Expression and distribution of glucocorticoid receptors in the ovine fetal adrenal cortex: effect of long-term hypoxia.

This study was designed to determine if long-term hypoxia (LTH) alters adrenal glucocorticoid receptor (GR) expression in the ovine fetal adrenal cortex. Ewes were maintained at 3820 m from approximately 30 to 138 to 140 days' gestation, and fetal adrenals were collected. Western analysis revealed two approximately 94-kDa GR-alpha isoforms and a lower molecular weight (45 kDa) form. A decreasing trend in the ratio of 94-kDa/45-kDa bands following LTH suggested an increase in GR turnover. Immunohistochemistry demonstrated dense GR staining in the zona glomerulosa with minimal staining in the zona fasciculata in the control group, while dense staining was observed throughout the cortex in LTH. Western analysis and reverse transcription polymerase chain reaction confirmed that the GR- beta isoform is not present or expressed at extremely low levels in the fetal adrenal, hypothalamus, pituitary, and placenta. These data indicate that LTH alters GR-alpha function in the fetal adrenal cortex and suggest that GR-beta is not expressed in sheep.