Effect of acute L-tryptophan exposure on the brain serotonergic system and behavior in the male medaka

Tomoyuki Koutoku, Rong Zhang, Tetsuya Tachibana, Yuji Oshima, Mitsuhiro Furuse

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11 Citations (Scopus)


The aim of this study was to investigate the effect of exposure to L-tryptophan (TRP) on the metabolism of 5-hydroxytryptamine (5HT) and behavior of medaka. In the first experiment, the fish were exposed to a 0, 1, 2 or 4 g/l of TRP solution for 24 hr. Although no significant difference in the brain 5HT content was detected, 5-hydroxyindoleacetic acid (5HIAA), a major 5HT metabolite, increased in a dose-dependent fashion. In the second experiment, the fish were maintained in a 0 or 4 g/l of TRP solution for 28 hr, and then their behaviors were monitored. The fish reared in under TRP solution were divided into two groups and transferred to either fresh water or a TRP solution. The locomotion of the TRP-treated group significantly increased compared to the control group irrespective of water conditions. It was suggested that TRP exposure activated the brain 5HTnergic systems and stimulated behavior of medaka.

Original languageEnglish
Pages (from-to)121-124
Number of pages4
JournalZoological science
Issue number2
Publication statusPublished - Feb 1 2003


All Science Journal Classification (ASJC) codes

  • Animal Science and Zoology

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