摘要:

AbstractThe distribution of 110/140 laminin‐binding protein (110/140 LBP) in the spinal dorsal root ganglia (DRG) and its regulation by partial constriction of the sciatic nerve was studied in adult rats. The cross‐sectional area of neurons with 110/140 LBP‐immunoreactivity (−I) showed an approximately normal frequency distribution. The 110/140 LBP‐I was observed in neuronal cell bodies exclusive of the nucleus. Following sciatic nerve constriction, the 110/140 LBP‐I was downregulated in the ipsilateral L4‐5 DRG. DRG neurons with a cross‐sectional area ≥ 1600 μm2were preferentially affected. Neonatal capsaicin‐treatment, a procedure that selectively destroys a subpopulation of DRG neurons with fine unmyelinated axons, had no effect on the reduction of 110/140 LBP in the DRG induced by sciatic nerve constriction. Western immunoblot analysis confirmed a reduction of 110/140 LBP on the side ipsilateral to the constriction. These results demonstrate a LBP within primary sensory neurons and its suppression by peripheral nerve injury. The data support a role for LBP in the adult nervous system.© 1993 WiIey‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the U

ISSN:0360-4012    

DOI:10.1002/jnr.490350302

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

年代:1993

数据来源: WILEY

摘要:

AbstractProlonged depolarization of isolated, voltageclamped skate retinal horizontal cells produces an outward current that exhibits a late onset and develops slowly with time. This current, which we refer to as the Q‐current, is associated with an increase in membrane conductance, and is present when other voltage‐gated conductances have been pharmacologically blocked. The reversal potential for the Q‐current, obtained using tail current analysis, was close to 0 mV. The magnitude of the current was greatly reduced by superfusion with 25 mM acetate, and by 4 mM cobalt chloride, 2 mM 1‐octanol, and a saturated solution of the general anesthetic halothane. In addition, the low‐molecular weight fluorescent dye Lucifer yellow, applied extracellularly, entered the cells during activation of the Q‐current, whereas a 3 kD dextran‐fluorescein complex did not cross the cell membrane. The effects of divalent cations, the nonspecific nature of the ionic current suggested by its reversal potential, the entry of Lucifer yellow, and the ability of acetate, halothane, cobalt, and octanol to block the current lead us to hypothesize that the Q‐current results from the opening of hemi‐gap junctional channels that mediate electrical coupling between skate horizontal cells. © 19

ISSN:0360-4012    

DOI:10.1002/jnr.490350303

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

年代:1993

数据来源: WILEY

摘要:

AbstractRadioligand binding, Northern blot analysis, and changes in [Ca2+]i were used to study serotonin [5‐hydroxytryptamine (5HT)]receptor subtypes in primary cultures of astrocytes from neonatal rat cerebral cortex. Radioligand binding studies revealed the presence of 5HT2, but not the 5HT1or 5HT3receptor subtypes. Radioligand binding was also used to show the presence of serotonin uptake sites, which had previously been shown to be present by [3H]‐5HT uptake, and also α1‐adrenergic receptors as has previously been reported by binding studies. Northern blot analysis of cortical astrocyte mRNA demonstrated the presence of transcripts for 5HT2receptors, but failed to identify mRNA for 5HT1αor 5HT1creceptors. Thus, results from Northern blot analysis correlated with the radioligand binding data which showed only 5HT2receptors. Equilibrium saturation studies, using125[I]‐LSD to label 5HT2receptors, yielded a KDof 9 nM and a Bmaxof 177 fmol/mg protein. Radioligand binding studies or primary astrocyte cultures prepared from other brain regions also showed the presence of α1‐ adrenergic, 5HT2receptor, and 5HT‐uptake sites, but no detectable 5HT1areceptors, which were the only 5HT1receptors studied. Studies demonstrating 5HT‐induced, spiperone‐ and ketanserin‐sensitive increases in free [Ca2+]i as measured by FURA‐2, showed that the 5HT2receptors were functional in these cells. These data provide clear evidence for the existence of both 5HT2receptors and 5HT‐uptake sites in the same primary astrocyte cultures from neonatal rat cerebral cortex, with no detectable evidence of 5HT1aor 5HT1csubtypes

ISSN:0360-4012    

DOI:10.1002/jnr.490350304

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe microtubule‐associated protein MAPIB is belieyed to play an important role in the outgrowth of neurites from neurons (Tucker and Matus, Dev Biol 130:423–434, 1988). We have investigated the possibility that MAPIB might participate in the formation of processes incultured oligodendrocytes by an anal‐ ysis of the expression of MAPIB during oligodendrocyte progenitor development. The appearance of the antigens recognized by the monoclonal antibodies A2B5, O4, and O1 which define distinct stages in the maiuration of progenitors, was compared with the developmental expression of MAPIB. MAPIB is first detectable in O4+preoligodendrocytes prior to the acquisition ofgalactocerebroside and immediately before they develop the complex process‐bearing mor‐ phology characteristic of terminally differentiated myelin‐forming oligodendrocytes in the CNS. In contrast, astrocytes have negligible amounts of MAP1B. These results demonstrate that the expression of MAP1B precedes the development of the mature oligodendrocyte phenotype and suggest that interactions between microtubules and MAP1B might have a role in the formation and stabilization of myelinforming processes. © 1993 Wil

ISSN:0360-4012    

DOI:10.1002/jnr.490350305

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

年代:1993

数据来源: WILEY

摘要:

AbstractWe have previously demonstrated that systemic administration of testosterone differentially regulates the regenerative properties of injured hamster facial motor neurons, which are androgen receptor‐containingcranialmotor neurons. In this investigation the hypothesis that testosterone alters the regenera‐ tive properties of rat sciatic motor neurons, which are androgen receptor‐containingspinalmotor neurons, was tested using fast axonal transport of radioactively labeled proteins to assess sciatic nerve regeneration. Adult castrated male rats were subjected to crush axotomy of the sciatic nerve at the level of the gemelli tendons (mid‐thigh). One‐half of the axotomized animals received subcutaneous implants of testosterone propionate (TP), with the remainder of the animals sham implanted with blank capsules. The outgrowth distances of the leading axons were measured at 5, 6, 7, and 11 days postoperative. Linear regression analysis was accomplished, with the slope of the line representing the regeneration rate and the x‐intercept the initial delay of sprout formation. Systemic administration of testosterone resulted in a 13% increase in the rate of regeneration, relative to the control, –TP group. Outgrowth distances were significantly increased in the 4‐ TP group only in the later stages of regeneration. However, TP did not shorten the delay in sprout formation in regenerating sciatic motor neurons, but instead produced a small prolongation in the delay time. This pattern of hormonal regulation of the regenerative properties of spinal motoneu‐ rons is similar to that previously found in cranial motoneurons. The prolongation of the initial delay may have been a factor in the lack of significant outgrowth distances during the early stages of regeneration. The magnitude of the effects of TP on male rat sciatic motor neurons are less pronounced than in male hamster facial motor neurons, but quite similar to those effects observed in female hamster facial motor neurons. Why this is the case is not known, but may be related to a irumber of factors discussed in the text. © 19

ISSN:0360-4012    

DOI:10.1002/jnr.490350306

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

年代:1993

数据来源: WILEY

摘要:

AbstractThere are two morphologically distinct types of glial cells (i.e., ensheathing cells and astrocytes) in the nerve fiber layer (NFL) of the adult mammalian olfactory bulb. Ensheathing cells provide ensheathment for olfactory axons, whereas astrocytes occupy the interfascicular spaces of the olfactory NFL. During embryonic development, however, only one type of glial cell is found in this layer of the olfactory bulb, namely, the ensheathing cell. Even though ensheathing cells take up residence within the CNS, they are actually derived from the olfactory placode. Far less is known about the developmental origin of interfascicular astrocytes, which arise either from the glial progenitor cells that give rise to ensheathing cells or from astrocyte precursor cells that migrate into the NFL from deeper layers of the bulb primordium. In the present study, enriched populations of ensheathing cells were grown in vitro in media known to promote the growth and differentiation of astrocytes to determine whether ensheathing cell progenitors could differentiate into astrocytes. These media failed to induce the appearance of astrocytes in the ensheathing cell cultures. It was concluded that the astrocytes of the NFL most likely arise from progenitor cells that migrate into this layer from deeper parts of the developing bulb. © 1993 Wiley‐Liss, I

ISSN:0360-4012    

DOI:10.1002/jnr.490350307

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

年代:1993

数据来源: WILEY

摘要:

AbstractWe investigated the effects of increasing the concentration of intracellular cyclic adenosine monophosphate (cAMP) on genes associated with oligodendrocyte differentiation in an immortalized glial cell line, 6E12, derived from the spinal cord of an MBP‐SV40 large T‐antigen transgenic mouse. Raising intracellular levels of cAMP induced expression of oligodendrocyte differentiation antigens recognized by O4 and anti‐galactocerebroside antibodies, up‐regulated expression of the proteolipid protein (PLP) gene, and down‐regulated glial fibrillary acidic protein (GFAP) expression. There was no treatment effect on myelinassociated glycoprotein (MAG) expression. These phenotypic changes are consistent with oligodendrocyte differentiation. Treatment of 6E12 cells with dibutyryl cyclic AMP (DBC) down‐regulated myelin basic protein (MBP) gene expression, perhaps, because it also up‐regulated expression of a putative MBP repressor SCIP/Tst‐1. Moreover, the 6E12 cells expressed high levels of MBP mRNA but no MBP translation products were detected in the presence or absence of DBC. This immortalized glial cell line is proposed as a CNS model for cAMP‐modulated myelin gene expression and for post‐transcriptional regulation of MBP. ©

ISSN:0360-4012    

DOI:10.1002/jnr.490350308

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe production of collagen‐degrading proteases by cultured neonatal rat microglia was examined using an immobilized fibronectin‐gelatin matrix coupled to a fluorescent marker and by substrate gel analysis. When microglia were plated onto the surface of the matrix and incubated under resting (nonstimulated) conditions, a small but visible amount of immobilized matrix was degraded. Treatment with lipopolysaccharide (LPS) or interleukin‐1 (IL‐1) significantly increased the number of microglia demonstrating substrate degradation. Substrate‐SDS polyacrylamide gel electrophoresis of samples of supernatants from untreated cultured microglia indicated the presence of a 72 and a 92 kD metalloproteinase with characteristics corresponding to collagenases. Supernatants from untreated astrocyte cultures were shown to have primarily a 72 kD metalloproteinase. Proteinase activity increased on stimulation of the microglia with LPS and IL‐1 in a dose‐dependent fashion. These results indicate that cultured microglia release active proteases capable of degrading the extracellular matrix in a localized region. The production of proteases by activated microglia may have important physiological and pathophysiological consequences within the restricted extracellular matrix of the CNS. © 1993 W

ISSN:0360-4012    

DOI:10.1002/jnr.490350309

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

年代:1993

数据来源: WILEY

摘要:

AbstractInterleukin(IL)‐2 supported the survival and enhanced neurite extension of cultured hippocampal neurons prepared from embryonic 18‐day‐old rats. This neurotrophic effect was observed at concentrations of 2 to 200 U/ml, and almost all the neurons could survive for more than 2 days in the presence of 200 U/ml of IL‐2. This viability‐promoting effect of IL‐2 on the neurons was completely blocked with anti‐IL‐2 antibodies. IL‐2 also supported the survival of cultured cortical, striatal, and septal neurons. These results indicate that IL‐2 has a survival‐promoting effect on a wide variety of neurons. On the other hand, IL‐2 did not affect the choline acetyltransferase (ChAT) activity of striatal neurons, suggesting that this cytokine does not act as a differentiation factor for striatal cholinergic neurons.

ISSN:0360-4012    

DOI:10.1002/jnr.490350310

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

年代:1993

数据来源: WILEY

摘要:

AbstractPermanent cell lines from human neuroblastoma, a sympathoadrenal malignancy, are known to exhibit a more neuronal phenotype characterized by outgrowth of long processes in response to multiple second messenger analogs. In this report we demonstrate that the 38‐amino acid form of a peptide homologous to vasoactive intestinal peptide (VIP), pituitary adenylate cyclase activating peptide (PACAP), as well as the 27‐amino acid form of PACAP, induce NB‐OK human neuroblastoma cells to extrude cellular processes within 5 hr of treatment with either peptide at 10−8M. Treatment of NB‐OK cells with PACAP38 or PACAP27 at 10−8M for 1 hr also elevates cAMP content greater than 100‐fold and inositol lipid turnover 11‐ to 12‐fold. VIP acutely induces process outgrowth and elevates intracellular second messenger levels in NB‐OK cells only at higher concentrations, 10−6M or greater. In contrast to the equipotency of PACAP27 and PACAP38 in stimulating the outgrowth of processes observed after 5 hr of treatment, PACAP38 is much more potent than PACAP27 when NB‐OK cells are scored for process outgrowth after 72 hr of treatment. Correlating with the extended time course over which morphologic changes are seen with PACAP38, cAMP levels remain elevated for a more prolonged time span during treatment with PACAP38 than PACAP27. After 72 hr of treatment with PACAP38 versus treatment with PACAP27, cAMP levels are elevated 10‐fold versus 3‐fold, respectively. PACAP38 at 10−8M also induces process outgrowth in two additional human neuroblastoma lines tested, SMS‐KAN and LA‐N‐1, whereas PACAP27 and VIP at the same concentration are less effective. The effects of PACAP38 on neuroblastoma cells may be a model for neurotrophic activities of PACAP38 via G protein‐linked intracellular messengers in human sympatho

ISSN:0360-4012    

DOI:10.1002/jnr.490350311

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

年代:1993

数据来源: WILEY