Glial cell line-derived neurotrophic factor and brain-derived neurotrophic factor regulate the interaction between astrocytes and Schwann cells at the trigeminal root entry zone

The trigeminal root entry zone is the zone at which the myelination switches from peripheral Schwann cells to central oligodendrocytes.Its special anatomical and physiological structure renders it susceptible to nerve injury.The etiology of most primary trigeminal neuralgia is closely related to microvascular compression of the trigeminal root entry zone.This study aimed to develop an efficient in vitro model mimicking the glial environment of trigeminal root entry zone as a tool to investigate the effects of glial cell line-derived neurotrophic factor and brain-derived neurotrophic factor on the structural and functional integrity of trigeminal root entry zone and modulation of cellular interactions.Primary astrocytes and Schwann cells isolated from trigeminal root entry zone of postnatal rats were inoculated into a two-well silicon culture insert to mimic the trigeminal root entry zone microenvironment and treated with glial cell line-derived neurotrophic factor and brain-derived neurotrophic factor.In monoculture,glial cell line-derived neurotrophic factor promoted the migration of Schwann cells,but it did not have effects on the migration of astrocytes.In the co-culture system,glial cell line-derived neurotrophic factor promoted the bidirectional migration of astrocytes and Schwann cells.Brain-derived neurotrophic factor markedly promoted the activation and migration of astrocytes.However,in the co-culture system,brain-derived neurotrophic factor inhibited the migration of astrocytes and Schwann cells to a certain degree.These findings suggest that glial cell line-derived neurotrophic factor and brain-derived neurotrophic factor are involved in the regulation of the astrocyte-Schwann cell interaction in the co-culture system derived from the trigeminal root entry zone.This system can be used as a cell model to study the mechanism of glial dysregulation associated with trigeminal nerve injury and possible therapeutic interventions.

Effects of P2Y_1 receptor on glial fibrillary acidic protein and glial cell line-derived neurotrophic factor production of astrocytes under ischemic condition and the related signaling pathways

Objective The present study aimed to explore the role of P2Y1 receptor in glial fibrillary acidic protein （GFAP） production and glial cell line-derived neurotrophic factor （GDNF） secretion of astrocytes under ischemic insult and the related signaling pathways. Methods Using transient right middle cerebral artery occlusion （tMCAO） and oxygen-glucose-serum deprivation for 2 h as the model of ischemic injury in vivo and in vitro, immunofluorescence, quantitative real-time reverse transcription-polymerase chain reaction （RT-PCR）, Western blotting, enzyme linked immunosorbent assay （ELISA） were used to investigate location of P2Y1 receptor and GDNF, the expression of GFAP and GDNF, and the changes of signaling molecules. Results Blockage of P2Y1 receptor with the selective antagonist N^6-methyl-2′-deoxyadenosine 3′,5′-bisphosphate diammonium （MRS2179） reduced GFAP production and increased GDNF production in the antagonist group as compared with simple ischemic group both in vivo and in vitro. Oxygen-glucose-serum deprivation and blockage of P2Y1 receptor caused elevation of phosphorylated Akt and cAMP response element binding protein （CREB）, and reduction of phosphorylated Janus kinase2 （JAK2） and signal transducer and activator of transcription3 （STAT3, Ser727）. After blockage of P2Y1 receptor and deprivation of oxygen-glucose-serum, AG490 （inhibitor of JAK2） reduced phosphorylation of STAT3 （Ser727） as well as expression of GFAP; LY294002, an inhibitor of phosphatidylinositol 3-kinase （PI3-K）, decreased phosphorylation of Akt and CREB; the inhibitor of mitogen-activated protein kinase kinase 1/2 （MEK 1/2） U0126, an important molecule of Ras/extracellular signal- regulated kinase （ERK） signaling pathway, decreased the phosphorylation of JAK2, STAT3 （Ser727）, Akt and CREB. Conclusion These results suggest that P2Y1 receptor plays a role in the production of GFAP and GDNF in astrocytes under transient ischemic condition and the related signaling pathways may be JAK2/STAT3 and PI3-K/Akt/CREB, respectively, and that crosstalk probably exists between them.

Transfection of the glial cell line-derived neurotrophic factor gene promotes neuronal differentiation

Glial cell line-derived neurotrophic factor recombinant adenovirus vector-transfected bone marrow mesenchymal stem cells were induced to differentiate into neuron-like cells using inductive medium containing retinoic acid and epidermal growth factor. Cell viability, micro- tubule-associated protein 2-positive cell ratio, and the expression levels of glial cell line-derived neurotrophic factor, nerve growth factor and growth-associated protein-43 protein in the su- pernatant were significantly higher in glial cell line-derived neurotrophic factor/bone marrow mesenchymal stem cells compared with empty virus plasmid-transfected bone marrow mes- enchymal stem cells. Furthermore, microtubule-associated protein 2, glial cell line-derived neurotrophic factor, nerve growth factor and growth-associated protein743 mRNA levels in cell pellets were statistically higher in glial cell line-derived neurotrophic factor/bone marrow mesen- chymal stem cells compared with empty virus plasmid-transfected bone marrow mesenchymal stem cells. These results suggest that glial cell line-derived neurotrophic factor/bone marrow mesenchymal stem cells have a higher rate of induction into neuron-like cells, and this enhanced differentiation into neuron-like cells may be associated with up-regulated expression of glial cell line-derived neurotrophic factor, nerve growth factor and growth-associated protein-43.

Intraspinal transplantation of motoneuron-like cell combined with delivery of polymer-based glial cell line-derived neurotrophic factor for repair of spinal cord contusion injury

To evaluate the effects of glial cell line-derived neurotrophic factor transplantation combined with adipose-derived stem cells-transdifferentiated motoneuron delivery on spinal cord con-tusion injury, we developed rat models of spinal cord contusion injury, 7 days later, injected adipose-derived stem cells-transdifferentiated motoneurons into the epicenter, rostral and caudal regions of the impact site and simultaneously transplanted glial cell line-derived neuro-trophic factor-gelfoam complex into the myelin sheath. Motoneuron-like cell transplantation combined with glial cell line-derived neurotrophic factor delivery reduced cavity formations and increased cell density in the transplantation site. The combined therapy exhibited superior promoting effects on recovery of motor function to transplantation of glial cell line-derived neurotrophic factor, adipose-derived stem cells or motoneurons alone. These ifndings suggest that motoneuron-like cell transplantation combined with glial cell line-derived neurotrophic factor delivery holds a great promise for repair of spinal cord injury.

Intrastriatal glial cell line-derived neurotrophic factors for protecting dopaminergic neurons in the substantia nigra of mice with Parkinson disease

BACKGROUND： Substantia nigra is deep in position and limited in range, the glial cell line-derived neurotrophic factor （GDNF） injection directly into substantia nigra has relatively greater damages with higher difficulty. GDNF injection into striatum, the target area of dopaminergic neuron, may protect the dopaminergic neurons in the compact part of substantia nigra through retrograde transport. OBJECTIVE： To investigate the protective effect of intrastriatal GDNF on dopaminergic neurons in the substantia nigra of mice with Parkinson disease （PD）, and analyze the action pathway. DESIGN： A controlled observation. SETTING： Neurobiological Laboratory of Xuzhou Medical College. MATERIALS： Twenty-four male Kunming mice of 7 - 8 weeks old were used. GDNF, 1-methy1-4-pheny1-1,2,3,6-tetrahydropyridine （MPTP） were purchased from Sigma Company （USA）; LEICAQWin image processing and analytical system. METHODS： The experiments were carded out in the Neurobiological Laboratory of Xuzhou Medical College from September 2005 to October 2006. The PD models were established in adult KunMing mice by intraperitoneal injection of MPTP. The model mice were were randomly divided into four groups with 6 mice in each group： GDNF 4-day group, phosphate buffer solution （PSB） 4-day group, GDNF 6-day group and PSB 6-day group. Mice in the GDNF 4 and 6-day groups were administrated with 1 μ L GDNF solution （20 μ g/L, dispensed with 0.01 mol/L PBS） injected into right striatum at 4 and 6 days after model establishment. Mice in the PSB 4 and 6-day groups were administrated with 0.01 mol/L PBS of the same volume to the same injection at corresponding time points. ② On the 12^th day after model establishment, the midbrain tissue section of each mice was divided into 3 areas from rostral to caudal sides. The positive neurons of tyroxine hydroxylase （TH） and calcium binding protein （CB） with obvious nucleolus and clear outline were randomly selected for the measurement, and the number of positive neurons in unit area was counted. MAIN OUTCOME MEASURES： Number of positive neurons of TH and CB in midbrain substantia nigra of mice in each group. RESULTS： All the 24 mice were involved in the analysis of results. The numbers of TH^＋ and CB^＋ neurons in the GDNF 4-day group （54.33±6.92, 46.33±5.54） were obviously more than those in the PBS 4-day group （27.67±5.01, 21.50±5.96, P 〈 0.01）. The numbers of TH^＋ and CB^＋ neurons in the GDNF 6-day group （75.67±5.39, 69.67±8.69） were obviously more than those in the PBS 6-day group （27.17±4.50, 21.33 ±5.72, P 〈 0.01） and those in the GDNF 4-day group （P 〈 0.01 ）. CONCLUSION： Intrastriatal GDNF can protect dopaminergic neurons in substantia nigra of PD mice, and it may be related to the increase of CB expression.

Electroacupuncture promotes peripheral nerve regeneration after facial nerve crush injury and upregulates the expression of glial cell-derived neurotrophic factor

The efficacy of electroacupuncture in the treatment of peripheral facial paralysis is known, but the specific mechanism has not been clarified. Glial cell-derived neurotrophic factor(GDNF) has been shown to protect neurons by binding to N-cadherin. Our previous results have shown that electroacupuncture could increase the expression of N-cadherin mRNA in facial neurons and promote facial nerve regeneration. In this study, the potential mechanisms by which electroacupuncture promotes nerve regeneration were elucidated through assessing the effects of electroacupuncture on GDNF and N-cadherin expression in facial motoneurons of rabbits with peripheral facial nerve crush injury. New Zealand rabbits were randomly divided into a normal group(normal control, n = 21), injury group(n = 45) and electroacupuncture group(n = 45). Model rabbits underwent facial nerve crush injury only. Rabbits in the electroacupuncture group received facial nerve injury, and then underwent electroacupuncture at Yifeng(TE17), Jiache(ST6), Sibai(ST2), Dicang(ST4), Yangbai(GB14), Quanliao(SI18), and Hegu(LI4; only acupuncture, no electrical stimulation). The results showed that in behavioral assessments, the total scores of blink reflex, vibrissae movement, and position of apex nasi, were markedly lower in the EA group than those in the injury group. Hematoxylin-eosin staining of the right buccinator muscle of each group showed that the cross-sectional area of buccinator was larger in the electroacupuncture group than in the injury group on days 1, 14 and 21 post-surgery. Toluidine blue staining of the right facial nerve tissue of each group revealed that on day 14 post-surgery, there was less axonal demyelination and fewer inflammatory cells in the electroacupuncture group compared with the injury group. Quantitative real time-polymerase chain reaction showed that compared with the injury group, N-cadherin mRNA levels on days 4, 7, 14 and 21 and GDNF mRNA levels on days 4, 7 and 14 were significantly higher in the electroacupuncture group. Western blot assay displayed that compared with the injury group, the expression of GDNF protein levels on days 7, 14 and 21 were significantly upregulated in the electroacupuncture group. The histology with hematoxylin-eosin staining and Nissl staining of brainstem tissues containing facial neurons in the middle and lower part of the pons exhibited that on day 7 post-surgery, there were significantly fewer apoptotic neurons in the electroacupuncture group than in the injury group. By day 21, there was no significantly difference in the number of neurons between the electroacupuncture and normal groups. Taken together, these results have confirmed that electroacupuncture promotes regeneration of peripheral facial nerve injury in rabbits, inhibits neuronal apoptosis, and reduces peripheral inflammatory response, resulting in the recovery of facial muscle function. This is achieved by up-regulating the expression of GDNF and N-cadherin in central facial neurons.

Establishment and expression of recombinant human glial cell linederived neurotrophic factor and TNF α receptor in human neural stem cells

Objective:To investigate the interference and expression of human glial cell line-derived neurotrophic factor(hCDNF) and soluble TNF alpha(sTMFRⅠ) receptor genes in neural stem cells and to evaluate the roles of these proteins in the genetic treatment of spinal cord injury.Methods:Full-length of GDNF cDNA(538 bp) and sTMFRⅠcDNA(504 bp) were inserted into the early 1 region of adenovirus genomic DNA respectively and were immediated by the human cytomegalovirus(gene promoter/enhancer). These adenoviruses were propagated in HEK293 cells via homologous recombination for 7-10 days in vivo,then they were used to infect human neural stem ceils.The infection and expression of gene were tested under immunofluorescence.ELISA and Westem-blot after 48 hours.Results:Almost all the cultured cells showed the nestin immunofluorescence positive staining,which was the characteristics of neural stem cell.A great quantity of EGFP and KFP were observed in neural stem cells,which indicated the expression of GDNF and sTMFRⅠ.After transfection of GDNF and sTMFRⅠgenes,many neural stem cells show GFAP and tubulin immunofluorescence positive staining,which meant that most neural stem cells differentiated into neuron at that condition.Conclusions:The infective efficiency of adenovirus is greatly acceptable to neural stem cell,thus adenovirus provide a useful vector for exogenous GDNF and sTMFRⅠgenes expressing in neural stem cells,which is useful for differentiation of neural stem cell.

Therapeutic potential of glial cell line-derived neurotrophic factor and cell reprogramming for hippocampal-related neurological disorders

Hippocampus serves as a pivotal role in cognitive and emotional processes,as well as in the regulation of the hypothalamus-pituitary axis.It is known to undergo mild neurodegenerative changes during normal aging and severe atrophy in Alzheimer's disease.Furthermore,dysregulation in the hippocampal function leads to epilepsy and mood disorders.In the first section,we summarized the most salient knowledge on the role of glial cell-line-derived neurotrophic factor and its receptors focused on aging,cognition and neurodegenerative and hippocampal-related neurological diseases mentioned above.In the second section,we reviewed the therapeutic approaches,particularly gene therapy,using glial cell-line-derived neurotrophic factor or its gene,as a key molecule in the development of neurological disorders.In the third section,we pointed at the potential of regenerative medicine,as an emerging and less explored strategy for the treatment of hippocampal disorders.We briefly reviewed the use of partial reprogramming to restore brain functions,non-neuronal cell reprogramming to generate neural stem cells,and neural progenitor cells as source-specific neuronal types to be implanted in animal models of specific neurodegenerative disorders.

Secretion of nerve growth factor,brain-derived neurotrophic factor,and glial cell-line derived neurotrophic factor in co-culture of four cell types in cerebrospinal fluid-containing medium

The present study co-cultured human embryonic olfactory ensheathJng cells, human Schwann cells, human amniotic epithelial cells and human vascular endothelial cells in complete culture medium- containing cerebrospinal fluid. Enzyme linked immunosorbent assay was used to detect nerve growth factor, brain-derived neurotrophic factor, and glial cell line-derived neurotrophic factor secretion in the supernatant of co-cultured cells. Results showed that the number of all cell types reached a peak at 7-10 days, and the expression of nerve growth factor, brain-derived neurotrophic factor, and glial cell line-derived neurotrophic factor peaked at 9 days. Levels of secreted nerve growth factor were four-fold higher than brain-derived neurotrophic factor, which was three-fold higher than glial cell line-derived neurotrophic factor. Increasing concentrations of cerebrospinal fluid （10%, 20% and 30%） in the growth medium caused a decrease of neurotrophic factor secretion Results indicated co-culture of human embryonic olfactory ensheathing cells, human Schwann cells human amniotic epithelial cells and human vascular endothelial cells improved the expression of nerve growth factor, brain-derived neurotrophic factor, and glial cell line-derived neurotrophic factor. The reduction of cerebrospinal fluid extravasation at the transplant site after spinal cord injury is beneficial for the survival and secretion of neurotrophic factors from transplanted cells.

Glial cell line-derived neurotrophic factor as a treatment after spinal cord injury

Spinal cord injury（SCI）is a devastating trauma that currently affects 54 people out of every million,which is approximately 270,000people in the United States（National Spinal Cord Injury Statistical Center,2013）.The effects of such an injury can cause a loss of both motor and sensory function below the injury site,normally leaving the patient unable to care for themselves entirely and relying on family and friends to provide personal care.Currently there are no.

Differential expression of glial cell line-derived neurotrophic factor splice variants in the mouse brain

Glial cell line-derived neurotrophic factor(GDNF) plays a critical role in neuronal survival and function. GDNF has two major splice variants in the brain,α-pro-GDNF and β-pro-GDNF, and both isoforms have strong neuroprotective effects on dopamine neurons. However, the expression of the GDNF splice variants in dopaminergic neurons in the brain remains unclear. Therefore, in this study, we investigated the mRNA and protein expression of α-and β-pro-GDNF in the mouse brain by real-time quantitative polymerase chain reaction, using splice variant-specific primers, and western blot analysis. At the mRNA level,β-pro-GDNF expression was significantly greater than that of α-pro-GDNF in the mouse brain. In contrast, at the protein level,α-pro-GDNF expression was markedly greater than that of β-pro-GDNF. To clarify the mechanism underlying this inverse relationship in mRNA and protein expression levels of the GDNF splice variants, we analyzed the expression of sorting protein-related receptor with A-type repeats(SorLA) by real-time quantitative polymerase chain reaction. At the mRNA level, SorLA was positively associated with β-pro-GDNF expression, but not with α-pro-GDNF expression. This suggests that the differential expression of α-and β-pro-GDNF in the mouse brain is related to SorLA expression. As a sorting protein, SorLA could contribute to the inverse relationship among the mRNA and protein levels of the GDNF isoforms. This study was approved by the Animal Ethics Committee of Xuzhou Medical University, China on July 14, 2016.

Use of RNAi silencing to target preconditioned glial cell line-derived neurotrophic factor in neuronal apoptosis

Several studies have suggested that exogenous glial cell line-derived neurotrophic factor may pro-tect neurons from cerebral ischemic injury. However, the mechanisms underlying the neuroprotec-tive effects of endogenous glial cell line-derived neurotrophic factor remain unclear. The present experiments sought to elucidate the influence of various conditioned media on neuronal apoptosis, using a normal culture medium for astrocytes, an astrocyte medium highly expressing glial cell line-derived neurotrophic factor, and an astrocyte medium in which glial cell line-derived neurotro-phic factor expression was silenced using RNAi technology. The results confirmed that the use of RNAi silencing to target pretreated glial cell line-derived neurotrophic factor expression promoted neuronal apoptosis. In addition, oxygen and glucose deprivation preconditioning was found to upregulate glial cell line-derived neurotrophic factor expression, and significantly reduce neuronal apoptosis.

Stem cell transplantation and/or adenoviral glial cell line-derived neurotrophic factor promote functional recovery in hemiparkinsonian rats

BACKGROUND Parkinson’s disease(PD)is a neurological disorder characterized by the progressive loss of midbrain dopamine(DA)neurons.Bone marrow mesenchymal stem cells(BMSCs)can differentiate into multiple cell types including neurons and glia.Transplantation of BMSCs is regarded as a potential approach for promoting neural regeneration.Glial cell line-derived neurotrophic factor(GDNF)can induce BMSC differentiation into neuron-like cells.This work evaluated the efficacy of nigral grafts of human BMSCs(hMSCs)and/or adenoviral(Ad)GDNF gene transfer in 6-hydroxydopamine(6-OHDA)-lesioned hemiparkinsonian rats.AIM To evaluate the efficacy of nigral grafts of hMSCs and/or Ad-GDNF gene transfer in 6-OHDA-lesioned hemiparkinsonian rats.METHODS We used immortalized hMSCs,which retain their potential for neuronal differentiation.hMSCs,preinduced hMSCs,or Ad-GDNF effectively enhanced neuronal connections in cultured neurons.In vivo,preinduced hMSCs and/or Ad-GDNF were injected into the substantia nigra(SN)after induction of a unilateral 6-OHDA lesion in the nigrostriatal pathway.RESULTS Hemiparkinsonian rats that received preinduced hMSC graft and/or Ad-GDNF showed significant recovery of apomorphine-induced rotational behavior and the number of nigral DA neurons.However,DA levels in the striatum were not restored by these therapeutic treatments.Grafted hMSCs might reconstitute a niche to support tissue repair rather than contribute to the generation of new neurons in the injured SN.CONCLUSION The results suggest that preinduced hMSC grafts exert a regenerative effect and may have the potential to improve clinical outcome.

Impact of Pitx3 gene knockdown on glial cell line-derived neurotrophic factor transcriptional activity in dopaminergic neurons

Pitx3 is strongly associated with the phenotype, differentiation, and survival of dopaminergic neurons. The relationship between Pitx3 and glial cell line-derived neurotrophic factor（GDNF） in dopaminergic neurons remains poorly understood. The present investigation sought to construct and screen a lentivirus expression plasmid carrying a rat Pitx3 short hairpin（sh）RNA and to assess the impact of Pitx3 gene knockdown on GDNF transcriptional activity in MES23.5 dopaminergic neurons. Three pairs of interference sequences were designed and separately ligated into GV102 expression vectors. These recombinant plasmids were transfected into MES23.5 cells and western blot assays were performed to detect Pitx3 protein expression. Finally, the most effective Pitx3 sh RNA and a dual-luciferase reporter gene plasmid carrying the GDNF promoter region（GDNF-luciferase） were cotransfected into MES23.5 cells. Sequencing showed that the synthesized sequences were identical to the three Pitx3 interference sequences. Inverted fluorescence microscopy revealed that the lentivirus expression plasmids carrying Pitx3-sh RNA had 40-50% transfection efficiency. Western blot assay confirmed that the corresponding Pitx3 of the third knockdown sequence had the lowest expression level. Dual-luciferase reporter gene results showed that the GDNF transcriptional activity in dopaminergic cells cotransfected with both plasmids was decreased compared with those transfected with GDNF-luciferase alone. Together, the results showed that the designed Pitx3-sh RNA interference sequence decreased Pitx3 protein expression, which decreased GDNF transcriptional activity.

Postnatal roles of glial cell line-derived neurotrophic factor family members in nociceptors plasticity

The neurotrophin and glial cell line-derived neurotrophic factor(GDNF) family of growth factors have been extensively studied because of their proven ability to regulate development of the peripheral nervous system.The neurotrophin family,which includes nerve growth factor(NGF),NT-3,NT4/5 and BDNF,is also known for its ability to regulate the function of adult sensory neurons.Until recently,little was known concerning the role of the GNDF-family(that includes GDNF,artemin,neurturin and persephin) in adult sensory neuron function.Here we describe recent data that indicates that the GDNF family can regulate sensory neuron function,that some of its members are elevated in inflammatory pain models and that application of these growth factors produces pain in vivo.Finally we discuss how these two families of growth factors may converge on a single membrane receptor,TRPV1,to produce long-lasting hyperalgesia.

A combination of chondroitinase ABC,glial cell line-derived neurotrophic factor,and Nogo A antibody delayed-release microspheres for the treatment of spinal cord injury

The purpose of this study was to evaluate the effect of poly（lactide-co-glycolic acid） delayed-release microspheres,which were prepared using glial cell line-derived neurotrophic factor（GDNF）,on the delayed-release,controllability,and protection of GDNF activity.The present study is the first to combine chondroitinase ABC,GDNF,and Nogo A antibody delayed-release microspheres for the treatment of spinal cord injury.Results show that the combined therapy of chondroitinase ABC,GDNF,and Nogo A antibody microspheres can increase the immunoreaction of neurofilament 200 in the injured spinal cord,and this therapeutic effect was better than chondroitinase ABC,GDNF,or Nogo A antibody microspheres administered singularly.

Effect of glial cell line-derived neurotrophic factor on peripheral nerve regeneration in adult rat

Objective:To studytheeffectof glialcellline-derivedneurotrophic(GDNF)on adultperipheralnerve regeneration.Methods:Transectionedsciaticnerveinadultratswassuturedintosiliconechannel.GDNFor SALsolution wasinjectedintothesiliconechannelsduringoperation.Fourweekslater,theeffectof GDNFon axonalregenerationwas evaluatedby degenerativeneurofiberstainingandHRPretrogradetracing.Results:ComparedwithSAL group,the percentageof degenerativeneurofiberareasdecreasedfrom17.3%to1.9%(P<0.01)andtheratioof labeledspinalsomas numberwassignificantlyincreasedfrom43.5%to68.3%(P<0.01)inGDNFgroup.Conclusion:Theresultssuggestthat exogenousGDNFcanobviouslyenhanceadultperipheralnerveregeneration.

Depletion of Glial Cell Line-Derived Neurotrophic Factor by Disuse Muscle Atrophy Exacerbates the Degeneration of Alpha Motor Neurons in Caudal Regions Remote from the Spinal Cord Injury

We have been previously reported that disuse muscle atrophy exacerbates both motor neuron (MN) degeneration in caudal regions remote from a spinal cord injury, and decrease in glial cell line-derived neurotrophic factor (GDNF) protein level in paralyzed muscle. In this study we found that disuse muscle atrophy exacerbated the decrease in GDNF protein level in the L4/5 spinal cord, which was not immunopositive for GDNF. Our results were consistent with the fact that in the lumbar spinal cord of rats with mid-thoracic contusion, GDNF expression was not detected, while expression of GDNF receptors (GFRα1 and RET) was. Our study showed that administration of exogenous recombinant GDNF into the atrophic muscle partially rescued α-MN degeneration in the L4/5 spinal cord. These results suggest that the depletion of GDNF protein by muscle atrophy exacerbates α-MN degeneration in caudal regions remote from the injury.

Effects of lateral ventricular transplantation of bone marrow-derived mesenchymal stem cells modified with brain-derived neurotrophic factor gene on cognition in a rat model of Alzheimer's disease

In the present study, transplantation of bone marrow-derived mesenchymal stem cells modified with brain-derived neurotrophic factor gene into the lateral ventricle of a rat model of Alzheimer＇s disease, resulted in significant attenuation of nerve cell damage in the hippocampal CA1 region. Furthermore, brain-derived neurotrophic factor and tyrosine kinase B mRNA and protein levels were significantly increased, and learning and memory were significantly improved. Results indicate that transplantation of bone marrow-derived mesenchymal stem cells modified with brain-derived neurotrophic factor gene can significantly improve cognitive function in a rat model of Alzheimer＇s disease, possibly by increasing the levels of brain-derived neurotrophic factor and tyrosine kinase B in the hippocampus.

Brain-derived neurotrophic factors increase the proliferation and differentiation of endogenous neural stem cells in mouse models of cerebral infarction

BACKGROUND： It has been confirmed that brain-derived neurotrophic factor （BDNF） can promote the proliferation of neural stem cells （NSCs） and protect neuron-like cells in vitro. However, its effect on endogenous NSCs in vivo is still unclear. OBJECTIVE： To evaluate whether BDNF can induce the endogenous NSCs to proliferate and differentiate into the neurons in the mice model of cerebral infarction. DESIGN： A synchronal controlled observation. SETTINGS： Department of Neurology, Microbiology Division of the Department of Laboratory, Tianjin First Central Hospital; Howard Florey Institute, Medical College, the University of Melbourne. MATERIALS： Twenty-four pure breed C57BL/6J mice at the age of 10 weeks old （12 males and 12 females） were divided into saline control group and BDNF-treated group, 6 males and 6 females in each group. METHODS： The experiments were performed at the University of Melbourne from July 2004 to February 2005. ① The left middle cerebral artery （MCA） was ligated in both groups to establish models of cerebral infarction and the Matsushita measuring method was used to monitor the blood flow of the lesioned region supplied by MCA. 75% reduction of blood flow should be reached in the lesioned region. ② At 24 hours after infarction, mice in the BDNF-treated group were administrated with BDNF, which was slowly delivered using an ALZET osmium pump design. BDNF was dissolved in saline at the dosage of 500 mg/kg and injected into the pump, which could release the solution consistently in the following 28 days. The mice in the saline control group accepted the same volume of saline at 24 hours after infarction. ③ The Rotarod function test began at 1 week preoperatively, the time stayed on Rotarod was recorded. The mice were tested once a day till the end of the experiment. At 4 weeks post cerebral infarction, double labeling of Nestin and GFAP, BIH tubulin and CNPase immunostaining was performed to observe the differentiation directions of the re-expressed endogenous NSCs, and the percentages of the cells differentiated into astrocytes, neurons and oligodendrocytes were calculated. MAIN OUTCOME MEASURES： ① The differentiation directions of the re-expressed endogenous NSCs, and the percentage of the cells differentiated into astrocytes, neurons and oligodendrocytes.② Comparison of motor function between the two groups. RESULTS： All the 24 pure C57BL/6J mice were involved in the analysis of results. ①Positively expressed endogenous NSCs appeared in the mice of both groups, and they mainly distributed around the focus of lesion, as well as the contralateral side. The expressed cells in the BDNF-treated group were obviously more than those in the saline control group. ②Activations of endogenous NSCs： At 4 weeks after infarction, re-expressions of endogenous NSCs appeared in both groups. The number of the re-expressed cells in the BDNF-treated group was about 4.2 times higher than that in the saline control group. The percentage of the cells differentiated into neurons in the BDNF-treated group was significantly higher than that in the saline control group （36%, 15%）, the percentage of the cells differentiated into astrocytes was lower than that in the saline control group （54%, 77%）, whereas the percentage of the cells differentiated into oligodendrocytes was similar to that in the saline control group （10%, 8%）. ③ Results of motor functional test： Compared with before cerebral infarction, the mice in both groups manifested as obvious decrease in motor function at 1 week after infarction, whereas the recovery of motor function in the BDNF-treated group was significantly superior to that in the saline control group at 2, 3 and 4 weeks （P 〈 0.01）. CONCLUSION： BDNF can promote the proliferation of endogenous NSCs in the brain of mice with cerebral infarction, it can decrease the differentiation rate of astrocytes, and increase the differentiation rate of neurons. BDNF has small influence on the differentiation of endogenous NSCs into oligodendrocytes, which was not benefit for the recovery of neural axon. Endogenous NSCs may improve the motor function of mice through the above pathways.