Investigating the causes of low birth weight in contrasting ovine paradigms

Jacqueline Wallace, T R H Regnault, S W Limesand, William Hay, R V Anthony

Research output: Contribution to journalLiterature review

91 Citations (Scopus)

Abstract

Intrauterine growth restriction (IUGR) still accounts for a large incidence of infant mortality and morbity worldwide. Many of the circulatory and transport properties of the sheep placenta are similar to those of the human placenta and as such, the pregnant sheep offers an excellent model in which to study the development of IUGR. Two natural models of ovine IUGR are those of hyperthermic exposure during pregnancy, and adolescent overfeeding, also during pregnancy. Both models yield significantly reduced placental weights and an asymmetrically growth-restricted fetus, and display altered maternal hormone concentrations, indicative of an impaired trophoblast capacity. Additionally, impaired placental angiogenesis and uteroplacental blood flow appears to be an early defect in both the hyperthermic and adolescent paradigms. The effects of these alterations in placental functional development appear to be irreversible. IUGR fetuses are both hypoxic and hypoglycaemic, and have reduced insulin and insulin-like growth factor-1 (IGF-1), and elevated concentrations of lactate. However, fetal utilization of oxygen and glucose, on a weight basis, remain constant compared with control pregnancies. Maintained utilization of these substrates, in a substrate-deficient environment, suggests increased sensitivities to metabolic signals, which may play a role in the development of metabolic diseases in later adult life.

Original languageEnglish
Pages (from-to)19-26
Number of pages8
JournalThe Journal of Physiology
Volume565
Issue number1
Early online date17 Mar 2005
DOIs
Publication statusPublished - 15 May 2005

Keywords

  • fetal growth restriction
  • uterine artery doppler
  • placental growth
  • adolescent sheep
  • heat stress
  • growing adolescent
  • maternal nutrition
  • endocrine status
  • blood flows
  • model

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