Insulin and glucagon family peptides in relation to activities of hepatic hexokinase and other enzymes in fed and starved Atlantic salmon (Salmo salar) and cod (Gadus morhua)

Sundby, Anne; Hemre, Gro‐Ingunn; Borrebæk, Borgar; Christophersen, Berit; Blom, Anne Kristine

doi:10.1016/0305-0491(91)90205-r

Cited by 32 publications

(29 citation statements)

References 20 publications

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“…The major result obtained in trout infused with insulin and fed the high-carbohydrate diet was an absence in glycemic changes when plasma values were compared with the saline-infused control group. These results are surprising, since in other studies where insulin was administrated to fish fed similar diets, significant hypoglycemia was observed with respect to the saline-infused control group (23,41). However, in both studies, the insulin dose was higher and acutely administrated in contrast to the present study in which physiological insulin doses (19) were infused over a longer time period.…”

Section: Discussioncontrasting

confidence: 97%

Glucose homeostasis in rainbow trout fed a high-carbohydrate diet: metformin and insulin interact in a tissue-dependent manner

Polakof

Moon

Aguirre

et al. 2011

American Journal of Physiology-Regulatory, Integrative and Comp

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Polakof S, Moon TW, Aguirre P, Skiba-Cassy S, Panserat S. Glucose homeostasis in rainbow trout fed a high-carbohydrate diet: metformin and insulin interact in a tissue-dependent manner. Am J Physiol Regul Integr Comp Physiol 300: R166 -R174, 2011. First published November 10, 2010; doi:10.1152/ajpregu.00619.2010.-Carnivorous fish species such as the rainbow trout (Oncorhynchus mykiss) are considered to be "glucose intolerant" because of the prolonged hyperglycemia experienced after intake of a carbohydrateenriched meal. In the present study, we use this species to study glucose homeostasis in fish chronically infused with the hypoglycemic agents, insulin, and metformin, and fed with a high proportion of carbohydrates (30%). We analyzed liver, skeletal muscle, and white adipose tissue (WAT), which are insulin-and metformin-specific targets at both the biochemical and molecular levels. Trout infused with the combination of insulin and metformin can effectively utilize dietary glucose at the liver, resulting in lowered glycemia, increased insulin sensitivity, and glucose storage capacity, combined with reduced glucose output. However, in both WAT and skeletal muscle, we observed decreased insulin sensitivity with the combined insulin ϩ metformin treatment, resulting in the absence of changes at the metabolic level in the skeletal muscle and an increased potential for glucose uptake and storage in the WAT. Thus, the poor utilization by rainbow trout of a diet with a high proportion of carbohydrate can at least be partially improved by a combined treatment with insulin and metformin, and the glucose intolerance observed in this species could be, in part, due to some of the downstream components of the insulin and metformin signaling pathways. However, the predominant effects of metformin treatment on the action of insulin in these three tissues thought to be involved in glucose homeostasis remain exclusive in this species.fish; glucose homeostasis; muscle; liver; white adipose tissue; insulin; metformin COMMERCIAL AQUACULTURE OF most carnivorous fish species requires feeding these species a high-protein diet that currently is met with fish meal-based diets. The sustainability of this practice, which requires high quantities of wild fish is accepted today but not for the long term. Thus, it is recognized that the replacement of fish meal with plant raw materials represents a sustainable alternative for the stability and further expansion of aquaculture. However, such substitution remains problematic since feedstuffs of plant origin are naturally rich in carbohydrates, and species like the rainbow trout Oncorhynchus mykiss are considered to be "glucose intolerant" (21, 42) due mainly to the prolonged hyperglycemia experienced after a glucose load or intake of a carbohydrate-enriched meal (3, 24). This intolerance is not thought to be related to the absence of insulin, but, nonetheless, the mechanism(s) by which insulin regulates plasma glucose levels in fish remain speculative, and the relative contribution of the main...

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Section: Discussioncontrasting

confidence: 97%

Glucose homeostasis in rainbow trout fed a high-carbohydrate diet: metformin and insulin interact in a tissue-dependent manner

Polakof

Moon

Aguirre

et al. 2011

American Journal of Physiology-Regulatory, Integrative and Comp

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“…These results are similar to those found by Sundby et al in Atlantic salmon fed with a diet containing 19% carbohydrates and receiving a single insulin administration (Sundby et al, 1991c), even though plasma insulin (exogenous) levels were higher than in the present study. Other studies reported similar results, but comparisons are often difficult as the diets used contained a lower carbohydrate content (~5%), or the insulin dose was pharmacological and the animal model different (omnivorous species) (Ottolenghi et al, 1982).…”

Section: Insulin Improves Glycemia After Feeding One High-carbohydratsupporting

confidence: 93%

Effects of insulin infusion on glucose homeostasis and glucose metabolism in rainbow trout fed a high-carbohydrate diet

Polakof

Moon

Aguirre

et al. 2010

Journal of Experimental Biology

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SUMMARYThe origin for the poor glucose utilization in carnivorous fish species fed high carbohydrate diets remains under debate. In the present study, we have fed rainbow trout a diet containing 30% carbohydrate for 1 or 5 days. In both cases, fish were implanted with mini-osmotic pumps releasing 0.7i.u.kg -1 day -1 bovine insulin, and mRNA transcripts and the protein phosphorylation status of proteins controlling glycemia and glucose-related metabolism were studied in fish killed 6h after the last meal. We demonstrate that when the exposure occurs over a short term (30h), insulin exerts beneficial actions on trout glucose homeostasis, including a lowered glycemia and increased hepatic lipogenic and glycogenic potentials. However, when trout were fed for 5 days, these beneficial actions of insulin infusion were no longer observed. Thus, the increased lipogenic potential observed after one single meal was not present, and this together with the increased glycogenesis and the decreased glucose exported to the blood from the liver explains the lack of hypoglycemic action of insulin. The fact that insulin improved glucose homeostasis when administrated over a short time period implies that endogenous insulin secretion is inadequate in trout to deal with this amount of dietary carbohydrates. Moreover, the fact that a longer exposure to insulin resulted in a reduced response indicates that the rainbow trout is sensitive to insulin, re-enforcing the hypothesis that the hyperglycemia observed following a high carbohydrate meal is an insulin secretion issue rather an insulin action issue.Key words: insulin, fish, dietary carbohydrate, glucose utilization, glucose metabolism. THE JOURNAL OF EXPERIMENTAL BIOLOGY 4152related to a problem of either insulin secretion or insulin action. Therefore, the objectives of the present study on the carnivorous rainbow trout were: (1) to study the metabolic effects of continuous exogenous insulin infusion in fish fed with a high carbohydrate diet for one (test meal) or 5 days; and (2) to evaluate the ability of insulin to improve trout glycemic control when fed with a high carbohydrate diet. In addition, for the first time the three main insulin targets, skeletal muscle, white adipose tissue (WAT) and liver, were studied at both the biochemical and the molecular levels to analyze the potential molecular origins of the plasma glucose profiles observed in fish fed with a high carbohydrate diet. Thus, glycemia, glycogen levels and the mRNA levels of the main proteins involved in glucose metabolism were studied in liver, skeletal muscle and WAT. MATERIALS AND METHODS FishImmature rainbow trout (Oncorhynchus mykiss Walbaum) were obtained from the INRA experimental fish farm facilities of Donzacq (Landes, France). Fish were maintained in tanks kept in open circuits with 17°C well-aerated water and a controlled photoperiod (light:dark 12h:12h), and were fed with a standard trout commercial diet during the acclimation period (T-3P classic, Trouw, France). Experimental protocolsFor susta...

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“…The decreased activity observed in fasted fish is in contrast to the absence of changes reported in liver of food-deprived rainbow trout in another experiment (13), and with the increase noted in Atlantic salmon (37), though a decrease was also observed in liver of fasted cod (37) and gilthead sea bream (24).…”

Section: Influence Of Feeding Conditionscontrasting

confidence: 71%

“…Considering that HK activity is nutritionally regulated in fish liver (6,21,37), it is not surprising that fasting and refeeding altered HK activities in liver similar to changes noted for GK. The decreased activity observed in fasted fish is in contrast to the absence of changes reported in liver of food-deprived rainbow trout in another experiment (13), and with the increase noted in Atlantic salmon (37), though a decrease was also observed in liver of fasted cod (37) and gilthead sea bream (24).…”

Section: Influence Of Feeding Conditionsmentioning

confidence: 90%

Glucokinase and hexokinase expression and activities in rainbow trout tissues: changes with food deprivation and refeeding

Soengas¹,

Polakof²,

Chen³

et al. 2006

American Journal of Physiology-Regulatory, Integrative and Comp

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Insulin and glucagon family peptides in relation to activities of hepatic hexokinase and other enzymes in fed and starved Atlantic salmon (Salmo salar) and cod (Gadus morhua)

Cited by 32 publications

References 20 publications

Glucose homeostasis in rainbow trout fed a high-carbohydrate diet: metformin and insulin interact in a tissue-dependent manner

Glucose homeostasis in rainbow trout fed a high-carbohydrate diet: metformin and insulin interact in a tissue-dependent manner

Effects of insulin infusion on glucose homeostasis and glucose metabolism in rainbow trout fed a high-carbohydrate diet

Glucokinase and hexokinase expression and activities in rainbow trout tissues: changes with food deprivation and refeeding

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