Fetal dexamethasone exposure affects basal ornithine decarboxylase activity in developing rat brain regions and alters acute responses to hypoxia and maternal separation.

Published

Journal Article

Although glucocorticoids are widely used to stimulate fetal/neonatal lung function, they also interfere with cellular development in the central nervous system. Dexamethasone was administered to pregnant rats in late gestation at a dose (0.8 mg/kg) that lies just above the threshold for stimulation of lung surfactant synthesis, and the impact on ornithine decarboxylase (ODC) was evaluated in three brain regions. Dexamethasone treatment produced an initial inhibition of basal ODC activity followed by postnatal elevations, a pattern known to be associated with delays in cell replication and differentiation. Dexamethasone also interfered with the ability of the 1-day-old neonate to turn off ODC acutely in response to a 2-h period of maternal separation; as this response conserves energy in the absence of the dam, the effect of dexamethasone is maladaptive. Additionally, dexamethasone sensitized the neonatal brain to hypoxia: the acute increase of ODC associated with a 2-h exposure to 7% O2 was exacerbated in 8-day-old rats exposed to dexamethasone prenatally. These results suggest that administration of dexamethasone, in doses that promote respiratory competence, delays cell development in the central nervous system and renders the brain more vulnerable to adverse neonatal conditions, such as maternal separation or hypoxia.

Full Text

Duke Authors

Cited Authors

  • Carlos, RQ; Seidler, FJ; Lappi, SE; Slotkin, TA

Published Date

  • 1991

Published In

Volume / Issue

  • 59 / 2

Start / End Page

  • 69 - 77

PubMed ID

  • 2036470

Pubmed Central ID

  • 2036470

International Standard Serial Number (ISSN)

  • 0006-3126

Digital Object Identifier (DOI)

  • 10.1159/000243325

Language

  • eng

Conference Location

  • Switzerland