Central Fos expression in fetal and adult sheep after intraperitoneal hypertonic saline

A. Caston-Balderrama, M. J.M. Nijland, T. J. McDonald, M. G. Ross

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

We hypothesized that neural structures, involved in sensing extracellular body fluid composition in adult animals during an osmotic challenge, would show similar patterns of activation in fetal sheep. Eight adult sheep [4 hypertonic saline-treated adults (HYP-A), 4 isotonic saline- treated adults] and six near-term fetal sheep [3 hypertonic saline-treated fetuses (HYP-F), 3 isotonic saline-treated fetuses; 130 days gestation] were prepared with vascular and intraperitoneal catheters. Seventy-five minutes before tissue collection, hypertonic (1.5 M) or isotonic saline was infused via an intraperitoneal catheter to adult (18 ml/kg) or fetal sheep (6 ml/kg). Brains were examined for patterns of neuronal activation (demonstrated by Fos protein expression). HYP-A and HYP-F demonstrated similar acute increases in plasma osmolality (~10 mosmol/kgH2O) and comparable patterns of Fos expression within the organum vasculosum of the lamina terminalis (HYP-A, 67 ± 2 vs. HYP-F, 63 ± 6; means ± SE) and hypothalamic supraoptic (SON; HYP- A, 107 ± 8 vs. HYP-F, 102 ± 7) and paraventricular nuclei (PVN; HYP-A, 71 ± 18 vs. HYP-F, 124 ± 19). Fewer activated neurons were detected in HYP-A vs. HYP-F within the subfornical organ (HYP-A, 33 ± 8 vs. HYP-F, 91 ± 17) and median preoptic nucleus (HYP-A, 33 ± 5 vs. HYP-F, 70 ± 6). In adults and fetuses, counterstaining for arginine vasopressin revealed that neurons within the SON and PVN respond to osmotic challenge. These findings demonstrate that central osmoregulatory centers in adult and near-term fetal sheep are similarly activated by osmotic challenge.

Original languageEnglish (US)
Pages (from-to)H725-H735
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume276
Issue number2 45-2
DOIs
StatePublished - Feb 1999
Externally publishedYes

Keywords

  • Arginine vasopressin secretion
  • Circumventricular organs
  • Immunocytochemistry
  • Swallowing
  • Thirst

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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