Neurochemical Research

, Volume 5, Issue 3, pp 223–239 | Cite as

l-Kynurenine Its synthesis and possible regulatory function in brain

  • E. Martin Gál
  • Arnold D. Sherman


One pathway by which tryptophan is metabolized in the brain as well as in the periphery is through cleavage of the indole ring to formylkynurenine and then kynurenine. Indoleamine-2,3-dioxygenase, the enzyme that catalyzes this clavage, and kynurenine are distributed all across the different anatomic regions of brain. Approximately 40% of the kynurenine in brain is synthesized there, the remainder having come from plasma. Tryptophan loading, which has been used both experimentally and therapeutically as a means of increasing tryptophan conversion to serotonin, also increases kynurenine formation in the brain and in the periphery. Because of the formation of kynurenine, which competes for cerebral transport and cellular uptake ofl-tryptophan, and because of substrate inhibition on tryptophan hydroxylase, excessively high doses of tryptophan may actually decrease the production of cerebral serotonin and 5-hydroxyindoleacetic acid.


Serotonin Tryptophan Indole Regulatory Function Cellular Uptake 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Plenum Publishing Corporation 1980

Authors and Affiliations

  • E. Martin Gál
    • 1
  • Arnold D. Sherman
    • 1
  1. 1.Neurochemical Research Laboratories Department of Psychiatry College of MedicineUniversity of IowaIowa City

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