摘要:

AbstractTo determine the localization in rat brain and spinal cord of individual neurons that contain the messenger RNA coding for the opioid peptide precursor preproenkephalin, we performedin situhybridization with a tritiated cDNA probe complementary to a protion of preproenkephalin mRNA. We observed autoradiographic signal over the cytoplasm of neurons of many regions of the central nervous system. Several types of controls indicated specificity of the labeling. Neurons containing preproenkephalin mRNA were found in the piriform cortex, ventral tenia tecta, several regions of the neocortex, nucleus accumbens, olfactory tubercle, caudate‐putamen, lateral septum, bed nucleus of the stria terminalis, diagonal band of Broca, preoptic area, amygdala (especially central nucleus, with fewer labeled neurons in all other nuclei), hippocampal formation, anterior hypothalamic nucleus, perifornical region, lateral hypothalamus, paraventricular nucleus, dorsomedial and ventromedial hypothalamic nuclei, arcuate nucleus, dorsal and ventral premamillary nuclei, medial mamillary nucleus, lateral geniculate nucleus, zona incerta, periaqueductal gray, midbrain reticular formation, ventral tegmental area of Tsai, inferior colliculus, dorsal and ventral tegmental nuclei of Gudden, dorsal and ventral parabrachial nuclei, pontine and medullary reticular formation, several portions of the raphe nuclei, nucleus of the solitary tract, nucleus of the spinal trigeminal tract (especially substantia gelatinosa), ventral and dorsal cochlear nuclei, medial and spinal vestibular nuclei, cuneate and external cuneate nuclei, gracile nucleus, superior olive, nucleus of the trapezoid body, some deep cerebellar nuclei, Golgi neurons in the cerebellum, and most laminae of the spinal cord. In most of these brain regions, the present results indicate that many more neurons contain preproenkephalin mRNA than have been appreciated previously on the basis of immunocytochemistr

ISSN:0092-7317    

DOI:10.1002/cne.902580202

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

年代:1987

数据来源: WILEY

摘要:

AbstractAfferents to the thalamic ventrobasal complex (VB) originating from the spinal cord, the dorsal column nuclei, and the somatosensory cortex were anterogradely labeled by WGA‐HRP 30 days after an injection of kainic acid (KA), which produced a complete unilateral neuronal loss in the VB, the opposite side being used as a control.At the light microscopic level, there was no obvious rerouting of spinal afferents away from the lesioned areas towards unlesioned parts of VB. There was an apparent decrease in the number of lemniscal afferents to the lesioned side, which may indicate a progressive retrograde degeneration. At higher magnification, all three afferent systems studied demonstrated morphological changes, predominantly manifested by terminal swellings that reached up to 25 μm in diameter. Control experiments suggested that these morphological alterations were related neither to a direct action of the excitotoxin nor to the absence of a different afferent system but to the loss of neuronal postsynaptic targets.At the electron microscopic level, the normal ultrastructural features of VB were not observed after a KA lesion. No neuronal somata, dendrites, or normal presynaptic elements were observed. Neural elements, some of which were labeled from the somatosensory cortex or the dorsal column nuclei, were essentially of two types: varicosities and unmyelinated axonal profiles. Varicosities could be separated into two broad classes: (1) The majority were large structures derived from large, sometimes myelinated, axons and containing a wealth of organelles. Since they were not completely surrounded by glial elements, we have denoted them unensheathed varicosities. Among the organelles, the most obvious features were vesicles and tubules of smooth endoplasmic reticulum, microtubules, mitochondria, and various lysosome‐like inclusions. These unensheathed varicosities gave rise to large, mound‐like protrusions containing large vacuoles and thin long protrusions either filled with neurofilaments or resembling unmyelinated axonal profiles. (2) Others were completely surrounded by a glial sheet and were therefore called ensheathed varicosities. These ensheathed varicosities presented several characteristics typical of degenerating profiles, including neurofilamentous proliferation and morphological alterations of the mitochondria. Unmyelinated axonal profiles occupied a substantial territory in the lesioned area. They were most often grouped in bundles sometimes wrapped by glial processes.The proliferation of unmyelinated fibers and the appearance of axonal varicosities are compared to the regeneration phenomena described in the literature after a lesion in the central nervous system. The hypothesis that the varicosities are growth‐cone‐like structures in the adult CNS is

ISSN:0092-7317    

DOI:10.1002/cne.902580203

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe efferent projections of the suprachiasmatic nucleus (SCh) in the rat hypothalamus have been reexamined with the anterograde tracerPhaseolus vulgarisleucoagglutinin (PHA‐L), which displays labeled axons with the clarity of a Golgi impregnation. Fibers from the SCh can be divided into six pathways for descriptive purposes. By far the densest terminal field arising from cells in the SCh ends in a roughly comma‐shaped zone between the SCh and paravontricular nucleus on the one hand and the periventricular nucleus and anterior hypothalamic area on the other. A few axons continue dorsally from this “subparaventricular zone” to pass through parvicellular parts of the paraventricular nucleus and the overlying midline thalamic nuclei to end in midrostrocaudal parts of the paraventricular nucleus of the thalamus, and a larger number continue caudally to end in the dorsomedial nucleus, dorsal parts of the cell‐sparse zone surrounding the ventromedial nucleus, and the posterior hypothalamic area. The other five pathways all consist of relatively small numbers of fibers and give rise to relatively sparse terminal fields. The second pathway consists of rostrally directed fibers that end in ventral parts of the medial preoptic area and anteroventral periventricular nucleus. The third consists of anterodorsally oriented fibers that pass through the medial preoptic nucleus and adjacent regions to end ventrally in the intermediate lateral septal nucleus. The fourth consists of fibers just caudal to the third group that end in the preoptic continuation of the bed nucleus of the stria terminalis, as well as in the parataenial nucleus and rostral part of the paraventricular nucleus of the thalamus. The fifth consists of laterally directed fibers that course over the optic tract to end in the ventral lateral geniculate nucleus. And the sixth consists of fibers that course posteriorally through the anterior hypothalamic and retrochiasmatic areas to end in the cell‐sparse zone between the arcuate nucleus and ventral parts of the ventromedial nucleus, as well as in adjacent parts of the lateral hypothalamic area.The distribution of projections labeled following PHA‐L injections centered in the subparaventricular zone was also examined and was confirmed with retrograde tracer experiments (Watts and Swanson:J. Comp. Neurol. 258:230–252, '87). The results indicate that the subparaventricular zone projects to essentially the same regions as the SCh, only much more densely, and also sends fibers back to the SCh. In addition, the subparaventricular zone innervates a much larger extent of the lateral septal nucleus than the SCh and also sends fibers throughout the length of the periaqueductal gray.The results of this study indicate that the output of the SCh may be viewed best as a two‐stage process in concert with the subparaventricular zone. Unfortunately, it is still not entirely clear how the SCh effects all manner of circadian and diurnal rhythms since it does not appear to innervate in a significant way cell groups that are known to play a direct role in somatomotor, autonomic, and neuroendocrine responses. Nevertheless, the possible functional role of cell groups innervated directly by the SCh and subparaventricular

ISSN:0092-7317    

DOI:10.1002/cne.902580204

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

年代:1987

数据来源: WILEY

摘要:

AbstractIn a previous study (Watts et al., '87) we reexamined the projections of the suprachiasmatic nucleus (SCh) with the PHA‐L method and found that they could be divided conveniently into six groups of fibers. By far the densest projection ends just dorsal to the SCh in a comma‐shaped region designated the “subparaventricular zone,” although some fibers continue on through the paraventricular nucleus of the hypothalamus to end in the overlying midline thalamus, and others continue on to end in the dorsomedial nucleus, the region around the ventromedial nucleus, and the posterior hypothalamic area. Other relatively sparse projections from the SCh were also described to the preoptic region, lateral septal nucleus, parataenial and paraventricular nuclei of the thalamus, and ventral lateral geniculate nucleus. In addition, the same method was used to show that the subparaventricular zone projects in turn massively to these same regions, as well as back to the SCh itself and to the periaqueductal gray.The present series of experiments was designed to confirm these observations with retrograde tracer injections and to investigate the cellular and possible neurotransmitter organization of the major projections from the SCh and subparaventricular zone with a combined retrograde tracer‐immunohistochemical method. For this, the distribution of neuronal cell bodies within the SCh that stain with antisera to vasopressin, vasoactive intestinal polypeptide (VIP), corticotropin‐releasing factor, bombesin, substance P, neurotensin, somatostatin, thyrotropin‐releasing hormone, and angiotensin II was described in detail first. Then the distribution of retrogradely labeled neurons that were also stained for one or another of these peptides was described after injections of true blue, or in some cases SITS, into the regions of the subparaventricular zone, the paraventricular and parataenial nuclei of the thalamus, the ventromedial nucleus, the dorsomedial nucleus, and the periaqueductal gray. The results confirm previous immunohistochemical and anterograde tracing studies and in addition indicate that cells in dorsal as well as ventral parts of the SCh project to each of the terminal fields examined, as do many cells in surrounding areas, including the subparaventricular zone. Our results also suggest that, at the very least, vasopressin‐, VIP‐, and neurotensin‐stained cells in the SCh project to the subparaventricular zone, midline thalamus, and dorsomedial nucleus, and that the vasopressin and VIP‐stained fiber systems are partially segregated at the level of the subparaventricular zone. Finally, we have shown that neuropeptide‐Y‐stained neurons in the ventral lateral geniculate nucleus (the intergeniculate leaflet) project to the same nucleus on the o

ISSN:0092-7317    

DOI:10.1002/cne.902580205

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe localization of the melatonin‐synthesizing enzyme hydroxyindole‐O‐methyltransferase (HIOMT) was examined by light and electron microscopic immunocytochemistry in the human retina. HIOMT‐like immunoreactivity was observed in the photoreceptor layers and the inner nuclear layer (INL). The immunoreactive cells in the INL were more numerous in the central retina than in the peripheral retina and sent processes to both the outer plexiform and inner plexiform layers. The HIOMT immunoreactivity in the inner plexiform layer (IPL) appeared as punctate terminals in the proximal and distal one‐thirds of that layer.At the ultrastructural level, HIOMT‐like immunoreactivity was localized to the cytoplasm of rod and cone photoreceptors and to a population of cone bipolar cells. HIOMT‐immunoreactive bipolar cell dendrites were observed to make both invaginating and flat synaptic contacts with cone pedicles. No immunoreactive invaginating contacts in rod spherules were observed. HIOMT immunoreactivity was observed in the bipolar cell cytoplasm in the INL, and in the bipolar synaptic terminals in the IPL. These terminals contained synaptic ribbons, which formed synaptic contacts with unlabeled cells in the IPL. HIOMT radioenzymatic assays confirmed the presence of HIOMT in the human retina. Average HIOMT activity of eight donors was determined to be 15.0 pmol/mg protein/hour ± 7.2 S.D. The ultrastructural localization of HIOMT observed in this study, combined with reports from other laboratories, suggests that the cytoplasm of the photoreceptors and a population of cone bipolar cells may be the sites of melatonin synthesis in th

ISSN:0092-7317    

DOI:10.1002/cne.902580206

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe anatomical localization of glutamic acid decarboxylase (GAD), the synthesizing enzyme for GABA, was analyzed in the brainstem auditory nuclei of the adult gerbil. GAD‐positive terminals and somata were present in the cochlear nucleus, superior olivary complex, lateral lemniscus, and inferior colliculus in varying concentrations and patterns. One of the highest densities of GAD‐positive terminals is found in the superficial layers of the dorsal cochlear nucleus (DCN), whereas the ventral cochlear nucleus (VCN) has somewhat fewer terminals that are arranged in pericellular plexuses. GAD‐positive neurons occur mainly in the superficial and fusiform layers of the DCN and are scattered throughout the VCN. Within the superior olivary complex, the highest concentration of immunoreactive terminals and neurons occurs in the ventral and lateral nuclei of the trapezoid body. In contrast, the medial nucleus of the trapezoid body and the medial superior olive contain fewer GAD‐positive puncta and probably no immunoreactive somata. The lateral superior olive and superior periolivary nucleus contain a few immunoreactive puncta but a large number of immunoreactive somata. In the midbrain, the nuclei of the lateral lemniscus contain a moderate number of GAD‐positive puncta and a large number of different types of GAD‐positive neurons. The inferior colliculus also contains a heterogeneous population of labeled somata, most of which are multipolar neurons. In addition, a high concentration of immunoreactive puncta occurs in this region. These data demonstrate a diverse distribution of GAD‐positive neurons and puncta throughout the brainstem auditory nuclei and suggest that GABA might be an important neurotransmitter in the processing of auditor

ISSN:0092-7317    

DOI:10.1002/cne.902580207

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

年代:1987

数据来源: WILEY

摘要:

AbstractDetailed microelectrode maps of the hand representation were derived in cortical areas 3b and 1 from a series of normal adult owl and squirrel monkeys. While overlap relationships were maintained, and all maps were internally topographic, many map features varied significantly when examined in detail. Variable features of the hand representations among different monkeys included (a) the overall shapes and sizes of hand surface representations; (b) the actual and proportional areas of representations of different skin surfaces and the cortical magnifications of representations of specific skin surfaces, which commonly varied severalfold in area 3b and manyfold in area 1; (c) the topographic relationships among skin surface representations, with skin surfaces that were represented adjacently in some monkeys represented in locations many hundreds of microns apart in others; (d) the internal orderliness of representations; (e) the completeness of representations of the dorsal hand surfaces; and (f) the skin surfaces represented along the borders of the hand representation.Owl monkey maps were, in general, internally more strictly topographic than squirrel monkey maps. In both species, area 3b was more strictly topographic and less variable than was area 1.The degree of individual variability revealed in these experiments is difficult to reconcile with the hypothesis that details of cortical maps are ontogenetically specified during a period in early life. Instead, we propose that differences in the details of cortical map structure are the consequence of individual differences in lifelong use of the hands. This conclusion is consistent with earlier studies of the consequences of peripheral nerve transection and digital amputation, which revealed that cortical maps are dynamically maintained and are alterable as a function of use or nerve injury in these monkeys (Merzenich et al., '83a, b, '84a; Merzenich, '86; Jenkins et al., '84; Jenkins and Merzenich, '87).

ISSN:0092-7317    

DOI:10.1002/cne.902580208

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

年代:1987

数据来源: WILEY

摘要:

AbstractReceptive fields defined for small clusters of neurons within the middle cortical layers of area 3b differed little in size or in the skin locations represented among: (a) alert, (b) nitrous oxide‐anesthetized, (c) deep sodium pentobarbital‐anesthetized, and (d) ketamine‐anesthetized owl monkeys. Repeated recordings from nearly identical cortical loci yielded nearly identical multiunit receptive fields under different conditions of anest

ISSN:0092-7317    

DOI:10.1002/cne.902580209

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

年代:1987

数据来源: WILEY

摘要:

AbstractMorphological aspects of four different groups of Golgi impregnated brain cells from a tetraploid strain ofXenopus laevisfrogs were compared to analogous cells in comparably sized diploid frogs. The cells examined included neurons from the telencephalon, caudal hypothalamus, and optic tectum, and radial glial cells from the optic tectum. The brains of tetraploid frogs appeared grossly normal and were the same size and contained similar cell types as diploid brains. As observed in previous studies on polyploid amphibia, somal diameters increased significantly in tetraploid cells for each of the four groups of cells examined. Also, the total length of the dendritic arbors in tetraploid brain cells increased significantly by factors ranging from 1.4 to 2.4 times the total length of the analogous processes in diploid cells. Tetraploid neurons in the telencephalon and hypothalamus increased their arbor lengths predominantly by increasing the number of dendritic branches, while maintaining the average distance between branch points in the dendritic segments. In contrast, the tetraploid large pear‐shaped neurons in the optic tectum had significantly longer terminal dendritic segments than the analogous diploid neurons, although these tetraploid neurons maintained their average number of dendritic segments per cell. Tetraploid tectal radial glial cells appeared to increase both their number of branches and the lengths of their terminal segments. Thus, the mode by which tetraploid brain cells achieved longer dendritic arbors varied from cell type to cell type. These results suggest a hypothetical basis for possible effects of genomic size on vertebrate brain structure and evolution at the cellular leve

ISSN:0092-7317    

DOI:10.1002/cne.902580210

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

年代:1987

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902580201

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

年代:1987

数据来源: WILEY