bluuebunny/crossref_metadata_2025_split huggingface dataset:
Serotoninergic and nonserotoninergic neurons in the medullary raphe system have axon collateral projections to autonomic and somatic cell groups in the medulla and spinal cord
Authors: Allen Gary V. , Cechetto David F. 
Published: January 2005

AbstractFluorescent double retrograde‐tracing studies combined with fluorescent immunostaining for serotonin were carried out to determine the potential patterns of divergence in axonal projections to autonomic and somatic motor sites from medullary raphe and parapyramidal neurons. Injections (20–60 nl) of combinations of fluorescent retrograde tracers (Fast Blue, fluoro‐gold, green latex microspheres, Diamidino Yellow) were made into the intermediolateral cell column (IML) of the spinal cord and the brainstem lateral tegmental field or ventral horn of the lumbar spinal cord of male Wistar rats. The animals were perfused after a 7–10‐Day survival period, and the brains were removed, sectioned (50μm), and immunostained for serotonin.Following injections of different retrograde‐tracer substances into the IML of the thoracic cord and the ventral horn of the lumbar cord, 36% of the neurons with axon collateral projections to the IML and the lumbar ventral horn were serotoninergic. Following injections of different retrograde‐tracer substances into the IML and the lateral tegmental field, 26% of the neurons with axon collateral projections to the IML and the lateral tegmental field were serotoninergic. Many of the medullary neurons with projections to the lateral tegmental field and the lumbar cord were located dorsal and lateral to those neurons with projections to the IML. The results indicate that serotoninergic and nonserotoninergic neurons of the midline raphe system and parapyramidal region have axon collateral branches to the IML and the lateral tegmental field or the IML and the lumbar ventral horn. These projection neurons may form the anatomical substrate for the integration of autonomic and somatic motor activity.
Pyramidal and nonpyramidal callosal cells in the striate cortex of the adult rat
Authors: Martínez‐García Fernando , González‐Hernández Tomás , Martínez‐Millán Luis 
Published: January 2005

AbstractThe aim of this study has been to determine the neuronal types (pyramidal and nonpyramidal) within the rat's visual cortex, which project through the corpus callosum. To this end, the morphology and laminar distribution of callosal cells have been investigated by combining Diamidino Yellow retrograde tracing with intracellular injection of Lucifer Yellow in slightly fixed tissue slices.The visual callosal projection arises from pyramidal cells of diverse morphology in layers II to VIb, as well as from several modified pyramids located mainly in layers II, IV (star pyramids) and VIb (horizontal or inverted pyramids and related forms of spiny stellate cells). Our results indicate that in rats, as in other mammals, several types of nonpyramidal neurons also contribute to the contralateral projection. Bitufted cells in layers II–III and V were found to project contralaterally. Moreover, a spine‐free layer V cell and a sparsely spiny multipolar neuron of layer IV were also labeled. In both stellate cells, partial axonal labeling reveals that these callosal cells display a local axonal arborization. Finally, our results of retrograde transport with Diamidino Yellow and with another sensitive retrograde tracer, the beta subunit of the cholera toxin, demonstrate for the first time that the two main neuronal types of layer I participate in the callosal projection. In layer I, several small horizontal cells of the inner half of layer I and a large subpial cell displaying long radiating dendrites were also injected. The latter cell may correspond to the Cajal‐Retzius cell of the adult rat.In spite of the important differences in the organization of the visual system between rodents and cats, the callosal projection in both mammals is composed of a large variety of pyramidal cells and several nonpyramidal neurons. This high morphological diversity suggests that the callosal projection is much more physiologically complex than the extracortical efferents of the visual cortex, resembling other cortico‐cortical connections. The roles that the different callosal cells may play in the processing of visual information are discussed in relation to the known functions of the corpus callosum.
NADPH‐diaphorase neurons in the retina of the hamster
Authors: Lau Kam Cheung , So Kwok‐Fai , Tay David , Leung Mason Chin Pang 
Published: January 2005

AbstractNADPH‐diaphorase‐positive neurons have been demonstrated in the inner nuclear layer and ganglion cell layer of the retina of different mammalian species, but so far no experiments have been conducted to identify whether these cells are amacrine cells and/or retinal ganglion cells. We attempted to solve this problem by studying the NADPH‐diaphorase‐positive neurons in the hamster retina.From the NADPH‐diaphorase histochemical reaction, two distinct types of neurons in the hamster retina were identified. They were named ND(g) and ND(i) cells. The ND(g) cells were cells with larger somata, ranging from 10 to 21 μm in diameter with a mean of 15.58 μm (S.D.= 2.59). They were found in the ganglion cell layer only. The ND(i) cells were smaller, with the somata ranging from 7 to 11 μm and having the mean diameter of 8.77 μm (S.D. = 1.24). Most of the ND(i) cells were found in the inner nuclear layer, and only very few could be observed in the inner plexiform layer. On average, there were 8,033 ND(g) and 5,051 ND(i) cells in the ganglion cell layer and inner nuclear layer, respectively.Two experiments were performed to clarify whether any of the NADPH‐diaphorase neurons were retinal ganglion cells. Following unilateral optic nerve section, which leads to the retrograde degeneration of retinal ganglion cells, the numbers of both ND(g) and ND(i) cells did not change significantly for up to 4 months. In addition, when retinal ganglion cells were prelabeled retrogradely (horseradish peroxidase of flurescent microspheres) and retinas were then stained for NADPH diaphorase, no double‐labeled neurons were detected. These results indicated that the NADPH‐diaphorase neurons in the hamster retina were the amacrine cells in the inner nuclear layer and displaced amacrine cells in the ganglion cell layer.Dendrites of the ND(g) and ND(i) cells were found to stratify in sublaminae 1, 3, and 5 of the inner plexiform layer, with a prominent staining in the sublamina 5. The possible importance of this arrangement in the rod pathway is also discussed. © 1994 Wiley‐Liss, Inc.
Corticorubral synaptic organization in Macaca fascicularis: A study utilizing degeneration, anterograde transport of WGA‐HRP, and combined immuno‐GABA‐gold technique and computer‐assisted reconstruction
Authors: Ralston Diane Daly 
Published: January 2005

AbstractThe macaque red nucleus receives afferents from two major sources, the cerebral cortex and the deep cerebellar nuclei. Approximately 90% of the corticorubral afferent axons project to pars parvicellularis of the red nucleus, the neurons of which transmit information to the cerebellum by way of the inferior olivary nucleus. The remaining 10% project to pars magnocellularis of the red nucleus, the major projection of which is to the spinal cord. In this study, corticorubral terminations labeled following lesions or injections of wheatgerm agglutinin conjugated to horseradish‐peroxidase into the topographically defined hand area of the primary motor cortex were quantitatively studied via electron microscopy. Cortical afferent terminals within pars parvicellularis and pars magnocellularis synapse upon all regions of the dendritic arbors of rubral projection neurons. However, the majority of these labeled afferents synapse upon thin‐diameter shafts or presumed spinous processes of rubral distal dendrites as well as upon vesicle‐containing profiles of presynaptic dendrites of local circuit interneurons that are γ‐aminobutyric acid‐immunoreactive, as identified by postembedding immunohistochemistry. Synaptic contacts formed by the labeled cortical terminal were large in width and extended through several serial sections. Synaptic contacts formed by the presynaptic dendritic profiles, on the other hand, were more punctate and could be seen in only one or two serial sections. These latter synaptic interactions probably provide a modification of the effects of cortical input to rubral projection neurons as suggested by previous physiological studies that indicated the dominance of cortical input onto distal dendrites as well as involvement with inhibitory circuits. An example of the complexities of these synaptic interactions is further demonstrated by a three‐dimensional computer reconstruction. This quantitative study of corticorubral afferents in the macaque monkey provides insight into the interactions of cerebral cortical afferents with rubral projection neurons and their relationship with local circuit inhibitory interneurons to elucidate the role played by the cortex in the activation of rubral neurons. © 1994 Wiley‐Liss, Inc.
Medullary visceral reflex circuits: Local afferents to nucleus tractus solitarii synthesize catecholamines and project to thoracic spinal cord
Authors: Mtui E. P. , Anwar M. , Reis D. J. , Ruggiero D. A. 
Published: January 2005

AbstractVisceral feedback circuits in lower brainstem were elucidated with retrograde tracers by mapping neurons that issue local projections to the general visceral afferent division of the nucleus tractus solitarii (NTS) and dorsomotor vagal nucleus (DMX) in adult male rats. In study 1, spinal and intramedullary afferents to the visceral‐sensorimotor complex (NTS‐X) were traced to contiguous populations of cell bodies arranged in cylindrical segmental organization. NTS‐X afferents derive from curvilinear arrays of neurons that parallel the efferent radiations of the solitariotegmental tract. Newly discovered afferents arise from circumscribed cell groups in the dorsal reticular formation and periventricular zone. Another source was traced to a paraambigual cell column in the apex of the rostral ventrolateral reticular nucleus (n.RVL). In study 2, catecholaminergic afferents were initially defined with combined retrograde transport‐immunocytochemical methods. Deposits of retrograde tracers into NTS‐X transported to neurons containing tyrosine hydroxylase (TH) in the A1, C1, and C3 areas or phenylethanolamine N‐methyltransferase (PNMT) in the C1 area of the n.RVL and C3 area. In study 3, it was revealed that NTS‐X afferents arise, in part, as collaterals of thoracic reticulospinal neurons. Deposits of the retrograde fluorescent tracer Fluorogold into the upper thoracic cord and rhodamine‐labeled microbeads into NTS‐X transported to the same neurons within a subambigual locus in n.RVL and parts of nucleus raphe magnus. In study 4, dual retrograde tracer‐immunocytochemical analysis demonstrated that catecholamines are synthesized by a subset of neurons in the n.RVL that issue collaterals to the NTS‐X and thoracic cord. Double retrogradely labeled TH‐or PNMT‐immunoreactive cell bodies were restricted to the C1 area within a 450‐μm column bordered rostrally by the facial nucleus and ventrally by the medullary subpial surface. We conclude that visceral reflex arcs are reciprocally organized. Targets of NTS projection are also sources of local NTS‐X afferent innervation. Catecholaminergic and other local afferents from reticular formation, periventricular, and spinal gray may, via collaterals, simultaneously modulate visceral reflex excitability at the level of NTS and the outflow of autonomic and respiratory motoneurons. © 1995 Willy‐Liss, Inc.
Nervus terminalis ganglion of the bonnethead shark (Sphyrna tiburo): Evidence for cholinergic and catecholaminergic influence on two cell types distinguished by peptide immunocytochemistry
Authors: White Joel , Meredith Michael 
Published: January 2005

AbstractThe nervus terminalis is a ganglionated vertebrate cranial nerve of unknown function that connects the brain and the peripheral nasal structures. To investigate its function, we have studied nervus terminalis ganglion morphology and physiology in the bonnethead shark (Sphyrna tiburo), where the nerve is particularly prominent. Immunocytochemistry for gonadotropin‐releasing hormone (GnRH) and Leu‐Pro‐Leu‐Arg‐Phe‐NH2 (LPLRFamide) revealed two distinct populations of cells. Both were acetylcholinesterase positive, but LPLR‐Famide‐immunoreactive cells consistently stained more darkly for acetylcholinesterase activity. Tyrosine hydroxylase immunocytochemistry revealed fibers and terminal‐like puncta in the ganglion, primarily in areas containing GnRH‐immunoreactive cells.Consistent with the anatomy, in vitro electrophysiological recordings provided evidence for cholinergic and catecholaminergic actions. In extracellular recordings, acetylcholine had a variable effect on baseline ganglion cell activity, whereas norepinephrine consistently reduced activity. Electrical stimulation of the nerve trunks suppressed ganglion activity, as did impulses from the brain in vivo. During electrical suppression, acetylcholine consistently increased activity, and norepinephrine decreased activity. Muscarinic and, to a lesser extent, α‐adrenergic antagoinsts both increased activity during the electrical suppression, suggesting involvement of both systems. Intracellular recordings revealed two types of ganglion cells that were distinguishable pharmacologically and physiologically. Some cells were hyperpolarized by cholinergic agonists and unaffected by norepinephrine; these cells did not depolarize with peripheral nerve trunk stim stimulation. Another. Another group of cells did depolarize with peripheral trunk stimulation; a representative of this group was depolarized by carbachol and hyperpolarized by norepinephrine.These and other data suggest that the bonnethead nervus terminal is ganglion contains at least two cell populations that respond differently to acetylcholine and norepinephrine. The bonnethead nervus terminals ganglion appears to differ fundamentally from sensory and autonomic ganglia but does share some features with the neural circuits of forebrain GnRH systems. © 1995 Willy‐Liss, Inc.
Analysis of dendritic spines in rat CA1 pyramidal cells intracellularly filled with a fluorescent dye
Authors: Trommald Mart , Jensen Vidar , Andersen Per 
Published: January 2005

AbstractThe dendritic branching pattern and the distribution of dendritic spines were studied in hippocampal neurones with an improved technique. In slices taken from adult Wistar rats, CA1 pyramidal cells were filled with Lucifer yellow and examined under a laser‐scanning confocal microscope.The basal dendrites were found evenly distributed inside a regular cupola‐shaped volume. Their total length was about 4,500 μm. The branches divided between one and three times, with the initial segments comprising less than 2%, and the long terminal segments (mean length, 119 μm) including more than 80% of the total length of the basal dendrites. The apical dendritic branches emerged obliquely from the main shaft, ran for a distance of 50 to 250 μm, and made up a total length of about 5,100 μm in stratum radiatum and between 1,100 and 3,200 μm in stratum lacunosum‐moleculare. The mean total length of the dendritic tree was 11,900 μm. All values were corrected for shrinkage. Shrinkage was measured in three dimensions and was 20.2% in the horizontal (x/y) plane and 40.9% in the vertical (z) plane.Both the basal and the apical dendritic branches were covered by regularly spaced spines. When corrected for dehydration‐induced shrinkage and for hidden spines, the density was 1.80 and 2.00 spines/μm dendritic length for the basal and apical dendritic branches, respectively. Apart from the initial parts of the branches, which had few or no spines, the spines were remarkably evenly spaced. In particular, the distance between spine heads was significantly different from a random distribution, suggesting a regulatory process for the spacing of spines. © 1995 Wiley‐Liss, Inc.
Localization of 5‐HT2A receptor mRNA by in situ hybridization in the olfactory bulb of the postnatal rat
Authors: McLean John H. , Darby‐King Andrea , Paterno Gary D. 
Published: January 2005

AbstractThe olfactory bulb receives a dense serotonergic input and appears to require serotonergic input in early olfactory associational learning. However, it is not known which cell types receive the serotonergic input or whether the cells express markers for the input throughout life. These issues need resolution in order for the mechanisms of serotonergic interactions to be better understood. The mRNA for the 5‐HT2A receptor was localized in the olfactory bulb of postnatal day 1, 2, 14 and 9‐month‐old Sprague‐Dawley rats as well as in the bulb of adult (6 months) and aged (22‐30 month) Fisher 344 rats by in situ hybridization using an 35S‐labelled 5‐HT2A specific oligonucleotide probe mixture. In all animals, hybridization was observed in mitral cells which are the major output cells of the main olfactory bulb. Tufted cells, located in the external plexiform layer and juxtaglomerular region, were readily observed in adult and aged animals and were also observed, albeit not as readily, in neonate pups. Quantitative analysis of the silver grain density over cells confirmed qualitative observations and showed that mitral and tufted cells were labelled in the neonate as well as in adult and aged animals. Labelled cells were also numerous in the external division of the anterior olfactory nucleus in all animals. 5‐HT2A receptor mRNA could not be detected either qualitatively or quantitatively by in situ hybridization in the accessory olfactory bulb, nor could it be observed in the olfactory epithelium. The results suggest that the output cells of the main olfactory bulb receive serotonergic input via 5‐HT2A receptors and that the serotonergic input onto these cells could influence olfactory functioning at all postnatal ages. © 1995 Wiley‐Liss, Inc.
Substance P, bombesin, and leucine‐enkephalin immunoreactivities are restored in the frog tectum after optic nerve regeneration
Authors: Humphrey M. F. , Renshaw G. M. C. , Kitchener P. D. , Beazley L. D. 
Published: January 2005

AbstractExtensive regeneration of the optic nerve takes place in adult Amphibia. In this study, we have determined whether one aspect of retinotectal organisation, namely immunoreactive laminae in the retinorecipient layers of the optic tectum, is restored after optic nerve regeneration. To do so, the distributions of substance‐P, bombesin, and leucine‐enkephalin immunoreactivities were examined in the optic tectum of the frog Litoria (Hyla) moorei. Results of a normal series were compared with those at intervals up to 84 days and at 196 days after either unilateral deafferentation or optic nerve crush.In the normal series, distinct neuropeptide immunoreactive laminae were located within the retinorecipient tectal layers. There were two major laminae with substance‐P, two with bombesin, and one with leucine‐enkephalin immunoreactivities. Additional faint laminae of both substance‐P and bombesin immunoreactivity were present in the tectal region that receives input from the visual streak. In addition, labelling of cell bodies and dendrites was seen elsewhere in the tectum.All except one immunoreactive lamina changed after deafferentation. The deeper of those with substance‐P immunoreactivity, along with both bombesin laminae, were eventually lost the lamina with leucine‐enkephalin immunoreactivity was halved in intensity. We assume that these laminae are wholely or, in the case of the leucine‐enkephalin lamina, partially associated with primary optic input. By contrast, the more superficial lamina with substance‐P immunoreactivity remained unchanged and is presumably not directly related to visual input.During nerve regeneration, the intensity of all laminae associated with optic input initially fell as in the deafferentation series but, in the long term, recovered to approximately 80% of normal intensities. We conclude that ganglion cells associated with each of the immunoreactivities tested had successfully regenerated. The reduced intensity of immunoreactivities after regeneration is due presumably in part to the cell loss from the ganglion cell population.Furthermore, we discuss the findings of similar studies for Rana pipiens (Kuljis and Karten [1983] J. Comp. Neurol. 217:239–251 and [1985] 240:1–15) in light of the present findings. We argue that some of the previous observations can be reinterpreted to indicate that regeneration was not limited to ganglion cells associated with substance‐P immunoreactivity as first thought. © 1995 Wiley‐Liss, Inc.
Differential distribution of six calcium‐binding proteins in the rat olfactory epithelium during postnatal development and adulthood
Authors: Bastianelli Enrico , Polans Arthur S. , Hidaka Hiroyoshi , Pochet Roland 
Published: January 2005

AbstractOdorant stimulation of receptor cells results in a calcium influx that activates the transduction pathway. Ca2+ acceptors, such as calmodulin, may mediate between the change in intracellular calcium and the conductance mechanism underlying the initial electrical event. Ca2+ acceptors also may participate in subsequent processing of olfactory information. The identification and characterization of these molecules, therefore, should provide important information about the complex signal transduction pathway involving calcium in olfaction as well as other sensory systems.The present study describes the distribution of six calcium‐binding proteins in the rat main olfactory epithelium during postnatal development to determine when different Ca2+ acceptors can be detected and whether they segregate into different layers or p6 rtions of the epithelium. Calmodulin, calretinin, calbindin‐D28k, neurocalcin, and recoverin were detected immunohistochemically in olfactory receptors but not in basal cells. S‐100 immunoreactivity was restricted to glial cells primarily around the cribriform plate. During postnatal development (from P1 to P20), calmodulin, calretinin, calbindin‐D28k, and neurocalcin formed a gradient of immunoreactivity descending from the central to the lateral areas in the nasal cavity, whereas recoverin was expressed only in sporadic, mature receptors in the proximal region of the mucosa. At P20, the immunoreactivity pattern for each calcium‐binding protein was identical to the adult profile, indicating that the olfactory epithelium had reached maturity by this stage. Olfactory nerve fiber bundles displayed a differential staining pattern from P 1 until adulthood for calbindin‐D28k and calretinin (internal portions of bundles). Differential calmodulin immunoreactivity of olfactory nerves (large external portions of bundles) appeared at P10. The immunoreactivity of the nerve fiber bundles may reflect a further degree of organization relevant to odor discrimination. © 1995 Wiley‐Liss, Inc.