Differential effects of prenatal stress and glucocorticoid administration on postnatal growth and glucose metabolism in rats

Glucocorticoid administration during pregnancy programmes cardiovascular and metabolic functions in the adult offspring. Often, the control procedures are stressful per se and raise maternal glucocorticoid concentrations. This study compared the effects of maternal injection with dexamethasone (dex, 200 μg/kg) or saline with no treatment from 15 to 20 days of rat pregnancy on offspring growth and glucose metabolism. Near term, maternal corticosterone concentrations were higher in the saline-treated dams and lower in the dex-treated dams relative to untreated animals. In both male and female offspring, growth rate was measured for 14 weeks, and glucose tolerance was assessed between 12 and 13 weeks together with body fat content and plasma concentrations of insulin, leptin, and corticosterone between 14 and 15 weeks. Offspring liver was collected at different ages and was analyzed for glycogen content and gluconeogenic enzyme activity. Compared with untreated animals, both dex and saline treatments altered postnatal growth although adult body weight was unaffected. The two treatments had different effects on adult insulin concentrations and on hepatic glycogen content and gluconeogenic enzyme activities both pre- and postnatally. Relative to untreated animals, adult glucose tolerance was improved by maternal saline injection in males but not in females, while it was impaired in female offspring but not in male offspring of the dex-treated dams. Adult glucose tolerance was related to male body fat content but not to female body fat content. Dex and saline treatments of pregnant rats have differential sex-linked effects on the growth and glucose metabolism of their offspring, which indicates that the programming actions of natural and synthetic glucocorticoids may differ.