College of Veterinary Medicine, Kangwon National University, Chuncheon, Korea.
Theriogenology. 2012 Jul 15;78(2):235-43. doi: 10.1016/j.theriogenology.2012.02.027. Epub 2012 May 11.
The objective of this study was to examine the effect of L-carnitine treatment during in vitro maturation (IVM) of immature pig (Sus scrofa) oocytes. Specifically, the effects of L-carnitine treatment on nuclear maturation and oocyte intracellular glutathione (GSH) levels, embryonic development after parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT), and gene expression levels in SCNT pig embryos were determined. During IVM culture, immature oocytes were either treated or not treated with 10 mM L-carnitine. L-carnitine treatment did not improve the nuclear maturation of oocytes but significantly increased intracellular GSH levels, which led to a reduction of reactive oxygen species (ROS) levels in IVM oocytes. Oocytes treated with L-carnitine showed higher (P<0.05) rates of blastocyst formation after PA (39.4% vs. 27.1%) and SCNT (23.2% vs. 14.9%) compared with untreated oocytes. SCNT embryos that were derived from L-carnitine-treated oocytes showed increased (P<0.05) expression levels of DNMT1, PCNA, FGFR2, and POU5F1 mRNA compared with control embryos. Treatment of recipient oocytes with L-carnitine increased (P<0.05) the expression of both BAX and p-Bcl-xl mRNA in SCNT blastocysts. However, the increase was more prominent in BAX than in p-Bcl-xl mRNA. Our results demonstrate that L-carnitine treatment during IVM improves the developmental competence of SCNT embryos. This effect is probably due to increased intracellular GSH synthesis in recipient ooplasts, which reduces ROS levels, and the stimulation of nuclear reprogramming via increased expression of POU5F1 and transcription factors.
本研究旨在探讨左旋肉碱（L-carnitine）在猪卵母细胞体外成熟（IVM）过程中的作用。具体而言，研究了 L-carnitine 处理对核成熟、卵母细胞内谷胱甘肽（GSH）水平、孤雌激活（PA）和体细胞核移植（SCNT）后胚胎发育以及 SCNT 猪胚胎基因表达水平的影响。在 IVM 培养过程中，将不成熟的卵母细胞分为未处理组和 10mM L-carnitine 处理组。L-carnitine 处理并未提高卵母细胞的核成熟率，但显著增加了细胞内 GSH 水平，从而降低了 IVM 卵母细胞中的活性氧（ROS）水平。与未处理组相比，经 L-carnitine 处理的卵母细胞在 PA（39.4%比 27.1%）和 SCNT（23.2%比 14.9%）后形成囊胚的比例更高（P<0.05）。与对照组胚胎相比，来自 L-carnitine 处理卵母细胞的 SCNT 胚胎中 DNMT1、PCNA、FGFR2 和 POU5F1 mRNA 的表达水平增加（P<0.05）。用 L-carnitine 处理受体卵母细胞增加了 SCNT 囊胚中 BAX 和 p-Bcl-xl mRNA 的表达（P<0.05）。然而，BAX mRNA 的增加比 p-Bcl-xl mRNA 更为显著。本研究结果表明，IVM 期间 L-carnitine 处理可提高 SCNT 胚胎的发育能力。这种作用可能归因于受体卵母细胞内 GSH 合成的增加，从而降低了 ROS 水平，并通过 POU5F1 和转录因子表达的增加刺激核重编程。
