Hepatic Insulin Resistance and Altered Gluconeogenic Pathway in Premature Baboons

Area of Science:

• Neonatal physiology
• Metabolic regulation
• Endocrinology

Background:

• Prematurity is linked to altered glucose metabolism and increased adult diabetes risk.
• The specific mechanisms of hepatic glucose regulation in preterm infants are not well understood.
• Early extrauterine adaptation impacts long-term metabolic health.

Purpose of the Study:

• To investigate developmental changes in glucose metabolism in preterm baboons.
• To analyze hepatic protein content and gene expression of key metabolic regulators.
• To compare glucose regulation in preterm neonates versus term neonates.

Main Methods:

• Delivery of fetal baboons at different gestational ages (67%, 75%, term).
• Survival and study of premature neonates (67% gestation) for two weeks.
• Serial hyperinsulinemic-euglycemic clamp studies in neonatal baboons.
• Analysis of hepatic phosphoenolpyruvate carboxykinase mRNA and insulin signaling proteins (insulin receptor-β, PI3K, IRS-1, Akt-1, GSK-3α).

Main Results:

• Premature baboons showed decreased endogenous glucose production (EGP) compared to term animals.
• Reduced phosphoenolpyruvate carboxykinase mRNA levels were observed in preterm baboons.
• Hepatic insulin signaling was impaired, with decreased levels of key proteins like insulin receptor-β, PI3K, IRS-1, and Akt-1 under insulin stimulation.
• Preterm baboons did not exhibit the normal increase in glycogen synthase kinase-3α from fetal to postnatal life.

Conclusions:

• Blunted hepatic insulin signaling in preterm infants may contribute to hyperglycemia.
• Impaired endogenous glucose production in preterm neonates can lead to hypoglycemia.
• These findings highlight critical early-life metabolic dysregulations in prematurity with potential long-term health consequences.