bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology and connections of the abdominal accessory neurons of the crayfish Cherax destructor
Authors: Drummond Joanne M. , Macmillan David L. 
Published: January 2004

AbstractAssociated with the abdominal muscle receptor organs of crayfish are accessory neurons that inhibit the activity of the stretch receptors. Cobalt infusion into their cut axons reveals four accessory somata associated with each hemiganglion in the abdomen of the crayfish Cherax destructor. These conform to the pattern described previously for these neurons: The cell bodies are in the ganglion posterior to the one from which they exit. We recorded intracellularly from the largest accessory neurons, Acc‐1 and Acc‐2, and stained them with intracellular dye to establish unambiguously the characteristics defining their identity and structure. We describe their branching patterns in the ganglion of origin and the ganglion of exit. This morphological information permitted us to distinguish all four accessory neurons in preparations with dye infused through their cut axons, and we propose a revised, unambiguous nomenclature for the two smaller ones. Our intracelluar recordings allowed us to reexamine the physiological relationships of Acc‐1 and Acc‐2, the only accessory neurons for which there are data in the literature. In general, the connections and inputs described in previous studies were substantiated, although there has clearly been confusion between the two, and they differ in a number of significant ways. We found that they are seldom active together, have different firing patterns, and may operate with different clusters of extensor and flexor motorneurons. The results illustrate the level at which the accessory neurons operate within the abdominal control system but do not distinguish between competing hypotheses concerning their role in behavior. The data are consistent with the view that accessory neurons assist in timing between adjacent segments. J. Comp. Neurol. 469:548–558, 2004. © 2004 Wiley‐Liss, Inc.
Presynaptic N‐methyl‐D‐aspartate receptor expression is increased by estrogen in an aromatase‐rich area of the songbird hippocampus
Authors: Saldanha Colin J. , Schlinger Barney A. , Micevych Paul E. , Horvath Tamas L. 
Published: January 2004

AbstractThe vertebrate hippocampus (HP) is sensitive to estrogens, in part via effects on N‐methyl‐D‐aspartate (NMDA)‐type glutamate receptors (NR). Although the precise mechanism of this interaction is unclear, it constitutes a key interface in the plasticity of the adult vertebrate HP. The songbird HP expresses high levels of aromatase (estrogen synthase), suggesting that locally generated steroid may affect excitatory pathways. By using light, confocal, and electron microscopy with antibodies that specifically recognize aromatase and NR, we have 1) mapped their distribution in the zebra finch brain, 2) documented their coexpression in HP neurons, 3) studied the ultrastructure of NR‐expressing cells in the HP, and 4) tested the influence of estrogen on the cellular and subcellular characteristics of NR‐positive HP neurons. Aromatase and NR are coexpressed in HP neurons. NRs are detectable in presynaptic boutons of the songbird HP in addition to postsynaptic loci. Treatment with estrogen increased the somal size and innervation of NR‐positive neurons and the frequency of presynaptic NR. Autoreception of excitatory neurotransmission via presynaptic NR may promote the strengthening of activity‐dependent, excitatory synapses, thereby enhancing learning. NR‐mediated autoreception may underlie estrogenic enhancement of HP structural and functional plasticity. J. Comp. Neurol. 469:522–534, 2004. © 2004 Wiley‐Liss, Inc.
Activity‐dependent regulation of the potassium channel subunits Kv1.1 and Kv3.1
Authors: Lu Yong , Monsivais Pablo , Tempel Bruce L. , Rubel Edwin W 
Published: January 2004

AbstractAfferent activity, especially in young animals, can have profound influences on postsynaptic neuronal structure, function and metabolic processes. Most studies evaluating activity regulation of cellular components have examined the expression of ubiquitous cellular proteins as opposed to molecules that are specialized in the neurons of interest. Here we consider the regulation of two proteins (voltage‐gated potassium channel subunits Kv1.1 and Kv3.1) that auditory brainstem neurons in birds and mammals express at uniquely high levels. Unilateral removal of the avian cochlea leads to rapid and dramatic reduction in the expression of both proteins in the nucleus magnocellularis (NM; a division of the avian cochlear nucleus) neurons as detected by immunocytochemistry. Uniform downregulation of Kv1.1 was reliable by 3 hours after cochlea removal, was sustained through 96 hours, and returned to control levels in the surviving neurons by 2 weeks. The activity‐dependent changes in Kv3.1 appear to be bimodal and are more transient, being observed at 3 hours after cochlea removal and recovering to control levels within 24 hours. We also explored the functional properties of Kv1.1 in NM neurons deprived of auditory input for 24 hours by whole‐cell recordings. Low‐threshold potassium currents in deprived NM neurons were not significantly different from control neurons in their amplitude or sensitivity to dendrotoxin‐I, a selective K+ channel antagonist. We conclude that the highly specialized abundant expression of Kv1.1 and 3.1 channel subunits is not permanently regulated by synaptic activity and that changes in overall protein levels do not predict membrane pools. J. Comp. Neurol. 470:93–106, 2004. © 2004 Wiley‐Liss, Inc.
Alterations in calretinin immunostaining in the ferret superior olivary complex after cochlear ablation
Authors: Alvarado Juan Carlos , Fuentes‐Santamaria Verónica , Henkel Craig K. , Brunso‐Bechtold Judy K. 
Published: January 2004

AbstractIn this study, we used image analysis to assess changes in calretinin immunoreactivity in the lateral (LSO) and medial (MSO) superior olivary nuclei in ferrets 2 months after unilateral cochlear ablations at 30–40 days of age, soon after hearing onset. These two nuclei are the first significant sites of binaural convergence in the ascending auditory system, and both receive direct projections from the deafferented cochlear nucleus. Cochlear ablation results in a decrease in the overall level of calretinin immunostaining within the LSO ipsilaterally compared with the contralateral side and with control animals and within the MSO bilaterally compared with control ferrets. In addition, the level of calretinin immunostaining ipsilaterally within neurons in the LSO was significantly less in cochlear ablated than control animals. In contrast, there was no effect of cochlear ablation on the level of calretinin immunostaining within neurons either in the contralateral LSO or in the MSO. These results are consistent with a downregulation in calretinin within the neuropil of MSO bilaterally and LSO ipsilaterally, as well as a downregulation in calretinin within somata in the ipsilateral LSO as a result of unilateral cochlear ablation soon after hearing onset. Thus, cochlear‐driven activity appears to affect calcium binding protein levels in both neuropil and neurons within the superior olivary complex. J. Comp. Neurol. 470:63–79, 2004. © 2004 Wiley‐Liss, Inc.
Response of olfactory ensheathing cells to the degeneration and regeneration of the peripheral olfactory system and the involvement of the neuregulins
Authors: Williams Sarah K. , Franklin Robin J.M. , Barnett Susan C. 
Published: January 2004

AbstractIn this study we examined the proliferative response of olfactory ensheathing cells (OECs) to olfactory receptor neuron injury induced by zinc sulfate (ZnSO4) irrigation and related the response of OECs within the peripheral system to the inflammatory response induced by injury and the expression profile of neuregulins. After ZnSO4 treatment, degeneration in the epithelium is reproducible and rapid, with regeneration following after 4 days, and is morphologically complete by 5 weeks. Changes in the olfactory bulb are less dramatic, although degeneration of both the outer and the glomerular layers occurred. Treatment also induced a marked inflammatory response in both the epithelium and the bulb. Unlike Schwann cell changes associated with Wallerian degeneration, OECs did not proliferate or obviously migrate within the olfactory system in response to axonal loss, suggesting that the new nerves generated from the epithelium regrow back through conduits already formed by the glia. Expression of neuregulin 1α was maintained in the nerve by OECs, and changes in neuregulin 1 mRNA and erbB2 mRNA expression were detected, indicating that these growth factors may play a role in the regeneration of the peripheral olfactory system but not in OEC proliferation. J. Comp. Neurol. 470:50–62, 2004. © 2004 Wiley‐Liss, Inc.
Characterization of neuropeptide Y Y2 and Y5 receptor expression in the mouse hypothalamus
Authors: Fetissov Sergueï O. , Byrne Leah C. , Hassani Hessameh , Ernfors Patrik , Hökfelt Tomas 
Published: January 2004

AbstractNeuropeptide Y (NPY) neurons abundantly innervate the hypothalamus, where NPY is involved in the regulation of a broad range of homeostatic functions. In the present work we studied NPY Y2 and Y5 receptor (R) gene expression in the mouse hypothalamus by using immunohistochemical detection of β‐galactosidase (β‐gal), a gene reporter molecule for Y2R and Y5R in Y2R‐knockout (KO) and Y5R‐KO mice, respectively. With this approach, cells normally expressing Y2R or Y5R are immunopositive for β‐gal. In the hypothalamus of the Y2R‐KO mouse, β‐gal immunoreactivity (‐ir) was found in numerous neurons of the medial preoptic nucleus as well as in the lateral anterior, periventricular, dorsomedial, tuberal, perifornical, and arcuate nuclei. Most of the dopaminergic neurons in the A13 dorsal hypothalamic group were β‐gal positive, whereas other hypothalamic dopaminergic neurons rarely displayed β‐gal‐ir. In the arcuate nucleus, most of the β‐gal‐positive neurons expressed NPY, but colocalizations with β‐endorphin were also found; in the tuberal and perifornical nuclei, many β‐gal‐positive neurons contained nitric oxide synthase. β‐Gal‐ir was also found in other forebrain regions of the Y2R‐KO mouse, including the amygdala, thalamic nuclei, hippocampal CA3 area, and cortex. In the hypothalamus of the Y5R‐KO mouse, β‐gal‐positive neurons were found mainly in the arcuate nucleus and contained β‐endorphin. The present data show that Y2R and Y5R are expressed in distinct groups of hypothalamic neurons. High levels of Y2R expression in the preoptic nuclei suggest an involvement of Y2R in the regulation of reproductive behavior, whereas Y2R expression in the arcuate, dorsomedial, and perifornical nuclei may be relevant to feeding and body weight control. The finding that A13 dopaminergic neurons express Y2R suggests a new mechanism putatively involved in the central control of feeding, in which NPY can modulate dopamine secretion. The distribution of Y5R expression supports earlier evidence for involvement of this receptor in control of feeding and body weight via NPY's action on proopiomelanocortin‐expressing neurons. J. Comp. Neurol. 470:256–265, 2004. © 2004 Wiley‐Liss, Inc.
Fos expression in otolith‐related brainstem neurons of postnatal rats following off‐vertical axis rotation
Authors: Lai Chun‐Hong , Tse Yiu‐Chung , Shum Daisy K.Y. , Yung Ken K.L. , Chan Ying‐Shing 
Published: January 2004

AbstractTo determine the critical time of responsiveness of developing otolith organ‐related brainstem neurons and their distribution, Fos protein expression in response to off‐vertical axis rotations (OVAR) was mapped in conscious Sprague Dawley rats from P5 to adulthood. OVAR was used to activate sequentially all utricular hair cells per 360° revolution. We detected the coding of horizontal head positions in otolith organ‐related neurons within the vestibular nucleus as early as P7. In the vestibular nuclear complex and its subgroups, the density of Fos‐immunoreactive (Fos‐ir) neurons increased steadily with age and reached the adult level by P21. In both labyrinthectomized rats subjected to OVAR and normal rats kept stationary, labeled neurons were found sporadically in the aforementioned brain regions in each age group, confirming that Fos labeling observed in neurons of normal experimental rats subjected to OVAR was due to otolith organ stimulation. Whereas OVAR‐induced Fos‐ir neurons were also first observed in vestibular‐related brain areas, such as the prepositus hypoglossal nucleus, gigantocellular reticular nucleus, and locus coeruleus, of normal experimental rats at P7, those in the inferior olive were observed only from P14 onward. This indicates the unique maturation time of inferior olivary neurons in gravity‐related spatial coding. In general, age‐dependent increase in OVAR‐induced Fos‐ir neurons was observed in brain areas that received otolith inputs. The locus coeruleus was exceptional in that prominent OVAR‐induced Fos‐ir neuronal number did not change with maturation, and this was well above the low but significant number of Fos‐ir neurons in control preparations. Taken together, our results suggest that neuronal subpopulations within the developing network of the horizontal otolith system provide an anatomical basis for the postnatal development of otolith organ‐related sensorimotor functions. J. Comp. Neurol. 470:282–296, 2004. © 2004 Wiley‐Liss, Inc.
In vitro analysis of mechanisms underlying age‐dependent failure of axon regeneration
Authors: Hafidi Aziz , Grumet Martin , Sanes Dan H. 
Published: January 2004

AbstractSevered axons of the inferior colliculus (IC) commissure can regenerate across a lesion in organotypic cultures from postnatal day (P) 6 gerbils, but this regenerative capacity is lost by P12 (Hafidi et al. [ 1995] J Neurosci 15:1298–1307, [1999] J Neurobiol 41:267–280). In the present study, we examined the mechanisms underlying this age‐dependent failure of axons to regenerate. In P6–P12 heterochronic cultures, the P12 axons failed to cross the lesion site and project to the contralateral P6 IC lobe. In contrast, axons originating from the P6 lobe could regenerate through the lesion and invade the contralateral P12 IC lobe. To determine whether this age‐dependent change in regenerative capacity can develop in organotypic cultures, IC slices with an intact commissure were obtained from P6 animals, grown in vitro for 6 days, and then lesioned at the commissure. In these slices, axon regeneration failure was similar to that observed in normal P12 tissue. Several in vitro treatments enhanced axon regeneration: removal of the entire midline region, inhibition of protein synthesis at the lesion site, and exposure to ABC chondroitinase. Furthermore, when the injured commissural axons were provided with a carpet of C6‐R cells (a radial glia‐like cell line), significantly more axons projected to the contralateral lobe of the IC. Taken together, these results suggest that the maturation of nonneuronal cells within the lesion site lead to failed axon regeneration in mature animals, and show that ameliorative strategies can be evaluated in vitro. J. Comp. Neurol. 470:80–92, 2004. © 2004 Wiley‐Liss, Inc.
Characterization of synaptogyrin 3 as a new synaptic vesicle protein
Authors: Belizaire Roger , Komanduri Cheryl , Wooten Kerry , Chen Ming , Thaller Christina , Janz Roger 
Published: January 2004

AbstractSynaptogyrins comprise a family of tyrosine‐phosphorylated proteins with two neuronal (synaptogyrins 1 and 3) and one ubiquitous (cellugyrin) isoform. Previous studies have indicated that synaptogyrins are involved in the regulation of neurotransmitter release. Synaptogyrin 1 is a synaptic vesicle protein; cellugyrin, by contrast, is absent from synaptic vesicles. In an effort to further characterize the synaptogyrin family, we studied the distribution of the synaptogyrin 3 protein in the nervous system. Subcellular fractionation and immunoprecipitation of synaptic vesicles from mouse brain showed that synaptogyrin 3 is associated with synaptic vesicles and that synaptogyrins 1 and 3 can reside on the same synaptic vesicle. Immunofluorescent staining of cultured hippocampal neurons confirmed the synaptic localization of synaptogyrin 3. Analysis of the relative distributions of synaptogyrins 1 and 3 in mouse brain revealed a more restricted expression pattern for synaptogyrin 3 compared to the ubiquitous distribution of synaptogyrin 1. Strong synaptogyrin 3 labeling was observed in the mossy fiber region of the hippocampus, substantia nigra pars reticulata, pallidum, and deep cerebellar nuclei. By comparison, the striatum and reticular and ventral posterolateral thalamic nuclei, which all showed synaptogyrin 1 labeling, contained significantly less synaptogyrin 3. Finally, we used in situ hybridization experiments to correlate synaptogyrin 3 mRNA in cell bodies with synaptogyrin 3 protein at synapses. Altogether, our data indicate that neuronal synaptogyrins are differentially expressed protein isoforms that may represent functionally distinct populations of synapses and/or synaptic vesicles. J. Comp. Neurol. 470:266–281, 2004. © 2004 Wiley‐Liss, Inc.
Re‐evaluation of the afferent connections of the pituitary in the weakly electric fish Apteronotus leptorhynchus: An in vitro tract‐tracing study
Authors: Corrêa Sônia A.L. 
Published: January 2004

AbstractThe pituitary plays a key role in the interaction between the brain and the endocrine system. We re‐examined the afferent connections of the pituitary in the weakly electric fish Apteronotus leptorhynchus using the in vitro application of dextran‐tetramethylrhodamine to the pituitary. The resultant retrograde labeling was analyzed. Application of the tracer to the rostral part, but not the caudal part, of the pituitary labels hypothalamic cells in the anterior division of the periventricular nucleus, the suprachiasmatic nucleus, and the nucleus tuberis lateralis pars anterior. Application of the tracer to either the rostral or caudal parts of the pituitary labels hypothalamic cells in the posterior division of the periventricular nucleus (RPPp), the nucleus hypothalamus caudalis (Hc), the nucleus hypothalamus anterioris, the ventral hypothalamic nucleus, and the central nucleus of the inferior lobe. Furthermore, cells in the rostral two‐thirds of the brainstem reticular formation (RF) project to the entire rostrocaudal extent of the pituitary. The largest projections to the pituitary are from Hc, PPp, and RF. Of the cells in Hc that project to the pituitary, almost all (96%) are small and the remainder are medium‐sized. Of the cells in PPp that project to the pituitary, about half are small or medium‐sized (44% and 56%, respectively). In Hc and PPp, about one‐third to one‐half of the cells that project to the pituitary are markedly elongated. The cells in RF that project to the pituitary are small (4%), medium‐sized (89%), or large (7%) and about four‐fifths of these cells are markedly elongated. With regard to the RF projections, the pituitary may receive copies of motor instructions and sensory information supplied by collaterals of the descending and ascending projection systems of RF cells. Thus, the ongoing motor activity of the animal and the ensuing sensory feedback from this activity could directly influence the pituitary. J. Comp. Neurol. 470:39–49, 2004. © 2004 Wiley‐Liss, Inc.
Dendritic morphology, local circuitry, and intrinsic electrophysiology of principal neurons in the entorhinal cortex of macaque monkeys
Authors: Buckmaster Paul S. , Alonso Angel , Canfield Don R. , Amaral David G. 
Published: January 2004

AbstractLittle is known about the neuroanatomical or electrophysiological properties of individual neurons in the primate entorhinal cortex. We have used intracellular recording and biocytin‐labeling techniques in the entorhinal slice preparation from macaque monkeys to investigate the morphology and intrinsic electrophysiology of principal neurons. These neurons have previously been studied most extensively in rats. In monkeys, layer II neurons are usually stellate cells, as in rats, but they occasionally have a pyramidal shape. They tend to discharge trains, not bursts, of action potentials, and some display subthreshold membrane potential oscillations. Layer III neurons are pyramidal, and they do not appear to display membrane potential oscillations. The distribution of dendrites and of axon collaterals suggests that neurons in layers II and III are interconnected by a network of associational fibers. Layer V and VI neurons are pyramidal and tend to discharge trains of action potentials. The distribution of dendrites and axon collaterals suggests that there is an associative network of principal neurons in layers V and VI, and they also project axon collaterals toward superficial layers. Importantly, entorhinal cortical neurons in monkeys appear to exhibit significant differences from those in rats. Morphologically, neurons in monkey entorhinal layers II and III have more primary dendrites, more dendritic branches, and greater total dendritic length than in rats. Electrophysiologically, layer II neurons in monkeys exhibit less sag, and subthreshold oscillations are less robust and slower. Some monkey layer III neurons discharge bursts of action potentials that are not found in rats. The interspecies differences revealed by this study may influence information processing and pathophysiological processes in the primate entorhinal cortex. J. Comp. Neurol. 470:317–329, 2004. © 2004 Wiley‐Liss, Inc.
Distinct muscle targets do not vary in the developmental regulation of brain‐derived neurotrophic factor
Authors: Vernon Elizabeth Marie , Oppenheim Ronald W. , Johnson James E. 
Published: January 2004

AbstractDeveloping neurons depend on many target‐derived signals. One of these signals is the neurotrophin brain‐derived neurotrophic factor (BDNF). Exogenous application of BDNF in vitro and in vivo rescues a population of lumbar motoneurons from programmed cell death. Given that BDNF does not rescue all motoneurons and that motoneurons differ in trophic factor receptor expression, subpopulations of motoneurons may have different sensitivities to the factor. These differences may be reflected in distinct target muscles specialized to produce different protein concentrations, or muscles may contain equal amounts of the factor and receptor expression determines motoneuron responsiveness. By using a sensitive electrochemiluminescent immunoassay (ECLIA), we measured normal developmental changes in BDNF protein concentration in anatomically and functionally distinct chick embryonic thigh muscles from E6 to E18. We found that there were no significant differences in BDNF protein concentration between muscles classified according to function (fast vs. slow) or anatomical position (flexor vs. extensor) and that the quantity of BDNF in the target did not appear to be activity dependent. These results suggest that, during development, the differences in the response of motoneurons to BDNF are not due to the anatomical or functional diversity of muscle targets. J. Comp. Neurol. 470:330–337, 2004. © 2004 Wiley‐Liss, Inc.