摘要:

AbstractElectron microscopic immunocytochemistry was employed to examine the ultrastructure of luteinizing hormone‐releasing hormone (LHRH) neurons and their projections to the median eminence in the sheep brain. LHRH perikarya in the preoptic area of anestrous ewes are less innervated than nonimmunoreactive cells in the same sections, but still receive numerous synaptic inputs, primarily onto distal dendrites and small somatic protuberances. Axon terminals synapsing upon LHRH cells contain a combination of clear spherical vesicles and larger dense‐core vesicles. Interestingly, LHRH cell bodies and dendrites are almost entirely surrounded by glial processes. These processes intervene between immunoreactive elements that at a light microscopic level appear to be in contact with each other. Thus no evidence was obtained at the ultrastructural level for contacts among adjacent LHRH cells or dendrites in the preoptic area. Synaptic inputs onto LHRH cell bodies and dendrites appear to penetrate this glial sheath. In contrast to the absence of contacts among LHRH cells in the preoptic area, individual LHRH terminals in the median eminence are often clustered in direct plasma membrane contact. Comparisons between animals of differing reproductive status are needed to determine whether alterations in synaptic inputs, glial ensheathment, or LHRH‐LHRH appositions, may underlie seasonal changes in the activity of LHRH ne

ISSN:0092-7317    

DOI:10.1002/cne.902730402

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis report examines the generation of cholinergic neurons in the spinal cord in order to determine whether the transmitter phenotype of neurons is associated with specific patterns of neurogenesis. Previous immunocytochemical studies identified four groups of choline acetyltransferase (ChAT)‐positive neurons in the cervical enlargement of the rat spinal cord. These cell groups vary in both somatic size and location along the previously described ventrodorsal neurogenic gradient of the spinal cord. Thus, large (and small) motoneurons are located in the ventral horn, medium‐sized partition cells are found in the intermediate gray matter, small central canal cluster cells are situated within lamina X, and small dorsal horn neurons are scattered predominantly through laminae III‐V. The relationships among the birthdays of these four subsets of cholinergic neurons have been examined by combining3H‐thymidine autoradiography and ChAT immunocytochemistry.Embryonic day 11 was the earliest time that neurons were generated within the cervical enlargement. Large and small ChAT‐positive motoneurons were produced on E11 and 12, with 70% of both groups being born on E11. ChAT‐positive partition cells were produced between E11 and 13, with their peak generation occurring on E12. Approximately 70% of the cholinergic central canal cluster and dorsal horn cells were born on E13, and the remainder of each of these groups was generated on E14.Other investigators have shown thatall neuronswithin the rat cervical spinal cord are produced in a ventrodorsal sequence between E11 and E16. In contrast,ChAT‐positive neuronsare born only from E11 to E14 and are among the earliest cells generated in the ventral, intermediate, and dorsal subdivisions of the spinal cord. However, all cholinergic neurons are not generated simultaneously; rather their birthdays are correlated with their positions along the ventrodorsal gradient of neurogenesis. The fact that large motoneurons and medium‐sized partition cells are born before small central canal cluster and dorsal horn cells would appear to support the generalization that large neurons are generated before small ones. However, the location of spinal cholinergic neurons within the neurogenic gradient seems to be more importantly associated with the time of cell generation than somal size. For example, when large and small motoneurons located at the same dorsoventral spinal level are compared, both sizes of cells are generated at the same time and in similar proportions. In summary, the present results suggest that information associated with a cell's position within the neurogenic gradient is a more potent determinant of neuronal birthdays than somal size or transm

ISSN:0092-7317    

DOI:10.1002/cne.902730403

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

年代:1988

数据来源: WILEY

摘要:

AbstractAutoradiography following3H‐glycine (Gly) uptake and immunocytochemistry with a Gly‐specific antiserum were used to identify neurons inMacacamonkey retina that contain a high level of this neurotransmitter. High‐affinity uptake of Gly was shown to be sodium dependent whereas release of both endogenous and accumulated Gly was calcium dependent. Neurons labeling for Gly included 40‐46% of the amacrine cells and nearly 40% of the bipolars. Synaptic labeling was seen throughout the inner plexiform layer (IPL) but with a preferential distribution in the inner half. Bands of labeled puncta occurred in S2, S4, and S5.Both light and postembedding electron microscopic (EM) immunocytochemistry identified different types of amacrine and bipolar cell bodies and their synaptic terminals. The most heavily labeled Gly+cell bodies typically were amacrine cells having a single, thick, basal dendrite extending deep into the IPL and, at the EM level, electron‐dense cytoplasm and prominent nuclear infoldings. This cell type may be homologous with the Gly2 cell in human retina (Marc and Liu:J. Comp. Neurol. 232:241‐260, ′85) and the AII/ Gly2 of cat retina (Famiglietti and Kolb:Brain Res. 84:293‐300, ′75; Pourcho and Goebel:J. Comp. Neurol. 233:473‐480, ′85a). Gly+amacrines synapse most frequently onto Gly−amacrines and both Gly−and Gly+bipolars. Gly+bipolar cells appeared to be cone bipolars because their labeled dendrites could be traced only to cone pedicles. The pattern of these labeled dendritic trees indicated that both diffuse and midget types of bipolars were Gly+. The EM distribution of labeled synapses showed Gly+amacrine synapses throughout the IPL, but these composed only 11‐23% of the amacrine population. Most of the Gly+bipolar terminals were in the inner IPL, where 70% of all bipolar terminals were labeled. These findings are consistent with previous data from cats and humans and suggest that both amacrine and bipolar cells contribute to glycine‐mediated neurotran

ISSN:0092-7317    

DOI:10.1002/cne.902730404

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe AChE fiber distribution within the human hippocampus and parahippocampal gyrus was studied in order to provide normative data for the examination of cholinergic fiberarchitecture in human pathology and to clarify the cytoarchitectonic organization of these structures. A modification of the Koelle method was used to stain temporal lobe serial sections from 6 neurologically normal human brains collected at autopsy.The hippocampal formation contains some of the densest staining of any cortical area. Regions with the heaviest concentrations of AChE fibers include a thin band along the inner edge of the molecular layer of the dentate gyrus (ml‐DG) and parts of the CA2, CA3, and CA4 sectors of Ammon's horn. Staining is of intermediate intensity in the CA1 region. The subiculum (S) is more lightly stained than the CA fields. Staining in the parahippocampal gyrus is generally less dense than in the hippocampal formation. The most conspicuous feature of the human entorhinal cortex (EC) is the AChE‐rich fiber patches seen overlapping the stellate cell islands in layer II. An additional band of relatively dense AChE staining is identified in layers IV‐V. Prominent AChE‐rich polymorphic neurons are present within the hilum of the dentate gyrus.The CA1/subiculum transition in Nissl preparation is characterized by an oblique interdigitation of CA1 cells. The transition from EC to prorhinal cortex occurs along the medial bank of the rhinal sulcus and is characterized by a band of AChE staining, which slopes obliquely away from layer II until it joins an intermediate pyramidal cell layer. Some comparisons with AChE staining in the monkey were made. The monkey has a similar pattern except in DG, where the intensely AChE staining band along the inner ml‐DG is thicker and much more prominent. In comparison to the human, the monkey has more conspicuous AChE staining in the parasubicul

ISSN:0092-7317    

DOI:10.1002/cne.902730405

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

年代:1988

数据来源: WILEY

摘要:

AbstractWe reported a development of murine monoclonal antibodies to a molluscan small cardioactive peptide (SCPB) and their application to immunolabeling of neurons in several molluscan and arthropod species. In vitro stimulations of mouse lymphocytes with SCPBconjugated to a carrier protein yielded exclusively IgM class antibodies; in vivo stimulation resulted in generation of both IgM and IgG classes of antibodies. Monoclonal antibodies of the IgM class labeled identified SCP‐containing neuron B11 in the frozen sections of the buccal ganglia ofTritonia diomedia.These antibodies failed to stain any neurons in whole mount preparations. A monoclonal antibody of IgG1 subclass selectively labeled neurons in both frozen sections and whole mount preparations of diverse invertebrate species. Thus, neurons B11, B12, and GE1 and several other neurons of the buccal and gastroesophageal ganglia ofT. diomediabound the antibody, and a similar pattern of immunolabeling was found in the closely related gastropodTritonia festiva.We also observed SCPB‐like immunoreactivity in the central neurons of other nudibranch and pulmonate molluscs and in examples of insect (Acheta domesticusandThermobia domestica) and crustacean (Semibalanus cariosus) classes of the Arthropoda. Our results suggest a specific pattern of distribution of SCPB‐like immunoreactivity in the gastropod nervous system and a broad occurrence of SCPB‐like antigenicity in the diverse invert

ISSN:0092-7317    

DOI:10.1002/cne.902730406

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

年代:1988

数据来源: WILEY

摘要:

AbstractGlutamate decarboxylase (GAD) immunohistochemistry was employed at the light and electron microscopic levels to localize GABAergic structures in the basolateral amygdaloid nucleus (BL).The GAD‐immunoreactive (GAD‐IR) staining pattern consisted of punctate structures and a morphologically diverse group of GAD‐IR neurons. At the electron microscopic level many of these punctate structures were found to make symmetrical synaptic contacts with cell bodies as well as distal parts of unlabeled, presumably projection and nonprojection, neurons. In addition, GAD‐immunoreactive neurons were identified in the BL, and they had the ultrastructural characteristics of local circuit or intrinsic neurons and were not retrogradely labeled with HRP following ventral striatal injections. Some of these GAD‐immunoreactive neurons were contacted by GABAergic boutons, forming symmetrical synaptic contacts.GABAergic innervation of amygdaloid projection neurons in the BL was identified by combining GAD immunohistochemistry with Golgi impregnation and retrograde tracing of horseradish peroxidase (HRP) following injections of the tracer in the olfactory‐tubercle‐related parts of the ventral striatum. Amygdalostriatal projection neurons in the BL were observed to be in continuity with neurons in the piriform cortex which project to the ventral striatum. The results provide direct evidence for the presence of GAD‐IR boutons in the BL making synaptic contacts with identified amygdalostriatal projection neurons.The present study provides direct anatomical evidence for the physiological observation that GABA exhibits a powerful regulation of the amygdaloid projection neurons in the BL and lends further support to the concept of a corticallike functional organization of the basol

ISSN:0092-7317    

DOI:10.1002/cne.902730407

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

年代:1988

数据来源: WILEY

摘要:

AbstractPrevious experiments in cats have shown that complete contralateral visual neglect is produced by removing all known visual cortex on one side of the brain, which can then be reversed by damaging the opposite superior colliculus. Presumably, descending facilitatory influences from the visual cortex to the ipsilateral superior colliculus are counterbalanced by intercollicular inhibition (Sprague:Science 153:1544‐1546, ′66). However, not all of visual cortex or all of the superior colliculus needs to be involved in this circuit. It is the deep rather than the superficial laminae of the superior colliculus that are primarily involved in visual attentive and orientation behaviors, and these laminae are largely independent of primary visual cortex. However, they do depend on corticotectal influences from a comparatively small extraprimary visual area of the posterior region of the lateral suprasylvian cortex (PSSC—Ogasawara et al:J. Neurophysiol. 52:1226‐1245, ′84). The present experiments demonstrate that lesions only a few millimeters in diameter in this corticotectal zone of the PSSC can produce profound visual neglect. While damage to this area has little, if any, effect on superficial laminae visual activity, it produces a dramatic decrease in the visual activity of the deep laminae. These cats with PSSC lesions fail to orient to a visual stimulus that is introduced suddenly into the contralateral visual field, yet they respond on nearly 100% of the trials to this same stimulus when it is presented in the ipsilateral visual field. The lesion‐induced visual neglect produced by PSSC lesions is long‐lasting but can be abruptly ameliorated by a midbrain lesion that primarily involves, or undercuts, the deep laminae of the contralateral superior colliculus. Thus, (1) visual neglect can be produced by depriving the deep laminae of the superior colliculus of visual inputs from the cortex, even when the principal visual cortical regions (17, 18, and 19) and their target structures are intact, and (2) visually guided behavior can be restored by eliminating afferents originating in, or passing through, the deep laminae of the contralateral superi

ISSN:0092-7317    

DOI:10.1002/cne.902730408

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis study summarizes the findings from postmortem examination of the brains of 22 control cases without neurological deficit, 12 cases of senile dementia of the Alzheimer type (SDAT), and nine cases of Parkinson's disease (three without signs of intellectual deterioration, four with dementia, and two atypical with dementia nonresponsive to L‐dopa treatment). The aim of this study was to find the similarities and differences in galanin innervation of the cholinergic basal nucleus neurons in these dementing disorders as compared with controls. Immunocytochemistry with antibodies against galanin peptide and against choline acetyltransferase was applied on perfused brain preparations. Galanin peptide is present in the basal nucleus of Meynert neuron networks in the normal human brain: in local circuit neurons, in a number of galanin/cholinergic neurons, and in a feedback circuit (via collaterals) that terminate upon the cholinergic neuronal somata and dendrites. Thus, peptide galanin circuits could function as powerful modulators of the activities of basal nucleus cholinergic neurons, both within the basal forebrain and in their wider projections to the neocortex and amygdala. As galanin has been shown to inhibit cholinergic activity, this galanin network could suppress the activity of cholinergic neurons. In SDAT, there is a primary loss of cholinergic neurons compounded by a secondary reaction of the remaining cholinergic neurons to the terminal degeneration in the cortex. Galanin networks demonstrate an inverse relationship to the cholinergic cell loss. Galanin axons hypertrophy and hyperinnervate the remaining cholinergic neurons. In Parkinson's disease the loss of cholinergic neurons is accentuated by the presence of dementia: the hypertrophy of the galanin axonal networks on cholinergic neurons is dramatic in Parkinson's disease with dementia.These observations throw new light on the neurotransmitter bases for these dementias. Galanin controls cholinergic mechanisms in the basal nucleus of Meynert, and dementia is accompanied by augmentation of galanin innervation onto an already depressed population of cholinergic neurons, thus demonstrating an appreciable amount of plasticity even in aged brain. These findings suggest that the present therapy of cholinergic enhancement as a means to retard intellectual deterioration can by itself have little effect at best, in these dementias. The suppressive effect of galanin peptide has to be reduced or curtailed, perhaps concurrently with the treatment of the cholinergic deficit. It is suggested that the curtailment of galanin activity might be achieved by galanin peptide antagonists or by small organic compounds that react with the galanin receptor and that these may constitute new therapeutic approaches toward dementi

ISSN:0092-7317    

DOI:10.1002/cne.902730409

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

年代:1988

数据来源: WILEY

摘要:

AbstractIndividual neurons containing prosomatostatin mRNA were identified with in situ hybridization histochemistry. Our results demonstrate a widespread distribution of prosomatostatin mRNA in several regions of the rat central nervous system. Neurons containing this transcript were most abundant in the anterior olfactory nucleus, hypothalamus, hippocampus, and amygdala as well as in all regions of the cerebral cortex. Moreover, the distribution of mRNA‐containing perikarya was coextensive with the location of neurons containing somatostatin‐like immunoreactivity in all areas of the brain examined. Somatostatin neurons varied in their morphology and amount of hybridization signal from region to region. The widespread distribution and regional variations in neuronal morphology and the amount of hybridization signal are consistent with a neurotransmitter and/or a neuromodulator role for somatostatin in addition to its well‐established neuroendocrine role. These results demonstrate that both the peptide and its mRNA are found in perikarya in the same areas and that they are therefore the sites of synthesis for somatos

ISSN:0092-7317    

DOI:10.1002/cne.902730410

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to determine the location of neuronal cell bodies with projections to the cervical or lumbar spinal cord in the adult duck and goose. Bilateral or unilateral injections (5‐10 μl) of the retrograde tracer dye True Blue (TB:5%) were made into the high cervical or high lumbar levels of the spinal cord. Similar results were obtained in both species. First, we found no evidence of retrogradely labelled cells in the telencephalon. In the brainstem, the distribution of TB cells was similar to those previously reported for the pigeon; however, the present study now demonstrates that some of these descending pathways project as far as the lumbar cord. We also discovered that there is a topographical representation of spinal projecting neurons within the avian medullary‐pontine reticular forma

ISSN:0092-7317    

DOI:10.1002/cne.902730411

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

年代:1988

数据来源: WILEY