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Elevated corticosterone and inhibition of ACTH responses to CRH and ether in the neonatal rat: effect of hypoxia from birth. Am J Physiol Regul Integr Comp Physiol 2003 Nov;285(5):R1224-30

Date

07/12/2003

Pubmed ID

12855418

DOI

10.1152/ajpregu.00259.2003

Scopus ID

2-s2.0-0142249309   25 Citations

Abstract

Hypoxia is a common cause of neonatal morbidity and mortality. We have previously demonstrated a dramatic ACTH-independent activation of adrenal steroidogenesis in hypoxic neonatal rats, leading to increases in circulating corticosterone levels. The purpose of the present study was to determine if this ACTH-independent increase in corticosterone inhibits the ACTH response to acute stimuli. Neonatal rats were exposed to normoxia (control) or hypoxia from birth to 5 or 7 days of age. At the end of the exposure, plasma ACTH and corticosterone were measured before and after either ether vapors were administered for 3 min or CRH (10 microg/kg) was given intraperitoneally. Thyroid function, pituitary pro-opiomelanocortin (POMC) mRNA and ACTH content, and hypothalamic corticotropin-releasing hormone (CRH), neuropeptide Y (NPY), and AVP mRNA were also assessed. Hypoxia led to a significant increase in corticosterone without a large increase in ACTH, confirming previous studies. The ACTH responses to ether or CRH administration were almost completely inhibited in hypoxic pups. Hypoxia did not affect the established regulators of the neonatal hypothalamic-pituitary-adrenal axis, including pituitary POMC or ACTH content, hypothalamic CRH, NPY, or AVP mRNA (parvo- or magnocellular), or thyroid function. We conclude that hypoxia from birth to 5 or 7 days of age leads to an attenuated ACTH response to acute stimuli, most likely due to glucocorticoid negative feedback. The neural and biochemical mechanism of this effect has yet to be elucidated.

Author List

Raff H, Jacobson L, Cullinan WE

Authors

William E. Cullinan PhD Adjunct Associate Professor in the Neurosurgery department at Medical College of Wisconsin
Hershel Raff PhD Professor in the Medicine department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Adrenocorticotropic Hormone
Anesthetics, Inhalation
Animals
Animals, Newborn
Arginine Vasopressin
Corticosterone
Corticotropin-Releasing Hormone
Ether
Female
Gene Expression
Hypothalamo-Hypophyseal System
Hypoxia
Neuropeptide Y
Pregnancy
Pro-Opiomelanocortin
Rats
Rats, Sprague-Dawley
Stress, Physiological
jenkins-FCD Prod-484 8aa07fc50b7f6d102f3dda2f4c7056ff84294d1d