Varesi Sara, Vernocchi Valentina, Morselli Maria Giorgia, Luvoni Gaia Cecilia
Dipartimento di Scienze Veterinarie per la Salute, la Produzione Animale e la Sicurezza Alimentare - Università degli Studi di Milano, Via Celoria 10, 20133 Milano, Italy.
Reprod Biol. 2014 Dec;14(4):257-61. doi: 10.1016/j.repbio.2014.07.001. Epub 2014 Jul 17.
The aims of this study were to evaluate: (1) the effect of cryopreservation on DNA fragmentation of canine epididymal spermatozoa, and (2) the potential protective effect of melatonin on post-thaw sperm quality (motility, morphology, acrosomal and DNA integrity). Epididymal spermatozoa were collected after orchiectomy of ten dogs. Sperm samples were frozen in the presence or absence of melatonin (1mM). DNA fragmentation index (percentage of spermatozoa with fragmented DNA) was similar in fresh samples (3.3±3.6) and samples frozen with (4.2±3.8) or without (3.6±3.7) melatonin. Sperm motility was significantly (p<0.0001) higher in fresh compared to frozen samples. The presence of melatonin in the freezing extender did not affect the sperm motility. Proportions of spermatozoa with normal morphology were similar in fresh and frozen samples, irrespective of the presence of melatonin in the extender. Acrosome integrity was significantly decreased (p<0.01) by cryopreservation, and melatonin did not exert any beneficial effects. In conclusion, DNA fragmentation of canine epididymal spermatozoa was not affected by the freezing procedure, and the presence of melatonin did not preserve motility and acrosome integrity which were adversely affected by cryopreservation. The evaluation of DNA status of thawed gametes is particularly relevant for epididymal spermatozoa since these spermatozoa are usually stored and used in assisted reproductive techniques.
（1）冷冻保存对犬附睾精子DNA片段化的影响，以及（2）褪黑素对解冻后精子质量（活力、形态、顶体和DNA完整性）的潜在保护作用。在对10只犬进行睾丸切除术后收集附睾精子。精子样本在有或没有褪黑素（1mM）的情况下冷冻。新鲜样本（3.3±3.6）以及添加（4.2±3.8）或未添加（3.6±3.7）褪黑素冷冻的样本中，DNA片段化指数（DNA片段化精子的百分比）相似。与冷冻样本相比，新鲜样本中的精子活力显著更高（p<0.0001）。冷冻稀释液中褪黑素的存在不影响精子活力。无论稀释液中是否存在褪黑素，新鲜样本和冷冻样本中形态正常的精子比例相似。冷冻保存显著降低了顶体完整性（p<0.01），褪黑素未发挥任何有益作用。总之，犬附睾精子的DNA片段化不受冷冻程序的影响，褪黑素的存在也不能维持受冷冻保存不利影响的精子活力和顶体完整性。对于附睾精子而言，评估解冻配子的DNA状态尤为重要，因为这些精子通常用于辅助生殖技术并被储存。
