Gavella M, Lipovac V
Vuk Vrhovac Institute, University Clinic for Diabetes, Endocrinology and Metabolic Diseases, Medical Faculty University of Zagreb, Croatia.
Arch Androl. 2000 Jan-Feb;44(1):23-7. doi: 10.1080/014850100262371.
The ability of melatonin to suppress experimentally induced lipid peroxidation (LPO) in sperm membrane was investigated in 41 samples of infertile men. Iron/ascorbate (0.04/0.2 mmol)-induced LPO was measured by the formation of malondialdehyde (MDA) using the thiobarbituric acid method. Sperm incubated in the presence of melatonin (2-6 mmol) exhibited a concentration-dependent decrease of MDA generated from hydroperoxide of the sperm plasma membrane in the presence of promoter system. Addition of 6 mmol of melatonin significantly reduced the rate of lipid peroxidation in sperm of unselected donors (mean +/- SE in control samples = 26.4 +/- 2.9 vs. 6.5 +/- 1.1 nmol MDA/10(8) sperm in melatonin-treated samples: n = 16, p < .005). Inhibitory effect of melatonin was also significant in the presence of 0.015 mmol of ferrous ions (20.5 +/- 1.7 vs. 7.9 +/- 1.6 nmol MDA/10(8) sperm in melatonin-treated samples: n = 7, p < .02) and (.005 mmol of ferrous ions (20.2 +/- 2.8 vs. 9.9 +/- 2.4 nmol MDA/ 10(8) sperm: n = 6, p < .05). Comparing the effect of melatonin with that of Trolox, an analog of vitamin E. a similar effect at concentration of 0.1-0.2 mmol of Trolox was found (25.2 +/- 2.9 vs. 11.8 +/- 1.2 nmol MDA/10(8) sperm in Trolox-treated samples: n = 7, p < .005). The obtained data of in vitro experiments show that melatonin is 40-fold less efficient than Trolox in achieving the 50% reduction in LPO (4 vs. 0.1 mmol). Since the physiological concentration of melatonin in human semen is at the nanomolar level, its antioxidative role in vivo is probably of minor importance.
在41例不育男性样本中研究了褪黑素抑制精子膜实验性诱导脂质过氧化（LPO）的能力。采用硫代巴比妥酸法通过丙二醛（MDA）的形成来测定铁/抗坏血酸（0.04/0.2 mmol）诱导的LPO。在启动子系统存在的情况下，在褪黑素（2 - 6 mmol）存在下孵育的精子表现出精子质膜氢过氧化物产生的MDA呈浓度依赖性降低。添加6 mmol褪黑素可显著降低未选择供体精子中的脂质过氧化速率（对照样本中平均值±标准误 = 26.4 ± 2.9 vs. 褪黑素处理样本中6.5 ± 1.1 nmol MDA/10⁸精子：n = 16，p <.005）。在存在0.015 mmol亚铁离子时，褪黑素的抑制作用也很显著（褪黑素处理样本中20.5 ± 1.7 vs. 7.9 ± 1.6 nmol MDA/10⁸精子：n = 7，p <.02）以及存在0.005 mmol亚铁离子时（20.2 ± 2.8 vs. 9.9 ± 2.4 nmol MDA/10⁸精子：n = 6，p <. .05）。将褪黑素的作用与维生素E类似物Trolox的作用进行比较，发现在0.1 - 0.2 mmol浓度的Trolox时有类似作用（Trolox处理样本中25.2 ± 2.9 vs. 11.8 ± 1.2 nmol MDA/10⁸精子：n = 7，p <.005）。体外实验获得的数据表明，在使LPO降低50%方面，褪黑素的效率比Trolox低40倍（4 vs. 0.1 mmol）。由于人精液中褪黑素的生理浓度处于纳摩尔水平，其在体内的抗氧化作用可能不太重要。
