Time-course of the effect of dietary L-tryptophan on plasma cortisol levels in rainbow trout Oncorhynchus mykiss

Lepage, Olivier; Vílchez, Inmaculada Molina; Pottinger, Tom G.; Winberg, Svante. 2003 Time-course of the effect of dietary L-tryptophan on plasma cortisol levels in rainbow trout Oncorhynchus mykiss. Journal of Experimental Biology, 206 (20). 3589-3599.

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Isolated juvenile rainbow trout were fed a feed supplemented with L-tryptophan (TRP) for 3, 7 or 28 days, after which they were either sampled directly (undisturbed) or subjected to a standardised stressor prior to sampling. Controls (stressed and undisturbed) received the same feed but without any supplementary TRP. Stress resulted in a significant elevation of plasma [cortisol] in fish fed control feed and in fish fed TRP-supplemented feed for 3 and 28 days. However, fish fed TRPsupplemented feed for 7 days did not show any significant elevation of plasma [cortisol] in response to stress. Plasma levels of adrenocorticotropin followed the same general pattern as cortisol. Plasma and brain [TRP] were elevated in fish fed TRP-supplemented feed. The amino acid TRP is the precursor of the monoamine neurotransmitter serotonin (5-hydroxytryptamine, 5-HT) and the brain 5- HT system is known to be involved in the control of the hypothalamic–pituitary–interrenal (HPI) axis. Fish fed TRP-supplemented feed showed elevated levels of 5- hydroxyindoleacetic acid (5-HIAA, a major 5-HT metabolite) in the hypothalamus and optic tectum. However, TRP treatment did not appear to result in any effects on brain dopaminergic activity and the effects on brain norepinephric activity do not support a role of norepinephrine in mediating the effects of TRP on HPI axis reactivity in rainbow trout.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: CEH Programmes pre-2009 publications > Water
UKCEH and CEH Sections/Science Areas: _ Environmental Chemistry & Pollution
ISSN: 0022-0949
Additional Information. Not used in RCUK Gateway to Research.: Click on the OFFICIAL URL to access freely available full text
Additional Keywords: serotonin, brain, fish, rainbow trout, Oncorhynchus mykiss, feed, stress, Salmonidae, aquaculture, cortisol, Oncorhynchus
NORA Subject Terms: Zoology
Biology and Microbiology
Date made live: 24 Jun 2015 11:13 +0 (UTC)

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