摘要:

AbstractRetinal amacrine cells can be divided into subgroups on the basis of morphological properties and chemical content. It is likely that these subgroups have specific connections and serve unique functional roles within the inner plexiform layer. In the present study we show that immunoreactivity to neuropeptide Y (NPY) identifies a group of amacrine cells (165,000–170,000) whithin the adult cat retina. This is the largest group of peptide‐containing amacrine cells identified to date in the cat retina. These neurons have small cell bodies and are regularly spaced at all regular spacing, suggests that these neurons form a specific subgroup of the amacrine cell class and are likely to serve a unique role in the transfer of visual information through the inner plexiform layer. © 1994 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903460402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractElectrophysiological and behavioral studies have described modulation of nociception by vagal afferent fibers. The objectives of this study were to (1) use Fos‐like immunoreactivity as a marker for neuronal activity to examine populations of neurons in the spinal cord that are activated by a noxious heat stimulus, (2) determine whether heat‐evoked Fos‐like immunoreactivity can be modulated by vagal afferent stimulation, and (3) determine whether vagallymediated effects on heat‐evoked Fos‐like immunoreactivity can be blocked by intrathecally administered serotoninergic receptor and α‐adrenergic receptor antagonists.Neurons demonstratiring Fos‐like immunoreactivity were located in the ipsilateral superficial and deep dorsal horn laminae extending from the caudal L3through the rostral L6region of the spinal cord. Stimulation of the right cervical vagus nerve attenuated significantly (42%) heat‐evoked Fos‐like immunoreactivity in the superficial laminae. The reduction in Fos‐like immunoreactivity by vagal stimulation was abolished by intrathecal administration of methysergide, a nonselective serotoninergic receptor antagonist, but not by phentolamine, a nonselective α‐adrenoceptdr antagonist. These results suggest that vagal afferent modulation of spinal nociceptive transmission is mediated, at least in part, by serotonin receptors.

ISSN:0092-7317    

DOI:10.1002/cne.903460403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe mammalian cerebellum is built around an array of parasagittal bands of Purkinje cells that can be demonstrated by immunocytochemical staining for the differentiation antigen zebrin II. Climbing and Mossy fiber afferents also terminate in bands, and the afferent terminal fields and the Purkinje cell bands are aligned. The convergence of mossy and climbing fiber pathways onto the Purkinje cells, which are the sole output of the cerebellar cortex, is a characteristic feature of cerebellar circuitry. Previous studies showed that when both afferent pathways are activated synchronously there develops a long‐term depression of synaptic efficacy at the parallel fiber‐Purkinje cell synapse. Two second messenger pathways mediate long‐term depression: one involves diacylglyceroland protein kinase C, and the other involves nitric oxide that is generated by a nitric oxide synthase. We have studied the distribution of nitric oxide synthase in the adult Mouse cerebellum by using nicatinamide adenine dinucleotide phosphate (NADPH)‐diaphorase histochemistry. NADPH‐diaphorase activity is found mainly in the granule and basket cells. Within the granular layer NADPH‐diaphorase activity is expressed nonuniformly patches of granule cells and synaptic glomeruli. The patches are yseen in all lobules, are reproducible from individual to individual, and are topographically ordered with respect to the Purkinje cell compartments as revealed by usinganti‐zebrin IIimmunocytochemistry. These data imply that nitric oxide‐dependent, long‐term depression may only involve a subset of mossy fiber/granule cell projections, and that one role for nitric oxide may be to refine cerebellar receptive fields. © 19

ISSN:0092-7317    

DOI:10.1002/cne.903460404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractCalretinin is a calcium‐binding protein of the EF‐hand family. It has been previously identified in particular cell types of adult guinea pig, rat, and chinchilla inner ear. Development of calretinin immunoreactivity in the mouse inner ear was investigated from embryonic day 13 (E13) to the adult stage. In the adult mouse vestibule, calretinin immunoreactivity was present in the same structures as described for the rat and guinea pig: the population of afferent fibers forming calyx units and small number of ganglion neurons. The earliest immunoreactivity was found at E17 in vestibular hair cells (VHCs), then, at E19, in afferent fibers entering the sensory epithelia and in rare ganglion neurons. At postnatal day 4 (P4), a few vestibular nerve fibers and ganglion neurons were reactive. From this stage until P14, immunoreactivity developed in the calyx units and disappeared from VHCs. At P14, immunostaining was adult‐like. In the adult mouse cochlea, immunoreactivity was present in the same cell populations as described in the rat: the inner hair cells (IHCs) and most of Corti's ganglion neurons. Calretinin immunoreactivity appeared at E 19‐P0 in IHCs and ganglion neurons of the basal turn. At P1, outer hair cells (OHCs) of the basal turn were positive. Calretinin immunoreactivity then appeared in IHCs, OHCs, and ganglion neurons of the medial turn, then of the apical turn. At P4, all IHCs and OHCs and most of the ganglion neurons were immunostained. Immunoreactivity gradually disappeared from the OHCs starting at P10 and, at P22, only IHCs and ganglion neurons were positive. The sequences of appearance of calretini, n were specific to each cell type of the inner ear and paralleled their respective maturation. Calretinin was transiently expressed in VHCs and OHCs. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903460405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractA large number of neurotransmitters and neuropeptides are concentrated in the dorsal horn of the spinal cord, Where they interact in a complex manner and modulate sensory mechanisms. Most studies are carried out in the rat, and little is known of other species. It is relevant to study mammals with a more complex central nervous system, because pain mechanisms are central in both human and veterinary medicine. Immunoreactivity for neuropeptide FF, an amidated octapeptide originally isolated from bovine brain, was found immunocytochemically at all levels of porcine spinal cord. In contrast to other species studied so far, the peptide immunoreactivity in porcine spinal cord was confined to the intermediolateral gray matter, especially to the intermediolateral cell column and lamina X of the gray matter. This distribution was remarkably different from that of substance P, proenkephalin A‐derived peptides, thyrotropin‐releasing hormone, serotonin, and neuropeptide Y. Pharmacologic administration of neuropeptide FF alters behavior in assays for analgesia. The distribution of neuropeptide FF immunoreactivity as revealed by this study suggests that there may be marked species differences in the distribution and function of the peptide. © 1994 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903460406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe intrabulbar associational system (UAS) originates from tufted cells whose axons terminate in the internal plexiform layer (IPL) on the opposite side of the same olfactory bulb. The postsynaptic targets of the IAS are unknown. Subpopulations of tufted cells contain different neuropeptides and transmitters but it is not known if tufted cells forming the IAS are homogeneous with respect to neurotransmitters. Therefore, the goals of the present study were to identify thepostsynaptic targets of the IAS and to determine the major transmitter in this intrabulbar circuit.Biocytin anterograde tracing revealed that the axons of superficially situated tufted cells coursed directly to the IPL where they turned abruptly to run ventrally and dorsally to terminate in the IPL on the opposite side of the olfactory bulb. WGAapoHRP‐Au retrograde tracing combined with immunohistochernistry for CCK revealed that all tufted cells retrogradely labeled by WGAapoHRP‐Au injection in the IPL were immunoreactive for CCK Anterograde transport of biocytin combined with postembedding immunocytochemical goldlabeling for GABA demonstrated that labeled IAS axons terminate predominantly, if not exclusively, on GABAergic granule cell dendrites in the IPL.These results confirm that the IAS arises from tufted cells and is topographically organized. We further demonstrate that tufted cells forming the IAS use the neuropeptide CCK as a transmitter. In addition, we show that the postsynaptic targets of the CCKergic IAS are the dendrites of GABAergic granule cells coursing through the IPL toward the EPL. As CCK is generally an excitatory neuropeptide, we suggest that the IAS functions to excite topographically discrete populations of granule cells. This action may lead to inhibition of equally discrete populations of mitral/tufted cells. Thus, the IAS may be an intrabulbar inhibitory circuit that coordinates topographically organized neural networks in the olfactory bulb. © 1994 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903460407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe fiber arrangement of the retinogeniculate pathway was investigated in the chiasm of Japanese monkeys (Macaca fuscata) by an iontophoretic injection of wheat germ agglutinin conjugated to horseradish peroxidase into the lateral geniculate nucleus (LGN). It has been claimed that there is a distinct retinotopy in the monkey chiasm, despite lack of any clear anatomical evidence. However, the present data indicate a rather gross retinotopy or almost no discernible retinotopy. Fibers from the foveal‐to‐peripheral axis of the temporal retina show substantially no retinotopy owing to a marked overlap of fibers in the anterolateral and the posterocentral parts of the ipsilateral hemichiasm. In contrast, the foveal‐to‐peripheral axis of the nasal retina is re‐formed in a gross dorsoventral order in the chiasm. That is, nasal foveal‐parafoveal fibers which arise from small cells (which are Pβ mode) pass in the dorsal part of the chiasm adjacent to the brain. They widely overlap nasal perifoveal fibers which cross the chiasm more ventrally with very little contact with the brain. The nasal perifoveal fibers also widely overlap nasal peripheral fibers which cross the chiasm more ventrally. Furthermore, the nasal peripheral fibers overlap nasal far peripheral fibers which arise from large cells (including many of the Pα mode) which run near the pial surface. Fibers from the dorsal and ventral nasal retina cross the midline of the posterior and anterior parts of the chiasm, respectively, and are finally positioned in the medioventral and ventrocentral parts in the tract. Consequently, the dorsoventral retinal axis is re‐formed posteroanteriorly in the midline of the chiasm and in a roughly mediolateral direction in the tract. Furthermore, the present study shows that the nasal and temporal retinal fibers coming from the same eye are acutely segregated in the prechiasmal region and the anterior part of the hemichiasm. © 1994

ISSN:0092-7317    

DOI:10.1002/cne.903460408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractTo investigate the developmental processes that generate the crustacean nervous system, we used a monoclonal antibody that recognises an antigen that is expressed in the developing embryonic nervous system of the lobster,Homarus gammarus.Expression of this antigen commences early in embryogenesis, occurs in all parts of the embryonic central and peripheral nervous systems, and continues into adulthood. Initial expression in the central nervous system correlates with the onset of neuronal process outgrowth. Light microscopic analysis shows that the antigen is found surrounding the cell bodies and processes of all neurons. Biochemical analysis indicates that the antigen, is a glycoprotein with an apparent molecular weight of 60 kD. Due to the early embryonic onset of its expression, this antigen is a useful cellular label for visualisation of‐ pattern formation in the developing nervous system; this is documented in detail for the developing stomatogastric nervous system. The fact that the 60‐kD antigen is expressed early in embryogenesis throughout the nervous system suggests that it might play an important role in the development of the lobster nervous system. © 1994 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903460409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractStudies of the projection from the vertebrate retina have contributed significantly to current concepts of neural development. The zebrafish has recently become a favored system for the study of development in general and neural development in particular. Although the development of both the optic nerve and the retinotectal projection of the zebrafish has been described, the retinofugal projection in its entirety has not. This paper describes it and also addresses the issue of projectional exuberance: i. e., transient projections to targets that are not innervated in the adult.The retinofugal projection of embryonic and larval zebrafish (32 hours to 7 days post‐fertilization) was labeled by intraocular injection of DiI (1,1′‐dioctadecyl‐3,3,3′,3′, tetramethylindocarbocyanine perchlorate) and then studied in wholemounts and sections.The first optic axons crossed the chiasm at 32 hours post‐fertilization and projected in a straight line to reach the tectum at about 44 hours. At 48 hours, a few optic axons deviated along either the tract of the posterior commissure or the tract of the postoptic commissure. By 72 hours (about the time of hatching) optic axons arborized in ten distinct regions, termed arborization fields. At 6–7 days post‐fertilization, the same ten arborization fields (nine contralateral, one bilater) were evident. Most of the arborization fields were located in the superficial neuropil and were not associated with morphologically identifiable clusters of somata. On the basis of various landmarks, the ten arborization fields are identified as precursors of retinorecipient nuclei previously described in other adult cypriniform fishes.The development was characterized by the nearly complete absence of any transient projections. Thus, the idea that axonal outgrowth is initially exuberant and trimmed back later is not supported by these results. © 19

ISSN:0092-7317    

DOI:10.1002/cne.903460410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractIsolatedNecturustaste receptor cells were studied by giga‐seal whole‐cell recording and electron microscopy to correlate electrophysiological properties with taste cell structural features. Dark (type I) cells were identified by the presence of dense granular packets in the supranuclear and apical regions of the cytoplasm. In response to a series of depolarizing voltage commands from a holding potential of −80 mV, these cells exhibited a transient, TTX‐sensitive inward Na+current, a sustained outward K+current, and a slowly inactivating inward Ca++current. Light (type II) cells were identified by a lack of granular packets and by an abundance of smooth endoplasmic reticulum distributed throughout the cell. In addition, isolated light cells had clear vesicular inclusions in the cytoplasm and blebs on the plasma membrane. Light cells were divided into two functional populations based upon electrophysiological criteria: cells with inward and outward currents, and cells with outward currents only. Light cells with inward and outward currents had voltage‐activated Na+, K+, and Ca++currents with properties similar to those of dark cells. In contrast, the second group of light cells had only voltageactivated outward K+currents in response to depolarizing voltage commands. These data suggest that dark cells and light cells with inward and outward currents are capable of generating action potentials and releasing neurotransmitters onto gustatory afferent neurons in response to taste stimulation. In contrast, light cells with outward currents only likely serve a different function in the taste bud. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903460411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY