The Genomics of the Fetal Hypothalamic Cellular Response to Transient Hypoxia: Endocrine, Immune, and Metabolic Responses
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ABSTRACT:
ORGANISM(S): Ovis aries
PROVIDER: GSE43371 | GEO | 2014/01/16
SECONDARY ACCESSION(S): PRJNA185757
REPOSITORIES: GEO
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Project description:Fetuses respond to transient hypoxia (a common stressor in utero) with cellular responses that are appropriate for promoting survival of the fetus. The present experiment was performed to identify the acute genomic responses of the fetal hypothalamus to transient hypoxia. Three fetal sheep were exposed to 30 min of hypoxia and hypothalamic mRNA extracted from samples collected 30 min after return to normoxia. These samples were compared to those from 4 normoxic control fetuses using the Agilent 019921 ovine array. Differentially-regulated genes were analyzed by network analysis and by gene ontology analysis, identifying statistically significant overrepresentation of biological processes. Real-time PCR of selected genes supported the validity of the array data. Hypoxia induced increased expression of genes involved in response to oxygen stimulus, RNA splicing, anti-apoptosis, vascular smooth muscle proliferation, and positive regulation of Notch receptor target. Downregulated genes were involved in metabolism, antigen receptor-mediated immunity, macromolecular complex assembly, S-phase, translation elongation, RNA splicing, protein transport, and post-transcriptional regulation. We conclude that these results emphasize that the cellular response to hypoxia involves reduced metabolism, the involvement of the fetal immune system, and the importance of glucocorticoid signaling. 3 Ventilatory Hypoxia (VH) and 4 Control (con) fetuses. All fetuses were chronically catheterized and in late gestation. Hypoxia produced by low PO2 in maternal inspired gas for 30 min, followed by normoxia recovery for 30 min. Control fetuses maintained at normoxia for 30 min, followed by another 30 min of normoxia. Hypothalami collected for mRNA at end of normoxic recovery period.
2014-01-16 | E-GEOD-43371 | biostudies-arrayexpress
Project description:Transient hypoxia in pregnancy stimulates a physiological reflex response that redistributes blood flow and defends oxygen delivery to the fetal brain. The chemoreceptor reflex that is responsible for this physiological response is dependent on glutamatergic neurotransmission which, in times of vigorous activity, could produce cell death secondary to calcium uptake. We designed the present experiment to test the hypotheses that transient hypoxia produces damage of the cerebral cortex and that ketamine, an antagonist of NMDA receptors, reduces the damage. Late-gestation, chronically catheterized fetal sheep were subjected to a 30 min period of ventilatory hypoxia that decreased fetal PaO2 from 17±1 to 10±1 mm Hg, or normoxia (PaO2 17±1 mm Hg), with or without pretreatment (10 min before hypoxia/normoxia) with ketamine (3 mg/kg, iv). One day (24 h) after hypoxia/normoxia, fetal cerebral cortex was removed and mRNA extracted for transcriptomics and systems biology analysis. Hypoxia stimulated a transcriptomics response consistent with a reduction in cellular metabolism and an increase in inflammation. Ketamine pretreatment reduced both of these responses. The inflammation response modeled with transcriptomic system biology was validated by immunohistochemistry and showed increased abundance of microglia/macrophages after hypoxia in the cerebral cortical tissue that ketamine significantly reduced. We conclude that transient hypoxia produces inflammation of the fetal cerebral cortex and that ketamine, in a standard clinical dose, reduces the inflammation response. 4 groups: hypoxia, hypoxia plus ketamine, normoxia, normoxia plus ketamine. Hypoxia produced by low PO2 in maternal inspired gas for 30 min, followed by normoxia recovery for 23.5 hours. Control fetuses maintained at normoxia for 30 min, followed by another 23.5 h of normoxia. Fetal frontal cerebral cortex collected for mRNA at end of 23.5 h recovery period.
2016-04-06 | E-GEOD-76110 | biostudies-arrayexpress
Project description:The physiological response to hypoxia in the fetus has been extensively studied with regard to redistribution of fetal combined ventricular output and sparing of oxygen delivery to fetal brain and heart. However, little is known about the biochemical and molecular response of the fetal brain to transient hypoxia. The present study was designed to use transcriptomics and systems biology modeling to identify major biological responses of the fetal hypothalamus to transient hypoxia. We also investigated the effect of ketamine, an FDA approved anesthetic that has anti-inflammatory properties in various tissues. Chronically catheterized fetal sheep (122±5 days gestation) were subjected to 30 min hypoxia (relative reduction in PaO2 ~50 %) caused by infusion of nitrogen into the inspired gas of the pregnant ewe. Messenger RNA was isolated from fetal hypothalamus collected 24 hours after hypoxia, and was analyzed for gene expression using the Agilent 15.5k ovine microarray. Hypoxia increased expression of 280 and decreased expression of 357 genes. Genes increased by hypoxia were associated with immune responses, consistent with stimulation by lipopolysaccharide. Pretreatment of the fetuses with ketamine reduced immune/inflammation responses. Immunohistochemical analysis revealed that the number of microglia/macrophages in the anterior hypothalamus was increased by hypoxia and that the increase was blunted by ketamine. We conclude that transient hypoxia stimulates an inflammatory/immune response in the fetal hypothalamus and that transcriptomics/systems biology modeling is a useful and valid tool for investigation of biological function in the fetal sheep.
2017-07-31 | GSE82016 | GEO
Project description:Acute fetal hypoxia is a form of fetal stress that stimulates renal vasoconstriction and ischemia as a consequence of the physiological redistribution of combined ventricular output. We have demonstrated that hypoxia in late ovine gestation induces inflammation in the brain that is ameliorated by treatment with ketamine. We hypothesized that the fetal kidney would also respond to hypoxia with an increase in the expression of inflammatory genes, and that ketamine (an N-Methyl-D-aspartate receptor antagonist) would reduce or block this response. Enriched biological processes for the 427 upregulated genes were immune and inflammatory responses and for the 946 down-regulated genes were metabolic processes. Ketamine countered the effects of hypoxia on upregulated immune/inflammatory responses as well as the down-regulated metabolic responses. We conclude that our transcriptomics modeling predicts that hypoxia activates inflammatory pathways and reduces metabolism in the fetal kidney cortex, and ketamine blocks or ameliorates this response. The results suggest that ketamine may have therapeutic potential for protection from ischemic renal damage. At the time of surgery, fetuses were randomly assigned to one of the four groups (n=3-4/group): normoxic control, normoxia+ketamine, hypoxic control, and hypoxia+ketamine. Hypoxia was induced for 30 min in chronically catheterized fetal sheep (125±3 d; term=145-147d), with or without ketamine (3 mg/kg) administered intravenously to the fetus 10 min prior to hypoxia. Fetuses were euthanized 24 hours after the onset of hypoxia, and the kidney cortex were collected for RNA extraction and gene array studies. Gene expression was analyzed using ovine Agilent 15.5 k array and validated with qPCR. Significant differences in gene expression between groups were determined with t-statistics using the limma package for R (Pâ¤0.05).
2016-09-01 | E-GEOD-66920 | biostudies-arrayexpress
Project description:Transient hypoxia in pregnancy stimulates a physiological reflex response that redistributes blood flow and defends oxygen delivery to the fetal brain. The chemoreceptor reflex that is responsible for this physiological response is dependent on glutamatergic neurotransmission which, in times of vigorous activity, could produce cell death secondary to calcium uptake. We designed the present experiment to test the hypotheses that transient hypoxia produces damage of the hippocampus and that ketamine, an antagonist of NMDA receptors, reduces the damage. Late-gestation, chronically catheterized fetal sheep were subjected to a 30 min period of ventilatory hypoxia that decreased fetal PaO2 from 17±1 to 10±1 mm Hg, or normoxia (PaO2 17±1 mm Hg), with or without pretreatment (10 min before hypoxia/normoxia) with ketamine (3 mg/kg, iv). One day (24 h) after hypoxia/normoxia, fetal hippocampus was removed and mRNA extracted for transcriptomics and systems biology analysis. Hypoxia stimulated a transcriptomics response consistent with a an increase in inflammation (e.g., cytokine binding and response to LPS). Ketamine pretreatment reduced these responses. The inflammation response modeled with transcriptomic system biology was validated by immunohistochemistry and showed increased abundance of microglia/macrophages after hypoxia in the hippocampal tissue that ketamine significantly reduced. We conclude that transient hypoxia produces inflammation of the fetal hippocampus and that ketamine, in a standard clinical dose, reduces the inflammation response.
2017-08-31 | GSE97916 | GEO
Project description:Transient hypoxia in pregnancy stimulates a physiological reflex response that redistributes blood flow and defends oxygen delivery to the fetal brain. The chemoreceptor reflex that is responsible for this physiological response is dependent on glutamatergic neurotransmission which, in times of vigorous activity, could produce cell death secondary to calcium uptake. We designed the present experiment to test the hypotheses that transient hypoxia produces damage of the cerebral cortex and that ketamine, an antagonist of NMDA receptors, reduces the damage. Late-gestation, chronically catheterized fetal sheep were subjected to a 30 min period of ventilatory hypoxia that decreased fetal PaO2 from 17±1 to 10±1 mm Hg, or normoxia (PaO2 17±1 mm Hg), with or without pretreatment (10 min before hypoxia/normoxia) with ketamine (3 mg/kg, iv). One day (24 h) after hypoxia/normoxia, fetal cerebral cortex was removed and mRNA extracted for transcriptomics and systems biology analysis. Hypoxia stimulated a transcriptomics response consistent with a reduction in cellular metabolism and an increase in inflammation. Ketamine pretreatment reduced both of these responses. The inflammation response modeled with transcriptomic system biology was validated by immunohistochemistry and showed increased abundance of microglia/macrophages after hypoxia in the cerebral cortical tissue that ketamine significantly reduced. We conclude that transient hypoxia produces inflammation of the fetal cerebral cortex and that ketamine, in a standard clinical dose, reduces the inflammation response.
2016-04-06 | GSE76110 | GEO
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).
2014-07-01 | E-GEOD-52888 | biostudies-arrayexpress
Project description: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. The objective of this study was to use transcriptomics and systems analysis to determine significantly altered biological processes in the late gestation ovine fetal pituitary one hour after a 30 minute period of hypoxia, produced by lowering the inspired oxygen content in the maternal inspired gas. We found 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. The response is not consistent with gene regulation by HIF1A .
2015-10-01 | GSE69246 | GEO
Project description:The catecholamine norepinephrine is required for fetal survival, but its essential function is unknown. When catecholamine-deficient [tyrosine hydroxylase (Th) null] mouse fetuses die at E13.5-E14.5, they resemble wild type fetuses exposed to hypoxia. They exhibit bradycardia (28% reduction in heart rate), thin ventricular myocardium (20% reduction in tissue), epicardial detachment, and death with vascular congestion, hemorrhage and edema. At E12.5, prior to the appearance of morphological deficits associated with Th deletion, catecholamine-deficient fetuses are preferentially killed by experimentally-induced hypoxia and have lower tissue pO2 than wild type siblings. Catecholamine-deficient fetuses also induced HIF-1 target genes to a greater extent than wild type siblings, supporting the notion that null fetuses experience greater hypoxia or have an enhanced response to hypoxia. Hypoxia induces a 13-fold increase in plasma norepinephrine levels, which would be expected to increase heart rate, thereby, improving oxygen delivery in wild type mice. Surprisingly, increasing maternal oxygen (FiO2 33% or 63%) prevents the effects of catecholamine-deficiency, restoring heart rate, myocardial mass and survival of Th null fetuses. We suggest that norepinephrine mediates fetal survival by maintaining oxygen homeostasis as vulnerability to constitutive hypoxia increases as fetal growth accelerates during normal development. Keywords: Comparative with respect to genotype and oxygen conditions
2008-06-03 | GSE10341 | GEO
Project description:The catecholamine norepinephrine is required for fetal survival, but its essential function is unknown. When catecholamine-deficient [tyrosine hydroxylase (Th) null] mouse fetuses die at E13.5-E14.5, they resemble wild type fetuses exposed to hypoxia. They exhibit bradycardia (28% reduction in heart rate), thin ventricular myocardium (20% reduction in tissue), epicardial detachment, and death with vascular congestion, hemorrhage and edema. At E12.5, prior to the appearance of morphological deficits associated with Th deletion, catecholamine-deficient fetuses are preferentially killed by experimentally-induced hypoxia and have lower tissue pO2 than wild type siblings. Catecholamine-deficient fetuses also induced HIF-1 target genes to a greater extent than wild type siblings, supporting the notion that null fetuses experience greater hypoxia or have an enhanced response to hypoxia. Hypoxia induces a 13-fold increase in plasma norepinephrine levels, which would be expected to increase heart rate, thereby, improving oxygen delivery in wild type mice. Surprisingly, increasing maternal oxygen (FiO2 33% or 63%) prevents the effects of catecholamine-deficiency, restoring heart rate, myocardial mass and survival of Th null fetuses. We suggest that norepinephrine mediates fetal survival by maintaining oxygen homeostasis as vulnerability to constitutive hypoxia increases as fetal growth accelerates during normal development. Keywords: Comparative with respect to genotype and oxygen conditions The first aim was to compare gene expression of E12.5 mouse fetuses between wild type (Th+/+) versus tyrosine hydroxylase null (Th-/-) animals from normoxic dams. This resulted in 6 arrays. The second aim compared wild type and tyrosine hydroxylase null E12.5 fetuses from dam exposed to hypoxia (8% oxygen) for 6 hours prior to sacrifice at E12.5 of gestation. This resulted in 6 arrays. The third aim was to compare HIF-1 targets behind wt and null fetuses
2008-06-03 | E-GEOD-10341 | biostudies-arrayexpress