Pancreatic beta-cell function in the fetal foal and mare

Area of Science:

• Reproductive endocrinology
• Equine physiology
• Metabolic regulation

Background:

• Maternal and fetal insulin dynamics during equine gestation are not fully understood.
• Beta-cell function and its regulation in pregnant mares and their fetuses require further investigation.

Purpose of the Study:

• To investigate insulin secretion and beta-cell function in chronically catheterized fetal foals and mares during late gestation.
• To examine the fetal beta-cell response to exogenous glucose.
• To assess the impact of pregnancy on maternal insulin levels and glucose homeostasis.

Main Methods:

• Chronic catheterization of fetal foals and mares.
• Measurement of insulin and glucose concentrations in maternal and fetal blood.
• Analysis of insulin levels in relation to gestational age and glucose concentrations.
• Assessment of arterio-venous insulin differences across the gravid uterus.

Main Results:

• Fetal insulin concentrations (7.5 ± 0.5 μU/ml) were significantly lower than maternal concentrations (49.0 ± 5.0 μU/ml).
• Insulin levels in pregnant mares decreased with advancing gestation, while glucose remained stable.
• Fetal beta-cell responsiveness to glucose appeared to increase after 270 days of gestation.
• Maternal insulin levels correlated with endogenous glucose in both adults and fetuses.

Conclusions:

• Pregnancy significantly alters maternal insulin secretion, with a decline in insulin levels as gestation progresses.
• Fetal beta-cell function matures during late gestation, showing an enhanced response to glucose.
• The gravid uterus exhibits insulin uptake when maternal arterial insulin levels exceed 30 μU/ml.