Ovine fetal estrogen sulfotransferase in brain regions important for hypothalamus-pituitary-adrenal axis control

Ovine parturition is initiated by increases in fetal hypothalamus -pituitary-adrenal (HPA) axis activity which, in turn, increase placental estrogen biosynthesis and ultimately increase uterine contractility. In addition to their action in the uterus, estrogens in fetal plasma augment fetal corticotropin (ACTH) secretion. In late gestation, estrone sulfate is more abundant in fetal plasma than unconjugated estrone and it is possible that there is interconversion of sulfoconjugated and unconjugated steroids within the fetal brain. We studied hypothalamus and brainstem tissue from fetal, neonatal, and adult sheep to test the hypothesis that the ovine brain contains estrogen sulfotransferase. Although no significant ontogenic pattern was revealed, the presence of estrogen sulfotransferase within the hypothalamus and brainstem was detectable. Immunohistochemistry revealed the presence of estrogen sulfotransferase in the paraventricular nucleus of the hypothalamus, the nucleus of the tractus solatarius, and the rostral ventral lateral medulla. We conclude that ovine fetal hypothalamus and brainstem contain estrogen sulfotransferase in brain regions important for HPA axis control. Copyright (C) 2000 S. Karger AG, Basel.