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  • 1975-1979  (9)
  • 1
    Electronic Resource
    Electronic Resource
    A STUDY OF PROPOSED DETERMINANTS OF BRAIN TRYPTOPHAN CONCENTRATION IN RATS AFTER PORTOCAVAL ANASTOMOSIS OR SHAM OPERATION (1978)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 31 (1978), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Liver dysfunction was produced in rats by surgical portocaval anastomosis (PCA), and the time-course of changes in brain tryptophan and 5-HT metabolism studied in relation to plasma changes possibly influencing brain tryptophan concentration.Brain tryptophan and 5-hydroxyindolylacetic acid (5-HIAA) levels were increased greatly and maximally on the day after PCA and remained high. 5-HT changes were less marked but had a similar time-course. Plasma total tryptophan was little changed but plasma free tryptophan was raised. The latter change showed a similar time-course to that of brain tryptophan but was not large enough to account completely for it. Sham operation was followed by significant but transient increases in plasma free tryptophan, brain tryptophan and 5-HIAA but these were much smaller than after PCA.Brain tryptophan did not correlate with plasma total tryptophan either in control or PCA rats but it correlated significantly with plasma free tryptophan in both groups. However brain levels were much higher in PCA rats than in controls with similar plasma free tryptophan levels at all times from the first day after operation. The increase of brain tryptophan in anastomosed rats not accounted for by plasma free tryptophan was explained neither by insulin changes nor by an increase of the insulin/glucagon ratio nor by changes in plasma concentrations of those amino acids which compete with tryptophan for entry into brain. The results therefore indicate an unknown influence on brain tryptophan concentration in PCA rats. As tyrosine changes in brain and plasma after PCA were very similar to those of tryptophan this influence may not be specific to tryptophan. Results suggest that under the conditions used brain tryptophan concentrations of both PCA and control rats are more influenced by changes of plasma free tryptophan concentration than by changes of plasma concentrations of competing amino acids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1978.tb06250.x
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  • 2
    Electronic Resource
    Electronic Resource
    METABOLISM OF A TRYPTOPHAN LOAD IN THE HYPOTHALAMUS AND OTHER BRAIN REGIONS (1975)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 25 (1975), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— Results confirm previous findings that after injecting rats with 50mg/kg tryptophan the percentage increase of 5-hydroxytryptamine metabolism (as shown by 5-hydroxyindolylacetic acid changes) is particularly small in the hypothalamus. However, 15–30 min after tryptophan injection (when brain 5-hydroxytryptamine changes were maximal) percentage 5-hydroxytryptamine increases in the hypothalamus and in the rest of the brain were comparable. The small 5-hydroxyindolylacetic acid changes in the hypothalamus are consistent with a long 5-hydroxytryptamine turnover time therein as indicated by experiments using pargyline or probenecid and by the relatively small increases of 5-hydroxytryptamine after injecting tryptophan into tranylcypromine treated rats. When 5-hydroxytryptamine synthesis was partially inhibited by p-chlorophenylalanine and tryptophan was injected, there was a large percentage rise of hypothalamic 5-hydroxytryptamine but the concentration found in rats given neither drug was not attained and 5-hydroxyindolylacetic acid showed little change. Elsewhere in the brain 5-hydroxytryptamine attained concentrations comparable to those in rats given neither drug and 5-hydroxyindolylacetic acid rose considerably. Results are discussed in relation to the contributions made to brain 5-hydroxytryptamine turnover by functional and non-functional metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1975.tb06961.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Transmitter precursors and metabolites in human ventricular cerebrospinal fluid (1976)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 26 (1976), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1976.tb01520.x
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    MELANIN FORMATION BY HUMAN BRAIN IN VITRO (1975)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 24 (1975), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— A quantitative radiometric assay utilising incorporation of 14C from labelled precursors as a measure of melanin formation by human brain in vitro is described. The assay was validated by comparison with various criteria of melanin formation.Catecholamines, DOPA and 5HT were precursors for brain melanin formation. Melanin formation was detected in all brain regions studied and was highest in substantia nigra and striatum.The assay was used to evaluate various hypotheses of brain melanin formation. No evidence for enzymic activity was found and it is concluded that brain melanin formation may be a largely non-enzymic process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1975.tb03887.x
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  • 5
    Electronic Resource
    Electronic Resource
    EFFECTS OF CHRONIC PORTO-CAVAL ANASTOMOSIS ON BRAIN TRYPTOPHAN, TYROSINE AND 5-HYDROXYTRYPTAMINE (1975)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 24 (1975), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: —Three weeks after porto-caval anastomosis, tryptophan and 5-hydroxyindolylacetic acid concentrations were-greatly increased in rat brain regions. 5-Hydroxytryptamine showed smaller increases. Midbrain tyrosine and muscle tyrosine and tryptophan concentrations were also increased. Striatal dopa-mine concentration was not significantly changed. Unlike previous results from acute liver failure, brain tryptophan changes in this chronic study did not simply reflect plasma-free tryptophan changes. Midbrain tryptophan/plasma-free tryptophan ratio and midbrain tyrosine/plasma tyrosine ratio both rose, suggesting increased effectiveness of uptake of these amino acids from plasma by brain. Corresponding muscle/plasma ratios were unaltered by the porto-caval anastomosis. Uptake of tryptophan from buffer by cerebral cortex slices was unaffected. Results on control animals illustrate the importance of plasma-free tryptophan in the normal physiological control of brain tryptophan.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1975.tb03678.x
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  • 6
    Electronic Resource
    Electronic Resource
    The relevance of both plasma free tryptophan and insulin to rat brain tryptophan concentration (1976)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 27 (1976), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1976.tb01598.x
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Factors influencing effect of hydrocortisone on rat brain tryptophan metabolism (1975)
    [s.l.] : Nature Publishing Group
    Nature 255 (1975), S. 170-170 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] THE concentrations of rat brain 5-hydroxytryptamine (5-HT) and its metabolite 5-hydroxyindole acetic acid (5-HIAA) have been found to be decreased by injection of hydrocortisone1"3 or other corticosteroids4. Benkert and Matussek5 did not, however, observe changes in 5-HT concentration at various ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/255170a0
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  • 8
    Electronic Resource
    Electronic Resource
    Control of brain tryptophan concentration in rats on a high fat diet (1976)
    [s.l.] : Nature Publishing Group
    Nature 262 (1976), S. 142-143 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Male Sprague?Dawley rats (200?220 g) (Anglia Laboratory Animals) housed three per cage were maintained on ALGH standard rodent diet (Grain Harvesters) and tap water ad libitum and subjected to a 6h:18h light: dark cycle. After a 5-d adaptation period, food but not water was withdrawn at 1600 and on ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/262142a0
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  • 9
    Electronic Resource
    Electronic Resource
    The contribution of tryptamine to the behavioural effects of l-tryptophan in tranylcypromine-treated rats (1978)
    Springer
    Psychopharmacology 57 (1978), S. 71-76 
    Details
    ISSN: 1432-2072
    Keywords: 5-Hydroxytryptamine ; Tryptamine ; monoamineoxidase inhibitors ; Activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats pretreated with the monoamine oxidase inhibitor tranylcypromine and given l-tryptophan develop a characteristic behavioural syndrome. A comparison of the behavioural effects of tranylcypromine plus l-tryptophan (50 and 100 mg/kg) showed a small increase in locomotor activity and a greater increase in the behavioural score with the higher dose. This was associated with a proportionately smaller increase in brain 5-hydroxytryptamine (5-HT) than in brain tryptamine and no change in spinal cord 5-HT. Tryptamine (1–5 mg/kg) in the presence of tranylcypromine produced behavioural effects very similar to those occurring when l-tryptophan is given to tranylcypromine-pretreated rats. Increasing brain tryptamine, by the injection of tryptamine (0.75 mg/kg), enhanced the behavioural effects of tranylcypromine plus l-tryptophan (50 mg/kg) without altering brain 5-HT. Para-chlorophenylalanine pretreatment, which reduced brain 5-HT, prevented the behavioural effects of tryptamine. Inhibition of peripheral decarboxylase with R04-4602 (50 mg/kg) reduced brain tryptamine and did not alter brain 5-HT, but reduced the locomotor activity and the behavioural score of rats given tranylcypromine and l-tryptophan (100 mg/kg). The results suggest that brain tryptamine changes are partly responsible for the behavioural effects of tranylcypromine plus l-tryptophan and that some of this tryptamine is of extracerebral origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00426960
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