Differential qualitative and temporal changes in the response of the hypothalamus-pituitary-adrenal axis in rats after localized or total-body irradiation.
Stress such as exposure to ionizing radiation is able to activate the hypothalamus-pituitary-adrenal axis. The present study sought to examine the effects of different configurations of a 10-Gy gamma irradiation in rats on the hypothalamus-pituitary-adrenal axis to understand the mechanism of negative feedback by glucocorticoids induced by ionizing radiation. Specifically, we determined adrenocorticotropin and corticosterone levels in plasma as well as corticotrophin-releasing factor expression in the paraventricular nucleus of the hypothalamus by in situ hybridization from 6 h to 4 days after total-body, abdominal or head irradiation. In this study, we found an activation of the hypothalamus-pituitary-adrenal axis after radiation exposure. Plasma adrenocorticotropin and corticosterone levels were significantly increased after total-body and abdominal irradiation 3 days after exposure, in parallel with decreased labeling of corticotrophin-releasing factor mRNA in the parvocellular region of the paraventricular nucleus of the hypothalamus. Our results suggest that ionizing radiation activates the neuroendocrine system to protect the organism from the occurrence of radiation-induced inflammation.
Lebaron-Jacobs
L
L
Institut de Radioprotection et de Sûreté Nucléaire, Département de Protection de la santé de l'Homme et de Dosimétrie, Section Autonome de Radiobiologie Appliquée à la Médecine, IRSN, F-92265 Fontenay-aux-Roses, Cédex, France. lebaron-jacobs@cea.fr
Wysocki
J
J
Griffiths
N M
NM
D000222:Adaptation, Physiological / Q000528:radiation effects; D000311:Adrenal Glands / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects; D000324:Adrenocorticotropic Hormone / Q000097:blood*; D000818:Animals; D003345:Corticosterone / Q000097:blood*; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism*; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D007030:Hypothalamo-Hypophyseal System / Q000166:cytology / Q000378:metabolism* / Q000528:radiation effects*; D007031:Hypothalamus / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects; D008297:Male; D009929:Organ Size / Q000528:radiation effects; D009928:Organ Specificity / Q000528:radiation effects; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects; D010913:Pituitary-Adrenal System / Q000166:cytology / Q000378:metabolism* / Q000528:radiation effects*; D011829:Radiation Dosage; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D014916:Whole-Body Irradiation / Q000379:methods
D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D003345:Corticosterone