摘要:

AbstractTwo well‐stained, horseradish peroxidase‐filled varieties of putative ON‐OFF directionally selective ganglion cells, G14a and G15, that project to the dorsolateral optic tectum (Guiloff and Kolb [1992a] Vis. Neurosci. 8:295–313) were studied qualitatively and quantitatively. Both were bistratified ganglion cells with one tier of dendrites; in the OFF sublamina and the other in the ON sublamina of the inner plexiform layer (IPL). The cells were serially sectioned and examined for synaptic inputs by electron microscopy. Portions of the dendritic trees were also analyzed after postembedding immunocytochemistry for neurotransmitter candidates gamma aminobutyric acid (GABA), glycine, choline acetyltransferase (ChAT), and glutamate in presynaptic neurons.Both G14a and G15 are dominated by amacrine cell inputs and have only minor bipolar cell involvement. Probably at least two different types of bipolar cell are presynaptic. Both ganglion cells receive some GABA‐Positive (GABA+) amacrine inputs and G14a receives ChAT+amacrine inputs. Glycine+, and glutamate+inputs could not be detected in either cell. The GABA+inputs appeared to be regionally arranged in the dendritic trees. The general distribution of amacrine and bipolar inputs to the two tiers of dendrites in both cell types appeared to be asymmetrical, both along the radial extent of the dendritic trees and within the depth of the IPL.Our data support some aspects of the current models for directional selectivity. We suggest candidate bipolar and amacrine cells that could have input to these ganglion cells. Since many of the putative presynaptic amacrine cells coincide with directionally selective types recorded and stained, by other authors, we propose that in turtle retina directional selectivity arises in neurons presynaptic to the ganglion cells. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903470302

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractTo investigate the morphology, distribution, and connections of parvalbumin‐containing neurones in the caudate‐putamen of primates, perfuse‐fixed sections were stained to reveal parvalbumin immunoroactivity. In agreement with previous observations, the caudate‐putamen was rich in parvalbumin‐positive neurones and neuropil. The neuropil staining was uneven such that the dense background staining was interspersed with zones of relatively weak staining. The distribution corresponded to the striosome/matrix system as defined by substance P or met‐enkephalin immunostaining in adjacent sections. Because parvalbumin‐positive neurones are present in regions known to project to the caudate‐putamen and the majority of parvalbumin‐positive terminals in the matrix formed asymmetric synapses, it is concluded that the uneven staining is probably due to afferents of the neostriatum.The morphology of the parvalbumin‐immunoreactive neurones varied between the striosomes and matrix; those in the matrix were smaller and possessed dendritic arborisations that were relatively uniform, whereas those in the striosomes were generally more extensively stained and possessed a greater variation in their dendritic branching patterns. The dendrites frequently crossed the boundary between the striosomes and matrix. A population of giant parvalbumin‐immunoreactive neurones was also observed in the putamen. Electron microscopic analysis revealed that, in addition to terminals forming asymmetric synapses, a smaller population formed symmetric synaptic specialisations and are presumed to be derived from the local parvalbumin‐immunoreactive neurones. Terminals of the latter group formed synapses with medium‐sized spiny neurones. Because parvalbumin‐positive neurones receive input from the cortex, they may transmit cortical information to spiny neuro

ISSN:0092-7317    

DOI:10.1002/cne.903470303

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractDouble staining immunohistochemistry was used to investigate the origin and projection of nerves with substance P (SP) immunoreactivity (‐IR) in the walls of the major cerebral arteries in two microchiropteran species. In the greater horseshoe bat, most of the cerebral perivascular nerves with SP‐IR did not exhibit calcitonin gene‐related peptide (CGRP)‐IR, but emitted bright immunofluorescence for vasoactive intestinal polypeptide (VIP). In this species, a large number of cell bodies with both SP‐ and VIP‐IR were observed in many cranial ganglia along various branches of the facial and glossopharyngeal nerves. There were no cell bodies immunoreactive for either SP and VIP in the two sensory (trigeminal and upper cervical dorsal root), two sympathetic (superior cervical and stellate), or two vagal (superior and jugular) ganglia. In addition, several thick fiber bundles with both SP‐ and VIP‐IR were present in the wall of the cerebral carotid artery, and descended progressively reaching as far as the middle part of the basilar artery (BA). These and other findings suggest that SP‐immunoreactive nerves with VIP‐IR but not CGRP‐IR, which contribute to the rich innervation of the vertebrobasilar system in the greater horseshoe bat, originate from neurons with the same combination of peptide‐IR in the major or local facial or glossopharyngeal parasympathetic ganglia, and enter the cranial cavity along the internal carotid artery. In the bent‐winged bat, however, cerebral perivascular SP‐immunoreactive nerves, as well as SP‐immunoreactive neurons within the trigeminal and upper cervical dorsal root ganglia (uCDRG), showed neither CGRP‐IR nor VIP‐IR, and were mostly confined to the caudal BA and the vertebral artery (VA). These observations, in addition to the projection of this nerve type to the BA via the VA as fiber bundles, or through the meninges, indicate that the principal source of the cerebrovascular SP‐immunoreactive innervation in this species i

ISSN:0092-7317    

DOI:10.1002/cne.903470304

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe neuropeptide content of neurons of the nucleus of the solitary tract (NTS), which have local and commissural projections to the dorsal motor nucleus of the vagus (DMNX) and to NTS, were demonstrated in the pigeon (Columba livia) by using a combined fluorescein‐bead retrograde‐transport‐immunofluorescence technique. The specific peptides studied were bombesin, cholecystokinin, enkephalin, galanin, neuropeptide Y, neurotensin, and substance P. Perikarya immunoreactive for bombesin were located in the Medial tier subnuclei of NTS and the caudal NTS. Most galanin‐ and substance P‐immunoreactive cells were found in subnucleus medialis ventralis. Cells immunoreactive for neuropeptide Y were found in the medial tier of NTS and in the lateral tier, especially in subnucleus lateralis dorsalis intermedius. The majority of enkephalin‐ and neurotensin‐immunoreactive cells were found centrally in subnuclei medialis dorsalis and medialis intermedius. Cells immunoreactive for cholecystokinin were located in subnuclei laterolis dorsalis pars anterior, medialis superficialis, and the caudal NTS.Based on the presence of retrogradely labeled cells, numerous neurons of the medial tier of NTS, but extremely few lateral tier NTS neurons, had projections to the ipsilateral and contralateral DMNX and NTS. The number of retrogradely labeled NTS cells was always greater ipsilateral than contralaterally. The percentages of peptide‐immunoreactive NTS cells that projected to the ipsilateral and contralateral DMNX were in the ranges of 29–61% and 10–48%, respectively. The percentages of peptide‐immunoreactive NTS cells that projected to the contralateral NTS ranged from 13 to 60%. Peptide‐immunoreactive NTS cells that have local and commissural projections to DMNX and NTS may act as interneurons in vagovagal reflex pathways and in the integration of visceral sensory and forebrain input to NTS and DMNX.

ISSN:0092-7317    

DOI:10.1002/cne.903470305

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractIn the present studies we have evaluated the complexity and scaling properties of the morphology of retinal neurons using fractal dimension as a quantitative parameter. We examined a large number of cells fromPseudemys scriptaandMauremys caspicaturtles that had been labeled using Golgi‐impregnation techniques, intracellular injection of Lucifer Yellow followed by photooxidation, intracellular injection of rhodamine conjugated horseradish peroxidase, or intracellular injection of Lucifer Yellow or horseradish peroxidase alone. The fractal dimensions of two dimensional projections of the cells were calculated using a box counting method. Discriminant analysis revealed fractal dimension to be a significant classification parameter among several other parameters typically used for placing turtle retinal neurons in different cell classes. The fractal dimension of amacrine cells was significantly correlated with dendritic field diameters, while the fractal dimensions of ganglion cells did not vary with dendritic field span. There were no significant differences between the same cell types in two different turtle species, or between the same types of neurons in the same species after labeling with different techniques. The application of fractal dimension, as a quantitative measure of complexity and scaling properties and as a classification criterion of neuronal types, appears to be useful and may have wide applicability to other parts of the central nervous system. © 1994 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903470306

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThere is little doubt that trigeminal nociceptive neurons play a critical role in signaling the presence of harmful, or potentially harmful, orofacial stimuli. Unfortunately, there is only a limited understanding of how these neurons code such stimuli and whether this code is maintained in those structures responsible for generating overt reactions. The present series of experiments were designed to quantitatively document the response properties of nociceptive neurons in the rat trigeminal pars caudalis using the same electrical and innocuous and/or noxious mechanical and thermal stimuli employed in the characterization of nociceptive neurons with orofacial receptive fields in the rat superior colliculus. Neurons were classified as either low‐threshold mechanoreceptive, wide‐dynamic‐range, or nociceptive‐specific (type I, II) depending on their responsiveness to these stimuli. Nociceptive pars caudalis neurons (92/135, 68%) had receptive field organizations and input fibers (as indicated by latencies to electrical stimuli) quite different from those of low‐threshold neurons (43/135, 32%). Nociceptive stimulus‐response relationships for the population of wide‐dynamic‐range and nociceptive‐specific type I neurons to contact heat stimuli were positively accelerating power functions with exponents of 3.9 and 4.4, respectively. This contrasted sharply with the low‐threshold component of wide‐dynamic‐range neurons which was a negatively accelerating power function with an exponent of 0.7. All categories of nociceptive neuron also responded vigorously to cold stimuli. The thresholds of both hot and cold stimuli were often below psychophysical estimates of thermal pain, suggesting that “nociceptive” neurons process far more information than that required, to signal potentially harmful stimuli. The fundamental similarities in nociceptive properties in pars caudalis and other structures of the central nervous system suggest that there is little transformation of the information encoded at successive levels of the neuraxis. This is consistent with the idea that the functional role of nociceptive neurons is refiected more in which circuits they are integrated and less in differences in their physiological propert

ISSN:0092-7317    

DOI:10.1002/cne.903470307

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe allatostatins are a family of peptides isolated originally from the cockroach,Diploptera punctata. Related peptides have been identified inPeriplaneta Americanaand the blowfly,Calliphora vomitoria. These peptides have been shown to be potent inhibitors of juvenile hormone synthesis in these species. A peptide inhibitor of juvenile hormone biosynthesis has also been isolated from the moth,Manduca sexta; however, this peptide has no structural homology with theD. punctata‐type allatostatins. Investigations of the phylogeny of theD. punctataallatostatin peptide family have been started by examining a number of nonarthropod invertebrates for the presence of allatostatin‐like molecules using immunocytochemistry with antisera directed against the conserved C‐terminal region of this family. Allatostatin‐like immunoreactivity (ALIR) was demonstrated in the nervous systems ofHydra oligactis(Hydrozoa),Moniezia expansa(Cestoda),Schistosoma mansoni(Trematoda),Artioposthia triangulate(Turbellaria),Ascaris suum(Nematoda),Lumbricus terrestris(Ohgochaeta),Limax pseudoflavus(Gastropoda), andEledone cirrhosa(Cephalopoda). ALIR could not be demonstrated inCiona intestinalis(Ascidiacea). These results suggest that molecules related to the allatostatins may play an important role in nervous system function in many invertebrates as well as in insects and that they also have an ancient evolutionary lineage. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903470308

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe existence of direct synaptic input from the neocortex to intermediate zone and white matter interstitial neurons was examined in both neonate and adult cats. This projection was studied by injecting the anterograde tracerPhaseolus vulgarisleucoagglutinin (PHA‐L) into the neocortex and examining whether cortical efferent axons formed synapses in the intermediate zone or white matter. Anterogradely labeled boutons establishing synapses in the intermediate zone and white matter were found at the electron microscopic level after injecting PHA‐L into the primary visual, somatosensory, and suprasylvian cortex. Although labeled synapses were found in the intermediate zone of kittens injected at postnatal days 2 and 6, their morphological features appeared immature compared to those found in kittens aged 3 weeks or in adults. Postsynaptic targets of efferent cortical axons were studied in serial sections and shown to be dendritic shafts and spines.This paper shows that cortical efferent axons contribute synapses to interstitial neurons located in the intermediate zone of kittens and white matter of adults. The functional role of the corticointermediate zone/white matter projection remains to be determined. © 1994 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903470309

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe decapeptide gonadotropin‐releasing hormone (GnRH) is a key hormone for the central regulation of reproduction. The distribution of salmon GnRH (sGnRH), which is the major form in salmonids, has been studied in different fish species by immunocytochemistry. Discrepancies in data concerning the distribution of sGnRH perikarya led us to investigate this problem in two species, the Atlantic salmon and the rainbow trout, with in situ hybridization of sGnRH messenger, a highly specific molecular tool. By Northern blot analysis, the rainbow trout sGnRH messenger appears to be about 500 bases in length, which is close to those isolated from Atlantic salmon or masu salmon and characterized previously, In situ hybridization with riboprobes generated with Atlantic salmon sGnRH cDNA demonstrated that sGnRH perikarya are restricted to the ventral part of olfactory bulbs, telencephalon, and preoptic area. They are distributed on a nearly continuous line extending from the olfactory bulbs to the preoptic area in both salmonid species studied.Despite the presence of GnRH‐like immunoreactivity in the preoptic magnocellular nucleus (NPOm) and in the tegmentum of the midbrain (MT), the sGnRH mRNA is not present in these two structures. Stained cells in NPOm could be target cells for GnRH and immunoreactive neurons in MT are likely to be chicken GnRH‐II containing cells. Our study not only gives a precise distribution of the sGnRH system in two salmonids, Atlantic salmon and rainbow trout, but also clarifies the ambiguous data published up to now in rainbow trout. © 1994 Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903470310

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractVGF is a neuronal polypeptide first identified as a cDNA clone in a gene library from nerve growth factor‐stimulated PC12 cells. In the present paper, the expression of VGF is examined for the first time throughout the adult rat central nervous system with immunocytochemistry and Northern blot analysis. VGF RNA was found in all brain regions studied, including hypothalamus, hippocampus, cerebellum, olfactory bulb, and cortex. In contrast to the relatively strong immunostaining of hypothalamic neurons, the level of VGF RNA expression in the hypothalamus was relatively low in comparison with other brain regions. With the aid of antisera raised against bacterially produced recombinant proteins containing parts of the VGF sequence, immunoreactive neurons were detected throughout the brain, including regions of the olfactory tubercle, caudate‐putamen, thalamus, cortex, amygdala, hypothalamus, mid brain, and hippocampus. VGF‐immunoreactive neurons did not contain detectable amounts of nerve growth factor receptor; other neurons that showed nerve growth factor receptor immunoreactivity expressed no VGF immunoreactivity. The lack of colocalization of VGF and nerve growth factor receptor suggests that, unlike expression in PC12 cells, VGF expression in neurons from the central nervous system does not require nerve growth factor stimulation. Within the hippocampus, the location of VGF‐immunoreactive cells was suggestive of inhibitory interneurons. ‐VGFimmunoreactive axons and terminals were found throughout the brain. These observations extend our earlier work on VGF expression in the hypothalamus to other regions of the brain and support the conclusion that although VGF expression is only detected in subsets of neurons in each brain region, these subsets are widely distributed throughout the central nervous system. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903470311

出版商:Wiley‐Liss, Inc.    

年代:1994

数据来源: WILEY