Development of ER-alpha and ER-beta expression in the developing ovine brain and pituitary.

Fetal neuroendocrine development in late gestation is critical for maintenance of fetal homeostasis, growth, and readiness for birth. We designed the present study to identify the regional patterns of expression of the two main isoforms of the estrogen receptor, ER-alpha and ER-beta, in the developing ovine fetal brain. Fetal (80, 100, 120, 130, and 145 days gestation), neonatal (1 and 7 days), and adult sheep were euthanized and the following tissues were collected: pituitary, hypothalamus, hippocampus, cerebral cortex, and brainstem. Both ER's are expressed in the ovine brain as early as 80 days gestation, and the expression of both receptors appears to be developmentally regulated. We conclude that both forms of the estrogen receptor are expressed in fetal brain and pituitary throughout the latter half of gestation.