title: Supplementation of culture medium with L-carnitine improves development and cryotolerance of bovine embryos produced in vitro.
abstract: High lipid content in embryos is associated with low freezing tolerance. This study assessed the effects of exogenous L-carnitine, an enhancer of lipid metabolism, on the in vitro development and freezing survival of bovine embryos. Also, effects on metabolic activity, reactive oxygen species (ROS) and apoptosis were investigated. Supplementation of embryo culture medium with 1.518 mM or 3.030 mM L-carnitine significantly increased the rates of zygote development to the blastocyst stage and blastocyst cell numbers whereas 6.072 mM of this compound did not improve embryo development. Survival rates after slow freezing of blastocysts were significantly higher when embryos were cultured in the presence of 1.518 mM or 3.030 mM L-carnitine compared with the control. A lower density of lipid droplets was detected in L-carnitine-treated blastocysts compared with the control. L-carnitine significantly reduced ROS levels in 2-cell embryos but did not reduce ROS levels at later stages. The apoptotic cell rate was not different between control and L-carnitine-treated blastocysts. L-carnitine significantly increased ATP levels in 2-cell embryos but not at the 8-cell or blastocyst stages. L-carnitine increased the expression of metabolism-related ATP6 and COX1 genes in blastocysts. In conclusion, L-carnitine supplementation enhanced lipid metabolism in embryos resulting in improved development and cryotolerance of bovine blastocysts produced in vitro.
authors.affiliation: NARO Institute of Livestock and Grassland Science, Ikenodai 2, Tsukuba, Ibaraki 305-0901, Japan.
authors.forename: Toshikiyo
authors.initials: T
authors.lastname: Takahashi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Inaba
authors.forename: Tamas
authors.initials: T
authors.lastname: Somfai
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kaneda
authors.forename: Masaya
authors.initials: M
authors.lastname: Geshi
authors.forename: Takashi
authors.initials: T
authors.lastname: Nagai
authors.forename: Noboru
authors.initials: N
authors.lastname: Manabe
mesh_terms: D000064:Acclimatization / Q000187:drug effects*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002331:Carnitine / Q000494:pharmacology*; D002417:Cattle; D003470:Culture Media / Q000737:chemistry*; D046149:Embryo Culture Techniques / Q000379:methods; D004622:Embryo, Mammalian / Q000187:drug effects / Q000502:physiology*; D047108:Embryonic Development / Q000187:drug effects*; D004734:Energy Metabolism / Q000187:drug effects; D005615:Freezing; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D050356:Lipid Metabolism / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D003470:Culture Media; D017382:Reactive Oxygen Species; D000255:Adenosine Triphosphate; D002331:Carnitine