Cortisol and ACTH responses to severe asphyxia in preterm fetal sheep

Vincent Roelfsema, Alistair J Gunn, Mhoyra Fraser, Josine S Quaedackers, Laura Bennet*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

19 Citations (Scopus)

Abstract

It has been hypothesized that the hypothalamic-pituitary-adrenal (HPA) axis is immature in the preterm fetus and that this compromises their ability to adapt to hypoxic stress; however, there are few direct data. We therefore examined the effects of asphyxia on HPA responses in chronically instrumented preterm fetal sheep (104 days of gestation; term is 147 days), allocated to a sham control group (n = 7) or 25 min of complete umbilical cord occlusion (n = 8), followed by recovery for 72 h. During umbilical cord occlusion there was a rapid rise in ACTH levels (230.4 +/- 63.5 versus 14.1 +/- 1.8 ng ml(-1) in sham controls, 16-fold) and cortisol levels (7.4 +/- 4.9 versus 0.2 +/- 0.1 ng ml(-1), 31-fold), with further increases after release of cord occlusion. ACTH levels were normalized by 24 h, while plasma cortisol levels returned to sham control values 72 h after asphyxia. Fetal arterial blood pressure was elevated in the first 36 h, with a marked increase in femoral vascular resistance, and correlated positively with cortisol levels after asphyxia (P = 0.05). In conclusion, the preterm fetus shows a brisk, substantial HPA response to severe hypoxia.

Original languageEnglish
Pages (from-to)545-55
Number of pages11
JournalExperimental Physiology
Volume90
Issue number4
DOIs
Publication statusPublished - Jul-2005
Externally publishedYes

Keywords

  • Adrenocorticotropic Hormone/metabolism
  • Animals
  • Asphyxia/metabolism
  • Blood Gas Analysis
  • Blood Glucose/metabolism
  • Female
  • Fetal Blood/chemistry
  • Fetus/blood supply
  • Gestational Age
  • Hydrocortisone/metabolism
  • Lactic Acid/blood
  • Pregnancy
  • Regional Blood Flow/physiology
  • Sheep
  • Spinal Cord/physiology
  • Umbilical Cord/physiology

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