The Robinson Institute, Research Centre for Reproductive Health, School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, SA 5005, Australia.
Theriogenology. 2012 May;77(8):1632-41. doi: 10.1016/j.theriogenology.2011.12.008. Epub 2012 Feb 25.
Although current embryo culture media are based on carbohydrate metabolism of embryos, little is known about metabolism of endogenous lipids. L-carnitine is a β-oxidation cofactor absent in most culture media. The objective was to investigate the influence of L-carnitine supplementation on bovine embryo development. Abattoir-derived bovine cumulus oocyte complexes were cultured and fertilized. Post-fertilization, presumptive zygotes were transferred into a basic cleavage medium ± carbohydrates (glucose, lactate and pyruvate) ± 5 mm L-carnitine and cultured for 4 days in vitro. In the absence of carbohydrates during culture, embryos arrested at the 2- and 4-cell stages. Remarkably, +L-carnitine increased development to the morula stage compared to +carbohydrates alone (P < 0.001). The beneficial effects of L-carnitine were further demonstrated by inclusion of carbohydrates, with 14-fold more embryos reaching the morula stage after culture in the +carbohydrates +L-carnitine group compared to the +carbohydrates group (P < 0.05). Whereas there was a trend for +L-carnitine to increase ATP (P = 0.09), ADP levels were higher and ATP: ADP ratio were 1.9-fold lower (main effect, P < 0.05) compared to embryos cultured in -L-carnitine. Therefore, we inferred that +L-carnitine embryos were more metabolically active, with higher rates of ATP-ADP conversion. In conclusion, L-carnitine supplementation supported precompaction embryo development and there was an additive effect of +L-carnitine +carbohydrates on early embryo development, most likely through increased β-oxidation within embryos.
虽然当前的胚胎培养液基于胚胎的碳水化合物代谢，但对于内源性脂质代谢知之甚少。左旋肉碱是大多数培养物中缺乏的β-氧化辅助因子。本研究旨在探讨左旋肉碱补充对牛胚胎发育的影响。从屠宰场获得牛卵丘-卵母细胞复合物并进行培养和受精。受精后，将胚胎转移到基本的卵裂培养液中，添加碳水化合物（葡萄糖、乳酸盐和丙酮酸盐）±5mm 左旋肉碱，并在体外培养 4 天。在培养过程中不添加碳水化合物时，胚胎停滞在 2-和 4-细胞阶段。值得注意的是，与仅添加碳水化合物相比，添加左旋肉碱可显著增加胚胎发育到桑椹胚阶段（P < 0.001）。在添加碳水化合物的情况下，左旋肉碱的有益作用进一步得到证实，与添加碳水化合物组相比，添加碳水化合物+左旋肉碱组中 14 倍以上的胚胎达到桑椹胚阶段（P < 0.05）。尽管添加左旋肉碱有增加 ATP 的趋势（P = 0.09），但 ADP 水平更高，ATP:ADP 比值降低了 1.9 倍（主要效应，P < 0.05）与在无左旋肉碱培养液中培养的胚胎相比。因此，我们推断添加左旋肉碱的胚胎具有更高的代谢活性，具有更高的 ATP-ADP 转换率。总之，左旋肉碱补充支持预浓缩胚胎发育，并且添加左旋肉碱+碳水化合物对早期胚胎发育具有附加效应，这可能是通过胚胎内β-氧化的增加实现的。
