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  • 1
    Electronic Resource
    Electronic Resource
    Synergism between 5-HT1B/1D and 5-HT1A receptor antagonists on turnover and release of 5-HT in guinea-pig brain in vivo (1999)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 359 (1999), S. 110-116 
    Details
    ISSN: 1432-1912
    Keywords: Key words 5-HT1B and 5-HT1A receptors ; 5-HT turnover ; 5-HT release ; Guinea pigs ; GR 127935 ; WAY-100635 ; Microdialysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects on 5-HT turnover (5-HIAA/5-HT ratio) and extracellular 5-HT and 5-HIAA levels (in vivo microdialysis in freely moving animals) were analysed in guinea-pig brains following the 5-HT1B receptor antagonist, GR 127935 {N-[4-methoxy-3-(4-methyl-1-piperazinyl)phenyl]-2’-methyl-4’-(5-methyl-1,2,4-oxadiazol-3-yl) [1,1-biphenyl]-4-carboxamide}, or the 5-HT1A receptor antagonist, WAY-100635 (N-{2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl}-N-(2-pyridinyl) cyclohexanecarboxamide trihydrochloride), administered alone or in combination. GR 127935, injected alone, increased 5-HT turnover with maximal effects approximately 50% above the control levels in the four brain regions examined (hypothalamus, hippocampus, striatum and frontal cortex). GR 127935 significantly increased extracellular concentrations of 5-HT and 5-HIAA in frontal cortex (40%), whereas 5-HIAA, but not 5-HT, was elevated in striatum (20–30%). WAY-100635 did not significantly change 5-HT turnover but caused a small significant increase in the extracellular 5-HT and 5-HIAA concentrations in both striatum and frontal cortex. The combined treatment with GR 127935 and WAY-100635 resulted in an increased 5-HT turnover reaching maximal effects of 70–90% above the control values in all brain regions tested and produced a significant elevation of striatal and frontal cortex extracellular 5-HT (40% and 60%, respectively) and 5-HIAA (60% and 70%, respectively) concentrations. The synergistic effect of the two receptor antagonists on the 5-HT turnover and the terminal release of 5-HT indicate somatodendritic 5-HT release and stimulation of inhibitory 5-HT1A receptors at this level. Extracellular 5-HIAA seems to be a better marker than 5-HT itself for the evoked 5-HT release when the reuptake mechanism is intact.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00005329
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  • 2
    Electronic Resource
    Electronic Resource
    Male cytoplasmic diminution and male germ unit in young and mature pollen of Cymbidium goeringii: a 3-dimensional and quantitative study (1992)
    Springer
    Sexual plant reproduction 5 (1992), S. 169-181 
    Details
    ISSN: 1432-2145
    Keywords: Cymbidium goeringii ; Cytoplasmic diminution ; Generative cell ; Male germ unit ; Vegetative nucleus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Pollinia of Cymbidium goeringii (Orchidaceae) were examined at a young stage (approx. 2 weeks before anthesis) and at anthesis using transmission electron microscopy, computer-assisted serial reconstruction and quantitative cytology. At the young stage, the generative cell (GC) has a spherically shaped main body with a large nucleus and 1 to 4 cytoplasmic extensions (up to 10 μm long) physically associated with a groove on one side of the vegetative nucleus (VN). By anthesis, some GCs lose their cytoplasmic extensions, becoming spherical. The GC surface becomes highly wrinkled, the distance between the GC and the VN increases and the two may separate completely. Enucleated cytoplasmic bodies (ECBs) are apparently generated by the GC, as evidenced by their similar ultrastructural appearance and distribution near the GC. ECBs are likely produced from two sites: the GC surface and the tips of cytoplasmic extensions of the GC. Vesicle-containing bodies (VCBs) may be generated from the lateral surface of the GC and may also represent a degeneration stage of ECBs, finally fusing with lipid bodies. Heritable organelles are rare and usually absent in the GC of Cymbidium: 0.176 mitochondria and 0.0042 plastids per GC were observed at the young stage and no mitochondria and 0.019 plastids at anthesis. Of 16 cellular parameters examined during GC development, all decreased with the exception of the surface area and volume of ECBs/ VCBs (which remained stable) and GC vacuoles (which increased). Significant decreases in 11 parameters presumably relate to dehydration of the pollen and male cytoplasmic diminution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00189808
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Sperm cells in pollen tubes ofNicotians tabacum L.: three-dimensional reconstruction, cytoplasmic diminution, and quantitative cytology (1992)
    Springer
    Protoplasma 168 (1992), S. 172-183 
    Details
    ISSN: 1615-6102
    Keywords: Cytoplasmic inheritance ; Male cytoplasmic diminution ; Male gamete (angiosperm) ; Male germ unit ; Nicotiana ; Tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The organization of the sperm cells and vegetative nucleus (male germ unit) ofNicotiana tabacum was examined 18 h after semivivo pollination using transmission electron microscopy, computerassisted serial section reconstruction and quantitative cytology. Based on a measurement of 11 cellular parameters in nine reconstructed sperm cell pairs, there are no statistically significant differences between the two cells. The Svn is characterized by a strapshaped cytoplasmic extension that is physically associated with the surface of the vegetative nucleus. The nucleus is located adjacent to the sperm crosswall, with sperm organelles being distributed between the nucleus and the extension. The Sua is a tapered cell with cytoplasmic areas at both poles and deep axial invaginations near the crosswall. This cell has a centrally-located nucleus and a largely polar distribution of organelles. Three mechanisms for cytoplasmic diminution were observed that appear to contribute actively to the loss of cytoplasmic volume and organelles: (1) enucleated cytoplasmic body production in the Sua; (2) vesiculation at the tip of the cytoplasmic projection of the Svn; and (3) vesicle-containing body accumulation in the periplasm of both the Svn and Sua.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01666263
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    Paper (German National Licenses)
    Fulltext
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