bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of β‐adrenoceptors in the syrian hamster harderian gland: Sexual differences and effects of either castration of superior cervical ganglionectomy
Authors: Pangerl A. , Pangerl B. , Buzzell G. R. , Jones D. J. , Reiter R. J. 
Published: January 2005

AbstractScatchard analysis of saturation isotherms of [125I]‐iodopindolol was used to characterize β‐adrenoceptor density (Bmax) and affinity constant (Kd) in female and male hamster Harderian glands. Single‐point experiments were also completed in intact females, intact males, and castrated or superior cervical ganglionectomized males. Scatchard analysis described a single population of binding sites with a Bmax of 292.2 ± 45.1 fmol/mg protein (X ± SEM, n = 6) in females and 18.2 ± 3.0 fmol/mg protein (n = 6, P < 0.001) in males. The affinity also varied significantly (P < 0.05) with a Kd of 1.08 ± 0.18 versus 0.26 + 0.05 nM (n = 6) in the Harderian gland of females and males, respectively. Single‐point [125I]‐IPIN (400 pM) binding values in females were 67.3 ± 4.0, in intact males were 12.8 ± 3.2, and in castrated males were 31.2 ± 4.2 fmol/mg protein (n = 7–9). Superior cervical ganglionectomy induced no significant changes in receptor binding. The results indicate pronounced sexual differences in the density and affinity of β‐adrenoceptors in the hamster Harderian gland, which may be sex hormone dependent.
Intracerebroventricular administration of bombesin inhibits biliary and gastric secretion in the rat
Authors: Yao C. Z. , Maclellan D. G. , Thompson J. C. 
Published: January 2005

AbstractThe effect of intracerebroventricular (ICV) bombesin on bile and gastric acid secretion was examined in the rat. ICV bombesin (10 μg in 10 μl) inhibited basal biliary volume by 27% and bile bicarbonate by 52% of control values, while gastric acid secretion was decreased by 75%. These results provide evidence for central mechanisms for the control of gastrointestinal function.
Na, K‐ATPase: Comparison of the cellular localization of α‐subunit mRNA and polypeptide in mouse cerebellum, retina, and kidney
Authors: Hieber V. , Siegel G. J. , Desmond T. , Lee‐Hwa Liu J. , Ernst S. A. 
Published: January 2005

AbstractA clone encoding mouse brain Na, K‐ATPase α‐subunit was isolated from a mouse brain lambda gt11 cDNA library by using antisera to mouse and bovine brain α‐subunit A comparison of the nucleotide sequence of this clone with published sequences of rat brain α‐subunit isoform clones showed it to be most similar to rat brain α1. An RNA antisense probe prepared from the cDNA insert of the mouse clone detected a single mRNA of approximately 4.5 kb in Northern blots of mouse brain and kidney RNAs. This probe hybridized only to an α1‐cDNA insert from rat brain under high stringency conditions on Northern blots. The RNA antisense probe was used for in situ hybridization to sections of mouse kidney, cerebellum, and retina, and the cellular distribution of α‐subunit mRNA (α‐mRNA) was compared with that of α‐subunit polypeptide (α‐subunit) detected by immunofluorescence in similar sections. In kidney, α‐mRNA distribution closely paralleled that of the polypeptide with abundant expression in ascending thick limbs and cortical distal tubules and weaker labeling in cortical proximal tubules. The co‐distribution of α‐mRNA and polypeptide in kidney where Na, K‐ATPase localization is well established is consistent with the specificity of these probes. In the retina, prominent labeling with both probes was seen in photoreceptor inner segments, inner nuclear layer, and ganglion cell bodies. Plexiform layers and optic fibers expressed abundant α‐subunit but little mRNA. Light labeling for both was seen in the outer nuclear layer. In cerebellum, α‐mRNA and α‐subunit were associated with soma of granule cells, basket cells, and stellate cells. Glomeruli and basket terminals contained abundant α‐subunit but exhibited little reactivity with the riboprobe. In Purkinje cell bodies, in contrast, the antibody used to identify the cDNA clone did not resolve significant polypeptide in the somal plasmalemma despite abundant somal mRNA expression. Comparison of distribution of the two probes in cerebellum and retina indicates that message accumulation is primarily in cell bodies, while α‐subunit epitopes may be co‐expressed in cell bodies and/or transported to distant sites in cell‐specific patterns.
Expression of pyruvate kinase in astrocytes induced to differentiate in vitro
Authors: Ngo J. L. , Ibsen K. H. 
Published: January 2005

AbstractAstrocytes maintained in a chemically defined media undergo differentiation and a parallel increase in pyruvate kinase specific activity. These changes are accompanied by a shift in the isoelectrofocusing pattern, but not by expression of pyruvate kinase M4 the characteristic adult rat brain isozyme. Thus, this chemically defined media lacks a substance required to induce pyruvate kinase M synthesis and this function can be uncoupled from other aspects of cellular differentiation. The uncoupling of pyruvate kinase maturation from cellular differentiation and the observation of only a single, 2.3 kilobase, pyruvate kinase mRNA molecule at different stages of the postnatal development of rat brain support the concept that the K‐ to M‐isoform transformation is a posttranscriptional event.The effect of the individual components of this chemically defined medium on pyruvate kinase specific activity was studied by eliminating one component at a time. The increase in activity was found to be completely dependent upon fibroblastic growth factor and prostaglandin F2α and was partially dependent on the simultaneous presence of insulin.
Development and regional expression of chicken neuroleukin (glucose‐6‐phosphate isomerase) messenger RNA
Authors: Hallböök F. , Persson H. , Barbany G. , Ebendal T. 
Published: January 2005

AbstractNeuroleukin (NLK) is a protein identical with the glycolytic enzyme glucos‐6‐phosphate isomerase (GPI) that has been reported to support the survival of a subpopulation of neurons in embryonic dorsal root ganglia and spinal cord neurons in culture.In this report we have studied the developmental expression of NLK mRNA in the chick embryo in order to evaluate its possible role as a neurotrophic factor. The chicken gene encoding NLK was isolated by cross‐hybridization to a mouse NLK cDNA clone. A DNA fragment from the chicken NLK gene with a 90% nucleotide sequence homology to mouse NLK cDNA encoding amino acids 310–355 was then used as a hybridization probe in a series of RNA‐blots. In the entire embryo NLK mRNA was found already at embryonic day 3.5 (E3.5) and the level of expression was significantly decreased between E3.5 and hatching. Roughly similar levels of NLK mRNA were found in all tissues of the E8 embryo analyzed, with the exception of the brain, which contained only low levels. When the developmental expression was analyzed in different tissues separately, NLK mRNA expression was found to decrease during development in the heart and bursa of Fabricius, whereas the level of mRNA in the brain showed a large increase shortly after hatching. The spinal cord and the pectoral and femoral muscles all showed high levels of NLK mRNA throughout development. In the adult chick, the highest levels of NLK mRNA were found in the muscle, brain, and kidney, where the NLK mRNA was estimated to account for approximately 0.1% of the total mRNA in these tissues. A widespread expression of NLK mRNA was observed in the adult brain with approximately similar levels in all brain regions tested. Similar results were also obtained when NLK mRNA expression was analyzed in adult rats. Our results show that developmental expression of the NLK gene is independently regulated in different tissues. The widespread and abundant expression of both the avian and rodent NLK gene is in accordance with its newly discovered identity as a glycolytic enzyme. Consequently, the developmental and adult pattern of NLK mRNA expression does not favour a specific trophic role for this protein in accordance with other known neurotrophic factors.
Effect of nerve growth factor on the elongation of neurites from axotomized rat embryonic septal‐basal forebrain neurons: An in vitro analysis
Authors: Schinstine M. , Cornbrooks C. J. 
Published: January 2005

AbstractThe administration of nerve growth factor (NGF) into the brain of a fornix‐fimbria lesioned rat can rescue many cholinergic, septal‐basal forebrain (SBF) neurons from imminent cell death. Unfortunately, it is nuclear if NGF can stimulate regenerative growth from axotomized, SBF neurons. In the present study, we used an in vitro model system to determine if NGF could affect neurite outgrowth from nonaxotomized and/or axotomized, embryonic SBF neurons. Axotomized neurons were obtained by severing the neuritic fields surrounding embryonic day (E) 15 SBF explants maintained in primary culture. Acetylcholinesterase (AChE) histochemistry was used to assess the effects of NGF on cholinergic neurites. We report that (1) neurite outgrowth on type I collagen from E15 SBF neurons in primary culture (nonaxotomized neurons) was not affected by NGF. (2) NGF enhanced the outgrowth (regeneration) of axotomized, SBF neurons on a collagen substratum; however, neurons had to be treated with NGF both before and after axotomy to stimulate regeneration effectively. Application of NGF either before or after axotomy did not enhance regenerative neurite outgrowth. (3) SBF neurons had to be axotomized for NGF to facilitate neurite outgrowth. This is supported by the observation that SBF explants, initially maintained in NGF‐supplemented medium in suspension culture, did not demonstrate enhanced neurite outgrowth in the presence of NGF when plated onto a substratum. (4) The regenerative growth of AChE‐negative, as well as AChE‐positive, neurites was facilitated by NGF treatment. In addition to data concerning neurite outgrowth, we also found that the NGF receptor, as recognized by the antibody 192‐IgG, expands its distribution as time in culture progresses; i.e., staining, originally confined to cell bodies and proximal processes within the explant, later included neurites that emanated from the explant. Thus, our results demonstrate that NGF can stimulate regenerative growth from axotomized, but not nonaxotomized, embryonic SBF neurons. We hypothesize that, given the appropriate substratum for axon elongation in vivo, NGF can stimulate the regeneration of SBF neurons in the injured adult brain.
Thiamine‐like molecules in the cerebellar cortex of the rat: Light and electron microscopic immunocytochemical investigation
Authors: Martínez‐Rodriguez R. , Díaz G. Arenas , Carnicero M. B. 
Published: January 2005

AbstractImmunocytochemical methods were used for studying the location of thiamine‐like molecules in the cerebellar cortex of the rat. A positive reaction was observed in several synapses and in several dendrites. This reaction was associated with tubular formations and synaptic vesicles. A positive reaction was also found in several mitochondria and in glial cells. The possible role of thiamine‐like molecules in cerebellar cortex is discussed.
Increase in cathepsin D activity in rat brain in aging
Authors: Kenessey A. , Banay‐Schwartz M. , de Guzman T. , Lajtha A. 
Published: January 2005

AbstractCathepsin D‐like activity in homogenates of five brain areas of 3‐month‐old and 24‐month‐old Fischer 344 rats was measured. With hemoglobin as substrate at pH 3.2, more than 90% of the activity was inhibited by pepstatin. In each area studied, activity was more than twice as high in the old rat brain: 140–160% higher in the cortex, cerebellum, pons‐medulla, and striatum and 90–100% higher in the hippocampus and spinal cord. The greatly increased metabolic capacity in the absence of an increase in protein turnover may have a role in age‐related pathological degeneration in the brain.
Acetyl‐L‐carnatine reduces the age‐dependent loss of glucocorticoid receptors in the rat hippocampus: An autoradiographic study
Authors: Patacchioli F. R. , Amenta F. , Ramacci M. T. , Taglialatela G. , Maccari S. , Angelucci L. 
Published: January 2005

AbstractBrain autoradiography in adrenalectomized rats injected with 3H‐corticosterone 2 hr before sacrifice was used to study the effect of aging and long‐term acetyl‐l‐carnitine treatment on the hippocampal glucocorticoid receptor.Densitometric analysis of silver grains in individual nerve cells of the hippocampus showed that pyramidal neurones of the CA1 field and granular cells of the dentate gyrus are richest in 3H‐corticosterone binding sites, whereas pyramidal neurons of the CA3 field have the lowest number of binding sites.There was a significant decline in the number of glucocorticoid receptors within the various hippocampal areas, both as the total number of 3H‐corticosterone binding sites and as the number per single pyramidal or granule neuron associated with aging and perhaps due to loss of adrenocorticoid‐competent neurons. The dentate gyrus and the CA1 region were mostly affected by the age‐dependent decrease in glucocorticoid receptors of the hippocampus.Twenty‐eight‐month‐old rats, treated with acetyl‐l‐carnitine for 7 months, showed a significantly higher number of 3H‐corticosterone binding sites within the various hippocampal regions examined than did age‐matched controls. The CA1 and the dentate gyrus were the regions most susceptible to amelioration by acetyl‐l‐carnitine treatment.These findings suggest a positive effect of acetyl‐l‐carnitine treatment on age‐related changes which occur in the hippocampus.
Role of the c‐myc and the N‐myc proto‐oncogenes in the immortalization of neural precursors
Authors: Bernard O. , Reid H. H. , Bartlett P. F. 
Published: January 2005

AbstractTo study the role of c‐myc and N‐myc in the immortalization of neural precursors, we infected neuroepithelial cells isolated from 10‐day‐old mouse embryos with a new retrovirus vector, pzen, harboring either the c‐myc or the N‐myc oncogene. The immortalized cell lines contain high levels of the virally expressed myc protein. The amount of myc proteins correlated with the capacity of the cells to differentiate spontaneously in vitro into neurons and glia; cell lines expressing high levels of myc protein can differentiate spontaneously while cell lines expressing low levels of the myc protein resemble epithelial cells. Addition of acidic or basic fibroblast growth factor enhanced differentiation of most cell lines. Some of the cell lines produced neurotrophic growth factors capable of supporting the growth of other cell lines at low density. There was no significant difference between cell lines immortalized with c‐myc or with N‐myc. Most of the immortalized cell lines generated from bipotential precursors are capable of differentiating into neurons and glia.
Magnocellular neurosecretory axon regeneration into rat intrahypothalamic optic nerve allografts
Authors: Dellmann H.‐D. , Lue L.‐F. , Bellin S. I. , Quassat M. 
Published: January 2005

AbstractTo test the working hypothesis that neurosecretory neuronal regeneration is largely dependent on microenvironmental conditions at the lesion site, intact or predegenerated optic nerves were allografted intrahypothalamically into the hypothalamo‐neurohypophysial tract. Neurosecretory axons regenerated consistently into all grafts. Early regeneration proceeded without glial cell association. At later stages of regeneration, however, neurosecretory axons were associated consistently with astrocytes that, within perivascular spaces, were surrounded by a basal lamina. Axons in contact with that basal lamina had the characteristics of terminals, suggesting functional recovery. It is postulated that it is the initial absence of a blood‐brain barrier at the graft site that provides a microenvironment similar to that in the neural lobe and that induces neurosecretory axon regeneration.
Phosphatidylinositol‐specific phospholipase C solubilized G2 acetylcholinesterase from plasma membranes of chromaffin cells
Authors: Prieto A. L. , Fuentes M. E. , Arqueros L. , Inestrosa N. C. 
Published: January 2005

AbstractUsing whole homogenates and defined subcellular fractions of bovine adrenal medulla, we investigated the properties of the dimeric G2 molecular form of acetylcholinesterase (AChE), its distribution, and the mode of attachment to chromaffin cells. Our studies indicate that a substantial fraction of the G2 form is specifically susceptible to solubilization by phosphatidylinositol‐specific phospholipase C (PIPLC) from subcellular fractions enriched with plasma membrane fragments. The results suggest that the G2 form of AChE is anchored in the plasma membrane to a glycolipid domain that contains phosphatidylinositol. Since a Ca+2‐dependent PIPLC has been previously described in chromaffin granules, it is possible that the adrenal AChE could be released by a system reminiscent of that involved in the case of the surface glycoprotein of Trypanosoma brucei.
Coated vesicles from developing and adult rat skeletal muscles contain multiple molecular forms of acetylcholinesterase
Authors: Hodges‐Savola C. A. , Gregory E. J. , Rummel S. A. , Fernandez H. L. 
Published: January 2005

AbstractThe main purpose of this work was to determine which of the multiple isoforms of acetylcholinesterase (AChE) are associated with clathrin‐coated vesicles (CVs) from developing and adult rat skeletal muscles. CV‐enriched preparations were obtained by subcellular fractionation/equilibrium sedimentation and further purified by immunoadsorption to anti‐clathrin IgG‐coated Staphylococcus aureus cells. Analysis of individual AChE isoforms by velocity sedimentation ultracentrifugation showed that (a) while both globular (G‐forms) and asymmetric (A‐forms) AChE were detected in all subcellular fractions evaluated, the CV‐enriched fraction contained a higher proportion of A‐forms (mainly the A12 species); (b) most of the AChE activity contained in such a CV fraction was recovered following immunoadsorption; (c) alkaline extraction conditions (pH 8.5) which depolymerize clathrin were necessary to detect a large proportion of A‐forms in both the CV‐enriched and immunoprecipitated preparations, while most of the G‐forms (especially G1 + G2 AChE) were detected following extraction at pH 6.8; and (d) comparison of AChE isoform profiles from neonate and adult muscle CV‐enriched fractions showed a greater concentration of A‐forms in the former. These data suggest that considerable amounts of A12 and, to a lesser extent, G4 AChE are sequestered within muscle CVs which may be destined for the plasmalemma. Our findings also indicate that the relative proportions of AChE isoenzymes in rat muscle CVs vary according to the extent of muscle development and lend support to the contention that CVs participate in the externalization of functionally important AChE isoenzymes.
Adenosine metabolism in neurons and astrocytes in primary cultures
Authors: Matz H. , Hertz L. 
Published: January 2005

AbstractMetabolic fate of [8‐14C]adenosine was studied in primary cultures of either astrocytes or neurons from the mouse brain. In astrocytes the main metabolic route was the formation of nucleotides. Thus, synthesis of adenosine triphosphate (ATP) amounted to about 0.2 nmol × min−1 × mg−1 protein. The deamination occurred less rapidly. The total rate of formation of inosine was difficult to establish because a considerable amount of labeled inosine accumulated in the medium. The initial incorporation of radioactivity into inosine in the medium was extremely rapid, probably because of the action of an ectoenzyme. However, the labeling of inosine in the medium also continued to increase slowly throughout the incubation, maybe as a result of release of intracellularly formed inosine. The total inosine formation rate during the incubation amounted to at most 0.1 nmol × min−1 × mg−1. Hypoxanthine was formed at a corresponding rate but was released to a lesser extent. In neurons much less label was incorporated into ATP. The major metabolite was inosine, formed intracellularly at a rate of 0.2 nmol × min−1 × mg−1. In addition, there was an immediate rapid labeling of inosine (and to a lesser extent hypoxanthine) in the medium, again suggesting the action of an ectoenzyme. Neither neurons nor astrocytes released a measurable amount of nucleotides to the medium.The cellular differences in adenosine metabolism are probably of relevance for the interpretation of adenosine metabolism in brain in situ. The ectoenzyme may be of importance for rapid termination of the neuromodulator activity of adenosine, and the rapid nucleotide formation in astrocytes is in agreement with a high metabolic activity of these cells.
Uptake and release of glycine in cerebellar granule cells and astrocytes in primary culture: Potassium‐stimulated release from granule cells is calcium‐dependent
Authors: Holopainen I. , Kontro P. 
Published: January 2005

AbstractThe properties of [3H]glycine uptake and release were studied with cerebellar granule cells, 7–9 days in vitro, (DIV) and astrocytes, 14–15 DIV, in primary cultures. The uptake of glycine in both cell types consisted of a saturable high‐affinity transport and nonsaturable diffusion. The transport constant (Km) and maximal velocity (V) were significantly higher in granule cells than in astrocytes. Uptake was strictly Na+‐dependent and also markedly diminished in low Cl medium. The specificity of the uptake was similar in both cell types. The spontaneous release of glycine from granule cells and astrocytes was fast. Homoexchange with extracellularly added glycine in granule cells suggests that the efflux is at least partly mediated via membrane transport sites in these cells. Kainate stimulated the release more effectively in neurons than in glial cells, the effect apparently being mediated by specific kainate‐sensitive receptors in both cell types. The release was enhanced by veratridine and by depolarization of cell membranes by high K (50 mM) in both neurons and astrocytes. The potassium‐stimulated release was partially Ca‐dependent in neurons but Ca‐independent in glial cells. The results suggest a functional role for glycine in both cerebellar astrocytes and glutamatergic granule cells.
EGF‐induced neuritogenesis and correlated synthesis of plasma membrane gangliosides in cultured embryonic chick CNS neurons
Authors: Rosenberg A. , Noble E. P. 
Published: January 2005

AbstractEpidermal growth factor (EGF), over a low range of concentrations (165–825 pM), induced neuritogenesis in post‐mitotic chick CNS precursor neurons cultured in a serum‐free medium, without the addition of other growth factors. Antibody to EGF blocks the neurite‐promoting activity of EGF. Similarl, neuritogenesis of cultured chick CNS neurons in medium supplemented with 20% fetal bovine serum is blocked by antibody to EGF, even though serum may contain other neuronotrophic bioactive proteins and steroids.Quantitatively, the only major gangliosides of the undifferentiated post‐mitotic neurons are GD3 and GD2.1 GD3 as well as its biosynthetic precursor, GM3, undergo active biosynthesis in serum‐free medium as evidenced by their vigorous labeling by radioactive galactose supplied in the culture medium. When the undifferentiated neurons in serum‐free medium are exposed to EGF, the ensuing generation of neurite plasma membrane coincides with initiation of biosyn thesis of the sialosyl gangliotetraosyl ceramide species of gangliosides (GD1A, GD1B, GT1B, GQ1B). Antibody to EGF simultaneously inhibits biosynthesis of these gangliosides as well as inhibition of neuritogenesis.These findings indicate that EGF may be a primary neurite‐inducing growth factor for post‐mitotic embryonic CNS neurons and that gangliosides, particularly those of the sialosyl gangliotetraosyl ceramide species, characterize the plasma membrane of CNS neurons during neuritogenesis.