Overwinter fasting and re-feeding in rainbow trout: plasma growth hormone and cortisol levels in relation to energy mobilisation

Pottinger, T.G.; Rand‐Weaver, Mariann; Sumpter, John P.

doi:10.1016/s1096-4959(03)00212-4

Cited by 106 publications

(69 citation statements)

References 79 publications

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“…Those on a high diet were fed 2% ± 0.01g body weight per day, whilst those fed on a low feed routine were only provided with 0.15% ± 0.01g body weight per day to induce fasting. Short-term food deprivation occurs in the wild due to limited food availability or low temperatures, and therefore fasting is a non-stressful natural process in rainbow trout causing a reduction in weight and condition factor (Pottinger et al, 2003); upon resumption of feeding, individuals quickly return to their former health status with no further ill-effects.…”

Section: Predation Risk and Diet Manipulationsmentioning

confidence: 99%

Plasticity of boldness in rainbow trout, Oncorhynchus mykiss: do hunger and predation influence risk-taking behaviour?

Thomson

Watts

Pottinger

et al. 2012

Hormones and Behavior

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Article (refereed) -postprintThomson, Jack S.; Watts, Phillip C.; Pottinger, Tom G.; Sneddon, Lynne U. 2012 Plasticity of boldness in rainbow trout, Oncorhynchus mykiss: do hunger and predation influence risk-taking behaviour? Hormones and Behavior, 61 (5). 750-757. 10.1016/j.yhbeh.2012.03.014 Contact CEH NORA team at noraceh@ceh.ac.ukThe NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. Boldness, a measure of an individual's propensity for taking risks, is an important determinant of fitness but is not necessarily a fixed trait. Dependent upon an individual's state, and given certain contexts or challenges, individuals may be able to alter their inclination to be bold or shy in response. Furthermore, the degree to which individuals can modulate their behaviour has been linked with physiological responses to stress. Here we attempted to determine whether bold and shy rainbow trout, Oncorhynchus mykiss, can exhibit behavioural plasticity in response to changes in state (nutritional availability) and context (predation threat). Individual trout were initially assessed for boldness using a standard novel object paradigm; subsequently, each day for one week fish experienced either predictable, unpredictable, or no simulated predator threat in combination with a high (2% body weight) or low (0.15%) food ration, before being reassessed for boldness. Bold trout were generally more plastic, altering levels of neophobia and activity relevant to the challenge, whereas shy trout were more fixed and remained shy. Increased predation risk generally resulted in an increase in the expression of three candidate genes linked to boldness, appetite regulation and physiological stress responses -ependymin, corticotrophin releasing factor and GABA A -but did not produce a significant increase in plasma cortisol. Plasticity of boldness in rainbow troutThe results suggest a divergence in the ability of bold and shy trout to alter their behavioural profiles in response to internal and exogenous factors, and have important implications for our understanding of the maintenance of different behavioural phenotypes in natural populations.

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Section: Predation Risk and Diet Manipulationsmentioning

confidence: 99%

Plasticity of boldness in rainbow trout, Oncorhynchus mykiss: do hunger and predation influence risk-taking behaviour?

Thomson

Watts

Pottinger

et al. 2012

Hormones and Behavior

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“…The induced expression of CPT I in mammals is regulated, in part, by the transcription factors and nuclear receptors, PPARa and PPARb . During fasting, plasma and cytosolic free fatty acids are elevated (Pottinger et al 2003). These fatty acids may act as ligands to activate PPARa and induce expression of CPT I in both liver and muscle.…”

Section: Gene Expressionmentioning

confidence: 99%

Regulation of Carnitine Palmitoyltransferase (CPT) I during Fasting in Rainbow Trout (Oncorhynchus mykiss) Promotes Increased Mitochondrial Fatty Acid Oxidation

Morash

McClelland

2011

Physiological and Biochemical Zoology

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Periods of fasting, in most animals, are fueled principally by fatty acids, and changes in the regulation of fatty acid oxidation must exist to meet this change in metabolic substrate use. We examined the regulation of carnitine palmitoyltransferase (CPT) I, to help explain changes in mitochondrial fatty acid oxidation with fasting. After fasting rainbow trout (Oncorhynchus mykiss) for 5 wk, the mitochondria were isolated from red muscle and liver to determine (1) mitochondrial fatty acid oxidation rate, (2) CPT I activity and the concentration of malonyl-CoA needed to inhibit this activity by 50% (IC 50 ), (3) mitochondrial membrane fluidity, and (4) CPT I (all five known isoforms) and peroxisome proliferator-activated receptor (PPARa and PPARb) mRNA levels. Fatty acid oxidation in isolated mitochondria increased during fasting by 2.5-and 1.75-fold in liver and red muscle, respectively. Fasting also decreased sensitivity of CPT I to malonyl-CoA (increased IC 50 ), by two and eight times in red muscle and liver, respectively, suggesting it facilitates the rate of fatty acid oxidation. In the liver, there was also a significant increase CPT I activity per milligram mitochondrial protein and in whole-tissue PPARa and PPARb mRNA levels. However, there were no changes in mitochondrial membrane fluidity in either tissue, indicating that the decrease in CPT I sensitivity to malonyl-CoA is not due to bulk fluidity changes in the membrane. However, there were significant differences in CPT I mRNA levels during fasting. Overall, these data indicate some important changes in the regulation of CPT I that promote the increased mitochondrial fatty acid oxidation that occurs during fasting in trout.

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“…Stress is a generalized response attributed to the fact that fish commonly have a complex of adaptive reactions to cope with stressors (1,2). For instance, stress has been reported to elevate plasma cortisol (3)(4)(5)(6)(7)(8), glucose levels (5,6,(9)(10)(11), and ventilatory frequency (12)(13)(14)(15) in fish. Although stress can be considered to be a generalized response, it can be modulated by specific stressor conditions (16).…”

Section: Introductionmentioning

confidence: 99%

“…Such modifying factors may be either a non-stressor or inherent to the stressor trait. For instance, sexual maturity (4), environmental color (17,18), heritability (7), age (3), and feeding state (8) are non-stressful conditions that modulate the stress response. On the other hand, intensity and duration are stressor characteristics that affect stress (1,2).…”

Section: Introductionmentioning

confidence: 99%

Stress responses of the fish Nile tilapia subjected to electroshock and social stressors

Barreto

Volpato

2006

Braz J Med Biol Res

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Plasma cortisol and glucose levels were measured in 36 adult Nile tilapia males, Oreochromis niloticus (standard length, mean ± SD, 14.38 ± 1.31 cm), subjected to electroshock and social stressors. Prestressor levels were determined 5 days after the adjustment of the fish to the experimental aquaria (1 fish/aquarium). Five days later, the effects of stressors on both cortisol and glucose levels were assessed. The following stressors were imposed for 60 min: pairing with a larger resident animal (social stressor), or a gentle electroshock (AC, 20 V, 15 mA, 100 Hz for 1 min every 4 min). Each stressor was tested in two independent groups, one in which stress was quantified immediately after the end of the 60-min stressor imposition (T60) and the other in which stress was quantified 30 min later (T90). Pre-stressor values for cortisol and glucose were not statistically different between groups. Plasma cortisol levels increased significantly and were of similar magnitude for both electroshock and the social stressor (mean ± SD for basal and final samples were: electroshock T60 = 65.47 ± 15.3, 177.0 ± 30.3; T90 = 54.8 ± 16.0, 196.2 ± 57.8; social stress T60 = 47.1 ± 9.0, 187.6 ± 61.7; T90 = 41.6 ± 8.1, 112.3 ± 26.8, respectively). Plasma glucose levels increased significantly for electroshock at both time points (T60 and T90), but only at T90 for the social stressor. Initial and final mean (± SD) values are: electroshock T60 = 52.5 ± 9.2, 115.0 ± 15.7; T90 = 35.5 ± 1.1, 146.3 ± 13.3; social stress T60 = 54. 8 ± 8.8, 84.4 ± 15.0; T90 = 34.5 ± 5.6, 116.3 ± 13.6, respectively. Therefore, electroshock induced an increase in glucose more rapidly than did the social stressor. Furthermore, a significant positive correlation between cortisol and glucose was detected only at T90 for the social stressor. These results indicate that a fish species responds differently to different stressors, thus suggesting specificity of fish stress response to a stressor.

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Overwinter fasting and re-feeding in rainbow trout: plasma growth hormone and cortisol levels in relation to energy mobilisation

Cited by 106 publications

References 79 publications

Plasticity of boldness in rainbow trout, Oncorhynchus mykiss: do hunger and predation influence risk-taking behaviour?

Plasticity of boldness in rainbow trout, Oncorhynchus mykiss: do hunger and predation influence risk-taking behaviour?

Regulation of Carnitine Palmitoyltransferase (CPT) I during Fasting in Rainbow Trout (Oncorhynchus mykiss) Promotes Increased Mitochondrial Fatty Acid Oxidation

Stress responses of the fish Nile tilapia subjected to electroshock and social stressors

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