摘要:

AbstractImmunocytochemical studies using antibodies raised against a number of probable synaptic transmitters of the mesodiencephalic area, and fibre‐tracing studies using wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP), have been performed in adult cats. Glutamate and aspartate immunoreactivity produced a strong labelling of many cell bodies and terminals in the nucleus of Darkschewitsch (ND). γ‐Aminobutyrate (GABA) immunoreactivity in the ND appeared as a moderate label in some small neurones, and as a strong label in a few glial‐like cells, in addition to being present in high levels to produce strong labelling in many GABA‐immunopositive terminals that possessed pleomorphic vesicles. Some choline acetyltrans ferase‐positive terminals and dendrites and a few substance P‐positive fine fibres possessing varicosities also were observed in the ND.Following WGA‐HRP injection in the ND, dense terminal labelling was seen ipsilaterally in the rostral half of the medial accessory olive, suggesting that there may be a certain degree of mediolateral and dorsoventral topographic correspondance within the ND‐olive projection. In the same cases, many cell bodies containing HRP reaction product also were found (1) ipsilaterally in the motor cortex, anterior pretectal nucleus, and a restricted area of the caudal part of the substantia nigra pars reticulata; (2) contralaterally in the anterior and posterior interposed cerebellar nuclei as well as in a portion of the lateral cerebellar nucleu and (3) bilaterally in the zona incerta, the posterior pretectal nucleus, the pedunculopontine tegmental nuclei, the spinal trigeminal nucleus, the dorsal column nuclei, and the spinal cord. Details of the interrelationships and functional considerations amongst the ND, adjacent nuclei, and longitudinal zones of the cerebellum are discussed. ©

ISSN:0092-7317    

DOI:10.1002/cne.903610402

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractModified activity of the rat vibrissae from birth to adulthood induces profound alterations of the responsiveness and selectivity of neurons in the contralateral somatosensory barrel field cortex of adult rate. Because these functional properties are under the control of the intracortical inhibitory mechanisms, we investigated the effects of unilateral removal of face pad vibrissae on the quantitative distribution of intracortical γ‐aminobutyric acid (GABA)‐immunoreactive neurons in the rat contralateral and ipsilateral barrel field cortices. This distribution was then compared to a population of control animals.For the entire cortical depth, no significant changes in the density (7,700/mm3vs. 7,400/mm3), proportion (13.6% vs. 14.4%), or size (11.7 μm vs. 12.5 μm) of GABA‐immunoreactive neurons were found in the left contralateral vs. the right ipsilateral barrel field cortex. However, in cortical layer IV, contralateral to the deprivation, the density and proportion of GABA‐immunoreactive neurons were lower (6,300/mm3vs. 13,900/mm3, 6.0% vs. 13.6%;P<0.01), and these neurons were larger (mean projected height of 15.1 μm vs. 10.8 μm;P<0.01) than in the ipsilateral barrel field cortex, suggesting a specific loss of GABA expression in a subpopulation of small intracortical neurons.In addition to changes in the contralateral layer IV, GABA‐immunoreactive neurons located in the ipsilateral granular layer were also affected. Indeed, their numerical density (13,900/mm3) and proportion (13.6%) were higher (P<0.01) than in both hemispheres of control animals (average of 10,050/mm3and 9.4%). On the other hand, GABA‐immunoreactive neurons in the ipsilateral layer V were less numerous (5,600/mm3, 15.0%) than in both sides of the controls (average of 10,300/mm3, 22.0%;P<0.01).Thus, our results show that a unilateral sensory deprivation induces highly selective changes in the intracortical GABA inhibitory circuitry of both hemispheres. These changes are located directly at the input of thalamic afferents and at an output layer of corticofugal and commissural axons and could result in a profound reorganization of the excitatory and inhibitory drives of both sides of the sensory‐deprived barrel field cortex. © 1

ISSN:0092-7317    

DOI:10.1002/cne.903610403

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe circadian rhythms displayed by numerous biological functions are known to be sex specific and affected by aging. It has not been settled yet whether the sex‐ and age‐related characteristics of circadian rhythms derive from changes in the anatomy of the suprachiasmatic nucleus. To shed light on these issues, we applied unbiased stereological techniques to estimate the volume of the suprachiasmatic nucleus as well as the total number of its cells and the mean volume of their somata and nuclei in progressively older groups of male and female Wistar rats (aged 1, 6, 12, 18, 24, and 30 months). The volume of the nucleus was estimated with the Cavalieri principle on serial sections. The total numbers of neurons and astrocytes were estimated by applying the optical fractionator, and the mean somatic and nuclear volumes of cells were estimated by using isotropic, uniform random sections and the nucleator method. On average, the volume of the suprachiasmatic nucleus was 0.044 mm3, and the total number of neurons and astrocytes was 17,400. Cells of the dorsomedial and ventrolateral components of the nucleus, which are morphologically different, have identical mean perikaryal and nuclear volumes, which we estimated to be 750 μm3and 400 μm3, respectively.We further demonstrated that, at all ages analysed, the volume of the suprachiasmatic nucleus, the total cell number, and the mean somatic and nuclear volumes of its cells are affected neither by the age nor by the sex of the animal, regardless of the presence of sex‐ and age‐related variations in circadian rhythms. However, the possibility that females may display changes in the volume of the suprachiasmatic nucleus at older ages cannot be ruled out. No effect of aging was observed in the total number of neurons or in the total number of astrocytes. © 1995 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903610404

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe morphology and distribution of microglial cells were studied in the normal cerebellum of young and adult mice using the histochemical demonstration of nucleoside diphosphatase as a specific microglial marker. Our results showed that microglial cells were present in all cerebellar lobules of both young and adult mice, but their distribution and morphology were not homogeneous throughout the cerebellum. Heterogeneity in microglial cell distribution was exclusively related to their location in the different histological layers, and no significant differences were found either between the different cerebellar lobules or between young and adult mice. Microglial density was higher in the cerebellar nuclei than in the cortex; within the cortex, the molecular layer was less densely populated by microglial cells than the granular layer and the white matter. The morphological study revealed that microglial cells were ramified in all cerebellar lobules of both young and adult mice but showed different sizes and ramification patterns as a function of their specific location in the different histological layers. Several typologies of microglial cells were described on the basis of observations in both horizontal and coronal sections. The specific layer‐related pattern of microglial distribution and morphology in mouse cerebellum strongly suggests a physical and functional adaptation of these cells to the characteristics of their microenvironment. © 1995 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903610405

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe olfactory and accessory lobes in the crayfish are large spherical neuropils found on each side of its brain. The olfactory lobes receive the afferent axons of chemoreceptors that are located along the outer branches of the biramous first antennae. The accessory lobes receive a large input from interneurons whose axons lie in the deutocerebral commissure. A pair of large serotonergic neurons (the dorsal giant neurons) branch unilaterally in the accessory and olfactory lobes of each side. From physiological recordings, it has been proposed that the deutocerebral commissure interneurons synapse with elements in the accessory lobes that in turn connect to the dorsal giant neuron. It has also been proposed that the dorsal giant neuron is activated by inputs in the accessory lobe and that its output is in the olfactory lobe. This ultrastructural study tests this hypotheses by examining the polarity of synaptic terminals on dorsal giant neurons and deutocerebral interneurons that have been filled with neurobiotin. In double‐labelled preparations, we found the deutocerebral interneurons to be presynaptic to elements in the accessory lobes, but none of these postsynaptic elements was identifiable as the dorsal giant neuron. The dorsal giant neurons receive many more synaptic inputs in the accessory lobes than in the olfactory lobe. Very few giant serotonin neuron output synapses were found in either lobe. © 1995 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903610406

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractFollowing surgical deafferentation of the spinal cord, cut dorsal roots degenerate, and spared projections compensate for this loss by collateral sprouting (reactive reinnervation). Light microscopic immunocytochemistry has shown sprouting by selected undamaged intraspinal projections, including those that express the transmitters substance P and serotonin. Quantitative immunoelectron microscopy supports these results by demonstrating loss and subsequent recovery of substance P‐containing terminals and an increase in serotonin‐containing terminals. To test the hypothesis that changes in afferent innervation modulate neurotransmitter receptors on second‐order neurons, we used receptor binding autoradiography in this model. Adult rats were subjected to L1–S2 unilateral dorsal rhizotomy and killed at 1, 2, 6, or>20 weeks after surgery. Receptor binding densities of tachykinin (neurokinins‐1 and ‐3), glutamate (N‐methyl‐D‐aspartate), and serotonin (serotonin‐1a) receptors were assayed in the lumbar dorsal horn. Neurokinin‐1 binding density was increased in lamina II of the deafferented side by 1 week after surgery, remained elevated at 2 weeks, and returned to control values by 6 weeks. Neurokinin 3 binding density was elevated at 2 weeks and then returned to control levels. N‐methyl‐D‐aspartate receptor binding showed slight but not statistically significant increased binding density at 6 and at>20 weeks. No significant changes were found in serotonin‐1a receptor binding density. The elevations in tachykinin receptor binding density occur when afferents in the dorsal horn are degenerating and suggest reactive up‐regulation of the receptor. The return to normal levels coincides with reactive reinnervation in the spinal cord, which restores synaptic numbers. Changes in N‐methyl‐D‐aspartate binding occur much later than the restitution of synaptic numbers but may indicate a role for this receptor in synaptic stabilization following reactive

ISSN:0092-7317    

DOI:10.1002/cne.903610407

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractCells within the auditory brainstem of cat that respond to sound by producing the transcription factor Fos or related proteins were identified by immunostaining with antisera against Fos and Zif/268. Within the cochlear nucleus, all antisera showed similar staining patterns, however, in the superior olive and inferior colliculus, staining patterns differed between antisera. Immunostained cells were characterized by their size, location, by the presence of perisomatic terminals that immunostained for glutamate decarboxylase or synaptophysin, or by electron microscopy. Most cell classes were not immunopositive. In the ventral cochlear nucleus, roughly 99% of Fos‐positive cells had few perisomatic terminals. Within the superior olivary complex (SOC), the majority of immunopositive cells had few perisomatic terminals. Lateral olivocochlear cells were identified as Fos positive by their size, location, lack of perisomatic terminals, and positive costaining for acetylcholinesterase as evidenced by a novel reaction product. This report appears to be the first demonstration of these cells responding to sound stimulation. Within the inferior colliculus, bands of positive cells produced by tonal stimulation extended from the central nucleus throughout the dorsal cortex and the posterior pericentral region, a finding unexpected on the basis of previous electrophysiological recordings and anatomical studies of ascending inputs to the colliculus. Approximately 35% of Fos‐positive cells in the inferior colliculus had plentiful perisomatic terminals. Results demonstrate a high degree of specificity of auditory cell types that respond to sound by producing Fos‐like proteins and show that previously intractable physiological questions can be addressed by assaying for sound‐induced production of these antigens. © 1995 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903610408

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe projections of the ankle joint capsule afferents were studied by transganglionic transport of horseradish peroxidase injected directly into the ankle joint. The number and size of the labelled dorsal root ganglion cells were measured from synsacral nerves 2–9. In the dorsal root ganglia, all sizes of sensory neurones were labelled, and the largest number of labelled cells was in ganglia 5–7. The extensive sympathetic innervation of the ankle joint was identified by the large number of cell bodies labelled in the sympathetic ganglia of the paravertebral chain. Labelled afferent fibres projected to the spinal cord from the 2nd to the 8th synsacral nerves, with the rostral projection mainly via Lissauer's tract and the dorsal funiculus. Terminal labelling in the dorsal horn was identified in laminae I–III and VI, with a slight projection to V. Two areas of dense labelling, which did not correspond with the largest number of labelled dorsal root ganglion cells, were identified. A rostral area with the highest density of label was observed at the level of synsacral nerves 3–4 and a second slightly less dense area between synsacral nerves 7–8. In the caudal medulla, diffuse terminal labelling was observed in the nucleus gracilis et cuneatus, nucleus of the tractus solitarius, and the nucleus cuneatus externus.These results are discussed in a comparative context to identify similarities and differences between different primary afferent projections in birds and mammals and to highlight the possible functional significance of the avian articular afferent projection. © 1995 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903610409

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractSystemic interleukin‐1 (IL‐1) activates the hypothalamo‐pituitary‐adrenal (HPA) axis, an effect exerted through increased synthesis and secretion of corticotropin‐releasing factor (CRF) by parvicellular neurosecretory neurons. The site(s) and mechanism(s) through which circulat ing IL‐1 may access central systems governing HPA axis output remain obscure. To identify potential cellular targets for blood‐borne IL‐1, we analyzed the distribution of mRNA encoding the rat type 1 IL‐1 receptor (IL‐1R1) in rat brain. Regional ribonuclease protection assays detected a single protected fragment corresponding to the membrane‐bound form of the IL‐1R1 mRNA in all areas analyzed. In situ hybridization revealed labeling predominantly over barrier‐related cells, including the leptomeninges, non‐tanycytic portions of the ependyma, the choroid plexus, and vascular endothelium. Low to moderate levels of the IL‐1111 mRNA were detected in just a few neuronal cell groups, including the basolateral nucleus of the amygdala, the arcuate nucleus of the hypothalamus, the trigeminal and hypoglossal motor nuclei, and the area postrema. No specific labeling for IL‐1R1 mRNA was detected over neurons that respond to intravenous IL‐1β; by induction of transcription factor Fos, including hypophysiotropic CRF cells and brainstem catecholamine neurons. Injection of IL‐1β did, however, provoke induction of mRNA encoding the immediate‐early gene, NGFI‐B, but notc‐fos, in two major loci of IL‐1R1 expression, vascular endothelial cells, and the area postrema. Intravenous inection of IL‐1β acutely down‐regulated IL‐1R1 mRNA in perivascular cells, but not in neuronal cell groups. These results suggest the parenchymal sites of IL‐1R1 expression in rat to be distinct from those reported previously in mouse. The common expression in both species of an IL‐1R in non‐neuronal elements highlights the possibility that IL‐1‐mediated activation of CRF neurons may result from cytokine‐receptor interaction at vascular, and/or other barrier‐related, sites to trigger release of secondary signalling molecules in a position to interac

ISSN:0092-7317    

DOI:10.1002/cne.903610410

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractMost sympathetic postganglionic noradrenergic varicosities of the perivascular plexus of small muscular arteries in laboratory mammals make contact with the outer smcoth muscle cells of the media at neuromuscular junctions. These neurovascular junctions have most of the characteristics of those in skeletal muscle. In the rat tail artery, which bears a particularly dense perivascular plexus, many studies indicate that both purinergic and noradrenergic mechanisms underlie neurally mediated vasoconstriction. We have examined the relationship of large axonal varicosities to the smooth muscle surface of proximal parts of this vessel using three‐dimensional reconstructions from serial thin sections photographed in the electron microscope. Unlike in small arterioles, less than 50% of the large varicosities lying within 1 μm of the outer surface of this artery were found to make neuromuscular junctions. In some non‐contacting varicosities, accumulations of synaptic vesicles were aggregated toward axonal membrane which was bare of Schwann cell toward the vessel surface. Prejunctional membrane specializations were detected at 20% of contacting and 12% of non‐contacting varicosities. All of the latter lay close (<350nm) to the smooth muscle. These anatomical data suggest that, in the rat tail artery, transmitter release by exocytosis may occur from both types of varicosity. © 1995 Wiley‐

ISSN:0092-7317    

DOI:10.1002/cne.903610411

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY