Effect of fasting on glucose turnover in a carnivorous fish (Hoplias sp)

Machado, C. R.; Garófalo, Maria Antonieta Rissato; Roselino, J E S; Kettelhut, Ísis C.; Migliorini, R H

doi:10.1152/ajpregu.1989.256.3.r612

Cited by 15 publications

(11 citation statements)

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“…Several studies have demonstrated that plasma free FA levels increase in fish subjected to fasting regimens (Lewis and Epple, 1984;Machado et al, 1988Machado et al, , 1989Shimeno et al, 1990;Sheridan and Mommsen, 1991;Souza et al, 2000;Figueiredo-Garutti et al, 2002). The elevation in plasma glycerol levels observed in the present study suggest that R. quelen mobilized glycerol from lipid stores (mesenteric, muscle, belly flap, and liver), as has been observed in other fish species (Albalat et al, 2006;Farbridge et al, 1992;Navarro et al, 1992).…”

Section: Experimental Groups I (Control)supporting

confidence: 80%

Protein and lipid metabolism adjustments in silver catfish (Rhamdia quelen) during different periods of fasting and refeeding

et al. 2017

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The fish may experience periods of food deprivation or starvation which produce metabolic changes. In this study, adult Rhamdia quelen males were subjected to fasting periods of 1, 7, 14, and 21 days and of refeeding 2, 4, 6, and 12 days. The results demonstrated that liver protein was depleted after 1 day of fasting, but recovered after 6 days of refeeding. After 14 days of fasting, mobilization in the lipids of the muscular tissue took place, and these reserves began to re-establish themselves after 4 days of refeeding. Plasmatic triglycerides increased after 1 day of fasting, and decreased following 2 days of refeeding. The glycerol in the plasma oscillated constantly during the different periods of fasting and refeeding. Changes in the metabolism of both protein and lipids during these periods can be considered as survival strategies used by R. quelen. The difference in the metabolic profile of the tissues, the influence of the period of fasting, and the type of reserves mobilized were all in evidence.Keywords: fasting, lipids, protein, refeeding, silver catfish. Ajustes no metabolismo de proteínas e lipídios no jundiá (Rhamdia quelen) durante diferentes períodos de jejum e realimentação ResumoOs peixes podem sofrer períodos de privação de alimentos ou de fome, que produzem mudanças metabólicas. Neste estudo, jundiás machos adultos foram submetidos a jejum períodos de 1, 7, 14 e 21 dias e realimentação 2, 4, 6, e 12 dias. Os resultados demonstraram que a proteína do fígado foi esgotada depois de um dia de jejum, mas restabeleceu após 6 dias de realimentação. Após 14 dias de jejum, ocorreu a mobilização dos lípidos no tecido muscular sendo que estas reservas começaram a re-estabelecer-se após 4 dias de realimentação. Os triglicérides plasmáticos aumentam após um dia de jejum, e diminuiram após 2 dias de realimentação. O glicerol no plasma oscilou constantemente durante os diferentes períodos de jejum e realimentação. As alterações no metabolismo de proteína e lipídios durante estes períodos podem ser consideradas uma estratégias de sobrevivência utilizada pelo Rhamdia quelen. Sendo que a diferença no perfil metabólico tecidual bem como a influência do período de jejum e o tipo de reserva a ser mobilizada foram observadas neste estudo.

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Section: Experimental Groups I (Control)supporting

confidence: 80%

Protein and lipid metabolism adjustments in silver catfish (Rhamdia quelen) during different periods of fasting and refeeding

et al. 2017

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“…The true capacity of fish for glucoregulation could be better assessed by quantifying the plasticity of glucose kinetics rather than by relying on concentration changes during glucose tolerance tests. The first glucose fluxes reported for fish were measured by bolus injection of tracer in kelp bass (Paralabrax clathratus) (Bever et al, 1977(Bever et al, , 1981, skipjack tuna (Katsuwonus pelamis) (Weber et al, 1986), seabass (Dicentrarchus labrax) (Garin et al, 1987), wolf fish (Hoplias malabaricus) (Machado et al, 1989) and brown trout (Salmo trutta) (Blasco et al, 1996). These early studies showed that glucose turnover rate can be strongly reduced by prolonged fasting and that resting glucose fluxes vary with the basal metabolic rate of individual species.…”

Section: Glucose Kinetics and Glucoregulationmentioning

confidence: 99%

Metabolic fuel kinetics in fish: swimming, hypoxia and muscle membranes

Weber

Choi

Gonzalez

et al. 2016

Journal of Experimental Biology

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Muscle performance depends on the supply of metabolic fuels and disposal of end-products. Using circulating metabolite concentrations to infer changes in fluxes is highly unreliable because the relationship between these parameters varies greatly with physiological state. Quantifying fuel kinetics directly is therefore crucial to the understanding of muscle metabolism. This review focuses on how carbohydrates, lipids and amino acids are provided to fish muscles during hypoxia and swimming. Both stresses force white muscle to produce lactate at higher rates than it can be processed by aerobic tissues. However, lactate accumulation is minimized because disposal is also strongly stimulated. Exogenous supply shows that trout have a much higher capacity to metabolize lactate than observed during hypoxia or intense swimming. The low density of monocarboxylate transporters and their lack of upregulation with exercise explain the phenomenon of white muscle lactate retention. This tissue operates as a quasi-closed system, where glycogen stores act as an 'energy spring' that alternates between explosive power release during swimming and slow recoil from lactate in situ during recovery. To cope with exogenous glucose, trout can completely suppress hepatic production and boost glucose disposal. Without these responses, glycemia would increase four times faster and reach dangerous levels. The capacity of salmonids for glucoregulation is therefore much better than presently described in the literature. Instead of albumin-bound fatty acids, fish use lipoproteins to shuttle energy from adipose tissue to working muscles during prolonged exercise. Proteins may play an important role in fueling muscle work in fish, but their exact contribution is yet to be established. The membrane pacemaker theory of metabolism accurately predicts general properties of muscle membranes such as unsaturation, but it does not explain allometric patterns of specific fatty acids. Investigations of metabolic fuel kinetics carried out in fish to date have demonstrated that these ectotherms use several unique strategies to orchestrate energy supply to working muscles and to survive hypoxia.

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“…These observations are based on measurements of blood glucose concentrations that depend on changing rates of appearance in and disappearance from the circulation (R a and R d glucose). Earlier kinetics studies have reported baseline glucose fluxes in kelp bass, sea bass and tuna (Bever et al, 1977;Garin et al, 1987;Weber et al, 1986), as well as changes in flux during glucose tolerance tests in wolf fish and brown trout (Blasco et al, 1996;Machado et al, 1989). However, all these studies have relied on the bolus injection technique, which cannot quantify R a and R d separately.…”

Section: Introductionmentioning

confidence: 99%

Pushing the limits of glucose kinetics: how rainbow trout cope with a carbohydrate overload

Choi

Weber

2015

Journal of Experimental Biology

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Rainbow trout are generally considered to be poor glucoregulators. To evaluate this, exogenous glucose was administered to chronically hyperglycemic fish at twice the endogenous rate of hepatic production, and their ability to modulate glucose fluxes was tested. Our goals were to determine: (1) whether hyperglycemic fish maintain higher glucose fluxes than normal; (2) whether they can lower hepatic production (R a glucose) or stimulate disposal (R d glucose) to cope with a carbohydrate overload; and (3) an estimate of the relative importance of glucose as an oxidative fuel. Results show that hyperglycemic trout sustain elevated baseline R a and R d glucose of 10.6±0.1 µmol kg −1 min −1 (or 30% above normal). If 50% of R d glucose was oxidized as in mammals, glucose could account for 36 to 100% of metabolic rate when exogenous glucose is supplied. In response to exogenous glucose, rainbow trout can completely suppress hepatic glucose production and increase disposal 2.6-fold, even with chronically elevated baseline fluxes. Such large changes in fluxes limit the increase in blood glucose to 2.5-fold and are probably mediated by the effects of insulin on glucose transporters 2 and 4 and on key enzymes of carbohydrate metabolism. Without this strong and rapid modulation of glucose kinetics, glycemia would rise four times faster to reach dangerous levels, exceeding 100 mmol l −1. Such responses are typical of mammals, but rather unexpected for an ectotherm. The impressive plasticity of glucose kinetics demonstrated here suggests that trout have a much better glucoregulatory capacity than is usually portrayed in the literature.

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Effect of fasting on glucose turnover in a carnivorous fish (Hoplias sp)

Cited by 15 publications

References 0 publications

Protein and lipid metabolism adjustments in silver catfish (Rhamdia quelen) during different periods of fasting and refeeding

Protein and lipid metabolism adjustments in silver catfish (Rhamdia quelen) during different periods of fasting and refeeding

Metabolic fuel kinetics in fish: swimming, hypoxia and muscle membranes

Pushing the limits of glucose kinetics: how rainbow trout cope with a carbohydrate overload

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