Pre-maturation with cAMP modulators in conjunction with EGF-like peptides during in vitro maturation enhances mouse oocyte developmental competence.
Recent studies have independently shown that cyclic adenosine 3'5'-monophosphate (cAMP) modulation prior to in vitro maturation (IVM) and epidermal growth factor (EGF)-like peptide supplementation during IVM improve subsequent oocyte developmental outcomes. This study investigated the effects of an IVM system that incorporates these two concepts. Cumulus-oocyte complexes (COCs) were collected from pre-pubertal mice either 46 hr post-equine chorionic gonadotropin (eCG) (IVM) or post-eCG + post-human chorionic gonadotropin (hCG) stimulation (in vivo maturation; IVV). IVM COCs were treated with the cAMP modulators forskolin and IBMX for 1, 2, or 4 hr (pre-IVM phase) prior to IVM. COCs then underwent IVM with the EGF-like peptides amphiregulin or epiregulin, or with the common IVM stimulants follicle-stimulating hormone (FSH) or EGF. A pre-IVM phase increased the size of the subsequent blastocysts' inner-cell-mass compared to standard IVM, regardless of IVM treatment (P < 0.05). Unlike FSH or EGF, amphiregulin or epiregulin significantly increased blastocyst quality (trophectoderm and total cell numbers) and/or yield (P < 0.01) compared to standard IVM, and were the only treatments that produced blastocysts comparable to IVV-derived blastocysts. Forskolin acutely up-regulated EGF-like peptide mRNA expression after a 2-hr pre-IVM phase (P < 0.001), although EGF receptor and ERK1/2 activities were not significantly different than control. IVV-like levels of EGF-like peptide mRNA expression during IVM were maintained only by supplementing with EGF-like peptides and EGF, since expression levels induced by FSH were significantly lower in vitro than during IVV. However, EGF receptor and ERK1/2 phosphorylation levels were not significantly different across treatment groups. In conclusion, a pre-IVM phase in conjunction with IVM in the presence of EGF-like peptides endows high oocyte developmental competence, as evidenced by increased embryo yield and/or quality relative to FSH and EGF.
Faculty of Health Sciences, Discipline of Obstetrics and Gynaecology, The Robinson Institute, Research Centre for Reproductive Health, School of Paediatrics and Reproductive Health, The University of Adelaide, Adelaide, Australia.
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D
Richani
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Wang
H T
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Zeng
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Smitz
J G
JG
Thompson
R B
RB
Gilchrist
D066258:Amphiregulin; D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000378:metabolism; D054885:Cumulus Cells / Q000166:cytology / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism*; D066255:EGF Family of Proteins / Q000378:metabolism*; D066260:Epiregulin / Q000378:metabolism*; D005260:Female; D006801:Humans; D059471:In Vitro Oocyte Maturation Techniques; D020935:MAP Kinase Signaling System / Q000502:physiology; D051379:Mice; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*
D066258:Amphiregulin; C587849:Areg protein, mouse; D066255:EGF Family of Proteins; D066260:Epiregulin; C587881:Ereg protein, mouse; D000242:Cyclic AMP