Genomics of estradiol-3-sulfate action in the ovine fetal hypothalamus

Abstract

In fetal sheep during late gestation sulfoconjugated estrogens in plasma reach a concentration 40–100 times greater than unconjugated estrogens. The objective of the present study was to determine the genomics of estradiol-3-sulfate (E2S) action in the ovine fetal brain. The hypothesis was that E2S stimulates genes involved in the neuroendocrine pathways that direct or facilitate fetal development at the end of gestation. Four sets of chronically catheterized ovine twin fetuses were studied (gestational age: 120–127 days gestation) with one infused with E2S intracerebroventricularly (1 mg/day) and the other remaining untreated (control). After euthanasia, mRNA samples were extracted from fetal brains. Only hypothalamic samples were employed for this study given the important function of this brain region in the control of the hypothalamus-pituitary-adrenal axis. Microarray analysis was performed following the Agilent protocol for one-color 8 × 15 microarrays, designed for Ovis aries. A total of 363 known genes were significantly upregulated by the E2S treatment ( P < 0.05). Network and enrichment analyses were performed using the Cytoscape/Bingo software, and the results validated by quantitative real-time PCR. The main overrepresented biological processes resulting from this analysis were feeding behavior, hypoxia response, and transforming growth factor signaling. Notably, the genes involved in the feeding behavior (neuropeptide Y and agouti-related protein) were the most strongly induced by the E2S treatment. In conclusion, E2S may be an important component of the mechanism for activating orexigenic, hypoxia responsiveness and neuroprotective pathways in the lamb as it approaches postnatal life.