced BDNF expression. However, nifedipine reduced electrical stimulation-enhanced neurite outgrowth and BDNF biosynthesis. These results suggest that the promoting effects of electrical stimulation on DRG neurite outgrowth could be associated with altered calcium influx, which is involved induction of neuronal BDNF expression and secretion.
基金supported by the National Science Foundation of China[31870333]the Taishan Scholar Program of Shandong Province[tshw201502046]+3 种基金Shandong Provincial Science Foundation[ZR2019MH094]Yantai ShuangBai Scholar ProgramQinghai Province Applied Basic Research Project[2020-ZJ-905]the Open Project of State Key Laboratory of Plateau Ecology and Agriculture,Qinghai University[2018-KF-05]。
文摘The dynamic assembly of microtubules plays a key role in maintaining structural and functional integrity of eukaryotic cel s,especial y with regard to neuronal differentiation or neurite outgrowth and synaptic plasticity,which contribute to the development of the nervous system and memory formation.
基金supported by the Agency for Science and Technology(A*STAR)intramural funding for the Integrative Neuroscience Programme,Singapore Institute for Clinical Sciences
文摘Valproic acid (VPA) has been a first-choice drug for clinical treatment of epilepsy and manic disorder. For decades, its phar- macological action was believed to act on inhibition of gam- ma-aminobutyric acid (GABA) transaminase, in turn, increas- ing GABA in inhibitory synapses. However, in recent years, VPA has been investigated on other therapeutic actions. Those investigations demonstrate that VPA shows neuroprotective ef- fects by promoting neurogenesis, neuronal differentiation, and neuroregeneration (Foti et al., 2013).
基金supported by the National Natural Science Foundation of China,No.81570849(to LPC)the Natural Science Foundation of Guangdong Province of China,No.2020A1515010415(to LPC)+1 种基金the Special Fund for Chinese Medicine Development of Guangdong Province of China,No.20202089(to TKN)the Grant for Key Disciplinary Project of Clinical Medicine under the Guangdong High-Level University Development Program,No.002-18119101.
文摘Inflammation is a critical pathophysiological process that modulates neuronal survival in the central nervous system after disease or injury.However,the effects and mechanisms of macrophage activation on neuronal survival remain unclear.In the present study,we co-cultured adult Fischer rat retinas with primary peritoneal macrophages or zymosan-treated peritoneal macrophages for 7 days.Immunofluorescence analysis revealed that peritoneal macrophages reduced retinal ganglion cell survival and neurite outgrowth in the retinal explant compared with the control group.The addition of zymosan to peritoneal macrophages attenuated the survival and neurite outgrowth of retinal ganglion cells.Conditioned media from peritoneal macrophages also reduced retinal ganglion cell survival and neurite outgrowth.This result suggests that secretions from peritoneal macrophages mediate the inhibitory effects of these macrophages.In addition,increased inflammationand oxidation-related gene expression may be related to the enhanced retinal ganglion cell degeneration caused by zymosan activation.In summary,this study revealed that primary rat peritoneal macrophages attenuated retinal ganglion cell survival and neurite outgrowth,and that macrophage activation further aggravated retinal ganglion cell degeneration.This study was approved by the Animal Ethics Committee of the Joint Shantou International Eye Center of Shantou University and the Chinese University of Hong Kong,Shantou,Guangdong Province,China,on March 11,2014(approval no.EC20140311(2)-P01).
基金supported by the following grants to JHR:General Research Fund(GRF)(HKU 775812M)from the Research Grants Council of Hong Kongthe Seed Fund for Basic Research ProgramThe University of Hong Kong
文摘Roles of Keap1-Nrf2 pathway in brain:Neuronal survival and neurogenesis are impaired in neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease(Winner et al.,2011).Genetic up-regulation of growth factors enhanced neuronal survival and neurogenesis.
基金supported by Fundacao para a Ciência e a Tecnologia(FCT)Grants:PTDC/SAU-NEU/64126/2006,FCOMP-01-0124-FEDER-017455(HMSP-ICT/0020/2010),EXPL/BIMMEC/0009/2013,PortugalFilipa F Ribeiro was in receipt of a fellowship(SFRH/BD/74662/2010)from FCT
文摘Axonal and dendritic outgrowth are fundamental processes in the development of the nervous system.During this period neurons change their morphology from a simple bipolar shape into a mature complex shape.Neurons develop dendrites and extend long or short axons that travel through a complex path until reaching target cells and form functional and accurate neuronal circuits.
文摘Background: We have been searching effective compounds that can stimulate the growth and differentiation of nerve cells. We found previously that fulleren derivatives enhanced induction of morphological differentiation with neurite outgrowth in nerve growth factor (NGF)-treated PC12 cells. In the course of our further search for other effective compounds, we found the aged garlic extract (AGE) has the activity similar to fulleren. Methods: PC12 cells were used to examine the effectiveness of test compound. Results: AGE enhanced the stimulating effect of NGF to induce morphological differentiation with neurite outgrowth in PC12 cells. In order to examine the active constituents of AGE, it was fractionated into several components. The activity was mainly localized in the F1 fraction that contains low molecular weight polar compounds. S-Allymercaptocysteine (SAMC) is one of the sulfur components of AGE present in F1 fraction and found to exhibit the enhancing effect similar to AGE. Conclusion: AGE had the ability to induce morphological differentiation with neurite outgrowth in NGF-treated PC12 cell and SAMC was one of its active constituents.
基金supported by funds from the Research Grants Council Hong KongHealth and Medical Research Fund(Hong Kong)+2 种基金the Chinese University of Hong Kong(CUHK) direct grant schemethe United College endowment fundthe TUYF Charitable Trust
文摘The brain is the third largest organ in the human body and consists of over80 billion neurons(Herculano-Houzel,2009).Neurons are interconnected by neurite to form a complex neural network that allows the communication of neurons to regulate different body functions and activities.Neurites,body.
基金supported by the grants to HLS from the National Natural Science Foundation of China(81371507)Medicine and Engineering Cross-talking Funds of Shanghai Jiao Tong University(YG2013MS40)+8 种基金Science and Technology Projects of Shanghai Jiao Tong University Medical School(13XJ10016)the National Basic Research Program of China(973 Program2013CB945600)by the grants to WQG from the Chinese Ministry of Science and Technology(2012CB966800 and 2013CB945600)the National Natural Science Foundation of China(81130038 and 81372189)the Science and Technology Commission of Shanghai Municipality(Pujiang Program)the Shanghai Health Bureau Key Disciplines and Specialties Foundationthe Shanghai Education Committee Key Discipline and Specialties Foundation(J50208)KC Wong Foundation
文摘GIT1,a G-protein-coupled receptor kinase interacting protein,has been reported to be involved in neurite outgrowth.However,the neurobiological functions of the protein remain unclear.In this study,we found that GIT1 was highly expressed in the nervous system,and its expression was maintained throughout all stages of neuritogenesis in the brain.In primary cultured mouse hippocampal neurons from GIT1 knockout mice,there was a significant reduction in total neurite length per neuron,as well as in the average length of axon-like structures,which could not be prevented by nerve growth factor treatment.Overexpression of GIT1 significantly promoted axon growth and fully rescued the axon outgrowth defect in the primary hippocampal neuron cultures from GIT1 knockout mice.The GIT1 N terminal region,including the ADP ribosylation factor-GTPase activating protein domain,the ankyrin domains and the Spa2 homology domain,were sufficient to enhance axonal extension.Importantly,GIT1 bound to many tubulin proteins and microtubule-associated proteins,and it accelerated microtubule assembly in vitro.Collectively,our findings suggest that GIT1 promotes neurite outgrowth,at least partially by stimulating microtubule assembly.This study provides new insight into the cellular and molecular pathogenesis of GIT1-associated neurological diseases.
基金We would like to thank the the Air Force Office of Scientific Research(AFOSR)for support through the MURI and the DFG for funding by grant HA2042/6-1 and GrK1286.
文摘We introduce a direct method for transferring arrays of GaAs microtubes from an opaque substrate to a transparent glass substrate in a controlled manner. This enables us to build a platform for optical readout of the microtubes’ interaction with overgrown cellular networks. We achieve this by applying a double layer of polydimethylsiloxane (PDMS). The first PDMS layer serves as a smooth and mechanically compliant transparent substrate. The second, adhesive layer contains a mixture of PDMS and n-hexane, which creates a layer thickness smaller than the tube diameter. This will prevent the tubes from sinking into the substrate. The microtubes themselves are made of GaAs heterostructures. The direct bandgap of the material allows for the integration of embedded optical device components into the tube wall. The microtubes have diameters on the same scale as typical mouse cortical axons, being on average 1 μm. The axons can be grown through the tubes, hence maximally enhancing the capacitive coupling of the signal source (axon) and the electrode (tube). Although the tube material is toxic to cells, we are able to overcome this by a parylene-coating step.