bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intracellular recording and injection study of corticospinal neurons in the rat somatosensory cortex: Effect of prenatal exposure to ethanol
Authors: Miller Michael W. , Chiaia Nicholas L. , Rhoades Robert W. 
Published: January 2005

AbstractThe effects of prenatal exposure to ethanol on the structure and function of corticospinal neurons was investigated. The subjects were the 3–4‐month‐old offspring of hooded rats fed a nutritionally balanced liquid diet containing 6.7% (v/v) ethanol (Et), pair‐fed a nutritionally matched isocaloric diet (Ct), or fed chow and water (Ch). Corticospinal neurons in primary somatosensory cortex were examined by intracellularly recording and filling cells that were driven by antidromic stimulation of the pyramidal decussation.In the control rats, corticospinal neurons comprised a homogeneous morphophysiological population. Morphologically, all of the antidromically driven cells examined were pyramidal neurons with cell bodies in layer Vb. The dendrites of these neurons were spinous and branched within layers I, IV, and V. Their axons arborized within layers IV, V, and VI and some collaterals extended laterally for distances up to 2.6 mm from the cell body. The mean conduction latency was 3.6 and 3.4 msec for Ch‐ and Ct‐treated rats, respectively.In Et‐treated rats, corticospinal neurons constituted a heterogeneous population. The laminar distribution of the corticospinal neurons in Et‐treated rats was broad; the cell bodies of labeled neurons were in layers II, IV, V, and VI. The dendrites of layer Vb neurons were spinous; however, many of the spines appeared dysmorphic and the density of spines was significantly greater (32%) in Et‐treated rats than in Ct‐treated rats. Although the dendritic branching pattern for layer Vb neurons was similar to that described for the controls, a Sholl analysis showed that the complexity and extent of their dendritic trees were significantly greater in Et‐treated rats. The axons of all layer Vb neurons in Et‐treated rats had long horizontal processes that arborized in layers IV–VI, and some neurons also had an array of collaterals that ascended to layer I. The mean conduction latency for layer Vb neurons was 3.9 msec. The structure and function of ectopic neurons (those in layers II, IV, Va, Vc, and VI) in Et‐treated rats differed markedly from those of the layer Vb neurons. Morphologically, the dendritic and axonal fields of these neurons were narrower than for the layer Vb neurons, and the ectopic neurons had a mean conduction latency of 7.1 msec.The heterogeneity of the population of corticospinal neurons in Et‐treated rats may result from the effects of ethanol on early events in neuronal development such as neuronal generation and migration.
Early axon and dendritic outgrowth of spinal accessory motor neurons studied with dii in fixed tissues
Authors: Snider William D. , Palavali Vivekanand 
Published: January 2005

AbstractWe have utilized lateral diffusion of DiI in fixed tissues (Godement et al., '87: Development 101: 697–713) to study early axon and dendritic outgrowth of spinal accessory motor neurons in embryonic rats. Crystals were placed in the central canal of the cervical spinal cord near the ventral commissure in order to label growing accessory axons anterogradely and on the spinal accessory nerve to label somata and dendrites retrogradely. Animals were studied on E11–E13.We show here that it is possible to stain axonal and dendritic processes from the earliest stages of motor neuron differentiation by using DiI. Our results demonstrate that, unlike axons of other cervical motor neurons, accessory axons traverse the lateral region of the embryonic cord, which consists of neuroepithelial endfeet. Thus an affinity for neuroepithelial endfeet could partially explain their unusual intraspinal trajectory. We also show that morphology of the spinal accessory growth cones differs according to position along the accessory nerve pathway. Finally, we show that accessory motor neuron axons are in the region of their target precursors prior to the initiation of dendritic arborization. Use of DiI in fixed tissue allows study of process outgrowth in mammalian spinal cord with detail previously obtainable only in nonmammalian vertebrates.
Termination patterns of serotoninergic medullary raphespinal fibers in the rat lumbar spinal cord: An anterograde immunohistochemical study
Authors: Jones S. L. , Light A. R. 
Published: January 2005

AbstractElectrical and chemical stimulation given in the ventral medullary raphe nuclei inhibits spinal nociceptive reflexes and spinal nociceptive transmission; serotoninergic receptors have been demonstrated to partially mediate that inhibition. In the present study, the termination patterns of raphespinal fibers in the rat lumbar spinal cord demonstrating serotonin‐like immunoreactivity were examined by using the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA‐L) in combination with immunohistochemistry.Fibers and terminations from the ventral medullary raphe nuclei (raphe magnus and raphe pallidus) demonstrating both PHA‐L‐ and serotonin‐like immunoreactivity were identified in all laminae of the dorsal horn and the ventral horn. Networks of large fibers, characterized by large boutons, and which did not demonstrate serotonin‐like immunoreactivity, were identified in deeper laminae of the dorsal horn. The heterogeneous morphology of raphespinal fibers identified in the dorsal horn suggests that these fibers also may be heterogeneous in neurochemistry and function.Medial medullary sites outside the raphe nuclei were found to innervate the ventral horn and all laminae of the dorsal horn, with the exception of lamina I. Descending fibers and terminations also demonstrating serotonin‐like immunoreactivity were identified in deep laminae (III, IV, V, VI) of the dorsal horn and in the ventral horn. Similarly, large fiber networks were identified which did not demonstrate serotonin‐like immunoreactivity.
Microtubule‐associated protein 2 (MAP2) in Purkinje cell dendrites: Evidence that factors other than binding to microtubules are involved in determining its cytoplasmic distribution
Authors: Matus Andrew , Delhaye‐Bouchaud Nicole , Mariani Jean 
Published: January 2005

AbstractWe have studied the distribution of microtubule‐associated protein 2 (MAP2) in the Purkinje cell dendrites of rats whose cerebella were exposed to X‐irradiation during the second postnatal week. The Purkinje cells of such animals have abnormally elongated apical primary processes that branch in the outer molecular layer rather than close to the cell body as in normal tissue. The results show that in these distorted dendrites the MAP2 distribution is “shifted” distally relative to the normal pattern, in which MAP2 is distributed evenly throughout the dendritic tree. Tubulin and other microtubule‐associated proteins, such as MAP1, are not affected and remain evenly distributed throughout the dendritic tree despite the anatomical distortion. We conclude that the distribution of MAP2 in Purkinje cells is not determined solely by its binding to tubulin. Other factors must be involved and these appear to be related to dendritic morphology and possibly to branching.
Corticocortical connections predict patches of stimulus‐evoked metabolic activity in monkey somatosensory cortex
Authors: Juliano Sharon L. , Friedman David P. , Eslin Don E. 
Published: January 2005

AbstractStimulus‐evoked metabolic activity in the anterior parietal cortex (areas 3a, 3b, 1, and 2) occurs in the form of column‐like patches. Similar patches characterize the connections to, within, and from these fields. The relation of the patches elicited metabolically to those formed by retrograde or anterograde transport, however, is not clear. If a type of projection connecting areas 3a, 3b, 1, and 2 transmits sensory information among these cortical fields, the resultant projection pattern may directly contribute to the definition of somatosensory metabolic “columns.” To test this possibility, electrophysiological recordings in areas 3b and 1 of Macaca fascicularis monkeys characterized stimuli that elicited the best neuronal response at a specific cortical site. Iontophoretic injections of wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP) were subsequently made into the identified cortical sites. Two days later, the animals were injected with 2‐deoxyglucose (2DG) and received the somatic stimulus previously determined to best activate the neurons isolated at the injected cortical site. After injections of WGA‐HRP into physiologically defined loci in area 3b, the patches of transported label within areas 3b and 1 were colocalized with evoked metabolic activity. Injections of WGA‐HRP into area 1 produced anterogradely labeled terminals in areas 1 and 2 that also overlapped with patches of evoked metabolic activity, as did patches of retrogradely labeled cells located in area 3b. Patches of anterograde label found in area 3b after area 1 injections, however, were not coincident with the metabolically activated patches. These findings suggest that excitatory information is transmitted from area 3b to area 1 in a way that connects clusters of cells with similar response properties.
Vasopressinergic innervation of the mouse suprachiasmatic nucleus: An immuno‐electron microscopic analysis
Authors: Castel M. , Feinstein N. , Cohen S. , Harari N. 
Published: January 2005

AbstractAttempts are being made to unravel the local circuitry of the suprachiasmatic nucleus, with a view toward eventually correlating specific neuronal systems with circadian events. Hence, the vasopressinergic innervation of this nucleus in the laboratory mouse has been analyzed immunocytochemically at the light and electron microscopical levels. Monoclonal antineurophysin and polyclonal antivasopressin were used on aldehyde‐fixed brains. Serial vibratome sections of the appropriate forebrain region were prepared for pre‐embedding immunoperoxidase staining and/or postembedding immunogold labeling.Immunoreactive somata, processes, varicosities, and synaptic terminals were found throughout the suprachiasmatic nucleus, their ratio and density varying at different locations. The predominant type of vasopressinergic soma was ovoid to rounded (7–10 μm) containing secretory granules (85–120 nm), a large proportion of which were immunoreactive.Axon terminals, both nonimmunoreactive and immunoreactive, impinged upon vasopressinergic somata and processes, often displaying synaptic specializations. Vasopressinergic terminals, containing secretory granules and microvesicles, were found throughout the nucleus, particularly within the dorsomedial neuropil. These labeled terminals varied in size (0.4–3.4 μm2) and shape, ranging from compact boutons to pleomorphic profiles, some deeply indented by postsynaptic spines, either dendritic or somatic. Approximately 65% of the vasopressin‐containing terminals were axodendritic and 30% axosomatic; about 5% appeared to be axoaxonic. At least a quarter of all vasopressinergic synaptic terminals were axospinous.Other forms of interneuronal contact involving vasopressinergic elements (somata, dendrites) included extensive membrane to membrane appositional sites, and multiple puncta adhaerentia.The versatility of interconnections between vasopressin‐containing neurons in the mouse suprachiasmatic nucleus suggests a highly active and coordinated network, which contributes substantially to local intranuclear circuitry. In addition, a dense efferent vasopressinergic output is directed dorsally towards the periventricular hypothalamus, where direct associations may he established with diverse hypothalamic neuroendocrine systems.
Distribution of septohippocampal neurons containing parvalbumin or choline acetyltransferase in the rat brain
Authors: Kiss Jozsef , Patel Ambrish J. , Freund Tamas F. 
Published: January 2005

AbstractA combination of retrograde transport of horseradish peroxidase or wheat germ agglutinin‐colloidal gold with either single or double‐label immunohistochemistry is used to describe the comparative topographic distribution of parvalbumin‐ and choline acetyltransferase‐immunoreactive septal neurons that project to the hippocampal formation of the rat. The morphometric parameters of the retrogradely labelled, parvalbumin‐containing neurons were very similar, if not identical, to those neurons of the midline and medial part of the medial septum and the diagonal band regions that had previously been shown to be immunoreactive for γ‐aminobutyric acid or for glutamate decarboxylase following colchicine treatment. The total number of parvalbumin‐immunoreactive and choline acetyltransferase‐positive retrogradely labelled cells was counted at 9 representative levels through the rostrocaudal extension (from 2.4 mm anterior to the level of bregma) of the medial septal‐diagonal band complex. In the whole medial septum‐vertical limb of the diagonal band region, about 33% of the total retrogradely labelled neurons showed immunoreactivity to parvalbumin, whereas the parvalbumin‐negative cells were mainly choline acetyltransferase‐immunopositive. In comparison with the average figure, the proportion of the retrogradely labelled parvalbumin‐containing neurons was higher in the middle part (around 1.5 mm anterior to the bregma) than in either the rostral or caudal ends. The reverse was true for the distribution of the cholinergic septohippocampal neurons. At the maximum levels the parvalbumin‐immunoreactive neurons accounted for more than half of the total retrogradely labelled cells in 4 out of 6 rats. Moreover, within the complexity of the septal neurons, a marked regularity of topographic organisation was observed in the distribution of retrogradely labelled parvalbumin‐containing GABAergic and choline acetyltransferase‐positive cholinergic neurons as if they were subdivided cytoarchitectonically.
Distribution and brainstem origin of cholecystokinin‐like immunoreactivity in the opossum cerebellum
Authors: King James S. , Bishop Georgia A. 
Published: January 2005

AbstractIn order to determine the distribution of the peptide cholecystokinin (CCK) within the cerebellum and medullary precerebellar nuclei of the adult opossum, sections of these brain regions were processed for peroxidase‐antiperoxidase immunohistochemistry. Within the inferior and superior cerebellar peduncles, fine‐beaded fibers are evident and a beaded plexus of fibers is present in all the cerebellar nuclei. In the overlying cerebellar cortex, CCK‐positive mossy fiber rosettes are present in all lobules, where their morphology varies from simple enlargements to more complex rosettes. However, their distribution varies particularly in vermal lobules II, III, VII, and IX where they are organized in parasagittal bands. Climbing fibers that are positive for CCK are present in very restricted areas of vermal lobules IV, VII, and VIII. After colchicine pretreatment, CCK‐positive cell bodies are seen in restricted regions of the posterior interposed and fastigial nuclei as well as within several precerebellar nuclei known to give rise to mossy fibers. Such nuclei include the lateral cuneate nucleus, the nucleus prepositis hypoglossi, the nucleus reticularis latefalis, the nucleus raphe obscurus, the paramedian reticular nucleus, the nucleus reticularis gigantocellularis, and the medial vestibular nucleus. To localize the brainstem origin(s) of the CCK fibers in the cerebellum, a double‐label paradigm employing a retrograde tracer and CCK immunohistochemistry was used. These experiments indicate that CCK mossy fibers originate primarily within the lateral cuneate nucleus, the perihypoglossal complex, and the lateral reticular nucleus. Some also originate within the medial vestibular nucleus and the nucleus reticularis gigantocellularis. In addition, double‐labeled cell bodies are present within the caudal medial accessory inferior olive, the likely source of the CCK‐positive climbing fibers. These data indicate that specific populations of climbing fibers and mossy fibers may utilize CCK to alter the firing rate of their target neurons.
Prenatal development of retinogeniculate projections in the rabbit: An HRP study
Authors: Crabtree John W. 
Published: January 2005

AbstractThe prenatal development of the rabbit's retinal projections to the dorsal lateral geniculate nucleus (dLGN) was studied by using anterograde axonal transport of HRP injected intraocularly. Further, the ontogenesis of the dLGN's α and β sectors was studied. Fetuses aged embryonic day 18 (E18) to E29 were examined. Gestation in the rabbit is 30–31 days.On E18 the future dorsal lateral and medial geniculate nuclei appear as a continuous strip of cells along the lateral margin of the dorsal thalamus. On E21 labelled retinal fibers are invading the lateral margin of the dLGN contralateral, but not ipsilateral, to an injected eye. At this age the dorsal lateral and medial geniculate nuclei are separating. By E23 contralateral fibers occupy the entire presumptive α sector, while ipsilateral fibers are invading the caudal half of the sector, overlapping the contralateral fibers. At this age the α and β sectors begin to differentiate. On E25 contralateral fibers are more densely distributed throughout the α sector and the ipsilateral fibers are concentrated dorsally within the caudal three‐quarters of the sector. By E27 contralateral fibers begin to withdraw from a medial zone of the α sector, while ipsilateral fibers remain densest in this zone and begin to withdraw from more lateral and caudal aspects of the sector; contralateral fibers, but not ipsilateral fibers, invade the β sector. At this age the α and β sectors acquire an adult‐like appearance. By E29 the contralateral fibers vacate the β sector and the medial zone of the dLGN and the ipsilateral fibers are restricted to this zone. Thus, 1 or 2 days before birth, the locations of the ipsilateral and contralateral retinal projections to the dLGN resemble those seen in the adult.The early overlapping projections of ipsilateral and contralateral retinal fibers within the dLGN and their eventual segregation in the fetal rabbit are consistent with the development of these projections in other mammalian orders. Further, the brief invasion of the β sector by the contralateral fibers resembles the transient occupation of the carnivores' perigeniculate nucleus by developing retinal fibers. In addition, direct comparisons of temporal and spatial events during retinal innervation of the dLGN and the superior colliculus indicate several developmental differences between the two nuclei.
Neuronal connections between the cerebellar nuclei and hypothalamus in Macaca fascicularis: Cerebello‐visceral circuits
Authors: Haines D. E. , May P. J. , Dietrichs E. 
Published: January 2005

AbstractThe purpose of this study was to identify the basic pattern of interconnections between the cerebellar nuclei and hypothalamus in Macaca fascicularis. The distribution of retrogradely labeled cells and anterogradely filled cerebellofugal axons in the hypothalamus of M. fascicularis was investigated after pressure injections of a horseradish peroxidase mixture (HRP + WGA‐HRP) in the cerebellar nuclei. Following injections in the lateral, anterior, and posterior interposed cerebellar nuclei retrogradely labeled cells were present in the following areas (greatest to least concentration): lateral and dorsal hypothalamic areas, dorsomedial nucleus, griseum periventriculare hypothalami, supramammillary and tuberomammillary nuclei, posterior hypothalamic area, ventromedial nucleus and periventricular hypothalamus, around the medial mammillary nucleus, lateral mammillary nucleus, and infundibular nucleus. Cell labeling was bilateral with an ipsilateral preponderance. In these same experiments anterogradely labeled cerebellar efferent fibers terminated in the contralateral posterior, dorsal and lateral hypothalamic areas, and the dorsomedial nucleus. In these regions retrogradely labeled hypothalamic cells were occasionally found in areas that also contained anterogradely filled cerebellar axons. This suggests a partial reciprocity in this system. In addition, sparse numbers of labeled cerebellar fibers recross in the hypothalamus to distribute to homologous areas ipsilateral to the injection site. Subsequent to an injection in the medial cerebellar nucleus (NM), cell labeling was present in more rostral hypothalamic levels including the lateral and dorsal hypothalamic areas, the dorsomedial nucleus, around or in fascicles of the column of the fornix, and in the periventricular hypothalamic area. Although no fastigiohypothalamic fibers were seen in this study, on the basis of information available from the literature it is likely that such a connection exists in primates. In summary, hypothalamic projections to NM originated mainly from rostral to midhypothalamic levels, whereas those projections to the lateral three cerebellar nuclei came from mid and more caudal levels.The existence of direct hypothalamic projections to cerebellar nuclei in M. fascicularis and of cerebellofugal projection to some hypothalamic centers indicates that circuitry is present through which the cerebellum may influence visceral functions. Furthermore, the fact that projections to NM versus the other cerebellar nuclei originate from somewhat different regions of the hypothalamus would suggest that the visceral functions modulated by each pathway is not the same.
Distribution of met‐enkephalin, leu‐enkephalin, substance P, neuropeptide Y, FMRFamide, and serotonin immunoreactivities in the optic tectum of the Atlantic salmon (Salmo salar L.)
Authors: Vecino Elena , Ekström Peter 
Published: January 2005

AbstractThe distribution of the neuropeptides methionine‐ and leucine‐enkephalins, substance P, FMRFamide, neuropeptide Y, and vasoactive intestinal peptide, as well as the biogenic amine serotonin was studied in the optic tectum of the Atlantic salmon by means of immunocytochemistry. Peroxidase‐antiperoxidase and indirect immunofluorescence methods were used to compare the differential laminar distribution of each of these substances. Nine parts of the optic tectum were selected for analysis on frontal sections: median, dorsolateral, and ventrolateral areas at rostral, medial, and caudal levels.Methionine‐ and leucine‐enkephalin immunoreactive fibers were found in discrete sublayers in the following strata: stratum opticum, stratum fibrosum et griseum superficiale, stratum griseum centrale, stratum, and album centrale. Most of the substance P‐, serotonin‐, and vasoactive intestinal peptide‐immunoreactive fibers were found in the stratum album centrale, whereas the FMRFamide‐ and neuropeptide Y‐immunoreactive fibers were more or less randomly distributed within most of the strata of the optic tectum. Neuropeptide Y‐immunoreactive cell bodies were located in the stratum periventriculare.We suggest an extrinsic origin for most of the immunoreactive fibers observed in the optic tectum, except for the neuropeptide Y‐immunoreactive fibers that probably originate in the periventricular neurons. Although retinal peptidergic input to the optic tectum has been proposed in other vertebrates, there is no evidence that any of the neuropeptidelike or serotonin immunoreactive fibers in the optic tectum of the salmon should be of retinal origin. Differences and similarities with the distribution of neuropeptides in the optic tectum in representatives of other vertebrate classes are discussed.