摘要:

AbstractThe central nervous system has been traditionally regarded as an immunologically privileged area. This feature has been in part attributed to the blood‐brain barrier, which provides a restrictive interface to circulating immunoglobulins (IgG). Recent kinetic studies suggest that the barrier to immune proteins is not absolute, but rather may be regulated by a specific transfer mechanism. In this study, we confirm the presence of IgG in the central nervous system by immunocytochemistry and demonstrate a close anatomical relationship between the distribution of this protein and the blood‐brain barrier.IgG was immunolocalized in the normal rat brain by using monoclonal and polyclonal antibodies to IgG and its subclasses. On the basis of an initial evaluation, the most appropriate antibodies and dilutions were selected for subsequent analyses. In the first study, IgG and albumin were immunolocalized in adjacent sections. In the second study, horseradish peroxidase (HRP) was given intravenously prior to sacrifice, in order to examine artifacts related to perfusion fixation. The distribution of HRP and IgG was then examined in adjacent sections. In the third study, IgG was immunolocalized in sections of brain after mild traumatic head injury.A monoclonal antibody to IgG2a and a polyclonal antibody to IgG were selected on the basis of specificity and consistent, mutual localization. Distinct, patchy, perivascular staining, infrequently associated with labeled neurons, was noted throughout the brain. Electron microsocopy confirmed the perivascular localization; IgG was localized along the basal lamina of microvasculature and within the adjacent parenchyma. Albumin and HRP did not exhibit a similar pattern of perivascular immunostaining. After head injury, prominent immunostaining for IgG was observed in the injured hemisphere.In summary, these data indicate that the normal rat brain contains IgG, which dramatically increases after head injury. The distinct perivascular distribution in the normal brain suggests local microvascular permeability. This permeability is selective for IgG, since albumin does not share a similar perivascular localization. The neuronal staining which is closely associated with perivascular label may reflect one intracellular route for extravasated IgG. © 1994 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903420402

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

年代:1994

数据来源: WILEY

摘要:

AbstractWe have investigated the distribution of cholinergic perikarya and fibers in the brain of the pigeon (Columba livia). With this aim, pigeon brain sections were processed immunohistochemi‐cally by using an antiserum specific for chicken choline acetyltransferase. Our results show cholinergic neurons in the pigeon basal telencephalon, the hypothalamus, the habenula, the pretectum, the midbrain tectum, the dorsal isthmus, the isthmic tegmentum, and the cranial nerve motor nuclei. Cholinergic fibers were prominent in the dorsal telencephalon, the striatum, the thalamus, the tectum, and the interpeduncular nucleus. Comparison of our results with previous studies in birds suggests some major cholinergic pathways in the avian brain and clarifies the possible origin of the cholinergic innervation of some parts of the avian brain. In addition, comparison of our results in birds with those in other vertebrate species shows that the organization of the cholinergic systems in many regions of the avian brain (such as the basal forebrain, the epithalamus, the isthmus, and the hindbrain) is much like that in reptiles and mammals. In contrast, however, birds appear largely to lack intrinsic cholinergic neurons in the dorsal (“neocortex‐like”) parts of the telencephalon. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903420403

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe tracer, cholera toxin‐horseradish peroxidase, was used to determine the dendritic architecture and organization of hypoglossal motoneurons in the rat. In 22 animals, the tracer was injected unilaterally into either the geniohyoid, genioglossus, hyoglossus, or styloglossus muscle. Within the hypoglossal nucleus, motoneurons innervating the extrinsic tongue muscles were functionally organized. Geniohyoid and genioglossus motoneurons were located within the ventrolateral and ventromedial subnuclei, respectively, while hyoglossus and styloglossus motoneurons were located within the dorsal subnucleus.Motoneurons located in all subnuclear divisions were found to have extensive dendrites that extended laterally into the adjacent reticular formation and medially to the ependyma. Less extensive extranuclear dendritic projections were found in the dorsal vagal complex and median raphe. Prominent rostrocaudal and mediolateral dendritic bundling was evident within the ventral subnuclei and dorsal subnucleus, respectively. Dendritic projections were also found extending inter‐ and intrasubnuclearly with a distinct pattern for each muscle.These data suggest that the varied and extensive dendritic arborizations of hypoglossal motoneurons provide the potential for a wide range of afferent contacts for, and interactions among, motoneurons that could contribute to the modulation of their activity. Specifically, the prominent dendritic bundling may provide an anatomic substrate whereby motoneurons innervating a specific muscle receive and integrate similar afferent input and are thus modulated as a functional unit. In contrast, the extensive intermingling of both inter‐ and intrasubnuclear dendrites within the hypoglossal nucleus may provide a mechanism for the coordination of different muscles, acting synergistically or antagonistically to produce a tongue movement. © 1994 Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903420404

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

年代:1994

数据来源: WILEY

摘要:

AbstractArea V2 of macaque visual cortex represents an important but poorly understood stage in visual processing. To provide a better understanding of the region, we studied the organization of its intrinsic cortical connections by making focal (200–300 μm) iontophoretic microinjections of the tracer biocytin. Alternate tissue sections were tested for biocytin, cytochrome oxidase (CO), or Cat‐301 immunoreactivity to localize biocytin label relative to the three stripelike compartments that characterize this area. Biocytin‐labeled pyramidal neurons of layers 2/3, and, to a lesser extent, layer 5, provided laterally spreading axon projections that terminated in discrete patches (250–300 μm diameter), primarily in layers 1–3. Any injected locus in V2 projected to 10–15 similarly sized patches, up to 4 mm from the injection site, and distributed in an elongated field orthogonal to the stripe compartments. We noted prominent patchy connections within, as well as between, individual compartments, perhaps reflecting functional substructures within stripes. Each stripe compartment projected to all three compartments but with different relative frequencies; CO‐rich compartments projected mainly to other CO‐rich compartments (75%), whereas CO‐poor compartments projected equally to CO‐rich and CO‐poor compartments. We therefore emphasize the existence of substantial interconnections amongallthree V2 compartments. As further evidence for crosstalk between visual channels, we also noted an input to the V2 “thick” CO stripes from V1 cells in layer 4A as a distinct population in addition to the neurons of layer 4B. Thus, the CO stripe architecture may not be a marker for strictly segregated parallel visual pathways through

ISSN:0092-7317    

DOI:10.1002/cne.903420405

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

年代:1994

数据来源: WILEY

摘要:

AbstractImmunocytochemical techniques were used to characterize the neuronal populations in the hippocampal subplate and marginal zone from embryonic day 13 (E13) to postnatal day 5 (P5). Sections were processed for the visualization of microtubule‐associated protein 2 (MAP2) and other antigens such as neurotransmitters, neuropeptides, calcium‐binding proteins and a synaptic antigen (Mab SMI81). At E13–E14, only the ventricular zone and the primitive plexiform layer were recognized. Some cells in the later stratum displayed MAP2‐, γ‐aminobutyric acid (GABA)‐and calretinin immunoreactivities. From E15 onwards, the hippocampal and dentate plates became visible. Neurons in the plexiform layers were immunoreactive at E15–E16, whereas the hippocampal and dentate plates showed immunostaining two or three days later. Between E15 and E19 the following populations were distinguished in the plexiform layers: the subventricular zone displayed small neurons that reacted with MAP2 and GABA antibodies; the subplate (prospective stratum oriens) was poorly populated by MAP2‐ and GABA‐positive cells; the inner marginal zone (future stratum radiatum) was heavily populated by multipolar GABAergic cells; the outer marginal zone (stratum lacunosum‐moleculare) displayed horizontal neurons that showed glutamate‐ and calretinin immunoreactivities, their morphology being reminiscent of neocortical Cajal‐Retzius cells. Thus, each plexiform layer was populated by a characteristic neuronal population whose distribution did not overlap. Similar segregated neuronal populations were also found in the developing dentate gyrus. At perintal stages, small numbers of neurons in the plexiform layers began to express calbindin D‐28K and neuropeptides. During early postnatal stages, neurons in the subplate and inner marginal zones were transformed into resident cells of the stratum oriens and radiatum, respectively. In contrast, calretinin‐positive neurons in the stratum lacunosum‐moleculare disappeared at postnatal stages. At E15–E19, SMI81‐immunoreactive fibers were observed in the developing white matter, subplate and outer marginal zone, which suggests that these layers are sites of early synaptogenesis. At PO‐P5, SMI81 immunoreactivity became homogeneously distributed within the hippocampal layers.The present results show that neurons in the hippocampal subplate and marginal zones have a more precocious morphological and neurochemical differentiation than the neurons residing in the principal cell layers. It is suggested that these early maturing neurons may have a role in the targeting of hippocampal afferents, as subplate cells do in the developi

ISSN:0092-7317    

DOI:10.1002/cne.903420406

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

年代:1994

数据来源: WILEY

摘要:

AbstractUndernutrition during early life is known to cause deficits and distortions in brain structure. However, it remains uncertain whether this includes a diminution of the total numbers of neurons. Recent advances in stereological techniques have made it possible to obtain unbiased estimates of total numbers of cells in well‐defined biological structures. Rats were undernourished from day 16 of gestation to 30 postnatal days of age by standardized procedures. These rats and well‐fed control rats were anaesthetized and killed by intracardiac perfusion with fixatives at 70 days of age. The left cerebral hemisphere from each animal was embedded in Paraplast and serially sectioned. The sections were analyzed via the Cavalieri principle to obtain the total cortical volume and by the “disector” method to estimate the numerical density of neurons in the cortex. These values were later used to compute estimates of the total number of cortical neurons for each animal. Well‐fed control rats had 26.9 million cortical neurons, while the previously undernourished animals had 24.8 million. The difference between these two groups was not statistically significant. It therefore appears that undernutrition of rats during early postnatal life does not affect the total numbers of neurons in the cerebral cortex. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903420407

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe aim of this study was to examine anatomical evidence in cats of whether the nucleus reticularis parvicellularis (Pc) is part of the circuit responsible for the inhibition of brainstem motoneurons during paradoxical sleep. For this purpose, we made iontophoretic injections of the retrograde and anterograde tracer cholera toxin B subunit (CTb) in the Pc.After CTb injections in the Pc, a large number of retrogradely labeled neurons were seen in the central nucleus of the amygdala, the lateral part of the bed nucleus of the stria terminalis, the posterior hypothalamic areas, the mesencephalic reticular formation, the nucleus locus subcoeruleus, the nucleus pontis caudalis, other portions of the Pc, the nucleus reticularis dorsalis, the trigeminal sensory complex, and the nucleus of the solitary tract. We further found that the Pc receives (1) serotoninergic afferents from the raphe dorsalis, magnus, and obscurus nuclei; (2) noradrenergic inputs from the dorsolateral pontine tegmentum; (3) cholinergic afferents from the lateral medullary reticular formation; (4) substance P‐like afferents from the central nucleus of the amygdala, bed nucleus of the stria terminalis, periaqueductal gray, and nucleus of the solitary tract; and (5) methionine‐enkephalin‐like projections from the periaqueductal gray, the nucleus of the solitary tract, the lateral pontine and medullary reticular formation, and the spinal trigeminal nucleus. We further found that the Pc do not receive afferents from brainstem structures responsible for muscle atonia, such as the ventromedial medulla and the dorsomedial pontine tegmentum, and therefore may not be part of the circuit inhibiting the brainstem motoneurons during paradoxical sleep. © 1994 Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903420408

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

年代:1994

数据来源: WILEY

摘要:

AbstractNitric oxide has been proposed as an inhibitory transmitter molecule that plays a role in muscle relaxation and vasodilation in the gastrointestinal tract. The present study analyzes the distribution of nitric‐oxide‐producing neurons in the monkey and human digestive system by means of nicotinamide‐adenine‐dinucleotide‐phosphate‐diaphorase histochemistry. This histochemical method is reliable and convenient for the visualization of neuronal nitric‐oxide synthase, the enzyme responsible for nitric‐oxide generation. In the gastrointestinal tract, nitric‐oxide‐synthase‐related diaphorase activity was present in nerve fibers running through‐out the muscle layer (circular>longitudinal) and in numerous ganglion cells and processes in the myenteric plexus of monkeys and humans. Labelled ganglion cells and fibers also were observed in the submucous plexus, although they were much less numerous than those seen in the myenteric plexus. In the submucosa, a few positive fibers were seen around blood vessels. In the mucosa, stained fibers were sparse at the base of the villi and crypts, whereas they were quite abundant in the muscularis mucosae, especially in the small intestine and colon. In the gallbladder (human), labelling was found in ganglion cells and processes of the innermost and outermost ganglionated plexuses. Stained fibers also were distributed to the muscular layer and, less abundantly, to the mucosa and vasculature. Labelled fibers were more abundant in the sphincter of Oddi (human) than in the gallbladder. In the monkey and human pancreas, nicotinamide‐adenine‐dinucleotide‐diaphorase staining was seen mainly in ganglion cells and fibers of intrapancereatic ganglia, and in processes running among acini, around ducts and in the stroma. A moderate density of stained fibers also was distributed to the vasculature, whereas the islets showed few positive processes. Finally, double label experiments performed in the pancreas showed that the vast majority of neurons producing intric oxide are immunoreactive for vasoactive intestinal peptide.The present results demonstrate that in the digestive tract of primates nitric‐oxide neurons and processes are widespread. This supports the hypothesis that neural nitric oxide plays a broader role than smooth‐muscle relaxation and vasodilation in the periphery. It may be involved in neuronal communication within the enteric plexuses and may influence different digestive functions including endocrine and exocrine s

ISSN:0092-7317    

DOI:10.1002/cne.903420409

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

年代:1994

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.903420401

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

年代:1994

数据来源: WILEY