摘要:

AbstractNitric oxide has recently been implicated as a neurotransmitter, and may modulate synaptic transmission, cerebral blood flow, and neurotoxicity. NADPH diaphorase histochemistry has been shown to be a reliable marker for nitric oxide synthase, the enzyme that synthesizes nitric oxide, in the nervous system. Because monoaminergic neurons frequently contain co‐transmitters, we examined whether these cells also exhibit NADPH diaphorase activity. Frozen sections from postnatal and adult rat brains were stained for NADPH diaphorase activity and either serotonin‐like immunoreactivity or tyrosine hydroxylase‐like immunoreactivity. Numerous neurons in the mesopontine serotoninergic cell groups (including the caudal linear, dorsal, median, supralemniscal, and pontine raphe nuclei) contained both serotonin‐like immunoreactivity and NADPH diaphorase activity. Within the dorsal raphe nucleus, approximately 70% of the serotoninergic neurons in the medial subnuclei displayed NADPH diaphorase activity, while less than 10% of the serotoninergic neurons in the lateral subnuclei were doubly labeled. Retrograde labeling with fluorescent microspheres indicated that many raphe‐cortical neurons contained NADPH diaphorase activity. No NADPH diaphorase activity was detected in serotoninergic neurons in the medullary nuclei (including the raphe magnus, raphe pallidum, and raphe obscurus). Only a small proportion of tyrosine hydroxylase‐like immunoreactive neurons in the periaqueductal gray, rostral linear nucleus, and rostrtrodorsal ventral tegmental area contained NADPH diaphorase activity. Tyrosine hydroxylase‐like immunoreactive neurons in the substantia nigra, locus coeruleus, hypothalamus, olfactory bulb, and dorsal raphe nucleus did not contain detectable NADPH diaphorase activity. The observation that many mesopontine (but not medullary) serotoninergic neurons contain NADPH diaphorase activity suggests that these neurons may release both serotonin and nitric oxide. © W

ISSN:0092-7317    

DOI:10.1002/cne.903320402

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe rod dominated rodent retina is the preferred tissue for in vitro studies of mammalian retinal physiology and pharmacology. The rod pathway through the rat retina was investigated, therefore, in order to find out whether its organization follows the mammalian “plan.” AII‐amacrine cells of the rat retina were injected with Lucifer Yellow to characterize the morphology of this bistratified interneuron of the rod pathway. When sections or whole mounts of the rat retina were stained with antibodies against the calcium binding protein parvalbumin (PV), two different amarcine cell types were labeled: the AII‐amacrine cell and a widefield amacrine cell. They occur at a ratio of 12:1. Weak label was also observed in ganglion cells. The density of PV‐labeled AII‐cells decreases from approximately 7,000 cells/mm2in upper central retina to 2,000 cells/mm2in peripheral retina. Their cell bodies form a regular mosaic, and the dendritic arbors of three neighbouring AII‐amacrine cells overlap (coverage of 3). © W

ISSN:0092-7317    

DOI:10.1002/cne.903320403

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractTwo immunocytochemical markers were used to label the rod pathway of the rat retina. Rod bipolar cells were stained with antibodies against protein kinase C and AII‐amacrine cells with antibodies against parvalbumin. The synaptic circuitry of rod bipolars in the inner plexiform layer (IPL) was studied. Rod bipolar cells make approximately 15 ribbon synapses (dyads) in the IPL. Both postsynaptic members of the dyads are amacrine cells; one is usually the process of an AII‐amacrine cell and the other one frequently provides a reciprocal synapse. No direct output from rod bipolar cells into ganglion cells was found. AII‐amacrine cells make chemical output synapses with cone bipolar cells and ganglion cells in sublamina a of the IPL. They make gap junctions with cone bipolar cells and other AII‐amacrine cells in sublamina b of the IPL. The rod pathway of the rat retina is practically identical to that of the cat and of the rabbit retina. It is very likely that this circuitry is a general feature of mammalian retinal organization. © Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903320404

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractWe have examined the morphology of astrocytes and the arrays they form in two situations, in retinas from which ganglion cells and blood vessels have been caused to degenerate, and in vitro. These observations were made to test whether the regularity of the spacing of astrocytes within normal central nervous tissue results from interaction among astrocytes, or from interaction between astrocytes and other elements of that tissue. Both in the partially degenerated cat retina, and in cultures of astrocytes from neonatal rat cortex, astrocytes make and maintain contact with neighbouring astrocytes, yet space their somas apart, giving regularity to the arrays. These results support the hypothesis that the regularity observed in arrays of astrocytes in intact tissue results from an interaction among astrocytes, independent of neighbouring structures, and lead us to suggest that the cell‐cell interactions involved in contact spacing serve to distribute astrocytes through the central nervous system, and may, in other tissues, underlie the formation of epithelia. © Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903320405

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractCarbohydrate differentiation antigens are known to display specific patterns of expression during mammalian development and are thought to participate in significant morphogenetic events. In the present study, two monoclonal antibodies that react with a novel carbohydrate differentiation antigen (CDA‐3C2) were used to analyze, by light microscopy, the spatiotemporal distribution of this unique high molecular weight antigen during embryogenesis in the rat. Correlative analysis of the development of peripheral neural structures, in which CDA‐3C2 was expressed, was carried out with an anti‐neurofilament antibody. Enzymatic digestion, combined with Western blots, reveal that the CDA‐3C2 epitope is a carbohydrate which is carried on a high molecular weight glycoprotein with a mass of greater than 1 million Daltons. Characteristic of carbohydrate antigens, immunoreactivity was found in several distinct cellular patterns: only along the apical border of cells, along lateral and basal membranes of cells, and extracellular‐like staining in the mesenchyme. During neurulation, CDA‐3C2 showed differential staining in the ectoderm, distinguishing lateral from neural regions. Following closure of the neural tube, there was a striking specificity of expression of CDA‐3C2 in the periphery, found almost exclusively in olfactory and otic epithelial structures. While CDA‐3C2 is found in placode‐derived tissues that subserve sensory transduction, it appears to be primarily associated with the supportive cells (and their secretions) in both otic and olfactory regions and less so with the sensory cells. The data suggest that a unique carbohydrate antigen on a large macromolecule may play a role in neurulation and/or morphogenesis of the placode‐derived otic and olfactory structures

ISSN:0092-7317    

DOI:10.1002/cne.903320406

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractA carbohydrate differentiation antigen (CDA‐3C2) exhibits a highly specific and restricted pattern of expression during rat embryogenesis. In the periphery of the embryo, this antigen is associated transiently with the lateral ectoderm but is retained only in the olfactory and otic epithelium throughout morphogenesis. At the light microscopic level, CDA‐3C2 immunoreactivity appears mostly along cell periphery and in the extracellular matrix. The aim of the present study was to determine the specific cellular and subcellular distribution of CDA‐3C2 in vivo in order to identify potential sites of cellular and tissue function of the antigen during embryogenesis. There was a strikingly similar subcellular distribution of CDA‐3C2 in the developing otic and olfactory systems, found mostly along cell membranes, microvillar projections and acellular secretions of the epithelium. Mature sensory components of the epithelia were not immunoreactive, whereas supportive cells and their secreted structures were densely stained. The highly coincident nature of CDA‐3C2 in both sensory epithelia suggests that this carbohydrate epitope, and possibly its carrier macromolecule, participate in a morphogenetic function common to these two sensory epithelia. © Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903320407

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractPlasticity following deafferentation has been repeatedly demonstrated in topographic sensory maps in the mammalian brain. In this paper we investigated the developmental plasticity of the fractured somatotopic map found in the tactile regions of the rat cerebellum. At various stages of postnatal development between postnatal days 1 and 30, we cauterized the infraorbital branch of the trigeminal nerve, which innervates the upper lip, furry buccal pad, and vibrissae that are represented within cerebellar folium crus IIa. The organization of the crus IIa map was then examined 2 to 3 months after denervation. We found that tactile receptive fields had reorganized throughout the denervated area but maintained a fractured somatotopy. Comparison of the reorganization in different animals showed that the denervated upper lip region was consistently and predominantly replaced by representation of the upper incisors. Analysis of evoked field potentials revealed an alteration, in denervated animals, of the response of the granule cell layer to brief tactile stimulation. This response in normal animals consists of two components at different latencies. Animals lesioned later in development were less likely to have the short latency component. This result suggests a difference in the developmental sensitivity of different cerebellum‐related pathways to nerve lesion

ISSN:0092-7317    

DOI:10.1002/cne.903320408

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe spatial distributions and dendritic branching patterns of chemically identified subpopulations of striatal intrinsic neurons, defined by immunoreactivity for choline acetyltransferase (ChAT), neuropeptide Y or parvalbumin, were studied in relation to patch and matrix compartments of rat neostriatum. ChAT‐immunoreactive cells and fibers showed an uneven pattern of distribution in the striatum. ChAT immunoreactivity was higher in the dorsolateral part and lower in the ventromedial part of the striatum. This regional gradient pattern is the inverse of the overall pattern of calbindin D28kimmunoreactivity. However, in small regions close to the lateral ventricle and globus pallidus, areas containing fewer ChAT‐immunoreactive cells and fibers coincided with those containing low calbindin D28kimmunoreactivity. Neuropeptide Y immunoreactivity was uniform in the neostriatum. Certain neuropeptide Y cells (about 20%) were also immunoreactive for calbindin D28k, indicating that at least a small population of calbindin D28k‐immunoreactive cells are medium aspiny cells. Parvalbumin immunoreactivity was not uniform in the striatum. A higher density of parvalbumin immunoreactivity was found in the neuropil in lateral and caudal parts than in the medial part. Small regions with weaker parvalbumin‐immunoreactive neuropil partially corresponded to calbindin D28kpoor patches. Larger cells immunoreactive for parvalbumin were preferentially located in lateral and caudal parts of the striatum.Cells immunoreactive for ChAT, neuropeptide Y or parvalbumin showed basically similar distribution patterns in relation to the patch and matrix compartments. Most stained cells were located in the matrix, but some were located at the borders of patches and a few were inside patches. Most primary dendrites of stained cells in the matrix or patches remained confined to these compartments, but cells on the borders invariably extended dendrites into both compartments. The striatal intrinsic neurons form chemically differentiated neuronal circuits within the matrix, and the patches and those whose dendrites cross the borders may contribute to associational interconnections between the two compartments, unlike the spiny projection neurons whose dendrites are confined to one or the other compartment. © Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903320409

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.903320401

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY