scholarly journals Stress elevates corticotropin-releasing factor (CRF) and CRF-binding protein mRNA levels in rainbow trout (Oncorhynchus mykiss)

2005 ◽  
Vol 186 (1) ◽  
pp. 123-130 ◽  
Author(s):  
C Doyon ◽  
V L Trudeau ◽  
T W Moon
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Plasma Cortisol ◽  
Preoptic Area ◽  
Binding Protein ◽  
Corticotropin Releasing Factor ◽  
Stress Axis ◽  
Control Group ◽  
Mrna Levels ◽  
Cortisol Levels

The objectives of this study were to characterize rainbow trout (Oncorhynchus mykiss) corticotropin-releasing factor (CRF)-binding protein (CRF-BP) cDNA and to examine the variations in CRF-BP and CRF mRNA levels in response to different intensities of stress. Trout were physically disturbed by a single or three consecutive periods of chasing until exhaustion followed by 2 h of recovery. The pituitary CRF-BP and preoptic area CRF1 mRNA contents were significantly increased only after repeated chasing events. Physical disturbance increased plasma cortisol levels with the largest change occurring in the group of trout that were exposed to repeated chasing events. Trout were also individually isolated in 120 l tanks or confined to 1.5 l boxes for 4, 24 or 72 h. CRF-BP mRNA levels in confined fish were greater than those of isolated fish at 72 h although there were no differences compared with the control group. CRF1 mRNA levels in the preoptic area were greater and remained elevated for a longer period in confined compared with isolated trout. Isolation led to a transient increase in plasma cortisol levels, but the higher cortisol values developed in the confined fish suggest that this treatment was more stressful than isolation. These results demonstrate that the intensity and duration of stress are important factors regulating CRF and CRF-BP mRNA levels in rainbow trout. We hypothesize that pituitary CRF-BP is involved in regulating the activity of the stress axis, possibly by reducing access to CRF1 receptors in the corticotropes.

CRF-related peptides contribute to stress response and regulation of appetite in hypoxic rainbow trout

2005 ◽  
Vol 289 (4) ◽  
pp. R982-R990 ◽  
Author(s):  
Nicholas J. Bernier ◽  
Paul M. Craig
Keyword(s):  
Rainbow Trout ◽  
Food Intake ◽  
Plasma Cortisol ◽  
Preoptic Area ◽  
Physiological Role ◽  
Corticotropin Releasing Factor ◽  
Stress Axis ◽  
Mrna Levels ◽  
Hypoxic Conditions ◽  
Hpi Axis

Hypoxia stress suppresses appetite in a variety of fish species, but the mechanisms mediating this response are not known. Therefore, given their anorexigenic and hypophysiotropic properties, we investigated the contribution of forebrain corticotropin-releasing factor (CRF) and urotensin I (UI) to the regulation of food intake and the hypothalamic-pituitary-interrenal (HPI) stress axis in hypoxic rainbow trout. Exposure to 50 and 35% O2 saturation for 24 h decreased food intake by 28 and 48%, respectively. The 35% O2 treatment also increased forebrain CRF and UI mRNA levels, plasma cortisol, and lactate. Exposure for 72 h to the same conditions resulted in similar reductions in food intake, increases in plasma cortisol proportional to the hypoxia severity, and increases in forebrain CRF and UI mRNA levels in the 50% O2 treatment. Relative to saline-infused fish, chronic intracranial infusion of the CRF receptor antagonist α-helical CRF(9–41) reduced the appetite-suppressing effects of 24-h exposure to 35% O2 and blocked the hypoxia-induced increase in plasma cortisol. Finally, forebrain microdissection revealed that 50 and 35% O2 exposure for 24 h specifically increases preoptic area CRF and UI mRNA levels in proportion to the severity of the hypoxic challenge and either has no effect or elicits small decreases in other forebrain regions. These results show that CRF-related peptides play a physiological role in regulating the HPI axis and in mediating at least a portion of the reduction in food intake under hypoxic conditions in rainbow trout and demonstrate that the response of forebrain CRF and UI neurons to this stressor is region specific.

scholarly journals Effects of Cortisol Administered through Slow-Release Implants on Innate Immune Responses in Rainbow Trout (Oncorhynchus mykiss)

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
R. Cortés ◽  
M. Teles ◽  
R. Trídico ◽  
L. Acerete ◽  
L. Tort
Keyword(s):  
Immune System ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Head Kidney ◽  
Lysozyme Activity ◽  
Innate Immune ◽  
Control Group ◽  
Mrna Levels ◽  
Cortisol Levels

Cortisol is a key hormone in the fish stress response with a well-known ability to regulate several physiological functions, including energy metabolism and the immune system. However, data concerning cortisol effects on fish innate immune system using a more controlled increase in cortisol levels isolated from any other stress related signaling is scarce. The present study describes the effect of doses of cortisol corresponding to acute and chronic levels on the complement and lysozyme activity in plasma of the rainbow trout (Oncorhynchus mykiss). We also evaluated the effects of these cortisol levels (from intraperitoneally implanted hydrocortisone) on the mRNA levels quantified by RT-qPCR of selected key immune-related genes in the liver, head kidney, and spleen. For that purpose, 60 specimens of rainbow trout were divided in to two groups: a control group injected with a coconut oil implant and another group injected with the same implant and cortisol (50 μg cortisol/g body weight). Our results demonstrate the role of cortisol as a modulator of the innate immune response without the direct contribution of other stress axes. Our results also show a relationship between the complement and lysozyme activity in plasma and mRNA levels in liver, supporting the important role of this organ in producing these immune system proteins after a rise of cortisol in the fish plasma.

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.

scholarly journals Differential Increase in Forebrain and Caudal Neurosecretory System Corticotropin-Releasing Factor and Urotensin I Gene Expression Associated with Seawater Transfer in Rainbow Trout

Endocrinology ◽  
2005 ◽  
Vol 146 (9) ◽  
pp. 3851-3860 ◽  
Author(s):  
Paul M. Craig ◽  
Haider Al-Timimi ◽  
Nicholas J. Bernier
Keyword(s):  
Rainbow Trout ◽  
Food Intake ◽  
Preoptic Area ◽  
Plasma Osmolality ◽  
Corticotropin Releasing Factor ◽  
Neurosecretory System ◽  
Mrna Levels ◽  
Caudal Neurosecretory System ◽  
Differential Increase ◽  
Crf System

Abstract Transfer to seawater (SW) in rainbow trout elicits an increase in plasma cortisol and a bout of anorexia. Although the corticotropin-releasing factor (CRF) system has known hypophysiotropic and anorexigenic properties, it is not known whether CRF-related peptides originating from either the forebrain or the caudal neurosecretory system (CNSS) play a role during SW acclimation. Therefore, we examined the effects of SW transfer on food intake, plasma osmolality, hypothalamic-pituitary-interrenal axis activity, and the expression of CRF and urotensin I (UI) in the forebrain and the CNSS. While SW transfer chronically suppressed food intake over a 2-wk period, it transiently increased plasma osmolality, ACTH, and cortisol. Similarly, 24 h after SW transfer, hypothalamic and preoptic area CRF mRNA levels were significantly increased but recovered to pretransfer levels within 7 d. Conversely, SW transfer elicited a delayed increase in hypothalamic UI mRNA levels and had no effect on preoptic area UI expression. In the CNSS, SW exposure was associated with parallel increases in CRF and UI mRNA levels from 24 h post transfer through 7 d. Finally, in situ hybridization demonstrated an extensive and overlapping pattern of CNSS CRF and UI expression. These results differentially implicate specific neuronal populations of the CRF system in the acute and chronic responses to a hyperosmotic stress and suggest that forebrain and CNSS CRF-related peptides have different roles in the coordinated response to fluid balance disturbances.

scholarly journals Heads or tails? Stressor-specific expression of corticotropin-releasing factor and urotensin I in the preoptic area and caudal neurosecretory system of rainbow trout

2007 ◽  
Vol 196 (3) ◽  
pp. 637-648 ◽  
Author(s):  
Nicholas J Bernier ◽  
Sarah L Alderman ◽  
Erin N Bristow
Keyword(s):  
Rainbow Trout ◽  
Stress Response ◽  
Preoptic Area ◽  
Corticotropin Releasing Factor ◽  
Neurosecretory System ◽  
Mrna Levels ◽  
Specific Expression ◽  
Caudal Neurosecretory System ◽  
Social Challenges ◽  
Positive Correlations

Corticotropin-releasing factor (CRF)- and urotensin I (UI)-expressing cells of the preoptic area (POA) and caudal neurosecretory system (CNSS) are considered key contributors to the regulation of the stress response in fish; however, the expression pattern of these neurons to environmental and social challenges have not been compared in a single study. Therefore, we characterized in rainbow trout (Oncorhynchus mykiss) the central distribution of CRF and UI expression and quantified the POA and CNSS mRNA levels of both transcripts in response to hyperammonemia, hypoxia, isolation, or subordination. The tissue distribution demonstrated that the POA and the CNSS are dominant sites of CRF and UI expression. Comparison of the plasma cortisol levels in response to the diverse treatments showed that subordination was the most severe stressor followed by hyperammonemia, isolation, and hypoxia. In the POA, with the exception of subordination that had no effect on UI expression, all stressors resulted in increase in CRF and UI mRNA levels. In the CNSS, while hyperammonemia was associated with increase in CRF and UI mRNA levels, and hypoxia induced an increase in CRF expression, isolation caused a decrease in the expression of both transcripts, and subordination had no effect. Independent of the stressor, we found strong positive correlations between CRF and UI expression in the POA and the CNSS, and no correlation in the expression of either gene between regions. Overall, the results demonstrate that the contribution of POA and CNSS CRF and UI neurons to the stress response in rainbow trout is stressor-, time-, and region-specific.

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