bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regional variation in the abundance of axonal cytoskeletal proteins
Authors: Watson D. 
Published: January 2005

AbstractThe relative abundance of several axonal cytoskeletal proteins was determined by immunoassay at various sites in the peripheral and central nervous systems of adult rats. Within the peripheral nervous system, the ratio of tubulin to neurofilaments was greatest for nerves composed of unmyelinated axons and least for nerves with large myelinated axons. MAP1 protein was more prominent in unmyelinated fibers; conversely tau proteins were relatively more abundant in large myelinated axons. An immunochemical index of neurofilament phosphorylation was less for unmyelinated fibers than for myelinated ones.In the fimbria‐fornix, pyramidal tract, and superior cerebellar peduncle, similar trends were observed: small axons had more MAP1, less tau, and a greater ratio of tubulin to neurofilament proteins. The phosphorylation index was greatest for the superior cerebellar peduncle, the tract with the largest axons. The immunochemical index of neurofilament phosphorylation was greater for the optic nerve than for axonal tracts in the brain proper. These results suggest that development of large myelinated axons is associated with greater neurofilament content, neurofilament phosphorylation, and with greater abundance of tau proteins in the CNS and the PNS; however, quantitative aspects of these relationships differ in the PNS and the CNS.
Induction of tyrosine hydroxylase in the rat substantia nigra by local injection of forskolin
Authors: Leviel V. , Guibert B. , Mallet J. , Faucon‐Biguet N. 
Published: January 2005

AbstractForskolin (FSK) was locally injected into the substantia nigra (SN) of anesthetised rats. The day after injection (24 and 36 hr), tyrosine hydroxylase (TH) activity increased locally in this structure but remained unmodified in the ipsilateral caudate nucleus (CN). The amount of messenger RNA for TH (TH‐mRNA) was also increased in the SN 24 hr after the injection. However, TH protein content was modified neither locally in the SN nor in the ipsilateral CN. In addition, the decrease of the ratio between dopamine and its first metabolite in the CN and the SN suggested a decreased activity of the dopaminergic nigral cells. The absence of increase of the protein synthesis in spite of the fact that TH‐gene transcription was initiated could be the consequence of the inhibition of dopaminergic cells by the drug. These results confirm that, in vivo, TH induction is cAMP‐dependent and demonstrate that the TH‐gene activity is not strictly coupled to the activity of dopaminergic cells in the SN.
Adenosine‐dependent regulation of cyclic AMP accumulation in primary cultures of rat astrocytes and neurons
Authors: Murphy M. G. , Moak C. M. , Byczko Z. , MacDonald W. F. 
Published: January 2005

AbstractThe regulation of intracellular cyclic AMP (cAMP) formation by adenosine (Ado) and its analogues has been examined in primary cultures of rat‐brain astrocytes and neurons. In the presence of the phosphodiesterase inhibitor, Ro 20‐1724, basal levels of cAMP ranged from 40–120 pmol/mg protein in both cell types. Levels were not altered by treating the cells with Ado deaminase, which suggested that they did not produce appreciable amounts of endogenous Ado under standard culture conditions. In the astrocytes, μM quantities of agonists increased cAMP up to 30‐fold higher than basal values; the relative potencies were typical of an A2 Ado receptor (NECA > Ado > R‐PIA). Neuron‐enriched cultures exhibited a maximum fourfold increase in cAMP in response to NECA; this was decreased a further eightfold when the cultures had prolonged exposure to the antimitotic agent, c‐Ara, to eliminate >98% of the nonneuronal cells. Low (nM) amounts of the Ado agonists inhibited cAMP formation in both cell types. In the astrocytes, the order of potency of inhibition of isoproterenol‐stimulated cAMP formation was typical of an A1 receptor (R‐PIA > Ado > NECA); maximum inhibition was 55–65%. Isoproterenol did not increase cAMP in the neuronal cultures. However, forskolin‐stimulated formation was effectively (∼50%) inhibited by A1 Ado agonists; inhibition was not affected by prolonged treatment with c‐Ara. From this study we tentatively concluded that rat astrocytes and neurons both contain inhibitory A1 Ado receptors, but that the stimulatory “A2” subtype is localized mainly on astrocytes.
Nicotinic and muscarinic subtypes in the human brain: Changes with aging and dementia
Authors: Nordberg A. , Alafuzoff I. , Winblad B. 
Published: January 2005

AbstractDifferent effects of normal aging on muscarinic and nicotinic receptor subtypes were observed in postmortem brain tissue from different regions of the human brain. A significant decrease in Ml and M2 receptors was found in cerebral cortex, while the Ml and especially the M2 receptors increased with age in the thalamus. A similar pattern of changes was also observed when using (−)3H‐nicotine as ligandfor nicotinic receptors in the cortex and thalamus. No significant changes in nicotinic receptor binding were observed with age in the cortex or thalamus, when using 3H‐acetylcholine as ligand. Nicotinic and muscarinic receptors in the brain are not equally affected in dementia disorders. A marked loss of high affinity nicotinic receptors was observed in cortical tissue from patients with Alzheimer's disease and with multi‐infaret dementia (MID). The muscarinic receptors were (both Ml and M2) increased in Alzheimer cortical tissue while they were decreased in MID.
Collagen IV is present in the developing CNS during Drosophila neurogenesis
Authors: Mirre C. , Le Parco Y. , Knibiehler B. 
Published: January 2005

AbstractBy means of immunocytochemistry with a battery of specific antibodies, we describe the expression of the collagen IV chain produced by the gene DCgl during the two phases of Drosophilaneurogenesis. DgC1 was not expressed in neuronal tissues as shown by in situ hybridization, but the onset of its expression in cells of mesodermal origin was concomitant with the appearance of collagen IV on early axon pathways and peripheral nerve roots in the embryonic developing CNS. A similar situation was found during imaginal CNS development at metamorphosis, when collagen IV immunoreactivity was detected on centrifugal and centripetal nerve pathways, and specially on retinula axons that develop from the eye imaginal disc towards the lamina anlage in the brain optic lobe. Our results strongly suggest that collagen IV could be involved, together with other informative molecules of basement membranes, in a dynamic process of cell‐matrix interactions during the establishment of initial axon pathways and neurite outgrowth in vivo.
Analysis of promoter activity and 5′ genomic structure of the neural cell adhesion molecule L1
Authors: Kohl A. , Giese K. P. , Mohajeri M. H. , Montag D. , Moos M. , Schachner M. 
Published: January 2005

AbstractTo gain insight into the molecular mechanisms underlying the regulation of expression of the neural cell adhesion molecule L1 and into the exon–intron structure of the L1 gene, a genomic clone from the mouse was characterized. The clone was identified by screening an EMBL3 library with an L1‐specific cDNA probe and comprises approximately 15 kb, in which the first 2,206 nucleotides of the coding region are included. Of the 5 of 6 immunoglobulin (Ig)‐like domains sequenced, all are encoded by 2 exons, with the first exon being smaller than the second. The exon encoding the signal peptide is separated from a mini‐exon containing 15 bp by a large intron, approximately 2.6 kb in length, whereas the other introns are smaller, with the coding information for the Ig‐like domains 3–5 clustered in a 1,643‐bp‐long fragment with introns only 110–217 bp in length. The 5′ upstream region of the clone comprises 5 kb, with the first 112 bp lying upstream to the coding sequence and containing a start site for transcription. No consensus sequence for a TATA box was found. Consensus DNA sequences for the binding of the gene products of Hox 1.3, engrailed and bicoid, are localized upstream to the transcription start site. A 1,262‐bp fragment containing part of the first exon showed promoter activity in neuroblastoma cells, but hardly in L cells and not in CHO cells, indicating that this fragment is sufficient for neural cell directed promoter activity. © 1992 Wiley‐Liss, Inc.
Novel stage in the oligodendrocyte lineage defined by reactivity of progenitors with R‐mAb prior to O1 anti‐galactocerebroside
Authors: Bansal R. , Pfeiffer S. E. 
Published: January 2005

AbstractThe developmentally regulated appearance of surface immuno‐reactivity of proligodendroblasts [oligodendrocyte progenitors reacting with monoclonal antibodies A007 and O4, but not anti‐galactocerebroside (GalC), i.e., A007/O4+ GalC−] to monoclonal antibodies R‐mAb and O1 was studied both in culture and in vivo. In both cases staining with R‐mAb shortly preceded that with O1; that is, a transient population of R‐mAb+ O1− cells was observed. R‐mAb− O1+ cells were not detected. Differential staining with R‐mAb and O1 was also noted at the subcellular level. In younger cultures in which R‐mAb+ cells were first acquiring O1 immunoreactivity, many of these cells were stained by O1 only on the cell bodies and proximal portions of the processes, whereas in contrast R‐mAb stained the whole cell, including the distal portions of the processes. Only in older, more mature R‐mAb+ cells did O1 also stain the distal portions of processes. The expression of reactivity to R‐mAb and O1 was compared to the proliferative capacity of the cells. Proliferation [assessed by bromodeoxyuridine (BrdU) incorporation] of both R‐mAb+ and O1+ cells was negligible both in culture and in vivo. However, treatment of cells in culture with 10 ng/ml basic fibroblast growth factor resulted in an enhancement of proliferation of the R‐mAb+ cells. Within the proliferating R‐mAb+BrdU+ population, 80% of the cells were O1− (i.e., anti‐galactocerebroside negative). These events occur during a critical period of development when A007/O4+ proligodendroblasts begin to become post‐mitotic and express surface galactocerebroside. The data demonstrate that the use of R‐mAb as an “anti‐GalC” must be interpreted with caution, and indicate the utility of dual staining with R‐mAb and O1 to (1) further subdivide the oligodendrocyte lineage, thus identifying an additional, GalC− developmental compartment, and (2) observe the distribution of R‐mAb and O1 immunoreactivity at a subcellular level. © 1992 Wiley‐Liss, Inc.
Immunocompetent cell markers in human fetal astrocytes and neurons in culture
Authors: Ennas M. G. , Cocchia D. , Silvetti E. , Sogos V. , Riva A. , Torelli S. , Gremo Fulvia 
Published: January 2005

AbstractDuring the past few years, evidence has accumulated that interaction with peripheral immune cells as well as immunoregolatory functions in the central nervous system (CNS) can be played by several types of brain resident cells. Since very little information is available in man, however, we investigated the presence of markers so far considered typical of immunocompetent cells in in vitro cultures of human fetal brain. Immunocytochemistry at the light, scanning, and transmission electron microscopic levels revealed positivity for a very restricted range of macrophage antigens in astrocytes, which, however, were incapable of phagocytosis. In particular, expression of the major histocompatibility complex–class II antigen HLADR was observed in the cytoplasm and on the cell surface of GFA‐P+ astrocytes and increased with time in culture and cell passages. Among the T‐lymphocyte markers tested, Thy.1 and CD4 were positive. Both neurons and astrocytes carried Thy.1 from early cell passages. Noteworthy was the presence of CD4, which serves as the receptor for AIDS virus, in neurons from the first 2 weeks, whereas astrocytes became positive after only 4–6 weeks. Even if most staining was in the cytoplasm, some was exposed on cell surface. Astrocytes were found positive for the B‐lymphocyte marker CD21, the cellular receptor for Epstein‐Barr virus, whereas CD24 was detected in both neurons and astrocytes. Both antigens are related to B‐cell proliferation. Results are in favour of the hypothesis of human brain cells being actively involved in CNS immunological events. © 1992 Wiley‐Liss, Inc.
Endogenous aFGF expression and cellular changes after a demyelinating lesion in the spinal cord of adult normal mice: Immunohistochemical study
Authors: Tourbah A. , Baron‐van Evercooren A. , Oliver L. , Raulais D. , Jeanny J. C. , Gumpel M. 
Published: January 2005

AbstractFibroblast growth factors (FGFs) are known to act on glial cells in vitro. At the present time, their involvement in the remyelinating process of the adult central nervous system (CNS) is still unknown. In the present study, using immunohistochemistry (IHC), we investigated the evolution in time and space of acidic FGF (aFGF) expression and CNS cell changes occurring after a chemically induced demyelinating lesion. In a first early period, aFGF immunostaining was shown to decrease around the demyelinated area. A dramatic increase was then observed and was accompanied by an increase of cell density around and inside the lesion. This was correlated with the beginning of remyelination. Late after demyelination, while remyelination was still in progress, aFGF immunostaining of the lesion and unlesioned spinal cord were comparable. A role of aFGF in remyelination is proposed. © 1992 Wiley‐Liss, Inc.
Differential expression of carboxyl terminal derivatives of amyloid precursor protein among cell lines
Authors: Wolozin B. , Bacic M. , Merrill M. J. , Lesch K. P. , Chen C. , Lebovics R. S. , Sunderland T. 
Published: January 2005

AbstractUnderstanding the pathway for amyloid precursor protein (APP) catabolism has become an important line of investigation. APP is a ubiquitous membrane bound protein that is rapidly cleaved at the membrane, yielding a secreted protein identical to protease nexin II and an internalized 11.5 kDa 100 residue C terminal derivative (CTD). The levels of CTDs in a variety of cell lines have been examined and were found to differ. Cell types associated with the pathology of Alzheimer's disease (AD), such as olfactory neuroblasts (ON) and cortical vascular endothelial cells, have higher levels of CTDs than lymphoblasts and melanoma cells. The mechanism of CTD catabolism appears to involve the lysosome because blockade of lysosomal but not endosomal or mitochondrial function results in increased levels of CTDs. Under these conditions, production of larger, amyloidogenic CTDs is also seen. In cells possessing higher levels of CTDs we find that the mechanism for production of amyloidogenic CTDs may involve the internalization of intact full‐length APP. Thus, inhibition of the lysosomal system appears capable of generating amyloidogenic peptides. The amount of amyloidogenic peptides appears to vary among cell lines. Such variation may shed light on why amyloid accumulates around specific cell types such as vascular endothelial cells, neurons, and glia. Finally, disfunction of the lysosomal system may play a role in the pathogenesis of Alzheimer's disease. © 1992 Wiley‐Liss, Inc.
Altered genetic response to β‐adrenergic receptor activation in late passage C6 glioma cells
Authors: Gubits R. M. , Yu H. , Casey G. , Munell F. , Vitek M. P. 
Published: January 2005

AbstractPrevious studies have demonstrated variability in the phenotype of rat C6 glioma cells. In the present study, we compared morphology, growth rate, and β‐adrenergic regulation of gene expression in early (P39–47) and late (P55–90) passage C6 cells. Morphological changes were observed in five independently derived, late passage populations. In four of the five, the untreated cells were more polygonal than the fibroblast‐like parental cells, and only a small fraction exhibited process outgrowth after dbcAMP treatment. Untreated cells from the fifth late passage population had longer cytoplasmic processes than parental cells and responded to dbcAMP with further process outgrowth. All late passage populations had shorter generation times than the parental cells. In early passage cells, treatment with the β‐adrenergic agonist, isoproterenol (IPR), resulted in an increase in c‐fos mRNA and a decrease in c‐jun mRNA (Gubits RM, Yu H: J Neurosci Res, 30:625–630, 1991). Both of these immediate early gene responses were irreversibly lost between P50 and P55. Additional differences in basal or IPR‐induced mRNA levels were observed for β‐APP, GFAP, NGF, and PPE, but not for a number of other mRNAs. These results are discussed in relationship to previously described differences in the ability of early and late passage C6 cells to accumulate cAMP (Mallorga P, et al.: Biochim Biophys Acta 678:221–229, 1981). © Wiley‐Liss, Inc.
Metabolic relationships between proteins of myelin and paranodally shedded, partially degraded myelin fragments in the rabbit CNS
Authors: Persson H. , Berthold C.‐H. , Rydmark M. , Fabricius C. 
Published: January 2005

AbstractThe “close‐to‐node” regions of myelinated nerve fibres, i.e., the paranodal end segments, are generally thought to be sites of high metabolic activity and myelin sheath turnover. Data on turnover rates of individual myelin constituents are conflicting but there exists a common belief that myelin is metabolized as independent molecules rather than as a unit. The occurrence of paranodal Marchi‐positive bodies, with morphological and biochemical properties consistent with partially degraded myelin, prompted us to examine the temporal dynamics of the incorporation of radioactive precursor label in the major proteins of myelin and the Marchi‐positive bodies. 3H‐leucine was administered intrathecally in adult rabbits. After various survival times, the spinal cord was subfractionated by ultracentrifugation in a discontinuous two‐step 0.32 M/0.85 M sucrose gradient. Myelin was collected from the interface and a floating fraction, heavily enriched in Marchi‐positive bodies, was recovered on top of the 0.32 M sucrose. By scintillation counting and by gel fluorography combined with immunoblotting, a gradual appearance with time of partially degraded peptides of myelin‐associated protein and 2′,3′‐cyclic nucleotide 3′‐phosphodiesterase was seen in the floating fraction but not in myelin. The temporal dynamics of the specific activities of these two proteins and myelin‐basic protein and proteolipid protein were consistent with a typical source‐product relationship between myelin and the material in the floating fraction. In conjunction with earlier morphological and biochemical findings, these data may suggest that Marchi‐positive bodies appear as a consequence of myelin catabolism. © Wiley‐Liss, Inc.
Targeting of gonadotropin‐releasing hormone axons from preoptic area grafts to the median eminence
Authors: Saitoh Y. , Gibson M. J. , Silverman A.‐J. 
Published: January 2005

AbstractImplantation of normal GnRH neurons can reverse many of the reproductive deficiencies that characterize hypogonadal (hpg) mice. Since the GnRH axons follow a stereotyped trajectory to their target we investigated the possibility that host brain regions adjacent to the graft might provide signals that induced this directional growth. The role of the adenohypophysis in GnRH axonal outgrowth was studied in mice with co‐grafts of fetal preoptic area (POA) and pituitary and in hypophysectomized hosts. When fetal pituitaries were grafted together with the POA, immunoreactive GnRH fibers did enter the glandular tissue but they also grew into the host median eminence. Surgical removal of the pituitary of hpg hosts prior to POA graft placement was also compatible with GnRH innervation of the host median eminence although in some individuals that innervation pattern was confined to the more caudal aspects. The results of these two experiments suggest that the anterior pituitary gland may be an attractive target for GnRH axons but that this tissue is not essential for directed GnRH axonal outgrowth to its target.To determine if the median eminence itself could direct the growth of GnRH axons, co‐grafts of POA and a fetal medial basal hypothalamic (MBH) block, which was predominantly median eminence, were made. Immunocytochemistry showed that an intragraft mini‐median eminence was formed with a highly organized and robust GnRH innervation. Ultrastructural analysis indicated that these axons terminated near fenestrated capillaries. However, even under these conditions some GnRH axons exited into the host median eminence. It now seems likely that a cellular component of the median eminence can provide a signal to attract GnRH axons. Whether this signal is produced by the specialized ependymal cells, by the endothelia, or by meningeal (pial) components must now be tested. © 1992 Wiley‐Liss, Inc.
Amygdala neurons in vitro: Neurite growth and effects of estradiol
Authors: Lorenzo A. , Díaz H. , Carrer H. , Cáceres A. 
Published: January 2005

AbstractDissociated cell cultures from embryonic rat medial amygdala were studied using sequential photography and immunocytochemical staining for cytoskeletal proteins and substance P (sP). Cultures were seeded with cells taken from fetuses grouped by sex; experimental cultures were raised in medium containing 17‐beta‐estradiol (E2). Forty‐eight hours after plating a few neurons begin to define their morphological polarity by the differentiation of an axon‐like process; at 5 days in vitro (DIV) almost all neurons had developed an axon. Tapering, daughter branch ratio and branch power coefficient coincided with identification of dendrites which could be confirmed by retrospective analysis of immunocytochemically stained cultures: at 5 DIV MAP‐2 was restricted to dendrites whereas Tau immunoreactivity was differentially localized with a clear predominance in the axon. At 21 DIV neuronal shape parameters were strikingly like those of amygdaloid neurons in vivo. It was demonstrated in living neurons that E2 increased total dendritic length and that this is due to increased ramification of third or higher order dendritic segments whose individual lengths are not different from controls. Densitometric measurement of MAP‐2 stained neurons showed a highly significant increase of immunoreactive material in cells grown in the presence of E2; readings for alpha‐tubulin were not different between controls and E2 treated cultures. The effect of E2 on dendritic length was just as manifest in sP‐positive as in sP‐negative neurons. No sexual differences in morphological parameters, growth characteristics or effects of E2 were found in neurons taken from female fetuses versus neurons from male fetuses. The significance of these results for the generation of sexual differences in the amygdala in vivo is discussed and contrasted with reported results on the effects of E2 in cultures of different neural regions. © 1992 Wiley‐Liss, Inc.