In utero exposure to dexamethasone programs the development of the pancreatic β- and α-cells during early postnatal life.

Aims: The aim of the present study was to clarify if in utero exposure to DEX would affect the development of different types of pancreatic endocrine cells during postnatal life.

Main Methods: We investigated morphological and transcriptional features of both pancreatic β- and α-cell populations within the pancreatic islets during the early postnatal life of rats born to mothers treated with DEX (0.1 mg/kg) from day 14 to 19 of pregnancy. Untreated pregnant Wistar rats of the same age (12-week-old) were used as control (CTL). Pups were euthanized on the 1st, 3rd and 21st (PND1, PND3 and PND21, respectively) days of life, regardless of sex. Serum insulin and glucagon levels were also evaluated.

Key Findings: Rats born to DEX-treated mothers exhibited increased pancreatic α-cell mass, circulating glucagon levels and Gcg, Pax6, MafB and Nkx2.2 expression. Rats born to DEX-treated mothers also presented a rise in serum insulin levels on the PND3 that was paralleled by reduced β-cell mass. Such increase in serum insulin levels, instead, was associated with increased expression of genes associated to insulin secretion such as Gck and Slc2a2.

Significance: Altogether, the present data reveals yet unknown changes in endocrine pancreas during early postnatal life of rats exposed to DEX in utero. Such data may contribute to the understanding of the metabolic features of rats born to DEX-treated mothers.