Adrenocortical sensitivity to ACTH in neonatal rats: correlation of corticosterone responses and adrenal cAMP content. Am J Physiol Regul Integr Comp Physiol 2014 Aug 01;307(3):R347-53
Date
06/06/2014Pubmed ID
24898842DOI
10.1152/ajpregu.00125.2014Scopus ID
2-s2.0-84905258146 (requires institutional sign-in at Scopus site) 10 CitationsAbstract
A coordinated hypothalamic-pituitary-adrenal axis response is important for the survival of newborns during stress. We have previously shown that prior to postnatal day (PD) 5, neonatal rats exposed to hypoxia (one of the most common stressors effecting premature neonates) exhibit a large corticosterone response with a minimal increase in immunoassayable plasma ACTH and without a detectable increase in adrenal cAMP content (the critical second messenger). To explore the phenomenon of ACTH-stimulated steroidogenesis in the neonate, we investigated the adrenal response to exogenous ACTH in the normoxic neonatal rat. Rat pups at PD2 and PD8 were injected intraperitoneally with porcine ACTH at low, moderate, or high doses (1, 4, or 20 μg/kg body wt). Trunk blood and whole adrenal glands were collected at baseline (before injection) and 15, 30, or 60 min after the injection. ACTH stimulated corticosterone release in PD2 and PD8 pups. In PD2 pups, plasma corticosterone at baseline and during the response to ACTH injection was greater than values measured in PD8 pups, despite lower adrenal cAMP content in PD2 pups. Specifically, the low and moderate physiological ACTH doses produced a large corticosterone response in PD2 pups without a change in adrenal cAMP content. At extremely high, pharmacological levels of plasma ACTH in PD2 pups (exceeding 3,000 pg/ml), an increase in adrenal cAMP was measured. We conclude that physiological increases in plasma ACTH may stimulate adrenal steroidogenesis in PD2 pups through a non-cAMP-mediated pathway.
Author List
Bodager J, Gessert T, Bruder ED, Gehrand A, Raff HAuthor
Hershel Raff PhD Professor in the Academic Affairs department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Adrenal CortexAdrenocorticotropic Hormone
Aging
Animals
Animals, Newborn
Corticosterone
Cyclic AMP
Dose-Response Relationship, Drug
Female
Hypothalamo-Hypophyseal System
Models, Animal
Pituitary-Adrenal System
Pregnancy
Rats
Rats, Sprague-Dawley
Signal Transduction