Prenatal dexamethasone exposure in rats: effects of dose, age at exposure, and drug-induced hypophagia on malformations and fetal organ weights.

Glucocorticoids cause stunting and cleft palate in rodents. The aim of this study is to identify fetal organs and developmental periods sensitive to stunting induced by maternal exposure to dexamethasone (DEX). DEX (0.2 or 0.4 mg/kg) or saline was given sc to pregnant CD albino rats on Gestation Days (GD) 9-14 or 14-19. On GD 20 dams were euthanized. Fetuses were weighed and examined for cleft palate. Eight fetuses/litter were randomly selected, and weights were obtained. Fetal skeletons were examined for abnormalities, and long bone measurements were taken. A dose-related decrease in maternal and fetal body weights occurred at both exposure periods. Developmental stage-specific malformations were noted in the high-dose group on GD 9-14 (cleft palate) and on GD 14-19 (wavy ribs). A dose-response in stunting occurred in all organs except cerebellum in at least one exposure period. Across both exposure periods the brain, heart, testes, and long bones were relatively resistant to DEX. Sensitive organs included thymus, spleen, adrenals, lungs, liver, and kidneys. DEX substantially reduced maternal food intake and increased water intake in some dams. Pair-feeding experiments suggested that the hypophagic effect of DEX was not responsible for the noted malformations and had little impact on growth stunting. The present findings have identified fetal organs, skeletal regions, and developmental periods sensitive to DEX exposure.