ISSN:0092-7317    

DOI:10.1002/cne.903330202

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

年代:1993

数据来源: WILEY

摘要:

AbstractWe investigated the ultrastructural localization, afferent sources, and arterial pressure effects of corticotropin‐releasing factor (CRF) in the nucleus reticularis rostroventrolateralis (RVL), a region of the ventrolateral medulla containing C1 adrenergic neurons and sympatho‐excitatory reticulospinal afferents to sympathetic preganglionic neurons. A polyclonal antibody, to CRF was localized in acrolein‐fixed sections through the rat RVL by the peroxidase–antiperoxidase (PAP) method. Light microscopy showed that 1–7 perikarya/30 μm section and numerous varicose processes contained CRF‐like immunoreactivity (CRF‐LI). By electron microscopy, CRF‐LI was most intensely localized to large (80–100 nm) dense‐core vesicles within numerous terminals and a few perikarya and large dendrites. Approximately half of the terminals containing CRF‐LI were in direct contact with unlabeled perikarya or dendrites; the remainder were in apposition to either unlabeled terminals or astrocytes. Most synaptic specializations were asymmetric synapses on small, unlabeled dendrites.To examine potential extrinsic sources of CRF‐containing terminals in the C1 area of the RVL, PAP immunocytochemical localization of CRF was combined with retrograde transport of wheat germ agglutinin‐conjugated horseradish peroxidase (WGA‐HRP). In all cases examined, a number of dually labeled neurons were found in the paraventricular nucleus (PVN) of the hypothalamus and a few dually labeled neurons were observed in the nuclei of the solitary tract; these labeled neurons were ipsilateral to the unilateral injection of WGA‐HRP into the C1 area. Fewer dually labeled perikarya were detected in the lateral hypothalamic area and the lateral parabrachial nuclei, ipsilateral to the WGA‐HRP injection.Additional physiological studies showed that bilateral microinjections of CRF into the C1 area of the RVL of urethane‐anesthetized rats elicited a dose‐related increase in arterial pressure. The results suggest that within the C1 area of the RVL, CRF released from terminals, arising predominantly from the PVN of the hypothalamus and probably from local neurons as well, may excite sympathoexcitatory reticulosp

ISSN:0092-7317    

DOI:10.1002/cne.903330203

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

年代:1993

数据来源: WILEY

摘要:

AbstractNervous is an autosomal recessive mutation in mice (gene symbol,nr) that produces a progressive cerebellar and retinal degeneration. We have examined various cytopathological features of the photoreceptor degeneration by light microscopy. An increase in the number of pyknotic photoreceptor nuclei in the outer nuclear layer (ONL) is first seen at postnatal day (P) 11. Between P13 and P19 there is a rapid loss of photoreceptors, with the ONL about 60% the thickness of littermate controls at P19. Between P19 and 2.5 months of age, photoreceptor cell loss is minimal, and there is a relatively slow loss of these cells between 3 and 7.5 months of age. At 7.5 months, the ONL consists of single row of nuclei, most of which are lost over the ensuing months, although a few photoreceptor nuclei persist at 17 months of age and older. Both rods and cones are lost at comparable rates for the first 2 months of life, but rods are somewhat preferentially lost at later ages. A very slight central‐to‐peripheral gradient of photoreceptor degeneration exists in thenr/nrretina, but no superior‐inferior hemispheric differences are evident. The rate, spatiotemporal gradient, and hemispheric similarity in photoreceptor degeneration are the same in albinonr/nrmice reared either in cyclic light or in the dark, and in pigmentednr/nrmice. Autoradiographic analysis of rod outer segment renewal shows that outer segment membranes are synthesized in nervous homozygotes. Rhythmic outer segment disc shedding and phagocytosis by the retinal pigment epithelium occur at approximately normal rates innr/nrmice.Histochemical and immunocytochemical study of the interphotoreceptor matrix (IPM) reveals the exclusion of stainable IPM from the outer segment zone by lamellar whorls of outer segment membrane, accumulation of stainable IPM in the basal region of the outer segment zone, and the absence of an intense band of stainable IPM at the apical surface of the retinal pigment epithelium. These changes in the IPM are similar to those seen in the Royal College of Surgeons rat. However, comparison of cytopathological changes in these two mutants reveals that the IPM defect probably is not the primary cause of photoreceptor cell death innr/nrmice, and that similar phenotypic appearance does not necessarily signify similar pathological processes. © 1993 Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903330204

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

年代:1993

数据来源: WILEY

摘要:

AbstractNervous mutant mice (nr/nr) show a rapid loss of most of cerebellar Purkinje cells between the ages of 3 and 7 weeks, as well as a progressive photoreceptor cell degeneration that occurs most rapidly between postnatal days (P) 13 and 19, but with a much slower attrition during the subsequent months. We have carried out an electron microscopic analysis ofnr/nrand littermate control mice at representative ages to characterize the subcellular cytopathological changes in this form of retinal degeneration, to gain insight into photoreceptor cell degeneration mechanisms by comparing these changes to those in other rodent forms of retinal degeneration, and to compare the photoreceptor changes with those of cerebellar Purkinje cells.Ultrastructural observations were limited to rod photoreceptors, since the number of cones was limited in our micrographs. The retinas ofnr/nrmutant mice can be distinguished from those of normal littermates as early as postnatal day (P) 6. At this time, some of the mitochondria in rod inner segments are larger and more rounded than normal. This represents the earliest cytopathological change thus far observed in this mutant. As early as P9 and thereafter, the volume and integrity of rod outer segment membranes are reduced from normal. In the inner segments of some rod photoreceptor cells, there is a reduction in the volume or number of polyribosomes as early as P11, a reduction in rough endoplasmic reticulum as early as P13, and reduced incidence and less organized Golgi membranes as early as P16. Qualitative evaluation and quantitative stereological analysis show that the enlarged mitochondria in rod inner segments never become normal in shape or size. No changes are seen in the inner retinal layers at any age. Despite similarities with inherited retinal dystrophy in the Royal College of Surgeons rat, as noted in the original description of retinal degeneration innr/nrmice, ultrastructural features clearly distinguish these mutants. Moreover,nr/nrmice can be distinguished from all other murine forms of retinal degeneration by electron microscopy. © 1993 Wiley‐Liss, I

ISSN:0092-7317    

DOI:10.1002/cne.903330205

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe present double‐labeling study was designed to demonstrate the morphological framework for motor control in coordinated distal and proximal forelimb movements, which may partly, at least, depend on corticocortical and thalamocortical inputs to the forelimb area in the primary motor cortex. After intracortical microstimulation mapping of the forelimb area in the primary motor cortex of four macaque monkeys, a retrograde tracing study with fluorescent dyes was attempted to label simultaneously neurons in cortical and subcortical sites projecting to the distal forelimb representation area and those projecting to the proximal representation area of the primary motor cortex. Neurons projecting to distal and proximal forelimb parts of the primary motor cortex were largely separate in the following areas: the premotor area, primary somatosensory area, secondary somatosensory area, area 5, and thalamus. In contrast, there was no precise topographic organization of labeled projection neurons in the following areas: the supplementary motor area, cingulate motor area, primary motor cortex adjacent to the injection sites, claustrum, and basal nucleus of Meynert. The present study revealed that the forelimb area of the primary motor cortex receives both segregated and intermixed inputs from cortical and subcortical sources. In particular, the fact that the forelimb area of the primary motor cortex receives topographically organized inputs from the premotor area and nontopographically organized inputs from the supplementary motor area and cingulate motor area indicates possible different functional roles of frontal premotor areas in control of coordinated distal and proximal forelimb movements. © 1993 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903330206

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe projection from the rat's superior colliculus (SC) to the lateral posterior nucleus of the thalamus (LP) has previously been described as arising from a morphologically homogeneous population of neurons in thestratum opticum(SO). The present study combined immunocytochemistry with retrograde tracing and lesion techniques to determine whether or not the SC → LP projection arose from neurons that were also neurochemically homogeneous. The combination of retrograde tracing and immunocytochemistry with an antibody directed against calbindin‐D 28K (CBD) showed that 64.4% of the neurons that project from SC to LP contain this calcium‐binding protein. Retrograde tracing and immunocytochemistry for adenosine deaminase (ADA) showed that a smaller number of tecto‐LP cells (15.7%) were immunoreactive (IR) for this enzyme. Moreover, nearly all (93.0%) of the ADA‐IR tecto‐LP cells also contained CBD‐IR. Adenosine deaminase‐IR axons in LP were restricted to the dorsomedial portion of the nucleus and their density was substantially reduced after ablation of the ipsilateral superficial SC laminae. The lateral posterior nucleus contained numerous CBD‐IR cells and fibers throughout its extent and it was thus difficult to determine the extent to which the extra‐perikaryal CBD‐IR in this nucleus was dependent upon the tecto‐LP pathway. Nevertheless, destruction of the ipsilateral SC did reduce the density of CBD‐IR in LP. These results suggest that the SC → LP projection in rat arises from at least four neurochemically distinct cell groups: (1) those that contain CBD, (2) those that contain both CBD and ADA, (3) a very small population that contains only ADA, and (4) a group that is not recognized by either of these markers. Our results further suggest that ADA containing fibers may have a more restricted terminal distribution in LP than axons that contain only

ISSN:0092-7317    

DOI:10.1002/cne.903330207

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

年代:1993

数据来源: WILEY

摘要:

AbstractWe have used the evoked expression of both immediate early gene (IEG)‐encoded proteins (Krox‐24, c‐Fos, Fos B, Jun D, Jun B, c‐Jun), and dynorphin to monitor sensory processing in the spinal cords of rats undergoing subacute or chronic somatic inflammation (i.e., subcutaneous inflammation of the plantar foot and monoarthritis, respectively). Behavioral and immunocytochemical approaches were conducted in parallel up to 15 weeks postinjection in order to detect possible relationships between clinical evolution and spatiotemporal pattern of IEG‐encoded protein expression.Each disease had specific characteristics both in terms of their clinical evolution and pattern of evoked protein expression. All IEG proteins were expressed in both cases. Most of the staining was observed in both the superficial layers of the dorsal horn and deep dorsal horn (laminae V–VII and X). Monoarthritis was distinguished by a high level of total protein expression. Staining was especially dense in the deep dorsal horn. More labelled cells were observed at 1–2 days and at 2 weeks postinjection, corresponding to the initiation and progressive phases of the disease, respectively. Subcutaneous inflammation was characterized by a moderate level of total IEG expression. More labelled cells were observed in the first day following injection. It is the relative degree of expression of each IEG‐encoded protein with regard to the others that characterized the progression of the diseases. Early stages of the diseases coincided with the expression of all Fos and Jun proteins, while late stages showed an increase in Jun D and Fos B involvement; Krox‐24 was induced mostly during the early phases and/or periods of paroxysm of the diseases. Persistent stimulation was characterized by a predominant expression in deep versus superficial layers of the dorsal horn. Evoked expression of c‐Jun in motoneurons was only observed in monoarthritis. The peak of dynorphin expression was late in regard to both the induction of inflammation and period of maximal IEG‐encoded protein expression.The present work indicates that the neural processing that takes place during progression of these diseases can be monitored well at the spinal cord level by using the expression of an array of IEG‐encoded proteins. Study of long term evolutive diseases and especially those that evolve into chronicity can largely benefit from such an approach.

ISSN:0092-7317    

DOI:10.1002/cne.903330208

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe present study in the male Djungarian hamster determined the neuroanatomical distribution and morphology of gonadotropin‐releasing hormone (GnRH) neurons which innervate the medial basal hypothalamus during sexual maturation. Prepubertal, peripubertal, and postpubertal males were perfused, brains were removed, and crystals of the fluorescent tract tracer, DiI, were implanted directly into the median eminence of the brain. Eight weeks later, brains were sectioned and processed for GnRH immunofluorescence. At all ages, GnRH cell bodies were bipolar or unipolar; both subtypes were labeled with DiI in proportion to their respective numbers in each brain region. GnRH perikarya were distributed in a diffuse ventromedial continuum from the septum through the anterior hypothalamus. In prepubertal males, DiI was present in the majority of GnRH neurons (54% of total) that were located in brain regions rostral to and including the medial preoptic area. In lateral and caudal brain areas, fewer GnRH perikarya contained DiI (28% of total or less). With sexual maturation, fewer GnRH somata were labeled with DiI in areas rostral to the hypothalamus. The data suggest that bipolar and unipolar GnRH neurons in the forebrain, rostral to the preoptic area, are major contributors to the GnRH innervation of the median eminence in the male Djungarian hamster. With the onset of puberty, the finding that decreasing numbers of GnRH perikarya directly project to the medial basal hypothalamus suggests that fewer GnRH neurons constitute the final common pathway that controls gonadotropin secretion. © 1993 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903330209

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

年代:1993

数据来源: WILEY

摘要:

AbstractSprouted collateral axons were observed in the electrosensory lateral line lobe (ELL) of gymnotiform teleosts (Apteronotus leptorhynchus:) following the ablation of the supraorbital branch of the anterior lateral line nerve. Ablation was accomplished by using microinjections of the toxic lectin ricin. Sprouted axons were followed for up to 26 weeks postablation. Ricin exposure severely reduced axonal numbers and the peripheral electroreceptors in the region innervated by these fibers. To visualize sprouted fibers, intact lateral line afferent nerve branches were anterogradely labelled with the neuronal tract tracers horseradish peroxidase or cobalt chloride, or the monoclonal antibody Q26A3.Within the four somatotopically organized ELL segments, sprouted collaterals were first observed two weeks after ricin injection in the medial and centromedial segments, and four weeks postinjection in the centrolateral and lateral segments. Sprouting involved intrasegmental, horizontally directed axons from adjacent nerve branch terminal fields, and mixed intra‐and extrasegmental, dorsally directed axons from the ELL deep fiber layer. The sprouting response was robust but variable in its timing, peaking between 6 and 12 weeks. Subsequently, the intrasegmental, horizontally directed fibers were retained but the mixed dorsally directed fibers, including all extrasegmental axons, were retracted. Therefore, this sprouting response appears to consist of a collateral overproduction followed by a selective axonal retraction. In our view, the most likely explanation for this axonal retraction is that the descending inputs from the isthmus and the cerebellum, as well as commissural fibers from the contralateral ELL, maintain established somatotopic relationships by eliminating somatotopically mismatched sprouted collaterals. © 1993 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903330210

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe morphological organization of the central projections of the cat cochlear spiral ganglion into the cochlear nucleus was previously investigated by creating restricted lesions in the anteroventral cochlear nucleus (AVCN) to ablate selectively either the lateral or the medial aspect of isofrequency projection laminae. Such lesions resulted in highly selective retrograde degeneration of spiral ganglion cells. Ablation of the lateral part of the AVCN caused degeneration of cells within the scala tympani part of the ganglion, whereas medial ablations within the AVCN induced degeneration of the scala vestibuli aspect of the ganglion. The peripheral axons also degenerated and this fiber loss exhibited selective topographies that paralleled the cell loss within the spiral ganglion, although this phenomenon was more prominent in the proximal part of the osseous spiral lamina near the ganglion and less obvious more distally near the habenula perforata.In this investigation, inner hair cells (IHCs) from these selective lesion cases were evaluated by electron microscopy of serial sections through the basal synaptic regions. Results demonstrated differential degeneration of afferent synapses, with greater (but not completely selective) loss of pillar synapses after lateral AVCN lesions and greater loss of modiolar synapses after medial lesions. Because auditory nerve fibers of different spontaneous discharge rates (SRs) have different spatial distributions on the IHC (Liberman, Science216:1239, 1982), our results suggest that this SR‐based organization is maintained in a topographic organization across the vertical (scala tympani‐to‐scala vestibuli) dimension of the spiral ganglion cell cluster and carried into the ventral cochlear nuclei (VCN). Thus, in addition to the spiral frequency organization represented by the dorsal‐to‐ventral frequency map in the VCN, there is also an orderly organization of inputs from high‐ and low‐SR fibers across the lateral‐to‐medial dimension of the VCN such that the lateral isofrequency laminae receive a proportionately greater input from high‐SR fibers, whereas medial isofrequency laminae receive preferential input from low‐ and medium‐SR fibers.

ISSN:0092-7317    

DOI:10.1002/cne.903330211

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

年代:1993

数据来源: WILEY