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  • 1
    ISSN: 1432-2072
    Keywords: Caudate nucleus ; Hippocampus ; Serotonin ; Dopamine ; Chlorimipramine ; Fluvoxamine ; 6-Nitroquipazine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Slices of rabbit hippocampus or caudate nucleus were incubated with [3H]-5-HT (0.1 µM, 60 min) or with [3H]-DA. In hippocampal tissue, the 5-HT uptake blockers chlorimipramine, fluvoxamine, and 6-nitroquipazine (0.1, 1, 10 µM) reduced the percentage content of [3H]-5-HT in a concentration dependent manner. The degree of inhibition of [3H]-5-HT content produced by the 5-HT uptake inhibitors was not affected by the MAO inhibitors pargyline or amezinium (which by themselves enhanced [3H] loading) or the catecholamine uptake inhibitor nomifensine (which by itself did not affect [3H] loading). In caudate nucleus tissue, however, the [3H]-5-HT accumulation was reduced only at the highest concentration of the 5-HT uptake blockers (10 µM). In the additional presence of the MAO inhibitors or nomifensine (which by themselves increased or diminished, respectively, the [3H] labelling) the 5-HT uptake inhibitors became more potent in reducing the percentage [3H]-5-HT accumulation of caudate nucleus slices. These results indicate (1) that a false labelling of [3H]-5-HT into dopaminergic terminals in the caudate nucleus can be prevented by nomifensine, (2) that the 5-HT uptake blockers seem to accumulate within the dopaminergic terminals, where they may display a MAO inhibitory property. The 5-HT uptake blockers were ineffective on the percentage tritium accumulation of caudate nucleus slices incubated with [3H]-DA, regardless of the presence of pargyline or nomifensine. Tritiated DA and deaminated [3H]-metabolites were separated in the superfusate of [3H]-DA-release experiments in caudate nucleus tissue. In the presence of 6-nitroquipazine the percentage efflux of unmetabolized [3H]-DA was significantly enhanced in a concentration and time dependent manner. In comparison to 6-nitroquipazine, fluvoxamine was less potent in that respect. 6-Nitroquipazine inhibited the electrically evoked [3H]-DA and [3H]-ACh release from caudate nucleus slices in a concentration dependent manner. The effects on [3H]-DA release were abolished in the presence of pargyline. The inhibition of [3H]-ACh release was significantly diminished by the D2-receptor antagonist domperidone. In conclusion, some 5-HT-related drugs may diminish the release of ACh from caudate nucleus slices via an enhanced dopaminergic transmission due to inhibition of MAO within the dopaminergic terminals.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1433-8491
    Keywords: Extracerebral and Intracerebral Processes ; Different EEG Blocking while Eyes Open ; Blocking of α and Abnormal Waves ; Tumors and Haematomas of Cerebral Hemispheres ; Extra- und intracerebrale Prozesse ; Verschiedene EEG-Blockierung durch Augenöffnen ; Blockierung von Alpha- und Deltawellen ; Tumoren und Hämatome der Großhirnhemisphären
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei einer Gruppe von 45 Patienten mit einem durch Operation oder Sektion gesicherten extra oder intracerebralen raumfordernden Prozeß wird das Verhalten der physiologischen und pathologischen Aktivität im EEG bei Ableitung mit offenen Augen untersucht. Es ließ sich zeigen, daß bei extraoerebralen Prozessen (Meningiom, Sub- und Epiduralhämatom) im Gegensatz zu den intracerebralen Tumoren sowohl die Alphatätigkeit wie auch die pathologische Aktivität über der betroffenen Hemisphäre durch Augenöffnen blockiert werden. Die pathophysiologischen Aspekte werden diskutiert. Außerdem wird auf die Bedeutung der Befunde für die EEG-Praxis als einfaches differentialdiagnostisches Kriterium bei extra- und intracerebralen Prozessen hingewiesen.
    Notes: Summary The blocking reaction of the EEG was investigated in 45 patients with intracranial extra- and intracerebral space occupying processes. It was shown, that in 15 out of 17 cases with an extracerebral process (meningeoma, sub- and epidural haematoma) the δ as well as the α activity over the affected hemisphere were blocked by opening the eyes. In contrast the δ activity on the affected side was blocked in only 3 out of 28 cases with intracerebral tumors (gliomas) during eyes open. Besides some interesting patho-physiological aspects of this observation, the statistical differences between the two groups are a useful, though limited EEG-criterion for differentiating between extra- and intracerebral space-occupying processes.
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  • 3
    ISSN: 1432-1912
    Keywords: A1 adenosine receptors ; Serotonin release ; Hippocampus ; Caudate nucleus ; Rabbit ; Endogenous adenosine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of A1 adenosine receptor ligands on the evoked release of serotonin (5-HT) were studied in slices of the hippocampus and the caudate nucleus of the rabbit, preincubated with 3H-5-HT. In hippocampal tissue electrical stimulation elicited a release which was inhibited by the adenosine receptor agonist N6-cyclohexyladenosine (CHA) and enhanced by the selective A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). The concentration-response curve of CHA was shifted to the right by DPCPX. The shift corresponded to a pA2 value of 9.4 for DPCPX. CHA, R-N6-phenylisopropyladenosine (R-PIA) and DPCPX were ineffective in caudate nucleus tissue. When instead of electrical pulses high K+ was used to induce 5-HT release in the presence of the Na+ channel blocker tetrodotoxin (TTX), which was present in order to exclude effects mediated by interneurones, CHA was equally effective in the hippocampus but again failed to modify 5-HT release in the caudate nucleus. The disinhibition by DPCPX of the evoked 5-HT release was used to calculate the extracellular concentration of endogenous adenosine at the A1 receptor. The calculation greatly depended on the dissociation constant of adenosine at the A1 receptor. It is concluded that A1 adenosine receptors, activated by the endogenous agonist at a concentration of about 0.7 μmol/l, are located on serotonergic nerve endings in the hippocampus, but not in the caudate nucleus. The estimated extracellular concentration of endogenous adenosine is in reasonable agreement with actually measured concentrations reported in the literature.
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