title: Corticosterone-induced negative feedback mechanisms within the hypothalamo-pituitary-adrenal axis of the chicken.
abstract: This paper reports the results of in vivo and in vitro experiments on the feedback effects of corticosterone on the hypothalamo-pituitary-adrenal axis in embryos at day 18 of incubation and in 9-day-old chickens. In vivo, a significant negative feedback was detected on the levels of corticotropin-releasing factor (CRF) precursor (proCRF) mRNA and on the plasma concentration of corticosterone, two hours after a single intravenous injection with 40 microg corticosterone. In contrast, the levels of CRF peptide in the hypothalamic area, the CRF receptor type 1 (CRF-R1) mRNA and pro-opiomelanocortin (POMC) mRNA levels in the pituitary were not affected by the in vivo administration of corticosterone. In vitro, incubation with 1 microM corticosterone did not affect the CRF-R1 mRNA levels in the pituitary, but significant feedback inhibition was observed on the POMC mRNA levels. These in vitro effects were the same at the two ages studied. The in vitro feedback effect on the proCRF gene expression, however, differed with age. In 9-day-old animals a decrease in gene expression was observed which was not detectable in embryonic tissue at day 18 of the ontogeny.
authors.affiliation: Laboratory of Comparative Endocrinology, Zoological Institute, K U Leuven, Naamsestraat 61, B-3000 Leuven, Belgium.
authors.forename: Kristien
authors.initials: K
authors.lastname: Vandenborne
authors.forename: Bert
authors.initials: B
authors.lastname: De Groef
authors.forename: Sofie M E
authors.initials: SM
authors.lastname: Geelissen
authors.forename: Eduard R
authors.initials: ER
authors.lastname: Kühn
authors.forename: Veerle M
authors.initials: VM
authors.lastname: Darras
authors.forename: Serge
authors.initials: S
authors.lastname: Van der Geyten
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D002645:Chickens / Q000378:metabolism*; D003345:Corticosterone / Q000097:blood / Q000494:pharmacology*; D003346:Corticotropin-Releasing Hormone / Q000235:genetics / Q000378:metabolism*; D025461:Feedback, Physiological; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects* / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism; D007275:Injections, Intravenous; D010902:Pituitary Gland / Q000378:metabolism; D010913:Pituitary-Adrenal System / Q000187:drug effects* / Q000378:metabolism; D011333:Pro-Opiomelanocortin / Q000235:genetics; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D018019:Receptors, Corticotropin-Releasing Hormone / Q000235:genetics; D013997:Time Factors; D000099052:CRF Receptor, Type 1
chemical_list: D011498:Protein Precursors; D012333:RNA, Messenger; D018019:Receptors, Corticotropin-Releasing Hormone; C041645:pro-corticotropin releasing hormone; D000099052:CRF Receptor, Type 1; D011333:Pro-Opiomelanocortin; D003346:Corticotropin-Releasing Hormone; D003345:Corticosterone