bluuebunny/crossref_metadata_2025_split huggingface dataset:
GM1 ganglioside facilitates the recovery of high‐affinity choline uptake in the cerebral cortex of rats with a lesion of the nucleus basalis magnocellularis
Authors: Pedata F. , Giovannelli L. , Pepeu G. 
Published: January 2005

AbstractThe effect of repeated administrations of GM1 monosialoganglioside on high‐affinity choline uptake (HACU) was investigated in the cerebral cortex of rats with a unilateral electrolytic lesion of the nucleus basalis magnocellularis. In saline‐treated rats, 4 days after lesion, a 38% and 14% decrease in HACU‐activity was found in the ipsilateral frontal and parietal cortex, respectively. A spontaneous recovery of HACU activity occurred within the next 20 days. In rats receiving daily injections of GM1 from the day of operation, no significant decrease in HACU activity was found in the lesioned hemisphere 4 days after the lesion. In contrast a 25% increase in HACU activity in the frontal area of the opposite hemisphere was detected. No effect of GM1 treatment could be seen on days 10 or 20 after lesion. The possibility that GM1 may exert its stimulatory effect on HACU independently of the well‐known effect of gangliosides on neuronal sprouting is discussed.
Gangliosides minimize behavioral deficits and enhance structural repair after brain injury
Authors: Sabel B. A. , Dunbar G. L. , Stein D. G. 
Published: January 2005

AbstractInjections of GM1‐gangliosides (30 mg/kg, i. p.) in adult rats were shown to reduce behavioral deficits after brain lesions. This was observed (1) after bilateral electrolytic lesions of the caudate nucleus in a learning task involving negative reinforcement; (2) following aspiration lesions of the mediofrontal cortex in a learning task involving positive reinforcement; and (3) when rotational behavior was assessed after amphetamine or apomorphine injections in animals with partial hemitransections of the nigro‐striato‐nigral fibers. A detailed anatomical analysis of the latter study, using a retrograde tract‐tracing dye wheat germ agglutininhorseradish peroxidase (WGA‐HRP), provided evidence for ganglioside‐stimulated, neuronal reorganization of connections to the caudate nucleus.Our findings support the notion that gangliosides reduce behavioral deficits following brain injury by preventing secondary neuronal degeneration and/or enhancing structural reorganization of remaining afferents, rather than by influencing denervation supersensitivity.
Effects of GM1 ganglioside on developing and mature serotonin and noradrenaline neurons lesioned by selective neurotoxins
Authors: Jonsson G. , Gorio A. , Hallman H. , Janigro D. , Kojima H. , Luthman J. , Zanoni R. 
Published: January 2005

AbstractThe effect of exogenous GM1 ganglioside on selective neurotoxin‐induced lesions of serotonin (5‐HT) and noradrenaline (NA) neurons in both the central and peripheral nervous systems has been investigated in developing and adult rats and mice by employing neuro‐ and histochemical techniques. 5,7‐Dihydroxytryptamine (5,7‐HT) was used to lesion 5‐HT neurons, and 6‐hydroxydopamine (6‐OH‐DA) was used to lesion NA neurons. In most lesion models investigated the neurotoxin causes primarily an axonal nerve terminal damage without notably affecting the perikarya. There was no evidence indicating that GM1 interferes with the primary and direct neurodegenerative actions of 5,7‐HT or 6‐OH‐DA on 5‐HT and NA nerve terminals, respectively. In all lesion models GM1 had in the chronic stage a counteracting effect on the neurotoxin‐induced nerve terminal lesion or enhanced regrowth. The present results are compatible with the view that GM1 has a regrowth‐stimulating effect and/or protective actions against secondary retrograde degeneration following the initial nerve terminal lesion induced by the neurotoxin.
Gangliosides' dual mode of action: A Working hypothesis
Authors: Janigro D. , Di Gregorio F. , Vyskocil F. , Gorio A. 
Published: January 2005

AbstractUsing in vitro preparations, we have tested the hypothesis that gangliosides, and more specifically GM1, may prevent progressive neural damage following a trauma by means of complex intracellular mechanisms that might be triggered originally by ganglioside interaction with neuronal membranes. We have recently shown that 2‐hr ganglioside incubation in vitro stimulates the membrane Na/K pump in neuromuscular preparations. However, 5–6‐hr incubation or in vivo treatment for 3 days with a daily injection of gangliosides at a dose of 1 or 10 mg/kg prevents the depolarization that normally occurs after several hours of exposure to K+‐free solutions. In such undepolarized muscles, the electrogenic Na+/K+ pump does not seem to be activated.Hippocampal slices subjected to hypoxia undergo depolarization, which is reversed after oxygen readmission. The recovery phase is characterized by a huge hyperpolarization, probably reflecting electrogenic pump activity. In control preparations the depolarization occurs after 3.15 ± 0.4 min and has a value of 48.7 ± 5.7 mV; GM1 treatment for at least 4–5 hr increases the latency to 7.3 ± 2.3 min, and the depolarization is reduced to 31.8 ± 4.5 mV. This protective effect is accompanied by a reduced hyperpolarization in treated preparations. The ionic studies performed on neuromuscular preparations indicate that the protective effect may not be solely dependent on K+ leakage; however, the experiments are not conclusive and must be repeated with more direct methods.The results obtained indicate a dual mode of action for gangliosides. The early one seems characterized by membrane‐enzyme activation, perhaps in relationship to their incorporation in the membrane, which could be compatible with previously described effects, such as enhancement of neuronal sprouting and neuritogenesis. The late one, occurring 4–5 hr after ganglioside addition in vitro, might reflect intracellular events and be compatible with the protective action exhibited by gangliosides against neural damage.
β‐Adrenergic and muscarinic cholinergic receptors: Overlap in their genetic determination
Authors: Nagy A. , Reilly M. , Lajtha A. 
Published: January 2005

AbstractSignificant positive correlation between the ligand binding values for β‐adrenergic receptors and those for muscarinic cholinergic receptors was found in five inbred strains of mice (r = 0.84) and in different vertebrate species (r = 0.99).Comparative analysis of analogous receptor studies done on various brain regions in other laboratories revealed high positive correlation between regional binding values for these two receptors. In conjunction with the work presented here, an overlap in the genetic determination of β‐adrenergic and muscarinic cholinergic receptors is suggested.
Growth cone‐target interactions in the frog retinotectal pathway
Authors: Reh T.A. , Constantine‐Paton M. 
Published: January 2005

AbstractThe growth cones of retinal ganglion cell axons were studied in the optic tract and tectum with hoseradish peroxidase (HRP) histochemistry and electron microscopy. The ganglion cell growth cones has many morphological features similar to those described in vitro and in other in vivo systems. However, we found that some processes formed highly differentiated terminal arborizations, while retaining growth cones on many of their branches. In addition, ultrastructural examination of the tectal neuropil revealed that many ganglion cell axonal processes had characteristics of both growth cones and presynaptic endings. These findings are discussed in the context of the hypothesis of shifting connections and the evidence that retinotectal map formation involves several mechanisms, including a process that depends on the action potential activity in the optic fibers.
Cholinergic neurotransmission in the central nervous system of the snell dwarf mouse
Authors: Fuhrmann G. , Durkin T. , Thiriet G. , Kempf E. , Ebel A. 
Published: January 2005

AbstractAn unequal decrease in cholinergic activity has been evidenced in discrete brain areas in the growth hormone, thyroid‐stimulating hormone and prolactin deficient Snell dwarf mouse. The effect of the mutation's pituitary deficit on central cholinergic mechanisms appears to be selective: Normally high cholinergic activity areas such as striatum, olfactory tubercles, and hippocampus show strong alterations in this neurotransmitter system. Structures which appear earlier in ontogenesis are less affected, if at all. The lack of pituitary hormones seems to have effects on choline acetyltransferase activity and/or synthesis as well as on the development of high affinity (H. A.) cholinergic uptake mechanisms, both strongly defective in hippocampus and striatum. Therefore, a lower density of cholinergic terminals can be inferred. Furthermore, our observations are consistent with a close functional coupling of the choline H. A. transport and of subsequent choline acetylation. Acetylcholinesterase activity does not seem to be affected. Moreover, a compensatory effect at the postsynaptic level may have occurred due to developmental or functional plasticity for cholinergic responsiveness. In conclusion, the dwarf mouse seems to be a useful model for a better understanding of the influences of growth hormone and thyroid hormones on the development of central cholinergic mechanisms. It also provides the possibility to attempt a functional restoration of the deficient cholinergic neurotransmission and the behavioral disturbances which may be linked to them, by hormone replacement.
Modulation of anterior pituitary dopamine receptors by estradiol 17‐β: Dose‐response relationship
Authors: Ali S.F. , Peck E.J. 
Published: January 2005

AbstractExposure of ovariectomized rats to estradiol‐17‐β for 48–96 hr resulted in a dose‐dependent reduction in the number but not the Kd of D‐2 dopamine receptors of the anterior pituitary. No influence of estrogen was observed on dopamine or muscarinic acetylcholine receptors of caudate or hypothalamus. The dose‐response relationship observed suggested that the influence of estrogen is directly on the pituitary, not secondary to the alteration of dopaminergic systems in the hypothalamus.
False positiveness in a choline acetyltransferase assay caused by nonionic reducing reagents
Authors: Kobayashi Y. , de Vellis J. 
Published: January 2005

AbstractDithiothreitol and 2‐mercaptoethanol have been frequently used as protective agents of choline acetyltransferase (EC 2. 3. 1. 6) during its purification. We found that those reagents reacted with acetyl‐CoA to form products that were co‐extracted with acetylcholine into organic scintillation liquid to be erroneously detected as high enzyme activity. An anionic reducing reagent, such as sodium thioglycolate, does not cause the above problem and can be an alternative protective agent.
Nuclear uptake and retention of 3H‐dihydrotestosterone or one of its metabolites in the lower brainstem of the baboon
Authors: Sheridan P.J. , Weaker F.J. 
Published: January 2005

AbstractThe nuclear uptake and retention of androgen in the lower brainstem of the baboon was examined after the injection of 3H‐5α‐dihydrotestosterone. A specific topographical pattern of localization was observed in both motor systems and somatosensory systems. The pattern was similar to that reported in the rhesus monkey. The localization found in the primate differs from that of the rat in that the localization demonstrated in the rat is primarily restricted to motor systems.
Synthesis of myelin proteins and ultrastructural investigations in regenerating rat sciatic nerve
Authors: Alberghina M. , Bernocchi G. , Biggiogera M. , Viola M. , Karlsson J.O. , Manfredi‐Romanini M.G. , Giuffrida A.M. 
Published: January 2005

AbstractMyelin protein synthesis, as well as ultrastructural and morphometric changes in regenerating peripheral nerve, was studied. Sciatic nerves of rats were crushed unilaterally; sham‐operated nerves of the contralateral side served as controls. For the in vivo experiments, rats were killed at selected periods after the nerves were crushed (30, 60, 90, and 120 days); seven days prior to killing, the animals were injected intravenously with L‐[4, 5−3H]leucine. For the in vitro experiments, proximal and distal segments of sciatic nerve and equivalent sham‐operated nerves were labeled with 3H‐amino acid mixture 90 days after axotomy. Purified myelin was isolated from nerve segments; specific radioactivity and gel electrophoretic patterns of proteins were analyzed. Cross‐sectional electron microscope (EM) preparations of proximal, distal, and contralateral segments of nerves also were examined. Results showed that the incorporation of labeled amino acids into total myelin proteins was enhanced significantly in the distal segment of sciatic nerves at all of the periods of regeneration studied. The yield of myelin protein per mm distal nerve segment increased as regeneration proceeded. The remyelination of fibers early after nerve crush was weak, whereas it gradually attained the normal range 90–120 days after axotomy. Morphometric analysis of myelin sheath thickness of regenerating axons was consistent with the data obtained for myelin protein synthesis.
Developmental expression of 2′,3′ ‐cyclic nucleotide 3′ ‐phosphohydrolase in dissociated fetal rat brain cultures and rat brain
Authors: Bansal R. , Pfeiffer S. E. 
Published: January 2005

AbstractThe development in primary dissociated rat brain cultures of 2′,3′ ‐cyclic nucleotide 3′ ‐phosphohydrolase (CNP) activity, the accumulation of CNP protein, and the number of cells accumulating this protein have been quantitatively determined as a function of time in culture. Parallel determinations have been made for the first two parameters for developing rat brain. The developmental profile of CNP enzymatic activity of CNP protein in culture paralleled that observed in rat brain, in which the period of most active development occurred 7–25 days after birth. Mean CNP activities of 5.6 and 8.1 μmol/min/mg total protein were recorded for the cultures and rat brain, respectively, at their maximal levels. The corresponding mean values for the CNP protein accumulation were calculated to be 138 and 150 pmol/mg total protein, respectively. Thus maximal specific activities of the CNP protein were estimated to be about 800 and 1,100 μmol/min/mg CNP protein for culture and rat brain enzyme, respectively. Approximately three million cells expressing CNP appeared in the cultures per dissociated fetal rat brain seeded. Each CNP + oligodendrocyte in culture had an average CNP activity of 3.2 pmol/min, and an average CNP protein content of 0.09 gmol (5.4 × 107 molecules), values which remained nearly constant during the course of development. Two pricipal conclusions are drawn from these data. First, the dissociated fetal brain culture system reproduces rather accurately the temporal developmental pattern of CNP expression occurring in the rat brain, but some important quantitativ differences occur which suggest the need for additional environmental stimuli missing in these cultures. Second, the quantitative increases in CNP specific activity and amount of CNP protein occurring during oligodendrocyte differentiation in these cultures are primarily the result of increases in the number of CNP + cells present which upon differentiation express very quickly, via an off‐on regulation, steady‐state levels of the enzyme.
Effects of tunicamycin on NGF binding and neurite outgrowth in PC12 cells
Authors: Baribault T. J. , Neet Kenneth E. 
Published: January 2005

AbstractThe effects of inhibition of glycosylation on nerve growth factor (NGF) binding and neurite outgrowth response of PC12 cells have been examined. Exposure to tunicamycin (1–10 μg/ml) for 24–36 hr eliminates the rapidly dissociating component of NGF binding and decreases the decreases the proportion of PC12 cells capable of elaborating neurits in a dose‐dependent manner. These decreased cellular responses are probably due to an underglycosylation of the NGF receptor, since the effects of tunicamycin are correlated with a decrease in 3H‐fucose incorporation rather than a general decline in cellular metabolism as measured by viability and protein syntheses. These results suggest that carbohydrate side chains are important for the function and/or orientation of the NGF receptor in PC12 cells and that the rapidly dissociating component of NGF binding may be associated with a minimum concentration of functional receptors per cell required for the full biologic response.
Excitatory effect of amino acids on identified neuron R14 of Aplysia. II. Neutral amino acids and structure‐activity relationships
Authors: Ichinose Mitsuyuki , McAdoo D. J. 
Published: January 2005

AbstractThe effects of 20 amino acids on identified neuron R14 of Aplysia kurodai were studid by conventional intracellular recording and voltage‐clamp techniques. Neutral α‐amino acids caused marked dose‐dependent depolarizations of the neuron. The effects of several amino acids applied simultaneously were additive. L‐isomers were much more effective than the corresponding D‐isomers. R14 was at most slightly depolarized by perfusion with 2‐aminoisobutyric acid and the non‐α‐amino acids β‐alanine and β‐ and γ‐aminobutyric acid. Putative neurotransmitters ACh, 5‐HT, dopamine, GABA, and taurine were much less effective in depolarizing R14 than neutral amino acids. Values of the Hill coefficient (nH) and the apparent dissociation constant (KA) were approximately 0.64 and 80 mM, respectively, for glycine. These results suggest that R14 has a general sensitivity to neutral amino acids and that amino acids in the hemolymph may be able to influence the electrical activity of R14.
Regulation of myelination: Axons not required for the biosynthesis of basal levels of the major myelin glycoprotein by schwann cells in denervated distal segments of the adult cat sciatic nerve
Authors: Poduslo J. F. , Berg C. T. , Ross S. M. , Spencer P. S. 
Published: January 2005

AbstractThe adult cat sciatic nerve was examined for Schwann cell biosynthesis of the major myelin glycoprotein (P0) in the distal segments after permanent nerve transection, where there is no axonal regeneration or myelin assembly. Endoneurial slices (intrafascicular tissue) from the distal segment of the desheathed cat sciatic nerves at 10 wk after transection and from normal adult desheathed brachial nerves were incubated with radioactive mannose; [3H]mannose incorporation into P0 was observed by fluorography after sodium dodecyl sulphate‐pore gradient electrophoresis (SDS‐PGE). Analysis of immune precipitates by SDS‐PGE after incubation of an aliquot of an endoneurial fraction with rabbit antichick P0 gamma globulin verified that the [3H]mannose‐labeled glycoprotein was P0. The level of incorporation of [3H]mannose into P0 and into other endoneurial glycoproteins in the normal brachial nerve from the adult cat was at substantially reduced levels compared with the transected nerve. Such incorporation was detectable by fluorography only after prolonged exposure to X‐ray film (15 days). As a result, the level of biosynthesis of P0 in the normal adult cat is substantially reduced, suggesting that the extent of active myelination in the adult cat nerve is at a low level. Furthermore, Schwann cells are capable of continued synthesis of P0 in the adult, permanently transected nerve in the absence of axonal influence, suggesting that axonal association is not an absolute requirement for specifying myelin protein synthesis.
Phosphorylative neuromodulation of the regulatory subunit of cyclic AMP‐dependent protein kinase type II in skeletal muscle
Authors: McLane J. A. , Squinto S. P. , Yeoh H. C. , Held I. R. 
Published: January 2005

AbstractThe phosphorylative neuromodulation of the regulatory subunit of protein kinase type II (R‐II) in cytosolic fractions from denervated and sham‐operated, contralateral soleus muscles of the rat was evaluated. The denervation‐induced increase in the 32P‐phosphorylation of R‐II is not related to an increased dephosphorylation by cation‐dependent or cation‐independent protein phosphatases in the cytosolic fractions. The level of 32P‐phosphorylation of an exogenous heptapeptide substrate (Kemptide) by dissociated catalytic subunits of cyclic AMP‐dependent protein kinase in cytosolic fractions from denervated and sham‐operated solei did not differ. Also, no change in the concentration of cytosolic R‐II assessed by competitive enzyme‐linked immunosorbent assays (ELISA) was found after denervation. However, the in vitro 32P‐phosphorylation of R‐II in these samples was increased. Taken together, our results suggest that the increased availability of autophosphorylatable sites reflects an in vivo modulation of R‐II phosphorylation rather than a significant change in total R‐II content.
Altered respiratory response to substance P in capsaicin‐treated rats
Authors: Towle A. C. , Mueller R. A. , Breese G. R. , Lauder J. 
Published: January 2005

AbstractThe present investigation sought to examine the importance of substance P in the altered respiratory activity after neonatal capsaicin administration. Halothaneanesthetized adult rats given capsaicin neonatally exhibit a decreased basal minute ventilation with PaCO2 equal to and PaO2 greater than vehicle injected controls. In addition, the minute ventilation‐PaCO2 curve was displaced to the right. Acute bilateral cervical vagotomy severely blunted the minute ventilation response to PaCO2 and abolished the differences in ventilation between capsaicin treated and control rats. Neonatal capsaicin significantly reduced pons‐medulla substance P content but not TRH, serotonin or 5‐hydroxyindole acetic acid. Immunohistochemical studies revealed that substance P fibers of the trigeminal spinal nucleus were the most severely affected in the brain stem and that substance P fibers in the lung were totally absent.The intracerebroventricular administration of substance P increased minute ventilation similarly in both control and capsaicin treated rats, largely as a result of increases in tidal volume. The minute ventilation‐PaCO2 curve was similar in both groups after substance P administration. Simultaneous administration of the peptidase inhibitor captopril with substance P increased the respiratory response to substance P in normal rats. Administration of captopril to capsaicin treated rats restored the ventilation‐PaCO2 curve to the position observed in normal rats. The hypotensive response to intracerebroventricular captopril alone in control rats was less profound in rats given neonatal capsaicin.These results are consistent with the thesis that respiratory depression after capsaicin treatment is at least in part due to the loss of substance P primary afferent nerve terminals in the brain stem, suggesting that substance P fibers in the brain stem may participate in the normal modulation of respiratory activity.
Partial characterization of a brain extract factor(s) inhibitory to transformed neural cells
Authors: Schengrund C.‐L. , Repman M. A. 
Published: January 2005

AbstractThe factor(s) present in extracts prepared from the brains of newborn A/J or C57B1/6 mice, with inhibits S20Y neuroblastoma cell growth in vitro, was partially characterized. Twice as much ingibitory activity was extracted per gram wet weight of brain than torso, and inhibitor recovery was greatest in extracts prepared from brains of mice 1 week or less in age. The inhibitory factor(s) was water‐soluble and was stable to heating at 100°C, to freezing, and to lyophilization. It was susceptible to the action of pronase. The factor(s) behaved like a molecule of molecular weight ˜ 700 upon passage through ultrafiltration membranes. Growth of rat hepatoma (H4), murine melanoma (B16), and transformed murine fibroblasts (WT19 and B6‐HCMV) was not significantly inhibited by brain extract. Growth of rat glioma cells (C6) was significantly reduced but to a lesser degree than that of murine neuroblastoma cells (S20Y and N 115) and glioma cells (G26‐20). These results suggest that the inhibitor expresses a cell specificity.