Effects of ghrelin on activation of Akt1 and ERK1/2 pathways during in vitro maturation of bovine oocytes. Issue 2 (7th March 2017)

• Record Type: Journal Article
• Authors: Chouzouris, Thomas-Markos; Dovolou, Eleni; Krania, Fotini; Pappas, Ioannis S.; Dafopoulos, Konstantinos; Messinis, Ioannis E.; Anifandis, George; Amiridis, Georgios S.
• Is Part Of: Zygote. Volume 25:Issue 2(2017)
• Page Start: 183
• Page End: 189
• Publication Date: 2017-03-07
• Subjects: Akt1, -- Cumulus cells, -- ERK 1/2, -- Ghrelin, -- In vitro maturation, -- Oocyte; Developmental biology -- Periodicals; Embryology -- Periodicals; Zygotes -- Periodicals; Gametes -- Periodicals; 571.864
• DOI: 10.1017/S096719941700003X
• Languages: English
• ISSNs: 0967-1994

Abstract

Summary: 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 0 th, 6 th, 10 th, 18 th and 24 th 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 10 th hour of IVM, and higher ERK1/2 at the 6 th and 10 th hours of IVM compared with controls. In cumulus cells, at the 18 th and 24 th 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.