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- Altimiras, Jordi, 1967-, et al.
(author)
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Gastrointestinal blood flow and postprandial metabolism in swimming sea bass dicentrarchus labrax
- 2008
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In: Physiological and Biochemical Zoology. - : University of Chicago Press. - 1522-2152 .- 1537-5293. ; 81:5, s. 663-672
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Journal article (peer-reviewed)abstract
- In trout and salmon, the metabolic costs of exercise and feeding are additive, which would suggest that gastrointestinal blood flow during exercise is maintained to preserve digestive and absorptive processes related to the specific dynamic action (SDA) of food. However, in most published studies, gastrointestinal blood flow drops during swimming, hypoxia, and general stress. To test whether gastrointestinal blood flow is spared during exercise after feeding, sea bass were instrumented with flow probes to measure cardiac output and celiacomesenteric blood flow while swimming in a respirometer before and after feeding. Swimming at 2 body lengths per second (bl s-1) increased metabolic rate considerably more than did feeding (208% vs. 32% increase, respectively, relative to resting), and a similar pattern was observed for cardiac output. In unfed fish, resting gastrointestinal blood flow was mL 13.8 ± 0.5 min-1 kg-1. After feeding, resting gastrointestinal blood flow increased by 82% but then decreased progressively with increasing swimming speeds. At 2 bl s-1, gastrointestinal blood flow in fed fish was not significantly different compared with that in unfed swimming fish, and, therefore, the data do not support the gastrointestinal sparing hypothesis. The magnitude of the SDA was maintained despite the decrease in gastrointestinal blood flow and the consequent reduction in oxygen supply to the gut. An estimate of maximal oxygen flow to the gastrointestinal tract after feeding yielded 2.6 mmol O2 h-1 kg-1, but this amount is not able to cover the oxygen demand of 3.16 mmol O2 h -1 kg-1. Therefore, the SDA must reflect metabolic processes in tissues other than those directly perfused by the celiacomesenteric artery. © 2008 by The University of Chicago. All rights reserved.
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| 2. |
- Altimiras, Jordi, 1967-, et al.
(author)
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Intrinsic autoregulation of cardiac output in rainbow trout (Oncorhynchus mykiss) at different heart rates
- 2004
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In: J Exp Biol. - : The Company of Biologists. ; 207:Pt 2, s. 195-201
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Journal article (peer-reviewed)abstract
- Intrinsic regulation of the heart in teleosts is partly driven by central venous pressure, which exerts a modulatory role on stroke volume according to the well-known Frank-Starling mechanism. Although this mechanism is well understood from heart perfusion studies, less is known about how this mechanism operates in vivo, where heart rate varies markedly. We used zatebradine, a bradycardic agent, to attain resting heart rates in surgically instrumented animals. A dose of zatebradine of 2.79+/-0.47 mg l(-1) decreased heart rate by half, from 44.4+/-4.19 beats min(-1) to 22.1+/-1.9 beats min(-1). Zatebradine had no significant effect on the peripheral vasculature and no inotropic effects, so was a suitable pharmacological agent with which to manipulate heart rate. When heart rate halved, cardiac output dropped to 87.5+/-4.6% of the control value, due to the concomitant increase in stroke volume to 165+/-13%. In vivo recordings of venous pressure at varying heart rates indicated that the partial compensation in cardiac output was possible through an increase in pressure in the sinus venosus, from -0.06+/-0.04 kPa at a control heart rate of 58.3+/-3.5 beats min(-1) (N=10) to 0.07+/-0.05 kPa after injection of zatebradine (4 mg kg(-1)). The operation of the so-called time-dependent autoregulatory mechanism was further demonstrated in perfused hearts. The positive pressures recorded in the sinus venosus at low heart rates coincident with non-invasive measurements in trout suggest that atrial filling in trout is more dependent on the build-up of pressure in the venous circulation (vis-a-tergo filling) than a suction mechanism during ventricular contraction (vis-a-fronte filling).
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| 5. |
- Crossley, II, Dane A., et al.
(author)
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Ontogeny of baroreflex control in the American alligator Alligator mississippiensis
- 2003
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In: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 206, s. 2895-2902
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Journal article (peer-reviewed)abstract
- Baroreflex regulation appears in different species at different points in embryonic development. This study was designed to understand the development of the baroreflex in embryos of the American alligator at four different points of embryonic development (60%, 70%, 80% and 90% of a total incubation period of 72 days) and in 1-week-old hatchlings. Data from a separate study on 1-year-old alligators were included for comparison. The gain of the cardiac limb of the baroreflex was calculated from heart rate changes triggered by pharmacological manipulation of arterial pressure with sodium nitroprusside and phenylephrine. The results demonstrated that a vagally mediated hypertensive baroreflex was present during the final 30% of alligator development. A hypotensive baroreflex was not present in embryos but appeared in hatchlings, mediated by a combined effect of vagal and sympathetic efferents. Absolute baroreflex gain was maximal at 80% of incubation (41.22 beats kPa–1 min–1) and dropped thereafter, reaching a minimum in 1-year-old alligators (9.69 beats kPa–1 min–1). When the baroreflex gain was normalized to resting arterial pressure and heart rate, the maximum gain was observed in 1-year-old alligators (normalized index of 2.12 versus 0.75 in hatchlings and 0.69 as the highest gain in embryos). In conclusion, baroreflex regulation appeared during embryonic development with a substantial gain. These findings indicate that embryonic development is a period of preparation for cardiovascular regulatory mechanisms that will be necessary in adult life and that the baroreflex control mechanism is required for cardiovascular control during ontogeny.
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| 6. |
- Crossley II, Dane A., et al.
(author)
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Cardiovascular development in embryos of the American alligator Alligator mississippiensis : effects of chronic and acute hypoxia
- 2005
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In: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 208, s. 31-39
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Journal article (peer-reviewed)abstract
- Chronic hypoxic incubation is a common tool used to address the plasticity of morphological and physiological characteristics during vertebrate development. In this study chronic hypoxic incubation of embryonic American alligators resulted in both morphological (mass) and physiological changes. During normoxic incubation embryonic mass, liver mass and heart mass increased throughout the period of study, while yolk mass fell. Chronic hypoxia (10%O2) resulted in a reduced embryonic mass at 80% and 90% of incubation. This reduction in embryonic mass was accompanied by a relative enlargement of the heart at 80% and 90% of incubation, while relative embryonic liver mass was similar to the normoxic group. Normoxic incubated alligators maintained a constant heart rate during the period of study, while mean arterial pressure rose continuously. Both levels of hypoxic incubation (15% and 10%O2) resulted in a lower mean arterial pressure at 90% of incubation, while heart rate was lower in the 10%O2 group only. Acute (5 min) exposure to 10%O2 in the normoxic group resulted in a biphasic response, with a normotensive bradycardia occurring during the period of exposure and a hypertensive tachycardic response occurring during recovery. The embryos incubated under hypoxia also showed a blunted response to acute hypoxic stress. In conclusion, the main responses elicited by chronic hypoxic incubation, namely, cardiac enlargement, blunted hypoxic response and systemic vasodilation, may provide chronically hypoxic embryos with a new physiological repertoire for responding to hypoxia.
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| 7. |
- Fallahsharoudi, Amir, 1981-, et al.
(author)
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Changes in pituitary gene expression may underlie multiple domesticated traits in chickens.
- 2019
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In: Heredity. - London : Nature Publishing Group. - 0018-067X .- 1365-2540. ; 122:2, s. 195-204
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Journal article (peer-reviewed)abstract
- Domesticated animals share a unique set of morphological and behavioral traits, jointly referred to as the domesticated phenotype. Striking similarities amongst a range of unrelated domesticated species suggest that similar regulatory mechanisms may underlie the domesticated phenotype. These include color pattern, growth, reproduction, development and stress response. Although previous studies have focused on the brain to find mechanisms underlying domestication, the potential role of the pituitary gland as a target of domestication is highly overlooked. Here, we study gene expression in the pituitary gland of the domesticated White Leghorn chicken and its wild ancestor, the Red Junglefowl. By overlapping differentially expressed genes with a previously published list of functionally important genes in the pituitary gland, we narrowed down to 34 genes. Amongst them, expression levels of genes with inhibitory function on pigmentation (ASIP), main stimulators of metabolism and sexual maturity (TSHB and DIO2), and a potential inhibitor of broodiness (PRLR), were higher in the domesticated breed. Additionally, expression of 2 key inhibitors of the stress response (NR3C1, CRHR2) was higher in the domesticated breed. We suggest that changes in the transcription of important modulatory genes in the pituitary gland can account not only for domestication of the stress response in domestic chickens, but also for changes in pigmentation, development, and reproduction. Given the pivotal role of the pituitary gland in the regulation of multiple shared domesticated traits, we suggest that similar changes in pituitary transcriptome may contribute to the domesticated phenotype in other species as well.
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| 8. |
- Farrell, Anthony P., et al.
(author)
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Maximum cardiac performance and adrenergic sensitivity of the sea bass Dicentrarchus labrax at high temperatures
- 2007
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In: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 210, s. 1216-1224
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Journal article (peer-reviewed)abstract
- We examined maximum cardiac performance of sea bass Dicentrarchus labrax acclimated to 18°C and 22°C, temperatures near the optimum for growth of this species. Our aim was to study whether cardiac performance, especially the effect of adrenergic stimulation, differed when compared to salmonids. Sea bass and salmonids are both athletic swimmers but their cardiac anatomy differs markedly. The sea bass ventricle does not receive any oxygenated blood via a coronary circulation while salmonids have a well-developed arterial supply of oxygen to the compact layer of the ventricle. Using in situ perfused heart preparations, maximum cardiac performance of 18°C-acclimated sea bass (i.e. cardiac output=90.8± 6.6 ml min–1 kg–1 and power output=11.41±0.83 mW g–1) was found to be comparable to that previously reported for rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta at similar temperatures and with tonic adrenergic (5 nmol l–1 adrenaline) stimulation. For 22°C-acclimated sea bass, heart rate was significantly higher, but maximum stroke volume was reduced by 22% (1.05±0.05 ml kg–1) compared with 18°C (1.38± 0.11 ml kg–1). As a result, maximum cardiac output (99.4±3.9 ml min–1 kg–1) was not significantly different at 22°C. Instead, maximum power output was 27% higher at 22°C (14.95±0.96 mW g–1) compared with 18°C, primarily because of the smaller relative ventricular mass in 22°C-acclimated sea bass. Compared with tonic adrenergic stimulation with 5 nmol l–1 adrenaline, maximum adrenergic stimulation of the sea bass heart produced only modest stimulatory effects at both temperatures (12–13% and 14–15% increases in maximum cardiac output and power output, respectively, with no chronotropic effect). Adrenergic stimulation also increased the cardiac sensitivity to filling pressure, with the maximum left-shift in the Starling curve being produced by 50–100 nmol l–1 adrenaline at 18°C and 10–50 nmol l–1 adrenaline at 22°C. We show that the sea bass, which lacks a coronary arterial oxygen supply to the ventricle, has a powerful heart. Its maximum performance is comparable to a salmonid heart, as is the modest stimulatory effect of adrenaline at high temperature.
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| 9. |
- Lindholm, Caroline, 1984-
(author)
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Intermittent fasting in chickens : Physiological mechanisms and welfare implications for broiler breeders
- 2019
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Doctoral thesis (other academic/artistic)abstract
- Broiler breeder chickens are the parent stock used to produce broiler chickens raised for human consumption and have long been caught in a welfare dilemma. The immensely successful selection of fast-growing meat-type chickens over the last 80 years has created a remarkably efficient meat-producer and given us access to cheap chicken meat but has also created health problems for the animals. These problems especially affect the breeder generation, which must be raised with strict feed restriction to limit weight gain and thus maintain physical health and normal fertility. At the same time, however, feed restriction causes chronic hunger and feeding frustration with reduced animal welfare as a result. In the EU alone 60 million breeders are affected annually and although the problem is well-known within the industry, there is financial incentive to keep selecting for even higher growth potential in broilers, further increasing the problems for broiler breeders.Many strategies for reducing the impact of growth restriction on breeder welfare have been suggested and are usually aimed at somehow increasing the amount of feed given at feeding times. This can be done either through adding bulky fibers to the diet or by reducing feeding frequency. In this thesis, focus is on the latter as we explore the effects of intermittent fasting (IF) on the welfare of young broiler breeders as well as wild-type Red Junglefowl. Intermittent fasting, or “skip-a-day” feeding, is supposedly the most common feeding strategy for broiler breeders worldwide but is perceived as welfare-reducing and thus illegal in Sweden and several other European countries. In spite of this, the scientific knowledge of how this type of feeding affects chicken welfare is scarce.Assessing the overall effect of IF on breeder welfare is complicated by large variations in both physiological and behavioral parameters between feeding and fasting days, but it does appear that chicken welfare is improved at least on the feeding days of IF regimens. It also seems that some of the health benefits reported from mammalian studies of IF may apply to chickens as well, although behavioral indicators still point to welfare issues unless the level of feed restriction can be relaxed. In comparison with daily feed restriction, IF appears to increase the motivation for feed consumption but to reduce the motivation for appetitive behaviors such as foraging, which may explain why birds fed on this type of schedule are often reported as calmer.
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| 10. |
- Lindholm, Caroline, 1984-, et al.
(author)
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Intermittent fasting induces chronic changes in the hepatic gene expression of Red Jungle Fowl (Gallus gallus)
- 2022
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In: BMC Genomics. - London, United Kingdom : Springer Nature. - 1471-2164. ; 23
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Journal article (peer-reviewed)abstract
- Background: Intermittent fasting (IF), the implementation of fasting periods of at least 12 consecutive hours on a daily to weekly basis, has received a lot of attention in recent years for imparting the life-prolonging and health-promoting effects of caloric restriction with no or only moderate actual restriction of caloric intake. IF is also widely practiced in the rearing of broiler breeders, the parent stock of meat-type chickens, who require strict feed restriction regimens to prevent the serious health problems associated with their intense appetites. Although intermittent fasting has been extensively used in this context to reduce feed competition and its resulting stress, the potential of IF in chickens as an alternative and complementary model to rodents has received less investigation. In both mammals and birds, the liver is a key component of the metabolic response to IF, responding to variations in energy balance. Here we use a microarray analysis to examine the liver transcriptomics of wild-type Red Jungle Fowl chickens fed either ad libitum, chronically restricted to around 70% of ad libitum daily or intermittently fasted (IF) on a 2:1 (2 days fed, 1 day fasted) schedule without actual caloric restriction. As red junglefowl are ancestral to domestic chicken breeds, these data serve as a baseline to which existing and future transcriptomic results from farmed birds such as broiler breeders can be compared.Results: We find large effects of feeding regimen on liver transcriptomics, with most of the affected genes relating to energy metabolism. A cluster analysis shows that IF is associated with large and reciprocal changes in genes related to lipid and carbohydrate metabolism, but also chronic changes in genes related to amino acid metabolism (generally down-regulated) and cell cycle progression (generally up-regulated). The overall transcription pattern appears to be one of promoting high proliferative plasticity in response to fluctuations in available energy substrates. A small number of inflammation-related genes also show chronically changed expression profiles, as does one circadian rhythm gene.Conclusions: The increase in proliferative potential suggested by the gene expression changes reported here indicates that birds and mammals respond similarly to intermittent fasting practices. Our findings therefore suggest that the health benefits of periodic caloric restriction are ubiquitous and not restricted to mammals alone. Whether a common fundamental mechanism, for example involving leptin, underpins these benefits remains to be elucidated.
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