Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
Biol Reprod. 2013 Jun 27;88(6):164. doi: 10.1095/biolreprod.112.106062. Print 2013 Jun.
Metabolic conditions characterized by elevated free fatty acid concentrations in blood and follicular fluid are often associated with impaired female fertility. Especially elevated saturated fatty acid levels can be lipotoxic for several somatic cell types. The aim of this study was to determine the impact of elevated free fatty acid concentrations in follicular fluid on neutral lipids (fatty acids stored in lipid droplets) inside cumulus cells and oocytes and their developmental competence. To this end, cows were exposed to a short-term fasting period during final oocyte maturation. This resulted in elevated, but distinct, free fatty acid concentrations in blood and follicular fluid and a rise in the concentrations of in particular fatty acids with a chain length of 14-18 carbon atoms. Interestingly, elevated free fatty acid concentrations in follicular fluid resulted in a massive increase in the level of neutral lipids in cumulus cells, whereas the level of neutral lipid in oocytes was hardly affected. Furthermore, competence of oocytes to develop to the blastocyst stage after fertilization and culture of cumulus-oocyte-complexes of the experimental and control group was not different. In conclusion these data suggest that short-term elevated free fatty acid concentrations in follicular fluid do not harm oocyte developmental competence. We propose that the involvement of high levels of mobilized oleic acid in follicular fluid in combination with the induced lipid storage in cumulus cells serves to prevent harmful saturated fatty acid exposure to the oocyte.
血液和卵泡液中游离脂肪酸浓度升高的代谢状况常与女性生育力受损有关。特别是饱和脂肪酸水平升高，可能对几种体细胞类型具有脂毒性。本研究旨在确定卵泡液中游离脂肪酸浓度升高对卵丘细胞和卵母细胞内中性脂质（储存在脂滴中的脂肪酸）及其发育能力的影响。为此，奶牛在卵母细胞最后成熟期间经历了短期禁食。这导致血液和卵泡液中游离脂肪酸浓度升高，但明显升高，特别是具有 14-18 个碳原子链长的脂肪酸浓度升高。有趣的是，卵泡液中游离脂肪酸浓度升高导致卵丘细胞中中性脂质水平大量增加，而卵母细胞中的中性脂质水平几乎没有受到影响。此外，实验组和对照组卵丘-卵母细胞复合物受精和培养后胚胎发育至囊胚阶段的能力没有差异。总之，这些数据表明，卵泡液中短期游离脂肪酸浓度升高不会损害卵母细胞的发育能力。我们提出，卵泡液中高水平的游离油酸的参与以及卵丘细胞中诱导的脂质储存，有助于防止卵母细胞受到有害的饱和脂肪酸暴露。
