bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyneuronal innervation of spiny stellate neurons in cat visual cortex
Authors: Ahmed Bashir , Anderson John C. , Douglas Rodney J. , Martin Kevan A. C. , Nelson J. Charmaine 
Published: January 2005

AbstractOur hypothesis was that spiny stellate neurons in layer 4 of cat visual cortex receive polyneuronal innervation. We characterised the synapses of four likely sources of innervation by three simple criteria: the type of synapse, the target (spine, dendritic shaft), and the area of the presynaptic bouton. The layer 6 pyramids had the smallest boutons and formed asymmetric synapses mainly with the dendritic shaft. The thalamic afferents had the largest boutons and formed asymmetric synapses mainly with spines. The spiny stellates had medium‐sized boutons and formed asymmetric synapses mainly with spines. We used these to make a “template” to match against the boutons forming synapses with the spiny stellate dendrite. Of the asymmetric synapses, 45% could have come from layer 6 pyramidal neurons, 28% from spiny stellate neurons, and 6% from thalamic afferents. The remaining 21% of asymmetric synapses could not be accounted for without assuming some additional selectivity of the presynaptic axons. Additional asymmetric synapses may come from a variety of sources, including other cortical neurons and subcortical nuclei such as the claustrum. Of the symmetric synapses, 84% could have been provided by clutch cells, which form large boutons. The remainder, formed by small boutons, probably come from other smooth neurons in layer 4, e.g., neurogliaform and bitufted neurons. Our analysis supports the hypothesis that the spiny stellate receives polyneuronal innervation, perhaps from all the sources of boutons in layer 4. Although layer 4 is the major recipient of thalamic afferents, our results show that they form only a few percent of the synapses of layer 4 spiny stellate neurons.
Direct and indirect retinohypothalamic projections to the supraoptic nucleus in the female albino rat
Authors: Levine Joel D. , Zhao Xi‐Shun , Miselis Richard R. 
Published: January 2005

AbstractEarlier studies have shown that retinohypothalamic projections terminate extensively within the hypothalamus of the rat. Recently, we identified a light retinal projection to the supraoptic nucleus as well as a larger, well‐focused projection resulting in a peri‐supraoptic nucleus terminal field. In this study, we employed a double labeling method with cholera toxin conjugated to horseradish peroxidase (CT‐HRP) and pseudorabies virus, a transsynaptic neural tracer, to evaluate retinorecipient neurons in both the supraoptic nucleus and peri‐supraoptic nucleus terminal field. In addition, we looked for evidence that cells in the peri‐supraoptic nucleus terminal field project into the supraoptic nucleus. Three strains of pseudorabies virus were compared. A direct retinosupraoptic nucleus circuit was confirmed with all three strains. Retinorecipient neurons in the peri‐supraoptic nucleus terminal field were also confirmed. However, there was a strain‐based difference in the identification of these neurons. The wild‐type Becker strain labeled cells in the peri‐supraoptic nucleus terminal field in a manner paralleling the early, intermediate and late stages of infection of the suprachiasmatic nucleus. This parallel time course suggests that retinal ganglion cells terminate directly on cells in the peri‐supraoptic nucleus terminal field. Conversely, the Bartha and PRV‐91 strains showed appreciable labeling of peri‐supraoptic neurons only at long survival times. This longer time course suggests that these mutant strains label neurons in the peri‐supraoptic nucleus terminal field indirectly, after passing through additional neurons. In addition, experiments with monocular injection of CT‐HRP and posterior pituitary injection of pseudorabies virus showed retrogradely labeled second‐order cells in the peri‐supraoptic nucleus amidst the CT‐HRP labeled terminal field of the retinohypothalamic tract. These results demonstrate a direct projection from the retina to the supraoptic nucleus and provide evidence for an indirect circuit from the retina to the supraoptic nucleus via neurons located in the peri‐supraoptic nucleus terminal field. The strain‐based differences imply that those retinal ganglion cells that project to the peri‐supraoptic nucleus terminal field differ from those that project to the supra‐chiasmatic nucleus. In addition, these results suggest a neuroanatomic basis for photic effects on physiological mechanisms that are not mediated by the circadian timing system.
In situ hybridization detection of trka mRNA in brain: Distribution, colocalization with p75NGFR and up‐regulation by nerve growth factor
Authors: Gibbs Robert B. , Pfaff D. W. 
Published: January 2005

AbstractIn situ hybridization techniques were used to examine the distribution and the nerve growth factor (NGF) regulation of trkA mRNA in the adult rat brain in order to identify neurons in discrete regions of the brain that may be NGF responsive. In agreement with previous studies, trkA mRNA was detected within cells located in the medial septum (MS), diagonal band of Broca (DBB), and caudate. trkA mRNA was also detected in many other regions of the brain, including the nucleus basalis of Meynert, substantia innominata, paraventricular nucleus of the thalamus, interpeduncular nucleus, prepositus hypoglossal nucleus, vestibular nudei raphe obscuris, cochlear nucleus, sensory trigeminal nuclei, and gigantocellular as well as perigigantocellular neurons in the medullary reticular formation. By combining in situ hybridization detection of trkA mRNA with immunocytochemical detection ofp75NGFR, it was determined that the vast majority (> 90%) of the trkA mRNA‐containing cells detected in the MS and DBB also express p75NGFR. Likewise, the vast majority of p75NGFR‐IR cells detected in the MS and DBB expressed trkA mRNA. Intracerebroventricular infusions of NGF into the third ventricle adjacent to the preoptic area resulted in a 58% increase in relative cellular levels of trkA mRNA in the horizontal limb of the DBB. These data provide evidence that both p75NGFR and trkA are expressed by NGF‐responsive neurons in the MS and DBB. In addition, we note that areas that contained trkA mRNA and that also have been reported to contain p75NGFR are areas where high‐affinity NGF binding sites have been observed autoradio‐graphically, whereas areas that contain either trkA or p75NGFR alone are areas where no high‐affinity NGF binding has been reported. Together, these findings suggest that both trkA and p75NGFR play an important role in the formation of high‐affinity NGF receptors in brain and, furthermore, suggest that NGF may have physiological effects within many regions of the brain outside of the basal forebrain.
Regeneration of axons into the trochlear rootlet after anterior medullary lesions in the rat is specific for ipsilateral IVth nerve motoneurones
Authors: Derouiche Amin , Berry Martin , Sievers Jobst 
Published: January 2005

AbstractThe fibre projection from the IVth nerve nucleus to the superior oblique muscle was determined quantitatively in the normal rat by defining fibre numbers in transverse sections of the IVth nerve, and neurone numbers after retrograde labelling by horseradish peroxidase (HRP) injection into the muscle. There were 183 ± 27 (S.E.) labelled neurones in the nucleus contralateral to the injected muscle and only 2 ± 1 ipsilateral. The ipsilateral fibre number was 234 ± 7 and the cell/axon ratio 0.8 ± 0.1. Extensive analysis of all HRP retrogradely labelled material revealed no central fibre contribution to the IVth nerve other than from neurones resident in the trochlear nucleus.The central portion of the trochlear nerve tract was severed at its point of decussation in the anterior medullary velum. Ninety days after lesion, 10 ± 4 (6% of control) neurones were labelled in the ipsilateral trochlear nucleus; none were labelled in the contralateral nucleus or in any other part of the midbrain, pons, medulla, or cerebellum. The number of myelinated fibres in the IVth nerve had decreased to 21 ± 5 (9% of control) so that the cell/axon ratio was 0.4 ± 0.2, thus suggesting that a single motoneurone has more fibres after lesion. In electron micrographs of the IVth nerve, larger than normal numbers of unmyelinated fibres were seen. Many myelinated fibres displayed signs of abnormal myelination.After regeneration, the projection was exclusively ipsilateral and not crossed as in the normal. These findings establish that there is a high degree of specificity after regeneration since no myelinated central nervous system axons other than trochlear fibres select the IVth nerve root as a trajectory over which to regenerate.
Interconnections between the prefrontal cortex and the premotor areas in the frontal lobe
Authors: Lu Ming‐Teh , Preston James B. , Strick Peter L. 
Published: January 2005

AbstractWe examined interconnections between a portion of the prefrontal cortex and the premotor areas in the frontal lobe to provide insights into the routes by which the prefrontal cortex gains access to the primary motor cortex and the central control of movement. We placed multiple injections of one retrograde tracer in the arm area of the primary motor cortex to define the premotor areas in the frontal lobe. Then, in the same animal, we placed multiple injections of another retrograde tracer in and around the principal sulcus (Walker's area 46). This double labeling strategy enabled us to determine which premotor areas are interconnected with the prefrontal cortex.There are three major results of this study. First, we found that five of the six premotor areas in the frontal lobe are interconnected with the dorsolateral prefrontal cortex. Second, the major site for interactions between the prefrontal cortex and the premotor areas is the ventral premotor area. Third, the prefrontal cortex is interconnected with only a portion of the arm representation in three premotor areas (supplementary motor area, the caudal cingulate motor area on the ventral bank of the cingulate sulcus, and the dorsal premotor area), whereas it is interconnected with the entire arm representation in the ventral premotor area and the rostral cingulate motor area. These observations indicate that the output of the prefrontal cortex targets specific premotor areas and even subregions within individual premotor areas.
Expression of the tight junction protein ZO‐1 in the olfactory system: Presence of ZO‐1 on olfactory sensory neurons and glial cells
Authors: Miragall Fernando , Krause Dorothee , De Vries Uwe , Dermietzel Rolf 
Published: January 2005

AbstractThe olfactory system is a unique part of the central nervous system since it retains neuronal turnover and regenerative capacities in adulthood. Thus it provides an ideal model to study plasticity of membrane moities involved in cell‐cell interactions. One structure particularly involved in cell‐cell interaction is the tight junction, which establishes polarization of epithelial cells and creates diffusion barriers to paracellular passages. ZO‐1 is a phosphoprotein peripherally associated with tight junctions. We have studied expression of ZO‐1 protein in the developing and adult olfactory system of the mouse in order to get information about the localization and developmental expression of this tight junction component. ZO‐1 expression has also been determined in cell cultures of olfactory bulbs.ZO‐1 was present in the olfactory placode prior to formation of tight junctions. ZO‐1 was localized in the developing and mature olfactory epithelium at heterotypic contacts between supporting cells and olfactory neurons as well as at homotypic contacts between both these cell types. Confocal microscopy showed quantitative differences in the ZO‐1 expression among different olfactory dendrites. In the olfactory nerves ZO‐1 immunolabeling was detectable between olfactory ensheathing cells. From the seventh postnatal day ZO‐1 immunolabeling was detected at the mitral cell layer of the bulb on cells tentatively identified as oligodendrocytes. Myelinated tracts of the bulb were ZO‐1 negative. Cell cultures of olfactory bulbs showed ZO‐1 immunoreaction, mostly localized on glial fibrillary acidic protein (GFAP)‐positive cells.Our results provide further evidence that ZO‐1 serves functions unrelated to the tight junction complex and indicate molecular heterogeneity of these cell‐cell contacts.
In vitro autoradiographic localization of calcitonin binding sites in human medulla oblongata
Authors: Sexton Patrick M. , Paxinos George , Huang Xu‐Feng , Mendelsohn Frederick A. O. 
Published: January 2005

AbstractIn this study we examined the distribution of calcitonin (CT) binding sites in the human medulla oblongata by in vitro autoradiography. In competition studies, the rank order of potency for calcitonins competing for 125I‐salmon CT binding was salmon CT > porcine CT > human CT, which is consistent with physiologically relevant CT receptors in other systems. For the determination of CT binding in the human medulla, 20‐μm cryostat sections were incubated with 125I‐salmon CT in the presence or absence of 10−6 M unlabelled salmon CT to map specific CT binding sites. Punctate binding was observed over discrete nuclei of the medulla. High binding densities were seen over subnuclei of the dorsal motor nucleus of the vagus, the nucleus of the solitary tract, the intermediate reticular zone, the gigantocellular and dorsal paragigantocellular nuclei, and the raphe obscurus nucleus. Moderate levels of binding were observed over the lateral paragigantocellular nucleus and the rostral extent of the epiolivary nucleus. The cuneate and gracile nuclei and the fiber tracts did not contain detectable binding, while the inferior olivary nucleus had moderate levels of nonspecific binding. The localization of calcitonin binding sites in the human presents similarities but also important differences to the distribution in rat and cat. The most notable difference is the extreme binding densities in the intermediate reticular zone of the human. The location of binding sites suggests involvement of calcitonin in regulation of autonomic function.
Immunohistochemical analysis of the relation between 5‐hydroxytryptamine‐ and neuropeptide‐immunoreactive elements in the spinal cord of an amphibian (Xenopus laevis)
Authors: Pieribone Vincent A. , Brodin Lennart , Hökfelt Tomas 
Published: January 2005

AbstractIn mammals, a large proportion of the bulbospinal 5‐hydroxytryptamine (5‐HT) neurons also contain neuropeptides, such as substance P (SP) and galanin (GAL). To examine whether a similar coexistence occurs in an amphibian, an immunofluorescence double‐labelling technique was employed on sections of the Xenopus laevis spinal cord. Antisera raised against SP, GAL, enkephalin (ENK), corticotropin‐releasing factor (CRF), calcitonin gene‐related peptide (CGRP), and cholecystokinin (CCK) produced a labelling of fibers at all rostrocaudal levels of the spinal cord, with the highest fiber densities for SP and ENK and intermediate densities for GAL, CCK, and CGRP, while CRF‐immunoreactive fibers were barely detectable in intact animals. 5‐HT‐immunoreactive fibers were widely distributed in the spinal cord, and they often occurred in the vicinity of different types of peptide‐immunoreactive fibers. However, no coexistence between 5‐HT and the different peptide immunoreactivities could be detected, although SP and GAL immunoreactivities were sometimes found to be colocalized in the same fiber. Similar negative results were obtained when 5‐HT + SP‐ and 5‐HT + GAL‐labelled sections were examined in single focal planes with a confocal microscope. After a spinal transection, (survival period 6 weeks to 4 months), almost all 5‐HT‐immunoreactive fibers below the lesion were lost, and a build‐up of immunoreactive material occurred in fibers just rostral to the cut. In contrast, no significant loss of peptide‐immunoreactive fibers occurred, although some swollen SP‐, GAL‐, ENK‐, CRF‐, and CCK‐immunoreactive fibers were present rostral to the cut. The distribution of swollen peptide‐immunoreactive fibers did not overlap with that of the swollen 5‐HT‐immunoreactive fibers. Although negative immunohistochemical data must be inter‐preted with caution, in conjunction with previous studies (Brodin et al. [1988] J. Comp. Neurol. 271:1‐18; Sakamoto and Atsumi [1991] Cell Tissue Res. 264:221‐230), the present results indicate that bulbospinal 5‐HT neurons in nonmammalian vertebrates cocontain neuropeptides to a lesser extent than in mammals.
Parvalbumin, calbindin D‐28k, and calretinin immunoreactivity in the ascending auditory pathway of horseshoe bats
Authors: Vater Marianne , Braun Katharina 
Published: January 2005

AbstractIn the subcortical auditory system of Rhinolophus rouxi, antibodies directed against the calcium‐binding proteins parvalbumin, calbindin D‐28k, and calretinin yield partly overlapping and partly complementary labeling patterns which are described in detail for each nucleus.The most general features of the labeling patterns are that: (1) Parvalbumin is a potent marker for large and heterogenous populations of cells and puncta (presumed axon terminals) throughout the auditory pathway. (2) Immunostaining with the monoclonal calbindin‐antiserum was typically absent or sparse in most auditory brainstem centers, but prominent in auditory nerve fibers and in cells of the medial geniculate body (MGB). (3) Calretinin label is abundant but more restricted to subsets of auditory nuclei or subpopulations of cells than parvalbumin. (4) Calcium‐binding proteins are useful markers to define particular subregions or cell types in auditory nuclei: for example, (i) different labeling patterns are obtained within the nuclei of the lateral lemniscus and adjacent tegmental zones; (ii) in the inferior colliculus both calbindin‐ and calretinin‐antisera yield similar regional specific staining patterns, but label different cell types; (iii) subregions of the medial geniculate body have characteristic profiles of calcium‐binding proteins; and (iv) analyses of different nuclei showed that there is no simple common denominator for cells characterized by the expression of particular calcium‐binding proteins, nor does labeling correspond in a straightforward way with specific functional systems. (5) there are profound differences between the calbindin labeling patterns seen in Rhinolophus and those in other mammals.
Ventral root avulsion: An experimental model of death of adult motor neurons
Authors: Koliatsos Vassilis E. , Price William L. , Pardo Carlos A. , Price Donald L. 
Published: January 2005

AbstractThe present study proposes a reproducible model of experimental degeneration of adult motor neurons in the rat. Avulsion of ventral roots in the adult lumbar cord transects motor axons at the root exit and leads to retrograde cell death of 80% of motor neurons 2 weeks later; this result follows a series of retrograde changes, including chromatolysis, loss of transmitter phenotype, and accumulation of phosphorylated neurofilaments in perikarya. Glial cells recruited at the site of retrograde injury express both microglia‐specific epitopes (as exemplified by OX‐42 immunoreactivity) and macrophage‐specific markers (e.g., ED‐1 immunoreactivity). Macrophage‐specific markers become particularly intense 7 days postaxotomy and provide additional evidence of active phagocytosis of injured neurons. Ventral root avulsion is a very useful model for assessing mechanisms of motor neuron death and testing the ability of trophic factors and other agents to preserve the phenotype and promote the survival of adult motor neurons in vivo. © 1994 Wiley‐Liss, Inc.
Further characterization of the effects of brain‐derived neurotrophic factor and ciliary neurotrophic factor on axotomized neonatal and adult mammalian motor neurons
Authors: Clatterbuck Richard E. , Price Donald L. , Koliatsos Vassilis E. 
Published: January 2005

AbstractNeurotrophins and neural cytokines are two broad classes of neurotrophic factors. It has been reported that ciliary neurotrophic factor (CNTF) and brain‐derived neurotrophic factor (BDNF) prevent the degeneration of axotomized neonatal motor neurons. In addition, BDNF is transported retrogradely to α‐motor neurons following injection into the muscle, and patterns of BDNF expressed in spinal cord and muscle suggest a physiological role for this factor in motor neurons. In the present study, we characterize the effects of BDNF on axotomized neonatal facial motor neurons and extend these observations to adult models of motor neuron injury (axotomy‐induced phenotypic injury of lumbar motor neurons). BDNF reduces axotomy‐induced degeneration of neonatal neurons by 55% as determined by Nissl staining (percentage of surviving neurons in vehicle‐treated cases, 25%; in BDNF‐treated cases, 80%). Rescued neurons have an intact organelle structure but appear smaller and slightly chromatolytic on electron microscopic analysis. As demonstrated by intense retrograde labeling with horseradish peroxidase (HRP) applied to the proximal stump of the facial nerve, neurons rescued by BDNF have intact mechanisms of fast axonal transport. CNTF did not appear to have significant effects on neonatal motor neurons, but the lack of efficacy of this factor may be caused by its rapid degradation at the application site. BDNF is not capable of reversing the axotomy‐induced reduction in transmitter markers [i.e., the acetylcholine‐synthesizing enzyme choline acetyl‐transferase (ChAT) or the degrading enzyme acetylcholinesterase (AChE)] in neonatal or adult animals or the axotomy‐induced up‐regulation of the low‐affinity neurotrophin receptor p75NGFR (nerve growth factor receptor) in adult motor neurons. However, BDNF appears to promote the expression of p75NGFR in injured neonatal motor neurons. In concert, the findings of the present study suggest that BDNF can significantly prevent cell death in injured motor neurons. However, this neurotrophin may not be a retrograde signal associated with the induction and/or maintenance of some mature features of motor neurons, particularly their transmitter phenotype. © 1994 Wiley‐Liss, Inc.