title: Direct actions of ACTH on ovarian function of pseudopregnant rabbits.
abstract: The present study sought to assess whether the receptors for adrenocorticotropic hormone (ACTH), MC2R, and for glucocorticoid (GR) are expressed in corpora lutea (CL) of pseudopregnant rabbits and whether ACTH and cortisol exert any direct action on luteal function. By immunohistochemistry, positive reaction for MC2R and GR was detectable within luteal cells of CL. The MC2R mRNA levels were five-fold less abundant in day 9 than in day 4 CL (P<0.01). At both stages, ACTH agonist (ACTH 1-24) increased progesterone and prostaglandin (PG) E(2) (PGE(2)) (P<0.01), but reduced PGF(2α) releases (P<0.01) in vitro. ACTH 1-24 injection increased plasma cortisol levels within 4h (P<0.01), but decreased (P<0.01) progesterone 24h later and for the following two days. ACTH administration to estrous rabbits caused a transitory increase in blood progesterone concentrations (P<0.01). Daily injections of ACTH did not modify progesterone profile following ovulation. In conclusion, ACTH directly up-regulates CL progesterone production in vitro via MC2R, but indirectly hampers luteal function via cortisol-GR associated mechanism.
authors.affiliation: Department of Biopathological Science and Hygiene of Animal and Alimentary Production, Section of Physiology, Laboratory of Physiologic Biotechnology, University of Perugia, Italy.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Guelfi
authors.forename: Massimo
authors.initials: M
authors.lastname: Zerani
authors.forename: Gabriele
authors.initials: G
authors.lastname: Brecchia
authors.forename: Francesco
authors.initials: F
authors.lastname: Parillo
authors.forename: Cecilia
authors.initials: C
authors.lastname: Dall'Aglio
authors.forename: Margherita
authors.initials: M
authors.lastname: Maranesi
authors.forename: Cristiano
authors.initials: C
authors.lastname: Boiti
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000494:pharmacology* / Q000502:physiology; D000818:Animals; D002064:Buserelin / Q000494:pharmacology; D006063:Chorionic Gonadotropin / Q000378:metabolism; D003338:Corpus Luteum / Q000187:drug effects* / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D005260:Female; D006854:Hydrocortisone / Q000097:blood; D008184:Luteal Cells / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D011374:Progesterone / Q000097:blood / Q000378:metabolism; D011555:Pseudopregnancy / Q000378:metabolism*; D011817:Rabbits; D044103:Receptor, Melanocortin, Type 2 / Q000235:genetics / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D006063:Chorionic Gonadotropin; D044103:Receptor, Melanocortin, Type 2; D011965:Receptors, Glucocorticoid; D011374:Progesterone; D000324:Adrenocorticotropic Hormone; D019001:Nitric Oxide Synthase; D015232:Dinoprostone; D002064:Buserelin; D006854:Hydrocortisone