摘要:

AbstractBranching projections from pedunculopontine and laterodorsal tegmental nuclei to different thalamic targets were studied by means of a double retrograde tracing technique. The results show a topographic distribution of mesopontine neurons projecting to different thalamic targets. In addition, the present data demonstrate that a small percentage (≤ 5%) of mesopontine neurons projecting to the intralaminar nuclei or to the rostral pole of the reticular nucleus innervate both these areas by means of branching axons. By contrast, a large number of mesopontine neurons projecting to the sensorimotor thalamic nuclei send axon collaterals to the caudal part of the reticular nucleus. The present findings support the hypothesis of an inhomogeneity of different sectors of the thalamic reticular nucleus. Thus, this nucleus can be differentiated into two functional areas, in accordance with their connections with functionally different cortical fields and thalamic districts. The possibility that these two areas of the thalamic reticular nucleus subserve different mechanisms during sleep phenomena is discussed. © 1993 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903360402

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe expression of the neural cell adhesion molecule (NCAM) and distinct carbohydrate groups by cells of the taste buds of the rat vallate papilla was investigated by immunohistochemical and biochemical techniques. We employed antibodies against (1) the extracellular (mAb 3F4) and cytoplasmic (mAb 5B8) portions of the NCAM polypeptide, (2) the highly sialylated form of NCAM (mAb 5A5), (3) carbohydrate epitopes associated with glycosylated NCAM forms in the rat (mAb 2B8) or frog (mAb 9‐OE) olfactory system, and also (4) the Lewisbblood group carbohydrate epitope (mAb CO431). NCAM mRNA was demonstrated by polymerase chain reaction (PCR) in samples of the vallate papilla, suggesting the presence of NCAM in cells of the taste buds. Antibodies against NCAM (mAbs 3F4 and 5B8) recognized a subset (about 20%) of cells within the vallate taste buds; fibers of the glossopharyngeal nerve, including those innervating the gustatory epithelium, were NCAM immunoreactive. Taste bud cells did not express polysialic acid (mAb 5A5), but mAb 5A5 immunoreactivity was observed on fibers of the IXth nerve, including a few that entered the taste buds. All or nearly all of the cells within the vallate taste buds were immunoreactive to mAb 2B8, whereas mAbs 9‐OE and CO431 reacted with subsets of cells. The carbohydrates recognized by mAbs 2B8 and 9‐OE were also abundantly expressed in the ducts and acini of the lingual salivary glands. Bilateral crush of the IXth nerve resulted in the loss of expression of all of these molecules from the gustatory epithelium. If cells of the taste bud express NCAM during their final stage(s) of differentiation, then NCAM could play a role(s) in the growth of gustatory axons toward their target epithelial cells and in the recognition between the nerve fibers and mature taste receptor cells, or among the taste bud cells themselves. © 1993 Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903360403

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractTaste buds consist of approximately 100 taste cells, including three morphological types of short receptor cells which synapse on the peripheral gustatory nerves. Some of the receptor cells produce neural cell adhesion molecule (NCAM), which may play a role in formation of specific connections in this system. Antibodies directed against different forms of NCAM were utilized in an attempt to define not only the distribution, but also the type of NCAM within taste buds.Within each taste bud approximately 10% of the taste cells exhibit abundant immunoreactivity for 180 kD (ld) or 140 kD (sd) forms of NCAM (i.e., those with an intracellular domain) along virtually the entire surface of the cell. Ultrastructural analysis reveals that these abundantly immunoreactive taste cells are of the intermediate morphological type, although not all of the intermediate taste cells within any bud are immunoreactive. In addition, the ultrastructural studies show that punctate (ld/sd) NCAM‐immunoreactivity occurs on the membranes of taste cells and nerve fibers throughout each taste bud. The embryonic form of NCAM (E‐NCAM), rich in polysialic acid residues, is present only in association with nerve fibers and other unidentified elongate, thin profiles of a few taste buds.The nerve plexus beneath the gustatory epithelium is also rich in NCAM‐immunoreactivity. These fibers occasionally reveal immunoreactivity indicative of only the 120 kD (ssd) form of NCAM, typical of glial cells. © 1993 Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903360404

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe sympathetic innervation of the mammalian cornea is thought to play an important role in the regulation of epithelial ion transport, mitogenesis, and wound healing following corneal injuries. Anatomically, the three‐dimensional organization and relative density of corneal sympathetic innervation in many species remains inadequately described. In the present study, the sympathetic innervation of five different mammals (guinea pig, rat, mouse, hamster, and human) was studied in corneas sectioned parallel to the main axis of fiber orientation by labeling the fibers immunohistochemically with antiserum against tyrosine hydroxylase and an avidin‐biotin‐diaminobenzidine technique. The results showed that each species displayed a distinctive pattern and density of tyrosine hydroxylase immunoreactive (TH‐IR) corneal innervation that was unique to that species. The overall level of TH‐IR innervation was highest in the guinea pig, moderate in the human, hamster, and rat, and lowest in the mouse. In all species examined, TH‐IR nerves were most numerous in the corneoscleral limbus where they either formed intimate associations with blood vessels or coursed through the connective tissue matrix apparently unrelated to vascular elements. Other TH‐IR nerves entered the cornea proper in radially directed stromal nerve bundles to give rise to subepithelial plexuses of varying complexity. Occasional intraepithelial penetrations were observed in the guinea pig, human, and rat. Removal of the superior cervical ganglion resulted in the total loss of TH‐IR staining from guinea pig and hamster corneas and in the substantial but incomplete loss of TH‐IR staining from rat and mouse corneas, thus demonstrating their predominantly sympathetic origin. Combined sympathetic and sensory ocular denervation in the rat eliminated almost all corneal and limbal TH‐IR immunostaining, thus suggesting a minor TH‐IR sensory component in this species. In agreement with this conclusion, small numbers of TH‐IR sensory neurons and an abundance of TH‐IR fibers were observed in the trigeminal ganglia of the rat and guinea pig. Removal of the rat main ciliary ganglion resulted in the loss of additional TH‐IR fibers from the chamber angle and iris, thereby confirming a partial parasympathetic contribution to the rat iridial TH‐IR innervation. Following unilateral removal of the superior cervical ganglion in rats and guinea pigs, the contralateral cornea contained increased numbers of TH‐IR nerves, suggesting an upregulation of tyrosine hydroxylase (TH) expression in some contralateral axons. In summary, these data have shown pronounced interspecies differences in the organization and density of the mammalian corneal TH‐IR innervation that may reflect species‐specific variation in the level of sympathetic control over select aspects of corneal

ISSN:0092-7317    

DOI:10.1002/cne.903360405

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractAntibodies specific to the neural cell adhesion molecule (NCAM‐total), the 180 × 103My component of NCAM (NCAM‐180) and polysialic acid (PSA) were used in immunohistochemistry and Western blots to detect the spatiotemporal dynamics of these molecules in development and regeneration of the retinotectal system ofPleurodeles waltl. NCAM‐total and NCAM‐180 are continuously expressed in the retina, optic nerve, and tectum of the developing and adult salamander. This is also found for the 140 × 103My component of NCAM in Western blots of the retina. In the larval retina, PSA is present in the inner plexiform layer (IPL) and a few cells in all nuclear layers. At metamorphosis, PSA expression in the retina strongly increases in the layer of cone photoreceptor somata. Several cells in the inner nuclear layer and Muller cell processes also begin to express PSA. This pattern persists into adulthood. The optic nerve and the tectum are strongly PSA‐immunoreactive throughout development. In the adult optic nerve and optic fiber pathway in the brain, PSA expression is selectively downregulated. In the crush‐lesioned adult optic nerve, regenerating fibers are NCAM‐180‐positive but PSA‐negative. This demonstrates a molecular difference between growing nerve fibers ofPleurodelesin development and in regeneration. PSA regulation is closely correlated with metamorphosis, thus suggesting that PSA expression may be under hormonal control. Some aspects of PSA and NCAM isoform expression patterns in the retinotectal system of salamanders differ considerably from that of other vertebrates. The substained expression of NCAM isoforms in adult salamanders might be due to secondary simplification (paedomorphosis). ©

ISSN:0092-7317    

DOI:10.1002/cne.903360406

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe effect of deafferentation on the neuropeptides substance P (SP), calcitonin generelated peptide (CGRP), somatostatin (SS), and cholecystokinin (CCK) in the lumbar dorsal horn of the adult rat was examined by the indirect immunohistochemical method. Deafferentation was induced by injecting the sciatic nerve of anesthetized rats with proteolytic enzymes (20 mg pronase), which cause selective death of the nerve's ganglion cells and degeneration of their terminal arborization in the spinal cord. The density of immunolabel of each peptide was determined by using a computerized densitometry analysis system in two animal groups, i.e., short‐term (10–13 days after injection) and long‐term (4–9 months). In both groups, the deafferentation produced a significant ipsilateral depletion of CGRP, SP, CCK, and SS immunoreactivity. This depletion was limited to the area occupied by the sciatic terminals in the dorsal horn. In the long‐term group, the loss of CGRP and SP staining was significantly less than that in the short‐term animals, thus indicating partial recovery. A similar, but not statistically significant, trend was observed for CCK and SS. The large decrease in CGRP and SP seen in short‐term animals reflects the large contribution of the sciatic nerve to the lumbar dorsal horn. The partial recovery of peptides demonstrates the plasticity of the nervous system and may parallel sprouting of primary afferents from other nerves, such as the saphenous nerve, as we have demonstrated in previous studies. © 1993 W

ISSN:0092-7317    

DOI:10.1002/cne.903360407

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractNeuropeptide FF (F8Famide, FMRFamide‐like, or morphine modulating peptide) immunoreactivity was localized by light and electron microscopy in the hypothalamo‐neurohypophyseal system of Wistar and Brattleboro rats. In Wistar rats neuropeptide FF was present in part of the magnocellular neurones of the paraventricular and supraoptic nuclei in which it was coexpressed with vasopressin. Neuropeptide FF containing fibers were present in the paraventricular and the supraoptic nuclei, and in the central part of the neural lobe. At the electron microscopic level, neuropeptide FF containing nerve terminals in the neural lobe formed synaptoid contacts exclusively with pituicytes. No neuropeptide FF containing neurovascular contacts or contacts with other neuronal structures were observed.In contrast with Wistar rats, neuropeptide FF was almost completely absent in cell bodies of the paraventricular and supraoptic nuclei, and in fibres of the neural lobe in Brattleboro rats. Only a few solitary cells could be observed in these structures. The present results demonstrate that neuropeptide FF coexists with vasopressin within the hypothalamo‐neurohypophyseal system. As we did not observe neuropeptide FF containing neurovascular contacts, neuropeptide FF containing nerve terminals probably have a local function within the neural lobe. Neuropeptide FF may be involved in the modulation ofoxytocin and vasopressin release, with the pituicyte as an intermediate cell. © 1993 Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903360408

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractGonadotropin‐releasing hormone (GnRH) constitutes a family of neuropeptides found throughout the vertebrates. Although a GnRH‐like peptide has also been isolated from yeast (α‐mating factor), the presence of GnRH has not been clearly demonstrated in inverterate phyla. In this study, we tested the hypothesis that GnRH‐like peptides are present and functional in the central nervous system (CNS) of the gastropod mollusc,Helisoma trivoluis.The presence of a GnRH‐like peptide was examined by three methods: (1) in immunofluorescence studies with four different antibodies generated against several GnRH peptides, select neurons and putative neurosecretory cells were specifically and consistently labelled throughout the CNS; (2) reverse‐phase high performance liquid chromatography (HPLC) and radioimmunoassay (RIA) analysis revealed a GnRH‐like factor which co‐migrates with mammalian (m)GnRH; and (3) in bioactivity experiments, extracts ofHelisomatrivolvis CNS mimicked GnRH in stimulating gonadotropin release from dispersed goldfish pituitary cells in static culture.Two functional assays were carried out to examine the potential biological roles of GnRH‐like peptides inHelisoma.(1) Intracellular recordings of left‐parietal and visceral ganglion neurons revealed diverse electrophysiological responses to mGnRH. These effects were attenuated by a mGnRH antagonist. (2) Addition of mGnRH arrested neurite outgrowth in a subpopulation of dissociated embryonicHelisomaneurons in culture. Taken together, these results strongly suggest that a mGnRH‐like peptide is an important neuropeptide inHelisoma. A hypothesis is presented that GnRH‐like peptides may be ancient factors that are conserved both structurally and functionally in the evolution of animals

ISSN:0092-7317    

DOI:10.1002/cne.903360409

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe central organization of antennular motoneurons in the brain of the spiny lobster,Panulirus argus, was analyzed by combining biocytin backfills with serial reconstructions of the antennular nerves and the brain. Eighty‐nine to 99 antennular motoneurons occur in each hemibrain. The somata of the motoneurons are distributed in a consistent pattern in two complex soma clusters, the ventral paired mediolateral cluster of the deutocerebrum and the dorsal unpaired median cluster of the tritocerebrum. The motoneurons arborize ipsilaterally in the lateral and median antennular neuropils and the tegumentary neuropil. The backfills indicate a minimum of five morphological types of motoneurons with different arborization patterns. The innervation pattern of the motoneurons, together with previously reported innervation patterns of antennular sensory afferents, suggest that the lateral antennular neuropil is a lower motor center driving local antennular reflexes in response to chemical and mechanical stimulation of the antennule, whereas the median antennular neuropil is a lower motor center for equilibrium responses. © 1993 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903360410

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractHereditary absence of the corpus callosum (CC) provides an ideal experiment of nature for exploring mechanisms of axon guidance. In this study the prenatal development of CC axons in the acallosal mouse strains BALB/cWah1 and 129/ReJ or J was compared with normal hybrid mice by using the lipophilic dyes Dil and DiA. A few l/LnJ mice were also examined. The time of emergence and growth rate of CC axons from four cortical regions (frontal, parietal, temporal, occipital) were normal in acallosai strains. Their CC axons arrived at midplane on schedule but then often looped back to form the longitudinal Probst bundle. The frequency of formation of the Probst bundle was highest for axons from frontal cortex, which arrived at midplane first, and lowest for occipital axons, which arrived last. Once a few CC axons found a path to the other side via the hippocampal commissure, those that arrived later then crossed relatively normally. Some axons from the Probst bundle also managed to traverse midine in this manner. When no CC axons crossed, almost all of them entered the Probst bundle and eventually left it within a few hours to proceed in the ipsilateralwhite matter, never turning back toward midplane. Growth cones approaching midplane ipsilaterally and those that had crossed midline and entered contralateral white matter, as well as CC axons in the Probst bundle, expressed a normal range of size and complexity. These results demonstrate that the problem with callosal agenesis resides not in the cells of origin or the axons or growth cones themselves but in the Substrates of axon guidance at the midsagittal plane. © 1993 Wiley‐Liss, I

ISSN:0092-7317    

DOI:10.1002/cne.903360411

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY