Metabolism and Action of Insulin and Glucagon in Goat during Lactating and Dry Period

Grizard, Jean; Champredon, C.; Aina, E.; Sornet, Claire; Debras, Élisabeth

doi:10.1055/s-2007-1010756

Cited by 13 publications

(8 citation statements)

References 15 publications

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“…Similar increases in rates of insulin clearance have been observed in goats (Grizard et al 1988), cows (Hart, Bines & Morant, 1980) and rats (Jones, Ilic & Williamson, 1984) and may be attributed at least in part to uptake of insulin by the mammary gland. The overall picture that emerges from this study is broadly compatible with observations on individual tissues observed in vitro and in vivo.…”

Section: Discussionsupporting

confidence: 70%

Metabolic responses to euglycaemic hyperinsulinaemia in lactating and non-lactating sheep in vivo

Faulkner¹,

Pollock²

1990

Journal of Endocrinology

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Glucose utilization and production and changes in concentrations of plasma metabolites were studied in lactating and non-lactating sheep in response to three levels of insulin infusion whilst maintaining euglycaemia. Glucose utilization and production responded to insulin infusion similarly in both lactating and non-lactating ewes but, as circulating concentrations of insulin were lower in lactating animals, these parameters appeared more sensitive to plasma concentrations of insulin in lactating sheep. Changes in plasma concentrations of glycerol and free fatty acids during lactation indicated reduced sensitivity to insulin in adipose tissue and changes in plasma concentrations of amino acids were also less during lactation, suggesting reduced sensitivity of protein synthesis to insulin. Changes in plasma concentrations of urea and beta-hydroxybutyrate during lactation were similar to those in non-lactating animals, indicating similar insulin sensitivity of hepatic metabolism. It is concluded that during lactation ovine adipose tissue and muscle are more resistant to increased concentrations of insulin but that the sensitivity of the sheep liver is unchanged or increased. The rate of removal of insulin from the circulation was higher in lactating animals.

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Section: Discussionsupporting

confidence: 70%

Metabolic responses to euglycaemic hyperinsulinaemia in lactating and non-lactating sheep in vivo

Faulkner¹,

Pollock²

1990

Journal of Endocrinology

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“…Lactation is known to be a factor that affects circulating levels of insulin since the clearance rate of insulin increases during lactation in rats (Jones et al 1984) and goats (Grizard et al 1988). Furthermore, previous results suggest that there is a decreased sensitivity in the insulin response to hyperglycaemia during lactation (Faulkner & Martin, 1999).…”

Section: Insulinmentioning

confidence: 99%

Intravenous Magnesium Reduces the Rate of Glucose Disposal in Lactating Sheep

Gow

Mitchell

Wait

2003

Experimental Physiology

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Magnesium deficiency is generally associated with an impaired ability to dispose of glucose. In order to test whether or not increasing the peripheral free Mg concentration ([Mg 2+ ]) would enhance glucose disposal, we have carried out glucose infusions in sheep with and without simultaneous infusion of Mg. Basal plasma glucose levels were higher in lactating sheep ('lactators') than in non-lactating sheep (controls) (P < 0.05). The glucose disposal rate (K G ) with no added Mg was greater in lactators than controls (P < 0.05). When Mg was added to the infusate, K G in lactators was reduced (P < 0.005). Infusion of Mg depressed basal insulin levels in controls and lactators (P < 0.0001 for both). The insulin response to the intravenous glucose tolerance test (IVGTT) was lower in lactators compared with controls (P < 0.0001); however, after correcting for the reduced basal insulin level when Mg was included during the IVGTT, there was no difference between the two groups. We conclude that intravenous Mg at the doses used in this study leads to a decrease in basal insulin secretion, and that increasing serum

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“…Likewise, the maximal responsiveness of gluconeogenesis to glucagon, determined here by the magnitude of maximal glucagon effects within each preincubation group, is increased following chronic glucagon exposure only for propionate, but it is blunted for lactate. In early lactation, circulating glucagon concentrations in goats are elevated compared with the midlactation (Debras et al, 1989) or dry period (Grizard et al, 1988) and this may sensitize goats to the effects of acute pulses in portal glucagon.…”

Section: Propionate Lactatementioning

confidence: 99%

Chronic and transitional regulation of gluconeogenesis and glyconeogenesis by insulin and glucagon in neonatal calf hepatocytes.

Donkin

Bertics

Armentano

1997

Journal of Animal Science

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Milk-fed calves were used as a source of hepatocytes to establish monlayers to test the effects of chronic (41 h) incubation with no hormone, 100 nM insulin, or 100 nM glucagon on gluconeogenesis (glucose retained as glycogen plus glucose released into the medium) from 2.5 mM [2-(14)C]propionate and 2.0 mM [U-14C]lactate (1.0 mM lactate plus 1.0 mM pyruvate) during a subsequent 3-h (acute) incubation. Media for acute incubations contained no hormone, 0 or 10 nM insulin, or 0, 1, 10, or 100 mM glucagon. Chronic glucagon increased gluconeogenesis from propionate and glyconeogenesis from propionate and lactate compared with chronic exposure to medium with no hormone. A chronic glucagon x acute hormone interaction was manifested as an augmented response to acute glucagon on gluconeogenesis from propionate; a similar potentiation was not evident for gluconeogenesis from lactate. The concentration of glucagon required to acutely stimulate gluconeogenesis was increased by prior incubation with glucagon. Acute glucagon decreased the flux of glucose retained as glycogen regardless of chronic hormone treatment. Chronic incubation with insulin diminished the stimulatory effects of glucagon on gluconeogenesis from lactate. Chronic incubation with insulin did not alter the sensitivity or responsiveness at acute glucagon of gluconeogenesis from propionate. The data demonstrate persisting changes that favor increased basal gluconeogenesis from propionate with chronically elevated glucagon coupled to an increased capacity to respond acutely to glucagon and opposing chronic actions of insulin on lactate metabolism. These data suggest that insulin and glucagon target separate pathways that are unique to metabolism of propionate and lactate.

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Metabolism and Action of Insulin and Glucagon in Goat during Lactating and Dry Period

Cited by 13 publications

References 15 publications

Metabolic responses to euglycaemic hyperinsulinaemia in lactating and non-lactating sheep in vivo

Metabolic responses to euglycaemic hyperinsulinaemia in lactating and non-lactating sheep in vivo

Intravenous Magnesium Reduces the Rate of Glucose Disposal in Lactating Sheep

Chronic and transitional regulation of gluconeogenesis and glyconeogenesis by insulin and glucagon in neonatal calf hepatocytes.

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