Corticotropin-releasing hormone mediates the response to cold stress in the neonatal rat without compensatory enhancement of the peptide's gene expression.
A variety of stressors activate the hypothalamic-pituitary-adrenal axis, with secretion and compensatory enhanced synthesis of hypothalamic corticotropin-releasing hormone (CRH). Whether CRH is a major effector in the stress response of the neonatal rat and whether the peptide's gene expression is subsequently up-regulated are not fully understood. We studied the effect of cold-separation stress on plasma corticosterone (CORT) levels and CRH messenger RNA (CRH-mRNA) abundance in the paraventricular nucleus. Rats (4-16 days old) were subjected to maximal tolerated cold-separation. CORT and CRH-mRNA abundance were measured before and at several time points after stress. Cold-separation stress resulted in a significant plasma CORT increase in all age groups studied. This was abolished by the administration of an antiserum to CRH on both postnatal days 6 and 9. CRH-mRNA increased in rats aged 9 days or older, but not in 6-day-old rats, by 4 h after stress. These results suggest the presence of robust CRH-mediated adrenal responses to cold-separation stress in neonatal rats. Before postnatal day 9, however, the compensatory increase in CRH-mRNA abundance is minimal.
Yi
S J
SJ
Department of Neurology, University of Southern California, Los Angeles.
Baram
T Z
TZ
D000222:Adaptation, Physiological; D000375:Aging / Q000097:blood; D000818:Animals; D000831:Animals, Newborn / Q000097:blood / Q000502:physiology*; D003080:Cold Temperature; D003345:Corticosterone / Q000097:blood; D003346:Corticotropin-Releasing Hormone / Q000235:genetics* / Q000502:physiology*; D005786:Gene Expression Regulation; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013312:Stress, Physiological / Q000097:blood / Q000235:genetics / Q000503:physiopathology*; D013997:Time Factors
D012333:RNA, Messenger; D003346:Corticotropin-Releasing Hormone; D003345:Corticosterone