bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of transferrin‐positive oligodendrocytes in the rat central nervous system
Authors: Connor J. R. , Fine R. E. 
Published: January 2005

AbstractTransferrin is the second most abundant plasma protein and functions to transport iron. It is an essential constituent in culture media for virtually all cells. In a recent study, we reported that transferrin (Tf) is specifically located in oligodendrocytes in the rat nervous system. This investigation examines immunohistochemically the development of Tf in the cerebral cortex, corpus striatum, and spinal cord. Tf is first seen in oligodendrocytes in the spinal cord white matter at 5 days of age. The immunoreactivity is confined to the white matter in the periphery of the spinal cord between 5 and 8 days of age. By 10–12 days of age, the number of immunoreactive oligodendrocytes in the spinal cord white matter increases considerably, corresponding to the onset of myelination. Tf‐positive oligodendrocytes are first found in the gray matter at 15 days of age. By 30 days of age, the number and distribution of Tf‐positive oligodendrocytes in both the brain and spinal cord have reached the adult pattern. The results of this study demonstrate a spatial and temporal association between Tf development and myelinogenesis. This suggests that part of the process of differentiation of oligodendrocytes includes the accumulation of Tf, perhaps in order to support the metabolic demands associated with the production and maintenance of myelin.
Regulation of sterol synthesis and of 3‐hydroxy‐3‐methylglutaryl coenzyme a reductase by lipoproteins in glial cells in primary culture
Authors: Langan T. J. , Iimori Y. , White G. , Volpe J. J. 
Published: January 2005

AbstractAlthough plasma lipoproteins have been demonstrated to have a major role in regulating cholesterol biosynthesis in extraneural cells, no data concerning such regulation are available for developing brain, when cholesterol synthesis is especially active. Glial primary cultures derived from neonatal rat brain and by morphological and biochemical criteria essentially exclusively composed of astrocytes were utilized to examine such regulation. When the primary cultures, which had been maintained in 10% fetal calf serum, were placed in 10% lipoprotein‐poor serum on day 7 of culture, an induction of sterol synthesis (1.6–2.2‐fold) and of 3‐hydroxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) reductase‐specific activity (1.5‐2‐fold) resulted after 24 hr. Addition of low‐density lipopro‐tein (LDL) to the 10% lipoprotein‐poor serum prevented the induction of both sterol synthesis and HMG‐CoA reductase. However, addition of high‐den‐sity lipoprotein (HDL) to the 10% lipoprotein‐poor serum caused a 1.5–2‐fold further induction of sterol synthesis relative to that in cultures containing 10% lipoprotein‐poor serum alone. In contrast to the glial primary cultures, cultures of C‐6 glioma cells responded to replacement of 10% fetal calf serum with 10% lipoprotein‐poor serum with much more marked increases of sterol synthesis and HMG‐CoA reductase. Although, as with the primary cultures, addition of LDL to the C‐6 glioma cell cultures prevented the increases in sterol synthesis and reductase activity, addition of HDL had no effect. Thus, these results indicate that in developing glial cells in primary culture, cholesterol synthesis and HMG‐CoA reductase are capable of responsiveness to both LDL and HDL. Moreover, at least in terms of regulation of sterol synthesis, C‐6 glioma cells and developing glia in primary culture clearly are not identical.
Experimental allergic encephalomyelitis (EAE): Role of B cell and T cell epitopes in the development of EAE in lewis rats
Authors: Hashim G. A. , Day E. D. , Carvalho E. , Abdelaal A. 
Published: January 2005

AbstractStudies from our laboratory have shown that classical clinical and histological signs of experimental allergic encephalomyelitis (EAE) may be induced in Lewis rats by synthetic peptides S49 or S55. Peptides S49S and S55S are defined by residues 69–84 and 72–84 of the guinea pig myelin basic protein (MBP), respectively. Peptide S53 (residues 75–84 of the guinea pig MBP), six residues shorter than S49S at the N‐terminal end, induced mild clinical signs of disease unaccompanied by hind leg paralysis, incontinence, or central nervous system pathology. In contrast, peptide S67 (residues 69–81 of the guinea pig MBP), three residues shorter than S49S at the C‐terminal end, did not induce either clinical or histological signs of EAE despite the fact that the S67‐sequence houses an epitope known to induce cell‐mediated immunity. Peptides S49S, S55S, and S53 are antigenic and gave rise to antibodies that recognized either of the three peptide sequences. In this report we explore the interrelationship between cellular immunity induced by the S67 sequence and humoral immunity, induced by the S53 sequence and the development of classical clinical and histological signs of EAE. The results show that the nonencephalitogenic sequence of S67 may be rendered encephalitogenic in the presence of antibody directed against the S53 sequence. Lewis rats immunized with S53 developed pathological signs of EAE only after they were challenged with S67. The fact that a simultaneous challenge with S67 and S53 was as effective in inducing EAE pathology as a delayed one (up to 40 days) suggests that the cellular response to S67 is dependent upon the humoral response to S53. The response to both peptides injected into separate sites mimics the response to the encephalitogenic S49S within which the S67 and the S53 sequences are subsumed. Clearly, a causal relationship is established between the humoral and cellular immunities in inducing EAE. This conclusion is supported by the results of the transfer experiments which showed that either anti‐S53 antibodies or S53‐primed lymphocytes may substitute for S53‐priming in potentiating the development of S67‐induced cell‐mediated immunity and therefore EAE pathology.
Arachidonic acid inhibits uptake of glutamate and glutamine but not of GABA in cultured cerebellar granule cells
Authors: Yu A. C. H. , Chan P. H. , Fishman R. A. 
Published: January 2005

AbstractThe effects of arachidonic acid (20:4) on the uptake of glutamate were studied in primary cultures of cerebellar granule cells and were compared to cortical neurons and astrocytes. At a dose of 0.005 mM, the glutamate uptake was significantly inhibited in cerebellar granule cells. This inhibition was dose and time dependent. The uptake of glutamate was equally sensitive to 20:4 in primary cell cultures of cortical neurons, whereas the uptake in astrocytes was much less sensitive to 20:4. Glutamine uptake was inhibited by 20:4 in cultured cerebellar granule cells and cerebral cortical astrocytes but was not affected in cerebral cortical neurons. Furthermore, the uptake of gammaaminobutyric acid was not affected by 20:4 in cerebellar granule cells.
Role of growth hormone in regulating T‐Dependent immune events in aged, nude, and transgenic rodents
Authors: Davila D. R. , Brief S. , Simon J. , Hammer R. E. , Brinster R. L. , Kelley K. W. 
Published: January 2005

AbstractGrowth hormone (GH) appears to play a major role in a reciprocal axis that has been postulated between the thymus and pituitary glands. Our previous studies showed that thymic structure, as well as T‐cell proliferation and IL‐2 synthesis, could be restored in aged female Wistar‐Furth rats by the implantation of GH3 pituitary adenoma cells. These cells secrete GH and some prolactin. We have now used three different approaches to determine whether GH affects a variety of immune events in vivo in both old and young rodents, and whether GH3 cells can directly affect progenitor T‐cells in nude rats that congenitally lack a thymus gland. To test the effects of GH in aged rats, 750 μg of pituitary‐derived ovine GH was injected 2× daily into 26‐month‐old Fischer 344 rats for 5 weeks. This approach demonstrated that GH augments splenocyte proliferation to T‐cell lectins as well as natural killer (NK) activity at low effector: target ratios even though morphologic characteristics of the thymus were not altered. To assess the effect of GH in young rodents, mice were studied that were transgenic for the rat metallothionein‐GH gene. Histologic evaluation of thymus glands revealed that the amount of adipose tissue and the number of epithelial cells and Hassall's corpuscles are augmented in transgenic mice. Splenocyte proliferation at suboptimal mitogen doses is greater in transgenic than in control littermate mice, but neither IL‐2 synthesis nor antibody synthesis to sheep erythrocytes is affected. The role of pituitary hormones on progenitor T‐cells was then explored by implanting GH3 cells into Rowett nude rats. GH3 cells are unable to augment proliferation to T‐cell lectins, IL‐2 synthesis, antibody production to sheep erythrocytes, or NK activity in nude rats. Collectively, these experiments show that T‐cells and NK cells from aged rats are not inherently defective because their proliferative responses to lectins and cytolytic activity can be augmented by exogenous GH. If GH affects progenitor T‐cells, these effects are not apparent in nude rats. Finally, GH can also augment T‐cell proliferative responses in young rodents, but the immunoenhancing effects are not as apparent as thos observed in immunocompromised aged animals.
The influence of nerve growth factor on the in vitro proliferative response of rat spleen lymphocytes
Authors: Thorpe L. W. , Perez‐Polo J. R. 
Published: January 2005

AbstractSplenic lymphocytes and accessory cells express receptors for nerve growth factor (NGF), a well‐characterized neurotropic peptide that influences the development and survival of neuronal elements in the central and peripheral nervous systems. In the present study, we report that when rat splenic mononuclear cells (MC) are incubated in the presence of NGF, a dose‐dependent increase in DNA synthesis occurs during 96–120 hours of culture as measured by 3H thymidine (3H‐Thd) uptake. The minimal molar concentration of NGF at which the increased proliferative response of the cells (3.7 nM) is seen corresponded to the equilibrium disassociation binding constant of the MC (Kd = 2.5 nM), suggesting that the response was a consequence of receptor‐ligand interaction. In addition, NGF was able to potentiate the lymphoproliferative response to several T‐cell and B‐cell mitogens. Significantly increased 3H‐Thd uptake by NGF‐stimulated cells was noted for concanavalin A (Con A), phytohemagglutinin (PHA), and lipopolysaccharide (LPS), particularly at suboptimal dosages of mitogen. Thus it appears that the NGF receptors on rat splenic MC are physiologically relevant and that NGF can modulate proliferation of T‐ and B‐ cells.
Central action of interleukin‐1 in altering the release of tsh, growth hormone, and prolactin in the male rat
Authors: Rettori V. , Jurcovicova J. , McCann S. M. 
Published: January 2005

AbstractIn order to determine the possible effects of interleukin‐1 on the release of pituitary hormones by direct action on the brian, the peptide was injected into the third brain ventricle of conscious, unrestrained male rats and the effects on hormone release were compared with effects on rectal temperature. The procedure of blood sampling and intraventricular injection resulted in a significant decline in body temperature and a decrease in plasma growth hormone without alteration in the plasma level of thyroid stimulating hormone (TSH) and prolactin. Interleukin‐1 injected intraventricularly at a dose of 5 ng (0.3 pmol) prevented the decline in body temperature that occurred in the saline‐injected controls and resulted in a significant elevation of plasma growth hormone levels that became apparent within 15 min of injection, as well as a highly variable but significant elevation of plasma prolactin and a significant decline in plasma TSH that was observed at 30 min. The results were similar when areas under the release curves for the various hormones were calculated. On the other hand, the higher dose of 25 ng (1.5 pmole) of interleukin‐1, although producing a frank pyrexia, was associated with smaller changes in hormone values, which were no longer significant for any of the three hormones. The results indicate that interleukin‐1 can act in minute doses, presumably on structures near the third ventricle, to stimulate growth homone and prolactin release and to inhibit TSH releas. Apparently when frank febrile responses occur, these hormonal responses are muted for reasons that are yet to be determined. In view of the minute doses injected we favor a hypothalamic site for these effects.
Synthetic peptide analogs to probe the immunological expression of the rat encephalitogenic neuropeptide
Authors: Hashim G. A. , Day E. D. 
Published: January 2005

AbstractThe rationale for designing and synthesizing 24 different peptide analogs and subpepties of residues 69–84 of guinea pig myelin basic protein is presented. The encephalitogenic potential of 19 of these peptides in Lewis rats is also given.
Glial glutamate dehydrogenase: Ultrastructural localization and regional distribution in relation to the mitochondrial enzyme, cytochrome oxidase
Authors: Aoki C. , Milner T. A. , Berger S. B. , Sheu K.‐F. R. , Blass J. P. , Pickel V. M. 
Published: January 2005

AbstractGlutamate dehydrogenase (GDH) is primarily a mitochondrial enzyme involved in the metabolism of glutamate. We have recently shown by light microscopic immunocytochemistry that, within detergent‐permeabilized brain tissue, GDH is enriched in glial cells, particularly in regions utilizing L‐glutamate as a neurotransmitter. In this study, we used immunogold labeling to quantitatively establish that the forms of the enzyme recognized by the presently used GDH antiserum is associated primarily with a subpopulation of mitochondria in ultrathin, plastic‐embedded sections of the rat cortex and striatum. Permeabilization with detergents was omitted in these studies, so as to preserve the ultrastructure. As expected, labeled mitochondria occurred both in neurons and glia. Furthermore, light microscopic comparisons of the regional distributions of peroxidase immunoreactivity for GDH and a histochemical reaction product for a second mitochondrial enzyme, cytochrome oxidase (CO), were used to demonstrate that high levels of GDH in glia of glutamate‐receptive areas do not necessarily reflect the areas's demand for elevated oxidative metabolism. While all showing intense labeling for glial GDH also exhibited high levels of CO activity, many additional regions showing high levels of CO activity contained no detectable immunoreactivity for glial GDH. These light‐microscopic comparisons reveal that the energy requirments are not the only factors accounting for the regional heterogeneity of the enzyme. We conclude that glial mitochondria are heterogeneous withe respect to their GDH content and that GDH is enriched in areas exhibiting chronically active glutamatergic transmission.
Synthesis of leukotrienes in frog retina and retinal pigment epithelium
Authors: Bazan N. G. , Bazan H. E. P. , Birkle D. L. , Rossowska M. 
Published: January 2005

AbstractLeukotrienes (LT) were identified in the intact frog (Rana pipiens) retinalpigment epithelium (RPE), retina, isolated rod outersegments (ROS), and ROS‐free (neuronal) retina. Levels of endogenous LTC4 were measured by radioimmunoassay (RIA) in both unpurified by reverse‐phase high‐performance liquid chromatography (HPLC). The purified LTC4 exhibited characteristic ultraviolet absorption spectrum with λmax at 280 nm. The Ca2+ ionophore A23187 (10 μM) increased LTC4 production in intact and ROS‐free retina and RPE but had no effect on LTC4 levels in isolated ROS. This lack of effect suggests that LTC4 is present but notsynthesized in ROS. Synthesis of radiolabeled LTC4 in frog retina and RPE prelabeled in vivo by intravitreal injection of [1‐14C]arachidonic acid (20:4, n‐6) provided an additional verification of the presence of LTC4 in these tissues. The physiological significance of the presence of these biologically active derivatives of arachidonic acid in photoreceptorcells and retinal pigment epitelium may be related to the interactions between these cells, consisting of photoreceptor membrane shedding and phagocytosis.
Chronic nicotine administration incrreases binding of [3H]Domperidone in rat nucleus accumbens
Authors: Reilly M. A. , Lapin E. P. , Maker H. S. , Lajtha A. 
Published: January 2005

AbstractAn apparent inverse relationship between smoking and Parkinson's disease prompted and investigation of the effect of chronic nicotine administration on dopaminergic and serotonergic receptors in rat brain. Nicotine, 0.8 mg/kg, was injected once daily, five times per week, for 6 weeks. In nucleus accumbens the Kd for [3H]domperidone was increased 2–4‐fold, and the Bmax was increased 1.5–2‐fold. No changes were observed in the binding of [3H]domperidone in caudateputamen or in that of [3H]ketanserin in frontal cortex. It is concluded that chronic nicotine administration may have a suppressant effect on central nervous system release of dopamine that in pre‐parkinsonian persons causes an aversion to the effects of smoking.
Dopamine and serotonin inhibition of neurite elongation of different identified neurons
Authors: McCobb D. P. , Haydon P. G. , Kater S. B. 
Published: January 2005

AbstractThis study demonstrates that a second classical neurotransmitter, dopamine, can act to suppress regenerative neurite outgrowth. Single identified neurons were dissected from two central ganglia of the snail Helisoma, and growth cone motility was studied as neurites regenerated in cell culture. Both dopamine and serotonin inhibited growth cone motility and elongation of neurites. Outgrowth inhibition ranged from sustained arrest to a similar but transient response. The effects of dopamine and serotonin are neuron‐selective. Specific neurons affected by dopamine and serotonin represent distinct sets. One neuron was found that response to both agents. The implications of neurotransmitter regulation of the dynamics of neuronal morphology are discussed.
Developmental effect of dimethyl sulfoxide on hypothalamo‐neurohypophysial neurons in vitro
Authors: Schilling K. L. , Pilgrim C. 
Published: January 2005

AbstractPrimary dissociated cultures were established from diencephalic tissue of 14‐day‐old fetal rats. Neurons exhibiting immunocytochemical staining for neurophsin appeared in these cultures after 6 days of cultivation. Addition of dimethyl sulfoxide (DMSO) to the culture medium resulted in a slight decrease in total neuronal cell mass as assessed by immunocytochemistry and radio‐immunometric quantitation of neuron‐specific enolase. In contrast, in DMSO‐treated cultures the number of neurophysin‐immunoreactive neurons was more than doubled as compared to control cultures. [3H] Thymidine labeling and autoradiography in conjuction with immunocytochemistry for neurophysin showed that this was not due to a mitogenic effect of DMSO on precursor cells. Time‐course analysis of the action of DMSO revealed a 6‐day time lag between the initiation of treatment and the appearance of increased numbers of neurophysin‐immunoreactive cells. These findings suggest that DMSO, which has previously been on malignant transformed cells, may also modulate cellular processes that control differentiation in specific types of neurons in primary culture.
Phorbol ester enhances morphological differentiation of oligodendrocytes in culture
Authors: Yong V. W. , Sekiguchi S. , Kim M. W. , Kim S. U. 
Published: January 2005

AbstractThe effects of phorbol esters have been attributed to the activation of the enzyme protein kinase C. While much has been described for the actions of phorbol esters on neurons and synaptic transmission, sparse data exist on the effects of phorbol esters on oligodendrocytes, the cells that make and maintain myelin in the central nervous system. In this report, we show that 10 and 100 nM of a phorbol ester, 4β–phorbol–12, 13–dibutyrate, extensively enhanced process formation by cultured bovine oligodendrocytes. This effect was blocked by two inhibitors of protein kinase C, sodium heparin and polymixin B. We propose the hypothesis that activation of protein kinase C is an important process that leads to the differentiation of oligodendrocytes and the formation of myelin in vivo.
A chemically defined medium for the culture of mature oligodendrocytes
Authors: De Los Monteros A. Espinosa , Roussel G. , Neskovic N. M. , Nussbaum J. L. 
Published: January 2005

AbstractA new chemically defined medium consisting of equal parts of Dulbecco modified Eagle's and Ham's F‐12 media supplemented with insulin, sodium selenite, putrescine, and D+ galactose, which allows the longterm survival of mature oligodendrocyte pure cultures, is described. Immunohistochemical staining has shown that over 90% of the cells become positive for myelin proteins shortly following subculture. Contaminating astrocytes (2%) do not survive in this medium. Biochemical data have indicated that these purified oligodendrocytes express 2′ 3′‐cyclic nucleotide 3′‐phosphohydrolase and UDP‐galactose ceramide galactosyltransferase activities. Electoron microscopical examination revealed that the oligodendrocytes were mostly of medium‐dark type and appeared to be identical to cells cultured in serum‐containing medium. The ability to maintain pure oligodendrocyte cultures in such a defined medium will allow investigations concerning exogenous and endogenous factors involved in oligodendrocyte metabolism.
Effect of laminin and cytoskeletal agents on neurite formation by NG108‐15 cells
Authors: Kleinman H. K. , Luckenbill‐Edds L. 
Published: January 2005

AbstractLaminin promotes attachment and process formation in the neuroblastoma x glioma hybrid cell line NG108–15. As cells attached to laminin, they flattened and remained dispersed rather than associated in clumps. Process formation was observed within 1 hr after exposure to laminin and was dose dependent. Cycloheximide, an inhibitor of protein synthesis, did not block laminin‐mediated attachment and neurite formation. Addition of drugs that depolymerize the cytoskeleton led to different behaviors for cells grown on plastic compared with those in the presence of laminin. Cells on plastic treated with either vinblastine or cytochalasin neither flattened nor grew processes. Cells plus laminin and vinblastine retracted processes, but remained flat, suggesting that laminin‐induced processes can be destabilized by disrupting microtubules. Cells sequentially treated with laminin and cytochalasin produced processes that were thin and highly branched. Cells in high concentrations of cytochalasin on a laminin substrate formed aberrant processes even when their soma did not flatten. Since laminin counteracted the effect of cytochalasin on process outgrowth but did not alter the effect of cytochalasin on flattening of the cell body, different mechanisms mediated by microfilaments may be involved in cell flattening and in process formation.
Angiotensinogen gene expression in neuronal and glial cells in primary cultures of rat brain
Authors: Kumar A. , Rassoli A. , Raizada M. K. 
Published: January 2005

AbstractNeuronal and glial cells in primary culture prepared from the hypothalamic‐brain stem areas of one‐day‐old rat brain were analyzed for the presence of angiotensinogen messenger RNA (mRNA) to further confirm our previous conclusion that the brain contains an exclusive angiotensin system. Angiotensinogen mRNA was quantitated by Northern analysis using nick‐translated angiotensinogen cDNA as the hybirdization probe (Kunapuli and Kumar, 1987). Angiotensinogen mRNA sequences were present in the RNA isolated from both neuronal and glial cultures. Quantitative measurements of the mRNA using dot‐blot analysis revealed that the level of angiotensinogen mRNA was three times higher in neuronal cultures compared with glial cultures. These observations provide the first evidence for the synthesis of angiotensinogen in neuronal as well as in glial cells form the brain.