BACKGROUND： Previous studies have shown that p75 neurotrophin receptor plays an important role in peripheral nerve injury. However, the role of p75 neurotrophin receptor in the regeneration of peripheral nerves remai...BACKGROUND： Previous studies have shown that p75 neurotrophin receptor plays an important role in peripheral nerve injury. However, the role of p75 neurotrophin receptor in the regeneration of peripheral nerves remains poorly understood. OBJECTIVE： To study the effect of p75 neurotrophin receptor on facial nerve regeneration. DESIGN, TIME AND SETTING： A randomized controlled experiment was performed in the Regeneration Laboratory of Flinders University, Australia and the Biomedical Laboratory of Dentistry School, Shandong University from March 2005 to February 2006. MATERIALS： Cholera toxin B subunit, fast blue, and biotin rabbit-anti goat IgG were provided by Sigma, USA; goat-anti choleratoxin B subunit ant/body was provided by List Biologicals, USA. METHODS： In p75 neurotrophin receptor knockout and wild type 129/sv mice, the facial nerves on one side were crushed. At days 2 and 4 following injury, regenerating motor neurons in the facial nuclei were labeled by fast blue, and the regenerating axon was labeled by the anterograde tracer choleratoxin B subunit. MAIN OUTCOME MEASURES： Axonal regenerative velocity and number were detected by immunohistochemical staining of choleratoxin B subunit, growth-associated protein, protein gene product 9.5, and calcitonin-gene-related peptide; survival of motor neurons in the facial nuclei was detected by retrograde fast blue. RESULTS： Axonal growth in the facial nerve of p75 neurotrophin receptor knockout mice was significantly less than in wild type mice. At day 7 after injury, the number of regenerating motor neurons in p75 neurotrophin receptor knockout mice remained significantly less than in wild type mice （P 〈 0.05）. The number of positively stained fibers for growth-associated protein-43, protein gene product 9.5, and calcitonin-gene-related peptide in p75 neurotrophin receptor knockout mice was significantly less than in wild type mice （P 〈 0.01）. CONCLUSION： p75 neurotrophin receptor promoted axonal regeneration and enhanced the survival rate of motor neurons following facial nerve injury.展开更多
BACKGROUND： Studies have demonstrated that cauda equina compression results in apoptosis of motor neurons in the spinal cord. The combination of p75 neurotrophin receptor （p75NTR） and precursor of nerve growth fact...BACKGROUND： Studies have demonstrated that cauda equina compression results in apoptosis of motor neurons in the spinal cord. The combination of p75 neurotrophin receptor （p75NTR） and precursor of nerve growth factor （pro-NGF） expression initiates the apoptotic pathway and induces neuronal apoptosis. However, few reports have focused on the p75-mediated mechanism of neuronal apoptosis following cauda equine compression injury OBJECTIVE： To determine apoptosis of spinal cord neurons and activation of the pro-NGF-p75NTR-JNK（c-Jun N-terminal kinase） signal pathway in rats following cauda equina compression, and to verify experimental outcomes. DESIGN, TIME AND SETTING： A randomized, controlled, in vivo experiment was performed at the Medical Experimental Center of Xi＇an Jiaotong University between April and November in 2008. MATERIALS： Streptavidin-perosidase kit was purchased from Wuhan Boster, China; in situ end labeling detection kit was provided by Promega, USA; type AEG-220G electron microscope was purchased from Hitachi, Japan. METHODS： A total of 48 healthy, adult, female, Sprague Dawley rats were randomly assigned to three groups： normal （n = 6）, sham-surgery （n = 6）, and compression （n = 36）. The compression group was randomly assigned to six subsets at 1,3, 5, 7, 14, and 28 days, respectively, with 6 rats in each subset. A cylindrical silica gel stick was implanted into the rats to compress 75% of the vertebral canal in the compression group; in the sham-surgery group, only vertebral resection was performed; and no procedures were performed in the normal group. MAIN OUTCOME MEASURES： At 1,3, 5, 7, 14, and 28 days following compression, L2-3 spinal cord segments were processed for immunohistochemistry, in situ cell apoptosis detection, and transmission electron microscopy observation. Nissl staining was used to observe neuronal survival in the L2 spinal cord segment. Immunohistochemistry was applied to detect expressions of pro-NGF, p75NTR, and JNK in the L2 segment. TUNEL fluorometric method was used to observe apoptosis of neurons in the L2 segment. RESULTS： In the normal and sham-surgery groups, little neuronal apoptosis was observed in the L2-3 spinal cord segment. At 3 days after compression injury, pro-NGF, p75NTR and JNK expression was observed in the spinal cord. Expression levels reached a peak at 7 days, and then gradually decreased. In the compression and sham-surgery groups, neurons primarily expressed pro-NGF and p75NTR. The number of JNK-positive neurons in the compression group was dramatically increased compared with the sham-surgery group （P〈 0.05）. A few neurons were apoptotic in the spinal cord 1 day after compression injury. The number of apoptotic neurons gradually increased and reached a peak at 7 days, and subsequently decreased. Apoptosis was still detectable at 28 days. There was a positive correlation between p75NTR expression and neuronal apoptosis （r= 0.75, P〈 0.05）. CONCLUSION： Following cauda equina compression injury, apoptosis of spinal cord neurons was observed. The compression-induced neuronal apoptosis was associated with p75NTR expression in the L2-3 spinal cord segment.展开更多
This study demonstrated that brain areas surrounding the site of hematoma following intracerebral hemorrhage are characterized by significantly increased apoptosis and expression of neurotrophin receptor p75 and sorti...This study demonstrated that brain areas surrounding the site of hematoma following intracerebral hemorrhage are characterized by significantly increased apoptosis and expression of neurotrophin receptor p75 and sortilin. However, as detected by terminal deoxynucleotidyl transferase dUTP nick end labeling and immunohistochemical staining, there was no significant change in nerve growth factor precursor expression levels. The appearance of neurotrophin receptor p75 expressing cells was positively correlated with cells that were detected by terminal deoxynucleotidyl transferase dUTP nick end labeling. These findings confirm that the nerve growth factor precursor-neurotrophin receptor p75-sortilin heterotrimeric complex-mediated apoptosis pathway may play an important role in cellular apoptosis following intracerebral hemorrhage.展开更多
Previous studies have confirmed that motor neuron apoptosis in the anterior horn of the lumbosacral spinal cord is positively correlated with p75 neurotrophin receptor （p75NTR） expression in rat models of cauda equi...Previous studies have confirmed that motor neuron apoptosis in the anterior horn of the lumbosacral spinal cord is positively correlated with p75 neurotrophin receptor （p75NTR） expression in rat models of cauda equina syndrome. This study used adenovirus to carry a short hairpin RNA （shRNA） for p75NTR gene silencing, to reduce p75NTR expression in the damaged phase and to decrease motor neuron apoptosis. Three p75 siRNA template oligonucleotide segments （shRNA） were designed, and cloned into the 1.0 CMV shuttle vector. HEK293 cells were cotransfected with shuttle vector （carrying shRNA） and an adenovirus vector framework expressing enhanced green fluorescent protein. Thus, this study successfully obtained adenovirus carrying p75shRNA. The obtained viruses were named Ad.shRNA1, Ad.shRNA2, and Ad.shRNA3. The recombinant adenoviruses were separately used to infect cultured pheochromocytoma cells （PC12）. Forty-eight hours later, p75NTR mRNA and total protein were analyzed from the PC12 cells. Compared with the negative controls, RNA interference rates were separately 98.49 ± 0.68%, 95.08 ± 1.79% and 96.60 ± 1.14% at the mRNA level, and 72.89 ± 2.17%, 58.83 ± 1.15% and 59.88 ± 0.44% at the protein level in the Ad.shRNA1, Ad.shRNA2, and Ad.shRNA3 groups, respectively. Thus, recombinant adenovirus shRNA-mediated gene silencing successfully suppressed p75NTR expression.展开更多
The p75 neurotrophin receptor, which is a member of the tumor necrosis factor receptor superfamil facilitates apoptosis during development and following central nervous system injury. Previous studies have shown that ...The p75 neurotrophin receptor, which is a member of the tumor necrosis factor receptor superfamil facilitates apoptosis during development and following central nervous system injury. Previous studies have shown that programmed cell death is likely involved in the neurotoxic effects of 3, 4-methylenedioxy-N-methylamphetamine （MDMA）, because MDMA induces apoptosis of immortalized neurons through regulation of proteins belonging to the Bcl-2 family. In the present study, intrapedtoneal injection of different doses of MDMA （20, 50, and 100 mg/kg） induced significant behavioral changes, such as increased excitability, increased activity, and irritability in rats. Moreover, changes exhibited dose-dependent adaptation. Following MDMA injection in rat brain tissue, the number of apoptotic cells dose-dependently increased and p75 neurotrophin receptor expression significantly increased in the prefrontal cortex, cerebellum, and hippocampus. These findings confirmed that MDMA induced neuronal apoptosis, and results suggested that this effect was related by upregulated protein expression of the p75 neurotrophin receptor.展开更多
Animal models of intracerebral hemorrhage were established by injection of autologous blood into the caudate nucleus in rats. Cell apoptosis was measured by flow cytometry and immunohistochemical staining of the p75 n...Animal models of intracerebral hemorrhage were established by injection of autologous blood into the caudate nucleus in rats. Cell apoptosis was measured by flow cytometry and immunohistochemical staining of the p75 neurotrophin receptor. p75 neurotrophin receptor protein was detected by immunohistochemistry. p75 neurotrophin receptor mRNA was examined by quantitative real-time polymerase chain reactions. At 24 hours after modeling, cellular apoptosis occured around hematoma with upregulation of p75 neurotrophin receptor protein and mRNA was observed, which directly correlated to apoptosis. This observation indicated that p75 neurotrophin receptor upregulation was associated with cell apoptosis around hematomas after intracerebral hemorrhage.展开更多
Neurodegenerative diseases and neural injury are 2 of the most feared disorders that afflict humankind by leading to permanent paralysis and loss of sensation.Cell based treatment for these diseases had gained special...Neurodegenerative diseases and neural injury are 2 of the most feared disorders that afflict humankind by leading to permanent paralysis and loss of sensation.Cell based treatment for these diseases had gained special interest in recent years.Previous studies showed that dental pulp stem cells(DPSCs) could differentiate toward functionally active neurons both in vitro and in vivo,and could promote neuranagenesis through both cell-autonomous and paracrine neuroregenerative activities.Some of these neuroregenerative activities were unique to tooth-derived stem cells and superior to bone marrow stromal cells.However,DPSCs used in most of these studies were mixed and unfractionated dental pulp cells that contain several types of cells,and most were fibroblast cells while just contain a small portion of DPSCs.Thus,there might be weaker ability of neuranagenesis and more side effects from the fibroblast cells that cannot differentiate into neural cells.p75 neurotrophin receptor(p75 NTR) positive DPSCs subpopulation was derived from migrating cranial neural crest cells and had been isolated from DPSCs,which had capacity of differentiation into neurons and repairing neural system.In this article,we hypothesize that p75 NTR positive DPSCs simultaneously have greater propensity for neuronal differentiation and fewer side effects from fibroblast,and in vivo transptantation of autologous p75 NTR positive DPSCs is a novel method for neuranagenesis.This will bring great hope to patients with neurodegenerative disease and neural injury.Supported by Key Basic Research Fund of Science and Technology Commission of Shanghai Municipality(10JC1408700).展开更多
Background By unbiased stereological methods, we have observed preferential dorsal root ganglion （DRG） B-cell loss in rodents after nerve injury, and caspase-3 activation and cell loss were related to the present of...Background By unbiased stereological methods, we have observed preferential dorsal root ganglion （DRG） B-cell loss in rodents after nerve injury, and caspase-3 activation and cell loss were related to the present of p75 receptor （p75^NTR）. We hypothesized that DRG B-cells express higher levels of pro-apoptotic proteins as compared to A-cells and the expressions of pro-apoptotic proteins can be reduced by depletion of p75^NTR. This study aimed to identify the p75NTR involved apoptotic pathway in DRG neurons after nerve injury. Methods The p75NTR knockout mice （p75-/-） and wildtype Balb/C mice （p75＋/＋） were used in this study. The expressions of pro-apoptotic proteins, c-Jun-N-terminal kinase （JNK）, c-jun and p38 in DRG were evaluated with immunohistochemistry 2 and 7 days following unilateral sciatic nerve transection. In addition, extra-cellular related kinase （ERK）, a transducer of survival signals, was also tested with immunohistochemistry and Western blotting methods in these animal models. Results Phosphorylated JNK （P-JNK） and phosphorylated p38 （P-p38） were mainly located in small B-cells, whereas phosphorylated c-jun （P-c-jun） was located in both A- and B-cells. Phosphorylated ERK （P-ERK） was located in both B-cells and satellite cells. Axotomy dramatically increased the expressions of P-JNK and P-c-jun （paired t-test）, with no influence on the expressions of P-p38 and P-ERK. Furthermore, the increase of P-JNK in p75＋/＋ mice 2 days after nerve axotomy was approximately 2.2-folds of that in p75-/- mice （P=-0.001, unpaired t-test）. Conclusion p75NTR-dependent JNK-caspase-3 pathway is involved in DRG B-cell loss after nerve injury and JNK is not the unique upstream of c-jun activation.展开更多
Axonal growth inhibitors are released during traumatic injuries to the adult mammalian central nervous system, including after spinal cord injury. These molecules accumulate at the injury site and form a highly inhibi...Axonal growth inhibitors are released during traumatic injuries to the adult mammalian central nervous system, including after spinal cord injury. These molecules accumulate at the injury site and form a highly inhibitory environment for axonal regeneration. Among these inhibitory molecules, myelinassociated inhibitors, including neurite outgrowth inhibitor A, oligodendrocyte myelin glycoprotein, myelin-associated glycoprotein, chondroitin sulfate proteoglycans and repulsive guidance molecule A are of particular importance. Due to their inhibitory nature, they represent exciting molecular targets to study axonal inhibition and regeneration after central injuries. These molecules are mainly produced by neurons, oligodendrocytes, and astrocytes within the scar and in its immediate vicinity. They exert their effects by binding to specific receptors, localized in the membranes of neurons. Receptors for these inhibitory cues include Nogo receptor 1, leucine-rich repeat, and Ig domain containing 1 and p75 neurotrophin receptor/tumor necrosis factor receptor superfamily member 19(that form a receptor complex that binds all myelin-associated inhibitors), and also paired immunoglobulin-like receptor B. Chondroitin sulfate proteoglycans and repulsive guidance molecule A bind to Nogo receptor 1, Nogo receptor 3, receptor protein tyrosine phosphatase σ and leucocyte common antigen related phosphatase, and neogenin, respectively. Once activated, these receptors initiate downstream signaling pathways, the most common amongst them being the Rho A/ROCK signaling pathway. These signaling cascades result in actin depolymerization, neurite outgrowth inhibition, and failure to regenerate after spinal cord injury. Currently, there are no approved pharmacological treatments to overcome spinal cord injuries other than physical rehabilitation and management of the array of symptoms brought on by spinal cord injuries. However, several novel therapies aiming to modulate these inhibitory proteins and/or their receptors are under investigation in ongoing clinical trials. Investigation has also been demonstrating that combinatorial therapies of growth inhibitors with other therapies, such as growth factors or stem-cell therapies, produce stronger results and their potential application in the clinics opens new venues in spinal cord injury treatment.展开更多
Peripheral neuropathy is a condition where damage resulting from mechanical or pathological mechanisms is inflicted on nerves within the peripheral nervous system （PNS）. Physical injury is the most common cause and ...Peripheral neuropathy is a condition where damage resulting from mechanical or pathological mechanisms is inflicted on nerves within the peripheral nervous system （PNS）. Physical injury is the most common cause and may result in nerves being partially or completely severed, crushed, compressed or stretched. Other causes include metabolic or endocrine disorders, with e.g.,展开更多
We investigated nerve growth factor precursor （proNGF） and mature NGF expression in ischemic and non-ischemic cortices after cerebral ischemia-reperfusion injury. In both ischemic and non-ischemic cortices, proNGF w...We investigated nerve growth factor precursor （proNGF） and mature NGF expression in ischemic and non-ischemic cortices after cerebral ischemia-reperfusion injury. In both ischemic and non-ischemic cortices, proNGF was found to be present in the extracellular space and cytoplasm. In addition, mature NGF was expressed in extracellular space, but with a very low signal. In ischemic cortex only, proNGF was significantly decreased, reaching a minimal level at 1 day. Mature NGF was increased at 4 hours, then reached a minimal level at 3 days. The p75 neurotrophin receptor （p75NTR） was significantly decreased after ischemia, and increased at 3 days after ischemia. These results confirmed that proNGF was the predominant form of NGF during the pathological process of cerebral ischemia-repeffusion injury. In addition, our findings suggest that ischemic injury may influence the conversion of proNGF to mature NGF, and that proNGF/p75NTR may be involved in reperfusion injury.展开更多
The carotid body (CB) is a small neural crest-derived organ that registers oxygen and glucose levels in blood and regulates ventilation. The most abundant cell type in the CB glomeruli is glomus or type I cells, which...The carotid body (CB) is a small neural crest-derived organ that registers oxygen and glucose levels in blood and regulates ventilation. The most abundant cell type in the CB glomeruli is glomus or type I cells, which is enveloped by processes of sustentacular or type II cells. Growth and neurotrophic factors have been established as signaling molecules played an important role in the development of the CB. To gain insight whether these signaling molecules are present in the adult rat CB, we examined the expression and cellular localization of some neurotrophic factors and their corresponding receptors in this organ by immunohistochemistry. The results showed the presence of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF) as well as p75NTR, tyrosine kinase A receptor (TrkA), tyrosine kinase B receptor (TrkB) and GDNF family receptor alpha1 (GFRα1) in the adult CB. At the light-microscopical level, the immunoreactivity for NGF and both its low-affinity (p75) and high-affinity (TrkA) receptors was detected in the majority of glomus cells and also in a subset of sustentacular cells. BDNF and its receptors, p75 and TrkB, were observed in the glomus cells, too. Remarkably, the immunohistochemical analysis revealed that the neuron-like glomus cells, but not the glial-like sustentacular cells, expressed GDNF and GFRα1. Taken together with prior results, it can be inferred that neurotrophins may be involved in the CB cell differentiation and survival in adulthood, and may exert a potent glomic protective action as well. It is also presumable that GDNF production by glomus cells plays a pivotal role in permitting long-term viability of CB grafts, which permits their potential applicability in cell therapy as a promising tool in neurodegenerative disorders.展开更多
In psychopharmacology of depression, we observe two ways of research. One group is focused on catecholamines action. Second one fixes attention on neuronal morphogenesis and synaptic plasticity. The intimate connectio...In psychopharmacology of depression, we observe two ways of research. One group is focused on catecholamines action. Second one fixes attention on neuronal morphogenesis and synaptic plasticity. The intimate connection of astrocytes, neurons and synaptic endings determines glial participation in neural homeostasis. Consequently this situation enlarges the role of astrocytes in the CNS synaptic plasticity. Brain Derived Neurotrophic factor and its receptor TrkB suppose to coordinate both of the above mentioning signaling pathways in depression disturbances. In our experiment, we have exploited striatal tissue because in our opinion this structure is misjudged in pathophysiology of depression alas;Several hypothesis proposed striatum as important in future intention activity structure. RT-PCR analysis was used to determine D1, BDNF and TrkB mRNA expression in cultured striatal astroglial cells. Administration of three representative antidepressants (ADs) like amitriptyline, moclobemide and sertraline to astroglial culture medium increase the D1, BDNF/TrkB mRNA expression. Our previous study showed that the stimulation of cAMP to CREB pathway after D1 receptors excitation constituted a common response to ADs. The present results signify that D1, BDNF/TrkB link which is next neural track (after cAMP/PKA) involved in the CNS adaptation to external conditions altered by chronic ADs treatment. Moreover, the striatum tissue appears to be important formation which takes an active part in antidepressant action thus essential in depression disorder etiology.展开更多
β-Amyloid(Aβ)is a specific pathological hallmark of Alzheimer's disease(AD).Because of its neurotoxicity,AD patients exhibit multiple brain dysfunctions.Disease-modifying therapy(DMT)is the central concept in th...β-Amyloid(Aβ)is a specific pathological hallmark of Alzheimer's disease(AD).Because of its neurotoxicity,AD patients exhibit multiple brain dysfunctions.Disease-modifying therapy(DMT)is the central concept in the development of AD thera-peutics today,and most DMT drugs that are currently in clinical trials are anti-Aβdrugs,such as aducanumab and lecanemab.Therefore,understanding Aβ's neurotoxic mechanism is crucial for Aβ-targeted drug development.Despite its total length of only a few dozen amino acids,Aβis incredibly diverse.In addition to the well-known Aβ_(1-42),N-terminally truncated,glutaminyl cyclase(QC)catalyzed,and pyroglutamate-modified Aβ(pEAβ)is also highly amyloidogenic and far more cytotoxic.The extracel-lular monomeric Aβ_(x-42)(x=1-11)initiates the aggregation to form fibrils and plaques and causes many abnormal cellular responses through cell membrane receptors and receptor-coupled signal pathways.These signal cascades further influence many cel-lular metabolism-related processes,such as gene expression,cell cycle,and cell fate,and ultimately cause severe neural cell damage.However,endogenous cellular anti-Aβdefense processes always accompany the Aβ-induced microenvironment alterations.Aβ-cleaving endopeptidases,Aβ-degrading ubiquitin-proteasome system(UPS),and Aβ-engulfing glial cell immune responses are all essential self-defense mechanisms that we can leverage to develop new drugs.This review discusses some of the most recent advances in understanding Aβ-centric AD mechanisms and suggests prospects for promising anti-Aβstrategies.展开更多
基金the Natural Science Foundation of Shandong Province,No. Y2008C54
文摘BACKGROUND： Previous studies have shown that p75 neurotrophin receptor plays an important role in peripheral nerve injury. However, the role of p75 neurotrophin receptor in the regeneration of peripheral nerves remains poorly understood. OBJECTIVE： To study the effect of p75 neurotrophin receptor on facial nerve regeneration. DESIGN, TIME AND SETTING： A randomized controlled experiment was performed in the Regeneration Laboratory of Flinders University, Australia and the Biomedical Laboratory of Dentistry School, Shandong University from March 2005 to February 2006. MATERIALS： Cholera toxin B subunit, fast blue, and biotin rabbit-anti goat IgG were provided by Sigma, USA; goat-anti choleratoxin B subunit ant/body was provided by List Biologicals, USA. METHODS： In p75 neurotrophin receptor knockout and wild type 129/sv mice, the facial nerves on one side were crushed. At days 2 and 4 following injury, regenerating motor neurons in the facial nuclei were labeled by fast blue, and the regenerating axon was labeled by the anterograde tracer choleratoxin B subunit. MAIN OUTCOME MEASURES： Axonal regenerative velocity and number were detected by immunohistochemical staining of choleratoxin B subunit, growth-associated protein, protein gene product 9.5, and calcitonin-gene-related peptide; survival of motor neurons in the facial nuclei was detected by retrograde fast blue. RESULTS： Axonal growth in the facial nerve of p75 neurotrophin receptor knockout mice was significantly less than in wild type mice. At day 7 after injury, the number of regenerating motor neurons in p75 neurotrophin receptor knockout mice remained significantly less than in wild type mice （P 〈 0.05）. The number of positively stained fibers for growth-associated protein-43, protein gene product 9.5, and calcitonin-gene-related peptide in p75 neurotrophin receptor knockout mice was significantly less than in wild type mice （P 〈 0.01）. CONCLUSION： p75 neurotrophin receptor promoted axonal regeneration and enhanced the survival rate of motor neurons following facial nerve injury.
基金the National Natural Science Foundation of China, No. 30672136
文摘BACKGROUND： Studies have demonstrated that cauda equina compression results in apoptosis of motor neurons in the spinal cord. The combination of p75 neurotrophin receptor （p75NTR） and precursor of nerve growth factor （pro-NGF） expression initiates the apoptotic pathway and induces neuronal apoptosis. However, few reports have focused on the p75-mediated mechanism of neuronal apoptosis following cauda equine compression injury OBJECTIVE： To determine apoptosis of spinal cord neurons and activation of the pro-NGF-p75NTR-JNK（c-Jun N-terminal kinase） signal pathway in rats following cauda equina compression, and to verify experimental outcomes. DESIGN, TIME AND SETTING： A randomized, controlled, in vivo experiment was performed at the Medical Experimental Center of Xi＇an Jiaotong University between April and November in 2008. MATERIALS： Streptavidin-perosidase kit was purchased from Wuhan Boster, China; in situ end labeling detection kit was provided by Promega, USA; type AEG-220G electron microscope was purchased from Hitachi, Japan. METHODS： A total of 48 healthy, adult, female, Sprague Dawley rats were randomly assigned to three groups： normal （n = 6）, sham-surgery （n = 6）, and compression （n = 36）. The compression group was randomly assigned to six subsets at 1,3, 5, 7, 14, and 28 days, respectively, with 6 rats in each subset. A cylindrical silica gel stick was implanted into the rats to compress 75% of the vertebral canal in the compression group; in the sham-surgery group, only vertebral resection was performed; and no procedures were performed in the normal group. MAIN OUTCOME MEASURES： At 1,3, 5, 7, 14, and 28 days following compression, L2-3 spinal cord segments were processed for immunohistochemistry, in situ cell apoptosis detection, and transmission electron microscopy observation. Nissl staining was used to observe neuronal survival in the L2 spinal cord segment. Immunohistochemistry was applied to detect expressions of pro-NGF, p75NTR, and JNK in the L2 segment. TUNEL fluorometric method was used to observe apoptosis of neurons in the L2 segment. RESULTS： In the normal and sham-surgery groups, little neuronal apoptosis was observed in the L2-3 spinal cord segment. At 3 days after compression injury, pro-NGF, p75NTR and JNK expression was observed in the spinal cord. Expression levels reached a peak at 7 days, and then gradually decreased. In the compression and sham-surgery groups, neurons primarily expressed pro-NGF and p75NTR. The number of JNK-positive neurons in the compression group was dramatically increased compared with the sham-surgery group （P〈 0.05）. A few neurons were apoptotic in the spinal cord 1 day after compression injury. The number of apoptotic neurons gradually increased and reached a peak at 7 days, and subsequently decreased. Apoptosis was still detectable at 28 days. There was a positive correlation between p75NTR expression and neuronal apoptosis （r= 0.75, P〈 0.05）. CONCLUSION： Following cauda equina compression injury, apoptosis of spinal cord neurons was observed. The compression-induced neuronal apoptosis was associated with p75NTR expression in the L2-3 spinal cord segment.
基金the Science and Technology Research and Development Program of Shaanxi Province, No. 2007K15-01
文摘This study demonstrated that brain areas surrounding the site of hematoma following intracerebral hemorrhage are characterized by significantly increased apoptosis and expression of neurotrophin receptor p75 and sortilin. However, as detected by terminal deoxynucleotidyl transferase dUTP nick end labeling and immunohistochemical staining, there was no significant change in nerve growth factor precursor expression levels. The appearance of neurotrophin receptor p75 expressing cells was positively correlated with cells that were detected by terminal deoxynucleotidyl transferase dUTP nick end labeling. These findings confirm that the nerve growth factor precursor-neurotrophin receptor p75-sortilin heterotrimeric complex-mediated apoptosis pathway may play an important role in cellular apoptosis following intracerebral hemorrhage.
基金the National Natural Science Foundation of China, No. 30672136
文摘Previous studies have confirmed that motor neuron apoptosis in the anterior horn of the lumbosacral spinal cord is positively correlated with p75 neurotrophin receptor （p75NTR） expression in rat models of cauda equina syndrome. This study used adenovirus to carry a short hairpin RNA （shRNA） for p75NTR gene silencing, to reduce p75NTR expression in the damaged phase and to decrease motor neuron apoptosis. Three p75 siRNA template oligonucleotide segments （shRNA） were designed, and cloned into the 1.0 CMV shuttle vector. HEK293 cells were cotransfected with shuttle vector （carrying shRNA） and an adenovirus vector framework expressing enhanced green fluorescent protein. Thus, this study successfully obtained adenovirus carrying p75shRNA. The obtained viruses were named Ad.shRNA1, Ad.shRNA2, and Ad.shRNA3. The recombinant adenoviruses were separately used to infect cultured pheochromocytoma cells （PC12）. Forty-eight hours later, p75NTR mRNA and total protein were analyzed from the PC12 cells. Compared with the negative controls, RNA interference rates were separately 98.49 ± 0.68%, 95.08 ± 1.79% and 96.60 ± 1.14% at the mRNA level, and 72.89 ± 2.17%, 58.83 ± 1.15% and 59.88 ± 0.44% at the protein level in the Ad.shRNA1, Ad.shRNA2, and Ad.shRNA3 groups, respectively. Thus, recombinant adenovirus shRNA-mediated gene silencing successfully suppressed p75NTR expression.
基金supported by the National Natural Science Foundation of China (MDMA Neurotoxicity and Mechanism),No.C090302
文摘The p75 neurotrophin receptor, which is a member of the tumor necrosis factor receptor superfamil facilitates apoptosis during development and following central nervous system injury. Previous studies have shown that programmed cell death is likely involved in the neurotoxic effects of 3, 4-methylenedioxy-N-methylamphetamine （MDMA）, because MDMA induces apoptosis of immortalized neurons through regulation of proteins belonging to the Bcl-2 family. In the present study, intrapedtoneal injection of different doses of MDMA （20, 50, and 100 mg/kg） induced significant behavioral changes, such as increased excitability, increased activity, and irritability in rats. Moreover, changes exhibited dose-dependent adaptation. Following MDMA injection in rat brain tissue, the number of apoptotic cells dose-dependently increased and p75 neurotrophin receptor expression significantly increased in the prefrontal cortex, cerebellum, and hippocampus. These findings confirmed that MDMA induced neuronal apoptosis, and results suggested that this effect was related by upregulated protein expression of the p75 neurotrophin receptor.
文摘Animal models of intracerebral hemorrhage were established by injection of autologous blood into the caudate nucleus in rats. Cell apoptosis was measured by flow cytometry and immunohistochemical staining of the p75 neurotrophin receptor. p75 neurotrophin receptor protein was detected by immunohistochemistry. p75 neurotrophin receptor mRNA was examined by quantitative real-time polymerase chain reactions. At 24 hours after modeling, cellular apoptosis occured around hematoma with upregulation of p75 neurotrophin receptor protein and mRNA was observed, which directly correlated to apoptosis. This observation indicated that p75 neurotrophin receptor upregulation was associated with cell apoptosis around hematomas after intracerebral hemorrhage.
文摘Neurodegenerative diseases and neural injury are 2 of the most feared disorders that afflict humankind by leading to permanent paralysis and loss of sensation.Cell based treatment for these diseases had gained special interest in recent years.Previous studies showed that dental pulp stem cells(DPSCs) could differentiate toward functionally active neurons both in vitro and in vivo,and could promote neuranagenesis through both cell-autonomous and paracrine neuroregenerative activities.Some of these neuroregenerative activities were unique to tooth-derived stem cells and superior to bone marrow stromal cells.However,DPSCs used in most of these studies were mixed and unfractionated dental pulp cells that contain several types of cells,and most were fibroblast cells while just contain a small portion of DPSCs.Thus,there might be weaker ability of neuranagenesis and more side effects from the fibroblast cells that cannot differentiate into neural cells.p75 neurotrophin receptor(p75 NTR) positive DPSCs subpopulation was derived from migrating cranial neural crest cells and had been isolated from DPSCs,which had capacity of differentiation into neurons and repairing neural system.In this article,we hypothesize that p75 NTR positive DPSCs simultaneously have greater propensity for neuronal differentiation and fewer side effects from fibroblast,and in vivo transptantation of autologous p75 NTR positive DPSCs is a novel method for neuranagenesis.This will bring great hope to patients with neurodegenerative disease and neural injury.Supported by Key Basic Research Fund of Science and Technology Commission of Shanghai Municipality(10JC1408700).
文摘Background By unbiased stereological methods, we have observed preferential dorsal root ganglion （DRG） B-cell loss in rodents after nerve injury, and caspase-3 activation and cell loss were related to the present of p75 receptor （p75^NTR）. We hypothesized that DRG B-cells express higher levels of pro-apoptotic proteins as compared to A-cells and the expressions of pro-apoptotic proteins can be reduced by depletion of p75^NTR. This study aimed to identify the p75NTR involved apoptotic pathway in DRG neurons after nerve injury. Methods The p75NTR knockout mice （p75-/-） and wildtype Balb/C mice （p75＋/＋） were used in this study. The expressions of pro-apoptotic proteins, c-Jun-N-terminal kinase （JNK）, c-jun and p38 in DRG were evaluated with immunohistochemistry 2 and 7 days following unilateral sciatic nerve transection. In addition, extra-cellular related kinase （ERK）, a transducer of survival signals, was also tested with immunohistochemistry and Western blotting methods in these animal models. Results Phosphorylated JNK （P-JNK） and phosphorylated p38 （P-p38） were mainly located in small B-cells, whereas phosphorylated c-jun （P-c-jun） was located in both A- and B-cells. Phosphorylated ERK （P-ERK） was located in both B-cells and satellite cells. Axotomy dramatically increased the expressions of P-JNK and P-c-jun （paired t-test）, with no influence on the expressions of P-p38 and P-ERK. Furthermore, the increase of P-JNK in p75＋/＋ mice 2 days after nerve axotomy was approximately 2.2-folds of that in p75-/- mice （P=-0.001, unpaired t-test）. Conclusion p75NTR-dependent JNK-caspase-3 pathway is involved in DRG B-cell loss after nerve injury and JNK is not the unique upstream of c-jun activation.
基金a Ph D fellowship by FCT-Fundacao para a Ciência Tecnologia (SFRH/BD/135868/2018)(to SSC)。
文摘Axonal growth inhibitors are released during traumatic injuries to the adult mammalian central nervous system, including after spinal cord injury. These molecules accumulate at the injury site and form a highly inhibitory environment for axonal regeneration. Among these inhibitory molecules, myelinassociated inhibitors, including neurite outgrowth inhibitor A, oligodendrocyte myelin glycoprotein, myelin-associated glycoprotein, chondroitin sulfate proteoglycans and repulsive guidance molecule A are of particular importance. Due to their inhibitory nature, they represent exciting molecular targets to study axonal inhibition and regeneration after central injuries. These molecules are mainly produced by neurons, oligodendrocytes, and astrocytes within the scar and in its immediate vicinity. They exert their effects by binding to specific receptors, localized in the membranes of neurons. Receptors for these inhibitory cues include Nogo receptor 1, leucine-rich repeat, and Ig domain containing 1 and p75 neurotrophin receptor/tumor necrosis factor receptor superfamily member 19(that form a receptor complex that binds all myelin-associated inhibitors), and also paired immunoglobulin-like receptor B. Chondroitin sulfate proteoglycans and repulsive guidance molecule A bind to Nogo receptor 1, Nogo receptor 3, receptor protein tyrosine phosphatase σ and leucocyte common antigen related phosphatase, and neogenin, respectively. Once activated, these receptors initiate downstream signaling pathways, the most common amongst them being the Rho A/ROCK signaling pathway. These signaling cascades result in actin depolymerization, neurite outgrowth inhibition, and failure to regenerate after spinal cord injury. Currently, there are no approved pharmacological treatments to overcome spinal cord injuries other than physical rehabilitation and management of the array of symptoms brought on by spinal cord injuries. However, several novel therapies aiming to modulate these inhibitory proteins and/or their receptors are under investigation in ongoing clinical trials. Investigation has also been demonstrating that combinatorial therapies of growth inhibitors with other therapies, such as growth factors or stem-cell therapies, produce stronger results and their potential application in the clinics opens new venues in spinal cord injury treatment.
文摘Peripheral neuropathy is a condition where damage resulting from mechanical or pathological mechanisms is inflicted on nerves within the peripheral nervous system （PNS）. Physical injury is the most common cause and may result in nerves being partially or completely severed, crushed, compressed or stretched. Other causes include metabolic or endocrine disorders, with e.g.,
基金the National High Technology Program of China (863 Programs), No. 2006AA02A117
文摘We investigated nerve growth factor precursor （proNGF） and mature NGF expression in ischemic and non-ischemic cortices after cerebral ischemia-reperfusion injury. In both ischemic and non-ischemic cortices, proNGF was found to be present in the extracellular space and cytoplasm. In addition, mature NGF was expressed in extracellular space, but with a very low signal. In ischemic cortex only, proNGF was significantly decreased, reaching a minimal level at 1 day. Mature NGF was increased at 4 hours, then reached a minimal level at 3 days. The p75 neurotrophin receptor （p75NTR） was significantly decreased after ischemia, and increased at 3 days after ischemia. These results confirmed that proNGF was the predominant form of NGF during the pathological process of cerebral ischemia-repeffusion injury. In addition, our findings suggest that ischemic injury may influence the conversion of proNGF to mature NGF, and that proNGF/p75NTR may be involved in reperfusion injury.
文摘The carotid body (CB) is a small neural crest-derived organ that registers oxygen and glucose levels in blood and regulates ventilation. The most abundant cell type in the CB glomeruli is glomus or type I cells, which is enveloped by processes of sustentacular or type II cells. Growth and neurotrophic factors have been established as signaling molecules played an important role in the development of the CB. To gain insight whether these signaling molecules are present in the adult rat CB, we examined the expression and cellular localization of some neurotrophic factors and their corresponding receptors in this organ by immunohistochemistry. The results showed the presence of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF) as well as p75NTR, tyrosine kinase A receptor (TrkA), tyrosine kinase B receptor (TrkB) and GDNF family receptor alpha1 (GFRα1) in the adult CB. At the light-microscopical level, the immunoreactivity for NGF and both its low-affinity (p75) and high-affinity (TrkA) receptors was detected in the majority of glomus cells and also in a subset of sustentacular cells. BDNF and its receptors, p75 and TrkB, were observed in the glomus cells, too. Remarkably, the immunohistochemical analysis revealed that the neuron-like glomus cells, but not the glial-like sustentacular cells, expressed GDNF and GFRα1. Taken together with prior results, it can be inferred that neurotrophins may be involved in the CB cell differentiation and survival in adulthood, and may exert a potent glomic protective action as well. It is also presumable that GDNF production by glomus cells plays a pivotal role in permitting long-term viability of CB grafts, which permits their potential applicability in cell therapy as a promising tool in neurodegenerative disorders.
文摘In psychopharmacology of depression, we observe two ways of research. One group is focused on catecholamines action. Second one fixes attention on neuronal morphogenesis and synaptic plasticity. The intimate connection of astrocytes, neurons and synaptic endings determines glial participation in neural homeostasis. Consequently this situation enlarges the role of astrocytes in the CNS synaptic plasticity. Brain Derived Neurotrophic factor and its receptor TrkB suppose to coordinate both of the above mentioning signaling pathways in depression disturbances. In our experiment, we have exploited striatal tissue because in our opinion this structure is misjudged in pathophysiology of depression alas;Several hypothesis proposed striatum as important in future intention activity structure. RT-PCR analysis was used to determine D1, BDNF and TrkB mRNA expression in cultured striatal astroglial cells. Administration of three representative antidepressants (ADs) like amitriptyline, moclobemide and sertraline to astroglial culture medium increase the D1, BDNF/TrkB mRNA expression. Our previous study showed that the stimulation of cAMP to CREB pathway after D1 receptors excitation constituted a common response to ADs. The present results signify that D1, BDNF/TrkB link which is next neural track (after cAMP/PKA) involved in the CNS adaptation to external conditions altered by chronic ADs treatment. Moreover, the striatum tissue appears to be important formation which takes an active part in antidepressant action thus essential in depression disorder etiology.
基金National Institute of Neurological Disorders and Stroke,Grant/Award Number:2RF1NS095799National Natural Science Foundation of China,Grant/Award Number:31970044 and 91854115Beijing University of Technology Faculty of Environment and Life Seed Funding,Grant/Award Number:049000513202。
文摘β-Amyloid(Aβ)is a specific pathological hallmark of Alzheimer's disease(AD).Because of its neurotoxicity,AD patients exhibit multiple brain dysfunctions.Disease-modifying therapy(DMT)is the central concept in the development of AD thera-peutics today,and most DMT drugs that are currently in clinical trials are anti-Aβdrugs,such as aducanumab and lecanemab.Therefore,understanding Aβ's neurotoxic mechanism is crucial for Aβ-targeted drug development.Despite its total length of only a few dozen amino acids,Aβis incredibly diverse.In addition to the well-known Aβ_(1-42),N-terminally truncated,glutaminyl cyclase(QC)catalyzed,and pyroglutamate-modified Aβ(pEAβ)is also highly amyloidogenic and far more cytotoxic.The extracel-lular monomeric Aβ_(x-42)(x=1-11)initiates the aggregation to form fibrils and plaques and causes many abnormal cellular responses through cell membrane receptors and receptor-coupled signal pathways.These signal cascades further influence many cel-lular metabolism-related processes,such as gene expression,cell cycle,and cell fate,and ultimately cause severe neural cell damage.However,endogenous cellular anti-Aβdefense processes always accompany the Aβ-induced microenvironment alterations.Aβ-cleaving endopeptidases,Aβ-degrading ubiquitin-proteasome system(UPS),and Aβ-engulfing glial cell immune responses are all essential self-defense mechanisms that we can leverage to develop new drugs.This review discusses some of the most recent advances in understanding Aβ-centric AD mechanisms and suggests prospects for promising anti-Aβstrategies.
