摘要:

AbstractNerve growth factor (NGF), which has been shown to act as a morphological and neurochemical differentiating factor in PC12 cells, also protects PC12 cells from the toxicity of serum withdrawal and ischemia. By using a previously established in vitro model of ischemia, which incorporates the combination of anoxia with glucose deprivation (Boniece and Wagner: J Neurosci 13:4220–4228, 1993), we have been able to study the signal transduction pathways upon which NGF‐induced survival is dependent. Here we demonstrate that inhibitors of the N‐kinase and NGF‐induced neuritogenesis, 6‐thioguanine and 2‐aminopurine, prevent the protective effects of NGF, while they have little, if any, effect on the protection conferred by epidermal growth factor (EGF) or dbcAMP. This suggests that only NGF acts by a mechanism that depends strongly on the N‐kinase. Furthermore, the methyltransferase inhibitor 5′‐deoxy‐5′‐methylthioadenosine (MTA), which also inhibits NGF‐induced neuritogenesis, inhibits the protective effect of NGF but not the protective effects of EGF or dbcAMP. Thus, the neuroprotective effect of NGF requires some of the same signal transduction steps used by NGF to promote differentiation and neurite formation. Furthermore, we found that exposure of PC12 cells to retinoic acid, which promotes the differentiation and inhibits the growth of PC12 cells, also improves cell survival during ischemia. In addition, a combination of NGF and retinoic acid was more effective than either agent alone. It is likely that these two agents confer protection by independent pathway

ISSN:0360-4012    

DOI:10.1002/jnr.490400102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractNeurotropic strains of mouse hepatitis virus (MHV) have been used extensively for the study of viral pathogenesis in the central nervous system (CNS), serving as models for human neurological diseases such as multiple sclerosis (MS). MHV strains A59 and JHMV both cause acute and chronic encephalomyelitis and demyelination in susceptible strains of mice and rats. In acute disease, CNS damage is most likely the result of lytic infection in neurons and oligodendrocytes, and death can be prevented by the adoptive transfer of Class I‐restricted CD8+ T cells. However, in later stages of the disease induced by some MHV strains, virus tends to be restricted to astrocytes in a nonlytic infection, and the immune response appears to contribute to CNS damage. These data lead us to suggest that the astrocyte may play a central role in the neuropathogenesis of MHV infection. Consistent with this possibility, A59 has been reported to induce the expression of Class I molecules of the major histocompatibility complex (MHC) in glial cells following infection in vivo and in vitro. In this communication, we have examined the influence of persistent infection by both A59 and JHMV on MHC Class I expression in primary murine astrocytes. Persistence was characterized by the presence of intracellular viral antigen and mRNA in the absence of detectable infectious virus particles. Under these conditions, JHMV, but not A59, inhibited constitutive expression of the H‐2 Kbmolecule, with the magnitude of inhibition increasing with postinfection time. A59 was not able to induce Class I during persistence, presumably due to the lack of infectious virus particles. Class I expression was restored by the addition of gamma‐interferon (IFN‐γ) to astrocytes persistently infected with either A59 or JHMV. Thus, Class I inhibition is not a permanent consequence of JHMV persistence, and persistence does not interfere with normal signalling pathways for Class I induction. © 1995 Wiley

ISSN:0360-4012    

DOI:10.1002/jnr.490400103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractAdrenal grafting for Parkinson's disease has led to modest functional improvement despite poor graft survival. One explanation is a neurotrophic response within the traumatized striatum. This study was undertaken to investigate the time course of the astrocytic response in vivo and in vitro, and the expression of ciliary neurotrophic factor (CNTF) mRNA following striatal injury. Unilateral stereotaxic biopsy of the rat striatum was performed and gelatin sponge (gelfoam) was immediately placed into the biopsy cavity. Rats were sacrificed on days 1,3,5,7,14, and 28 post biopsy. Immunohistochemical staining of the traumatized striatum with antibodies to glial fibrillary acidic protein (GFAP) was carried out. The reactive astrocytes which appeared within 7 days after trauma were mostly protoplasmic on the basis of morphology, and maximal on day 7, being 30 times the level in the normal striatum. After day 7, fibrous astrocytes appeared and increased up to day 28, while protoplasmic astrocytes decreased. In addition, immunocytochemical double staining of short term cultured astrocytes from the traumatized striatum with anti‐A2B5 and anti‐GFAP antibodies revealed that 84% and 90% of astrocytes were type 1 astrocytes on days 3 and 7, respectively; however, by day 28 47% of astrocytes were type 2. Northern blot analysis revealed that CNTF mRNA expression was up‐regulated and peaked on day 7, coincident with a predominance of protoplasmic astrocytes in vivo and type 1 astrocytes in vitro, respectively. These finding suggest that the expression of CNTF mRNA is part of the early astrocytic response to trauma, particularly associated with protoplasmic astrocytes in vivo and type 1 astrocytes in vitro. We conclude that reactive astrocytes are likely candidates to produce the neurite promoting activity seen in previous studies after trauma in the striatum. CNTF may represent an early signal in the astrocyte‐mediated neurotrophic and neurite promoting responses. © 1995 Wiley

ISSN:0360-4012    

DOI:10.1002/jnr.490400104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe aim of this study was to characterize the effects of cortical cholinergic denervation on cholinergic parameters in the cerebral cortex and basal forebrain using a novel immunotoxin (conjugate of the monoclonal antibody 192IgG against the low‐affinity nerve growth factor receptor armed with cytotoxin saporin) to efficiently and selectively lesion cholinergic neurons in rat basal forebrain. Seven days following an intracerebroventricular injection of the cholinergic immunotoxin 192IgG‐saporin the binding levels of nicotinic and M1‐ and M2‐muscarinic acetylcholine receptors (mAChR), high‐affinity choline uptake sites, as well as the m1‐m4 mAChR mRNA were determined in coronal brain sections by both receptor autoradiography and in situ hybridization, and quantified by image analysis. Hemicholinium‐3 binding to high‐affinity choline uptake sites was decreased by up to 45% in all cortical regions and in the hippocampus after a single injection of the immunotoxin compared to controls. In contrast, M1‐mAChR sites were increased over the corresponding control value in the anterior parts of cingulate, frontal, and piriform cortex by about 20%, in the hindlimb/forelimb areas (18%), in the parietal cortex (35%), in the occipital cortex area 2 (17%), as well as in the temporal cortex (25%) following immunolesion. M2‐mAChR levels were found to be significantly increased in the posterior part of the parietal cortex area 1 (by about 22%) and in the occipital cortex area 2 (20%) only. With respect to laminar cortical localization, M2‐mAChRs and choline uptake sites were altered in all cortical layers, whereas M1‐mAChRs were preferentially affected in the upper cortical layers by the immunolesion. The increase in M1‐mAChR binding in the temporal and occipital cortex as a consequence of the immunolesion was complemented by an increase in the amount of m1 and m3 mAChR mRNA of about 20% in these regions. The elevated levels of M2‐mAChR sites in the occipital and temporal cortex following immunolesion were accomplanied by an increase in the m4 (by 25%) but not m2 mAChR mRNA. There was no effect of the immunolesion on the m1‐m4 mAChR mRNA in frontal cortical regions. In the basal forebrain, however, immunolesioning caused about a 40% decrease in the level of m2 mAChR mRNA in the medial and lateral septum as well as in the vertical and horizontal limb of the diagonal band, whereas M1‐ and M2‐mAChR binding and the levels of m1, m3, and m4 mAChR mRNA were not affected by the immunolesion in any of the basal forebrain nuclei studied. Seven days after a single dose of the 192IgG‐saporin immunotoxin there was no change in the level of cortical nicotinic acetylcholine receptor sites in any of the regions studied compared to corresponding controls. The region‐specific changes in the level of M1‐ and M2‐mAChRs, as well as corresponding receptor gene expression and the lack of effects on cortical nicotinic receptors, may be part of an adaptive mechanism in response to cholinergic degeneration. These data further support the usefulness of the 192IgG‐saporin conjugate as an appropriate tool to produce cortical chol

ISSN:0360-4012    

DOI:10.1002/jnr.490400105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractA protein with a MWappof 50–70 kDa isolated from the salt extract of crude membranes from neonatal rat brain increases the numbers of oligodendroglia in mixed glial cultures prepared from neonatal rat cerebral white matter. After partial purification by ion exchange and gel exclusion chromatography, and elution from an SDS‐polyacrylamide gel, this protein ( “oligodendroglial trophic factor,” OTF) elicited half‐maximal oligodendroglial recruitment at a concentration of 5 ng/mL. OTF is a mitogen for oligodendroglia, and to a lesser extent, for oligodendroglial progenitor (O2A) cells, but does not stimulate proliferation of astroglia, Schwann cells, or endoneurial fibroblasts. OTF, unlike platelet‐derived growth factor (PDGF), is not an oligodendroglial survival factor. Antibodies against PDGF and basic fibroblast growth factor (bFGF) do not interfere with the accumulation of oligodendroglia induced by OTF. When OTF is given simultaneously with either PDGF or bFGF, there is an additive increase in the numbers of cells of the oligodendroglial lineage. © 1995 Wil

ISSN:0360-4012    

DOI:10.1002/jnr.490400106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractExpression of the putative pheromone and odorant transporter, vomeromodulin, was characterized in developing rat nasal mucosae using in situ hybridization and immunocytochemistry. Initial expression of vomeromodulin mRNA and protein was detected at embryonic day (E)16 in the maxillary sinus component of the lateral nasal glands. The abundance of mRNA and protein in the lateral nasal glands increased with age and reached a peak at postnatal day (P)27. Also at P27, vomeromodulin mRNA and protein expression was initiated in vomeronasal glands and posterior glands of the nasal septum. Comparison of the developmental expression of odorant‐binding protein, another carrier protein synthesized in the lateral nasal glands, with that of vomeromodulin demonstrated major differences. In contrast to vomeromodulin, odorant‐binding protein was not detected until postnatal day 2 in the ventral component of the lateral nasal glands and anterior glands of the nasal septum. These results suggest that the expression of vomeromodulin and odorant‐binding protein is developmentally and differentially regulated and confirms the suggestion that vomeromodulin may function in olfactory and vomeronasal perireceptor processes as a transporter for pheromones and odorants. In addition, the embryonic expression of vomeromodulin suggests its involvement in olfactory perireceptor processes in utero. © 1995 Wiley‐L

ISSN:0360-4012    

DOI:10.1002/jnr.490400107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractProlonged iontophoretic administrations of δ‐ and μ‐selective opioid receptor agonists were conducted in the hippocampus of rats, in order to study the possible development of acute tolerance to the excitatory effects of the opioids. Acute tolerance (AT) to the excitatory effects of the 8‐selective opioid receptor agonist Tyr‐D‐Ser‐Gly‐Phe‐Leu‐Thr (DSLET) was observed when the drug was applied locally for 3–5 min in the CA1 hippocampal pyramidal neurons. The acute tolerance was expressed as a decrease in the commissurally evoked spike responsiveness during peptide's administration and led to a long‐lasting potentiation of the population spike (PS) upon its withdrawal. In all cases, where AT and spike potentiation were evident, the population excitatory postsynaptic potential (pEPSP) remained unaltered. Pharmacological studies of AT and long‐lasting spike potentiation showed the following: (1) the non‐selective opioid receptor antagonist, naloxone, while effective in blocking the excitatory effects of DSLET when applied prior and during the application of the latter, failed to exhibit and effect on the long‐lasting potentiating effect of the opioid; and (2) during the spike potentiation phase, administration of DSLET exhibited a depressant effect towards baseline values. This depressant effect of the opioid was evident 2–3 min from the beginning of the application and was completely antagonized by naloxone. The above results show that the development of acute tolerance to the excitatory effects of the DSLET led to long‐lasting spike potentiation, which manifests a withdrawal p

ISSN:0360-4012    

DOI:10.1002/jnr.490400108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractNF‐66, also known as α‐internexin, has been characterized as a 66 kD mammalian neurofilament (NF) protein whose expression in developing rat brain precedes that of the low molecular weight NF protein (NF‐L). NF‐66 is thought to assemble into 10 nm diameter intermediate filaments in vitro, although the precise nature of the assembly process remains obscure. Likewise, the ability of NF‐66 to polymerize with the low (NF‐L), middle (NF‐M), and high (NF‐H) MrNF proteins has not been defined. This investigation describes the reassembly of bovine NF‐66 regarding its formation into 10 nm diameter filaments as well as its potential for polymerization with other type IV intermediate filaments. NF‐66 and the NF triplet proteins were isolated from bovine spinal cord using established biochemical extraction and isolation procedures (Balin et al., Brain Res 556:181–195, 1991), and purified by a combination of high performance liquid chromatography (HPLC) (DEAE anion exchange and hydroxylapatite column chromatography) and gel elution strategies. In vitro reassembly experiments revealed that NF‐66 formed ˜ 10 nm diameter filaments of varying length; immunoelectron microscopy demonstrated labeling of these filaments by a monoclonal antibody to intermediate filament antigen (IFA), a polyclonal antibody against rat NF‐66 and by a monoclonal antibody generated against the core region of NF‐M but cross‐reactive with NF‐66. This report is the first investigation to look at the in vitro interaction between NF‐66 and other type IV intermediate filament proteins (NF‐H, ‐M, and ‐L) and establishes that NF‐66 forms heteropolymeric filaments with these other neurofilament proteins, as confirmed by double immunolabeling. These studies suggest that NF‐66 could provide a nucleation site for the polymerization of later‐expressed proteins duri

ISSN:0360-4012    

DOI:10.1002/jnr.490400109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractInduced release of endogenous dopamine and noradrenaline from coronal slices containing the striatum and the bed nucleus of the stria terminalis, respectively, was studied by means of in vitro microdialysis. A Ca+2‐dependent and reserpine‐sensitive K+‐induced release of catecholamines was detected in both nuclei. We confirmed that N‐methyl D‐aspartate (2.5 and 5.0 mM in the dialysis perfusion solution) induces the release of dopamine from the striatum, and this effect was blocked by prior dialysis perfusion with 500 μM MK‐801, a noncompetitive N‐methyl‐D‐aspartate receptor antagonist. Infusion of N‐methyl‐D‐aspartate (1–10 mM) or glutamate through the dialysis probe did not produce any detectable modification in the extracellular levels of noradrenaline in the bed nucleus of the stria terminalis. In addition, perfusion with D‐serine (100 μM)alone or in the presence of desipramine (10 μM) resulted in a slight increase in extracellular noradrenaline in the bed nucleus of the stria terminalis. However, N‐methyl‐D‐aspartate in the presence of D‐serine and desipramine produced a marked increase in extracellular noradrenaline from the bed nucleus of the stria terminalis. These results indicate that N‐methyl‐D‐aspartate receptors might regulate the release of noradrenaline from the bed nucleus of the stria terminalis as is the case of dopamine release in the striatum. The in vitro microdialysis seems to be a suitable complement to the in vivo microdialysis for the study of catecholamine release in discrete regions of the central nervous system and its local regulation by excitatory

ISSN:0360-4012    

DOI:10.1002/jnr.490400110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractMacrophages play critical roles in both degenerative and regenerative processes following peripheral nerve injury. These include phagocytosis of debris, stimulation of Schwann cell dedifferentiation and proliferation, and salvage of myelin lipids for reutilization during regeneration. To better define the role of macrophages, we studied models of primary demyelination (tellurium intoxication) and secondary demyelination (nerve crush and cut). Sections of paraformaldehyde‐fixed rat sciatic nerves at various stages of demyelination were stained with monoclonal antibody ED1, a standard macrophage marker, and a polyclonal antiserum specific for lysozyme (LYS). Near the peak of demyelination in all three models, LYS immunoreactivity colocalized with ED1 staining. Macrophages present in nerve after the period of maximal phagocytosis of myelin were much less immunoreactive for LYS. These results suggest LYS is a good marker for macrophages which are active in phagocytosis. Tellurium intoxication, which causes synchronous demyelination and subsequent remyelination of only about 25% of myelin internodes, recruited more macrophages (and induced more lysozyme expression) than either nerve crush or cut, which cause demyelination of all internodes distal to the injury site. This suggests that Schwann cells may recruit macrophages soon after metabolic insult and prior to actual demyelination. The final signal for macrophage recruitment is not directly related to the amount of damaged myelin. In the models listed above, steady state mRNA levels for apolipoprotein E (ApoE; possible mediator of cholesterol salvage), LYS, and Po (major structural protein of PNS myelin), were analyzed by Northern blot analysis. LYS mRNA levels peaked sharply in all models, with a temporal pattern consistent with the expected presence of activated, phagocytic macrophages. The temporal pattern for ApoE mRNA levels differed in the 3 models, but ApoE expression was consistent with its proposed role in salvage of cholesterol during remyelination. © 1995 Wiley‐Liss,

ISSN:0360-4012    

DOI:10.1002/jnr.490400111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY