bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early appearance of tyrosine hydroxylase immunoreactive cells in the mesencephalon of mouse embryos
Authors: Di Porzio Umberto , Zuddas Alessandro , Cosenza‐Murphy Dano B. , Barker Jeffery L. 
Published: April 2003

AbstractThe development of mesencephalic catecholaminergic neurons in the embryonic and fetal mouse was analysed in tissues fixed with 5% acrolein using polyclonal rabbit antibodies against tyrosine hydroxylase (TH), the first enzyme in catecholamine synthesis. The first TH positive cells were identified as early as day 8.5–9 of gestation and some expressed TH while apparently still migrating from the proliferative layer. The number of catecholamine cells increased dramatically by embryonic day 9.5–10; at gestation days 10.5–11 numerous TH positive cells bearing many neurites were localized in the ventral part of the mesencephalon but they were not yet separated into two different groups (A9 and A10). After 13 days of gestation two separate catecholaminergic groups could be visualized, although many TH positive cells with long neurites (putative dopaminergic neurons) could still be seen at the edges of the ventricle, and appeared to be moving towards the ventral mesencephalon.On the basis of these results the possibility that catecholamine cells that are produced early during the development of the midbrain may have neurotrophic and/or morphogenetic roles is discussed.
Immunocytochemical detection of glutamate decarboxylase in the postnatal developing rat organ of corti
Authors: Merchan‐Perez Angel , Gil‐Loyzaga Pablo , Eybalin Michel 
Published: April 2003

AbstractUsing a fluorescent avidin‐biotin technique, we have immunolocalized the GABA synthesizing enzyme, glutamate decarboxylase, in postnatal developing and adult rat organs of Corti. At birth, the glutamate decarboxylase‐like immunoreactivity is already present in the basal turn below the inner hair cells, i.e. within lateral olivocochlear efferent fibers of the inner spiral bundle. In the apical turn, the inner spiral bundle displays an immunoreactivity as early as postnatal day 3. Only the outer hair cells of the upper second turn and apex receive fibers immunostained for glutamate decarboxylase that most probably belong to the medial olivocochlear efferent innervation. They first appear at this level at postnatal day 15. Within these two regions of the organ of Corti, the glutamate decarboxylase‐like immunoreactivity reaches an adult‐like pattern at postnatal days 17–18. These results strengthen the hypothesis that GABA is a putative neurotransmitter that could be used by subpopulations of the two olivocochlear innervations. They also suggest that GABA either plays a neurotrophic function or participates in the regulation of the first cochlear potentials at the level of lateral efferent synapses.
Sprouting by isolated Helisoma neurons: Enhancement by glutamate
Authors: Bulloch A. G. M. , Hauser G. C. 
Published: April 2003

AbstractWe tested glutamate for its ability to modulate neurite outgrowth from isolated neurons of the adult snail, Helisoma trivolvis. Although glutamate did not induce neunte outgrowth from neurons maintained in defined medium, nevertheless it showed a dose‐dependent ability to enhance the activity of conditioned medium. We concluded that glutamate can enhance the release and/or activity of CNS derived sprouting factor(s) present in conditioned medium.The general conclusion to be drawn from this study is that the ability of a neurotrophic factor(s) to promote neunte outgrowth can be regulated by a neurotransmitter. This mechanism may be important in the regulation of trophic factors in the adult nervous system.
GABA agonist induced changes in ultrastructure and GABA receptor expression in cerebellar granule cells is linked to hyperpolarization of the neurons
Authors: Belhage Bo , Hansen Gert H. , Schousboe Arne 
Published: April 2003

AbstractGABA has been shown to exert a neurotrophic like activity by enhancing the morphological and functional maturation of neurons. Mechanisms involved in this effect of GABA are largely unknown but since GABA has been shown to mediate a hyperpolarizing action on neurons it can be assumed that this action might be important. In order to investigate this possibility, the ability to mimic the trophic actions of GABA of different agents known to influence the membrane potential or the GABA gated chloride channels was studied. Hence, GABA receptor expression as well as the ultrastructure of cerebellar granule cells were monitored after exposure of the cells in culture to either bromide, valinomycin or picrotoxin. It was found that cells which at early developmental stages (4 days in culture) were exposed to bromide or valinomycin expressed low affinity GABA receptors similar to cells treated with the GABA agonist 4,5,6,7‐tetrahydroisoxazolo[5,4‐c]pyridin‐3‐ol (THIP). This was in contrast to untreated cultures or cultures treated with both THIP and picrotoxin which expressed only high affinity GABA receptors and no low affinity receptors. In cultures at more mature stages (14 days in culture) bromide treatment did not lead to formation of low affinity GABA receptors. Studies of the ultrastructure of the cells (4‐day‐old cultures) showed that exposure to bromide or valinomycin mimicked the ability of THIP to enhance the cytoplasmic density of rough endoplasmic reticulum, Golgi apparatus, vesicles and coated vesicles. Again, in 14‐day‐old cultures treatment with bromide had no effect on the ultrastructure. Exposure of the cells to picrotoxin significantly reduced the ability of THIP to induce the increase in the density of the organelles mentioned above. Altogether the results strongly suggest that the hyper‐polarizing action of GABA via the chloride channels coupled to high affinity GABA receptors is the permissive signal for initiation of further reactions involved in the trophic and differentiating actions of GABA.
Antioxidant effect of retinoic acid on PC12 rat pheochromocytoma
Authors: Jackson George R. , Morgan Brent C. , Werrbach‐Perez Karin , Perez‐Polo J. Regino 
Published: April 2003

AbstractRetinoic acid is a naturally occurring metabolite of vitamin A that influences the differentiation of a variety of neural cells in vitro. In the LA‐N‐1 human neuroblastoma line, retinoic acid treatment increases the binding of nerve growth factor (Bmax). The purpose of this study was to examine the effects of retinoic acid on PC12 rat pheochromocytoma, a neural crest‐derived cell line that can be induced to express a sympathetic neuroblast‐like phenotype by nerve growth factor treatment. In contrast to the differentiating effects of nerve growth factor, retinoic acid treatment of PC12 cells had a negligible effect on cellular morphology. However, treatment with retinoic acid enhanced the survival of PC12 cells following oxidative injury generated by H2O2 treatment in a manner that is qualitatively similar to that observed after nerve growth factor treatment. Also, there was an increase in 125I‐nerve growth factor binding activity in solubilized PC12 membrane preparations derived from retinoic acid‐treated PC12 cells. These data suggest that retinoic acid may play a role in neuronal development and in neuronal injury by stimulating the ability of neurons to cope with oxidative stress and/or by enhancing neuronal responsiveness to trophic factors such as the nerve growth factor.
Development of binding sites for excitatory amino acids in cultured cerebral cortex neurons
Authors: Wahl P. , Honoré T. , Drejer J. , Schousboe A. 
Published: April 2003

AbstractBinding of [3H]glutamate, [3H]AMPA (RS‐α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolo‐propionate) and [3H]kainate was investigated in membranes prepared from cerebral cortex of 4‐day‐old and adult mice and from cerebral cortex neurons cultured for different periods of time (2, 4, 8 and 14 days). For all ligands, the number of binding sites increased as a function of development both in vivo and in culture. A significant number of binding sites for the ligands could be demonstrated on the cultured neurons already after 2 days in culture. Scatchard analysis of the binding data showed a single population of binding sites for glutamate (KD≈200 nM) and kainate (≈6 nM) regardless of the developmental stage in vivo or in culture. In case of [3H] AMPA binding two binding sites with KD values of ≈6 nM and 100–200 nM could be demonstrated both in vivo and in culture. Binding of [3H]glutamate to cultured neurons could be displaced by N‐methyl‐d‐aspartate (100 μM) and quisqualate (3 μM) in an additive manner but d,l‐4‐aminophosphonobutyrate (100 μM) had no effect. AMPA binding to cultured neurons was much more (40‐fold) sensitive than kainate binding to the newly developed AMPA selective antagonist NBQX (2,3‐dihydroxy‐6‐nitro‐7‐sulphamoyl‐benzo(F)quinoxaline) indicating that kainate and AMPA bind to independent binding sites. Monitoring membrane potentials in the cultured neurons using the lipophilic cation TPP+ (tetraphenylphosphonium) it was demonstrated that potassium (55 mM) as well as glutamate, AMPA and kainate (100 μM) could depolarize the neurons both at early (2 days) and late (9 days) developmental stages in culture. The demonstration of functionally active receptors for the 3 excitatory amino acids in both immature (2 days in culture) and mature (8–9 days in culture) neurons is discussed in the light of previous studies of the development as a function of the culture period of effects of excitatory amino acids in neurons. It is concluded that no simple correlation exists between expression of binding sites for the excitatory amino acids and their ability to induce cytotoxicity and neurotransmitter release.
Effects of prostaglandin E2 and cyclooxygenase inhibitors on clustering and level of nicotinic acetylcholine receptor in mouse myotubes co‐cultured with spinal cord explant
Authors: Kimura I. , Nakagawa M. , Kobayashi S. , Kimura M. 
Published: April 2003

AbstractThe clustering and level of nicotinic acetylcholine receptor (n‐AChR) in cultured mouse myotubes are negatively controlled by endogenous phospholipase A2 (PLA2) (Kimura et al., Int. J. Devl. Neurosci.5, 127–133, 1987). The effects of PLA2‐related metabolites, prostaglandins, leukotrienes and platelet‐activating factor (PAF) were investigated using fluorescein isothiocyanate‐α‐bungarotoxin. Peak and total fluorescence within a cluster were used as indices of clustering and level of n‐AChR, respectively. Prostaglandin E2 (PGE2, 1–10 μm) decreased both indices in a concentration‐dependent manner. Aspirin and indomethacin, cyclooxygenase inhibitors, increased the indices at 1.0 μM and 10–30 nM, and decreased them at higher concentrations of 10–30 μM and 0.1–1 μM, respectively. Prostaglandin F2α (PGF2α, 1–10 μM), nordihydroguaiaretic acid (30 μM), a lipoxygenase inhibitor, and PAF (10 μM) had no effect. These results suggest that the control of endogenous PLA2 on the clustering and level of n‐AChR is due to PGE2, but not to PGF2α, leukotrienes or PAF.
Differentiation of a stem cell line toward a neuronal phenotype
Authors: Cheun Jane E. , Yeh Hermes H. 
Published: April 2003

AbstractThis study examined the morphology and the development of inward currents in the course of differentiation of a stem cell toward a neuronal phenotype. Using the P19 embryonal cell line, whole‐cell current profiles of P19 cells before, during and after retinoic acid‐induced differentiation were matched with their morphology as well as with the expression of neuron‐specific enolase‐like immunoreactivity. Prior to and during the initial 48 hr of retinoic acid treatment, P19 cells either lacked detectable currents or expressed a voltage‐dependent outward potassium current, did not display neuron‐like morphology and did not express neuron‐specific enolase‐like immunoreactivity. Upon completion of retinoic acid treatment, the current profile of fully differentiated P19 cells was hallmarked by a large voltage‐dependent inward current which consisted of a sodium current and a smaller cobalt‐sensitive calcium component, in addition to the potassium current observed earlier. Such cells invariably emitted neuntes and displayed neuron‐specific enolase‐like immunoreactivity. Interestingly, coupling was prevalent among P19 cells in the undifferentiated state but was absent in the fully differentiated cultures. In studying cells undergoing neuronal differentiation, these results underscore the importance of taking into account both electrical properties and morphological considerations in determining the degree of differentiation.
Ontogeny of glycerol phosphate dehydrogenasepositive oligodendrocytes in rat brain. Impaired differentiation of oligodendrocytes in the myelin deficient mutant rat
Authors: Gordon Marcia N. , Kumar Shalini , de los Monteros Araceli Espinosa , de Vellis Jean 
Published: April 2003

AbstractThe ontogeny of oligodendrocytes in the myelin deficient (md) rat mutant and in control rats was explored immunohistochemically using an antiserum against the oligodendrocyte specific enzyme, glycerol phosphate dehydrogenase (GPDH), and the avidin‐biotin complex technique. In control rats, GPDH was demonstrated to be expressed relatively early in oligodendrocyte differentiation, prior to either myelin basic protein or proteolipid protein expression. With development, oligodendrocytes containing GPDH increased in number, apparent staining intensity, cell soma area and process elaboration. Fewer GPDH+oligodendrocytes were observed in the brain of mutant rats than in unaffected littermates at all developmental ages, and major developmental increases in oligodendrocyte density were delayed. The density of GPDH+oligodendrocytes was reduced by about 40% in both the corpus callosum and in the cingulate cortex of P22–25 md mutants compared with control rats. The oligodendrocyte cell soma area was not influenced by the md condition, and increased 2‐fold with development in rats of both genotypes. The area of coronal sections occupied by the corpus callosum increased about 2.5‐fold with development, and was 30% smaller in mutant rats late in their lifespan than in unaffected littermates. The reductions in oligodendrocyte density reported here are of insufficient magnitude to fully account for biochemically measured reductions in oligodendrocyte gene expression accompanying the md trait, indicating that gene expression per oligodendrocyte is also impaired. Cell counts in control rats also revealed that oligodendrocytes are overproduced during development. Cell density and the total number of corpus callosum GPDH+oligodendrocytes per section were maximal at P22–25 and then decreased to adult values. These results suggest that glial cells, like neurons, may be generated in excessive numbers, and some subsequently die, as a normal concomitant of development.
Effects of nerve growth factor and acetyl‐l‐carnitine arginyl amide on the human neuronal line HCN‐1A
Authors: Westlund K.N. , Lu Y. , Werrbach‐Perez K. , Hulsebosch C.E. , Morgan B. , Pizzo D.P. , Eisenberg H.M. , Perez‐Polo J.R. 
Published: April 2003

AbstractThe HCN‐1A clonal cell line, derived from the cortical tissue of a patient with unilateral megencephaly, was shown to differentiate into a mature neuronal‐like state in the presence of the nerve growth factor, dibutyryl cyclic adenosine, 3′,5′‐monophosphate and either 1‐isobutyl‐3‐methylxanthine or forskolin. Differentiation was assessed by measuring the percentage of cells that displayed branched, varicose processes that stained for synaptophysin. Treatment of cultures with a cocktail containing forskolin increased immunocytochemical staining for gamma aminobutyric (GABA), neurofilament protein and the nerve growth factor receptor species p75NGFR. Treatment with acetyl‐l‐carnitine alone had some effects on the cell morphology while acetyl‐l‐carnitine arginyl amide and nerve growth factor together increased the GABA content. Positive staining levels for the neurotransmitters gamma aminobutyric acid, glutamate, somatostatin, cholecystokinin and vasoactive intestinal polypeptide were measured quantitatively for HCN‐1A under basal conditions.
Brain filament proteins in primary cultures derived from chick embryos early in development
Authors: Dahl D. , Maggini L. , Gilad V.H. 
Published: April 2003

AbstractBrain filament expression and neurofilament post‐translational modifications (phosphorylations) were studied in primary cultures derived from whole 3–4 day chick embryos. After 2–3 days in culture, neurofilament‐positive cells formed neuronal aggregates connected by bundles of neurites in a distinctive pattern similar to that observed in cultures derived from embryonal rat brain and neonatal rat cerebellum. Aggregates and neuritic bundles were stained with several monoclonal antibodies reacting with phosphorylated neurofilament epitopes. With two monoclonal antibodies reacting with phosphorylated forms of the high molecular weight neurofilament subunit, staining was only observed after 8 and 10 days in vitro. There was a major difference between rat and chicken with respect to astrocyte differentiation in culture. In chicken, the flat cells surrounding the neuronal aggregates remained constantly GFAP‐negative throughout the whole experimental period (10 days). GFAP‐positive cells were first observed within the neuronal aggregates on day 8 in vitro.
Calcitonin gene‐related peptide immunoreactive nerve fibers in the developing salivary glands of the rat
Authors: Salo Antero , Törnwall Jyrki , Virta Erkki , Uusitalo Hannu 
Published: April 2003

AbstractThe appearance and distribution of calcitonin gene‐related peptide immunoreactive (CGRP‐IR) nerve fibers was studied by indirect immunofluorescence microscopy in the developing salivary glands of the rat at daily age intervals from the 15th day in utero (i.u.) until birth and subsequently on the 2nd, 5th, 7th, 16th, 30th postnatal (p.n.) days. The findings were compared to samples of adult rats. CGRP‐IR fibers appeared on day 20 i.u. both in parotid and submandibular glands. In submandibular glands, fibers were first seen surrounding the developing ductal branches, in the mesenchyme and also in association with developing ducts and blood vessels. In the parotid gland CGRP‐IR fibers first appeared around ductal branches and blood vessels on day 20 i.u. and on day 21 i.u. CGRP‐IR nerve fibers were found in the mesenchyme and around developing ducts. The density of CGRP‐IR fibers was highest between the 2nd and 16th postnatal days, after which the amount of CGRP immunoreactivity slowly decreased to the levels of adult glands. The increase in a number of CGRP‐IR nerve fibers especially around the ductal and vascular elements in the developing salivary glands indicates that they may play a role in the functional maturation of salivary glands.
Influence of tongue myoblasts on rat dissociated hypoglossal motoneurons in culture
Authors: Ternaux Jean‐Pierre , Portalier Paule 
Published: April 2003

AbstractHypoglossal motoneurons of 1–2 day‐old newborn rats were retrogradely labelled following an injection of fluorescent latex microspheres and carbocyanines. Motoneurons were identified among the cell population of the hypoglossal nuclei during the dissociation and culture procedures. DiI labelled motoneurons could be maintained in culture on poly‐l‐lysine coating and Dulbecco Minimum Essential Medium with Ham F12 complement, supplemented with additives and 3% fetal calf serum. Neuronal survival as well as extension of neurites, identified by their content in DiI or by the presence of choline acetyltransferase immunoreactivity, was increased in the presence of myoblastic satellite cells originating from tongue muscular expiants. Co‐cultures of dissociated hypoglossal cells with tongue myoblasts revealed the presence, after 10–15 days in culture, of structures morphologically similar to neuromuscular junctions. Such re‐innervated muscular fibres exhibited muscular contractions which were blocked by curare and augmented by glutamate applications, demonstrating the functionality of the observed re‐innervations.
Mesenteric neurons in the adult rat are responsive to ileal treatment with benzalkonium chloride
Authors: Cracco C. , Filogamo G. 
Published: April 2003

AbstractThe application of a 2 mM solution of the cationic surfactant benzalkonium chloride (BAC) to an ileal segment produced a selective and extensive myenteric denervation. The aim of the present study was to investigate whether such a selective unbalance of the enteric nervous system in the adult rat elicited any plastic response within the mesenteric nervous structures contacting it. Acetylcholinesterase (AChE) staining, β‐nicotinamide adenine dinucleotide (NADH) and β‐nicotinamide adenine dinucleotidephosphate (NADPH) diaphorase histochemistry and glyoxilic acid‐induced fluorescence were performed on whole‐mount preparations of myenteric plexus and mesenteric nerves. In both control and BAC‐treated animals nervous elements were detected along the mesenteric nerves. Although rather similar in position, shape and size, these neurons displayed striking differences with regard to their arrangement and density per nerve. In the controls, few small aggregates of neurons could be detected; more commonly, isolated nerve cell bodies were scattered along the nerve trunks. In the BAC‐treated animals, numerous spherical or spindle‐shaped clusters of neurons were located along the nerves; the mean neuronal density per nerve displayed a two‐five‐fold increase over the control values. The observed changes within the mesenteric nerves might be involved in an attempt at reinnervation of the BAC‐treated intestinal segments from extraenteric sources.
The migration of astrocytes after implantation to immature brains
Authors: Lund R.D. , Zhou H.‐F. , Yee K.T. 
Published: April 2003

AbstractUsing a species‐specific marker, we have found that astrocytes, taken from donors of varying ages from fetal to adult, migrate in highly Stereotypic patterns in immature host brains. Migration is primarily within and towards cell layers, although some cells are seen to migrate along fibre bundles. This contrasts with studies using the same approach in mature hosts, where migration is predominantly within fibre layers, largely excluding cellular regions.
Reactive astrocytes in explant cultures of goal scars derived from lesioned rat optic nerve: An ultrastructural study
Authors: Trimmer Patricia A. 
Published: April 2003

AbstractExplant cultures of glial scars generated by surgical removal of the retina in 3–60‐day‐old rats were used to determine if reactive astrocytes survive in vitro and how closely reactive astrocytes in culture resemble their in vivo counterparts. Characterization of the composition of age matched glial scars in vivo and in vitro showed that reactive astrocytes survived in glial scar explants even after several weeks in culture. Reactive astrocytes in both neonatal and adult glial scars retained ultrastructural features characteristic of reactive astrocytes in vivo. However, fewer reactive astrocytes survived in culture when explants were prepared from adult rat glial scars. The results of this study demonstrate that tissue culture is a viable model for the study of reactive astrocytes. A critical factor in the survival of reactive astrocytes in culture was the complete removal of myelin debris prior to the establishment of the culture. This outcome suggests that it will be important to clarify why myelin debris persists in culture and how it affects the survival of reactive astrocytes.