Maturation of Glucose-Stimulated Insulin Secretion in Fetal Sheep

Aldoretta, Peter W.; Carver, Thomas D; Hay, William W.

doi:10.1159/000014000

Cited by 61 publications

(58 citation statements)

References 39 publications

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“…Compared with adult plasma, fetal plasma has been found to contain little proinsulin during late gestation, although both intact and split proinsulin are present in cord plasma from human infants at birth (Godfrey et al 1996). In sheep, the pancreatic cells become progressively more responsive towards term and are very sensitive to changes in glycaemia in the immediate neonatal period (Phillips et al 1981, Aldoretta et al 1998. Similarly, in horses, there are increases in pancreatic cell sensitivity to glucose during late gestation and, again, between birth and 7 days of postnatal age (Fowden et al 1980(Fowden et al , 1982.…”

Section: Introductionmentioning

confidence: 99%

Development of insulin and proinsulin secretion in newborn pony foals

Holdstock

Allen²,

Bloomfield³

et al. 2004

Journal of Endocrinology

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At birth, the endocrine pancreas must assume a glucoregulatory role if the neonate is to survive the transition from parenteral to enteral nutrition. In species like the horse, neonatal hypoglycaemia is common, which suggests that the glucoregulatory mechanisms are not always fully competent at birth. Hence, this study examined pancreatic cell function in newborn foals during nutritional adaptation over the first 10 days post partum. Over a 48 h period at three time intervals after birth (days 1-2, 5-6 and 9-10 post partum), the cell responses to suckling and to intravenous administration of glucose, arginine and saline were measured in seven normal pony foals. Basal plasma concentrations of proinsulin, but not insulin or glucose, increased significantly between days 1 and 10. Suckling caused a gradual increase in plasma glucose, which was accompanied by a significant increase in plasma insulin concentrations 15 min after the onset of suckling on days 5 and 9, but not day 1. There was no significant change in plasma proinsulin concentrations in response to suckling at any age. At all ages studied, glucose and arginine administration stimulated an increase in the plasma concentrations of insulin and proinsulin; these cell responses did not change significantly with postnatal age. The insulin responses to glucose were significantly greater than those of arginine at each time period. Glucose clearance was significantly slower on day 1 than subsequently. Proinsulin and glucose, but not insulin, concentrations decreased significantly after saline administration at all three ages. At each time period, there was a significant positive relationship between the plasma insulin and proinsulin concentrations, the slope of which was significantly shallower on days 1-2 than subsequently. These results show that equine cells are responsive to glucose and arginine and release both insulin and proinsulin during the immediate postnatal period. They also suggest that newborn foals may be insulin resistant on the first day after birth.

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Section: Introductionmentioning

confidence: 99%

Development of insulin and proinsulin secretion in newborn pony foals

Holdstock

Allen²,

Bloomfield³

et al. 2004

Journal of Endocrinology

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“…Ornithine and arginine are two important amino acids that influence insulin and growth hormone secretion in the intestine. 6 Pancreatic insulin secretion in the fetus starts around the second trimester, 7 and we believe that the amniotic fluid glucose and the above mentioned amino acids have an important function in regulating fetal insulin levels through the modulation of incretin peptides. 8 Insulin influences fetal anabolism and growth as described earlier.…”

Section: Discussionmentioning

confidence: 99%

The role of amniotic fluid in influencing neonatal birth weight

Burjonrappa

Crete²,

Bouchard³

2009

J Perinatol

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Objective: We studied 123 neonates with atresias of the gastrointestinal tract at different levels to assess the role of amniotic fluid in the growth and development of the gastrointestinal tract. Our hypothesis was that significant differences in birth weight between groups otherwise comparable would suggest an intrauterine nutritive role for amniotic fluid. Our second hypothesis was that there is a trophic role of amniotic fluid on intestinal epithelium affecting its functional maturity. Establishing earlier tolerance of enteral nutrition in neonates with distal as compared with proximal atresias would support this hypothesis.Study Design: Overall, 123 neonates from a single institution, with duodenal atresia (DA), jejuno-ileal (JIA) and colonic atresia (CA), were separated into three groups. Birth weight, gestational age, associated anomalies and duration of total parenteral nutrition intake were recorded. Neonates with multiple atresias and gastroschisis were excluded from analysis. Statistical analysis of differences between groups was carried out using analysis of variance (ANOVA) for independent samples. Post-ANOVA pairwise comparisons were carried out using the Tukey-HSD test. The Tukey-HSD test showed that DA

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“…In fetal sheep, insulin is released in response to glucose from as early as 70 days (50% gestation) although the magnitude of the response is smaller in mid than late gestation (Fiser et al 1974, Aldoretta et al 1998. Similarly in rats, glucose stimulates insulin output from cultured fetal pancreas or specific cells from mid gestation (Girard et al 1974).…”

Section: Discussionmentioning

confidence: 99%

“…In fetal sheep, there are increases in pancreatic -cell sensitivity to glucose and arginine between mid and late gestation (Fowden 1980a, Aldoretta et al 1998. Similarly, in an earlier study of six fetal horses between mid and late gestation, exogenous glucose only stimulated insulin secretion in the three animals closest to term (Fowden et al 1980).…”

Section: Introductionmentioning

confidence: 90%

“…The endocrine pancreas is functional before birth and secretes insulin in utero in response to glucose and amino acids in several species including the horse (Gersch et al 1974, Fowden 1980a,b, 1982a,b, Bassett et al 1982, Carver et al 1996, Gresores et al 1997, Aldoretta et al 1998. Fetal pancreatic cells also respond to neural stimulation and to circulating catecholamines during late gestation (Fowden 1980b, Sperling et al 1980, Lang et al 1993, Jackson et al 2000.…”

Section: Introductionmentioning

confidence: 99%

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Maturation of pancreatic β-cell function in the fetal horse during late gestation

Fowden

Gardner²,

Ousey³

et al. 2005

Journal of Endocrinology

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At birth, the endocrine pancreas becomes more directly involved in the control of glycaemia than in utero. However, compared with other tissues, relatively little is known about the maturational changes that occur in the fetal endocrine pancreas in preparation for extrauterine life. This study examined the pancreatic -cell response to exogenous administration of glucose and arginine in fetal horses with respect to their gestational age and concentration of cortisol, the hormone responsible for prepartum maturation of other fetal tissues. Glucose administration had no effect on fetal insulin secretion between 175 and 230 days of gestation but evoked a rapid insulin response in fetuses closer to term (290-327 days). In late gestation, the -cell response was more rapid and greater in magnitude in fetuses with basal cortisol levels higher than 15 ng/ml than in those with lower cortisol values at the time of glucose administration. The fetal -cell response to arginine was unaffected by the rise in fetal plasma cortisol towards term. These findings show that there are maturational changes in pancreatic -cell function in fetal horses as cortisol levels rise close to term. Primarily, these prepartum maturational changes were in the mechanisms of glucose-stimulated insulin secretion, which would enable the cells to regulate glycaemia at the higher glucose levels observed postnatally.

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Maturation of Glucose-Stimulated Insulin Secretion in Fetal Sheep

Cited by 61 publications

References 39 publications

Development of insulin and proinsulin secretion in newborn pony foals

Development of insulin and proinsulin secretion in newborn pony foals

The role of amniotic fluid in influencing neonatal birth weight

Maturation of pancreatic β-cell function in the fetal horse during late gestation

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