bluuebunny/crossref_metadata_2025_split huggingface dataset:
Somatosensory cortex of prosimian Galagos: Physiological recording, cytoarchitecture, and corticocortical connections of anterior parietal cortex and cortex of the lateral sulcus
Authors: Wu Carolyn W.‐H. , Kaas Jon H. 
Published: January 2003

AbstractCompared with our growing understanding of the organization of somatosensory cortex in monkeys, little is known about prosimian primates, a major branch of primate evolution that diverged from anthropoid primates some 60 million years ago. Here we describe extensive results obtained from an African prosimian, Galago garnetti. Microelectrodes were used to record from large numbers of cortical sites in order to reveal regions of responsiveness to cutaneous stimuli and patterns of somatotopic organization. Injections of one to several distinguishable tracers were placed at physiologically identified sites in four different cortical areas to label corticortical connections. Both types of results were related to cortical architecture. Three systematic representations of cutaneous receptors were revealed by the microelectrode recordings, S1 proper or area 3b, S2, and the parietal ventral area (PV), as described in monkeys. Strips of cortex rostral (presumptive area 3a) and caudal (presumptive area 1–2) to area 3b responded poorly to tactile stimuli in anesthetized galagos, but connection patterns with area 3b indicated that parallel somatosensory representations exist in both of these regions. Area 3b also interconnected somatotopically with areas S2 and PV. Areas S2 and PV had connections with areas 3a, 3b, 1–2, each other, other regions of the lateral sulcus, motor cortex (M1), cingulate cortex, frontal cortex, orbital cortex, and inferior parietal cortex. Connection patterns and recordings provided evidence for several additional fields in the lateral sulcus, including a retroinsular area (Ri), a parietal rostral area (PR), and a ventral somatosensory area (VS). Galagos appear to have retained an ancestoral preprimate arrangement of five basic areas (S1 proper, 3a, 1–2, S2, and PV). Some of the additional areas suggested for lateral parietal cortex may be primate specializations. J. Comp. Neurol. 457:263–292, 2003. © 2003 Wiley‐Liss, Inc.
Differential cholinergic activation of G proteins in rat and mouse brainstem: Relevance for sleep and nociception
Authors: Demarco George J. , Baghdoyan Helen A. , Lydic Ralph 
Published: January 2003

AbstractMurine models are increasingly used for investigations of sleep, yet no previous studies have characterized cholinergic activation of guanine nucleotide binding proteins (G proteins) in mouse brainstem nuclei known to regulate sleep. This study used in vitro [35S]guanylyl‐5′‐O‐(γ‐thio)‐triphosphate ([35S]GTPγS) autoradiography to test the hypothesis that muscarinic cholinergic receptors activate G proteins in C57BL/6J (B6) mouse brainstem. The nuclei studied are homologous to those known in rat and cat to modulate sleep and nociception. In B6 mouse, carbachol significantly increased specific binding of [35S]GTPγS in the pontine reticular nucleus, caudal part (79%); pontine reticular nucleus, oral part (131%); laterodorsal tegmental nucleus (56%); pedunculopontine tegmental nucleus (86%); dorsal raphe nucleus (53%); dorsal medial periaqueductal gray (54%); and ventrolateral periaqueductal gray (52%) when compared with basal binding. Carbachol‐induced G protein activation was concentration‐dependent and blocked by atropine, demonstrating mediation by muscarinic receptors. G protein activation by carbachol was heterogeneous across B6 mouse brainstem nuclei. Comparison of [35S]GTPγS binding between mouse and rat revealed different magnitudes of G protein activation in the pontine reticular formation. In the same pontine reticular formation area of B6 mouse where in vitro treatment with carbachol activates G proteins, in vivo microinjection of cholinomimetics causes a rapid eye movement sleep‐like state. These data provide the first direct measurement of muscarinic receptor‐activated G proteins in B6 mouse brainstem nuclei known in other species to regulate sleep. J. Comp. Neurol. 457:175–184, 2003. © 2003 Wiley‐Liss, Inc.
Distribution of keratin 8‐containing cell clusters in mouse embryonic tongue: Evidence for a prepattern for taste bud development
Authors: Mbiene Joseph‐Pascal , Roberts John David 
Published: January 2003

AbstractThe initiation of the morphogenesis of gustatory papillae is independent of innervation. To address the question of whether taste bud formation is associated with gustatory papilla morphogenesis, we examined developing tongues in mouse embryos from embryonic day 11 to birth. Despite the smooth morphological appearance of the lingual dorsal surface at 13 days of gestation, we observed embryonic taste bud primordia as discrete collections of cytokeratin 8‐positive and elongated cells in epithelial placodes in the anterior tongue. In subsequent stages until birth, cytokeratin 8 continues to be expressed in embryonic taste buds distributed in punctuate patterns at regular intervals along rows that are symmetrically located on both sides of the median sulcus in the dorsal anterior developing tongue. Embryonic taste buds were observed in the developing circumvallate papillae from 15.5 days of gestation until birth. The dorsal epithelium of the anterior tongue is not innervated when embryonic taste buds first occur. The increased numbers of embryonic taste buds in developing fungiform papillae until birth are not correlated with the neural invasion of the epithelium. Thus, taste buds occur prenatally more likely independently of the innervation. J. Comp. Neurol. 457:111–122, 2003. © 2003 Wiley‐Liss, Inc.
Inner S‐cone bipolar cells provide all of the central elements for S cones in macaque retina
Authors: Herr Steve , Klug Karl , Sterling Peter , Schein Stan 
Published: January 2003

AbstractSynaptic terminals of cones (pedicles) are presynaptic to numerous processes that arise from the dendrites of many types of bipolar cell. One kind of process, a central element, reaches deeply into invaginations of the cone pedicle just below an active zone associated with a synaptic ribbon. By reconstruction from serial electron micrographs, we show that L‐ and M‐cone pedicles in macaque fovea are presynaptic to ∼20 central elements that arise from two types of inner (invaginating) bipolar cell, midget and diffuse. In contrast, S‐cone pedicles, with more synaptic ribbons, active zones/ribbon, and central elements/active zone, are presynaptic to ∼33 central elements. Moreover, all of these arise from one type of bipolar cell, previously described by others, here termed an inner S‐cone bipolar cell. Each provides ∼16 central elements. Thirty‐three is twice 16; correspondingly, these bipolar cells are twice as numerous as S cones. (Specifically, each S cone is presynaptic to four inner S‐cone bipolar cells; in turn, each bipolar cell provides central elements to two S cones.) These bipolar cells are presynaptic to an equal number of small‐field bistratified ganglion cells, giving cell numbers in 2G:2B:1S ratios. Each ganglion cell receives input from two or more inner S‐cone bipolar cells and thereby collects signals from three or more S cones. This convergence, along with chromatic aberration of short‐wavelength light, suggests that S‐cone contributions to this ganglion cell's coextensive blue‐ON/yellow‐OFF receptive field are larger than opponent L/M‐cone contributions via outer diffuse bipolar cells and that opponent L/M‐cone signals are conveyed mainly by inner S‐cone bipolar cells. J. Comp. Neurol. 457:185–201, 2003. © 2003 Wiley‐Liss, Inc.
Developmental changes in the expression of chemokine receptor CCR1 in the rat cerebellum
Authors: Cowell Rita Marie , Silverstein Faye Sarah 
Published: January 2003

AbstractChemokines are small, soluble proteins that regulate leukocyte migration, adhesion, and proliferation. Recent evidence suggests that chemokine receptors are expressed in the central nervous system and that their functions extend beyond their roles in inflammation. Specific chemokines and their receptors are implicated in cerebellar development. In this study, we evaluated the expression of β‐chemokine receptor CCR1 in the immature and adult rat cerebellum and report striking developmental changes in CCR1 expression. Reverse transcriptase polymerase chain reaction assays of cerebellum revealed moderate increases in CCR1 mRNA expression from postnatal day (P) 3 to adulthood. Light and confocal microscopy were used to evaluate developmental changes in the neuroanatomical and cell‐specific distribution of CCR1 immunoreactivity. CCR1 immunoreactivity was detected as early as P3 and peaked between P7 and P21. The predominant CCR1‐immunoreactive neuronal cell types included granule cells of the internal granular layer, Purkinje cells, Golgi cells, and molecular layer interneurons; Bergmann glia, astrocytes, and resting microglia also expressed CCR1. In contrast, granule cells in the external germinal layer, descending granule cells, and activated microglia rarely expressed CCR1. We also evaluated the expression of the CCR1 ligand macrophage inflammatory protein‐1α (MIP‐1α/CCL3). Two cell populations expressed MIP‐1α: physiologically activated microglia in white matter (P7–P14) and Purkinje cells (P7–adult). MIP‐1α‐positive cells were frequently located near the processes and cell bodies of CCR1‐immunoreactive cells, during times of neuronal and glial maturation (second and third postnatal weeks). These findings provide support for the hypothesis that CCR1 plays a role in postnatal cerebellar development. J. Comp. Neurol. 457:7–23, 2003. © 2003 Wiley‐Liss, Inc.
Neurosecretory identity conferred by the apterous gene: Lateral horn leucokinin neurons in Drosophila
Authors: Herrero Pilar , Magariños Marta , Torroja Laura , Canal Inmaculada 
Published: January 2003

AbstractThe LIM‐HD protein Apterous has been shown to regulate expression of the FMRFamide neuropeptide in Drosophila neurons (Benveniste et al. [1998] Development 125:4757–4765). To test whether Apterous has a broader role in controlling neurosecretory identity, we analyzed the expression of several neuropeptides in apterous (ap) mutants. We show that Apterous is necessary for expression of the Leucokinin neuropeptide in a pair of brain neurons located in the lateral horn region of the protocerebrum (LHLK neurons). ap null mutants are depleted of Leucokinin in these cells, whereas hypomorphic mutants show reduced Leucokinin expression. Other Leucokinin‐containing neurons are not affected by mutations in ap gene. Co‐expression of apterous and Leucokinin is observed exclusively in the LHLK neurons, from larval stages to adulthood. Rescue assays performed in null ap mutants, by expressing Apterous protein under apGAL4 and elavGAL4 drivers, demonstrate the recovery of Leucokinin in the LHLK neurons. These results reinforce the emerging role of the LIM‐HD proteins in determining neuronal identity. They also clarify the neuroendocrine phenotype of apterous mutants. J. Comp. Neurol. 457:123–132, 2003. © 2003 Wiley‐Liss, Inc.
Expression of vesicular glutamate transporters, VGluT1 and VGluT2, in axon terminals of nociceptive primary afferent fibers in the superficial layers of the medullary and spinal dorsal horns of the rat
Authors: Li Jin‐Lian , Fujiyama Fumino , Kaneko Takeshi , Mizuno Noboru 
Published: January 2003

AbstractWe examined immunohistochemically whether the vesicular glutamate transporters (VGluTs), VGluT1 and VGluT2, might be expressed in synaptic terminals of nociceptive primary afferent fibers within laminae I and II of the medullary and spinal dorsal horns of the rat. VGluT1 immunoreactivity (IR) was intense in the inner part of lamina II but weak in lamina I and the outer part of lamina II. VGluT2‐IR was most intense in lamina I and the outer part of lamina II. Expression of VGluTs in synaptic terminals was confirmed by dual immunofluorescence histochemistry for VGluTs and synaptophysin. Expression of VGluTs in axon terminals of primary afferent fibers terminating in laminae I and II was also confirmed immunohistochemically after unilateral dorsal rhizotomy. The dual immunofluorescence histochemistry indicated expression of VGluTs in substance P (SP)‐containing axon terminals in lamina I and the outer part of lamina II. Electron microscopy confirmed the coexpression of VGluTs and SP in axon terminals within laminae I and II; VGluTs was associated with round synaptic vesicles at the asymmetric synapses. It was further observed that isolectin IB4, a marker for unmyelinated axons, often bound with VGluT2‐immunopositive structures but rarely with VGluT1‐immunopositive structures in lamina II. Thus, the results indicated in laminae I and II of the medullary and spinal dorsal horns that both VGluT1 and VGluT2 were expressed in axon terminals of primary afferent fibers, including SP‐containing nociceptive fibers and that VGluT in unmyelinated primary afferent fibers terminating in lamina II was primarily VGluT2. J. Comp. Neurol. 457:236–249, 2003. © 2003 Wiley‐Liss, Inc.
Fiber connections of the torus longitudinalis in a teleost: Cyprinus carpio re‐examined
Authors: Ito Hironobu , Yamamoto Naoyuki , Yoshimoto Masami , Sawai Nobuhiko , Yang Chun‐Ying , Xue Hao‐Gang , Imura Kosuke 
Published: January 2003

AbstractFiber connections of the carp torus longitudinalis were re‐examined by means of tract‐tracing methods. The torus longitudinalis projected mainly to the stratum marginale of the optic tectum, area pretectalis, and corpus cerebelli. The stratum marginale was anterogradely labeled only by biocytin, but not by horseradish peroxidase. Because the stratum is composed of extremely fine axons of the small toral neurons, this may be ascribed to different molecular weights of the tracers. The main afferent sources to the torus longitudinalis were the nucleus subvalvularis, which was located beneath the nucleus lateralis valvulae, the nucleus subeminentialis pars magnocellularis, and neurons along the posterior mesencephalo‐cerebellar tract. Some labeled cells also appeared in the area pretectalis, nucleus paracommissuralis, optic tectum, and torus semicircularis. In a previous paper, it was incorrectly reported that the valvula cerebelli was the main source of afferents to the torus longitudinalis. Here we report the reason for the previous mistake in relation to the techniques employed. J. Comp. Neurol. 457:202–211, 2003. © 2003 Wiley‐Liss, Inc.
Identification and localization of a neprilysin‐like activity that degrades tachykinin‐related peptides in the brain of the cockroach, Leucophaea maderae, and locust, Locusta migratoria
Authors: Isaac R. Elwyn , Nässel Dick R. 
Published: January 2003

AbstractNeprilysin (NEP) is an endopeptidase, which has an important role in the inactivation of mammalian tachykinins. NEP‐like activity has also been found in the brain of several insects; however, the lack of information about the cellular localization of this peptidase has hindered our understanding of its role in peptidergic signaling in insects. We now provide evidence that membrane‐bound NEP is involved in the inactivation of tachykinin‐related peptides in the brain of the cockroach, Leucophaea maderae, and the locust, Locusta migratoria. The L. maderae enzyme cleaved the cockroach peptide LemTRP‐1 and the mammalian NEP substrate [DAla2,Leu5]enkephalin at the Gly‐Phe peptide bond. The enzyme was acted upon by the NEP inhibitors phosphoramidon (IC50, 0.64 μM) and thiorphan (IC50, 1.23 μM), and the detergent‐solubilized enzyme had an Mr of approximately 300,000 and a neutral pH optimum. This endopeptidase cleaved another insect tachykinin‐related peptide, CavTK‐II, in a predictable manner at the Ala‐Phe peptide bond, suggesting that the peptidase can hydrolyse tachykinin‐related peptides with different structures. NEP activity was histochemically localized in several, but not all, regions of neuropil in the brain of L. maderae, including the central body, the lobula of the optic lobe, and the tritocerebrum. All of these regions are known to receive neuronal processes containing tachykinin‐related peptides. A slightly different distribution pattern for NEP was observed in the brain of L. migratoria. Again, NEP was localized to regions of the neuropil that also display tachykinin‐related peptide immunoreactivity. The data reported provide evidence for an evolutionary conserved role for NEP in the inactivation of tachykinin‐related peptides in the brain. J. Comp. Neurol. 457:57–66, 2003. © 2003 Wiley‐Liss, Inc.
Cerebrospinal fluid‐contacting neurons in the rat spinal cord, a γ‐aminobutyric acidergic system expressing the P2X2 subunit of purinergic receptors, PSA‐NCAM, and GAP‐43 immunoreactivities: Light and electron microscopic study
Authors: Stoeckel Marie‐Elisabeth , Uhl‐Bronner Sandra , Hugel Sylvain , Veinante Pierre , Klein Marie‐Jeanne , Mutterer Jerome , Freund‐Mercier Marie‐José , Schlichter Rémy 
Published: January 2003

AbstractCerebrospinal fluid‐contacting neurons (CSFcNs) occur in various brain regions of lower vertebrates. In mammals, they are restricted to medullospinal areas, and little is known about their projection sites. In the present work, we investigated some morphofunctional characteristics of such neurons in the rat spinal cord by light and electron microscopic immunocytochemistry. CSFcNs expressing the P2X2 subunit of purinergic receptors were present throughout the spinal cord, though more numerous at lower thoracolumbar and sacral levels. These neurons coexpressed GAD and the polysialylated neural cell adhesion molecule (PSA‐NCAM), a marker of cellular plasticity. From low thoracic levels downward, tiny amyelinic axons (less than 200 nm in diameter) were tightly packed in bundles, which ran along the ependyma and extended ventrally, eventually concentrating against the walls of the ventral median fissure. In addition to P2X2, GAD, γ‐aminobutyric acid (GABA), and PSA, these axons expressed GAP‐43 immunoreactivity. Moreover, they were labelled along their entire lengths with antibodies against synaptotagmin and synaptophysin, but these failed to reveal intraspinal terminal fields. Taken together, our observations indicate the presence in the rat spinal cord of a highly plastic system of GABAergic CSFcNs that express the P2X2 subunit of purinergic receptors. The function of this original system remains open to question. In these neurons, the P2X2 receptors may confer a sensitivity to ATP either present in the CSF or released by nearby neurons of the central autonomic area. J. Comp. Neurol. 457:159–174, 2003. © 2003 Wiley‐Liss, Inc.
Critical calpain‐dependent ultrastructural alterations underlie the transformation of an axonal segment into a growth cone after axotomy of cultured Aplysia neurons
Authors: Spira Micha E. , Oren Ruthi , Dormann Ada , Gitler Daniel 
Published: January 2003

AbstractThe transformation of a stable axonal segment into a motile growth cone is a critical step in the regeneration of amputated axons. In earlier studies we found that axotomy of cultured Aplysia neurons leads to a transient and local elevation of the free intracellular Ca2+ concentration, resulting in calpain activation, localized proteolysis of submembranal spectrin, and, eventually, growth cone formation. Moreover, inhibition of calpain by calpeptin prior to axotomy inhibits growth cone formation. Here we investigated the mechanisms by which calpain activation participates in the transformation of an axonal segment into a growth cone. To that end we compared the ultrastructural alterations induced by axotomy performed under control conditions with those caused by axotomy performed in the presence of calpeptin, using cultured Aplysia neurons as a model. We identified the critical calpain‐dependent cytoarchitectural alterations that underlie the formation of a growth cone after axotomy. Calpain‐dependent processes lead to restructuring of the neurofilaments and microtubules to form an altered cytoskeletal region 50–150 μm proximal to the tip of the transected axon in which vesicles accumulate. The dense pool of vesicles forms in close proximity to a segment of the plasma membrane along which the spectrin membrane skeleton has been proteolyzed by calpain. We suggest that the rearrangement of the cytoskeleton forms a transient cellular compartment that traps transported vesicles and serves as a locus for microtubule polymerization. We propose that this cytoskeletal configuration facilitates the fusion of vesicles with the plasma membrane, promoting the extension of the growth cone's lamellipodium. The growth process is further supported by the radial polymerization of microtubules from the growth cone's center. J. Comp. Neurol. 457:293–312, 2003. © 2003 Wiley‐Liss, Inc.
Reelin expression during embryonic brain development in Crocodylus niloticus
Authors: Tissir F. , Lambert De Rouvroit C. , Sire J.‐Y. , Meyer G. , Goffinet A.M. 
Published: January 2003

AbstractThe expression of reelin mRNA and protein was studied during embryonic brain development in the Nile crocodile Crocodylus niloticus, using in situ hybridization and immunohistochemistry. In the forebrain, reelin was highly expressed in the olfactory bulb, septal nuclei, and subpial neurons in the marginal zone of the cerebral cortex, dorsal ventricular ridge, and basal forebrain. At early stages, reelin mRNA was also detected in subventricular zones. In the diencephalon, the ventral lateral geniculate nuclei and reticular nuclei were strongly positive, with moderate expression in the habenula and focal expression in the hypothalamus. High expression levels were noted in the retina, the tectum, and the external granule cell layer of the cerebellum. In the brainstem, there was a high level of signal in cochleovestibular, sensory trigeminal, and some reticular nuclei. No expression was observed in the cortical plate or Purkinje cells. Comparison with reelin expression during brain development in mammals, birds, turtles, and lizards reveals evolutionarily conserved, homologous features that presumably define the expression profile in stem amniotes. The crocodilian cortex contains subpial reelin‐positive cells that are also p73 positive, suggesting that they are homologous to mammalian Cajal‐Retzius cells, although they express the reelin gene less intensely. Furthermore, the crocodilian cortex does not contain the subcortical reelin‐positive cells that are typical of lizards but expresses reelin in subventricular zones at early stages. These observations confirm that reelin is prominently expressed in many structures of the embryonic brain in all amniotes and further emphasize the unique amplification of reelin expression in mammalian Cajal‐Retzius cells and its putative role in the evolution of the cerebral cortex. J. Comp. Neurol. 457:250–262, 2003. © 2003 Wiley‐Liss, Inc.
Reflectivity of shock compressed xenon plasma
Authors: Reinholz H. , Röpke G. , Wierling A. , Mintsev V. , Gryaznov V. 
Published: January 2003

AbstractExperimental results [1] for the reflection coefficient of shock‐compressed dense xenon plasmas at pressures of 1.6 – 17 GPa and temperatures around 30 000 K using a laser beam with λ = 1.06 μm are compared with calculations based on different theoretical approaches to the dynamical collision frequency. It is found that a reasonable description can be given assuming a spatial electron density profile corresponding to a finite width of the shock wave front of about 2 · 10–6 m.