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Transcriptomics of the fetal hypothalamic response to brachiocephalic occlusion and estradiol treatment.

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 artery occlusion (BCO) or sham occlusion. Half of the fetuses received subcutaneous pellets that increased plasma E2 concentrations within the physiological range. Hypothalamic mRNA was analyzed using the Agilent 8x15k ovine array (019921), processed and annotated as previously reported by our laboratory. Analysis of the data by ANOVA revealed that E2 differentially regulated (DR) 561 genes, and BCO DR 894 genes compared with control and E2+BCO DR 1,153 genes compared with 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. Brachiocephalic occlusion upregulated kinase pathways as well as genes associated with lymphocyte infiltration into the brain and downregulated neuropeptide synthesis. E2 upregulated immune- and apoptosis-related pathways after BCO and reduced kinase and epigenetic pathway responses to the BCO. Responses to BCO are different from responses to hypoxic hypoxia suggesting that mechanisms of responses to these two forms of brain hypoxia are distinct. We conclude that cerebral ischemia caused by BCO might stimulate lymphocyte infiltration into the brain and that this response appears to be modified by estradiol.

SUBMITTER: Wood CE

PROVIDER: S-EPMC4101578 | biostudies-literature | 2014 Jul

REPOSITORIES: biostudies-literature

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Transcriptomics of the fetal hypothalamic response to brachiocephalic occlusion and estradiol treatment.

Wood Charles E CE Rabaglino Maria Belen MB Richards Elaine E Denslow Nancy N Zarate Miguel A MA Chang Eileen I EI Keller-Wood Maureen M

Physiological genomics 20140513 14

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 artery occlusion (BCO) or sham occlusion. Half of the fetuses received subcutaneous pellets that increased ...[more]

PMID: 24824211

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Project description: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 (5 days@~250 M-NM-<g/day, increasing plasma E2 from 62M-BM-16 to 102M-BM-112 pg/mL). Hypothalamic mRNA was analyzed using the Agilent 8x15k ovine array (019921), processed and annotated as previously reported by our laboratory. Analysis of the data by ANOVA revealed that E2 differentially regulated (DR) 561 genes, and BCO DR 894 genes compared to control 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 (ie., 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. We conclude that array results are consistent with the results of more limited hypotheses previously published from these experiments. Chronically catheterized fetal sheep; 4 groups: control (no treatment); estradiol treatment (250 ug/day x 5 days); brachiocephalic occlusion of fetal sheep (BCO, 10 min, no other treatment); BCO plus estradiol (combination of estradiol treatment and BCO). All fetuses had blood drawn from chronically implanted catheters at 0, 5, 10, and 30 min after start of BCO or sham-BCO period. Fetal sheep 124-128 days gestation (term=147 days) at the time of study. Fetuses euthanized and fetal hypothalami collected for gene array studies 1 hour after first blood sample drawn (and start of BCO or sham-BCO period).

Project description:BACKGROUND:The late-gestation fetal sheep responds to hypoxia with physiological, neuroendocrine, and cellular responses that aid in fetal survival. The response of the fetus to hypoxia represents a coordinated effort to maximize oxygen transfer from the mother and minimize wasteful oxygen consumption by the fetus. While there have been many studies aimed at investigating the coordinated physiological and endocrine responses to hypoxia, and while immunohistochemical or in situ hybridization studies have revealed pathways supporting the endocrine function of the pituitary, there is little known about the coordinated cellular response of the pituitary to the hypoxia. RESULTS:Thirty min hypoxia (from 17.0±1.7 to 8.0±0.8 mm Hg, followed by 30 min normoxia) upregulated 595 and downregulated 790 genes in fetal pituitary (123-132 days' gestation; term = 147 days). Network inference of up- and down- regulated genes revealed a high degree of functional relatedness amongst the gene sets. Gene ontology analysis revealed upregulation of cellular metabolic processes (e.g., RNA synthesis, response to estrogens) and downregulation of protein phosphorylation, protein metabolism, and mitosis. Genes found to be at the center of the network of upregulated genes included genes important for purine binding and signaling. At the center of the downregulated network were genes involved in mRNA processing, DNA repair, sumoylation, and vesicular trafficking. Transcription factor analysis revealed that both up- and down-regulated gene sets are enriched for control by several transcription factors (e.g., SP1, MAZ, LEF1, NRF1, ELK1, NFAT, E12, PAX4) but not for HIF-1, which is known to be an important controller of genomic responses to hypoxia. CONCLUSIONS:The multiple analytical approaches used in this study suggests that the acute response to 30 min of transient hypoxia in the late-gestation fetus results in reduced cellular metabolism and a pattern of gene expression that is consistent with cellular oxygen and ATP starvation. In this early time point, we see a vigorous gene response. But, like the hypothalamus, the transcriptomic response is not consistent with mediation by HIF-1. If HIF-1 is a significant controller of gene expression in the fetal pituitary after hypoxia, it must be at a later time.

Dataset Information

Transcriptomics of the fetal hypothalamic response to brachiocephalic occlusion and estradiol treatment.

Publications

Transcriptomics of the fetal hypothalamic response to brachiocephalic occlusion and estradiol treatment.

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