bluuebunny/crossref_metadata_2025_split huggingface dataset:
Light microscopic and ultrastructural analysis of GABA‐immunoreactive profiles in the monkey spinal cord
Authors: Carlton Susan M. , Hayes Elizabeth S. 
Published: January 2005

AbstractIt is hypothesized that terminals containing γ‐aminobutyric acid (GABA) participate in presynaptic inhibition of primary afferents. To date, few convincing GAB A‐immunoreactive (GABA‐IR) axo‐axonic synapses have been demonstrated in support of this theory. The goal of this study is to document the relationship between GABA‐IR profiles and central terminals in glomerular complexes in lumbar cord of the monkey (Macaca fascicularis). In addition, the relationship between GABA‐IR profiles and other neural elements are analyzed in order to better understand the processing of sensory input in the spinal cord.GABA‐IR cell bodies were present in Lissauer's tract (LT) and in all laminae in the spinal gray matter except lamina IX, GABA‐IR fibers and terminals were heavily concentrated in LT: laminae I, II, and III; and present in moderate concentration in the deeper laminae of the dorsal horn, ventral horn (especially in association with presumed motor neurons), and lamina X. Electron microscopic analysis confined to LT and laminae I, II, and III demonstrated GABA‐IR cell bodies, dendrites, and myelinated and unmyelinated fibers. GABA‐IR cell bodies received sparse synaptic input, some of which was immunoreactive for GABA. The majority of the synaptic input to GABA‐IH neurons occurred at the dendritic level. Furthermore, the presence of numerous vesicle‐containing GABA‐IR dendrites making synaptic interactions indicated that GABA‐IR dendrites also provided a major site of output. Two consistent arrangements were observed in laminae I–III concerning vesicle‐containing GABA‐IR dendrites: (1) they were often postsynaptic to central terminals and (2) they participated in reciprocal synapses. The majority of GABA‐IR axon terminals observed contained round clear vesicles and varying numbers of dense core vesicles. Only on rare occasions were GABA‐IR terminals with flattened vesicles observed. GABA‐IR terminals were not observed as presynaptic elements in axo‐axonic synapses; however, on some occasions, GABA‐IR profiles presumed to be axon terminals were observed postsynaptic to large glomerular type terminals.Our findings suggest that a frequent synaptic arrangement exists in which primary afferent terminals relay sensory information into a GABAergic system for further processing. Furthermore, GABA‐IR dendrites appear to be the major source of input and output for this inhibitory system. The implications of this GABAergic neurocircuitry are discussed in relation to the processing of sensory input in the superficial dorsal horn and in terms of mechanisms of primary afferent depolarization (PAD).
Supraspinal projections to the ventromedial lumbar spinal cord in adult male rats
Authors: Shen Peter , Arnold Arthur P. , Micevych Paul E. 
Published: January 2005

AbstractIn the present study, the fluorescent tract tracing compound Fluorogold was used to study the afferents of the SNB (spinal nucleus of the bulbocavernosus), which is found in the ventromedial spinal grey and innervates penile muscles of the male rat. Fluorogold was iontophoretically injected into the SNB, which was located by recording antidromic activation of the motoneurons after stimulating the bulbocavernosus muscle, Retrogradely labeled cells were found in laminae I, V–IX, and area X of the lumbar spinal cord, suggesting segmental input to the SNB. Supraspinally, the greatest number of labeled cells were in the medulla oblongata, particularly in the lateral vestibular nucleus, gigantocellular reticular nucleus, and ventral and alpha divisions of the gigantocellular reticular nucleus. Labeled cells were also observed in the medullary raphe nuclei, the ventral medullary nucleus, and the spinal vestibular nucleus. In the pons, labeled cells were observed in the nucleus locus coeruleus, nucleus subcoeruleus, and caudal pontine reticular nucleus. No labeled cells were present in the cerebellum, rostral pons, mesencephalon, and cerebral cortex. The most rostral occurrence of labeled cells was in the medial parvicellular division of the hypothalamic para ventricular nucleus. These potential afferents to the SNB identified in male rats imply that the inputs to motoneurons that innervate sex‐specific muscles involved in male reproductive behavior may be similar to the inputs to lumbar motoneurons described in the female rat that innervate muscles involved in female sexual behavior.
Axonal regeneration and sprouting following injury to the cerebral–buccal connective in the snail Achatina fulica
Authors: Croll Roger P. , Baker Michael W. 
Published: January 2005

AbstractAxonal sprouting and regeneration were studied in the land snail Achatina fulica following a unilateral crush to the cerebral–buccal connective. Both normal projection patterns and changes induced by injury were examined with axonal filling techniques. As expected, most staining was lost shortly after the crush when filling across the lesion site. Much of this decrease is attributable to the direct disruption of fiber pathways, but evidence also indicates that a limited amount of retraction of some neurites occurred during the first week. A subsequent, gradual increase in the numbers of stained elements culminated in supernumerary counts of fibers in many pathways and in some novel labeling of cell bodies, Maximum numbers of supernumerary fibers usually occurred 21–28 days after the lesion. Most of these extra neurites and cell bodies subsequently disappeared, and by day 35 the appearance of projections generally returned to within the ranges observed in normal, unlesioned animals. Together the results demonstrate the extent of neuritic regeneration, sprouting, and retraction that occurs in vivo within the gastropod nervous system following injury. The study also indicates the usefulness of such in vivo approaches to understand the long‐term processes that contribute to the restoration of morphological and functional integrity.
Development of two morphological types of retinopetal fibers in chick embryos, as shown by the diffusion along axons of a carbocyanine dye in the fixed retina
Authors: Frttzsch B. , de Caprona M.‐D. Crapon , Clarke P. G. H. 
Published: January 2005

AbstractCentrifugal fibers to the retinas of chick embryos and hatched chicks have been examined and traced following staining by diffusion along their axonal membranes of the carbocyanine dye DiI in fixed tissue.In the older embryos and hatched chicks, the report of Dogiel (Arch. Mikrosk. Anat. 44:622–648, 1895) has been confirmed that there are two very different morphological types of centrifugal fiber. The restricted type ends as a relatively thick fiber, lacking varicosities, that runs for a short distance in the most sclerad level of the inner plexiform layer before terminating in a pericellular nest overlying the flask‐shaped body of a single amacrine cell. Thin filaments occasionally leave the pericellular net, apparently to terminate on adjacent cells. The widespread type also runs in the most sclerad level of the inner plexiform layer, but it is thin, varicose, and highly branched, and its terminal arbor may span more than 1 mm, remaining at the same level. Both types of terminal arbor issue from parent axons in the optic fiber layer of the retina. A single parent axon gives either a single terminal fiber of the restricted type or several terminals of the widespread type, but never a mixture of the two. It is argued that the restricted and widespread types originate respectively from the neurons of the contralateral isthmo‐optic nucleus and from the “ectopic” neurons scattered outside the isthmo‐optic nucleus.In development, the centrifugal fibers reach the retina between E9 and E10 and initially run radially in the optic fiber layer, parallel to the retinofugal fibers but avoiding the dorsal retina. They dive into the inner plexiform layer at about E12. By E13, the terminal arbors are forming, and the widespread and restricted types can already be distinguished. The widespread type continues to increase its territory until about E18, and then appears to remain stable, whereas the restricted type attains its maximum ramification between E13 and E15 and then contracts. Prior to the retraction, the terminal territories of the restricted type fibers overlap, which may provide the anatomical basis for the interaxonal competition that apparently contributes to neuronal death in the isthmo‐optic nucleus between E13 and E16. Axons of ganglion cells exhibit transient side branches between E11 and E13; these never reach as deep as the level where the centrifugal fibers run.
Connections of the retrosplenial granular a cortex in the rat
Authors: van Groen Thomas , Michael Wyss J. 
Published: January 2005

AbstractAlthough the retrosplenial granular a cortex (Rga) is situated in a critical position between the hippocampal formation and the neocortex, few studies have examined its connections. The present experiments use both retrograde and anterograde tracing techniques to characterize the afferent and efferent connections of Rga. Cortical projections to Rga originate in the ipsilateral area infraradiata, the retrosplenial agranular and granular b cortices, the ventral subiculum, and the contralateral Rga. Subcortical projections originate in the claustrum, the diagonal band of Broca, the thalamus, the midbrain raphe nuclei, and the locus coeruleus. The thalamic projections to Rga originate mainly in the anterodorsal (AD) and laterodorsal (LD) nuclei, with sparse projections arising in the anteroventral (AV) and reuniens nuclei. Each projection to Rga terminates in distinct layers of the cortex. The thalamic projection from AD terminates primarily in layers I, 111, and IV of Rga, whereas the s o n s arising from the LD nucleus have a dense terminal plexus only in layer I. The projections arising from the subiculum end predominantly in layer 11, whereas the postsubiculum projects to layers I and 111‐V. Axons from the contralateral Rga form a dense terminal plexus in layers IV and V, with a smaller number of terminals in layers I and VI. Rga projects ipsilaterally to the AV and LD nuclei of the thalamus and to the anterior cingulate, retrosplenial agranular, and postsubicular cortices. Contralaterally it projects to the retrosplenial agranular and Rga cortices. Rga projections to the thalamus terminate ipsilaterally in the dorsal part of LD and bilaterally in AV. Together, these data suggest that Rga integrates thalamic with limbic information.
Segregation of afferent projections in the central nervous system of the leech Hirudo medicinalis
Authors: Peinado Alejandro , Zipser Birgit , Ml Eduardo R. 
Published: January 2005

AbstractSensory axons originating in peripheral tissues converge onto each segmental ganglion in the central nervous system (CNS) of the leech, where they segregate into well‐defined regions of the synaptic neuropil. Here we report on several aspects of the molecular and anatomical organizations of these afferent projections1 that bear upon the hypothesis that surface markers are involved in organizing these axons as they grow into the CNS. First, we show that the distribution of some surface markers in the adult is restricted to axons of peripheral origin and is not present on the neighboring axons of central neurons. Second, we demonstrate that the number of afferents increases postembryonically as the leech increases in size, suggesting that at least some of the cues employed by afferent axons to grow to appropriate central targets must be present throughout the life of the animal. We then show, using anterograde axonal tracing and immunohistochemistry, that there is both convergence and divergence of afferent axons into highly specific regions of the neuropil. Lastly, we examine the distribution of surface markers present on different subsets of afferents and show that axons having one type of marker segregate from those having the second type.Our results, considered together with previous observations in this system, provide new clues about the organization of afferent projections in the nervous system of the leech. They also suggest how a relatively small number of molecular markers might mediate fiber‐fiber interactions to organize afferent axons as they grow into the CNS.
Nuclei of origin of monoaminergic, peptidergic, and cholinergic afferents to the cat trigeminal motor nucleus: A double‐labeling study with cholera‐toxin as a retrograde tracer
Authors: Fort Patrice , Luppi Pierre‐Herve , Sakai Kazuya , Salvert Denise , Jouvet Michel 
Published: January 2005

AbstractThe aim of the present study was to determine the brainstem afferents and the location of neurons giving rise to monoaminergic, cholinergic, and peptidergic inputs to the cat trigeminal motor nucleus (TMN). This was done in colchicine treated animals by using a very sensitive double immunostaining technique with unconjugated cholera‐toxin B subunit (CT) as a retrograde tracer.After CT injections in the TMN, retrogradely labeled neurons were most frequently seen bilaterally in the nuclei reticularis parvicellularis and dorsalis of the medulla oblongata, the alaminar spinal trigeminal nucleus (magnocellular division), and the adjacent pontine juxta‐trigeminal region and in the ipsilateral mesencephalic trigeminal nucleus. We further observed that inputs to the TMN arise from the medial medullary reticular formation (the nuclei reticularis magnocellularis and gigantocellularis), the principal bilateral sensory trigeminal nucleus, and the dorsolateral pontine tegmentum.In addition, the present study demonstrated that the TMN received (1) serotonergic afferents, mainly from the nuclei raphe obscurus, pallidus, and dorsalis; (2) catecholaminergic afferent projections originating exclusively in the dorsolateral pontine tegmentum, including the Kölliker‐Fuse, parabrachialis lateralis, and locus subcoeruleus nuclei; further, that (3) methionin‐enkephalin‐like inputs were located principally in the medial medullary reticular formation (nuclei reticularis magnocellularis and gigantocellularis and nucleus paragigantocellularis lateralis), in the caudal raphe nuclei (Rpa and Rob) and the dorsolateral pontine tegmentum; (4) substance P‐like immunoreactive neurons projecting to the TMN were present in the caudal raphe and Edinger‐Westphal nuclei; and 5) cholinergic afferents originated in the whole extent of the nuclei reticularis parvicellularis and dorsalis including an area located ventral to the nucleus of the solitary tract at the level of the obex.In the light of these anatomical data, the present report discusses the possible physiological involvement of TMN inputs in the generation of the trigeminal jaw‐closer muscular atonia occurring during the periods of paradoxical sleep in the cat.
Distribution of parvalbumin immunoreactivity in the visual cortex of Old World monkeys and humans
Authors: Blümcke Ingmar , Hof Patrick R. , Morrison John H. , Celio Marco R. 
Published: January 2005

AbstractThe macaque visual system has been frequently used as a model for understanding functional aspects of human vision. There are, however, few studies directly comparing biochemically defined neuronal populations in the visual cortex of the two species.In this study we compared the distribution and morphological features of the parvalbumin‐immunoreactive neuronal subpopulation within humans and Old World monkeys (Macaca fascicularis and Macaca mulatta) by using monoclonal antibodies against the Ca2+‐binding protein parvalbumin (PV), a neuronal marker in the vertebrate cerebral cortex. Characteristic laminar density and distribution of PV is observed, matching that seen with cytochrome C‐oxidase and γ‐aminobutyric acid (GABA) immunoreactivity. Thus, parvalbumin is prominent in the layers receiving afferents from the dorsal lateral geniculate nucleus. Terminal fields are rich in layer IVA and IVC and moderate in the blob‐region of layer II–III of the monkey cortex. In the human visual cortex only layer IVC displays rich terminal fields. Parvalbumin is present in neurons within all layers of the cortex except layer I. Parvalbumin‐immunoreactive (PV‐ir) axons occur in different lamellae of the white matter containing axons belonging to association or projection neurons. The estimation of PV‐ir neurons, determined for 50 μm‐wide columns through the thickness of area 17, shows that the percentage of the total neuron number in area 17 of humans containing PV is 6.8 ± 2.0%, and in the macaque monkey, 11.5 ± 2.9%. The perikaryal area of PV‐ir neurons varies according to the layer and is comparable in humans (109.3 ± 40.8 μm2) and monkeys (94.3 ± 29.5 μm2). However, the relative number of large PV‐ir neurons is higher in humans. The immunoreactive product fills the thinnest cell processes and the shape of PV‐ir neurons can be easily traced with the aid of a camera lucida. The shape of the neurons is similar in the two species studied, and they probably belong to non‐spiny stellate, double‐bouquet, chandelier, and basket cell classes.This study shows that parvalbumin acts as a marker for a subpopulation of interneurons in area 17, but it is also present in the geniculocortical as well as in corticocortical pathways. Moreover, the Old World monkey and human visual cortices have a similar, but not identical, distribution of this important calcium‐binding protein.
Sources of subcortical GABAergic projections to the superior colliculus in the cat
Authors: Appell Peter P. , Behan Mary 
Published: January 2005

AbstractThe goal of this study was to identify GABAergic input to the cat superior colliculus from neurons located in the caudal diencephalon, mesencephalon, pons and medulla. Cells efferent to the superior colliculus were labeled retrogradely with the tracer horseradish peroxidase, and an antibody to gamma‐aminobutyric acid was used to label GABAergic neurons in the same sections.The results indicate that neurons in several distinct areas of the caudal diencephalon and brainstem are both immunocytochemically labeled for GABA and retrogradely labeled with horseradish peroxidase. These areas include zona incerta, nucleus of the posterior commissure, anterior and posterior pretectal nuclei, nucleus of the optic tract, superior colliculus, cuneiform nucleus, subcuneiform area, substantia nigra pars reticulata and pars lateralis, periparabigeminal area, external nucleus of the inferior colliculus, the area ventral to the external nucleus of the inferior colliculus, mesencephalic reticular formation, dorsal and ventral nuclei of the lateral lemniscus, and the perihypoglossal nucleus.The role that such diverse inhibitory input to the superior colliculus might play, particularly in influencing eye movements, is discussed.
Extrinsic projections from area CA1 of the rat hippocampus: Olfactory, cortical, subcortical, and bilateral hippocampal formation projections
Authors: Van Groen Thomas , Wyss J. Michael 
Published: January 2005

AbstractHippocampal area CA1 provides the major cortical output of the hippocampus, but only its projections to the subiculum and lateral septal nucleus are well characterized. The present study reexamines these extrinsic projections by using anterograde and retrograde tracing techniques. Injections of the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA‐L) in the septal one‐third of CA1 label axons and terminals in subicular, postsubicular, retrosplenial, perirhinal, and entorhinal cortices, lateral septal nucleus, and diagonal band of Broca. The septal CA1, injections also label terminal fields in contralateral CA1, and in contralateral subicular, postsubicular, perirhinal, and entorhinal cortices. Injections into the splenial one‐third of CA1 label axons and terminals in subiculum, postsubiculum, ventral area infraradiata, and lateral septal nucleus, but they do not label axons and terminals on the contralateral side of the brain. Injections in the temporal one‐third of CA1 label axons and terminals in subicular, parasubicular, entorhinal, and infraradiata cortices, anterior olfactory nucleus, olfactory bulb, lateral septal nucleus, nucleus accumbens, amygdala, and hypothalamus. The temporal CA1 injections label no axons on the contralateral side of the brain. These data demonstrate that CA1 has more widespread projections than previously appreciated, and they provide the first clear evidence that CA1 projects to the contralateral cortex and to the ipsilateral olfactory bulb, amygdala, and hypothalamus. The results also demonstrate a heterogeneity in the efferent projections originating in different septotemporal levels of CA1.
Distribution of mu, delta, and kappa opioid receptor binding sites in the brain of the one‐day‐old domestic chick (Gallus domesticus): An in vitro quantitative autoradiographic study
Authors: Csillag Andras , Bourne Rachel C. , Stewart Michael G. 
Published: January 2005

AbstractThree highly specific opioid ligands—[D‐Ala2, Gly‐ol.]‐enkephalin (DAGO) for mu (m̈) receptor sites, [D‐Pen2, D‐Pen5]‐enkephalin (DPDPE) for delta (δ) sites, and U‐69593 for kappa (κ) sites—were used to determine the regional distribution of the three major subtypes of opioid receptor binding sites in the brains of 1‐day‐old domestic chicks by the technique of quantitative receptor autoradiography. Whilst there was a degree of heterogeneity in the binding levels of each of the ligands, some notable similarities existed in the binding of the μ and κp ligands in several forebrain regions, and in the optic tectum of the midbrain where μ and δ binding was very high. In the forebrain there was a high level of binding of μ and κ ligands in the hyperstriatum, and for the μ ligand there was a very distinct lamination of binding sites in hyperstriatum accessorium, intercalatum supremum, dorsale and ventrale. Levels of binding of the μ and κ ligands were also high in nucleus basalis, and (for μ only) in the neostriatum. The distribution of binding of the δ specific ligand in the forebrain showed marked differences to that of μ and κ, being particularly low in the hyperstriatum and neostriatum. Very high levels of labelling of δ binding sites were, however, found in the nucleus rotundus. Binding of the three ligands was generally low or absent in the cerebellum and medulla, apart from a distinct labelling of the granule cell layer by the μ‐ligand. A kinetic analysis was made of the binding of the three ligands to whole forebrain sections using scintillation counting methods. The μ‐ligand DAGO had the highest affinity, KD (1.0 n mol L−1), followed by the κ ligand U69593 (4.6 n mol L−1), and then the δ ligand DPDPE (6.0 n mol L−1). The Bmax varied from 14.6 f mol/mg tissue for the μ ligand to 6.3 fmol/mg tissue (δ), and 4.3 fmol/mg tissue (κ). However, an analysis of the kinetics of binding of the μ, δ, and κ ligands to individual forebrain regions by quantitative receptor autoradiography revealed a considerable variation in the affinity for binding sites and in maximal binding levels. A previous study was made of the distribution of the three opioid binding sites in adult pigeon brain by Reiner et al. (Journal of Comparative Neurology 280:359–382, 1989). The present data show some similarities to the earlier study, but there are also marked dissimilarities which may be due either to species specific, or age related, differences. In the domestic chick the greatest densities of opiate receptor binding sites appear to coincide with regions involved in higher order sensory processing and memory storage.