摘要:

AbstractThis study reports (1) a nonhomogeneous distribution of three morphologically distinct, corticotropin‐releasing factor (CRF)‐immunoreactive axonal phenotypes within the cerebellum of the opossum: climbing fibers, mossy fibers, and beaded fibers within the ganglionic plexus; (2) the existence of CRF binding sites within the cerebellar cortex; and (3) the distribution of CRF‐containing neurons in brainstem precerebellar nuclei identified with immunohistochemistry and in situ hybridization histochemistry. CRF‐immunoreactive climbing and/or mossy fibers were identified within all cerebellar lobules. The density of CRF‐immunoreactive fibers was greatest in the vermis, where longitudinal bands of intensely immunoreactive climbing and mossy fibers were interspersed with regions containing fibers demonstrating lower levels of immunolabeling. CRF‐immunoreactive fibers were present within all deep cerebellar nuclei. The topography of CRF‐containing cerebellar fibers is discussed with respect to possible sites of origin within the brainstem. CRF‐immunoreactive neurons were identified in all nuclei of the inferior olivary complex, although the number and intensity of immunostaining of CRF‐containing cells varied within and among individual nuclei. CRF‐immunoreactive somata were also present in brainstem nuclei known to give rise to cerebellar mossy fibers. In situ hybridization histochemistry utilizing an35S‐labeled synthetic 48‐base oligodeoxynucleotide complementary to amino acids 22–37 of rat CRF proper revealed that CRF mRNA is transcribed in precerebellar nuclei. Variation in the level of CRF mRNA was detected among inferior olivary nuclei, in correspondence with variations detected in the levels of immunostaining. Data from this study suggest that variation in the level of CRF immunoreactivity detected within cerebellar afferent fibers may correlate with the level of CRF mRNA within cell bodies of origin of the projections. In vitro receptor autoradiography, utilizing125I‐Tyro‐ovine CRF, revealed correspondence between CRF binding sites and CRF‐immunoreactive fibers in the cerebellar cortex. Results of this study support suggestions for CRF‐med

ISSN:0092-7317    

DOI:10.1002/cne.902800402

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractElectrical stimulation of the preganglionic cervical sympathetic trunk causes an increase in dopa synthesis in the postganglionic neurons in the superior cervical ganglion (SCG). This transsynaptic biochemical effect can be blocked only partially by cholinergic antagonists, suggesting the involvement of a noncholinergic preganglionic sympathetic neurotransmitter(s). A survey of a large number of possible candidates for this neurotransmitter revealed that, in addition to cholinergic agonists, only a small group of peptides (all members of the secretin‐glucagon family) stimulated dopa synthesis in the SCG. The effective peptides included vasoactive intestinal peptide (VIP), peptide histidine isoleucine amide (PHI), and secretin. Consequently we looked for the presence of immunoreactivities for these three peptides in the SCG.VIP‐ and PHI‐like immunoreactive fibers were found in the SCG and in its major pre‐ and postganglionic nerve trunks. The distributions of the two immunoreactivities were very similar. Immunoreactive fibers were seen both singly and in bundles. In some instances, fibers were found apposed to neuronal cell bodies in the ganglion, and occasionally dense plexuses of fibers were found surrounding the neurons. In addition, punctate immunoreactive profiles were found apposed to the neurons in what appeared to be terminal fields. A small number of immunoreactive neuronal cell bodies were also seen in the ganglion. In a few instances, it was possible to establish, in serial sections, that the same cell body was immunostained with both VIP and PHI antisera. No secretin like‐immunoreactive fibers or cells were observed. The presence of VIP‐like and PHI‐like‐immunoreactive fibers in the cervical sympathetic trunk and in the SCG strengthens the possibility that these peptides, or a related molecule(s), serve as preganglionic neurotransmitters i

ISSN:0092-7317    

DOI:10.1002/cne.902800403

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractIn situhybridization with radiolabeled complementary RNA (cRNA) probes was used to determine the location of the messenger RNA (mRNA) encoding choline acetyltransferase (ChAT) inDrosophilanervous system. Areas in the cell‐rich cortical regions of the cerebrum and optic lobes hybridized with substantial concentrations of the probe. This contrasted with the cell‐sparse neuropil areas where no significant concentrations of probe were observed. Although most of the cortical regions were substantially labeled, there were regions within all of the areas where labeling was sparse or nonexistent. For example in the lamina, even though the monopolar cell layer appeared to be heavily labeled, there were some neuronal profiles that were not associated with the probe. Moreover, the epithelial glia that form an arch of cell profiles subjacent to the monopolar cells were not labeled, nor were amacrine neurons in the apex of the lamina near the external optic chiasma. The highest concentration of probe (∼140 grains/400 μm2) was observed in the laminar monopolar cell region and the cerebral cortical rind. The next most heavily labeled region (∼90 grains/400 μm2) occurred over cortical cells of the medulla‐lobula. In the peripheral nervous system, label over the antennal sensory neurons amounted to about 75 grains/400 μm2, and the retinular cell layer of the compound eye exhibited about 60 grains/400 μm2. The control probe did not hybridize in significant quantities in either cellular or noncellular regions. This study presents evidence that large numbers ofDrosophilacortical and primary sensory neurons contain the messenger RNA necessary for the production of ChAT, the acetylcholine‐synthesizing enzyme. Further, our findings provide baseline information for use in ontogenetic studies of cholinergic neurons inDrosophila, and they also provide normative data for studying the effects of mutant alleles at theChaorAceloci upon the transcription of ChA

ISSN:0092-7317    

DOI:10.1002/cne.902800404

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractTo investigate the structural changes in the hippocampal region (subiculum, Ammon's horn, and area dentata) associated with speciation, the volumes of homologous components of this region of the forebrain were compared in the two closely related murine rodent species,Apodemus flavicollis(yellow‐necked wood mice) andA. sylvaticus(long‐tailed field mice), and in two geographically separated groups ofA. sylvaticus.With the exception of the mossy fiber zone, no significant differences were found in the relative sizes of the components of Ammon's horn. Significant interspecific differences were found in the deep subiculum, in the intermediate (medial perforant path) and deep (commissural‐associational) zones of the molecular layer of the area dentata, and in the hilus. A significant intraspecific difference was found in the combined intermediate and superficial (medial and lateral perforant path) zone of the dentate molecular layer.Differences found in the relative size of the hilus and the mossy fiber zone of Ammon's horn were complementary in that the combined volumes of these zones, which are both terminal fields of dentate granule cells, did not differ in the two species. This finding provides evidence that the distribution of the terminal field of a projection system can be altered while the size of the terminal field is maintained.Within the hippocampal region, components of Ammon's horn appear well suited for quantitative comparative studies that span taxonomic units beyond the species level. In agreement with previous quantitative studies, differences in the volumes of components of Ammon's horn found in species of different orders are more likely to reflect phylogenetic trends rather than changes resulting from specializations of the particular species used. This is not true for the subiculum and the components of the area dentata.Experimentally induced changes in the connectivity of the hippocampal region are discussed in terms of the structural changes which may be responsible for the quantitative differences observed between the two species studied

ISSN:0092-7317    

DOI:10.1002/cne.902800405

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractSingle auditory nerve fibers of type I spiral ganglion cells in cats were electrophysiologically characterized by recording with micropipettes inserted into the axon and then labeled by intracellular injections of horseradish peroxidase (HRP) through the same pipettes. This method for staining and studying single neurons allowed us to describe structure‐function relationships for labeled endbulbs of Held and the somata of their postsynaptic spherical bushy cells. The silhouette areas of terminal endbulbs and the corresponding somata of spherical bushy cells were determined by planimetry from drawings made with a light microscope and drawing tube. On the presynaptic side, endbulb area is related to fiber characteristic frequency (CF, the frequency to which a fiber is most sensitive) such that the largest endbulbs arise from fibers having CFs between 1 and 4 kHz; smaller endbulbs can arise from fibers of any CF. Endbulb area is not correlated with fiber spontaneous discharge rate (SR). Dividing the endbulb's silhouette area by its silhouette perimeter, however, yields a “form factor” that is a reliable indicator of fiber SR: Endbulbs from fibers of low‐medium SR (≤18 spikes/second) have form factor values less than 0.52, whereas endbulbs of high SR fibers (>18 spikes/second) have values greater than 0.52. This form factor should therefore be predictive of SR groupings in auditory fibers for which physiological data are not available.On the postsynaptic side, the somata of spherical bushy cells receiving endbulbs from low‐medium SR fibers are on average smaller than those receiving endbulbs from high SR fibers. In contrast, the nuclei of the spherical bushy cells are the same size regardless of presynaptic fiber SR. Some of the effects of low‐medium SR fibers on their postsynaptic targets, when compared to those of high SR fibers, appear to be mimicked by effects of experimentally induce

ISSN:0092-7317    

DOI:10.1002/cne.902800406

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe neural organization of the pig masseter, an architecturally and functionally compartmentalized muscle, was investigated by using dissection, glycogen depletion, evoked electromyography, and counts of axon numbers at various levels along the masseteric nerve. The masseteric nerve enters the muscle as two rostral branches, which also supply the zygomatico‐mandibularis, and a more caudal main branch, which soon divides into four terminal nerves with variable distributions. Stimulation of filaments containing roughly 50 extrafusal motor axons resulted in glycogen depletion of 5–20% of the muscle fibers in very small subvolumes of the masseter; the affected subvolumes were delimited by perimysium. Electromyography after stimulation of various branches of the nerve confirmed the distributions deduced from anatomy and further indicated that axons do not branch between the rostral and main nerve branches but may occasionally do so among the more distal terminal branches of the main branch. The proximal trunk of the masseteric nerve contains about 3,500 myelinated fibers with a bimodal size distribution. Approximately 1,000 of the larger fibers were estimated to be extrafusal motor axons. Along the proximal trunk of the nerve, fibers were constantly rearranged; coupled with the observation that the locations of motor unit territories were usually not related to the position of the stimulated axons within the nerve, this suggests that the nerve trunk is not strictly ordered somatotopica

ISSN:0092-7317    

DOI:10.1002/cne.902800407

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe distribution of neuropeptidelike immunoreactivities in the adult guinea pig olfactory bulb was studied immunohistochemically with antiseraraised against neurotensin (NT), substance P (SP), methionine‐enkephalin‐Arg6‐Gly7‐Leu8(ENK), somatostatin (SOM), neuropeptide Y (NPY), and cholecystokinin‐8 (CCK).In the main olfactory bulb, NT‐like immunoreactive (NT‐IR) neurons were found among periglomerular cells. In addition, a few periglomerular cells showed ENK‐like immunoreactivity. Granule cells displaying SP‐ or ENK‐like immunoreactivities and short axon cells with SOM‐ or NPY‐like immunoreactivities were observed in the deeper half of the granule cell layer. SOM‐IR short axon cells were also seen in the external plexiform layer. Dense NT‐ or NPY‐IR fibers were distributed in superficial lamina of the granule cell layer, and sparse SP‐ or CCK‐IR fibers were found in the glomerular layer.In the accessory olfactory bulb, some mitral, periglomerular, and granule cells showed NT‐like immunoreactivity. SP‐ or ENK‐IR granule cells were also observed.These results are discussed in relation to laminar organization of the olfactory bulb. The most characteristic features of peptide distribution in guinea pigs, as compared with that of rats in previous studies, were the relative abundance of NT‐IR structures and the lack of SP‐

ISSN:0092-7317    

DOI:10.1002/cne.902800408

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe cytoarchitecture of the bed nuclei of the stria terminalis (BST) in the adult male rat was examined in the three standard planes of section, and the results were compared with the distribution of immunohistochemical staining for a variety of neuropeptides in a companion paper (Ju et al.:J. Comp. Neurol. 280:603–621, '89). It is clear that the BST is an extremely complex mass of gray matter that can be parcellated most clearly into anterior and posterior divisions, which are separated by a more‐or‐less vertical septum of fibers associated with the stria terminalis. The anterior division can be further parcellated into dorsal, lateral, and ventral areas, and each of these areas, along with the posterior division, can be thought of as containing more‐or‐less discrete nuclei embedded within a relatively undifferentiated region. Thus, we have recognized a central core in the anterodorsal area; oval, juxtacapsular, and rhomboid nuclei in the anterolateral area; and fusiform, dorsomedial, dorsolateral, magnocellular, and ventral nuclei in the anteroventral area. The most obvious cell groups in the posterior division include the principal, interfascicular, transverse, premedullary, and dorsal nuclei. Problems associated with defining the limits of the BST, and with comparing our results with the earlier literature, are

ISSN:0092-7317    

DOI:10.1002/cne.902800409

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractIn a companion paper (Ju and Swanson;J. Comp. Neurol. 280:587–602, '89) we described a parcellation scheme for the bed nuclei of the stria terminalis (BST) that was based on cytoarchitectonic criteria. In the work reported here, antisera to the neuropeptides corticotropin‐releasing hormone, neurotensin, galanin, substance P, and cholecystokinin were used to determine the extent to which immunostained neuronal cell bodies and presumed terminal fields are correlated with this cytoarchitectonic scheme in the adult male rat. The results confirm the validity of the cytoarchitectonic parcellation and provide additional chemoarchitectonic criteria for determining the (as yet still somewhat arbitrarily defined) border between the BST and the ventrally adjacent preoptic region, for distinguishing between the anterior and posterior divisions of the BST, and for identifying and distinguishing between the particular cell groups or nuclei within each division. The projections of each neuropeptide‐containing cell group in various parts of the BST remain to be determined, as do the precise origins of the localized immunoreactive terminal fields identified

ISSN:0092-7317    

DOI:10.1002/cne.902800410

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractAdult male rats have substantially more motoneurons than do females in two motor nuclei in the lumbar spinal cord: the spinal nucleus of the bulbocavernosus (SNB) and the dorsolateral nucleus (DLN). Previous studies of the development of the SNB revealed that the sex difference in SNB motoneuron number is established through a differential motoneuron death which is under the control of androgens. In this study the development of the sexually dimorphic DLN was examined to test the hypothesis that early androgen action also determines the sex difference in DLN motoneuron number by regulating normally occurring motoneuron death. Because SNB motoneurons may migrate from the DLN, quantitative examination of DLN development was necessary in order to understand more completely the cellular mechanisms contributing to the establishment of dimorphic motoneuron number.At 5 days before birth, the number of motoneurons in the DLN is significantly higher than in adulthood in both sexes, and no sex difference is present. There is a decrease in motoneuron numbers prenatally in both sexes, which is consistent with the emigration of presumptive SNB motoneurons. Motoneuron number declines differentially through the first week of postnatal life and by postnatal day 10 motoneuron numbers are in the adult range and the sex difference is fully expressed. Females lose significantly more DLN motoneurons than males through a differential death as revealed by the higher incidence of degenerating cell profiles. Females treated with testosterone propionate have a male‐typical motoneuron loss and incidence of degenerating cells. These results indicate that steroid hormones establish the sex difference in DLN motoneuron number by regulating normally occurring cell deat

ISSN:0092-7317    

DOI:10.1002/cne.902800411

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY