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  • 1
    Electronic Resource
    Electronic Resource
    Few cortical cholecystokinin immunoreactive neurons have long projections (1985)
    Springer
    Experimental brain research 59 (1985), S. 533-542 
    Details
    ISSN: 1432-1106
    Keywords: Cholecystokinin ; Immunocytochemistry ; Neuropeptides ; Cerebral cortex ; Local circuit neurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cholecystokinin (CCK)-like immunoreactive neurons have been reported to be widely distributed throughout both the neo- and allocortices. In the present study, we were interested in determining whether these cortical CCK neurons have long projections using the double-labeling technique of fluorescence retrograde tracing combined with immunofluorescence for CCK. The distribution of CCK immunoreactive perikarya and fibers was plotted throughout the rostro-caudal extent of the cerebral cortex in both untreated and colchicine-treated albino rats. In the double-labeling experiments, the animals received injections of fluorescent retrograde tracers into cortical, limbic, striatal or thalamic structures, followed one to two days later by colchicine treatment. Brains were subsequently processed for indirect immunofluorescence for CCK-octapeptide and fluorescent dye localization. It was found that 1) a small number of prefrontal cortical CCK neurons were double-labeled with both fluorescent dye and immunofluorescence for CCK after dye injection into midline thalamus, 2) only rarely were cortical CCK neurons double-labeled with injection of tracers into cortex, striatum, or other subcortical structures, 3) numerous midbrain CCK neurons were double-labeled after dye injection into prefrontal cortex and anterior cingulate cortex. and 4) colchicine or cannula injection damage to cortical forebrain tracts (corpus callosum, internal capsule, external capsule, anterior commissure) resulted in the appearance of numerous CCK immunoreactive fibers not normally seen in the undamaged tracts. Although the possibility remains that cortical CCK neurons may be refractory to transport of retrograde tracers, these results suggest that CCK-like immunoreactive neurons of the rat cerebral cortex are predominantly local circuit neurons and that only minor corticocortical and cortico-subcortical CCK-containing projections exist.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00261344
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  • 2
    Electronic Resource
    Electronic Resource
    Neurotensin and cholecystokinin coexistence within neurons of the ventral mesencephalon: projections to forebrain (1987)
    Springer
    Experimental brain research 68 (1987), S. 277-289 
    Details
    ISSN: 1432-1106
    Keywords: Neurotensin ; Cholecystokinin ; Colocalization ; Mesotelencephalic system ; Ventral tegmental area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The colocalization of neurotensin- and cholecystokinin-like immunoreactivities was demonstrated in neurons of the ventral mesencephalon of the rat by using a double-labeling indirect immunofluorescence procedure for the simultaneous detection of two antigens in the same tissue section. Greater than 90% of the neurotensin-positive perikarya distributed throughout the ventral mid-brain (primarily located in the ventral tegmental area, medial substantia nigra, and rostral and caudal linear raphe nuclei) were found to also contain cholecystokinin immunoreactivity. Neurons single-labeled for either peptide were also present, with those immunoreactive for cholecystokinin alone far outnumbering those containing only neurotensin. By combining the double-labeling colocalization technique with fluorescence retrograde tracing, some of the forebrain projections of these neurons were determined. Ventral mesencephalic neurons containing both neurotensin and cholecystokinin were found to project to the nucleus accumbens, prefrontal cortex, or amygdala. The present results, combined with those of previous studies, suggest that there are complex heterogeneous subpopulations of presumed dopaminergic ventral mesencephalic neurons which give rise to the ascending mesotelencephalic systems and which may contain both neurotensin and cholecystokinin, either peptide alone, or neither of these two peptides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248793
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  • 3
    Electronic Resource
    Electronic Resource
    GABAergic neurons comprise a major cell type in rodent visual relay nuclei: an immunocytochemical study of pretectal and accessory optic nuclei (1985)
    Springer
    Experimental brain research 61 (1985), S. 194-203 
    Details
    ISSN: 1432-1106
    Keywords: GABAergic neurons ; Accessory optic nuclei ; Pretectal nuclei ; Gerbil ; Rat ; Visual system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The enzyme glutamic acid decarboxylase (GAD) has been localized in sections of rodent brains (gerbil, rat) using conventional immunocytochemical techniques. Our findings demonstrate that large numbers of GAD-positive neurons and axon terminals (puncta) are present in the visual relay nuclei of the pretectum and the accessory optic system. The areas of highest density of these neurons are in the nucleus of the optic tract (NOT) of the pretectum, the dorsal and lateral terminal accessory optic nuclei (DTN, LTN), the ventral and dorsal subdivisions of the medial terminal accessory optic nucleus (MTNv, MTNd), and the interstitial nucleus of the posterior fibers of the superior fasciculus (inSFp). The findings indicate that 27% of the NOT neurons are GAD-positive and that these neurons are distributed over all of the NOT except the most superficial portion of the NOT caudally. The GAD-positive neurons of the NOT are statistically smaller (65.9 μm2) than the total population of neurons of the NOT (84.3 [j,m2) but are otherwise indistinguishable in shape from the total neuron population. The other visual relay nuclei that have been analyzed (DTN, LTN, MTNv, MTNd, inSFp) are similar in that from 21% to 31% of their neurons are GAD-positive; these neurons are smaller in diameter and are more spherical than the total populations of neurons. The data further show that a large proportion of the neurons in these visual relay nuclei are contacted by GAD-positive axon terminals. It is estimated that approximately one-half of the neurons of the NOT and the terminal accessory optic nuclei receive a strong GABAergic input and have been called “GAD-recipient neurons”. Further, the morphology of the GAD-positive neurons combined with their similar distribution to the GAD-recipient neurons suggest that many of these neurons are acting as GABAergic, local circuit neurons. On the other hand, the large number of GAD-positive neurons in the NOT and MTN (20–30%) in relation to estimates of projection neurons (75%) presents the possibility that some may in fact be projection neurons. The overall findings provide morphological evidence which supports the general conclusion that GABAergic neurons play a significant role in modulating the output of the visually related NOT and terminal accessory optic nuclei.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235635
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  • 4
    Electronic Resource
    Electronic Resource
    Neurons containing retrogradely transported Fluoro-Gold exhibit a variety of lysosomal profiles: A combined brightfield, fluorescence, and electron microscopic study (1989)
    Springer
    Journal of neurocytology 18 (1989), S. 333-343 
    Details
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The advantages of axonally transported Fluoro-Gold as a retrograde fluorescent marker are numerous. The objective of the present study was to determine whether transported Fluoro-Gold is visible in either semi-thin sections for light microscopy or thin sections for electron microscopy. Rats received injections of Fluoro-Gold into either the striatum or thoracic spinal cord. After appropriate survival times, labelled neurons were observed with the fluorescence microscope in brain regions that are known to project to the injected areas. Sections that contained labelled cells were embedded in plastic and examined with a fluorescence microscope. Semi-thin sections of unosmicated tissue displayed high-resolution fluorescent labelling of somata and dendrites. In contrast, osmicated tissue did not fluoresce, but numerous dark granules were observed in the dendritic and perikaryal cytoplasm of labelled neurons in toluidine blue stained sections that were examined with brightfield optics. The unosmicated tissue did not display these granules, and this finding suggested that the granules are composed of membranes. Neurons in other brain regions that are known not to project to the injection sites did not contain these dark granules. Adjacent thin sections examined with the electron microscope displayed numerous electron-dense, lysosome-like organelles in the cytoplasm of labelled neurons. The electron density of these organelles was greater than that of lysosomes in unlabelled neurons. Three types of distinctive organelles were observed in these preparations: (1) relatively dense concentric lamellar bodies of various sizes; (2) heterogeneous or lipofuscin-like lysosomes; and (3) coarse grained lysosomes. Control sections and unlabelled neurons did not display these organelles. Therefore, these organelles appear to correlate with Fluoro-Gold localized within the somata and dendrites of retrogradely labelled neurons. It is not known if they are the Fluoro-Gold itself, or represent a physiological effect on membranes. The results of this study indicate that Fluoro-Gold may be useful for tract tracing at the electron microscopic level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01190836
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    Paper (German National Licenses)
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