Glucagon control of glycogenolysis in catfish tissues

Ottolenghi, C; Ac, Puviani; Baruffaldi, A.; Me, Gavioli; Brighenti, L

doi:10.1016/0305-0491(88)90074-0

Cited by 11 publications

(12 citation statements)

References 24 publications

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“…Even though the animals used in this study are 6-8 months starved (a condition experienced in nature by eels) these values are consistent with other liver GPase studies in catfish (Umminger and Benziger 1975;Ottolenghi et al 1986Ottolenghi et al , 1988, goldfish (Storey 1988) and rat (e.g. Schwartz and Rall 1973;Stalman and Hers 1975;Katz et al 1979).…”

Section: Discussionsupporting

confidence: 74%

“…The inositol-P mechanism in the rat liver takes precedence at low hormone concentrations (10-10 to 10-8 M). The contrasting effects of glucagon found in this study compared to previous studies where significant effects of glucagon on GPase were noted (Umminger and Benziger 1975;Vernier and Sire 1978;Ottolenghi et al 1988) may be related to the lower concentration of hormone employed in our study (10-8 M), where inositol-P may be the second messenger. In fact, we found that anglerfish glucagon did not increase hepatocyte cAMP content at concentrations below 10 -7 M, whereas significant effects of the hormone on glucose production were apparent at hormone concentrations as low as 10 -9 M. Similar concentration-dependent effects on glycogenolysis have been found in goldfish, Carassius auratus, hepatocytes (Birnbaum et al 1976).…”

Section: Discussioncontrasting

confidence: 56%

“…Glucagon stimulates liver GPase activities in catfish (Umminger and Benziger 1975;Ottolenghi et al 1988), trout (Vernier and Sire 1978), and killifish , and this is associated with a decrease in glycogen content in catfish liver pieces or slices (Umminger and Benziger 1975;Ottolenghi et al 1988). Glycogen content is also decreased by bovine glucagon in hepatocytes of the sea raven (Foster and Moon 1987) and the American eel this study).…”

Section: Discussionmentioning

confidence: 72%

“…Intered in the liver of trout (Salmo gairdneri : Vernier and Sire 1978), catfish (Ictalurus sp. : Ottolenghi et al 1986Ottolenghi et al , 1988, killifish (Fundulus heteroclitus: Umminger and Benziger 1975;, and salmon (Oncorhynchus tshawytcha, 0. kisutch: Plisetskaya et al 1989). Epinephrine, however, did not alter GPase activities in the liver of the carp (Cyprinus carpio) (Demael-Suard and Garin 1970), a fish that contains an amylase with activities exceeding that of GPase (Murat 1976;Pikucans and Umminger 1979).…”

Section: Introductionmentioning

confidence: 99%

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The role of glycogen phosphorylase in the regulation of glycogenolysis by insulin and glucagon in isolated eel (Anguilla rostrata) hepatocytes

Foster

Moon

1990

Fish Physiol Biochem

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The effects of porcine, scombroid, and salmon insulins, and bovine and anglerfish glucagons on glycogen depletion and glycogen phosphorylase (GPase) activities were examined in freshly isolated American eel (Anguilla rostrata) hepatocytes. Eel liver GPase in crude homogenates was activated (increase in % GPase a) by phosphorylating conditions and was rapidly inactivated (less than 1 h) when a phosphatase inhibitor (fluoride) was absent. Caffeine inhibits, and AMP activates, the b form of GPase consistent with their effects on rat liver GPase. Both mammalian and fish glucagons increased glucose production in eel hepatocytes, but had more ambiguous effects on glycogen levels and GPase activities. The magnitude of bovine glucagon effects were dependent on the initial glycogen content of the cells; only at glycogen concentrations less than approximately 70 μmoles.g(-1) did glucagon significantly increase % GPase a. Anglerfish glucagon significantly increased cyclic AMP (cAMP) concentrations by 90% at 10(-7) M, but had no effects at 10(-9) M and 10(-8) M. Scombroid and salmon insulins maintained hepatocyte glycogen concentrations and decreased glucose production, with these effects more pronounced at low (10(-9) to 10(-8) M) rather than high (10(-7) M) hormone concentrations. Porcine and salmon insulins decreased total GPase and % GPase a activities, and salmon insulin decreased CAMP levels, but only at 10(-8) M (by 44%).Glycogen is, therefore, depleted by glucagon and maintained by insulin in freshly isolated American eel hepatocytes, and these changes are accomplished, at least in part, by changes in the activities of GPase. Changes in cAMP do not explain all of the observed hormone effects.

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Section: Discussionsupporting

confidence: 74%

Section: Discussioncontrasting

confidence: 56%

Section: Discussionmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 99%

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The role of glycogen phosphorylase in the regulation of glycogenolysis by insulin and glucagon in isolated eel (Anguilla rostrata) hepatocytes

Foster

Moon

1990

Fish Physiol Biochem

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“…In fish, however, there is no clear indication of an interdependence between insulin and glucagon secretion (Plisetskaya 1990). Several studies have, however, suggested a participating effect of glucagon in energy fluxes through glycogenolysis, lipolysis as well as gluconeogenesis (Umminger and Benziger 1975;Murat and Plisetskaya 1977;Plisetskaya et al 1986;Suarez and Mommsen 1987;Ottolenghi et al 1988;Mommsen and Moon 1989). The high levels of plasma FAA in the present experiment may have contributed to the high levels of glucagon before fasting.…”

contrasting

confidence: 56%

Dietary carbohydrate utilization in cod (Gadus morhua): metabolic responses to feeding and fasting

Hemre

Lie

Sundby³

1993

Fish Physiol Biochem

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Moist diets with increasing amounts of carbohydrate (0.5%, 10% and 21% on a dry weight basis) were each fed to duplicate groups of cod (initial weight 370 g) for 8 weeks, after which all groups were fasted for 4 weeks. Protein energy was high and accounted for more than 70% of the gross energy content in all feeds, and the diets were maintained isocaloric by substituting lipid energy for carbohydrate energy. No indigestible binder was added. Excellent growth and feed conversion were obtained in all groups. After 4 weeks of fasting, fish previously fed diets with either 10% or 21% carbohydrate showed significantly higher weight loss than fish fed the diet without carbohydrate. Liver glycogen reached 10% of liver wet weight in fish fed diets containing 10% or 21% carbohydrate and 5% in fish receiving 0.5% carbohydrate after 8 weeks. Following 4 weeks of fasting, liver glycogen was reduced to similar levels in all fish. Plasma glucose levels 4 h after feeding were higher in fish fed the diets with 10% or 21% carbohydrate and plasma free amino acid levels (FAA) were lower, than in fish fed the diet containing 0.5% carbohydrate. Blood lactate concentrations were unaffected during the first 24 h after feeding. After 4 weeks of food deprivation, the levels were significantly reduced only in the 21% carbohydrate group. A link between glucagon and protein metabolism is suggested because plasma glucagon concentration followed the same pattern as the concentrations of plasma FAA throughout the study. Insulin and glucagon-like peptide (GLP) showed a covariation throughout the experiment. Reduced plasma insulin levels were seen after fasting concomitant with reduction in the levels of FAA and glucose. It is suggested that insulin secretion in cod is affected both by plasma FAA and glucose and that cod meets food deprivation by slowing down metabolism.

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Interactive effects of high stocking density and triiodothyronine‐administration on aspects of the in vivo intermediary metabolism and in vitro hepatic response to catecholamine and pancreatic hormone stimulation in brook charr, Salvelinus fontinalis

1992

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Brook charr (Salvelinus fontinalis) were maintained at one of two stocking densities (SD) (30 or 120 kg/m3) and fed either a control or a T3-supplemented (20 mg/kg) diet for 30 days in order to investigate possible interactive effects of SD and T3-administration on growth, feeding rate, food conversion efficiency, and hepatic and dark muscle enzyme activity. In addition, liver slices were incubated in vitro for 6 h with epinephrine, norepinephrine, isoproterenol, propranolol, insulin, glucagon, or somatostatin to evaluate possible SD-T3 interactive effects on hepatic responses to hormonal stimulation. Maintaining the fish at high SD appeared to increase the clearance rate of T3 from the T3-supplemented group. There was no clear evidence of SD-T3 interactive effects on growth rate, feeding rate, or food conversion efficiency, although T3-administration decreased food conversion efficiency, and high SD decreased growth and feeding rates. Of the hepatic enzymes studied, HOAD, malic enzyme, G6PDH, CS, PFK, HK, and GDH activities all showed changes suggestive of interactive SD-T3 effects. Although hepatic FBPase was stimulated by both high SD and T3-administration, there was no evidence of interactive SD-T3 effects. Dark muscle HOAD, CS, and PFK also showed SD-T3-related responses; dark muscle malic enzyme, G6PDH, HK, and GDH were unaffected by either altered SD or T3-administration. Prior treatment of the fish with T3 and high SD had significant effects on free fatty acid (ffa) release to the medium and on hepatic lipid content, but had no effect on the responses to the various endocrine agents used. Glucose release from liver slices of fish stocked at high density (both T3-supplemented and controls) was higher than that of the fish stocked at low density; with the exception of insulin and glucagon, glucose release was similar in all pre-treatment groups. The insulin- and glucagon-stimulated changes in glucose release seen in the fish fed non-supplemented diets were not found in the two groups of fish fed the T3-supplemented diets. High SD and/or T3-administration induced significant lowering of hepatic glycogen content, but there was no effect of pre-treatment on the response to any of the endocrine agents used. The data show a marked effect of SD on energy partitioning processes in brook charr and the animal's ability to respond to T3-stimulation, but provided no evidence of such effects on the liver response to the various agents used.

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Glucagon control of glycogenolysis in catfish tissues

Cited by 11 publications

References 24 publications

The role of glycogen phosphorylase in the regulation of glycogenolysis by insulin and glucagon in isolated eel (Anguilla rostrata) hepatocytes

The role of glycogen phosphorylase in the regulation of glycogenolysis by insulin and glucagon in isolated eel (Anguilla rostrata) hepatocytes

Dietary carbohydrate utilization in cod (Gadus morhua): metabolic responses to feeding and fasting

Interactive effects of high stocking density and triiodothyronine‐administration on aspects of the in vivo intermediary metabolism and in vitro hepatic response to catecholamine and pancreatic hormone stimulation in brook charr, Salvelinus fontinalis

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