摘要:

AbstractAlthough there is considerable evidence that primary afferent‐derived substance P contributes to the transmission of nociceptive messages at the spinal cord level, the population of neurons that expresses the substance P receptor, and thus are likely to respond to substance P, has not been completely characterized. To address this question, we used an antibody directed against the C‐terminal portion of the rat substance P receptor to examine the cellular distribution of the receptor in spinal cord neurons. In a previous study, we reported that the substance P receptor decorates almost the entire dendritic and somatic surface of a subpopulation of spinal cord neurons. In the present study we have taken advantage of this labeling pattern to identify morphologically distinct subpopulations of substance P receptorimmunoreactive neurons throughout the rostral‐caudal extent of the spinal cord. We observed a dense population of fusiform substance P receptor‐immunoreactive neurons in lamina I at all segmental levels. Despite having the highest concentration of substance P terminals, the substantia gelatinosa (lamina II) contained almost no substance P receptor‐immunoreactive neurons. Several distinct populations of substance P receptor‐immunoreactive neurons were located in laminae III‐V; many of these had a large, dorsally directed dendritic arbor that traversed the substantia gelatinosa to reach the marginal layer. Extensive labeling was also found in neurons of the intermediolateral cell column. In the ventral horn, we found that labeling was associated with clusters of motoneurons, notably those in Onuf's nucleus in the sacral spinal cord. Finally, we found no evidence that primary afferent fibers express the substance P receptor. These results indicate that relatively few, but morphologically distinct, subclasses of spinal cord neurons express the substance P receptor. The majority, but not all, of these neurons are located in regions that contain neurons that respond to noxious stimulation. © 1995 W

ISSN:0092-7317    

DOI:10.1002/cne.903560302

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractExtensive recent research has focused on the potential role of nitric oxide (NO) in synaptic plasticity. Could the capacity to synthesize NO be associated with neural and behavioral plasticity in the song system? The timing of song learning and of major developmental changes in song system anatomy are known. We searched for an association between NO and these developmental events by observing the distribution of neurons staining for NADPH‐diaphorase, an enzyme used in the synthesis of NO, in the brains of zebra finches. Both male and female brains were taken at different developmental ages from day 21 to adulthood. We found that the incidence of stained neurons in the song system nuclei is lower than in surrounding areas. The incidence of staining decreases with development, with most of the decrease occurring prior to the auditory learning phase of song learning. The developmental changes were quantified for area X and found to be highly significant, with a 56% decrease in staining frequency from day 21 to adulthood in males and a 23% decrease in females for the equivalent region. We also found a sexual dimorphism in the song system of adult birds, consisting of a reduced incidence of stained neurons in song system nuclei area X, high vocal center (HVC), and nucleus robustus (RA) archistrialis in males compared with females. These findings suggest that NO is less involved in the plasticity underlying song acquisition than in the earlier formation of the song system. © 1995 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903560303

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe neuropil of the stomatogastric ganglion of the crabCancer borealiscontains many neuronal processes that may be arranged either at random or in some form of orderly structure. In this study, we provide evidence for two types of order in the neuropil, a segregation of the processes based on their size and a cell‐specific distribution to the fine neurites. Identified neurons were injected with Lucifer yellow, fixed, and imaged as whole mounts with a confocal microscope. Four cell types were analyzed using the serial images, two pyloric neurons, one mixed pyloric/gastric neuron, and one gastric neuron. All of the neurons consisted of a ∼ 60‐μm‐diameter soma, a ∼ 20‐μm‐diameter primary neurite projecting into the center of the neuropil, a number of<10‐μm‐diameter medium‐sized neurites radiating away from the center, and many<3‐μm‐diameter fine neurites around the periphery of the neuropil. The neuropil can, therefore, be divided into three layers, a central core containing the largest neurites, an intermediate region containing both medium‐sized and fine neurites, and a peripheral neuropil containing mostly fine neurites. The distribution of the fine neurites was mapped using a three‐dimensional grid. We found that the fine neurites were distributed not at random within the neuropil but in consistent, cell‐specific

ISSN:0092-7317    

DOI:10.1002/cne.903560304

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractMice have been used for extensive studies on optic nerves and retinal ganglion cells, but mouse retinal ganglion cells have not been classified morphologically. In the present study, normally placed retinal ganglion cells and displaced retinal ganglion cells in pigmented and albino mice were classified morphologically using horseradish peroxidase. These cells were classified into three types according to the sizes of the soma and the dendritic field: type I cells, large soma and large dendritic field; type II cells, small‐to‐medium soma and small dendritic field; and type III cells, small‐to‐medium soma and large dendritic field. Some ganglion cells had both symmetric and asymmetric cells. Each type was further subdivided according to the termination level of dendrites in the inner plexiform layer and the dendritic branching pattern. Except for type III displaced ganglion cells, dendrites of the normally placed ganglion cells and the displaced ganglion cells ramify in the outer two‐fifths of the inner plexiform layer (sublamina a) or the inner three‐fifths of the inner plexiform layer (sublamina b). Type III displaced ganglion cells ramify only in sublamina a. Dendrites of some normally placed type I ganglion cells ramify in both sublaminae. Displaced biplexiform cells were observed, the dendrites of which ramify in both the inner and the outer plexiform layers. All cell types were found in both mouse strains. © 1995 Wil

ISSN:0092-7317    

DOI:10.1002/cne.903560305

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA family of tyrosine receptor kinases known collectively astrkreceptors plays an essential role in signal transduction mediated by nerve growth factor and related neurotrophins. To localize the majortrkreceptors (trkA, B and C) in the developing and adult central (CNS) and peripheral (PNS) nervous system, we generated monoclonal antibodies (MAbs) to extracellular (MAbs E7, E13, E16, E21, E29) and intracellular (MAb I2) domains of humantrkA fused to glutathione S‐transferase. Several MAbs (E7, E13, E16) recognized glycosylatedtrkA (gp 140trkand gp110trk) in Western blots, one MAb (E7) recognized non‐glycosylated (p80trk) and glycosylatedtrkA in immunoprecipitation assays, and two MAbs (E13, E29) detectedtrkA on the cell surface of NIH3T3 cells transfected with atrkA cDNA. Although generated totrkA fusion proteins, this panel of MAbs also recognizedtrkB andtrkC in flow cytometric studies of NIH3T3 cells transfected withtrkB ortrkC cDNAs. Thus, we used these pan‐trkMAbs to probe selected regions of the CNS and PNS including the hippocampus, nucleus basalis of Meynert, cerebellum, spinal cord, and dorsal root ganglion (DRG) to localizetrkA, B, and C receptors in the developing and adult human nervous system. These studies showed thattrkreceptors are expressed primarily by neurons and are detectable very early in the developing hippocampus, cerebellum, spinal cord, and DRG. Although the distribution and intensity oftrkimmunoreactivity changed with the progressive maturation of the CNS and PNS, immunoreactivetrkreceptors were detected in neurons of the adult human hippocampus, nucleus basalis of Meynert, cerebellum, spinal cord, and DRG. This first study oftrkreceptor proteins in the developing and adult human CNS and PNS documents the expression of these receptors in subsets of neurons throughout the developing and adult nervous system. Thus, although the expression oftrkreceptor proteins is developmentally regulated, the constitutive expression of these neurotrophin receptors by neurons in many regions of the adult human CNS and PNS implies that maturetrkreceptor‐bearing neurons retain the ability to respond to neurotrophins long after terminal neuronal differentiation is complete. © 1995 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903560306

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe purpose of the study was to determine if zebrin compartmentation developed in permanently isolated cerebellar cultures, in the presence of agents that block neuronal activity and in the absence of myelination and astrocytic ensheathment of Purkinje cells. Parasagittally oriented organotypic cultures derived from newborn mice and carefully undercut at explantation to exclude extracerebellar afferents were subjected to three conditions: (1) Some were maintained in standard nutrient medium; (2) some were chronically exposed to tetrodotoxin and elevated levels of magnesium to block neuronal activity; and (3) some were exposed to cytosine arabinoside for the first 5 days in vitro (DIV) to destroy granule cells and oligodendrocytes and functionally compromise astrocytes, so that the astrocytic survivors did not ensheath Purkinje cells. Cultures fixed as whole‐mount preparations were reacted with antibody to zebrin II. Cultures that were cryostat sectioned were dually reacted with antibody to zebrin II and calbindin. Groups of zebrin+and zebrin−Purkinje cells were evident after 14 DIV in all of the experimental conditions, indicating that zebrin compartmentation developed (1) in isolated cerebellar explants, (2) in the absence of neuronal activity, and (3) in the absence of neuron‐glia interactions such as myelination and glial ensheathment of Purkinje cell somata and dendrites. These results are consistent with the concept that expression of the zebrin+and zebrin−phenotypes is an intrinsic property of Purkinje cells. The fact that zebrin expression seems to depend on an intrinsic program of differentiation in Purkinje cells suggests some role for zebrin compartmentation in cerebellar function. © 1995 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903560307

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractPrevious studies have found opioid peptide‐like immunoreactivity in avian vocal control regions, but whether these regions contain receptors for opioid peptides has not been examined. To address this question, we used quantitative in vitro autoradiography to determine the anatomical distribution and to measure the densities of μ, δ, and κ opioid receptors in vocal control regions (area X higher vocal center, and nucleus intercollicularis) of adult male dark‐eyed juncos (Junco hyemalis). To evaluate whether opioid receptor densities in these regions depend on the activity of the reproductive system, we also measured these densities in birds collected during the spring, summer, and fall. We found area X, the higher vocal center, and nucleus intercollicularis to contain the three receptor types under study, but opioid receptor densities did not vary seasonally in any of these regions. The presence of specific opioid receptors in avian vocal control regions suggests the participation of opioids in the control of vocal behavior. This participation may consist of short‐term (e. g., auditory processing) and/or long‐term (e. g., neuronal plasticity) influences. © 1995 Wile

ISSN:0092-7317    

DOI:10.1002/cne.903560308

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractPeripheral regulation of cardiovascular function is fundamentally influenced by central excitation and inhibition of sympathetic preganglionic neurons in thoracic spinal cord. This electron microscopy study investigated whether the γ‐aminobutyric acid (GABA)‐ergic and glycinergic inhibitory innervation of sympathetic preganglionic neurons arises from mutually exclusive afferent populations. Sympathetic preganglionic neurons were retrogradely labeled with cholera β subunit. GABAergic terminals were identified using strict quantitative statistical analyses as those boutons containing significantly elevated levels of GABA‐like immunogold labeling (GABA+). Glycinergic terminals were classified as those boutons opposite postsynaptic gephyrin immunostaining containing background levels of GABA‐like immunogold labeling (gephyrin+/GABA−association). Approximately 43% of the synaptic terminals that contacted sympathetic preganglionic somata and proximal dendrites and that were opposite gephyrin were GABA−; the remaining 57% were GABA+. Only two GABA+boutons (4%) that synapsed on identified sympathetic preganglionic neuron (SPN) processes were not opposite gephyrin immunostaining (GABA+/gephyrin‐ association). GABA−/gephyrin+associations were anticipated given prior anatomical, physiological, and pharmacological data. The observed nearly one‐to‐one correspondence between postsynaptic gephyrin immunoreactivity and GABA+boutons was unexpected. Prior physiological and pharmacological experiments suggest that the postsynaptic effects of GABAergic inputs to sympathetic preganglionic neurons are mediated by activation of GABAAreceptors. Those data, the present results, and other molecular, biochemical, and anatomical studies of gephyrin in the central nervous system (CNS) are consistent with two hypotheses: (1) Postsynaptic gephyrin is associated with GABAAreceptors in the membranes of sympathetic preganglionic neurons, and (2) GABA+/gephyrin+associations do not necessarily predict colocalization of GABA and glycine within single boutons synapsing on sympathetic preganglionic somata and dendrites.

ISSN:0092-7317    

DOI:10.1002/cne.903560309

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe growth‐associated protein B‐50/GAP‐43 is thought to play a crucial role in axonal growth. We investigated, by quantitative immunoelectron microscopy, whether there are differences in the subcellular distribution of B‐50 in unmyelinated and myelinated axons of intact and regenerating sciatic nerves. Adult rats received an unilateral sciatic nerve crush and were euthanized 8 days later. Nerve pieces proximal from the crush site were embedded, and B‐50 was visualized by specific B‐50 antibodies and immunogold detection in ultrathin sections.The density of B‐50 at the plasma membrane of unmyelinated axon shafts was significantly increased in the ipsilateral regenerating nerve in comparison to that of the contralateral intact nerve. In contrast, there was no significant difference in the B‐50 density at the axolemma of myelinated regenerating and intact axon shafts.In the contralateral intact nerve, more B‐50 was associated with the axolemma of unmyelinated axons than with the plasma membrane of myelinated axons. The density of axoplasmic B‐50 was similar in intact unmyelinated and myelinated axon shafts, but was higher in regenerating nerve than in intact nerve. This suggests that enhanced axonal transport of B‐50 occurs during axon outgrowth.Our study demonstrates a differential subcellular distribution of B‐50 in unmyelinated and myelinated axon shafts in both the intact and regenerating sciatic nerve, indicating a differential inducible capacity for remodeling of the axon shafts.

ISSN:0092-7317    

DOI:10.1002/cne.903560310

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractCentral expression of the protooncogene c‐foswas used to examine areas receiving noxious sensory input from the rat temporomandibular joint (TMJ). Fos‐like immunoreactivity (Fos‐LI) in the caudal brainstem was visualized 2 hours after unilateral injection of the small‐fiber‐specific excitant /inflammatory irritant mustard oil into the TMJ region. Control animals received injection of either mustard oil into the subcutaneous fascia overlying the masseter muscle or mineral oil vehicle into the TMJ region. In all groups, Fos‐LI was consistently observed ipsilaterally in the spinal trigeminal nucleus and cervical dorsal horn and, bilaterally, in the nucleus of the solitary tract and. the ventrolateral medulla. The expression of Fos‐LI ipsilaterally in the paratrigeminal nucleus was variable. Within the trigeminal sensory complex, Fos‐LI was restricted to subnucleus caudalis and the caudal portions of subnucleus interpolaris near the level of the obex. Approximately 12% of Fos‐LI cells in subnucleus caudalis and in the cervical dorsal horn were found in laminae III‐VI. Compared to TMJ mustard oil injection, mineral oil injection produced less Fos‐LI at all rostrocaudal levels, whereas subcutaneous mustard oil injection produced less Fos‐LI in caudal subnucleus caudalis but similar amounts in the cervical dorsal horn. Neither of these injections yielded significant ipsilateral responses in subnucleus caudalis, indicating that Fos‐LI in this region following TMJ mustard oil injection could be ascribed solely to small‐fiber stimulation in the deep TMJ region. The wide rostrocaudal distribution of Fos‐LI within the caudal brainstem reflects the distribution of TMJ‐responsive nociceptive neurons that may underlie the spread and referral of pain from the TMJ

ISSN:0092-7317    

DOI:10.1002/cne.903560311

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY