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  • 1975-1979  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 27 (1976), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— Vanillylmandelic acid (VMA) and 3-methoxy-4- hydroxyphenylglycol (MHPG) were measured in rat brain by a mass fragmentographic procedure. The concentration of VMA and MHPG in whole brain is 11 and 533 pmol/g, respectively. Both compounds were found in all areas of brain studied with VMA, as a percentage of both metabolites, ranging between about 1 and 8%. From the decline of the compounds after pargyline. 75 mg/kg i.p., we calculated that the rate of formation of VMA is 15 and for MHPG 202 pmol/g per h. The fractional rate of elimination of VMA and MHPG is 1.4 and 0.38 h−1, respectively. The rapid rate of loss of VMA suggests that it is transported from brain. However, we were unable to block the elimination of VMA from brain by treatment with probenecid. In contrast, the elimination of MHPG could be blocked by treatment with probenecid. Our study adds support to the notion that MHPG is a major whereas VMA is a minor product of norepinephrine metabolism in brain.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Neurochemical research 1 (1976), S. 679-682 
    ISSN: 1573-6903
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 306 (1979), S. 173-177 
    ISSN: 1432-1912
    Keywords: Serotonin turnover ; Kainic acid ; Corpus striatum ; Feedback regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 253 (1975), S. 29-31 
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Neurochemical research 1 (1976), S. 47-52 
    ISSN: 1573-6903
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract 3-Methoxy-4-hydroxymandelic acid (VMA) is transported into the isolated choroid plexus against a concentration gradient by a saturable, energy-dependent system. The apparentK m for transport is 35 nM and theV max is 1 pmol/mg tissue/hr. Concentrations of probenecid (0.1 mM) that block the transport of other acidic biogenic amine metabolites did not block the transport of VMA. The transport system of the choroid plexus probably plays a role in clearing VMA from the CSF.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Neurochemical research 2 (1977), S. 657-669 
    ISSN: 1573-6903
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A gas chromatographic-mass spectrometric method was developed for analyzing phenylalanine and tyrosine (Tyr) in plasma and brain. With this procedure, we were able to show that18O2 is incorporated into Tyr in vivo and that the presence of18O-Tyr in plasma is a relative measure of phenylalanine hydroxylating activity. Treatment withp-chlorophenylalanine decreases the18O incorporation into Tyr. Because of the simplicity of the procedure and its easy adaptability to human studies, the incorporation of18O2 into endogenous constituents might serve as a useful diagnostic procedure for some metabolic disorders, such as phenylketonuria. These results also indicate that labeling with18O cannot be used to measure the turnover rate of brain catecholamines as previously proposed.
    Type of Medium: Electronic Resource
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