ISSN:0092-7317    

DOI:10.1002/cne.902810302

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe organization of the cholinergic innervation of the macaque monkey amygdaloid complex was investigated by means of immunohistochemical techniques and either a polyclonal antiserum or a monoclonal antibody directed against the specific synthetic enzyme choline acetyltransferase (ChAT). Adjacent series of sections were processed histochemically for the demonstration of the degradative enzyme acetylcholinesterase (AChE) or for cell bodies with thionin. The density of ChAT immunoreactivity differed substantially among the various nuclei and cortical regions of the amygdala. In general, the distribution of ChAT immunoreactivity paralleled the pattern of AChE staining. One notable exception was the presence of AChE containing cell bodies in addition to AChE positive fibers within nearly all of the nuclear and cortical regions. In contrast, ChAT immunoreactivity was associated only with fibers and terminals.The highest density of ChAT immunoreactive fibers and terminals was consistently observed in the magnocellular subdivision of the basal nucleus. Staining was substantially less dense in the more ventrally situated parvicellular subdivision. Medially, in the adjacent accessory basal nucleus, immunoreactive fibers and terminals were densest in the magnocellular and superficial subdivisions and least prominent in the parvicellular subdivision. Of the deep nuclei, the lateral nucleus generally contained the least ChAT immunoreactive terminals and processes. Only its more densely cellular ventrolateral portion contained appreciable fiber and terminal staining.One of the more distinctive patterns of ChAT immunoreactivity was seen in the nucleus of the lateral olfactory tract. Here, ChAT positive fibers formed pericellular basket plexuses around unstained cell bodies. This unique pattern of staining was used to delineate the boundaries of the nucleus and indicated that it is present for much of the rostrocaudal extent of the amygdala. Another region of conspicuous staining on the medial surface of the amygdala was the sulcal portion of the periamygdaloid cortex. This region, associated with the sulcus semiannularis and bordering the entorhinal cortex, consistently contained dense immunoreactivity. The central nucleus also presented a somewhat idiosyncratic pattern of ChAT staining. The lateral subdivision had a diffuse distribution of immunoreactivity in which focal patches of more densely stained terminals and occasional fine fibers were embedded. In contrast, the medial subdivision contained a larger number of thicker, stained fibers without diffuse background labeling. Of the remaining amygdaloid nuclei, the amygdalohippocampal area contained dense ChAT staining, whereas progressively lighter staining was seen in anterior amygdaloid, posterior cortical, anterior cortical, and medial nuclei.

ISSN:0092-7317    

DOI:10.1002/cne.902810303

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe distribution of dopamine‐containing cell bodies and fibers was studied with aid of specific antibodies against dopamine in the highly developed brain of the weakly electric fishGnathonemus petersii.In the telencephalon, dopamine‐containing cell bodies were observed in a small area, i.e., area ventralis pars dorsalis and supracommissuralis. In the diencephalon, moderate numbers of dispersed dopamine‐immunoreactive cells were present in the preoptic region, while large numbers of dopamine‐containing neurons occurred in the hypothalamic paraventricular organ and neighbouring regions. The paraventricular organ, located around small (anterior, intermediate, and posterior) recesses contained many dopamine‐immunoreactive cerebrospinal fluid‐(CSF)‐contacting neurons. Dopamine‐containing cells were also observed in a magnocellular hypothalamic cell group, in the nucleus of the lateral recess, and in the nucleus posterior tuberis. In the mesencephalon only a few dopamine‐containing cells were observed in a dorsal tegmental (possibly pretectal) area, whereas in ventral mesencephalic regions dopamine‐containing cells were lacking. More caudally, dopamine‐containing cells were observed in the presumed locus coeruleus, in the caudal region of the reticular formation, and in the presumed area postrema.Dopamine‐immunoreactive fiber density was very high in the medioventral hypothalamus and in the preoptic region, where a dense subependymal plexus was observed along the preoptic recess. Such a plexus was also present in the caudal rhombencephalon, where it probably arises from the area postrema. Moderate numbers of dopamine‐immunoreactive fibers were present in medioventral parts of the brain along its total rostrocaudal extent as well as in several subnuclei of the torus semicircularis, in the tectum mesencephali, and in the medial part of the dorsal telencephalic area. Other parts of the dorsal telencephalic area, as well as the large cerebellum and the electrosensory lateral line lobe ofGnathonemus, did not contain detectable amounts of dopamine.In spite of the high differentiation of the brain ofGnathonemus, the distribution of catecholamines as visualized with dopamine immunohistochemistry appears to be basically similar to that described in other teleostean and actinopterygian fishes on the basis of formaldehyde‐induced fluorescence or tyrosine hydroxylase immunohistochemistry. However, the absence of a mesencephalostriatal dopamine system and the presence of a very dominating and complex periinfundibular dopamine system indicate basic differences between actinopterygians and other anamniote (elasmobranch) as well as amniote groups (e.g., reptiles and mammals). Since many CSF‐contacting neurons in the infundibular paraventricular organ seem to lack the dopaminesynthesizing enzyme tyrosine hydroxylase, we suggest that a substantial part of the teleostean paraventricular organ might receive dopamine from the intraventricular CSF, into which it might be released by the

ISSN:0092-7317    

DOI:10.1002/cne.902810304

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe distribution of atrial natriuretic factor (ANF) binding sites was investigated in the central nervous system of the frogRana ridibundausing the technique of in vitro receptor autoradiography by means of [125I]‐labeled ANF‐28. The anatomic distribution of ANF recognition sites was determined on Kodak ARX films apposed onto tissue sections, and their distribution was examined in greater detail by analysis of autoradiograms generated by using emulsion‐coated sections. The highest levels of ANF binding sites were found in the olfactory bulb, the dorsal pallium, the septum, the habenular nucleus, the dorsal infundibular nucleus, the interpeduncular nucleus, and in the tectum. Moderate levels of ANF binding sites were observed in the thalamus and throughout the mesencephalon, whereas low levels were detected in the lateral and medial pallium, the medial forebrain bundle, and the nucleus rotondus. In the pituitary gland, the neural and distal lobes were densely loaded with ANF binding sites, whereas no autoradiographic labeling was observed in the pars intermedia. In general, there was a good correlation between the location of ANF receptors and the distribution of ANF‐containing neurons, as previously determined by immunocytochemistry. Together these results support the view that ANF may act as a neurotransmitter or a neuromodulator in various regions of the fro

ISSN:0092-7317    

DOI:10.1002/cne.902810305

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe topographical distribution, histochemical characteristics, and anatomical relationships of the cellular elements containing choline acetyltransferase (ChAT) immunoreactivity, demonstrated with specific monoclonal antibodies to ChAT following the unlabelled antibody peroxidase‐antiperoxidase (PAP) procedure at the optical and electron microscopic levels, were investigated in the rat substantia nigra (SN).Scarce, large (20–30 μm in maximum soma extent) cholinergic cell bodies and processes were found within the boundaries of the SN, in the borders of the pars compacta and pars reticulata, principally at caudal levels. Occasionally, cholinergic neurons were also found at intermediate levels of the SN, in the borders of the pars reticulata and pars lateralis. Cytologically, these large cells resembled ChAT‐positive neurons localized in other areas of the central nervous system (CNS) of the rat—for example, the pontomesencephalotegmental (PMT) cholinergic complex (Ch5‐Ch6) and the nucleus basalis of Meynert (nbM) (Ch4).Histochemically, ChAT‐positive cells in the SN were characterized by their ability to utilize the reduced cofactor nicotinamide adenine dinucleotide phosphate (NADPH).Identified ChAT‐positive neurons in the light microscope were subsequently studied in the electron microscope. All cholinergic neurons in the SN share essentially the same ultrastructural characteristics. The copious cytoplasm was rich in organelles with large lipofuscin granules. The synaptic input onto cell bodies and their dendrites was studied in serial sections. Synaptic contacts onto the perikarya and proximal dendrites were sparse and of asymmetric type. Both symmetric and asymmetric synaptic specializations onto ChAT‐positive distal dendrites were detected. Asymmetric synaptic contacts onto cell bodies and dendrites were often defined by the presence of subjunctional dense bodies associated with the postsynaptic membrane. The pattern of the synaptic input to these cells differs strikingly from that onto unlabelled neighboring neurons. The perikarya and dendrites of the latter were characteristically covered with synaptic boutons.Scarce immunoreactive terminals in asymmetric synaptic contact with unlabelled dendritic profiles were also detected in portions of SN compacta with no ChAT‐positive cells.Extranigrally located ChAT‐positive cells of the PMT cholinergic complex were also examined in the electron microscope for comparison purposes. These cells exhibited, on the basis of their morphology and synaptic input pattern, very similar characteristics to those shown by SN cholinergic neurons.On the basis of histochemical and morphological comparison between nigral cholinergic neurons and extranigrally located ChAT‐positive cells of the PMT complex, it is concluded that cholinergic neurons in the SN of the rat may be projection neurons of the PMT cholinergic complex ectopically located and that they might play an important role in the regulation of forebrain activation and in locomotion. Our electron microscopic results suggest that substance P and GABA may influence the f

ISSN:0092-7317    

DOI:10.1002/cne.902810306

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

年代:1989

数据来源: WILEY

摘要:

AbstractIn the frog, peripheral muscle axons regenerate after a lesion to reinnervate the original synaptic sites on muscle fibers. Previous experiments in the frog have shown that satellite cells of the nerve tube direct the outgrowth of regenerating muscle axons over distances of many millimeters. In the present experiments, denervated muscle was used as a target for regenerating muscle axons. Muscle and satellite cells of the nerve tube also were placed in filters to determine if their influence on axonal outgrowth was exerted by diffusible factors. Filters were used with a pore size of 0.22 μm. With this pore size, target cells were isolated from physical contact with the surrounding cells; yet an exchange of fluids–and therefore of molecules released by the target cells–could occur across the filter.In the presence of denervated muscle or satellite cells of the nerve tube in filters, regenerating axons turn and grow toward the target cells. This influence on the direction of axonal outgrowth was produced over distances of 6 mm by muscles and 4 mm by cells of the nerve tubes. This directed outgrowth is in marked contrast to the random pattern of outgrowth in the absence of the targets.The present findings set the stage for tissue culture experiments in which the phenomena observed in vivo can be analyzed in terms of mechanisms. The present finding that denervated muscle attracts regenerating axons means that sufficient material may be available for the characterization and isolation of the relevant molec

ISSN:0092-7317    

DOI:10.1002/cne.902810307

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

年代:1989

数据来源: WILEY

摘要:

AbstractConnections of visual cortex in squirrels were investigated by placing WGA‐HRP injections, and in some cases fluorescent dyes, into area 17 (V‐I) or area 18 (V‐II). Results were related to architectonic fields determined in brain sections cut parallel to the surface of manually flattened cortex and to limited microelectrode mapping data. Injections in area 17 provided evidence for (1) a patchy pattern of horizontal intrinsic connections extending 1–2 mm form the injection site; (2) uneven, widely distributed connections with area 18 (V‐II) and adjoining occipital‐temporal (OT) cortex; and (3) callosal connections of large portions of area 17 with the 17/18 border zone. While restricted locations in area 17 had uneven interconnections over several mm of area 18, more rostral locations in area 17 related to more rostral locations in area 18, demonstrating a topographic tendency. Injections in area 18 revealed (1) zones of discontinuous connections with area 17 that followed a topographic pattern, (2) patches of intrinsic connections that spread over distances of up to 6–8 mm from the injection site; (3) two zones of uneven connections with OT cortex suggesting the locations of at least two visual areas, OTrand OTc; (4) connections with limbic cortex rostromedial to areas 17 and 18; (5) sparse connections with regions of temporal cortex lateral to OT; and (6) uneven callosal connections with area 18 and OT cortex. The widespread and unevenly distributed intrinsic callosal interconnection patterns of areas 17 and 18 contrast with the restricted excitatory receptive fields of neurons and the retinotopic patterns of representation in these fields. Although physiological evidence is presently lacking, the patchy connections suggest that areas 17 and 18 in squirrels are modula

ISSN:0092-7317    

DOI:10.1002/cne.902810308

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

年代:1989

数据来源: WILEY

摘要:

AbstractAfter transection of the optic nerve of adult rats, most of the axons in the proximal stump die and the surviving ones are unable to regenerate into the distal optic nerve. Since the fetal brain has an inherent capacity to regenerate axons, we investigated whether fetal (E16) target regions of optic axons (thalamus and tectum) transplanted to the completely transected optic nerve of adult rats would promote axon regeneration. In control operated rats, axon growth beyond the site of transection was restricted to a few fibers that grew irregularly within the connective tissue scar. By contrast, in grafted animals directed outgrowth of optic axons toward the transplant started at 6 days postoperation (p.o.) and reached its maximum 15 days p.o. and later, when numerous single optic fibers and small axon fascicles had grown toward and into the graft, where they formed arborizations and terminal varicosities. Regenerating optic axons were further advanced than GFAP‐positive strands of astroglia that emanated from the proximal optic nerve stump. Laminin immunoreactivity appeared at 6 days p.o. in the zone of reactive astroglia in the terminal part of the optic nerve stump. Later it showed a distribution complementary to the pattern of GFAP immunoreactivity, which it seemed to circumscribe. There was no unequivocal codistribution of laminin immunoreactivity with regenerating axons.In further experiments, target regions from different ontogenetic stages (E14 to neonate and adult) and nontarget regions (E16, cerebral cortex or spinal cord) were grafted to the optic nerve stump. With the exception of the adult grafts, all transplants had effects on axon regeneration comparable to those of E16 target regions. In order to test the effects of extracellular matrix molecules on axon regeneration, a basement membrane gel reconstituted from individual components of the Engelbreth‐Holm‐Sarcoma (EHS) sarcoma was implanted between proximal and distal optic nerve stumps. No axons were induced to regenerate by this matrix. Likewise, laminin adsorbed to nitrocellulose paper and implanted at the lesion site did not stimulate axon growth from the proximal optic nerve stump.These results indicate that fetal brain is able to induce and direct regrowth of axons from the optic nerve toward the graft across a substrate that is not composed of astroglia or basement membrane components like laminin. The directed growth of axons in the absence of a preformed substrate implies a chemotactic growth response along a concentration gradient mediated by neurotropic molecules released from the

ISSN:0092-7317    

DOI:10.1002/cne.902810309

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

年代:1989

数据来源: WILEY

摘要:

AbstractAfter intraorbital transection of the optic nerve of adult rats, 90% of the retinal ganglion cells die within 30 days. Since fetal brain extracts and cocultured fetal target regions support the survival of retinal ganglion cells in vitro (Nurcombe and Bennett:Exp. Brain Res. 44: 249–258, '81; McCaffery et al.:Exp. Brain Res. 48: 377–386, '82; Armson and Bennett:Neurosci. Lett. 38: 181–186, '83) we investigated whether cell death in the adult retina could be prevented by transplanting fetal (E16) thalamus and tectum to the proximal stump of the optic nerve of adult rats that was completely transected 2–3 mm behind the optic disc. Unoperated eyes contained 119,973 (±939, SEM) retinal ganglion cells, estimated from axon counts of the intact optic nerve. Of these, 11,601 (±1,857) remained in control operated eyes at 30 days postoperation while in the eyes of grafted rats, 35,086 (±2,278) retinal ganglion cells were counted. Thus, 23,485 (=22% of those normally dying after transection of the optic nerve) ganglion cells were rescued by the fetal grafts from cell death normally following axotomy.These results indicate that fetal target regions of retinal ganglion cells contain and/or produce neurotrophic molecules that promote the survival of adult axotomized retinal gang

ISSN:0092-7317    

DOI:10.1002/cne.902810310

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe light and electron microscopic localization of antigenic sites for a polyclonal antiserum directed against the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH), was examined in the hippocampal formation of the rat brain with a double‐bridged peroxidase‐antiperoxidase method. By light microscopy, the majority of varicose processes with intense TH‐like immunoreactivity (LI) were contained in the hilus of the dentate gyrus (DG) and strata radiatum and lacunosum‐moleculare of the CA3 region of the hippocampus. Only a few immunoreactive fibers were observed in the molecular and granule cell layers of the DG, in strata oriens and pyramidale of CA3, and in all layers of CA1. Electron microscopy confirmed that these labeled processes were primarily axons and axon terminals. Terminals with TH‐LI were 0.4–1.1 μm in diameter and contained many small clear vesicles and from 0 to 3 larger densecore vesicles. The number and types of associations formed by terminals with TH‐LI were remarkably similar in the DG and hippocampus proper despite known differences in intrinsic cells and function. In both regions, the majority of terminals with TH‐LI formed junctions on small (distal) dendrites (52% of 112 in the DG; 67% of 116 in CA3) and dendritic spines (30% in the DG; 18% in CA3) that were both asymmetric and symmetric. In the DG, axosomatic junctions (2% of 112) were symmetric and occurred exclusively on the perikarya of granule cells, whereas junctions on large (proximal) dendrites were more numerous (16%), exhibited symmetric as well as asymmetric membrane specializations, and were of both granule (molecular layer) and nongranule (hilus) cell origin. In CA3, synaptic contacts on perikarya (5% of 116) and large (proximal) dendrites (10%) of both pyramidal cell and nonpyramidal cell origin were few and all symmetric. The distribution and types of synaptic associations formed by terminals with TH‐LI in the CA1 region paralleled that seen in the CA3 region. In both the dentate and hippocampus proper, 10% of the terminals with TH‐LI were observed closely apposed to unlabeled terminals that formed asymmetric synapses with dendrites and dendritic spines. In rare instances, TH‐immunoreactive terminals were found in close association with the basement membrane of blood vessels, astrocytic processes, or with other unlabeled terminals not forming recognizable junctions. In addition THLI was occasionally detected within the cytoplasm of a minority of astrocytes. These results provide the first ultrastructural evidence that TH‐immunoreactive terminals form direct synaptic contacts of both the symmetric and asymmetric types principally with distal dendrites and spines in three major subdivisions of the hippocampal formation. They thus provide a cellular substrate for the global and diverse modulation of hippocampal function by norepinephrine, the major catecholamine in this region. The additional localization of THLI in isolated glial cells suggests either (1) an unknown source of catecholamines or (2) sequence homologies between TH and another polypeptide or protein within a few astrocytes

ISSN:0092-7317    

DOI:10.1002/cne.902810311

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

年代:1989

数据来源: WILEY