title: Effects of ghrelin on activation of Akt1 and ERK1/2 pathways during in vitro maturation of bovine oocytes.
abstract: The purpose of this study was to investigate the possible molecular pathways through which ghrelin accelerates in vitro oocyte maturation. Bovine cumulus-oocyte complexes (COCs), after 18 or 24 h maturation in the absence or the presence of 800 pg ml-1 of acylated ghrelin were either assessed for nuclear maturation or underwent in vitro fertilization in standard media and putative zygotes were cultured in vitro for 8 days. In a subset of COCs the levels of phosphorylated Akt1 and ERK1/2 (MAPK1/3) were assessed at the 0th, 6th, 10th, 18th and 24th hours of in vitro maturation (IVM). At 18 and 24 h no difference existed in the proportion of matured oocytes in the ghrelin-treated group, while in the control group more (P < 0.05) matured oocyte were found at 24 h. Oocyte maturation for 24 h in the presence of ghrelin resulted in substantially reduced (P < 0.05) blastocyst yield(16.3%) in comparison with that obtained after 18 h (30.0%) or to both control groups (29.3% and 26.9%, for 18 and 24 h in maturation, respectively). Ghrelin-treated oocytes expressed lower Akt1 phosphorylation rate at the 10th hour of IVM, and higher ERK1/2 at the 6th and 10th hours of IVM compared with controls. In cumulus cells, at the 18th and 24th hours of IVM Akt1 phosphorylation rate was higher in ghrelin-treated oocytes. Our results imply that ghrelin acts in a different time-dependent manner on bovine oocytes and cumulus cells modulating Akt1 and ERK1/2 phosphorylation, which brings about acceleration of the oocyte maturation process.
authors.affiliation: Department of Obstetrics and Reproduction,Veterinary Faculty,School of Health Sciences,Karditsa,University of Thessaly,Greece.
authors.forename: Thomas-Markos
authors.initials: TM
authors.lastname: Chouzouris
authors.affiliation: Department of Obstetrics and Reproduction,Veterinary Faculty,School of Health Sciences,Karditsa,University of Thessaly,Greece.
authors.forename: Eleni
authors.initials: E
authors.lastname: Dovolou
authors.affiliation: Department of Obstetrics and Reproduction,Veterinary Faculty,School of Health Sciences,Karditsa,University of Thessaly,Greece.
authors.forename: Fotini
authors.initials: F
authors.lastname: Krania
authors.affiliation: Department of Pharmacology,Veterinary Faculty,School of Health Sciences,Karditsa,University of Thessaly,Greece.
authors.forename: Ioannis S
authors.initials: IS
authors.lastname: Pappas
authors.affiliation: Department of Obstetrics and Gynecology,Faculty of Medicine,School of Health Sciences,Larissa,University of Thessaly,Greece.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Dafopoulos
authors.affiliation: Department of Obstetrics and Gynecology,Faculty of Medicine,School of Health Sciences,Larissa,University of Thessaly,Greece.
authors.forename: Ioannis E
authors.initials: IE
authors.lastname: Messinis
authors.affiliation: Department of Obstetrics and Gynecology,Faculty of Medicine,School of Health Sciences,Larissa,University of Thessaly,Greece.
authors.forename: George
authors.initials: G
authors.lastname: Anifandis
authors.affiliation: PO Box 199,43100 Karditsa,Greece.
authors.forename: Georgios S
authors.initials: GS
authors.lastname: Amiridis
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D054885:Cumulus Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D054439:Ghrelin / Q000494:pharmacology*; D059471:In Vitro Oocyte Maturation Techniques / Q000379:methods*; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D009865:Oocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*
chemical_list: D054439:Ghrelin; D051057:Proto-Oncogene Proteins c-akt
keywords: 
                 In vitro maturation; Akt1; Cumulus cells; ERK 1/2; Ghrelin; Oocyte