精胺抑制人精子的体外受精能力

以精子穿透去透明带仓鼠卵试验(SPA)为模型,评价了精胺对人精子体外受精能力的影响。精胺(0.25—8.0mmol/L)可抑制人精子体外获能和受精,其抑制作用与精胺浓度呈正相关,此种抑制作用是可逆的。用 HPLC 测定精子精胺含量表明,精子获能后精胺含量明显下降。dbcAMP(0.5—1.0mmol/L)或咖啡因(10mmol/L)可拮抗精胺抑制人精子体外获能。其拮抗作用随 dbcAMP 浓度而增强。钙离子载体 A 23187 2/μmol/L 或胰蛋白酶0.05%均可拮抗精胺抑制人精子穿卵率。上述结果提示,精胺可能通过降低精子 cAMP 含量和抑制钙内流或顶体酶活性,从而阻止人精子体外获能和受精。

SPERMINE INHIBITION OF IN VITRO FERTILIZING ABILITY OF HUMAN SPERMATOZOA AND ITS POSSIBLE MODE OF ACTION

The direct effect of spermine at various concentrations (0.25-8.0 mmol/L) on in vitro fertilizing ability of human spermatozoa was evaluated by the penetration test of zona-free hamster egg. To study the effect of spermine on capacitation, as judged by the rate of penetration, spermatozoa were incubated in BWW with various concentrations of spermine for 6 h at 37 degrees C. The hyperactivated motility of spermatozoa was markedly inhibited by spermine at a concentration of 4.0 mmol/L. The penetration rate was decreased proportionally to the dose of spermine used. Spermatozoa were incubated in BWW with 0.5 mmol/L spermine for 6 h and another 4 h after spermine was washed off with spermine-free BWW. The percentage of penetration was comparable to that of the control. Therefore, spermine-mediated inhibition of capacitation was reversible. Moreover, exogenous dbcAMP (0.5-1.0 mmol/L) or caffeine (10 mmol/L) could antagonize significantly the spermine-induced inhibition of capacitation with a correlation coefficient of 0.990. The content of spermine in fertile men spermatozoa was assayed by HPLC. Before capacitation spermine in spermatozoa was 7.05 micrograms/10(7) cells, whereas after capacitation it was no longer detectable, indicating that spermine may be an inhibitor of in vitro capacitation in human sperm. To study the effect of spermine on capacitated sperm, spermine was added to the BWW medium after sperm had been preincubated in spermine-free BWW. The persistent presence of spermine could interfere with spermatozoa attachment to, binding to and penetration into zona-free hamster eggs, which was related to the concentration (r = 0.820) used.(ABSTRACT TRUNCATED AT 250 WORDS)