Storey Bayard T
Center for Research on Reproduction and Women's Health, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104-6142, USA.
Int J Dev Biol. 2008;52(5-6):427-37. doi: 10.1387/ijdb.072522bs.
Mammalian spermatozoa expend energy, generated as intracellular ATP, largely on motility. If the sperm cell cannot swim by use of its flagellar motion, it cannot fertilize the egg. Studies of the means by which this energy is generated span a period of six decades. This review gives an overview of these studies, which demonstrate that both mitochondrial oxidative phosphorylation, for which oxygen is friend, and glycolysis, for which sugar is friend, can provide the energy, independent of one another. In mouse sperm, glycolysis appears to be the dominant pathway; in bull sperm, oxidative phosphorylation is the predominant pathway. In the case of bull sperm, the high activity of the glycolytic pathway would maintain the intracellular pH too low to allow sperm capacitation; here sugar is enemy. The cow's oviduct has very low glucose concentration, thus allowing capacitation to go forward. The choice of the pathway of energy generation in vivo is set by the conditions in the oviduct of the conspecific female. The phospholipids of the sperm plasma membrane have a high content of polyunsaturated fatty acids represented in their acyl moieties, rendering them highly susceptible to lipid peroxidation; in this case oxygen is enemy. But the susceptibility of the sperm membrane to lethal damage by lipid peroxidation allows the female oviduct to dispose of sperm that have overstayed their welcome, and so keep in balance sperm access to the egg and sperm removal once this has occurred.
哺乳动物的精子消耗作为细胞内ATP产生的能量，主要用于运动。如果精子细胞不能通过鞭毛运动游动，就无法使卵子受精。关于产生这种能量的方式的研究跨越了六十年。这篇综述概述了这些研究，这些研究表明，线粒体氧化磷酸化（氧气是其“朋友”）和糖酵解（糖是其“朋友”）都可以相互独立地提供能量。在小鼠精子中，糖酵解似乎是主要途径；在公牛精子中，氧化磷酸化是主要途径。就公牛精子而言，糖酵解途径的高活性会使细胞内pH值过低，从而无法使精子获能；在这里糖是“敌人”。母牛的输卵管葡萄糖浓度非常低，因此可以使获能过程顺利进行。体内能量产生途径的选择由同种雌性输卵管中的条件决定。精子质膜的磷脂在其酰基部分含有高含量的多不饱和脂肪酸，使其极易发生脂质过氧化；在这种情况下氧气是“敌人”。但是精子膜对脂质过氧化造成的致命损伤的敏感性使雌性输卵管能够处理停留时间过长不受欢迎的精子，从而在精子接近卵子以及精子完成受精后被清除之间保持平衡。
