Changes in the Hormonal Concentrations of Pregnant Rats and Their Fetuses Following Multiple Exposures to a Stressor During the Third Trimester

Human and animal studies indicate that stress during pregnancy can exert long-term effects on the development of the offspring, effects that appear to be mediated in part by the hypothalamic–pituitary–adrenal (HPA) axis. In this experiment changes in levels of a variety of HPA and other hormones in both pregnant rats and their fetuses were investigated. Trunk blood was collected from pregnant females and fetuses following repeated 45-min presentations of restraint, bright lights, and heat during the third trimester. In addition, testes were harvested from the male fetuses. Hormone concentrations were determined by radioimmunoassay. Pregnant females had elevated titers of plasma corticosterone, aldosterone, and ACTH for approximately 15 min following termination of the stressor. No differences were found for β-endorphin or prolactin. Fetuses showed a pattern of changes in plasma corticosterone and aldosterone that was similar to that of pregnant females, but no effect was observed for fetal ACTH titers. These results are consistent with a role of the HPA axis in the effects of gestational stress. Testicular levels of CRF on gestational day 21 were lower in fetuses of stressed females than in those of nonstressed females. The reduced levels of testicular CRF suggest that CRF may be involved in the altered pattern of sexual differentiation of males stressed during gestation.