摘要:

AbstractSubstance P (SP) is a neuropeptide that acts as a neurotransmitter or a neuromodulator in the retina. The aim of this study was to identify the type(s) and the distribution of the SP‐immunoreactive (SP‐IR) cells in the human retina. We have used an antiserum to SP to immunostain neurons in postmortem human retinae. Immunostained retinae were processedwith the avidin‐biotin complex (ABC) to visualize the cells either whole mounted in glycerol or embedded in plastic. Some retinae were also sectioned at 20 μm in order to obtain radial views of stained cells. SP‐IR amacrine cells stain intensely and appear to be of a single type in the human retina. They are large‐field cells with large cell bodies (16 μm diameter) lying in normal or displaced positions on either side of the inner plexiform layer (IPL). Their sturdy, spiny, and appendage‐bearing dendrites stratify in stratum 3 (S3) of the IPL, where many overlapping, fine dendrites intermingle to form a plexus of stained processes. Either cell bodies or primary dendrites emit an “axon‐like” process that, typically, divides into two long, fine processes, which run in opposite directions for hundreds of micrometers in S5 and S3 before disappearing as distinct entities in the stained plexus in S3. Long, fine dendrites also pass from the dendritic plexus to run in S5 and down to the nerve fiber layer to end as large varicosities at blood vessel walls. In addition, fine processes are emitted from the dendritic plexus that runs in S1, and some pass up to the outer plexiform layer (OPL) to run therein for short distances. The SP‐IR amacrine cell has many similaritiesto the thorny, type 2 amacrine cells described from Golgi studies.In addition to the SP‐IR amacrine cells, a presumed ganglion cell type is faintly immunoreactive. Its 20–22 μpm cell body gives rise to a radiate, sparsely branched, widespreading dendritic tree running in S3. Its dendrites and cell body become enveloped by the more intensely SP‐IR processes and boutons from the SP‐IR amacrine cell type. The SP‐IR ganglion cell type most resembles G21 from a Gol

ISSN:0092-7317    

DOI:10.1002/cne.903560402

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA neutral and basic amino acid transporter (NBAT) cloned from rat kidney was recently localized to enteroendocrine cells and enteric neurons. We used an antibody directed against a synthetic peptide representing a putative extracellular domain of NBAT to determine whether this transporter was also present in other endocrine and neural tissues, including rat adrenal gland, brainstem, and spinal cord. Abundant, highly granular labeling for NBAT was observed in the cytoplasm of chromaffin and ganglion cells in the adrenal medulla. A small population of intensely labeled varicose processes was also seen in both the cortex and the medulla of the adrenal gland. More numerous, intensely labeled varicose processes were detected in brainstem and spinal cord nuclei, including the locus coeruleus, rostral ventrolateral medulla, nuclei of the solitary tract, dorsal motor nucleus of the vagus, and intermediolateral cell column of the thoracic spinal cord. Significant perikaryal labeling for NBAT was only detected in brainstem and spinal cord following intraventricular colchicine treatment, which increased the number, distribution, and intensity of NBAT‐immunolabeled cells. These NBAT‐immunoreactive perikarya were most numerous in the locus coeruleus, rostral ventrolateral medulla, nuclei of the solitary tract, and raphe nuclei. Ultrastructural examination of the nuclei of the solitary tract of normal rats showed that NBAT was localized predominantly to axon terminals. Within these labeled terminals, NBAT was associated with large dense core vesicles and discrete segments of plasma membrane. The observed localization of NBAT suggests that this renal specific amino acid transporter subserves a role as a vesicular or plasmalemmal transporter in monoamine‐containing cells, including chromaffin cells and autonomic neurons. © 1995 Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903560403

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractDuring development, interaction with target cells plays a critical role in the regulation of survival of afferent neurons. In an attempt to define the role of target cells in the adult central nervous system, the somatodendritic morphology and survival of adult cuneate neurons deprived of their targets by in situ injection of kainic acid in the rat thalamus were studied.In neuron‐specific, enolase‐immunostained sections, a 20% decrease in the mean longest diameter of the labeled cells was detected at 4 months postlesion. This somatic atrophy was accompanied by a loss of distal dendritic arborizations as observed after labeling by intracellular diffusion of horseradish peroxidase. Cytochrome oxidase staining did not reveal detectable alterations of the metabolic activity of these neurons, and an ultrastructural study also failed to demonstrate major changes in the neuronal somata. Cell counts indicated a much delayed death of 25% of the neurons at 10 months postlesion, whereas no neuronal death was detected at 7 months. The glial cells appeared unaltered both in number and in immunolabeling when using OX‐42 antibodies or antiglial fibrillary acidic protein (anti‐GFAP) antibodies.Results obtained in this time‐course study indicate that neuronal death and alteration of the somatodendritic morphology are much delayed events after excitotoxic loss of targets. Somatodendritic atrophy occurs several months postlesion, and neuronal death occurs close to 1 year after lesion. These results suggest that the hypothesis of a necessary continuous trophic support by target cells does not hold as firmly for the adult central nervous system as during development. © 1995 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903560404

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractLungfishes, which share similarities with both fishes and amphibians, represent an interesting group in which to investigate the evolutionary transition from fishes to tetrapods. In the present study, we have investigated the localization and biochemical characteristics of neuropeptide Y (NPY)‐immunoreactive material in the central nervous system of the African lungfish,Protopterus annectens. NPY‐immunoreactive cell bodies were found in various regions of the brain, most notably in the telencephalon (septal area, ventral striatum, and nucleus accumbens), in the diencephalon (preoptic nucleus, periventricular region of the hypothalamus, and ventral thalamus), and in the tegmentum of the mesencephalon. A strong immunoreaction was also detected in cell bodies of the nervus terminalis. Immunoreactive nerve fibers were particularly abundant in the ventral striatum, the nucleus accumbens, the diagonal band of Broca, the hypothalamus, and the mesencephalic tegmentum. Positive fibers were also seen in the median eminence and in the neural lobe of the pituitary. The NPY‐immunoreactive material localized in the brain and pituitary was characterized by combining high‐performance liquid chromatography (HPLC) analysis and radioimmunological quantitation. The displacement curves obtained with synthetic porcine and frog NPY and serial dilutions of brain and pituitary extracts were parallel. Reversed‐phase HPLC analysis of telencephalon, diencephalon, and pituitary extracts resolved a major NPY‐immunoreactive peak that coeluted with frog NPY. The similarity between the distribution of NPY‐containing neurons and the biochemical characteristics of the immunoreactive peptide in the brain of lungfish and frog strongly favors a close phylogenetic relationship between dipnoans and amphibians. © 1995 W

ISSN:0092-7317    

DOI:10.1002/cne.903560405

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractNeonatal mouse cerebellar cultures exposed to cytosine arabinoside for the first 5 days in vitro to destroy granule cells and compromise glia undergo a circuit reorganization featured by profuse sprouting of Purkinje cell recurrent axon collaterals, which hyperinnervate the somata of other Purkinje cells and project to Purkir&cell dendritic spines. Such granuloprival cultures were exposed continuously from explanation to tetrodotoxin and elevated levels of magnesium to block neuronal activity. A similar circuit reorganization occurred, except that there was a reduction in the number of axospinous synapses and Purkinje cell axosomatic synapses, which in this case were all inhibitory. Functionally, after recovery from the blockade, granuloprival cultures developed sustained cortical hyperactivity, which was consistent with the reduction of inhibitory synapses. While the absence of neuronal activity did not prevent reorganizational changes following granule cell loss, the full development of the inhibitory circuitry was not attained. These results further support the concept that spontaneous neuronal activity is necessary for the complete development of inhibitory synapses. © 1995 Wiley‐Liss, I

ISSN:0092-7317    

DOI:10.1002/cne.903560406

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe distribution of premotor neurons for trigeminal motor nucleus neurons innervating the jaw‐closing and jaw‐opening muscles was examined in the lower brainstem of the rat by using retrograde and anterograde labeling techniques. First, Fluorogold, a fluorescent retrograde tracer, was injected into the dorsolateral or ventromedial division of the trigeminal motor nucleus, each of which contains motoneurons innervating the jaw‐closing or jaw‐opening muscles, respectively. Second,Phaseolus vulgaris‐leucoagglutinin, an anterograde tracer, was injected into each of the lower brainstem sites, where clusters of retrogradely labeled premotor neurons had been seen in the first set of experiments. Third, after injection of the anterograde tracer into a lower brainstem site, followed by injection of the retrograde tracer cholera toxin B subunit into a masticatory muscle, termination of anterogradely labeled axons onto retrogradely labeled motoneurons was confirmed with the aid of a confocal laser‐scanning microscope. It was found that the premotor neurons distributed in the mesencephalic trigeminal nucleus, medial part of the parabrachial region, supratrigeminal region, and dorsal parts of the principal sensory, oral spinal and interpolar spinal trigeminal nuclei project preferentially to the dorsolateral division of the trigeminal motor nucleus, whereas those in the lateral part of the parabrachial region, intermediate parts of the principal sensory, oral spinal and interpolar spinal trigeminal nuclei, and alpha part of the gigantocellular reticular nucleus project preferentially to the ventromedial division of the trigeminal motor nucleus. The dorsal and lateral parts of the medullary reticular formation and the medullary raphe nuclei contain premotor neurons of both types. Group k motoneurons, a cluster of trigeminal motoneurons that innervate the tensor tympani muscle, receive projection fibers predominantly from the dorsolateral part of the oral pontine reticular formation. © 1995 Wil

ISSN:0092-7317    

DOI:10.1002/cne.903560407

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractCA3 pyramidal neurons were stained with biocytin during intracellular recording in rat hippocampus in vivo and reconstructed using a computer‐based system. The in vivo CA3 neurons were characterized primarily according to their proximity to the hilus and secondarily with respect to the septotemporal location. Neurons measured in CA3a (n = 4), in CA3b (n = 4), and in posterior/ventral locations (n = 3) had the greatest dendritic lengths (19.8, 19.1, and 26.8 mm on average, respectively). Cells closer to the hilus showed much shorter dendritic lengths, averaging 10.4 mm for CA3c neurons (n = 4) and 11.6 mm for zone 3 neurons (n = 2). Half of the cells showed more than one major apical dendrite, and dendritic trees were highly variable even within CA3 subregions. The mean electrotonic length for these cell groups averaged between 0.30 λ (CA3c) and 0.45 λ (posterior /ventral), assuming a constant specificmembrane resistivity of 60 KΩ‐CM2. These CA3 neurons form a database of reconstructed neurons for further morphometric and electrical modelling studies. The large degree of variability between individual CA3 neurons indicates that both dendritic and electrical properties should be specifically calculated for each cell rather than assuming a “typical” morphology. © 1995 Wile

ISSN:0092-7317    

DOI:10.1002/cne.903560408

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe afferent and efferent cortical projections of the dorsal lateral geniculate nucleus (GLD) of adult specimens of the turtleEmys orbiculariswere investigated after intraocular or intracortical injections of horseradish peroxidase (HRP), and the distribution of gamma aminobutyric acid (GABA) immunoreactivity in the nucleus was carried out by immunocytochemical techniques, both techniques being combined with light and electron microscopy. In addition, some specimens were prepared for double‐labeling of HRP and GABA immunoreactivity, and additional samples impregnated by a rapid Golgi technique. On purely morphological grounds, four types of neurons can be distinguished by light microscopy: two types of large cells in the cell plate which project to the cortex, and two types of smaller cells in the neuropil and optic tract which do not. The small cells are consistently GABA‐immunoreactive, while the former are, with extremely rare exceptions, immunonegative for GABA. The supposition that the small neurons of the neuropil are interneurons is supported by electron microscopic observations; these strongly GABA‐immunoreactive cells have large plicated nuclei surrounded by a thin layer of cytoplasm poorly endowed with organelles. The dendrites of these cells may contain pleomorphic synaptic vesicles (DCSVs) and appear to be presynaptic to other dendritic profiles. These DCSVs are occasionally contacted by GABA‐immunoreactive axon terminals, and more frequently by retinal terminals consistently immunonegative for GABA. The latter, frequently organized in glomeruli, also make synaptic contacts with immunonegative dendrites arising from corticopetal neurons of the cell plate. Two major categories of GABA‐immunoreactive axon terminals can be distinguished, and we are led to the conclusion that one of these represents an intrinsic GABAergic innervation of the GLD, while the second is tentatively interpreted as an extrinsic source of GABA to the nucleus, possibly from ventral thalamic structures. The fine structure of the dorsal lateral geniculate nucleus of Emys orbicularis thus shows many similarities with that of mammals. © 1995 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903560409

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe pharmacological and physiological properties of ligand‐gated ion channels are dependent on their subunit composition; spontaneously occurring changes in subunit composition during neuronal development may result in dramatic functional differences between embryonic and adult forms of the receptor complex. In the present study, in situ hybridization with antisense cRNA probes was used to examine the subunit composition of the γ‐aminobutyric acidA/benzodiazepine (GABAA/BZ) receptor in the developing inferior olivary complex. This receptor is thought to be a pentameric chloride channel comprised of selected α, β, γ, δ, and ρ subunits, the majority of which have several isoforms: α1−6, β1−4, γ1−4and ρ1, 2. Among the 13 subunit variants present in the mammalian central nervous system, α2−5β3, and γ1, 2mRNAs are expressed at significant levels in the inferior olivary complex. Two clearly different temporal patterns of GABAA/BZ receptor subunit mRNA expression were observed: The expression of α3, α5, β3, and γ2mRNAs was at a peak during embryonic and early postnatal development followed by rapid down‐regulation thereafter. Conversely, α2, α4, and γ1mRNA expression was very low or absent during early development, and a pronounced increase was observed at the end of postnatal week 1. These studies suggest that there are developmental changes in the subunit composition of the GABAA/BZ receptor in inferior olivary neurons. These changes in subunit expression, which occur during a period of major alterations in afferent and efferent synaptic connections, may subserve a change in the role of GABA from its function as a neurotrophic factor to that of an inhibitory neurotr

ISSN:0092-7317    

DOI:10.1002/cne.903560410

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractPolysialylated neuronal cell adhesion molecule (PSAqN‐CAM) is a cell surface molecule associated with neurons that undergo changes in configuration or spatial translocation. In both cases, this molecule is thought to reduce the adhesivity of these cells or of their processes, which can thereby insinuate themselves into the existing parenchyma. We used a monoclonal antibody specific to PSA to offer what we believe is the first account of the distribution of PSA‐N‐CAM in the adult songbird brain. This antibody stained a diversity of cell classes and processes, as follows: (1) a subset of ventricular zone cells; (2) migrating cells thought to be neuroblasts; (3) a subset of differentiated neurons; (4) some brain surface astrocytes; (5) some tanycytes; (6) the neuropil of some regions; (7) some axonal fibers; and (8) possibly some synapses. Our results demonstrate also, for the first time, the wide distribution of a very numerous population of migrating cells in the telencephalon and the seasonal regulation of PSA‐Nq‐CAM expression in a part of the adult brain known to undergo seasonal changes in cell recruitment and function. However, we did not find PSA‐N‐CAM associated with young migrating cells in the high vocal center (HVC), nor was there PSA‐N‐CAM in the robust nucleus of the archistriatum (RA), which is known to receive new axonal endings from HVC. In these instances spatial translocation may occur with the assistance of other surface molecules. © 19

ISSN:0092-7317    

DOI:10.1002/cne.903560411

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY