Chronic fetal hypoglycemia inhibits the later steps of stimulus-secretion coupling in pancreatic β-cells

Paul J. Rozance, Sean W Limesand, Gary O. Zerbe, William W. Hay

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

We measured the impact of chronic late gestation hypoglycemia on pancreatic islet structure and function to determine the cause of decreased insulin secretion in this sheep model of fetal nutrient deprivation. Late gestation hypoglycemia did not decrease pancreas weight, insulin content, β-cell area, β-cell mass, or islet size. The pancreatic islet isolation procedure selected a group of islets that were larger and had an increased proportion of β-cells compared with islets measured in pancreatic sections, but there were no morphologic differences between islets isolated from control and hypoglycemic fetuses. The rates of glucose-stimulated pancreatic islet glucose utilization (126.2 ± 25.3 pmol glucose·islet -1·h-1, hypoglycemic, vs. 93.5 ± 5.5 pmol glucose·islet-1·h-1, control, P = 0.47) and oxidation (10.5 ± 1.7 pmol glucose·islet -1·h-1, hypoglycemic, vs. 10.6 ± 1.6 pmol glucose·islet-1·h-1, control) were not different in hypoglycemic fetuses compared with control fetuses. Chronic late gestation hypoglycemia decreased insulin secretion in isolated pancreatic islets by almost 70% in response to direct nonnutrient membrane depolarization and in response to increased extracellular calcium entry. β-Cell ultrastructure was abnormal with markedly distended rough endoplasmic reticulum in three of the seven hypoglycemic fetuses studied, but in vitro analysis of hypoglycemic control islets showed no evidence that these changes represented endoplasmic reticulum stress, as measured by transcription of glucose regulatory protein-78 and processing of X-box binding protein-1. In conclusion, these studies show that chronic hypoglycemia in late gestation decreases insulin secretion by inhibiting the later steps of stimulus-secretion coupling after glucose metabolism, membrane depolarization, and calcium entry.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume292
Issue number5
DOIs
StatePublished - May 2007

Fingerprint

Hypoglycemia
Hypoglycemic Agents
Islets of Langerhans
Fetus
Insulin
Glucose
Pregnancy
Depolarization
Calcium
Membranes
Endoplasmic Reticulum Stress
Rough Endoplasmic Reticulum
Transcription
Metabolism
Nutrients
Pancreas
Sheep
Carrier Proteins
Weights and Measures
Food

Keywords

  • Glucose
  • Insulin secretion
  • Metabolism
  • Pancreatic islet
  • Unfolded protein response

ASJC Scopus subject areas

  • Physiology
  • Endocrinology
  • Biochemistry

Cite this

Chronic fetal hypoglycemia inhibits the later steps of stimulus-secretion coupling in pancreatic β-cells. / Rozance, Paul J.; Limesand, Sean W; Zerbe, Gary O.; Hay, William W.

In: American Journal of Physiology - Endocrinology and Metabolism, Vol. 292, No. 5, 05.2007.

Research output: Contribution to journalArticle

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abstract = "We measured the impact of chronic late gestation hypoglycemia on pancreatic islet structure and function to determine the cause of decreased insulin secretion in this sheep model of fetal nutrient deprivation. Late gestation hypoglycemia did not decrease pancreas weight, insulin content, β-cell area, β-cell mass, or islet size. The pancreatic islet isolation procedure selected a group of islets that were larger and had an increased proportion of β-cells compared with islets measured in pancreatic sections, but there were no morphologic differences between islets isolated from control and hypoglycemic fetuses. The rates of glucose-stimulated pancreatic islet glucose utilization (126.2 ± 25.3 pmol glucose·islet -1·h-1, hypoglycemic, vs. 93.5 ± 5.5 pmol glucose·islet-1·h-1, control, P = 0.47) and oxidation (10.5 ± 1.7 pmol glucose·islet -1·h-1, hypoglycemic, vs. 10.6 ± 1.6 pmol glucose·islet-1·h-1, control) were not different in hypoglycemic fetuses compared with control fetuses. Chronic late gestation hypoglycemia decreased insulin secretion in isolated pancreatic islets by almost 70{\%} in response to direct nonnutrient membrane depolarization and in response to increased extracellular calcium entry. β-Cell ultrastructure was abnormal with markedly distended rough endoplasmic reticulum in three of the seven hypoglycemic fetuses studied, but in vitro analysis of hypoglycemic control islets showed no evidence that these changes represented endoplasmic reticulum stress, as measured by transcription of glucose regulatory protein-78 and processing of X-box binding protein-1. In conclusion, these studies show that chronic hypoglycemia in late gestation decreases insulin secretion by inhibiting the later steps of stimulus-secretion coupling after glucose metabolism, membrane depolarization, and calcium entry.",
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N2 - We measured the impact of chronic late gestation hypoglycemia on pancreatic islet structure and function to determine the cause of decreased insulin secretion in this sheep model of fetal nutrient deprivation. Late gestation hypoglycemia did not decrease pancreas weight, insulin content, β-cell area, β-cell mass, or islet size. The pancreatic islet isolation procedure selected a group of islets that were larger and had an increased proportion of β-cells compared with islets measured in pancreatic sections, but there were no morphologic differences between islets isolated from control and hypoglycemic fetuses. The rates of glucose-stimulated pancreatic islet glucose utilization (126.2 ± 25.3 pmol glucose·islet -1·h-1, hypoglycemic, vs. 93.5 ± 5.5 pmol glucose·islet-1·h-1, control, P = 0.47) and oxidation (10.5 ± 1.7 pmol glucose·islet -1·h-1, hypoglycemic, vs. 10.6 ± 1.6 pmol glucose·islet-1·h-1, control) were not different in hypoglycemic fetuses compared with control fetuses. Chronic late gestation hypoglycemia decreased insulin secretion in isolated pancreatic islets by almost 70% in response to direct nonnutrient membrane depolarization and in response to increased extracellular calcium entry. β-Cell ultrastructure was abnormal with markedly distended rough endoplasmic reticulum in three of the seven hypoglycemic fetuses studied, but in vitro analysis of hypoglycemic control islets showed no evidence that these changes represented endoplasmic reticulum stress, as measured by transcription of glucose regulatory protein-78 and processing of X-box binding protein-1. In conclusion, these studies show that chronic hypoglycemia in late gestation decreases insulin secretion by inhibiting the later steps of stimulus-secretion coupling after glucose metabolism, membrane depolarization, and calcium entry.

AB - We measured the impact of chronic late gestation hypoglycemia on pancreatic islet structure and function to determine the cause of decreased insulin secretion in this sheep model of fetal nutrient deprivation. Late gestation hypoglycemia did not decrease pancreas weight, insulin content, β-cell area, β-cell mass, or islet size. The pancreatic islet isolation procedure selected a group of islets that were larger and had an increased proportion of β-cells compared with islets measured in pancreatic sections, but there were no morphologic differences between islets isolated from control and hypoglycemic fetuses. The rates of glucose-stimulated pancreatic islet glucose utilization (126.2 ± 25.3 pmol glucose·islet -1·h-1, hypoglycemic, vs. 93.5 ± 5.5 pmol glucose·islet-1·h-1, control, P = 0.47) and oxidation (10.5 ± 1.7 pmol glucose·islet -1·h-1, hypoglycemic, vs. 10.6 ± 1.6 pmol glucose·islet-1·h-1, control) were not different in hypoglycemic fetuses compared with control fetuses. Chronic late gestation hypoglycemia decreased insulin secretion in isolated pancreatic islets by almost 70% in response to direct nonnutrient membrane depolarization and in response to increased extracellular calcium entry. β-Cell ultrastructure was abnormal with markedly distended rough endoplasmic reticulum in three of the seven hypoglycemic fetuses studied, but in vitro analysis of hypoglycemic control islets showed no evidence that these changes represented endoplasmic reticulum stress, as measured by transcription of glucose regulatory protein-78 and processing of X-box binding protein-1. In conclusion, these studies show that chronic hypoglycemia in late gestation decreases insulin secretion by inhibiting the later steps of stimulus-secretion coupling after glucose metabolism, membrane depolarization, and calcium entry.

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