bluuebunny/crossref_metadata_2025_split huggingface dataset:
Excitatory amino acid response in cultured rat striatal neurons results in a developmentally regulated cGMP formation
Authors: Novelli Antonello , di Porzio Umberto 
Published: April 2003

AbstractGlutamate and its analogues play a central role in excitatory neurotransmission throughout the brain. Their signal in the postsynaptic cells can be transduced by several second messengers. Here we show that in primary cultures of embryonic rat striatum, excitatory amino acid receptor stimulation increases cyclic GMP intracellular concentration and the magnitude of this response depends upon the time in culture. Formation of cyclic GMP appears to be mediated by both N‐methyl‐d‐aspartate (NMDA) and non‐NMDA type excitatory amino acid receptors, it is blocked by specific excitatory amino acid antagonists and requires extracellular Ca++. The effect mediated via the NMDA receptor is also regulated by extracellular Mg++.These results show that excitatory amino acids make use of cyclic GMP for signal transduction in striatal neurons in vitro. We suggest that cyclic GMP may be an independent second messenger possibly important in the development of a defined population of striatal neurons.
Visualization of taurine, GABA and glutamate in developing feline cerebellum by immunohistochemistry
Authors: Lu Peimin , Imaki Humi , Xu Weimin , Sturman John A. 
Published: April 2003

AbstractThe localization of taurine, GABA and glutamate in developing feline cerebellum was performed using antibodies raised against the amino acids conjugated to bovine serum albumin with glutaraldehyde. Distinct patterns of immunostaining were observed for each of the amino acids. Taurine‐like immunoreactivity reached a peak at 4 weeks after birth, as did GABA‐like immunoreactivity, whereas glutamate‐like immunoreactivity was greatest in the mature cerebellum. Purkinje cells are all taurine‐positive in cerebellum from neonatal animals, whereas in the mature cerebellum they appear to contain only GABA and glutamate, with virtually no taurine, in contrast to observations reported with rodent cerebellum. Ultrastructural studies and immunogold labelling visualized by electron microscopy show that the band of taurine‐like immunoreactivity observed in newborn feline cerebellum is localized within dendrites, axons and glial processes. Granule cells migrating through this region also show prominent taurine‐like immunoreactivity.
A developmental decrease in NMDA‐mediated spontaneous firing in cultured rat cerebral cortex
Authors: Ramakers G.J.A. , de Wit C. , Wolters P.S. , Corner M.A. 
Published: April 2003

AbstractIn primary cultures of fetal rat cerebral cortex chronic manipulation of the level and/or pattern of bioelectric activity leads to plastic changes in bioelectric activity, opposite to those seen during the manipulation. This suggests the presence of adaptive mechanisms which regulate functional development in the neuronal network. Since NMDA receptors play an important role in early postnatal bioelectric activity and have been implicated in activity‐dependent plasticity in vivo, the involvement of NMDA and non‐NMDA receptors in spontaneously occurring bioelectric activity was investigated in cultured rat cerebral cortex by assaying the effects of NMDA and non‐NMDA antagonists on neuronal firing. In addition, the physiological consequences of chronic suppression of bioelectric activity were investigated following development in the presence of tetrodotoxin. NMDA receptors appeared at all ages to be more crucial for spontaneous bioelectric activity than non‐NMDA receptors, although their relative importance decreased during the first 3 weeks. Whereas the NMDA antagonist APV strongly reduced burst firing, the non‐NMDA antagonist DNQX tended to increase burst firing slightly. Following chronic suppression of bioelectric activity, non‐variable burst firing was increased, thus replicating previous findings in cerebral cortex culture grown under different conditions. The prominence of NMDA receptor activation in spontaneous bioelectric activity in early cultures suggests a role for these receptors in activity‐dependent functional plasticity, as found in vivo.
Reactive astrocytes in neonate brain upregulate intermediate filament gene expression in response to axonal injury
Authors: Oblinger∗ Monica M. , Singh Leelabai D. 
Published: April 2003

AbstractWe have examined the injury response of astrocytes in the immature hamster brain in this study, focusing on alterations in the expression of glial fibrillary acidic protein (GFAP) and vimentin. In the adult CNS these two type III intermediate filament (IF) proteins have been shown to undergo robust increases in expression in response to axonal injury. Since injury to the immature CNS reportedly elicits less glial scar formation than adult brain injury, we examined the possibility that immature astrocytes respond differently than adult astrocytes to CNS injury with respect to IF gene expression. In situ hybridization using a 35S‐labeled cDNA GFAP probe was done on brainstem sections obtained 2,7 and 14 days after unilateral transection of the corticospinal tract in P8 hamster pups. The results indicated that substantial increases in GFAP mRNA were associated with the degenerating portion of the corticospinal tract by 2 days after axotomy and that the levels remained elevated for at least 14 days. Double‐label immunofluorescence studies of this material suggested that GFAP as well as vimentin protein levels were also increased in many astrocytes in and around the degenerating corticospinal tract 2–14 days after axotomy. Most of the reactive astocytes in the degenerating regions exhibited increases in GFAP and vimentin immunostaining but some vimentin‐negative GFAP‐positive reactive astrocytes were also observed, particularly in regions surrounding the actual degenerative zones. The results from these experiments revealed that immature astrocytes have the potential for altering their normal developmental program of GFAP and vimentin expression after injury and mount a response that is qualitatively similar to that of astrocytes after CNS injury in the adult animal.
Differential expression of immediate‐early proteins in non‐nerve cells after focal brain injury
Authors: Dragunow M. , Hughes P. 
Published: April 2003

AbstractWe investigated the expression of the immediate‐early proteins (IEPs, Fos, Fos B, Jun, Jun B, Jun D, Krox 20 and Krox 24) in non‐nerve cells in rat brain after mechanical brain injury. Injury produced by infusion of 5 μl of saline into the hippocampus produced a time‐dependent expression of Fos, Jun and Krox 24, but not Fos B, Krox 20 or in non‐nerve cells around the wound margin, in cells lining the lateral and third ventricles and in cells in the pial surfaces of the brain. Jun B and D were weakly induced in non‐nerve cells 1–4 hr after brain injury. This differential expression of IEPs in non‐nerve cells contrasted with neurons which expressed all IEPs measured. Thus, brain injury is associated with a differential expression of IEPs in non‐nerve cells around the wound. The functional implications of this IEP expression after brain injury are presently unclear, but may be related to cellular proliferation after brain injury.
Neuronal phenotypes in mouse dorsal root ganglion cell cultures: Enrichment of substance P and calbindin D‐28k expressing neurons in a defined medium
Authors: Ninomiya T. , Barakat‐Walter I. , Droz B. 
Published: April 2003

AbstractThe primary sensory neurons in mouse dorsal root ganglia consist of diversified subpopulations which express distinct phenotypic characteristics such as substance P or calbindin D‐28k. To determine whether neuronal phenotypes are altered or not in in vitro cultures carried out in a defined synthetic medium, dissociated dorsal root ganglion cells from newborn mice were grown in the alpha‐modified minimum essential medium either supplemented with 10% fetal calf serum or serum‐free. About 80% of the neurons survived after 5 days of culture in both media, but only 35% or 65% were rescued after 12 days in serum‐free or fetal calf serum supplemented medium, respectively. The neuronal subpopulations expressing substance P or calbindin D‐28k displayed similar morphological properties in both media and a higher resistance to culture conditions than the whole neuronal cell population, especially in serum‐free medium. It is therefore concluded that a defined synthetic medium offers reproducible conditions to culture dorsal root ganglion cells for at least 5 days, stimulates the expression of substance P and enriches preferentially neuronal phenotypes expressing substance P or calbindin D‐28k, for a longer period of culture.
Maturational changes in sympathetic and sensory innervation of the rat uterus: Effects of neonatal capsaicin treatment
Authors: Brauer M.M. , Lincoln J. , Sarner S. , Blundell D. , Milner P. , Passaro M. , Burnstock G. 
Published: April 2003

AbstractThe plasticity of the sympathetic and sensory innervation of the rat uterus was examined, before and after puberty, in controls and in animals where primary sensory nerves had been destroyed by neonatal capsaicin treatment. Immunohistochemical and histochemical methods were used in association with nerve density measurements and biochemical assays. The main findings were as follows: (1) Puberty was associated with a marked increase in the weight of the uterine horn, uterine cervix and parametrial tissue. This was unaffected by capsaicin treatment. (2) The sympathetic innervation of the uterine horn and parametrial tissue was reduced following puberty as revealed by a decrease in the density of noradrenaline‐containing nerves and a marked decrease in the tissue concentration of noradrenaline. Sympathetic nerves supplying the uterine cervix and the blood vessels of the uterus appeared to be unaffected by puberty. (3) In contrast, the sensory supply of the uterus by substance P and calcitonin gene‐related peptide‐containing nerves increased in parallel with uterine growth during puberty resulting in no change in nerve density and only a slight reduction in peptide concentration. (4) Neonatal capsaicin treatment caused a long‐lasting depletion of substance P‐ and calcitonin gene‐related peptide‐containing nerves. In the uterine horn and parametrial tissue, capsaicin‐resistant calcitonin gene‐related peptide, but not substance P, still increased with tissue weight during puberty, indeed, in the uterine horn, the relative increase was greater than in controls. (5) Sensory denervation resulted in an increase in the non‐vascular sympathetic supply of the uterus, although there was a regional variation in the time course of the response. Perivascular sympathetic nerves were unaffected by capsaicin treatment. The pattern of change in non‐vascular noradrenaline‐containing nerves associated with puberty was similar in nature to controls. Thus, there is considerable plasticity in the innervation of the uterus both during puberty and following sensory denervation. A complex pattern of change occurs with differential responses in vascular and nonvascular nerves and in different regions of the uterus. Such differences may be due in part to the different origins of individual nerve populations and/or to their relative sensitivities to sex hormones.
Gm1 ganglioside and darkly staining neurons in brains of rats subjected to neonatal hypoxia‐ischemia
Authors: Aguis Lawrence , Hadjiconstantinou Maria , Qu Zan‐Xi , Neff Norton H. , Pearl Dennis K. , Yates Allan J. 
Published: April 2003

AbstractRat pups, seven days old, with right carotid artery ligations were exposed to an atmosphere of oxygen 8% remainder nitrogen for 2 hr. The animals that survived for three weeks after the hypoxic‐ischemic episode had clusters of darkly stained (hematoxylin‐eosin) neurons in the cortex and reduced uptake of dopamine (frontal cortex) and choline (frontal cortex, hippocampus and striatum) in preparations of synaptosomes. Treatment with GM1 ganglioside partially corrected the loss of uptake activity and increased the number of darkly stained neurons.
Horizontal cells in the rabbit retina: Differentiation of subtypes at neonatal and postnatal stages
Authors: Lyser Katherine M. , Li Anne I. , Nuñez Maribel 
Published: April 2003

AbstractWe are investigating the differentiation of the major subtypes of horizontal cell in the rabbit retina in order to learn more about developmental controls responsible for the variety of neuronal phenotypes. Immunohistochemistry with anti‐neurofilament and anti‐calbindin‐D antibodies, followed by epoxy resin embedding, has facilitated study of these neurons. In the mature rabbit retina, axonless (A‐type) horizontal cells reacted strongly in procedures using either antibody; short axon (B‐type) somas did not show a reaction with anti‐neurofilament antibodies and stained moderately using anti‐calbindin antibodies. In the immature neonatal retina the somas of all the horizontal cells seemed to be similar with regard to general morphology, but two populations could be distinguished on the basis of immunostaining. Some, identified as A‐type horizontal cells (by comparison with mature retina), were stained using either antibody. Interspersed among these were similar cells with no detectable immunoreactivity, identified as B‐type horizontal cells. By the end of the first postnatal week, faint reactivity to anti‐calbindin‐D was present in the somas of B‐type horizontal cells; they stained moderately throughout the rest of the period studied.Thus differences in immunostaining indicate that the two horizontal cell subpopulations are established early in the rabbit, though some other distinguishing characteristics emerge only gradually as the retina matures. These results suggest that in mammals the determination of phenotypic subtype occurs early, possibly at the time that the cell is specified as a horizontal neuron, or shortly thereafter.
Persistence of heterotypical synapses in transplanted cerebellar cultures in the absence of functional glia
Authors: Seil Fredrick J. 
Published: April 2003

AbstractNeonatal mouse cerebellar cultures depleted of granule cells and functional glia by exposure to cytosine arabinoside were transplanted with either granule cells and glia or with granule cells in the absence of functional glia. Myelination was evident in cultures transplanted with granule cells and glia, excess sprouted cortical neurites were reduced, Purkinje cells acquired astrocytic sheaths and had a near normal complement of axosomatic synapses, and homotypical parallel fiber‐Purkinje cell dendritic spine synapses were present in a 2.4:1 ratio to heterotypical recurrent axon collateral‐Purkinje cell dendritic spine synapses. Cultures transplanted with granule cells were not myelinated, sprouted cortical neurites were not reduced, Purkinje cells lacked astrocytic sheaths and their somata remained hyperinnervated, and the ratio of homotypical to heterotypical dendritic spine synapses was 1.4:1. In the absence of functional glia there was a greater persistence of heterotypical recurrent axon collateral‐Purkinje cell dendritic spine synapses. These results are consistent with a previously described astrocytic role in the regulation of axosomatic synapse density on glially ensheathed neurons, and suggest astrocytic participation in the reduction of heterotypical axospinous synapses. Astrocyte‐mediated synapse reduction may be an important mechanism for circuit reorganization after transplantation or during development.
Acute effects of capsaicin on the postnatal spiral ganglion
Authors: Simmons D.D. , Rogers M.S. , Woody D. 
Published: April 2003

AbstractCapsaicin exerts both excitatory and desensitizing effects on a subset of sensory neurons during development in the dorsal root ganglion, but it is not known how widespread these effects are in other sensory ganglia especially those not known to have any pain sensitivity. The capsaicin sensitivity of auditory neurons in the spiral ganglion was investigated in acute preparations from three postnatal age groups in the hamster: postnatal days 6–8 (group 1), postnatal days 13–15 (group 2) and postnatal days 20–22 (group 3). Morphologically, capsaicin altered the shape, size, and staining characteristics of spiral ganglion cells (SGCs) across all age groups and this effect was apparently not selective for any identifiable subpopulation. However, SGCs from the youngest age groups were particularly sensitive to capsaicin neurotoxicity. When incubated in media that contained cobalt, capsaicin stimulated cobalt uptake within SGCs. KCl depolarization was able to produce the same level of cobalt uptake as capsaicin treatment. Our data suggest that the extent of capsaicin neurotoxicity in the spiral ganglion is strongly age dependent, involves the entry of calcium ions and is relatively nonspecific.
Changes in metabolic activity in the hyperstriatum of the chick before and after hatching
Authors: Rogers L.J. , Bell G.A. 
Published: April 2003

AbstractChanges in metabolic activity in the hyperstriatal regions of the chick forebrain have been assessed just prior to and after hatching using 14C 2‐deoxyglucose (2‐DG) autoradiography. Embryos were injected on day E19, followed by either exposure to light for 30 min or being held in darkness. Other embryos were injected on day E20, after pipping of the egg shell had occurred, and chicks were injected on day 1 (D1) after hatching, followed by light exposure. In the E19 groups metabolic activity in visual regions of the hyperstriatum accessorium (HA) was significantly higher than that in the hyperstriatum dorsale (HD), the region which receives the thalamofugal visual projections. The result was the same in both the light and dark exposed embryos, indicating that the high level of activity in HA on day E19 is not visually driven and that HA may be processing inputs from other sensory modalities. At stage E20 the activities of HA and HD did not differ and by day 1 post‐hatching HD activity exceeded that of HA. Activity in HA fell between E19 and E20, while in HD activity rose between E20 and D1. The developmental sequence of metabolic activity levels in the intermediate medial hyperstriatum ventrale (IMHV), a region involved with imprinting memory formation, was higher on E19 and D1 than on E20. E20 is thus a quiescent period of neural activity in the hyperstriatum prior to hatching. Although a small number of the embryos showed distinct hemispheric asymmetries in metabolic activity, overall there was no significant asymmetry in the embryo groups. The implications of these results for imprinting and early perceptual processing are discussed: it appears that HA activity may be inhibited or limited during the sensitive period for visual imprinting, thereby temporarily diminishing the importance of the thalamofugal visual pathway relative to the tectofugal pathway in the imprinting process.
Impaired neurogenesis by methylazoxymethanol in newborn rats results in transient reduction of ornithine decarboxylase and polyamines in the cerebellum, but not in the olfactory bulbs
Authors: Facchinetti F. , Ciani E. , Sparapani M. , Barnabei O. , Contestabile A. 
Published: April 2003

AbstractPolyamines and the key enzyme for their biosynthesis, ornithine decarboxylase (ODC) play an important role in the control of neuronal proliferation and differentiation. Exposure to agents that interfere with normal cell maturation is expected to result in alteration of neuronal ODC developmental pattern. We have administered to newborn rats, about 6 and 30 hr after birth, 20 mg/kg of methylazoxymethanol acetate (MAM), an agent able to selectively kill dividing cells and we have evaluated ODC activity and polyamine levels in the cerebellum and ODC activity in the olfactory bulbs at various developmental stages starting from postnatal day 4 (PD 4) until PD 28. Cerebellar weight decreased by 22–50% at the different developmental stages in MAM‐treated animals. A decline in ODC specific activity was observed at PD 4 and a decrease of putrescine levels at PD 4 and PD 6 in the cerebellum. At PD 10, however, both ODC activity and putrescine level were increased in MAM‐treated animals. Spermidine levels were never affected by the treatment, while spermine was significantly decreased at PD 6 and PD 8. These results demonstrate that altered ontogenetic patterns of ODC activity and polyamine levels are the consequence of disturbance of the normal process of brain maturation. No significant differences in specific ODC activity were noticed in the olfactory bulbs of MAM‐treated rats. This may be related to the more widespread time‐span of neurogenesis in this region, a fact that is also revealed by the higher ODC activity constitutively expressed at times in which neurogenesis has ended in the rest of the brain.
Thyroidal stimulation of tubulin and actin in rat brain cytoskeleton
Authors: De Arunangsu , Das Sumantra , Chaudhury Sukanya , Sarkar Pranab Kumar 
Published: April 2003

AbstractIn cultures of neonatal rat brain cells, labeled with 35S‐methionine in the presence or absence of triiodothyronine (T3), the hormone promoted a significant enhancement of labeled tubulin and actin in the insoluble fraction (30,000 g pellet) of cell homogenate. To identify the specific sub‐cellular fraction associated with this induction, organ cultures of 1 day rat cerebra were labelled with 35S‐methionine in the presence and absence of T3 and the insoluble fraction (30,000 g pellet) was subfractionated into mitochondria, plasma membrane and cytoskeleton. Analysis of the labeled proteins by SDS‐PAGE, autoradiography and densitometry revealed a T3‐induced increase of 50–80% for both tubulin and actin, only in the cytoskeleton fraction without any significant effect on the other fractions. Similar results were obtained when plasma membrane or cytoskeleton were isolated directly from labeled cerebrum by conventional methods instead of fractionating from the 30,000 g pellet. Analysis of relative stimulation of labeled tubulin and actin by T3 in cytoskeleton fraction derived from primary cultures of neuronal (N) and glial (G) cells labeled with 35‐methionine show that the stimulatory effect is predominantly on the N cells. Studies on the kinetics of induction of labeled tubulin and actin by T3 in the cytoskeleton fraction prepared from cerebra labeled with 35S‐methionine for 2, 8 and 18 hrs revealed no significant difference at 2 hrs; at 8 hrs, an increased incorporation into both tubulin and actin was reproducibly seen in the controls relative to T3‐treated samples. However by 18 hrs, this pattern reversed and an enhanced accumulation of both labeled tubulin and actin was observed under the influence of T3. The mechanism of this apparently intriguing effect of T3 on the kinetics of association of tubulin and actin with the cytoskeleton has been discussed in the light of the dual effect of the hormone on tubulin viz. enhancing its stability as well as rate of synthesis. The overall results indicate that the thyroid hormones play a major role in the cytoskeletal transport of tubulin and actin from their site of synthesis to that of assembly thus facilitating axodendritic outgrowth and morphological differentiation.
A clarification on conceptual and methodological issues related to the Job Characteristics Model
Authors: Rungtusanatham Manus , Anderson John C. 
Published: April 2003

AbstractWe provide a comment on ‘Comparing the effects of cellular and functional manufacturing on employees' perceptions and attitudes’ by Shafer, Tepper, Meredith, and Marsh (Journal of Operations Management, 1995, 12, 63–74). We identify and explicate three conceptual concerns related to their description of the Job Characteristics Model, as well as two methodological concerns with using the Job Diagnostic Survey to measure the five job characteristics and the Motivating Potential Score as an aggregate index of a job's ‘motivating potential’. We intend this explication to serve as a clarification and guidance for further conceptual and empirical research in operations management involving the Job Characteristics Model, the Job Diagnostic Survey, and the Motivating Potential Score. Our remarks are intended to be constructive and are offered in the spirit of scholarly advancement.