title: Altered corticosteroid metabolism differentially affects pituitary corticotropin response.
abstract: To evaluate the effects of altered corticosteroid metabolism on the hypothalamic-pituitary-adrenal axis, we examined rats treated with glycyrrhizic acid (G rats) or rifampicin (R rats) for 7 days. The half-life of exogenously administered hydrocortisone as a substitute for corticosterone was longer in G rats and shorter in R rats, with no differences in basal plasma levels of ACTH or corticosterone. The ACTH responses to human corticotropin-releasing factor (CRF) or insulin-induced hypoglycemia were greater in G rats and tended to be smaller in R rats compared with those in the control rats, whereas the corticosterone response was similar. No difference was observed in the content and mRNA level of hypothalamic CRF among the groups. The number and mRNA level of CRF receptor and type 1 11 beta-hydroxysteroid dehydrogenase (11-HSD1) mRNA level in the pituitary were increased in G rats but not changed in R rats, suggesting that chronically increased intrapituitary corticosterone upregulates pituitary CRF receptor expression. In contrast, CRF mRNA levels in the pituitary were increased in R rats. Our data indicate novel mechanisms of corticosteroid metabolic modulation and the involvement of pituitary 11-HSD1 and CRF in glucocorticoid feedback physiology.
authors.affiliation: Third Department of Internal Medicine, Gifu University School of Medicine, Gifu 500-8705, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Hanafusa
authors.forename: Tomoatsu
authors.initials: T
authors.lastname: Mune
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Tanahashi
authors.forename: Yukinori
authors.initials: Y
authors.lastname: Isomura
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Suwa
authors.forename: Mako
authors.initials: M
authors.lastname: Isaji
authors.forename: Hisashi
authors.initials: H
authors.lastname: Daido
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Morita
authors.forename: Masanori
authors.initials: M
authors.lastname: Murayama
authors.forename: Keigo
authors.initials: K
authors.lastname: Yasuda
mesh_terms: D042842:11-beta-Hydroxysteroid Dehydrogenases; D000305:Adrenal Cortex Hormones / Q000378:metabolism*; D000324:Adrenocorticotropic Hormone / Q000097:blood / Q000378:metabolism*; D000818:Animals; D003345:Corticosterone / Q000097:blood; D003346:Corticotropin-Releasing Hormone / Q000235:genetics / Q000494:pharmacology; D019695:Glycyrrhizic Acid / Q000494:pharmacology; D006207:Half-Life; D006801:Humans; D006854:Hydrocortisone / Q000493:pharmacokinetics; D006913:Hydroxysteroid Dehydrogenases / Q000235:genetics; D007003:Hypoglycemia / Q000097:blood / Q000139:chemically induced; D007031:Hypothalamus / Q000378:metabolism; D007328:Insulin; D008297:Male; D010902:Pituitary Gland / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D018019:Receptors, Corticotropin-Releasing Hormone / Q000235:genetics; D012293:Rifampin / Q000494:pharmacology
chemical_list: D000305:Adrenal Cortex Hormones; D007328:Insulin; D012333:RNA, Messenger; D018019:Receptors, Corticotropin-Releasing Hormone; D019695:Glycyrrhizic Acid; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D006913:Hydroxysteroid Dehydrogenases; D042842:11-beta-Hydroxysteroid Dehydrogenases; D012293:Rifampin; D003345:Corticosterone; D006854:Hydrocortisone