Modeling the transcriptomics response of the late‐gestation fetal hypothalamus to estradiol and brachiocephalic occlusion (910.10)

Abstract

Estradiol (E2) is a well‐known modulator of fetal neuroendocrine activity, and has been proposed as a critical endocrine signal readying the fetus for birth and postnatal life. To investigate the modulatory role of E2 on fetal stress responsiveness and the response of the fetal brain to asphyxic stress, we subjected chronically catheterized fetal sheep to a transient (10 min) brachiocephalic occlusion or sham occlusion. Half of the fetuses received subcutaneous pellets that released E2 (~250 μg/day, increasing plasma E2 from 62±6 to 102±12 pg/mL). Hypothalamic mRNA was analyzed using the Agilent 8x15k ovine array (019921), processed and annotated as previously reported by our laboratory. Data were analyzed by ANOVA, using JMP Genomics (SAS Institute), revealing that E2 differentially regulated (DR) 561 genes, BCO DR 894 genes and estradiol+BCO DR 1153 genes compared to BCO alone (all p<0.05). E2 upregulated epigenetic pathways and downregulated local steroid biosynthesis, but did not significantly involve genes known to directly respond to the estrogen receptor (contain ERE sequences). BCO upregulated kinase pathways as well as genes associated with lymphocyte infiltration into the brain, and downregulated neuropeptide synthesis. E2 upregulated immune‐ and apopotosis‐ related pathways after BCO, and reduced kinase and epigenetic pathway responses to the BCO. Array results are consistent with the results of more limited hypotheses previously published from these experiments and real‐time PCR validation of neuropeptide and immune‐related genes (CRH, CRHBP, POMC, AGRP, IL1β, TNFα) confirmed the array results. We conclude that increased E2 plasma concentrations invoke epigenetic pathways and appear to exacerbate brain inflammation after BCO. Actions of E2 in the fetal brain might not be dependent on ERα‐mediated gene transcription.Grant Funding Source: Supported by HD033053 and DK076541