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The effect of exercise on plasma cortisol and blood sugar levels in the rainbow trout, Salmo gairdnerii Richardson
Author(s) -
Zelnik P. R.,
Goldspink G.
Publication year - 1981
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.1981.tb05809.x
Subject(s) - rainbow trout , salmo , medicine , endocrinology , biology , trout , nocturnal , hydrocortisone , circadian rhythm , zoology , fish <actinopterygii> , fishery
Preliminary experiments were performed to determine the diurnal variation in cortisol, using trout which had been cannulated three days previously. These results indicated that cortisol levels were reasonably stable between 10.00 and 18.00 hours, thus permitting experimentation during this period without diurnal fluctuations masking the cortisol response. Uncannulated fish were exercised in a flume for 2 h at 1, 2.6 and 5 bl s ‐1 and plasma samples taken from groups of five animals at 15, 30, 60 and 120 min after the start of exercise and at 1½, 12 and 24 h after the exercise ceased. The cortisol levels in all cases were elevated after 15 min, but the magnitude of the elevation increased with swimming speed. At 1 bl s ‐1 the cortisol levels increased from 76.4 (± 20.4) to 129.2 (± 20.4) ng ml ‐1 [mean (± s.d. )]. At 2.6 bl s ‐1 the increase was from 72.4 (± 17.1) to 254.4 (± 34.4) ng ml ‐1 and at 5 bl s ‐1 the increase was from 69.5 (± 27.5) to 326.4 (± 39.0) ng ml ‐1 . The cortisol levels were stable over the exercise period and all groups recovered to baseline levels after 24 h, though the sample taken 12 h after the termination of exercise was elevated due to regular nocturnal increases in cortisol levels. There were no dramatic changes in blood sugar levels during and after exercise at 1 and 3.2 bl s ‐1 .