Journal article
Dietary l-tryptophan leaves a lasting impression on the brain and the stress response
Norwegian Institute for Water Research1
Norwegian University of Life Sciences2
National Institute of Aquatic Resources, Technical University of Denmark3
Section for Aquaculture, National Institute of Aquatic Resources, Technical University of Denmark4
University of Copenhagen5
Uppsala University6
Uni Research AS7
BioMar AS8
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.
Language: | English |
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Publisher: | Cambridge University Press |
Year: | 2017 |
Pages: | 1351-1357 |
ISSN: | 14752662 and 00071145 |
Types: | Journal article |
DOI: | 10.1017/S0007114517001428 |
ORCIDs: | 0000-0002-1350-8255 |