Response of the Hypothalamic-Hypophyseal Adrenal Axis to Stress: Observations in Fetal and Caesarean Newborn Rats.

Abstract

Summary A fetal rat given epinephrine showed a depletion of the ascorbic acid in the adrenals, but a decapitated fetus did not, nor did an intact (nondecapitated) fetus given saline instead of epinephrine. In a premature newborn obtained by Caesarean section (detached from placenta or not detached), injection of epinephrine did not cause a depletion of the ascorbic acid. These observations support the views that in the rat the hypothalamic-hypophyseal adrenal axis begins to function before birth and that after delivery this axis temporarily becomes refractory to stimulation by injected epinephrine.