bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modulation of responses of feline ventral spinocerebellar tract neurons by monoamines
Authors: Hammar Ingela , Chojnicka Barbara , Jankowska Elzbieta 
Published: August 2002

AbstractVentral spinocerebellar tract neurons located in laminae V–VII of cat lumbar spinal cord were tested for the effects of ionophoretically applied monoamines and receptor selective agonists. Extracellularly recorded responses, monosynaptically evoked by group I afferents in a muscle nerve, were compared before, during, and after ionophoresis. They were analyzed with respect to changes in the number of evoked spikes and in the latency. Both serotonin (5‐HT) and noradrenaline (NA) were found to facilitate responses of all neurons tested. Ionophoresis of three serotonin subtype receptor agonists (5‐carboxamidotryptamine maleate, 5 methoxytryptamine HCl, and alpha‐methyl 5‐hydroxytryptamine) and of two NA receptor agonists (phenylephrine and isoproterenol) likewise had a facilitatory effect. However, three other 5‐HT receptor agonists (8‐hydroxy‐dipropylaminotetraline hydrobromide), 2‐methyl 5‐hydroxytryptamine, and 1‐(2,5‐dimethoxy‐4‐iodophenyl)‐2‐aminopropane HCl and two NA receptor agonists (tizanidine and clonidine) had the opposite effect because they depressed responses of the tested neurons. These results show that information forwarded by means of the ventral spinocerebellar tract may be modulated by monoamines and that several receptor subtypes, located pre‐ or postsynaptically, may be involved. The results also demonstrate that transmission by means of group I muscle afferents may not only be facilitated by monoamines but also depressed by selective receptor subtype activation. J. Comp. Neurol. 443:298–309, 2002. © 2002 Wiley‐Liss, Inc.
Axon arbors and synaptic connections of a vulnerable population of interneurons in the dentate gyrus in vivo
Authors: Buckmaster Paul S. , Yamawaki Ruth , Zhang Guo Feng 
Published: August 2002

AbstractThe predominant γ‐aminobutyric acid (GABA)ergic neuron class in the hilus of the dentate gyrus consists of spiny somatostatinergic interneurons. We examined the axon projections and synaptic connections made by spiny hilar interneurons labeled with biocytin in gerbils in vivo. Axon length was 152–497 mm/neuron. Sixty to 85% of the axon concentrated in the outer two thirds of the molecular layer of the dentate gyrus. The septotemporal span of the axon arbor extended over 48–82% of the total hippocampal length, which far exceeds the septotemporal span of axons of granule cells whose complete axon arbors extended over 15–29%. A three‐dimensionally reconstructed 216‐μm‐long spiny hilar interneuron axon segment in the outer third of the molecular layer formed an average of 1 synapse every 5.1 μm. Of the 42 symmetric (inhibitory) synapses formed by the reconstructed segment, 88% were with spiny dendrites of presumed granule cells, and 67% were with dendritic spines that also receive an asymmetric (excitatory) contact from an unlabeled axon terminal. Postembedding GABA‐immunocytochemistry revealed that 55% of the GABAergic synapses in the outer third of the molecular layer were with spines. Therefore, in the outer molecular layer, spiny hilar interneurons form synaptic contacts that appear to be positioned to exert inhibitory control near sites of excitatory synaptic input from the entorhinal cortex to granule cell dendritic spines. These findings demonstrate far‐reaching, yet highly specific, connectivity of individual interneurons and suggest that the loss of spiny hilar interneurons, as occurs in temporal lobe epilepsy, may contribute to hyperexcitability in the hippocampus. J. Comp. Neurol. 445:360–373, 2002. © 2002 Wiley‐Liss, Inc.
Brainstem projections to midline and intralaminar thalamic nuclei of the rat
Authors: Krout Karl E. , Belzer Rebecca E. , Loewy Arthur D. 
Published: August 2002

AbstractThe projections from the brainstem to the midline and intralaminar thalamic nuclei were examined in the rat. Stereotaxic injections of the retrograde tracer cholera toxin β ‐subunit (CTb) were made in each of the intralaminar nuclei of the dorsal thalamus: the lateral parafascicular, medial parafascicular, central lateral, paracentral, oval paracentral, and central medial nuclei; in the midline thalamic nuclei—the paraventricular, intermediodorsal, mediodorsal, paratenial, rhomboid, reuniens, and submedius nuclei; and, in the anteroventral, parvicellular part of the ventral posterior, and caudal ventral medial nuclei. The retrograde cell body labeling pattern within the brainstem nuclei was then analyzed. Nearly every thalamic site received a projection from the deep mesencephalic reticular, pedunculopontine tegmental, dorsal raphe, median raphe, laterodorsal tegmental, and locus coeruleus nuclei. Most intralaminar thalamic sites were also innervated by unique combinations of medullary and pontine reticular formation nuclei such as the subnucleus reticularis dorsalis, gigantocellular, dorsal paragigantocellular, lateral, parvicellular, caudal pontine, ventral pontine, and oral pontine reticular nuclei; the dorsomedial tegmental, subpeduncular tegmental, and ventral tegmental areas; and, the central tegmental field. In addition, most intralaminar injections resulted in retrograde cell body labeling in the substantia nigra, nucleus Darkschewitsch, interstitial nucleus of Cajal, and cuneiform nucleus. Details concerning the pathways from the spinal trigeminal, nucleus tractus solitarius, raphe magnus, raphe pallidus, and the rostral and caudal linear raphe nuclei to subsets of midline and intralaminar thalamic sites are discussed in the text. The discussion focuses on brainstem‐thalamic pathways that are likely involved in arousal, somatosensory, and visceral functions. J. Comp. Neurol. 448:53–101, 2002. © 2002 Wiley‐Liss, Inc.
Combination of gonadal steroid treatment and peripheral nerve grafting results in a peripheral motoneuron‐like pattern of BII‐tubulin mRNA expression in axotomized hamster rubrospinal motoneurons
Authors: Storer Paul D. , Houle John D. , Oblinger Monica , Jones Kathryn J. 
Published: August 2002

AbstractRubrospinal motoneurons (RSMN) represent a population of androgen receptor‐containing central motoneurons in rodents. In this study, the ability of testosterone propionate (TP), alone or in conjunction with a peripheral nerve graft (PNG), to alter the molecular program of injured RSMN was accomplished using βII‐tubulin cDNA probes and quantitative in situ hybridization (ISH). Initial fluoro‐gold labeling experiments following a T1 hemisection established that, as in the rat, the hamster rubrospinal system is essentially crossed and that injured RSMN concentrate in the ventrolateral region of the red nucleus. In the second experimental series, adult gonadectomized male hamsters were subjected to a right T1 hemisection, with half of the operated animals immediately subcutaneously implanted with 1 10 mm TP Silastic capsule and the other half sham implanted. In a third experimental series, animals were subjected to T1 hemisection, followed by transplantation of a predegenerated autologous segment of peripheral nerve. Half of the animals in each group received TP implants at the time of spinal cord injury and PNG. Postoperative times were 2, 7, and 14 days (dpo). Quantitative ISH was performed using a βII‐tubulin‐specific 33P‐labeled cDNA probe, emulsion autoradiography, and computerized image analysis for grain counting. Injury alone resulted in a short‐lived increase in βII‐tubulin mRNA expression in the RSMN at 2 dpo, with a significant decline to well below control values at 7 and 14 dpo. TP treatment or PNG alone attenuated, but did not prevent, the down‐regulation of βII‐tubulin mRNA. In contrast, the combination of TP with a PNG sustained the injury‐induced increase in βII‐tubulin mRNA levels throughout the postoperative period of 2, 7, and 14 dpo. The synergistic effects of the two treatment strategies confirm the importance of targeting multiple aspects of the injury response for therapeutic intervention. J. Comp. Neurol. 449:364–373, 2002. © 2002 Wiley‐Liss, Inc.
Evidence for regional heterogeneity in corticotropin‐releasing factor interactions in the dorsal raphe nucleus
Authors: Valentino Rita J. , Liouterman Larisa , Van Bockstaele Elisabeth J. 
Published: August 2002

AbstractThe dorsal raphe nucleus (DR) is innervated by fibers containing the stress‐related neurohormone corticotropin‐releasing factor (CRF), which alters DR neuronal activity and serotonin release in rats. This study examined the relative distribution of CRF‐immunoreactive fibers in the rat DR by using light level densitometry. Additionally, CRF‐immunoreactive processes within specific subregions of the DR were examined at the ultrastructural level by using electron microscopy. CRF‐immunoreactive fibers were organized within the DR along a caudal‐rostral gradient, such that proceeding rostrally, innervation shifted from dorsolateral to ventromedial. Numerous CRF‐immunoreactive axon terminals containing dense‐core vesicles were found in both the caudal dorsolateral region and the rostral ventromedial/interfascicular region. These formed synaptic specializations with unlabeled dendrites and frequently contacted nonlabeled axon terminals. Semiquantitative analysis revealed certain differences between the two regions with respect to the types of associations made by CRF‐immunoreactive terminals. Associations with dendrites were more frequent in the dorsolateral vs. ventromedial region (65% of 171 terminals vs. 39% of 233 terminals, respectively), whereas associations with axon terminals were more frequent in the ventromedial/interfascicular vs. the dorsolateral region (72% of 233 terminals vs. 57% of 171 terminals, respectively). Additionally, synaptic specializations between CRF‐immunoreactive terminals and dendrites were more frequently asymmetric in the dorsolateral region (60%) and symmetric (49%) in the ventromedial/interfascicular region. Regional differences in CRF terminal interactions in the DR could account for the reported heterogeneous effects of CRF on DR neuronal activity and forebrain serotonin release. Importantly, the present results provide anatomical substrates for regulation of the DR by endogenous CRF. J. Comp. Neurol. 435:450–463, 2001. © 2001 Wiley‐Liss, Inc.
μ‐opioid receptors are present in functionally identified sympathoexcitatory neurons in the rat rostral ventrolateral medulla
Authors: Aicher Sue A. , Schreihofer Ann M. , Kraus James A. , Sharma Sarita , Milner Teresa A. , Guyenet Patrice G. 
Published: August 2002

AbstractAgonists of the μ‐opioid receptor (MOR) produce profound hypotension and sympathoinhibition when microinjected into the rostral ventrolateral medulla (RVL). These effects are likely to be mediated by the inhibition of adrenergic and other presympathetic vasomotor neurons located in the RVL. The present ultrastructural studies were designed to determine whether these vasomotor neurons, or their afferents, contain MORs. RVL bulbospinal barosensitive neurons were recorded in anesthetized rats and filled individually with biotinamide by using a juxtacellular labeling method. Biotinamide was visualized by using a peroxidase method and MOR was identified by using immunogold localization of an antipeptide antibody that recognizes the cloned MOR, MOR1. The subcellular relationship of MOR1 to RVL neurons with fast‐ or slow‐conducting spinal axons was examined by electron microscopy. Fast‐ and slow‐conducting cells were not morphologically distinguishable. Immunogold‐labeling for MOR1 was found in all RVL bulbospinal barosensitive neurons examined (9 of 9). MOR1 was present in 52% of the dendrites from both types of cells and in approximately half of these dendrites the MOR1 was at nonsynaptic plasmalemmal sites. A smaller portion of biotinamide‐labeled dendrites (16%) from both types of cells were contacted by MOR1‐containing axons or axon terminals. Together, these results suggest that MOR agonists can directly influence the activity of all types of RVL sympathoexcitatory neurons and that MOR agonists may also influence the activity of afferent inputs to these cells. The heterogenous distribution of MORs within individual RVL neurons indicates that the receptor is selectively targeted to specific pre‐ and postsynaptic sites. J. Comp. Neurol. 433:34–47, 2001. © 2001 Wiley‐Liss, Inc.
Regenerating descending axons preferentially reroute to the gray matter in the presence of a general macrophage/microglial reaction caudal to a spinal transection in adult zebrafish
Authors: Becker Thomas , Becker Catherina G. 
Published: August 2002

AbstractWe analyzed pathway choices of regenerating, mostly supraspinal, descending axons in the spinal cord of adult zebrafish and the cellular changes in the spinal cord caudal to a lesion site after complete spinal transection. Anterograde tracing (by application of the tracer rostral to the spinal lesion site) showed that significantly more descending axons (74%) regenerated in the spinal gray matter of the caudal spinal cord than would be expected from random growth. Retrograde tracing (by application of the tracer caudal to the spinal lesion site) showed that, rostral to the lesion, most of these axons (80%) extended into the major white matter tracts. Thus, ventral descending tracts often were devoid of labeled axons caudal to a spinal lesion but contained many axons rostral to the lesion in the same animals, indicating a pathway switch of descending axons from the white matter to the gray matter. Ascending axons of spinal neurons were not observed regrowing to the rostral tracer application site; therefore, they most likely did not contribute to the axonal populations analyzed. A macrophage/microglia response within 2 days of spinal cord transection, along with phagocytosis of myelin, was observed caudal to the transection by immunohistochemistry and electron microscopy. Nevertheless, caudal to the lesion, descending tracts in the white matter were filled with myelin debris during the time of axonal regrowth, at least up to 6 weeks postlesion. We suggest that the spontaneous regeneration of axons of supraspinal origin after spinal cord transection in adult zebrafish may be due in part to the axons' ability to negotiate novel pathways in the spinal cord gray matter. J. Comp. Neurol. 433:131–147, 2001. © 2001 Wiley‐Liss, Inc.
Subcellular localization of α‐2A‐adrenergic receptors in the rat medial nucleus tractus solitarius: Regional targeting and relationship with catecholamine neurons
Authors: Glass Michael J. , Huang Jie , Aicher Sue A. , Milner Teresa A. , Pickel Virginia M. 
Published: August 2002

Abstractα‐2A‐adrenergic receptor (α2A‐AR) agonists modulate diverse autonomic functions. These actions are believed to involve functionally specialized, second‐order neurons in catecholamine‐containing portions of the medial nucleus tractus solitarius (mNTS) at both intermediate (NTSi) and caudal (NTSc) levels. However, the cellular mechanisms subserving α2A‐AR‐mediated actions within the mNTS have yet to be established. Immunocytochemistry was employed to examine the subcellular distribution of α2A‐AR in both the intermediate and caudal mNTS and its association with cells containing the catecholamine‐synthesizing enzyme tyrosine hydroxylase (TH). Quantitative regional comparison using immunogold showed that this receptor was distributed differentially to dendrites (NTSi, 46%; NTSc, 31%) and glia (NTSi, 29%; NTSc, 48%) at different levels of the NTS. Somata, axons, and terminals less frequently contained α2A‐AR. The subcellular distribution of α2A‐AR relative to catecholaminergic neurons also was similar within both subregions. Approximately 50% of α2A‐AR‐labeled somata also contained TH. In somatic profiles, α2A‐AR labeling was often found in the cytosol and in association with endoplasmic reticulum and Golgi complexes, sites of receptor synthesis and trafficking. Approximately 20% of α2A‐AR‐immunoreactive dendrites also contained TH, where the receptor was often found on extrasynaptic portions of the plasma membrane near unlabeled terminals, some of which made symmetric contacts. However, TH‐labeled terminals and dendrites usually were detected in the neuropil at a short distance (<10 μm) from α2A‐AR‐labeled neurons. α2A‐AR‐labeled glia frequently apposed unlabeled dendrites and terminals and were often located near TH‐immunoreactive dendrites. These results indicate that, within the mNTS, α2A‐AR is involved in a variety of autonomic processes, including postsynaptic modulation of mostly noncatecholaminergic dendrites, as well as influencing glia functions. J. Comp. Neurol. 433:193–207, 2001. © 2001 Wiley‐Liss, Inc.
Expression of the melanin‐concentrating hormone (MCH) receptor mRNA in the rat brain
Authors: Saito Yumiko , Cheng Michelle , Leslie Frances M. , Civelli Olivier 
Published: August 2002

AbstractThe melanin‐concentrating hormone (MCH) system is thought to be an important regulator of food intake. Recently the orphan G protein‐coupled receptor SLC‐1 was identified as the MCH receptor (MCHR). Preliminary analyses of MCHR mRNA distribution have supported a role for the MCH system in nutritional homeostasis. We report here a complete anatomical distribution of the MCHR mRNA. We have found high levels of expression of MCHR mRNA in most anatomical areas implicated in control of olfaction, with the exception of the main olfactory bulb. Dense labeling was also detected in the hippocampal formation, subiculum, and basolateral amygdala, all of which are important in learning and memory, and in the shell of the nucleus accumbens, a substrate for motivated behavior and feeding. Within the hypothalamus, MCHR mRNA was moderately expressed in the ventromedial nucleus, arcuate nucleus, and zona incerta, all of which serve key roles in the neuronal circuitry of feeding. In the brainstem, strong expression was observed in the locus coeruleus, which is implicated in arousal, as well as in nuclei that contribute to orofacial function and mastication, including the facial, hypoglossal, motor trigeminal, and dorsal motor vagus nuclei. In most regions there was a good correspondence between MCHR mRNA distribution and that of MCH‐immunoreactive fibers. Taken together, these data suggest that MCH may act at various levels of the brain to integrate various aspects of feeding behavior. However, the extensive MCHR distribution throughout the brain suggests that this receptor may play a role in other functions, most notably reinforcement, arousal, sensorimotor integration, and autonomic control. J. Comp. Neurol. 435:26–40, 2001. © 2001 Wiley‐Liss, Inc.
Borders and cytoarchitecture of the perirhinal and postrhinal cortices in the rat
Authors: Burwell Rebecca D. 
Published: August 2002

AbstractCytoarchitectonic and histochemical analyses were carried out for perirhinal areas 35 and 36 and the postrhinal cortex, providing the first detailed cytoarchitectonic study of these regions in the rat brain. The rostral perirhinal border with insular cortex is at the extreme caudal limit of the claustrum, consistent with classical definitions of insular cortex dating back to Rose ([1928] J. Psychol. Neurol. 37:467–624). The border between the perirhinal and postrhinal cortices is at the caudal limit of the angular bundle, as previously proposed by Burwell et al. ([1995] Hippocampus 5:390–408). The ventral borders with entorhinal cortex are consistent with the Insausti et al. ([1997] Hippocampus 7:146–183) description of that region and the Dolorfo and Amaral ([1998] J. Comp. Neurol. 398:25–48) connectional findings. Regarding the remaining borders, both the perirhinal and postrhinal cortices encroach upon temporal cortical regions as defined by others (e.g., Zilles [1990] The cerebral cortex of the rat, p 77–112; Paxinos and Watson [1998] The rat brain in stereotaxic coordinates). Based on cytoarchitectonic and histochemical criteria, perirhinal areas 35 and 36 and the postrhinal cortex were further subdivided. Area 36 was parceled into three subregions, areas 36d, 36v, and 36p. Area 35 was parceled into two cytoarchitectonically distinctive subregions, areas 35d and 35v. The postrhinal cortex was divided into two subregions, areas PORd and PORv. These regional definitions of perirhinal areas 35 and 36 and the postrhinal cortex were confirmed by new empirical analyses of previously reported quantitative connectional data (Burwell and Amaral [1998a] J. Comp. Neurol. 398:179–205). J. Comp. Neurol. 437:17–41, 2001. © 2001 Wiley‐Liss, Inc.
Localization of two high‐threshold potassium channel subunits in the rat central auditory system
Authors: Li Wenge , Kaczmarek Leonard K. , Perney Teresa M. 
Published: August 2002

AbstractThe firing pattern of auditory neurons is determined in part by the type of voltage‐sensitive potassium channels expressed. The expression patterns for two high‐threshold potassium channels, Kv3.1 and Kv3.3, that differ in inactivation properties were examined in the rat auditory system. The positive activation voltage and rapid deactivation kinetics of these channels provide rapid repolarization of action potentials with little effect on action potential threshold. In situ hybridization experiments showed that Kv3.3 mRNA was highly expressed in most auditory neurons in the rat brainstem, whereas Kv3.1 was expressed in a more limited population of auditory neurons. Notably, Kv3.1 mRNA was not expressed in neurons of the medial and lateral superior olive and a subpopulation of neurons in the ventral nucleus of the lateral lemniscus. These results suggest that Kv3.3 channels may be the dominant Kv3 subfamily member expressed in brainstem auditory neurons and that, in some auditory neurons, Kv3.1 and Kv3.3 may coassemble to form functional channels. The localization of Kv3.1 protein was examined immunohistochemically. The distribution of stained somata and neuropil varied across auditory nuclei and correlated with the distribution of Kv3.1 mRNA‐expressing neurons and their terminal arborizations, respectively. The intensity of Kv3.1 immunoreactivity varied across the tonotopic map in the medial nucleus of the trapezoid body with neurons responding best to high‐frequency tones most intensely labeled. Thus, auditory neurons may vary the types and amount of K+ channel expression in response to synaptic input to subtly tune their firing properties. J. Comp. Neurol. 437:196–218, 2001. © 2001 Wiley‐Liss, Inc.
GABA‐immunoreactive neurons in the mushroom bodies of the honeybee: An electron microscopic study
Authors: Ganeshina Olga , Menzel Randolf 
Published: August 2002

AbstractSynaptic contacts of γ‐aminobutyric acid (GABA) ‐immunoreactive neurons in honeybee mushroom bodies were studied by using electron microscopic immunocytochemistry. In the lip region of the calyx neuropil, GABA‐immunoreactive profiles formed synapses onto both small postsynaptic profiles (76%) and large immunonegative boutons (4%), which were likely to belong to the intrinsic and extrinsic mushroom body neurons, respectively. Three morphologic types of the large immunonegative boutons were distinguished: “light,” “dark,” and “dense core”; all of them received synaptic inputs from the GABA‐immunoreactive profiles. A significant proportion of the synapses formed by the GABA‐immunoreactive neurons in the lip region (20%) were input synapses from immunonegative neurons. Analysis of thin serial sections showed that the output and input synapses formed microcircuits in which both large immunonegative boutons and small postsynaptic profiles were involved. We interpret these findings to show that negative feedforward and feedback loops exist within the microcircuits of the lip region. J. Comp. Neurol. 437:335–349, 2001. © 2001 Wiley‐Liss, Inc.