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Increase of brain tryptophan and stimulation of serotonin synthesis by salicylate
Author(s) -
Tagliamonte A.,
Biggio G.,
Vargiu L.,
Gessa G. L.
Publication year - 1973
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1973.tb00054.x
Subject(s) - tryptophan , tryptophan hydroxylase , serotonin , stimulation , chemistry , metabolism , biochemistry , endocrinology , medicine , amino acid , biology , receptor , serotonergic
I ndirect evidence indicates that the rate‐limiting step in the synthesis of brain 5‐HT is the concentration of tryptophan in brain and not, as previously considered (G reen and S awyer , 1966), tryptophan hydroxylase. In fact this enzyme has a K m for its substrate much higher than the concentration of tryptophan normally present in the mammalian brain (J equier , L ovenberg and S joerdsma , 1967; J equier , R obinson , L ovesberg and S joerdsma , 1969; M cgeer , P eters and M cgeer , 1968). Tryptophan is the only amino acid circulating in plasma which is highly bound to serum proteins (M cmenamy and O ncley , 1958). We have previously shown that the free fraction of serum tryptophan controls the concentration of brain tryptophan and, therefore, 5‐HT synthesis as well (T agliamonte , B iggio and G essa , 1971d; G essa , B iggio and T agliamonte , 1972). Salicylate has been shown to displace tryptophan from its protein binding in plasma and to raise the free tryptophan concentration (M carthur and D awkins , 1969; S mith and L akatos , 1971). These considerations prompted us to study the effect of salicylate on tryptophan concentrations and 5‐HT metabolism in brain.