bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunocytochemical localization of GABAA receptors in goldfish and chicken retinas
Authors: Yazulla Stephen , Studholme Keith M. , Vitorica Javier , De Blas Angel L. 
Published: January 2005

AbstractA monoclonal antibody (mAb 62–3G1) to the GABAA receptor/benzodiazepine receptor/Cl− channel complex from bovine brain was used with light and electron microscopy in goldfish retina and light microscopy in chicken retina to localize GABAA receptor immunoreactivity (GABAr‐IR). GABAr‐IR was found in the outer plexiform layer (OPL) in both species, in three broad bands in the inner plexiform layer (IPL) of goldfish, and in seven major bands of the chicken IPL. A small percentage of amacrine cell bodies (composing at least three types) were stained in chicken. In goldfish OPL, GABAr‐IR was localized intracellularly and along the plasma membrane of cone pedicles, whereas rod spherules were lightly stained, but always only intracellularly. In chicken, all three sublayers of the OPL were GABAr‐IR. The presence of GABAr‐IR on photoreceptor terminals is consistent with data indicating feedback from GABAergic horizontal cells to cones. In the goldfish IPL, GABAr‐IR was localized to postsynaptic sites of amacrine cell synapses; intracellular staining of processes in the IPL also was observed in presumed “GABAergic” targets. A comparison of GABAr‐IR with the distributions of 3H‐muscimol uptake/binding, glutamate decarboxylase‐IR, GABA‐IR, and 3H‐GABA uptake in the IPL showed either a reasonable correspondence or mismatch, depending on the marker, species, and lamina within the IPL. The distribution of GABAr‐IR in the retina corresponded better with the 3H‐muscimol than with 3H‐benzodiazepine binding patterns yet overall was in excellent agreement with many other physiological and anatomical indicators of GABAergic function. We suggest that intracellular GABAr‐IR represents the biosynthetic and/or degradative pathway of the receptor and we conclude that mAb 62–3G1 is a valid marker of GABAA receptors in these retinas and will serve as a useful probe with which to address the issue of mismatches between the localization of GABAA receptors and indicators of presynaptic GABAergic terminals.
Descending projections from auditory brainstem nuclei to the cochlea and cochlear nucleus of the guinea pig
Authors: Winter Ian M. , Robertson Donald , Cole K. Stewart 
Published: January 2005

AbstractProjections from auditory brainstem nuclei to the cochlear nuclei in the guinea pig were studied by injection of two retrograde fluorescent neuronal tracers. For seven experiments fast blue was injected into the scala tympani of one cochlea and diamidino yellow was injected into dorsal or anteroventral cochlear nucleus of the same side. The results show that the efferent projections to the cochlea and cochlear nucleus generally form two separate neuronal systems even though they share many common nuclei of origin. The largest projections to the cochlear nucleus come bilaterally from the lateral and ventral nuclei of the trapezoid body. Other nuclei, the lateral superior olive, the ventral nucleus of the lateral lemniscus, the dorsomedial periolivary nuclei, and the medial nucleus of the trapezoid body showed an ipsilateral bias in their projections to the cochlear nucleus.An upper limit of 3.5% of the medial system olivocochlear efferent neurones projecting to the cochlea were labelled with both diamidino yellow and fast blue, suggesting that few efferent neurones projecting to the cochlea send collaterals to the cochlear nucleus in this species. However, the site of medial system olivocochlear efferent collateral terminations is the granule cell area for the cat, mouse, and gerbil. When diamidino yellow was injected in the superficial layers of the cochlear nucleus, including the superficial granule cell layer of the ventral cochlear nucleus, approximately 3.6% of medial system olivocochlear efferents projecting to the cochlea sent collaterals to the cochlear nucleus.In three animals fast blue was injected into the cochlear nucleus and diamidino yellow into the cochlea. These experiments revealed a greater proportion of the medial system olivocochlear efferents projecting to the cochlea sending collaterals to the cochlear nucleus, but this proportion was still less than 10%. These results were confirmed by the extracellular injection of horseradish peroxidase into the intraganglionic spiral bundle. Only three medial system olivocochlear efferents were observed to send collaterals to the cochlear nucleus. This number was less than 10% of all labelled medial system fibres.Although these experiments suggest that in the guinea pig the number of olivocochlear efferents sending collaterals to the cochlear nucleus is considerably smaller than is found for the cat, mouse, and gerbil, it is not possible with the current experimental procedures to conclude whether the results are due to species or methodological differences.
Multiple types of neuropeptide Y‐containing neurons in primate neocortex
Authors: Kuljis Rodrigo O. , Rakic Pasko 
Published: January 2005

AbstractThe avidin‐biotin‐peroxidase method was used at the light and electron microscopic levels to analyze neuropeptide Y (NPY)‐containing neurons in the neocortex of six adult macaque monkeys. Regions studied included various sensory, motor, limbic, and association areas, designated as 17, 18, 7, 22, 3, 4, 6, 24, and 9 by Brodmann (Beiträge zur Histologischen Lokalisation der Grosshirnrinde. Leipzig: Barth, '06). Several types of NPY‐containing neurons can be distinguished by their laminar location, by the size of their perikarya, and by the size, shape, and pattern of ramification of their processes: (1) layer I small local circuit neurons; (2) layer II granule cells; (3) aspiny stellate cells located in layers II–III and V–VI, with long, slender dendrites; (4) sparsely spiny stellate cells; (5) aspiny stellate cells with long, horizontally oriented dendrites, whose cell body is situated in layer VI; (6) Martinotti cells in areas 9, 7, and 24; and (7) multipolar neurons situated in the white matter subjacent to the cortical gray. The possibility of additional neuronal types containing NPY is suggested by labeled densely spinous dendrites in area 6 and recurving axons and axonal loops in the supragranular layers in areas 7 and 9. No NPY‐containing neurons were found in layer IV of any area, except layers IVA and B of the visual cortex. Likewise, nonneuronal elements were not labeled. The regional differences in the distribution of some NPY‐containing neuron types may reflect adaptations of local neuronal circuits for specialized functions.
Fluorescent histochemical localization of neutral endopeptidase‐24.11 (enkephalinase) in the rat spinal cord
Authors: Back Stephen A. , Gorenstein Charles 
Published: January 2005

AbstractThe localization of neutral endopeptidase‐24.11 (E.C. 3.4.24.11; enkephalinase) in rat spinal cord was investigated by a novel fluorescent histochemical method. Enkephalinase was localized by using a coupled enzyme assay based upon the sequential cleavage of the synthetic peptide substrate glutaryl‐ala‐ala‐phe‐4‐methoxy‐2‐naphthylamide by enkephalinase and exogenous aminopeptidase M. Enzyme distribution was examined in segments from cervical, thoracic, lumbar, and sacral cord.At all spinal cord levels, enkephalinase was localized to discrete regions of the gray matter. The substantia gelatinosa displayed rich enkephalinase staining which overlapped the inner and outer zones of lamina II. A staining pattern similar to that observed in lamina II was observed in the spinal trigeminal nucleus in the medulla. In lamina III the enzyme was associated with small and medium‐sized cells. Lamina IV showed staining associated with medium‐sized and large cell bodies. The medial boundary of the dorsal gray of laminae IV and V had medium‐sized fusiform cells which stained for enkephalinase. In the lateral reticulated areas of lamina V, enkephalinase reaction product was localized to scattered medium‐sized and large cells compressed against the white matter of axon bundles. Staining in lamina VI was similar in appearance to lamina V. Enkephalinase reaction product was widely distributed in the ventral horn. Numerous ventral horn motor neurons of varied size and morphology in laminae VIII and XI stained richly for the enzyme. The enzyme was also localized to medium‐sized and large cells in lamina X and to cells of the central cervical nucleus.The size and morphology of the cell types associated with the enzyme supported a neuronal association for enkephalinase. The regional distribution of the enzyme overlapped that of enkephalin‐ and substance‐P rich regions of the spinal cord. These findings support a role for enkephalinase in the metabolic regulation of centrally acting neuropeptides.
Neural organization of the masseter muscle in the pig
Authors: Herring Susan W. , Anapol Fred C. , Wineski Lawrence E. 
Published: January 2005

AbstractThe neural organization of the pig masseter, an architecturally and functionally compartmentalized muscle, was investigated by using dissection, glycogen depletion, evoked electromyography, and counts of axon numbers at various levels along the masseteric nerve. The masseteric nerve enters the muscle as two rostral branches, which also supply the zygomatico‐mandibularis, and a more caudal main branch, which soon divides into four terminal nerves with variable distributions. Stimulation of filaments containing roughly 50 extrafusal motor axons resulted in glycogen depletion of 5–20% of the muscle fibers in very small subvolumes of the masseter; the affected subvolumes were delimited by perimysium. Electromyography after stimulation of various branches of the nerve confirmed the distributions deduced from anatomy and further indicated that axons do not branch between the rostral and main nerve branches but may occasionally do so among the more distal terminal branches of the main branch. The proximal trunk of the masseteric nerve contains about 3,500 myelinated fibers with a bimodal size distribution. Approximately 1,000 of the larger fibers were estimated to be extrafusal motor axons. Along the proximal trunk of the nerve, fibers were constantly rearranged; coupled with the observation that the locations of motor unit territories were usually not related to the position of the stimulated axons within the nerve, this suggests that the nerve trunk is not strictly ordered somatotopically.
Hormonal control of neuron number in sexually dimorphic spinal nuclei of the rat: III. Differential effects of the androgen dihydrotestosterone
Authors: Sengelaub D. R. , Nordeen E. J. , Nordeen K. W. , Arnold A. P. 
Published: January 2005

AbstractThe spinal cord of the rat contains two sexually dimorphic nuclei: the spinal nucleus of the bulbocavernosus (SNB) and the dorsolateral nucleus (DLN). These nuclei and the perineal muscles they innervate are present in males but reduced or absent in females. The sex difference in motoneuron number in these nuclei is due to an androgen‐regulated motoneuron death. Developing females treated with the androgen testosterone propionate (TP) have a fully masculine number of SNB and DLN motoneurons and retain the perineal muscles they would normally have lost. Paradoxically, females treated prenatally with the androgen dihydrotestosterone propionate (DHTP) also retain the perineal musculature but as adults lack the SNB motoneurons which would normally innervate them. The SNB target muscles retained by DHTP females are anomalously innervated by motoneurons in the DLN.Counts of motoneurons and degenerating cells in the developing SNB of DHTP‐treated females showed that their feminine number is the result of a failure of DHTP to prevent the death of SNB motoneurons. Furthermore, the peak number of SNB motoneurons was below that of normal females, suggesting that DHTP treatment may also have inhibited motoneuronal migration. However, DHTP treatment fully masculinized both motoneuron number and degenerating cell counts in the DLN of these females, and it is this masculinized DLN that gives rise to the anomalous projection. Taken together, these results suggest that the effects of different androgens during development are specific and complex, involving the regulation of motoneuron death, migration, and specification of peripheral projections.
Origins of the descending spinal projections in petromyzontid and myxinoid agnathans
Authors: Ronan Mark 
Published: January 2005

AbstractThe origins of the descending spinal pathways in sea lampreys (Petromyzon marinus), silver lampreys (Ichthyomyzon unicuspis), and Pacific hagfish (Eptatretus stouti) were identified by the retrograde transport of horseradish peroxidase (HRP) placed in the rostral spinal cord. In lampreys, the majority of HRP‐labeled cells were located along the length of the brainstem reticular formation in the inferior, middle, and superior reticular nuclei of the medulla, mesencephalic tegmentum, and nucleus of the medial longitudinal fasciculus. Labeled reticular cells included the Mauthner and Müller cells. Horseradishperoxidase‐filled cells were also present in the descending trigeminal tract, intermediate and posterior octavomotor nuclei, and a diencephalic cell group, the nucleus of the posterior tubercle. As in lampreys, the reticular formation of the Pacific hagfish was the largest source of descending afferents to the spinal cord. Labeled cells were found in the dorsolateral and ventromedial reticular nuclei, the dorsal tegmentum at the juncture of the medulla and midbrain, and the nucleus of the medial longitudinal fasciculus. Additional medullary cells projecting to the cord were located in the perivagal nucleus, the central gray, and the anterior and posterior magnocellular octavolateralis nuclei. The existence of reticulospinal and possible vestibulo‐, trigemino‐, and solitary spinal projections in lampreys and hagfishes and the wide distribution of these pathways in jawed vertebrates suggest that they evolved in the common ancestor of gnathostomes and both groups of jawless fishes. However, descending spinal pathways from the cerebellum, red nucleus, and telencephalon appear to be gnathostome characters.
Morphology of peptide‐immunoreactive neurons in the rat central nucleus of the amygdala
Authors: Cassell M. D. , Gray T. S. 
Published: January 2005

AbstractThe morphological characteristics of peptide‐immunoreactive neurons in the rat central nucleus of the amygdala were examined. Observations were compared with details of neuron morphology available from Golgi‐stained tissue to determine whether peptide immunoreactivity was associated with specific cell types in the central nucleus. The lateral subdivision (CL) of the central nucleus contained mainly medium‐sized, densely spiny neurons. Larger, pyramiform spiny neurons; medium‐sized, sparsely spinous neurons; and small, aspinous cells were also present in CL. Somatostatin−, neurotensin−, corticotropin‐releasing factor (CRF)‐, and enkephalin‐immunoreactive neurons in CL were characterized as the medium spiny and larger, pyramiform types. No obvious morphological differences were evident among medium spiny neurons containing different peptides. In the medial subdivision, substance P, neurotensin, somatostatin, and CRF were present within pyramiform, sparsely spinous neurons with long dendrites. Galanin immunoreactivity in the medial subdivision was associated with moderately spiny, pyramiform neurons and a larger, aspinous, polygonal neuron. The ventral subdivision of the central nucleus contained neurons similar to those found in the adjacent medial and lateral subdivisions. In addition, this subdivision contained a characteristic ovoid neuron with long, sparsely spinous dendrites. Vasoactive intestinal polypeptide (VIP) and neurotensin appeared to be present within this cell type. In the lateral capsular subdivision, neurotensin and enkephalin were present in cells resembling the medium spiny neurons characteristic of this part of the central nucleus. Numbers of spindle‐shaped, bipolar somatostatin, and VIP neurons were identified in the medial, lateral, and ventral subdivisions.The present results provide evidence for a heterogeneous morphology of peptide‐immunoreactive neurons in the rat central nucleus that are distributed across cytoarchitectonic boundaries. Except for substance P, neuropeptides in the central nucleus appear to be expressed by a variety of neurons rather than morphologically characteristic types of cell.
Nigrotectal projection to the inferior colliculus: Horseradish peroxidase transport and tyrosine hydroxylase immunohistochemical studies in rats, cats, and bats
Authors: Olaźbal U. E. , Moore J. K. 
Published: January 2005

AbstractThe present study investigated descending projections from the substantia nigra to the auditory tectum. Small (0.02–0.05 μl) injections of a 30–60% aqueous solution of horseradish peroxidase (HRP) were made unilaterally into the inferior colliculus in rats, cats, and bats (Eptesicus fuscus). Tissue blocks including the substantia nigra, superior colliculus, and inferior colliculus were removed, sectioned, and processed for visualization of HRP. Results show that the substantia nigra, pars lateralis, projects to the inferior colliculus ipsilaterally. In addition, retrogradely labeled cells are found dorsal to the pars lateralis, in a column within the lateral tegmental area of the midbrain. Analysis of injection sites suggests that the principal target of this nigral projection is the dorsal and rostral pericentral region of the inferior colliculus. Immunohistochemical studies with an antibody to tyrosine hydroxylase demonstrate catecholaminergic neurons within the pars lateralis and lateral tegmentum that are similar in location and morphology to one class of HRP retrogradely labeled cells within these structures. These immunohistochemical studies also demonstrate a plexus of fine, varicose tyrosine hydroxylase‐positive axons in the rostral pericentral region of the colliculus. The presence of this nigrotectal projection to the inferior colliculus is discussed in relation to its possible role in the control of acousticomotor behavior.
Tyrosine phosphorylation in the postnatal rat brain: A developmental, immunohistochemical study
Authors: Tillotson Meryl Lee , Wood John G. 
Published: January 2005

AbstractWe have used antibodies against phosphotyrosine to probe 50‐μm cerebellar sections from rats of various ages as well as sections of adult brainstem, cerebrum, and olfactory bulb to investigate the developmental appearance of this phosphorylation system as revealed by light microscopy. While the overall intensity of staining in the cerebellum was highest at 7 days, the pattern of staining in the adult is quite disparate from that seen in younger animals. From 10 to 21 days postnatal, staining is associated primarily with the white matter and/or the lower premigratory zone of the external granular layer and adjacent formative molecular layer. While the temporal and spatial appearance of phosphotyrosine immunoreactivity corresponds well to the established patterns of axonal growth in these areas, we cannot at the light level ascertain whether the immunoreactivity is intrinsic or extrinsic to the growing fibers. In animals 28 days and older, however, staining is restricted to a subpopulation of multipolar cells distributed throughout the cerebellum, as well as the olfactory bulb, cerebrum, and brainstem. The phosphotyrosine‐positive cells in the adult cerebellum are not comparable to glial‐fibrillary‐acidic‐protein‐immunoreactive elements with regard to morphology or distribution, and they fail to colocalize with neuronal somata stained with anti‐microtubule‐protein‐2 antibodies. While it appears that the radial fibers of the Bergmann glia in the external granular layer stain at 7 days, there is no staining detected in the mitotically active neuroblasts of this layer at any age. We conclude that in the immature cerebellum, the majority of tyrosine phosphorylation detectable by this method may be involved in the formation and growth of axonal processes. In the adult rat cerebellum, however, it is most likely that detectable tyrosine phosphorylation occurs in the somata and processes of a neuroglial subpopulation.
Morphology of jaw‐muscle spindle afferents in the rat
Authors: Dessem Dean , Taylor Anthony 
Published: January 2005

AbstractThe morphology of jaw‐muscle spindle afferents in the rat has been studied by intra‐axonal injection of horseradish peroxidase. All stained axons were located in the motor root of the trigeminal nerve and could be traced dorsomedially to the vicinity of the trigeminal motor nucleus, where they divided into an ascending branch in the tract of the mesencephalic nucleus and a descending branch in the tract of Probst. Axon collaterals and swellings on fine collateral branches presumed to be synaptic boutons were located in the following regions: the trigeminal motor nucleus, the region dorsal to the trigeminal motor nucleus including the supratrigeminal nucleus, the parvicellular reticular formation immediately caudal to the trigeminal motor nucleus, the reticular formation at the level of the facial nucleus, and the caudal portion of the mesencephalic nucleus. No evidence of a projection to the cerebellum was observed. Boutons were most numerous in the region surrounding the trigeminal motor nucleus, especially dorsally. Here they were not demonstrated in close proximity to counterstained cells, and therefore it was not possible to determine how many of these contacts are located on cells in this region and how many are on the distal dendrites of trigeminal motorneurons. Boutons located within the trigeminal motor nucleus were always confined to a small portion of the nucleus and were significantly larger than those located dorsally. Some boutons were found in close apposition to trigeminal motor‐neurons and presumably make somatic contacts. These results suggest that jaw‐muscle spindle afferents make somatic and proximal dendritic contacts with only a limited number of trigeminal motorneurons and also project to masticatory interneuronal regions dorsal and caudal to the motor nucleus.