Acetylcholine causes an increase of intracellular calcium in human sperm
Acetylcholine causes an increase of intracellular calcium in human sperm
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DOI：
10.1093/molehr/gah245
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发表时间：
2005-12-01
影响因子：
4
通讯作者：
Meizel, S
中科院分区：
文献类型：
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作者：
Bray, C;Son, JH;Meizel, S
精子烟碱乙酰胆碱受体（nAChRs）可以影响精子的运动和顶体反应（AR）的启动。我们报道乙酰胆碱（ACh）在有能力的人类精子中启动AR需要外部介质中的Na+和Ca2+。用50 μ M 3-喹啉苄基苯甲酸酯（QNB）或50 nM士的宁预孵育不能抑制乙酰胆碱引发的AR，这表明含有α 9亚基的毒蕈碱achr和nachr不能介导这一事件。胆碱（2.5、5和10 mM）是一种高特异性但低效力的α - 7 nAChR引发的AR激动剂，其作用被nAChR拮抗剂甲基lycaconitine （MLA）阻断。ACh （50-400 μ M）刺激了携带FURA-2的精子群体细胞内Ca2+的短暂小幅上升，其中200 μ M ACh最大（146 nM +/- 23 SEM）。nAChR拮抗剂，α -bungarotoxin （α - btx）和MLA，分别减少了75%和78%的ach启动的Ca2+上升，表明大部分的上升是通过含有α 7或α 9亚基的nAChR介导的。使用FLUO-3的单细胞成像研究解决了两种模式的ach刺激Ca2+在精子头部增加：94%的响应精子显示上升（59.6% +/- 5.7 SEM从静息荧光强度增加），在2-3分钟内恢复到静息水平。剩余的精子（6%）显示出Ca2+的急剧峰值（类似于1分钟；86% +/- 4.3扫描电镜荧光强度变化），随后荧光突然丧失，提示AR的模式。精子中部的Ca2+内流似乎伴随着头部的Ca2+内流。这些观察结果证实了nachr在精子功能中的离子化作用。
Sperm nicotinic acetylcholine receptors (nAChRs) can influence motility and the initiation of acrosome reaction (AR). We report that AR initiation by acetylcholine (ACh) in capacitated human sperm requires both Na+ and Ca2+ in the external medium. Pre-incubation with 50 mu M 3-quinuclidinyl benzilate (QNB) or 50 nM strychnine failed to inhibit the ACh-initiated AR, demonstrating that muscarinic AChRs and nAChRs containing alpha 9 subunits do not mediate this event. Choline (2.5, 5 and 10 mM), a highly specific but low potency agonist of the alpha 7 nAChR initiated AR, with its effect blocked by the nAChR antagonist methyllycaconitine (MLA). ACh (50-400 mu M) stimulated a small transient rise in the intracellular Ca2+ in sperm populations loaded with FURA-2, with 200 mu M ACh being maximal (146 nM +/- 23 SEM). The nAChR antagonists, alpha-bungarotoxin (alpha-BTX) and MLA, reduced the ACh-initiated Ca2+ rise by 75 and 78%, respectively, demonstrating the majority of the rise is mediated through nAChRs containing alpha 7 or alpha 9 subunits. Single cell imaging studies using FLUO-3 resolved two patterns of ACh-stimulated Ca2+ increase in the sperm head: 94% of responding sperm displayed a rise (59.6% +/- 5.7 SEM increase from resting fluorescence intensity), returning to resting levels over a period of 2-3 min. The remaining sperm (6%) displayed a sharp spike of Ca2+ (similar to 1 min; 86% +/- 4.3 SEM change in fluorescence intensity), followed by abrupt loss of fluorescence, a pattern suggestive of AR. A Ca2+ influx in the sperm midpiece appeared to accompany the Ca2+ influx seen in the head. These observations confirm an ionotropic role for nAChRs in sperm function.