ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90047-7

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractBrain‐derived neurotrophic factor (BDNF), nerve growth factor (NGF) and neurotrophin‐3 (NT‐3) are structurally related survival and differentiation factors for distinct sets of peripheral and central neurons. We previously reported that BDNF and NGF gene expression are differentially regulated in mouse L929 fibroblasts. Here we examine expression of these three neurotrophins in human fibroblasts. Northern blots detected BDNF and NT‐3 mRNAs in fibroblasts derived from lung (WI‐38), calvarium and foreskin. WI‐38 cells and foreskin fibroblasts expressed 1.6 kb as well as 4 kb BDNF mRNAs whereas only the smaller BDNF mRNA was detected in calvarium fibroblasts. NGF mRNA was present in foreskin and calvarium but not lung fibroblasts. In WI‐38 cells serum treatment increased levels of BDNF mRNA within 2 hr. Cycloheximide did not inhibit the increase. Treatment with 12‐O‐tetradecanoyl phorbol‐13‐acetate (TPA) transiently suppressed BDNF mRNA. Treatment with both serum and TPA first stimulated and then transiently suppressed BDNF mRNA. TPA and/or serum did not significantly affect BDNF mRNA in calvarium fibroblasts. These results show that human fibroblasts derived from different tissues express and regulate neurotrophin genes differentially.

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90048-5

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractGestational malnutrition induces an acceleration of the serotonin biosynthetic pathway in the developing brain with an increase in brain L‐tryptophan (L‐Trp), tryptophan‐5‐hydroxylase (TrpOH) activity and serotonin content. In the present work we report results on the possible mechanism of TrpOH activation. Kinetic experiments were done with different L‐Trp concentrations in the rat brain at different ages. Also various phosphorylating conditions of the enzyme were tested in order to compare its activation in developmentally malnourished and normal brains. The results showed lowerKmvalues and no changes in theVmaxin the malnourished as compared to controls. Interestingly, in the malnourished group, TrpOH showed an increased activity under the phosphorylating conditions employed. We propose that in the activation of brain TrpOH by developmental malnutrition, not only is an elevation of L‐Trp involved, but also a change in the enzyme itself reflected in a higher affinity for L‐Trp and in a greater response to phosphorylation. This allows us to propose the possibility that early chronic malnutrition induces structural changes in the enzymatic molecule.

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90049-3

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractCell type‐specific and developmental patterns of APP expression were investigated in rat brain and cultured neural cells. Nearly all astrocytes were APP‐positive, whereas only selected population of neurons appeared to express APP. In these neurons, APP immunoreactivity was preferentially restricted to single processes. mRNAs encoding the major APP isoforms, APP695and APP770, were co‐expressed as 3.4–3.6 kb transcripts both in astrocytes and neurons. In addition, an unusual 2.8 kb mRNA size class was revealed in cultured cerebellar granule neurons by means of the probe recognizing APP770mRNA. Also, for the first time, APP714mRNA was detected in rat brain by northern blotting. The steady‐state levels of these transcripts were increased from birth up to postnatal day 20, whereas no apparent changes were observed after reaching adulthood. These data hint at the involvement of APP in the major morphogenetic events taking place in rat brain during the first three postnatal weeks.

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90050-7

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe role of the nerve growth factor family of neurotrophins in the development of cochlear and vestibular ganglia is unclear. In order to predict the potential importance of nerve growth factor, brain‐derived neurotrophic factor or neurotrophin‐3, we examined the expression of neurotrophin mRNA and full‐length neurotrophin receptor mRNA byin‐situhybridization and reverse transcription‐polymerase chain reaction, as well as whether high affinity125I‐nerve growth factor binding was present, in cochlear and vestibular ganglia of the quail at several stages of development (stages 26, 31 and 36). Nerve growth factor, brain‐derived neurotrophic factor and neurotrophin‐3 mRNA was detected at all ages examined, suggesting that these neurotrophins may serve an autocrine or paracrine function, especially prior to target contact. In addition, we found full‐lengthtrkA andtrkC mRNA was expressed, the products of which are the functional neuronal receptors for nerve growth factor and neurotrophin‐3, respectively. Although full‐lengthtrkA mRNA was found, physiologically important high affinity125I‐nerve growth factor binding was not detected. Since nerve growth factor's effects on survival and neurite outgrowth are mediated through high affinity binding, nerve growth factor may serve an as yet unidentified role in this system. Full‐lengthtrkB mRNA, the product of which is the functional neuronal receptor for brain‐derived neurotrophic factor, was not detected using reverse transcription‐polymerase chain reaction, however, truncated (non‐catalytic)trkB was present, at least in cochlear ganglia at stage 31. It is not known what function may be subserved by these truncated receptors.

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90051-5

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe spatial control of neuronal cell attachment and differentiation via specific receptor mediated interactions, may provide an effective means for thein vitroreconstruction of neuronal cell architecture. In this study, receptor‐specific oligopeptide sequences derived from the extracellular matrix (ECM) molecule laminin, a potent neural cell attachment and differentiation promoter were covalently bound on fluorinated ethylene propylene (FEP) films. The degree of receptor‐specific cell attachment and the ability to spatially control neurite outgrowth by covalently patterning the oligopeptide sequences on the FEP film surface were assessed.FEP films were first chemically activated with a Radio Frequency Glow Discharge (RFGD) process that covalently replaces the surface fluorine atoms with reactive hydroxyl groups. Oligopeptides containing the YIGSR sequence from the B1 chain of laminin and the water soluble oligopeptide containing the IKVAV sequence (CSRARKQAASIKVAVSADR) from the A chain were covalently bound to the hydroxylated FEP films. Electron Spectroscopy for Chemical Analysis (ESCA) verified the covalent attachment of the oligopeptides to the material surface.The degree of receptor mediated NG108‐15 cell attachment on immobilized CDPGYIGSR films was determined using competitive binding media. A 78% reduction in cell attachment was observed on films containing CDPGYIGSR in the cell plating medium. Only a 23% reduction in cell attachment was noted on films plated in medium containing a mock CDPGYIGSK sequence. FEP films immobilized with the IKVAV oligopeptide sequence were shown to mediate PC12 cell attachment and a competitive binding medium also significantly attenuated cell attachment on the immobilized films.The spatial patterning of these oligopeptide sequences to the FEP surface was shown to localize cell attachment and neurite extension on the patterned pathways. The surrounding unmodified FEP surface was inhibitory in serum containing medium and prevented cellular interactions outside the oligopeptide modifications. The spatial immobilization of laminin oligopeptides on FEP films provides a means to organize the attachment and differentiation of neuronal cells in a receptor‐specific manner.

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90052-3

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe purpose of the present study was to investigate whether or not cerebral glucose utilization is changed locally after damage of the neuronal insulin receptor by means of intracerebroventricular (icv) streptozotocin (STZ) administered in a subdiabetogenic dosage (1.5 mg/kg bw.). STZ was administered at the start of the study, and 2 and 21 days later bilaterally into the cerebral ventricles in rats of a mean age of 18 months. The local distribution of cerebral glucose utilization was analyzed in conscious rats on the 42nd day after the first STZ injection using the quantitative (14C)‐2‐deoxyglucose method. Of the 35 brain structures investigated from autoradiograms of brain sections, 17 showed a reduction in glucose utilization. Decreases in glucose utilization were observed in the frontal, parietal, sensory motor, auditory and entorhinal cortex and in all hippocampal subfields. In contrast, glucose utilization was increased in two white matter structures. The decrease in cerebral glucose utilization observed in cortical and hippocampal areas in the present study may correspond to changes in morphobiological parameters which have been found in patients with Alzheimer's disease. The present data are in accordance with the hypothesis that an impairment in the control of neuronal glucose metabolism at the insulin receptor site may exist in sporadic dementia of Alzheimer type (DAT), and can be studied by the icv STZ animal model.

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90053-1

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractHippocampal levels of mRNA encoding nerve growth factor (NGF) and brain‐derived neurotrophic factor (BDNF) are rapidly induced by enhanced neuronal activity following seizures and glutamate or muscarinic receptor activation. However, the levels of neurotrophin‐3 (NT‐3) mRNA acutely decrease after limbic seizures suggesting that a different mode of regulation may exist for these neurotrophins. Here we show that BDNF and neurotrophin‐4 (NT‐4), but not NT‐3 itself, up‐regulate NT‐3 mRNA in cultured hippocampal neurons. In the rat hippocampus, the muscarinic receptor agonist, pilocarpine increased BDNF mRNA levels rapidly and those of NT‐3 with a delay of several hours. Injection of BDNF into neonatal rats elevated NT‐3 mRNA in the hippocampus which demonstrates that BDNF is able to enhance NT‐3 expressionin vivo. The regulation of NT‐3 by BDNF and NT‐4 enlargens the neurotrophic spectrum of these neurotrophins to include neuron populations responsive primarily to NT‐3.

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90054-X

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractMurine spinal cord and dorsal root ganglion GABAergic neurons, derived from 12‐day‐old fetuses, were examined autoradiographically, biochemically and immunocytochemicallyin vitroto determine the timecourse of appearance and maturation of this phenotype and the extent and mode of its innervation of target neurons. Specific3H‐GABA uptake into spinal cord neurons was the first property to develop and was present at the earliest time studied, one dayin vitro. Immunocytochemical localization of glutamic acid decarboxylase (GAD) revealed positively stained neurons beginning at four days. At five daysin vitro, electron microscopic immunocytochemistry revealed GAD‐immunoreactive (GAD‐IMR) boutons investing neuronal perikarya as well as neuronal processes. By one weekin vitro, GAD‐IMR neurons constituted 27% of the total population and GAD‐IMR boutons could be seen contacting every cell with a neuronal morphology. The mode of investment of target neurons by GAD‐IMR boutons was not circumscribed to either soma or dendrites but usually involved the entire neuronal perimeter and did not change with time in culture. Three morphologically distinct types of GAD‐IMR neurons were evident: a small, bipolar type; a medium‐sized multipolar neuron which was the most common and a large, multipolar type, resembling a motoneuron. A small population (8%) of dorsal root ganglion neurons was found to contain GAD both biochemicaly and immunocytochemically but was never invested by GAD‐IMR boutons. GAD activityin vitroparalleledin vivolevels with maximal activity being reached at four weeksin vitroand 10 days postnatally in the intact mouse spinal cord. Murine spinal cord GABAergic neurons are a morphologically diverse and abundant neuronal population with extensive, precocious innervation of all other neuronal phenotypesin vitrosuggesting that GABA has a widespread influence over other developing neuronal systems in the murine spinal cord.

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90055-8

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractWe have disrupted the integrity of the rat olfactory neuroepithelium using intranasally applied TX‐100, a procedure known to reversibly eliminate the sensory neuron input from the neuroepithelium to the olfactory bulb [Margoliset al.(1974) Denervation in the primary olfactory pathway of mice: biochemical and morphological effects.Brain Res.81, 469–483]. One week after TX‐100 exposure, we observed a disruption of the pseudo‐stratified organization of the neuroepithelium which was accompanied by a 60% reduction in neuroepithelial width, compared to saline‐treated controls. Full recovery of the neuroepithelium was not observed until 16 weeks post‐lesion. During this post‐lesion period, we monitored the expression of the low affinity receptor for neurotrophins, p75NGFR, in the olfactory bulb of saline‐ and TX‐100‐treated animals, using the monoclonal antibody, MAb192. In saline‐treated animals, p75NGFR‐immunoreactivity (p75NGFR‐ir) was localized to individual glomeruli in the olfactory bulb, with little or undetectable p75NGFR‐ir in the olfactory nerve layer. We have previously reported that pre‐lesioned levels of p75NGFR‐ir in the glomerular layer were dramatically reduced while an induction of p75NGFR‐ir was observed in the olfactory nerve layer, one and two weeks after intranasal exposure to TX‐100 [Turner&Perez‐Polo (1992) Regulation of the low affinity receptor for nerve growth factor, p75NGFR, in the olfactory system of neonatal and adult rat.Int. J. Devl Neurosci.10, 343–359]. In this paper, we demonstrate that this previously reported reduction in glomerular p75NGFR‐ir took 16 weeks to fully recover and was, thus, coincident with the post‐lesion recovery of the neuroepithelium. In the olfactory nerve layer, the return of p75NGFR‐ir to pre‐lesioned levels took only four weeks. No changes in neuroepithelial width and integrity or alterations in p75NGFR‐ir in the olfactory bulb were observed in saline‐treated animals. Thus, the TX‐100‐induced removal of the peripheral input to the olfactory bulb resulted in a reversible change in expression of p75NGFR‐ir in the bulb. We believe that these changes are a reflection of the regenerative capacity of the olfactory system.

ISSN:0736-5748    

DOI:10.1016/0736-5748(94)90056-6

出版商:Wiley    

年代:2003

数据来源: WILEY