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

2003 ◽  
Vol 206 (20) ◽  
pp. 3589-3599 ◽  
Author(s):  
O. Lepage
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Plasma Cortisol ◽  
Time Course ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Cortisol Levels

Differential expression of corticosteroid receptor genes in rainbow trout (Oncorhynchus mykiss) immune system in response to acute stress

2007 ◽  
Vol 64 (10) ◽  
pp. 1382-1389 ◽  
Author(s):  
Takashi Yada ◽  
Teruo Azuma ◽  
Susumu Hyodo ◽  
Tetsuya Hirano ◽  
E Gordon Grau ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Plasma Cortisol ◽  
Glucocorticoid Receptors ◽  
Acute Stress ◽  
Mrna Levels ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Corticosteroid Receptor ◽  
Polymerase Chain ◽  
Peripheral Blood Leucocytes

Expression of distinct corticosteroid receptor genes, glucocorticoid receptors 1 and 2 (GR-1 and GR-2, respectively) and mineralcorticoid receptor (MR), was quantified by real-time polymerase chain reaction (PCR) in peripheral blood leucocytes (PBL), spleen, and gill of rainbow trout (Oncorhynchus mykiss) after an acute netting stress. Plasma cortisol levels were significantly increased 2 h after stress and returned to prestress levels within 24 h. Consistent with changes in plasma cortisol, GR-2 mRNA levels in PBL increased significantly at 2 h after stress, returning to initial levels by 8 h. In contrast, GR-1 and MR levels in PBL decreased significantly at 24 h after stress, and these reduced levels were maintained for 7 days. Splenic mRNA levels of GR-1 and GR-2 also decreased at 8 h and 24 h after stress, returning to control levels by 7 days, whereas no significant change was observed in MR. In gill, there was no obvious change in corticosteroid receptor mRNA levels after stress, except for a transient decrease at 8 h in MR. These results suggest a variety of roles for the three corticosteroid receptors during immunosuppression in response to acute stress in trout.

Individual variation and interrelationships between swimming performance, growth rate, and feeding in juvenile rainbow trout (Oncorhynchus mykiss)

1998 ◽  
Vol 55 (7) ◽  
pp. 1583-1590 ◽  
Author(s):  
T Ryan Gregory ◽  
Chris M Wood
Keyword(s):  
Growth Rate ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Plasma Cortisol ◽  
Positive Relationship ◽  
Swimming Performance ◽  
Individual Performance ◽  
Significant Positive Relationship ◽  
Juvenile Rainbow Trout ◽  
Rainbow Trout Oncorhynchus Mykiss

Variation among individuals in specific growth rate (SGR), feeding, and two measures of swimming performance and their possible interrelationships were investigated in juvenile rainbow trout (Oncorhynchus mykiss) kept in groups on either satiation or half-satiation rations. Maximum sustainable velocity (Ucrit) was measured as an index of aerobic swimming performance and stamina (fatigue time in a fixed-velocity test at 6 body lengths ·s-1) as an index of anaerobic performance. Individual performance in both of these tests was found to be significantly repeatable. Trout fed on half-satiation ration exhibited significantly lower mean values of SGR and body size and higher levels of aggression-related fin damage, but no significant differences in stamina, relative or absolute Ucrit, glycogen content, or plasma cortisol. However, in these fish, there was a significant negative relationship between SGR and relative Ucrit, a significant positive relationship between SGR and stamina, and a significant positive relationship between SGR and total daily meal. None of these relationships were seen in fish fed to satiation. Plasma cortisol and tissue glycogen stores were not related to SGR. These results indicate that under the intensified competition of restricted ration, there are trade-offs between growth, feeding, and different types of swimming performance.

scholarly journals Elevation of plasma somatolactin concentrations during acidosis in rainbow trout (Oncorhynchus mykiss)

1996 ◽  
Vol 199 (5) ◽  
pp. 1043-1051 ◽  
Author(s):  
S Kakizawa ◽  
T Kaneko ◽  
T Hirano
Keyword(s):  
Rainbow Trout ◽  
Plasma Cortisol ◽  
Initial Level ◽  
Plasma Concentrations ◽  
Water Acidification ◽  
Acid Base ◽  
Exposed Fish ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Blood Ph ◽  
Cortisol Levels

Somatolactin (SL) is a putative pituitary hormone of the growth hormone (GH)/prolactin (PRL) family in fish; its physiological function has yet to be determined. Acidosis was induced in rainbow trout (Oncorhynchus mykiss) by exposure to acidic water (pH 4.5) or by exhaustive exercise, and plasma concentrations of SL, PRL and GH as well as other plasma parameters were examined. A decrease in blood pH was observed in fish from 1 day after water acidification until the end of the experiment at day 7. Plasma SL levels in the acid-exposed fish increased, reached a peak on day 1 and then returned to the initial level by day 4. No change was seen in plasma concentrations of PRL throughout the experiment. Plasma levels of GH, in contrast, decreased in the acid-exposed fish on days 2 and 4. Plasma cortisol levels in the acid-exposed fish were higher than the control level on days 4 and 7, although plasma cortisol levels did not increase above the initial level in response to water acidification. There was no significant change in the expression of SL-, PRL- and GH-mRNA in the pituitary gland. Levels of plasma Na+ and lactate were reduced 12 h after water acidification and remained low throughout the experiment. Exhaustive exercise in shallow water at neutral pH (7.5) resulted in a transient but pronounced acidosis, associated with increases in plasma SL, cortisol, Ca2+, phosphate and lactate levels. Plasma SL levels returned to the initial level along with the recovery of blood acid-base status. In contrast, plasma cortisol levels stayed elevated even 24 h after exercise. There was no correlation between plasma PRL and GH levels and blood pH. Elevation of plasma SL levels during acidosis suggests the possible involvement of SL in acid-base regulation in rainbow trout.

Elevated dietary intake of L-tryptophan counteracts the stress-induced elevation of plasma cortisol in rainbow trout (Oncorhynchus mykiss)

2002 ◽  
Vol 205 (23) ◽  
pp. 3679-3687 ◽  
Author(s):  
Olivier Lepage ◽  
Olof Tottmar ◽  
Svante Winberg
Keyword(s):  
Rainbow Trout ◽  
Plasma Cortisol ◽  
Elevated Plasma ◽  
Monoamine Neurotransmitter ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Serotonergic Activity ◽  
Commercial Feed ◽  
Pelleted Feed ◽  
Cortisol Levels ◽  
Neuroendocrine Axis

SUMMARYJuvenile rainbow trout were isolated in individual compartments and allowed to acclimate for 1 week, during which they were fed commercial trout pellets. The feed was then replaced by pelleted feed supplemented with L-tryptophan(TRP) at two, four or eight times the concentration in the commercial feed. Fish were fed these supplemented feeds daily to satiety for 1 week, after which half of the fish were stressed, by lowering the water level for 2 h,while the remaining fish were left undisturbed. In undisturbed fish,supplementary dietary TRP resulted in slightly elevated plasma cortisol levels. In response to the stress, fish that had been fed control feed showed elevated plasma cortisol levels, but fish fed the TRP-supplemented feed displayed a significant reduction in this stress-induced elevation of plasma cortisol levels. Plasma and brain TRP levels were elevated in fish fed TRP-supplemented feed. TRP is the precursor of the monoamine neurotransmitter serotonin. Brain serotonergic activity was elevated by stress and also tended to be increased by elevated dietary TRP intake. The central serotonergic system is involved in the control of the hypothalamic—pituitary—interrenal axis, the action of serotonin being to stimulate or inhibit this neuroendocrine axis through different projections.

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