bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neurotransmitter receptors in the proliferative zones of the developing primate occipital lobe
Authors: Lidow Michael S. , Rakic Pasko 
Published: January 2005

AbstractFilm autoradiography was used to investigate the expression of several neurotransmitter receptor subtypes in the transient ventricular and subventricular proliferative zones of the developing occipital lobe in two groups of macaque monkey fetuses. The first group of fetuses were between 60 and 93 days after conception (E60‐E93), when the ventricular and subventricular zones of the monkey occipital lobe produce neurons destined for the visual cortex. In the second group, fetuses were between E107 and E128, after generation of cortical neurons has ceased. In the E60–E93 group of fetuses, ventricular and subventricular zones displayed high densities of 5‐HT1‐serotonergic, D1‐dopaminergic, α1‐and α2‐adrenergic and high affinity kainate receptors. The activation of these receptors has previously been shown to stimulate cell proliferation in other cell systems. The possible involvement of these receptors in regulation of neuronal production is also supported by their absence in the deep laminae of the embryonic cerebral wall after E107, after cortical neurogenesis has been completed. The only exception is a high density of α2‐adrenergic receptors maintained near the ventricular surface long after all cortical neurons have been generated. We also found that during neurogenesis, proliferative zones in E66–E90 fetuses displayed virtually no 5‐HT2‐serotonergic, D2‐dopaminergic, β‐adrenergic, M1‐muscarinic cholinergic, gamma aminobutyric acid (GABA)A, N‐methyl‐D‐aspartate (NMDA), or β‐amino‐3‐hydroxy‐5‐menthy‐4‐isoxazole proprionate (AMPA) sites; most of these receptor subtypes have been reported to mediate the suppression of cell proliferation. The present findings suggest that dividing and/or newly generated cortical neurons are capable of receiving specific signals from multiple neurotransmitters present in their environment. © 1995 Wiley‐Liss, Inc.
Early olfactory enrichment and deprivation both decrease β‐adrenergic receptor density in the main olfactory bulb of the rat
Authors: Woo Cynthia C. , Leon Michael 
Published: January 2005

AbstractThe density of noradrenergic locus coeruleus projections and β‐adrenergic receptors in the main olfactory bulb of the rat increases with age. Both β1 and β2 receptor subtypes exhibit laminar distributions, with focal regions of high receptor density present within the neuropil of individual glomeruli. Since the first synaptic contacts between olfactory receptor neurons and bulbar neurons occur within the glomeruli, early olfactory experiences possibly could influence the density or distribution of β‐adrenergic receptors in the bulb. We therefore investigated the effects of olfactory deprivation and early olfactory enrichment on the density and distribution of β‐adrenergic receptors in the main olfactory bulb. Animals were subjected to either unilateral naris closure on postnatal day 1 or odor training from postnatal days 1–18. Bulbs were removed on postnatal day 19 and subjected to quantitative autoradiography using the β‐adrenergic receptor antagonist [125I]iodopindolol and specific receptor subtype antago nists ICI 118,551 (β2‐antagonist) and ICI 89,406 (β1‐antagonist). Unilateral naris occlusion decreased both the number of β2 glomerular foci and the density of β1 and β2 receptors in the deprived bulb compared to the nondeprived bulb. Early odor training resulted in a significant decrease in the number, area, and receptor density of 2 glomerular foci in the midlateral region of the bulb. The distribution of 2 glomerular foci also differs with these two sensory manipulations. Changes in β‐adrenergic receptor density in response to both early learning and olfactory deprivation may be induced by a transient increase in olfactory bulb norepinephrine. © 1995 Wiley‐Liss, Inc.
Tissue plasminogen activator mRNA expression in granule neurons coincides with their migration in the developing cerebellum
Authors: Freidman Glenn C. , Seeds Nicholas W. 
Published: January 2005

AbstractTissue plasminogen activator activity in the developing cerebellum, as quantified by zymography of cerebellar homogenates from embryonic day (E) 17 to adult mice, shows a peak of activity at postnatal day (P) 7, followed by a steady 75% decrease into adulthood. Northern blot analysis reveals a similar pattern for tissue plasminogen activator mRNA levels, which are low at E17 but increase dramatically, reaching their highest levels of specific mRNA/μg RNA in P1–P7 mice and declining about threefold in the adult mouse. In situ hybridization of whole mouse brain sections with a tissue plasminogen activator antisense cRNA probe shows pronounced reactivity in the cerebellum. Although some binding is associated with the cerebellar meninges, the external granule layer is devoid of tissue plasminogen activator mRNA at all ages. However, highly labeled elongated cells, which also bind antibody to neuronal nuclear antigen and are adjacent to Bergmann glial fibers (i.e., migrating granule neurons), are readily visible throughout the molecular and Purkinje layers at P7 and P14. In the adult mouse cerebellum, tissue plasminogen activator mRNA labeling is restricted to cells in the Purkinje/internal granule layers. Thus, tissue plasminogen activator gene expression is induced as granule neurons leave the external granule layer and begin their inward migration. © 1995 Wiley‐Liss, Inc.
Development of cairetinin immunoreactivity in the neocortex of the rat
Authors: Fonseca Montserrat , Del Río José A. , Martínez Albert , Gómez Sonia , Soriano Eduardo 
Published: January 2005

AbstractThe prenatal and postnatal development of calretinin (CR)‐containing elements in the neocortex of the rat was analyzed using immunohistochemistry. CR immunoreactivity in the cortical anlage appeared early at embryonic day 14 (E14), with CR‐positive neurons located in the primitive plexiform layer and in the emerging subplate and marginal zones. At later prenatal and early postnatal stages, these two layers showed the highest CR immunostaining in the cortex, and large numbers of cell bodies and fibers were immunostained. From postnatal day 3 (P3) onwards, CR immunostaining disappeared progressively from the subplate‐layer VIb and the marginal zone‐layer I, so that very few cells remained stained in these layers in the adult. In the cortical plate and prospective layers VIa to II–III, CR‐positive neurons were seen at prenatal stages, their numbers increasing markedly during the first postnatal week. Most neurons showed undifferentiated nonpyramidal shapes, and matured during the second and third postnatal weeks, when the adult pattern of CR immunostaining was achieved. In addition, some pyramidal‐like neurons in the infragranular layers and in layer II–III transiently expressed CR during the postnatal period, most notably between P3 and P12. Colocalization experiments performed at P0–P3 with antibodies against the neurotransmitter γ‐aminobutyricacid (GABA) showed that most nonpyramidal CR‐positive neurons in the derivates of the cortical plate were also GABAergic during development. In contrast, large numbers of CR‐containing neurons in the subplate and marginal zone were GABA‐negative. The present results show that in addition to recording the early development of a subset of nonpyramidal neurons, CR is transiently expressed in certain GABA‐negative populations of the subplate and marginal zone, and most likely in pyramidal neurons. © 1995 Wiley‐Liss, Inc.
Molecular basis of interactions between regenerating adult rat thalamic axons and Schwann cells in peripheral nerve grafts II. Tenascin‐C
Authors: Zhang Y. , Campbell G. , Anderson P. N. , Martini R. , Schachner M. , Lieberman A. R. 
Published: January 2005

AbstractTenascin‐C is a developmentally regulated extracellular matrix component. There is evidence that it may be involved in axon growth and regeneration in peripheral nerves. We have used in situ hybridization and immunocytochemistry to investigate the association of tenascin‐C with central nervous system axons regenerating through a peripheral nerve autograft inserted into the thalamus of adult rats. Between 3 days and 4 weeks after implantation, tenascin‐C immunoreactivity was increased in the grafts, first at the graft/brain interface, then in the endoneurium of the graft, and finally within the Schwann cell columns of the graft. By electron microscopy, reaction product was present around collagen fibrils and basal laminae in the endoneurium, but the heaviest deposits were found at the surface of regenerating thalamic axons within Schwann cell columns. Schwann cell surfaces were not associated with tenascin‐C reaction product except where they faced the tenascin‐rich basal lamina or were immediately opposite axons surrounded by tenascin‐C. By 8 weeks after graft implantation tenascin‐C in the endoneurium and around axons of the graft was decreased. In the brain parenchyma aroundthe proximal part of the graft, axonal sprouts associated with tenascin‐C could not be identified earlier than 2 weeks after grafting and were sparse at this stage. Larger numbers of such axons were present at 8–13 weeks after grafting and were located predominantly where the glia limitans between brain and graft appeared to be incomplete, suggesting that the tenascin‐C may have penetrated the brain parenchyma from the graft. By in situ hybridization, cells expressing tenascin‐C mRNA (probably Schwann cells) appeared first at the brain/graft interface 3 days after grafting and thereafter were mainly located within the grafts. Lightly labelled cells containing tenascin‐C mRNA (probably glial cells) were scattered in the thalamic parenchyma both ipsilateral and contralateral to the graft and a few heavily labelled cells were located very close to the tip of the graft. These results show that regenerating adult thalamic axons, unlike regenerating peripheral axons, become intimately associated with peripheral nerve graft‐derived tenascin‐C, suggesting that they express a tenascin‐C receptor, as many neurons do during development, and that tenascin‐C derived from Schwann cells may play a role in the regenerative growth of such axons through the grafts. © 1995 Wiley‐Liss, Inc.
Cell and molecular analysis of the developing and adult mouse subventricular zone of the cerebral hemispheres
Authors: Gates Monte A. , Thomas L. Brannon , Howard Eugene M. , Laywell Eric D. , Sajin Boris , Faissner Andreas , Götz Bernhard , Silver Jerry , Steindler Dennis A. 
Published: January 2005

AbstractThe subventricular zone (SVZ) of the lateral ventricle remains mitotically active in the adult mammalian central nervous system (CNS). Recent studies have suggested that this region may contain neuroñal precursors (neural stem cells) in adult rodents. A variety of neuronal and glial markers as well as three extracellular matrix (ECM) markers were examined with the hope of understanding factors that may affect the growth and migration of neurons from this region throughout development and in the adult. This study has characterized the subventricular zone of late embryonic, postnatal, and adult mice using several neuronal markers [TuJ1, nicotinamide adenine dinucleotide phosphate diaphorase (NADPH‐d), neuron‐ specific enolase (NSE)], glial markers [RC‐2, vimentin, glial fibrillary acidic protein (GFAP), galactocerebroside (Gal‐C)], ECM markers [tenascin‐C (TN‐C), chondroitin sulfate, a chondroi tin sulfate proteoglycan termed dermatan sulfate‐dependent proteoglycan‐1 (DSD‐1‐PG)], stem‐cell marker (nestin), and proliferation‐specific marker [bromodeoxyuridine (BrdU)]. TuJ1+ and nestin+ cells (neurons and stem cells, respectively) persist in the region into adulthood, although the numbers of these cells become more sparse as the animal develops, and they appear to be immature compared to the cells in surrounding forebrain structures (e. g., not expressing NSE and having few, if any, processes). Likewise, NADPH‐d+ cells are found in and around the SVZ during early postnatal development but become more sparse in the prolifera tive zone through maturity, and, by adulthood, only a few labeled cells can be found at the border between the SVZ and surrounding forebrain structures (e. g., the striatum), and even smaller numbers of positive cells can be found within the adult SVZ proper. BrdU labeling also seems to decrease significantly after the first postnatal week, but it still persists in the SVZ of adult animals. The disappearance of RC‐2+ (radial) glia during postnatal development and the persistence of glial‐derived ECM molecules such as tenascin and chondroitin sulfate proteoglycans (as well as other “boundary” molecules) in the adult SVZ may be associated with a persistence of immaturity, cell death, and a lack of cell emigration from the SVZ in the adult. © 1995 Wiley‐Liss, Inc.
Thyrotropin‐releasing hormone inputs are preferentially directed towards respiratory motoneurons in rat nucleus ambiguus
Authors: Sun Qi‐Jian , Pilowsky Paul , Llewellyn‐Smith Ida J. 
Published: January 2005

AbstractIn the present study, we assessed the extent of the thyrotropin‐releasing hormone (TRH) input to motoneurons in the ambigual, facial, and hypoglossal nuclei of the rat using a combination of intracellular recording, dye filling, and immunohistochemistry. Twelve motoneurons in the rostral nucleus ambiguus were labelled by intracellular injection in vivo of Neurobiotin (Vector). Seven out of 12 ambigual motoneurons displayed rhythmic fluctuations of their membrane potential in phase with phrenic nerve discharge, whereas the other five had no modulations of any kind. Seven facial motoneurons and seven hypoglossal motoneurons were also filled with Neurobiotin. All three motor nuclei contained TRH‐immunoreactive varicosities, with the largest numbers found in the nucleus ambiguus. Close appositions were seen between TRH‐immunoreactive boutons and every labelled motoneuron. Respiratory‐ related motoneurons in the nucleus ambiguus received the largest number of TRH appositions with 74 ± 38 appositions/neuron (mean ± S. D.; n = 7). In contrast, nonrespiratory ambigual motoneurons received significantly fewer TRH appositions (11 ± 5; n = 5;P< 0. 05; Mann‐Whitney U test). Facial motoneurons received about the same number of TRH appositions as nonrespiratory ambigual motoneurons, with 13 ± 4 (n = 7). Hypoglossal motoneurons received the fewest appositions from TRH‐containing boutons, with 8 ± 2 (n = 7). There were no differences in the TRH inputs to respiratory and nonrespiratory motoneurons in the facial and hypoglossal nuclei. These results demonstrate that, among motoneurons in the medulla, respiratory motoneurons in the rostral nucleus ambiguus are preferentially innervated by the TRH‐immunoreactive boutons. © 1995 Wiley‐Liss Inc.
Synaptic inputs to single neurons in the lateral geniculate nuclei of normal and monocularly deprived squirrel monkeys
Authors: Wilson James R. , Forestner Donna M. 
Published: January 2005

AbstractNeurons in the dorsal lateral geniculate nucleus (dLGN) of normal and monocularly lid‐sutured squirrel monkeys were recorded electrophysiologically, and some were injected intracellularly with horseradish peroxidase (HRP) to examine and compare their synaptic inputs. Limited tests of the receptive field properties did not show any differences between the normal, nondeprived, or deprived neurons.Sixteen injected neurons were examined at the light microscopic level with most of these located in the P‐laminae (n = 14). Ten of these were either from normal monkeys (n = 9) or received input from the nondeprived eye of a monocularly deprived monkey (n = 1). The remaining six neurons received input from the deprived eye. The dendritic trees of deprived neurons did not differ from those of normal or nondeprived neurons. Three normal and five deprived neurons from the P‐laminae were examined at the electron microscopic level. Afferent distributions were not significantly different between normal and deprived neurons. Retinal, cortical, and gamma aminobutyric (GABA) ergic afferents accounted for nearly all inputs (avg., 42%, 23%, and 32%, respectively) and selectively contacted proximal, distal, or all parts of the dendrites.Overall, synaptic densities (synapses per length of dendrite) were high proximally and decreased with distance from the soma. However, the synaptic densities onto deprived neurons were higher at all distances compared to those onto normal neurons. Furthermore, HRP‐filled deprived neurons received an average of 25 synapses onto their somata compared with only an average of 7 somal synapses on the HRP‐fihled normal neurons. Most of the increase in the number of synapses onto the deprived neurons was from GABAergic type profiles. This abnormality of the deprived neurons of the dLGN could be the underlying cause of their lesser responses compared with normal or nondeprived dLGN neurons. It could also be the initial stage that causes blindness in monocularly lid‐sutured primates. © 1995 Wiley‐Liss Inc.
Representation of the face and intraoral structures in area 3b of the squirrel monkey (Saimiri sciureus) somatosensory cortex, with special reference to the ipsilateral representation
Authors: Manger Paul R. , Woods Timothy M. , Jones Edward G. 
Published: January 2005

AbstractStudies of the representation of the trigeminal nerve in the thalamus and cerebral cortex of mammals have revealed representations of both contra‐ and ipsilateral intraoral structures. However, the relative extent of both representations is subject to considerable species variation. The present study employed microelectrode mapping and anatomical tracing to investigate the location and extent of the ipsilateral representation in area 3b of the somatosensory cortex of squirrel monkeys. A small region, approximately 2 mm2, was found to be responsive to stimulation of ipsilateral intraoral structures. This region was located on the anteromedial border of area 3b, surrounded by the representation of the contralateral roof of the mouth. This region corresponded to areas of intense anterograde labeling following injections placed in the ventromedial portion of the ventral posterior medial nucleus of the thalamus at the only sites where neural responses could be elicited by stimulation of ipsilateral intraoral structures. The amount of thalamus and cortex given over to the ipsilateral representation in the squirrel monkey is small compared with that of the macaque monkey. This difference may be related to the lack of cheek pouches in the squirrel monkey, and therefore a different strategy for eating.The representation of the contralateral lower lip in area 3b was split by the representation of the contralateral upper lip. This split representation is in agreement with previous studies of the trigeminal representation in area 3b of the macaque monkey and may be a general feature of the representation of the trigeminal nerve in area 3b of primate cerebral cortex. © 1995 Wiley‐Liss Inc.
Overall pattern of callosal connections in visual cortex of normal and enucleated cats
Authors: Olavarria Jaime F. , Van Sluyters Richard C. 
Published: January 2005

AbstractThe effect of neonatal bilateral enucleation on the overall distribution of callosal connections in striate and extrastriate visual cortex of the cat was studied using tangential sections from the physically unfolded and flattened cortex. Callosal neurons were labeled by administering the anatomical tracer horseradish peroxidase directly to the transected corpus callosum.The pattern of callosal connections in binocularly enucleated cats showed both consistent differences and consistent similarities with the pattern in normal cats. In agreement with previous studies, it was found that callosal labeling at the 17/18 border of enucleated cats was considerably sparser than in normal cats. Moreover, we found that the strip containing the majority of labeled cells at the 17/18 border was narrower than in normal cats. In both normal and enucleated cats, scattered cells were distributed on either side of the 17/18 callosal strip, well into areas 17 and 18.In much of extrastriate cortex, the pattern of callosal connectivity in enucleated cats looked surprisingly normal. Details of the callosal pattern that were consistently found in normal cats could also be recognized in binocularly enucleated cats, such as two to four bridges of labeling spanning areas 18 and 19. Also, four zones that were free of callosal connectivity in area 7, on the banks of the suprasylvian sulcus, and in the posterior suprasylvian sulcus were found in both normal and enucleated cats. Finally, as in normal cats, dense cell labeling occurred on the crown of the suprasylvian rus at its posterior end, from which it extended laterally across both banks of the suprasylvian sulcus and into the fundus of this sulcus. The results of this study suggest that, although the stabilization of callosal connections at the 17/18 border region appears to depend on visual input, this input plays a less prominent role in the stabilization of callosal connections in extrastriate visual cortex. © 1995 Wiley‐Liss, Inc.
Axon terminals immunolabeled for dopamine or tyrosine hydroxylase synapse on GABA‐immunoreactive dendrites in rat and monkey cortex
Authors: Sesack Susan R. , Snyder Christopher L. , Lewis David A. 
Published: January 2005

AbstractDopamine afferents to the cortex regulate the excitability of pyramidal neurons via a direct synaptic input. However, it has not been established whether dopamine also modulates pyramidal cell activity indirectly through synapses on γ‐aminobutyric acid (GABA) interneurons, and whether such inputs differ across cortical regions and species. We sought to address these issues by an immunocytochemical electron microscopic approach that combined peroxidase staining for dopamine or tyrosine hydroxylase (TH) with a pre‐embedding gold‐silver marker for GABA. In the deep layers of the rat prefrontal cortex and in the superficial layers of the monkey prefrontal and primary motor cortices, terminal varicosities immunoreactive for dopamine or TH formed primarily thin, symmetric synapses on distal dendrites. Both GABA‐immunoreactive dendrites as well as unlabeled spines and dendrites were contacted by dopamine‐ or TH‐immunoteactive terminals. Synaptic specializations were detected at some, but not all of these contacts. The relative frequency of these appositional and synaptic contacts did not appear to differ between the rat and monkey prefrontal cortex, or between the monkey prefrontal and motor cortices. Across regions and species, labeled and unlabeled targets of dopamine‐ or TH‐positive terminals received additional synaptic input from unlabeled, and occasionally GABA‐immunoreactive terminals. Close appositions between dopamine‐ or TH immunoreactive and GABA‐positive terminals were observed only rarely. These findings indicate that dopamine afferents provide direct synaptic inputs to GABA local circuit neurons in a consistent fashion across cortical regions and species. Thus, dopamine's cellular actions involve direct as well as modulatory effects on both GABA interneurons and pyramidal projection neurons. © 1995 Wiley‐Liss, Inc.