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Meiotic arrest maintained by cAMP during the initiation of maturation enhances meiotic potential and developmental competence and reduces polyspermy of IVM/IVF porcine oocytes

Published online by Cambridge University Press:  27 November 2003

Tamás Somfai
Affiliation:
Developmental Biology Department, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan Animal Reproduction Unit, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan University of West Hungary, Institute of Animal Breeding, Mosonmagyaróvár, Hungary
Kazuhiro Kikuchi
Affiliation:
Genetic Diversity Department, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan
Akira Onishi
Affiliation:
Developmental Biology Department, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan
Masaki Iwamoto
Affiliation:
Prime Tech Ltd, Tsuchiura, Ibaraki 305-0841, Japan
Dai-ichiro Fuchimoto
Affiliation:
Developmental Biology Department, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan
Ágnes Bali Papp
Affiliation:
University of West Hungary, Institute of Animal Breeding, Mosonmagyaróvár, Hungary
Eimei Sato
Affiliation:
Animal Reproduction Unit, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan
Takashi Nagai
Affiliation:
Developmental Biology Department, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan

Abstract

We investigated effects of invasive adenylate cyclase (iAC), 3-isobutyl-1-methylxanthine (IBMX) and dibutyryl cyclic AMP (dbcAMP) on porcine oocyte in vitro maturation (IVM), in vitro fertilisation (IVF) and subsequent embryonic development. Porcine oocytes were collected in Hepes-buffered NCSU-37 supplemented with or without 0.1 μg/ml iAC and 0.5 mM IBMX. IVM was performed in a modified NCSU-37 supplemented with or without 1 mM dbcAMP for 22 h and then without dbcAMP for an additional 24 h. After IVF, oocytes were cultured in vitro for 6 days. After 12 h of IVM, no difference in nuclear status was observed irrespective of supplementation with these chemicals during collection and IVM. At 22 h, most (95%) of the oocytes cultured with dbcAMP remained at the germinal vesicle (GV) stage, whereas 44.3% of the oocytes cultured without dbcAMP underwent GV breakdown. At 36 h, oocytes cultured with dbcAMP had progressed to prometaphase I or metaphase I (MI) (32.6% and 49.3%, respectively), whereas non-treated oocytes had progressed further to anaphase I, telophase I or metaphase II (MII) (13.6%, 14.3% and 38.0%, respectively). At 46 h, the rate of matured oocytes at MII was higher in oocytes cultured with dbcAMP (81%) than without dbcAMP (57%), while the proportion of oocytes arrested at MI was lower when cultured with dbcAMP (15%) than without dbcAMP (31%). The rate of monospermic fertilisation was higher when oocytes were cultured with dbcAMP (21%) than without dbcAMP (9%), with no difference in total penetration rates (58% and 52%, respectively). The blastocyst rate was higher in oocytes cultured with dbcAMP (32%) than without dbcAMP (19%). These results suggest that a change in intracellular level of cAMP during oocyte collection does not affect maturational and developmental competence of porcine oocytes and that synchronisation of meiotic maturation using dbcAMP enhances the meiotic potential of oocytes by promoting the MI to MII transition and results in high developmental competence by monospermic fertilisation.

Type
Research Article
Copyright
2003 Cambridge University Press

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