bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunohistochemical differentiation of electrophysiologically defined neuronal populations in the region of the rat hypothalamic paraventricular nucleus
Authors: Hoffman N. W. , Tasker J. G. , Dudek F. E. 
Published: January 2005

AbstractIntracellular recording and labeling were combined with neurophysin immunohistochemistry to study neurons in the paraventricular nucleus region of the rat hypothalamus. Neuronal membrane properties were examined in hypothalamic slices, and cells were labeled by injecting biocytin or Lucifer yellow. Slices were then embedded, sectioned, and immunohistochemically processed for neurophysin. Immunoreactivity patterns, and in some cases counterstaining, enabled determinations of the cytoarchitectonic positions of recorded cells to be made. Recorded cells were divided into three types according to their electrophysiological characteristics. The first type lacked low‐threshold Ca2+ spikes and displayed linear current‐voltage relations, a short time constant, and evidence for an A current. These were relatively large cells that were typically immunoreactive for neurophysin and were situated near other neurophysin‐positive neurons. The second type had relatively small low‐threshold potentials that did not generate bursts of Na+ spikes. These cells had heterogeneous current‐voltage relations and intermediate time constants. They did not label for neurophysin, and most were located in the parvicellular subregion of the paraventricular nucleus. The third type had large low‐threshold Ca2+ spikes that generated bursts of Na+ spikes, and these cells had nonlinear current‐voltage relations and long time constants. These neurons were dorsal or dorsolateral to the paraventricular nucleus and were not immunoreactive for neurophysin. These results indicate that paraventricular magnocellular neurons lack low‐threshold potentials, whereas paraventricular parvicellular neurons display low‐threshold potentials that generate one or two action potentials. Neurons that fire spike bursts from low‐threshold potentials are adjacent to the paraventricular nucleus, confirming earlier reports.
Nerve growth factor receptor immunoreactivity in the rat septohippocampal pathway: A Light and electron microscope investigation
Authors: Kawaja Michael D. , Gage Fred H. 
Published: January 2005

AbstractNerve growth factor receptor immunoreactivity in the septohippocampal pathway of adult Fischer 344 rats was assessed at the light and electron microscope level. The medial septum possesses immunoreactive somata, dendrites, axons, and terminals. Immunostained somata are either bipolar or multipolar in appearance. Dendritic processes of immunoreactive septal neurons are categorized into two groups: proximal dendrites with smooth plasma membranes and distal dendrites with numerous swellings. Immunoreactive axons within the septum are long and slender and do not possess varicosities. At the electron microscope level, immunoreactivity is confined predominantly to the plasma membrane of cell bodies and dendrites of septal neurons, as well as to the plasma membrane of axons and terminals. Both immunoreactive and nonimmunoreactive terminals that contain clear, spherical vesicles are observed contacting immunoreactive dendrites and somata. Although accumulations of vesicles are evident within these terminals at sites of contact, distinct synaptic specializations are difficult to distinguish due to the localization of reaction product on the apposing plasma membranes. Axons possessing immunoreactivity are also observed in the fimbria‐fornix pathway, a major source of afferent inputs to the hippocampus. Immunoreactive axons and terminals are topographically organized in the hippocampal dentate gyrus. The density of immunostained axons and terminals is highest immediately adjacent to the granular layer. In comparison, a moderate density of immunoreactive axons is found in the outer molecular layer and a weak density in the inner molecular, granular, and polymorphic layers. Immunoreactivity is found on the plasma membrane of small unmyelinated axons and terminals aggregated into clusters throughout the dentate gyrus. Definitive examples of axosomatic and axodendritic synapses possessing immunoreactivity presynaptically are not observed. Immunoreactive profiles within the medial septum and hippocampus also circumfuse a small number of intracerebral vessels. Ultrastructural examination reveals that immunoreactivity is present within a narrowed extension of the subarachnoid space and appears to be closely associated with the plasma membrane of leptomeningeal cell processes. The present study provides direct evidence for the cellular distribution of nerve growth factor receptor immunoreactivity in the medial septum and dentate gyrus in the adult rat and offers new insight into the ultrastructural localization of nerve growth factor receptor among septal cholinergic neurons and their efferent projections to the hippocampus.
Distribution of 3H‐GABA uptake sites in the nematode Ascaris
Authors: Guastella John , Stretton Antony O. W. 
Published: January 2005

AbstractThe distribution of uptake sites for the inhibitory neurotransmitter γ‐aminobutyric acid (GABA) in the nematode Ascaris suum was examined by autoradiography of 3H‐GABA uptake. Single neural processes in both the ventral and dorsal nerve cords were labeled with 3H‐GABA. Serial section analysis identified the cells of origin of these processes as the RMEV‐like and RMED‐like neurons. These cells belong to a set of four neurons in the nerve ring, all of which are labeled by 3H‐GABA. 3H‐GABA labeling of at least two other sets of cephalic neurons was seen. One of these pairs consists of medium‐sized lateral ganglia neurons, located at the level of the amphid commissure bundle. A second pair is located in the lateral ganglia at the level of the deirid commissure bundle. The position and size of these lateral ganglia cells suggest that they are the GABA‐immunoreactive lateral ganglia cells frequently seen in whole‐mount immunocytochemical preparations (Guastella et al., J Comp Neurol 307:584–597, 1991).Four neuronal cell bodies located in the retrovesicular ganglion were also labeled with 3H‐GABA. These cells, which are probably cholinergic excitatory motor neurons, do not contain detectable GABA‐like immunoreactivity. Heavy labeling of muscle cells was also observed. The ventral and dorsal nerve cord inhibitory motor neurons, which are known to contain GABA‐like immunoreactivity, were not labeled above background with 3H‐GABA.Together with the experiments reported previously (Guastella et al., J Comp Neurol 307:584–597, 1991), these results define three classes of GABA‐associated neurons in Ascaris: 1) neurons that contain endogenous GABA and possess a GABA uptake system; 2) neurons that contain endogenous GABA, but that either lack a GABA uptake system or possess a GABA uptake system of low activity; 3) neurons that possess a GABA uptake system, but that lack endogenous GABA.
Immunocytochemical localization of octopamine in the central nervous system of Limulus polyphemus: A light and electron microscopic study
Authors: Lee Helen M. , Wyse Gordon A. 
Published: January 2005

AbstractWe have determined the distribution and localization of the monoamine octopamrne in the prosomal central nervous system of the horseshoe crab, Limulus polyphemus, by light and electron microscopic immunocytochemistry. Sixteen discrete clustery of octopamine‐like immunoreactive neurons are situated bilaterally in the tritocerebrum and circumesophageal ring of fused thoracic ganglia. Two pairs of anterior clusters are located laterally in the cheliceral and first pedal ganglia; the remaining six pairs of clusters are located ventromedially in the second through fifth pedal ganglia, chilarial ganglia, and opercular ganglia. The immunoreactive somata range from about 40 to 100 μm in diameter and occur in clusters of 12–24 cells. There is extensive distribution of octopamine‐immunoreactive nerve fibers in Limulus; dense fiber tracts course anteroposteriorly through the central nervous system, and most neuropil regions are innervated by immunoreactive processes and terminals. This wide distribution of octopamine‐like immunoreactivity provides an anatomical basis for the several effects of octopamine in Limulus. We determined the subcellular localization of octopamine by postembedding immunoelectron microscopy. The immunogold‐labelled terminals are morphologically unique; they contain large, distinctively shaped dense‐core granules, typically cylindrical with a prominent indentation in one end. These large granules are 100–150 nm in diameter and range from 150–400 nm in length. The dense labelling of these unusual granules with immunogold particles indicates that octopamine is sequestered in or associated with the granules.
Arrestin mRNA expression, biosynthesis, and localization in degenerating photoreceptors of mutant rds mice retinas
Authors: Nir Izhak , Agarwal Neeraj 
Published: January 2005

AbstractThe retinal photoreceptors of the mutant rds mouse are unable to form normal outer segments. Eventually the abnormal cells die in the months following birth. The genetic defect in the rds mouse was recently localized to the peripherin gene that encodes a protein in the outer segment disc margin. Although this mutation may explain the morphogenetic defect, i.e., the failure to form outer segments, the reason for subsequent cell death is not clear. Previously, we demonstrated that the capability to synthesize opsin, an outer segment integral membrane protein, is not compromised by the morphogenetic defect although the opsin steady‐state content is considerably reduced, since it is not incorporated into an organized outer segment. We have now studied arrestin, a cytoplasmic protein that is part of the phototransduction cascade and appears to shuttle between the inner and outer segment during the light/dark cycle. Since rds mice lack outer segments, it was of interest to determine the effects of the photoreceptor abnormality on arrestin gene expression. Arrestin mRNA levels and protein synthetic rates were high in young rds retinas. When corrected for cell loss, the steady‐state arrestin content per cell in the rds retina was comparable to normal. However, in the absence of an outer segment, the total amount of arrestin is concentrated in the remaining inner segment. Consequently, a relatively high level of arrestin is present in the rds inner segment throughout the light/dark cycle. We suggest that the morphogenetic defect indirectly precipitates secondary effects such as the persistent presence of high levels of arrestin or other soluble proteins in the abnormal photoreceptor inner segment, nucleus, and synaptic terminal. This condition, if toxic to the cells, may compromise photoreceptor viability in the rds retina.
Dopaminergic innervation of substance P‐containing striatal neurons by fetal nigral grafts: An ultrastructural double‐labeling immunocytochemical study
Authors: Mendez I. , Elisevich K. , Flumerfelt B. 
Published: January 2005

AbstractEvidence for survival and growth of fetal substantia nigra grafts in host striatum and partial reversal of behavioural and biochemical deficits in the host animal is well documented. Afferent synaptic connections arising from the graft and contacting host structures have also been reported; however, the properties of the neurons receiving this input is less clear. The purpose of this study was to determine if substance P‐containing neostriatal neurons receive a dopaminergic input from nigral grafts. Fetal substantia nigra cell suspensions were stereotaxically implanted in the deafferented neostriatum of Wistar rats 2 weeks after a unilateral 6‐hydroxydopamine (6‐OHDA) lesion in the ipsilateral substantia nigra or medial forebrain bundle. The ultrastructural features of the graft‐host synaptic interactions were analysed by employing an electron microscope immunocytochemical double‐labeling technique. Tyrosine hydroxylase (TH) and substance P‐immunoreactive structures were simultaneously demonstrated by means of the peroxidase‐antiperoxidase method using two different chromogens with distinct reaction products easily differentiated at the light and electron microscope levels. TH‐immunoreactive sites were first demonstrated using 3,3′‐diaminobenzidine tetrahydrochloride (DAB); then substance P immunoreactivity was localized using benzidine dihydrochloride (BDHC). TH‐immunoreactive terminals of axons originating from the graft made synaptic contacts with substance P‐positive cell bodies and dendrites from the host. These results indicate that at least partial restoration of the normal nigrostriatal circuitry can be achieved following nigral grafts. The demonstration of specific synaptic input on host substance P neurons provides an anatomical basis for direct functional modulation of the deafferented host neostriatum by the nigral graft.
Prior optic nerve transection reduces capsaicin‐induced degeneration in rat subcortical visual structures
Authors: Ritter Sue , Dinh Thu T. 
Published: January 2005

AbstractCapsaicin is a neurotoxin capable of causing degeneration in specific sites throughout the neuraxis, including the suprachiasmatic nucleus (SCh), the ventrolateral geniculate nucleus (VLG), the intergeniculate leaflet (IGL), and the olivary and medial pretectal nuclei (OPT and MPT). In this experiment, we tested the hypothesis that capsaicin‐induced terminal degeneration in the SCh, VLG, IGL, OPT, and MPT results from destruction of retinal ganglion cells and their axonal projections to these sites. In the first experiment, silver stains were used to examine degeneration in the retina induced by systemic capsaicin treatment. Capsaicin caused degeneration of ganglion cells, bipolar cells, and nerve terminals in the retina, which could be observed between 2 and 24 hours after treatment. In the second experiment, 15‐day‐old rat pups were enucleated unilaterally. Five days or 2, 5, or 10 months later, they were injected systemically with capsaicin and killed 6 hours (pups) or 18 hours (adults) later for analysis with a cupric silver stain. In rats of all ages, prior monocular enucleation reduced or eliminated capsaicin‐induced degeneration in the contralateral SCh, VLG, IGL, OPT, and MPT. In the third experiment, rat pups were treated systemically with capsaicin or vehicle solution at 12 days of age and given unilateral intravitreal injections of cholera toxin conjugated to horseradish peroxidase (CT‐HRP) 3 days prior to sacrifice at 20 days of age. Transport of CT‐HRP to the SCh, VLG, IGL, MPT, and OPT was attenuated but not abolished by capsaicin pretreatment. Results suggest that capsaicin causes degeneration in the SCh, VLG, IGL, MPT, and OPT by selective destruction of a subpopulation of retinal ganglion cells with axonal projections to these sites.
GABA and enkephalin in the lateral septum of the guinea pig: Light and electron microscopic evidence for interrelations
Authors: Beauvillain J. C. , Mitchell V. , Tramu G. , Mazzuca M. 
Published: January 2005

AbstractTract tracing techniques combined with immunohistochemistry in rats and guinea pigs have demonstrated the existence of a hypothalamo‐lateral septum enkephalinergic pathway. Numerous enkephalinergic nerve endings encompass cell bodies located in the lateral septum. The present immunocytochemical study, at light and electron microscopic levels, was undertaken in the guinea pig brain to determine whether the contacted perikarya contain γ‐aminobutyric acid (GABA).The antisera against GABA revealed the presence of immunoreactive cell bodies throughout the lateral septum. At the light microscopic level, most GABA neurons appeared round while others were oval with one or two emerging dendrites. Ultrastructurally, cell bodies displayed a moderate number of organelles and a pale nucleus with frequent indentations of the nuclear envelope.The precise relationship between GABA neurons and enkephalinergic terminals was examined by means of a double‐immunostaining method showing that 60% of cell bodies receiving synaptic inputs from enkephalinergic afferents contained GABA.These results show that the hypothalamo‐septal enkephalinergic pathway prominently innervates GABA‐containing neurons and also provide anatomical basis suggesting a disinhibitory role for this enkephalinergic tract.
Patterns of sensory intermodality relationships in the cerebral cortex of the rat
Authors: Paperna Tamar , Malach Rafael 
Published: January 2005

AbstractPatterns of connections underlying cross‐modality integration were studied by injecting distinguishable, retrograde tracers (Fluoro‐Gold and diamidino yellow) in pairwise manner into different sensory representations (visual, somatosensory, and auditory) in the cerebral cortex of the rat.In agreement with previous single tracer studies, our results indicate that the central core of sensory areas receives projections mainly from a set of association areas located in a ringlike fashion along the margin of the cortical mantle. The visual cortex received projections from areas 48/49, area 29d, posterior agranular medial cortex (AGm), area 11, area 13, and area 35. All these areas were also connected to the auditory cortex with the exception of areas 29d and AGm. However, lateral to area 29d and posterior AGm, a band of neurons projecting to the auditory cortex was present. Somatosensory cortex was connected mainly with the more anterior aspect of the hemisphere, which included primary motor area, area 11, and area 13.The patterns of intermodality relationships revealed in the present study were of two main categories. In the anterior, and lateral areas, an intermingling of cells projecting to different sensory modalities was observed. In contrast, in areas located along the medial aspect of the hemisphere, cells connected to different sensory modality representations tended to be segregated from each other. Postsubicular cortex (areas 48/49) contained both intermingled and segregated groups of cells. The incidence of clearly identified double‐labeled cells concurrently projecting to two different sensory representations was extremely rare. These patterns may form a substrate for different levels of cross‐modal sensory integration in the rat cortex.
Cortical areas in the medial frontal lobe of the cat delineated by quantitative analysis of thalamic afferents
Authors: Musil S. Y. , Olson C. R. 
Published: January 2005

AbstractThe aim of these experiments was to establish the number and location of connectionally distinct areas in the medial frontal lobe of the cat. Thirty deposits of distinguishable retrograde tracers were placed at restricted sites spanning the medial frontal lobe in 16 cats. Following each deposit, the number of retrogradely labeled neurons in each of 17 thalamic nuclei was determined. Variations of the thalamic labeling pattern dependent on the location of the cortical tracer deposit were then analyzed by a quantitative procedure.The results indicate that the medial frontal lobe contains three fundamental divisions: the anterior cingulate area, medial area 6, and the medial prefrontal district. The anterior cingulate area derives its strongest thalamic input from the anteromedial nucleus. Medial area 6 is the target of afferents originating in a dorsolateral sector of the mediodorsal nucleus and in the ventroanterior nucleus. Medial prefrontal cortex is heavily innervated by pathways originating in the core of the mediodorsal nucleus and in the principal ventromedial nucleus. Within each major district, thalamic connectional patterns exhibit graded regional variation, with the result that, whereas the connections of the district are not uniform, it is difficult to define further discrete subdivisions.We discuss these results in relation to previously proposed schemes for parcellation of the cat's medial frontal lobe and conclude that the infralimbic and prelimbic areas (areas 25 and 32) of previous systems are best understood not as discrete areas but as ventral and intermediate sectors of a continuous medial prefrontal domain.
Nerve growth factor receptor immunoreactivity in the new world monkey (Cebus apella) and human cerebellum
Authors: Mufson Elliott J. , Higgins Gerald A. , Kordower Jeffrey H. 
Published: January 2005

AbstractThe present study used the NGFR‐5 monoclonal antibody raised against human nerve growth factor receptor (NGFR) to determine the extent of NGFR immunoreactivity within the embryonic and young adult Cebus apella cerebellum as well as the human cerebellum. Immunohistochemically processed tissue revealed NGFR expressing Purkinje cell somata, axons, and dendrites, the latter being observed within the molecular layer of both adult species. Within all regions of the cerebellum we observed both darkly and lightly immunostained Purkinje cells. The proximal axons of these cells, which were visualized for short distances within the granular cell layer, appeared to contain bulbous aggregates of reaction product. In sagittal sections, the full extent of the Purkinje cell dendritic tree was observed in the more lightly stained portions of the cerebellum. In situ hybridization experiments revealed NGFR mRNA within Purkinje cells in a pattern similar to that seen with immunohistochemistry. The distribution of NGFR immunoreactivity within the cerebellum exhibits a general topographic organization with the heaviest and most consistent staining occurring within the archi‐ and neocerebellum and weaker staining within the paleocerebellum. In fetal Cebus monkey cerebellum obtained at gestational day 50 and 70, NGFR immunoreactivity was observed as a band composed of developing Purkinje cell neurites. These profiles were seen in the paleo‐ and neocerebellum, but not the archicerebellum. The present investigation is the first demonstration of NGFR immunoreactive profiles in the adult monkey and human cerebellum. These findings suggest that nerve growth factor may influence locomotor and vestibular behaviors that are mediated by cerebellar circuitry. The precise mode of action for the NGF/NGFR system within the cerebellum remains to be determined.
Comparative aspects of the basal ganglia‐tectal pathways in reptiles
Authors: Medina Loreta , Smeets Wilhelmus J. A. J. 
Published: January 2005

AbstractTo determine how the basal ganglia in reptiles may influence visuomotor behavior, the connections from the basal ganglia to the tectum of the midbrain were studied in several species of reptiles. Immunohistochemical studies by means of antibodies against Leu‐enkephalin (LENK) as well as experimental hodological studies with anterograde (PHA‐L) and retrograde (HRP, Fluorogold, Cholera toxin) tracers were carried out. The results indicate that within the class of Reptilia, two different patterns occur: one in which information from the basal ganglia is relayed to the tectum via the substantia nigra as well as via a pretectal, enkephalinergic cell group, and another one in which only the ventral route, via the substantia nigra, is present. The former pattern is found in turtles, crocodiles, and the lacertid lizards Podarcis and Gallotia, and the latter pattern in the gekkonid lizards Gekko and Eublepharis, in Varanus, and in the snakes Python and Thamnophis. The presence or absence of the pretectal relay center is reflected in the laminar distribution of LENK immunoreactivity in the tectum.The apparent lack of a pretectal relay in nocturnal gekkonids and in snakes underlines the hypothesis (Reiner et al., '84: T.I.N.S. 7:320–325) that a de‐emphasis of visual‐basal ganglia mechanisms has occurred during the evolution of ancestral reptiles to modern mammals.