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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 306 (1979), S. 173-177 
    ISSN: 1432-1912
    Schlagwort(e): Serotonin turnover ; Kainic acid ; Corpus striatum ; Feedback regulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Kainic acid, a cyclic analog of glutamate, has been reported by other investigators to reduce the number of serotonin (5HT) binding sites in rat striatum following an intrastriatal injection. We found that kainic acid injected into the striatum caused a dose-dependent increase in ipsilateral striatal 5-hydroxyindoleacetic acid (5HIAA) content, while not affecting the level of 5HT. There was no detectable change in 5HT metabolism in the contralateral striatum. The increase of 5HIAA was a reflection of increased 5HT turnover in the injected striatum as measured from the decline of 5HIAA after pargyline treatment or the rise of 5-hydroxytryptophan after benserazide treatment. There was also a concomitant increase of tryptophan hydroxylase activity. Kainic acid treatment resulted in an apparent decrease of the K mand increase of the V max for the pteridine cofactor and an increase of the V max for tryptophan by tryptophan hydroxylase. Kainic acid injection into the dorsal raphe nucleus caused a dose-dependent decrease in 5HT content of the dorsal raphe nucleus and in both striata, which are dorsal raphe nucleus projection areas. Our results suggest that 5HT formation in the striatum is normally modulated by an inhibitory neuronal feedback loop. Interruption of the loop by injecting kainic acid causes 5HT formation and tryptophan hydroxylase activity to increase in the ipsilateral but not contralateral striatum. Kainic acid apparently destroys 5HT neurons when injected close to the cell soma.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-1106
    Schlagwort(e): Neural transplantation ; Xenograft ; Fetal pig ; Rat striatum ; Rotational behavior ; Tyrosine hydroxylase immunohistochemistry ; Parkinson's disease
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A suspension of cells from embryonic day 21 fetal pig ventral mesencephalon was transplanted into the striatum of 20 immunosuppressed rats with 6-hydroxydopamine-induced lesions of the nigrostriatal dopamine pathway. Of these rats, 15 showed reduction of amphetamine-induced ipsilateral rotation by 9 weeks and complete reversal of rotation by 14–17 weeks. Animals maintained stable reversal of rotations (contralateral direction) until cessation of Cyclosporin A (CyA) treatment at 15–20 weeks. Within 4–9 weeks after CyA removal, these rats showed exclusively ipsilateral rotations during behavioral testing which were comparable to pre-transplant levels, suggesting that the grafts were rejected upon cessation of CyA treatment. Rats were sacrificed and tyrosine hydroxylase (TH) immunohistochemistry was performed at several time points, both on and off CyA, to examine a possible correlation between the degree of rotational behavior and the number of TH- positive surviving grafted cells. Staining showed large numbers (230–12,329) of TH-positive surviving cells in animals displaying a high degree of rotational correction (1.6 to -9.6 net ipsilateral rotations/min) after cessation of CyA treatment. Two control groups, those transplanted with nonneuronal cells from the pig ventral mesencephalon (n=5) and those receiving only daily CyA injections (n=4) showed no significant reduction of net ipsilateral rotations throughout the experiment. No TH-positive surviving cells were seen in the one non-neuronal transplant analyzed. This data demonstrates long-term retention of xenografted tissue with immunosuppression and its concomitant restoration of normal motor behavior in the rat model of Parkinson's disease.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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