Post-hepatic insulin secretion in the fetal lamb

Area of Science:

• Comparative physiology
• Endocrinology
• Neonatal metabolism

Background:

• Understanding fetal and neonatal pancreatic beta-cell function is crucial for managing metabolic health.
• Insulin secretion plays a key role in glucose homeostasis.
• Limited data exists on the direct comparison of insulin secretion between fetal and newborn lambs.

Purpose of the Study:

• To compare post-hepatic insulin secretion rates between chronically catheterized fetal lambs and prematurely delivered newborn lambs.
• To assess the responsiveness of pancreatic beta-cells to glucose stimulation in both fetal and neonatal stages.
• To determine the metabolic clearance rate of insulin in fetal and newborn lambs.

Main Methods:

• Utilized chronically catheterized fetal lambs and prematurely delivered newborn lambs.
• Administered glucose infusions to induce a two-fold increase in plasma glucose concentration.
• Infused [131I]insulin to determine post-hepatic insulin secretion and metabolic clearance rates during steady-state plasma glucose.

Main Results:

• Both fetal and newborn lambs demonstrated increased post-hepatic insulin secretion rates in response to elevated plasma glucose.
• Fetal lambs showed a significant increase in plasma insulin concentration due to decreased insulin clearance and increased secretion.
• Newborn lambs exhibited increased insulin secretion but not a significant rise in plasma insulin, attributed to high variability.

Conclusions:

• Pancreatic beta-cells in both fetal and newborn lambs are similarly responsive to a two-fold increase in plasma glucose.
• The findings suggest comparable glucose-mediated insulin secretion capacity around the time of birth.
• Metabolic clearance rate of insulin may differ between fetal and newborn lambs, influencing plasma insulin levels.