title: Cryotolerance of porcine blastocysts is improved by treating in vitro matured oocytes with L-carnitine prior to fertilization.
abstract: Sufficient generation of adenosine triphosphate (ATP) by oocytes is critical for fertilization and embryo development. The objective of this study was to determine the effects of supplementing media with L-carnitine, a co-factor required for the metabolism of fatty acids, during the peri-fertilization period on embryo development and energy generation. Firstly, in vitro matured (IVM) porcine oocytes were co-incubated with sperm in IVF medium supplemented with 0‒24 mM L-carnitine. The blastocyst formation rate of the control group was greater than those of the L-carnitine groups (P < 0.05), except for the 3 mM L-carnitine group. Subsequently, oocytes and/or sperm were treated without or with 3 mM L-carnitine for either the 1 h pre-IVF oocyte incubation; the pre-IVF sperm preparation; the first 30 min of IVF; or the entire 5.5 h of IVF. Despite similar fertilization rates among the groups, the cleavage rate of the pre-IVF oocyte group was significantly greater than those of the other groups, except for the pre-IVF sperm group. Additionally, the oocyte ATP content and the cryotolerance of the resulting blastocysts were examined following the pre-IVF oocyte treatment. Oocyte ATP content was also similar among the groups (P > 0.05). Following vitrification, the post-warming survival rate of blastocysts derived from L-carnitine-treated oocytes was greater than that of blastocysts derived from untreated oocytes (42.4% vs. 24.9%; P < 0.05). In conclusion, a 1 h oocyte exposure to 3 mM L-carnitine immediately prior to insemination enhanced cleavage and improved the cryotolerance of resulting blastocysts. While the findings are suggestive of a lipolytic action, further studies are required to clarify the contributions of lipid metabolism and oxidative mechanisms to the observed effects of the L-carnitine treatment.
authors.affiliation: Faculty of Veterinary Science, School of Life and Environmental Sciences, The University of Sydney, NSW 2570, Australia.
authors.forename: Jenna L
authors.initials: JL
authors.lastname: Lowe
authors.affiliation: Faculty of Veterinary Science, School of Life and Environmental Sciences, The University of Sydney, NSW 2570, Australia.
authors.forename: Louise K
authors.initials: LK
authors.lastname: Bartolac
authors.affiliation: Faculty of Veterinary Science, School of Life and Environmental Sciences, The University of Sydney, NSW 2570, Australia.
authors.forename: Roslyn
authors.initials: R
authors.lastname: Bathgate
authors.affiliation: Faculty of Veterinary Science, School of Life and Environmental Sciences, The University of Sydney, NSW 2570, Australia.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Grupen
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001755:Blastocyst / Q000187:drug effects*; D002331:Carnitine / Q000494:pharmacology*; D015925:Cryopreservation; D005260:Female; D005307:Fertilization in Vitro; D059471:In Vitro Oocyte Maturation Techniques; D008297:Male; D009865:Oocytes / Q000187:drug effects* / Q000378:metabolism; D013552:Swine; D058989:Vitrification / Q000187:drug effects*
chemical_list: D000255:Adenosine Triphosphate; D002331:Carnitine
keywords: In vitro fertilization (IVF); Lipid metabolism; Pig embryo; Vitrification