Adrenocorticotropic hormone and corticosterone responses to acute hypoxia in the neonatal rat: effects of body temperature maintenance. Am J Physiol Regul Integr Comp Physiol 2011 Mar;300(3):R708-15
Date
12/31/2010Pubmed ID
21191001DOI
10.1152/ajpregu.00708.2010Scopus ID
2-s2.0-79954560214 (requires institutional sign-in at Scopus site) 19 CitationsAbstract
The corticosterone response to acute hypoxia in neonatal rats develops in the 1st wk of life, with a shift from ACTH independence to ACTH dependence. Acute hypoxia also leads to hypothermia, which may be protective. There is little information about the endocrine effects of body temperature maintenance during periods of neonatal hypoxia. We hypothesized that prevention of hypothermia during neonatal hypoxia would augment the adrenocortical stress response. Rat pups separated from their dams were studied at postnatal days 2 and 8 (PD2 and PD8). In one group of pups, body temperature was allowed to spontaneously decrease during a 30-min prehypoxia period. Pups were then exposed to 8% O(2) for 3 h and allowed to become spontaneously hypothermic or externally warmed (via servo-controlled heat) to maintain isothermia. In another group, external warming was used to maintain isothermia during the prehypoxia period, and then hypoxia with or without isothermia was applied. Plasma ACTH and corticosterone and mRNA expression of genes for upstream proteins involved in the steroidogenic pathway were measured. Maintenance of isothermia during the prehypoxia period increased baseline plasma ACTH at both ages. Hypothermic hypoxia caused an increase in plasma corticosterone; this response was augmented by isothermia at PD2, when the response was ACTH-independent, and at PD8, when the response was ACTH-dependent. In PD8 rats, isothermia also augmented the plasma ACTH response to hypoxia. We conclude that maintenance of isothermia augments the adrenocortical response to acute hypoxia in the neonate. Prevention of hypothermia may increase the stress response during neonatal hypoxia, becoming more pronounced with increased age.
Author List
Bruder ED, Kamer KJ, Guenther MA, 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
Acute DiseaseAdrenocorticotropic Hormone
Age Factors
Animals
Animals, Newborn
Body Temperature Regulation
Disease Models, Animal
Gene Expression Regulation
Hydrocortisone
Hypothermia
Hypoxia
Phosphoproteins
Pituitary-Adrenal System
RNA, Messenger
Rats
Rats, Sprague-Dawley
Receptor, Melanocortin, Type 2
Receptors, LDL
Time Factors