Glucagon in the Fetus and the Newborn

Girard, Jean; Sperling, Mark A.

doi:10.1007/978-3-642-69019-8_14

Cited by 13 publications

(19 citation statements)

References 84 publications

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“…During the immediate postnatal period, plasma glucagon increases and plasma insulin decreases or remains very low (8,24). In newborn rats, transient neonatal hypoglycemia is observed, which many authors consider to be the factor that triggers glucagon secretion in these animals (24,43,66).…”

Section: Discussionmentioning

confidence: 99%

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Expression of genes participating in regulation of fatty acid and glucose utilization and energy metabolism in developing rat hearts

Lavrentyev

Cook

2004

American Journal of Physiology-Heart and Circulatory Physiology

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Lavrentyev, Eduard N., Daifen He, and George A. Cook. Expression of genes participating in regulation of fatty acid and glucose utilization and energy metabolism in developing rat hearts. Am J Physiol Heart Circ Physiol 287: H2035-H2042, 2004. First published June 24, 2004 doi:10.1152/ajpheart.00372.2004.-The heart is a unique organ that can use several fuels for energy production. During development, the heart undergoes changes in fuel supply, and it must be able to respond to these changes. We have examined changes in the expression of several genes that regulate fuel transport and metabolism in rat hearts during early development. At birth, there was increased expression of fatty acid transporters and enzymes of fatty acid metabolism that allow fatty acids to become the major source of energy for cardiac muscle during the first 2 wk of life. At the same time, expression of genes that control glucose transport and oxidation was downregulated. After 2 wk, expression of genes for glucose uptake and oxidation was increased, and expression of genes for fatty acid uptake and utilization was decreased. Expression of carnitine palmitoyltransferase I (CPT I) isoforms during development was different from published data obtained from rabbit hearts. CPT I␣ and I␤ isoforms were both highly expressed in hearts before birth, and both increased further at birth. Only after the second week did CPT I␣ expression decrease appreciably below the level of CPT I␤ expression. These results represent another example of different expression patterns of CPT I isoforms among various mammalian species. In rats, changes in gene expression followed nutrient availability during development and may render cardiac fatty acid oxidation less sensitive to factors that influence malonyl-CoA content (e.g., fluctuations in glucose concentration) and thereby favor fatty acid oxidation as an energy source for cardiomyocytes in early development. carnitine palmitoyltransferase; oxidation; translocase; acetyl-CoA

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Section: Discussionmentioning

confidence: 99%

“…In newborn rats, transient neonatal hypoglycemia is observed, which many authors consider to be the factor that triggers glucagon secretion in these animals (24,43,66). The large liver glycogen stores accumulated during pregnancy are rapidly mobilized and are exhausted 12 h after delivery (3,57).…”

Section: Discussionmentioning

confidence: 99%

Expression of genes participating in regulation of fatty acid and glucose utilization and energy metabolism in developing rat hearts

Lavrentyev

Cook

2004

American Journal of Physiology-Heart and Circulatory Physiology

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“…Therefore, our results were supported by those of Imaizumi et al [16] who found that the plasma concentration of apo E was lower in adults than in suckling rats. The time course of the apo-E mRNA level in rat liver was paralleled with dramatic changes in plasma levels of glucagon and insulin (Table 1) [29,301. Glucagon level rose during the first hours of life and, during the suckling period, remained at a level 3 -6-fold higher than in adults.…”

Section: Time Course O J U P -E M R N a Expression In Rut Liver Durinmentioning

confidence: 98%

Apolipoprotein‐E‐gene expression in rat liver during development in relation to insulin and glucagon

Mangeney¹,

Cardot²,

Lyonnet³

et al. 1989

European Journal of Biochemistry

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An apolipoprotein-E (apo-E) cDNA probe, cloned by immunoscreening of a l G T l l rat liver cDNA library, was used to further characterize the expression of the apo-E gene in rat liver during development, in relation to plasma insulin and glucagon levels. The apo-E mRNA level was low in fetus liver, then abruptly increased at birth and rose further during the suckling period. It returned to the level at birth in 10-week-old adults. These variations were paralleled with dramatic changes in plasma glucagon, which rose at birth and remained high during suckling. At the same time, the insulin/glucagon molar ratio fell.Administration of N6,02-dibutyryl CAMP to 5-day-old rats resulted in a significant induction of liver apo-E mRNA. Moreover, liver apo-E mRNA rose in 10-h-fasted suckling rats as compared to controls, while plasma glucagon increased and the insulin/glucagon ratio decreased. Conversely, glucose feeding of suckling rats did not induce any increase in liver apo-E mRNA, the insulin/glucagon ratio was 10-fold higher than in fasted animals.Our results are consistent with liver apo-E gene expression being under the control of plasma glucagon and of the glucagon/insulin balance. Apo E is a major protein component of lipoproteins [l]. It is responsible for mediating the interaction of specific lipoproteins with extrahepatic and hepatic apo-B/E receptors and the hepatic apo-E receptors [l, 21.The complete sequence of apo-E cDNA, and the structure of its gene, have been reported for rats and humans [3 -61. Apo-E gene expression has been found at a substantial level in brain, adrenals and other peripheral tissues in rats, rabbits, primates and humans [7 -111. Nevertheless, apo E is mainly synthesized in the liver and represents about 1 YO of the total liver mRNA [12]. However, little information is available on the regulation of apo-E-gene expression.

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“…This rapid change of the insulin/glucagon molar ratio at birth is far from being fully explained by the metabolic changes occur ring in the early postnatal period [review in 43]. More likely, the dramatic fall in insulin and the acute rise in plasma glucagon at birth are related to adrenergic stimulation due to the stress accompanying birth [40].…”

Section: Insulin and Glucagon In The Fetus At Term And The Newbornmentioning

confidence: 99%

Insulin and Glucagon during the Perinatal Period: Secretion and Metabolic Effects on the Liver

et al. 1985

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Insulin and glucagon are detected in the plasma of most species early in gestation. In the fetus at term, insulin and glucagon secretion can be modified by long-term changes in glucose concentration but the responsiveness of A and B cells to glucose is lower than in the adult. The plasma insulin/glucagon molar ratio is high in the fetus at term, then decreases dramatically immediately after birth and remains low during the first hours of extrauterine life. This situation results in favored hepatic glycogen storage and prevented gluconeogenesis in utero, and sharp glycogen breakdown and active gluconeogenesis during the early postnatal period.

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Glucagon in the Fetus and the Newborn

Cited by 13 publications

References 84 publications

Expression of genes participating in regulation of fatty acid and glucose utilization and energy metabolism in developing rat hearts

Expression of genes participating in regulation of fatty acid and glucose utilization and energy metabolism in developing rat hearts

Apolipoprotein‐E‐gene expression in rat liver during development in relation to insulin and glucagon

Insulin and Glucagon during the Perinatal Period: Secretion and Metabolic Effects on the Liver

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