Maternal vitamin D deficiency during rat gestation elicits a milder phenotype compared to the mouse model: Implications for the placental glucocorticoid barrier.

Maternal vitamin D deficiency disturbs fetal development and programmes neurodevelopmental complications in offspring, possibly through increased fetal glucocorticoid exposure. We aimed to determine whether prenatal exposure to excess glucocorticoids underlies our rat model of early-life vitamin D deficiency, leading to altered adult behaviours. Vitamin D deficiency reduced the expression of the glucocorticoid-inactivating enzyme Hsd11b2 in the female placenta, but did not alter maternal glucocorticoid levels, feto-placental weights, or placental expression of other glucocorticoid-related genes at mid-gestation. This differs to the phenotype previously observed in vitamin D deficient mice, and highlights important modelling considerations.