Cortisol effects on aerobic and anaerobic metabolism, nitrogen excretion, and whole-body composition in juvenile rainbow trout

G. De Boeck, D. Alsop, C. Wood

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

The influence of chronic cortisol elevation on metabolism, body composition, and fuel use patterns was examined in juvenile rainbow trout (Oncorhynchus mykiss). Measurements were performed in a control group (day 0) and in two experimental groups at days 3, 10, and 30 after treatment with a cortisol implant or a sham implant. All fish were fed 1% daily ration. Measured plasma cortisol levels were highest at day 3 and returned close to normal values by day 30 in cortisol-implanted fish. No plasma cortisol elevation was observed in the sham group. Growth was depressed in the cortisol-treated fish. Cortisol elevation resulted in increased plasma glucose concentrations during the entire experimental period, elevated CO2 production at day 3 and 30, and an elevated respiratory quotient (RQ) exceeding 1.0 on these days. Nitrogen excretion, estimated as the sum of ammonia-N plus urea-N excretion, and the nitrogen quotient exhibited small decreases at day 30. Total-N excretion, measured with a nitrogen oxidizer, was approximately twice the sum of ammonia-N plus urea-N excretion but exhibited a similar trend. Aerobic metabolism (routine O2 consumption) was higher on day 10 compared to sham-implanted fish, although not relative to day 0 control levels. Anaerobic metabolism increased substantially, as evidenced by pronounced plasma lactate elevations at days 3 and 10, a small increase in whole-body lactate on day 10, and the elevated RQ on days 3 and 30. Body composition exhibited an increase in total carbohydrate at days 3 and 10, mainly reflecting increased glycogen levels. Protein concentration was stable, indicating, in accord with the respirometry data, that protein usage did not fuel the increased metabolism or carbohydrate elevation. Redirection of nutrient uptake from food and/or mobilization of lipid stores (which decreased relative to the control group but not relative to shams) are suggested as possible energy sources for these actions of cortisol.

Original languageEnglish
Pages (from-to)858-868
Number of pages11
JournalPhysiological and Biochemical Zoology
Volume74
Issue number6
DOIs
StatePublished - Dec 1 2001

Fingerprint

Anaerobiosis
Oncorhynchus mykiss
anaerobiosis
Body Composition
Metabolism
body composition
cortisol
Hydrocortisone
Nitrogen
excretion
nitrogen
Chemical analysis
Fish
Fishes
Plasmas
respiratory quotient
fish
Ammonia
metabolism
lactates

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Physiology
  • Physiology (medical)

Cite this

Cortisol effects on aerobic and anaerobic metabolism, nitrogen excretion, and whole-body composition in juvenile rainbow trout. / De Boeck, G.; Alsop, D.; Wood, C.

In: Physiological and Biochemical Zoology, Vol. 74, No. 6, 01.12.2001, p. 858-868.

Research output: Contribution to journalArticle

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