Dietary l-tryptophan leaves a lasting impression on the brain and the stress response

Erik Höglund, Øyvind Øverli, Madelene Åberg Andersson, Patricia Isabel da Mota E. Silva, Danielle Caroline Laursen, Maria M Moltesen, Åshild Krogdahl, Joachim Schjolden, Svante Winberg, Marco A. Vindas, Ian Mayer, Marie Hillestad

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Abstract

Comparative models suggest that effects of dietary tryptophan (Trp) on brain serotonin (5-hydroxytryptamine; 5-HT) neurochemistry and stress responsiveness are present throughout the vertebrate lineage. Moreover, hypothalamic 5-HT seems to play a central role in control of the neuroendocrine stress axis in all vertebrates. Still, recent fish studies suggest long-term effects of dietary Trp on stress responsiveness, which are independent of hypothalamic 5-HT. Here, we investigated if dietary Trp treatment may result in long-lasting effects on stress responsiveness, including changes in plasma cortisol levels and 5-HT neurochemistry in the telencephalon and hypothalamus of Atlantic salmon. Fish were fed diets containing one, two or three times the Trp content in normal feed for 1 week. Subsequently, fish were reintroduced to control feed and were exposed to acute crowding stress for 1 h, 8 and 21 d post Trp treatment. Generally, acute crowding resulted in lower plasma cortisol levels in fish treated with 3×Trp compared with 1×Trp- and 2×Trp-treated fish. The same general pattern was reflected in telencephalic 5-HTergic turnover, for which 3×Trp-treated fish showed decreased values compared with 2×Trp-treated fish. These long-term effects on post-stress plasma cortisol levels and concomitant 5-HT turnover in the telencephalon lends further support to the fact that the extrahypothalamic control of the neuroendocrine stress response is conserved within the vertebrate lineage. Moreover, they indicate that trophic/structural effects in the brain underlie the effects of dietary Trp treatment on stress reactivity.
Original languageEnglish
JournalBritish Journal of Nutrition
Volume117
Issue number10
Pages (from-to)1351-1357
ISSN0007-1145
DOIs
Publication statusPublished - 2017

Keywords

  • l-Tryptophan
  • 5-HIAA 5-hydroxyindoleacetic acid
  • 5-HT 5-hydroxytryptamine (serotonin)
  • HPI hypothalamic–pituitary–interrenal
  • SSRI supplementation and serotonin reuptake inhibitors
  • Trp tryptophan
  • Long-term effects
  • Monoamines

Cite this

Höglund, E., Øverli, Ø., Åberg Andersson, M., Silva, P. I. D. M. E., Laursen, D. C., Moltesen, M. M., Krogdahl, Å., Schjolden, J., Winberg, S., Vindas, M. A., Mayer, I., & Hillestad, M. (2017). Dietary l-tryptophan leaves a lasting impression on the brain and the stress response. British Journal of Nutrition, 117(10), 1351-1357. https://doi.org/10.1017/S0007114517001428