Laboratory of Equine Reproduction, Faculty of Veterinary Medicine, Veterinary Teaching Hospital, University of Extremadura, Cáceres, Spain.
J Pineal Res. 2011 Sep;51(2):172-9. doi: 10.1111/j.1600-079X.2011.00873.x. Epub 2011 Apr 12.
Lipid peroxidation (LPO) has been claimed as a major factor involved in stallion damage during storage or cryopreservation. Because melatonin is a well-known potent antioxidant, the aim of the present study was to investigate the effect of melatonin during in vitro incubation. Furthermore, we investigated the presence of specific melatonin receptors (MT1 and MT2) using specific polyclonal antibodies and western blotting. Stallion spermatozoa were incubated up to 3 hr at 37°C in the presence of different concentrations of melatonin (0, 50 pm, 100 pm, 200 pm, or 1 μm). At the beginning and at the end of the incubation period, sperm motility (using computer-assisted sperm analysis), membrane integrity and permeability, fluidity of the sperm membrane, LPO, and mitochondrial membrane potential (Δψm) were flow cytometrically evaluated. Melatonin reduced changes in the spermatozoa related to apoptosis (increased sperm membrane permeability and lowered Δψm) (P < 0.05). Furthermore, LPO was dramatically reduced (P < 0.01) while no effect was observed on sperm motility or kinematics. Interestingly, melatonin helped maintain a more fluid sperm plasmalemma (P < 0.05). Our results clearly show the absence of MT1 and MT2 receptors in the stallion spermatozoa. It is concluded that melatonin is a useful tool to improve the quality of stored stallion sperm, increasing their life span and reducing premature aging, this likely relates to melatonin's antioxidant properties.
脂质过氧化（LPO）被认为是在储存或冷冻保存过程中导致种马损伤的主要因素。由于褪黑素是一种众所周知的强效抗氧化剂，本研究的目的是在体外孵育期间研究褪黑素的作用。此外，我们使用特异性多克隆抗体和 Western blot 法研究了特定的褪黑素受体（MT1 和 MT2）的存在。将种马精子在 37°C 下孵育长达 3 小时，同时存在不同浓度的褪黑素（0、50 pm、100 pm、200 pm 或 1 μm）。在孵育期开始和结束时，使用计算机辅助精子分析评估精子运动性、膜完整性和通透性、精子膜流动性、LPO 和线粒体膜电位（Δψm）。褪黑素降低了与凋亡相关的精子变化（增加精子膜通透性和降低Δψm）（P<0.05）。此外，LPO 显著降低（P<0.01），而对精子运动性或运动学没有影响。有趣的是，褪黑素有助于维持更具流动性的精子质膜（P<0.05）。我们的结果清楚地表明，在种马精子中不存在 MT1 和 MT2 受体。因此，可以得出结论，褪黑素是一种有用的工具，可以提高储存种马精子的质量，延长其寿命并减少过早衰老，这可能与褪黑素的抗氧化特性有关。
