No evidence for HPA reset in adult sheep with high blood pressure due to short prenatal exposure to dexamethasone.

Exposure of pregnant ewes to dexamethasone, for only 2 days (term approximately 150 days) at 27 days of gestation (group D), results in adult offspring with high blood pressure. In this study, hemorrhage stress has been used to see whether in these animals the responsiveness of the hypothalamo-pituitary-adrenal (HPA) axis is altered. In addition, we studied mineralocorticoid (MR) and glucocorticoid (GR) receptor gene expression in the hippocampus and GR gene expression in the hypothalamus using real-time PCR. Calculated areas under the adrenocorticotropin, arginine vasopressin, and cortisol plasma concentration curves in response to hemorrhage were similar between the control and group D. In addition, there was no significant difference in the expression of MR and GR in the hippocampus or GR in the hypothalamus between the control and group D. Taken together, it is unlikely that reset in the HPA axis plays a major role in this particular model of "programmed" hypertension.