Anderson R A, Feathergill K A, de Jonge C J, Mack S R, Zaneveld L J
Department of Obstetrics and Gynecology, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois.
J Androl. 1992 Sep-Oct;13(5):398-408.
The in vitro acrosome reaction of noncapacitated human spermatozoa was induced by both calcium ionophore (A23187) and dibutyryl adenosine cyclic monophosphate (Bu2cAMP), a membrane permeant cyclic nucleotide analog, in a dose-dependent manner. Maximal frequencies of acrosome-reacted spermatozoa above baseline values (12%; 90% confidence limits = 10.6 to 14.2%) were similar for Bu2cAMP and A23187 (24.5% and 25.1%, respectively). The concentration of Bu2cAMP required for a half-maximal response was 14.3 mumol/L, while that for A23187 was 24.5 pmol/L. The ability of A23187 to induce the acrosome reaction depended on the presence of calcium ion in the incubation medium. The A23187-induced reaction was prevented by the inclusion of human serum albumin in the medium; the inhibitory effect of albumin was partially reversed after preincubation of spermatozoa for 3 hours under capacitating conditions. In contrast, the Bu2cAMP-induced acrosome reaction was unaffected by either Ca2+ or albumin. Pulsed addition of Bu2cAMP enhanced the frequency of acrosome-reacted spermatozoa. This effect appeared to be influenced by pulse frequency: additions made every 5 minutes produced a greater maximal response than additions made every 2 minutes or every 15 minutes. The maximum theoretical acrosome reaction above baseline values (12%) was 88% of the total number of cells, accounting for almost the entire sperm population. Pulsed addition of A23187 did not increase the frequency of acrosome-reacted spermatozoa above values obtained from single equimolar additions of this agent. These data indicate that: (1) intracellular mechanisms for the human acrosome reaction are functional in noncapacitated spermatozoa; (2) the acrosome reaction can be separated from the process of capacitation; and (3) the acrosome reaction is affected by the pattern, as well as the type, of activation.
钙离子载体（A23187）和膜通透性环核苷酸类似物二丁酰腺苷环一磷酸（Bu2cAMP）均能以剂量依赖的方式诱导未获能的人类精子发生体外顶体反应。Bu2cAMP和A23187诱导的顶体反应精子的最大频率高于基线值（12%；90%置信区间=10.6%至14.2%），二者相似（分别为24.5%和25.1%）。产生半数最大反应所需的Bu2cAMP浓度为14.3μmol/L，而A23187为24.5 pmol/L。A23187诱导顶体反应的能力取决于孵育培养基中钙离子的存在。培养基中加入人血清白蛋白可阻止A23187诱导的反应；在获能条件下将精子预孵育3小时后，白蛋白的抑制作用部分逆转。相比之下，Bu2cAMP诱导的顶体反应不受Ca2+或白蛋白的影响。脉冲添加Bu2cAMP可提高顶体反应精子的频率。这种效应似乎受脉冲频率的影响：每5分钟添加一次产生的最大反应比每2分钟或每15分钟添加一次更大。高于基线值（12%）的最大理论顶体反应为细胞总数中的88%，几乎占整个精子群体。脉冲添加A23187并未使顶体反应精子的频率高于单次等摩尔添加该试剂所获得的值。这些数据表明：（1）人类顶体反应的细胞内机制在未获能的精子中起作用；（2）顶体反应可与获能过程分离；（3）顶体反应受激活模式以及激活类型的影响。
