GABA和孕酮对人及豚鼠精子的体外获能作用

为了探讨γ－氨基丁酸（ＧＡＢＡ）是否参与人及豚鼠精子体外获能的调节,将生育男子和豚鼠清子分别悬浮于ＢＷＷ和低Ｃａ＾２＋最小获能培养基（ＬＣａ＾２＋－ＭＣＭ）中,加入ＧＡＢＡ、孕酮（Ｐ４）、ＧＡＢＡＡ受体激动剂及其拮抗剂,在５％ＣＯ２孵箱３８．５℃培养２ｈ。然后用ｉｏｎｏｐｈｏｒｅ Ａ２３１８７激发精子顶体反应（ＡＲ）和超激活运动（ＨＡＭ）。以精子与金霉素（ＣＴＣ）荧光结合类型、ＡＲ和ＨＡＭ为指标来

Capacitating action of GABA and progesterone in spermatozoa of human and guinea pig in vitro

This study was designed to investigate whether GABA is involved in the capacitation effect and hyperactivated motility (HAM). Spematozoa from fertile men and retired guinea pigs were washed in modified BWW of 45% 90% Percoll gradient with 26 mg BSA/ml and in low Ca(2+)-MCM of 30%-55%-85% Percoll gradient (approximately 23 micromol/L Ca(2+)) respectively. The samples were preincubated for 2 h under 5% CO2 in air at 38.5 with or without GABA, progesterone (P(4)), GABA(A) receptor agonists or antagonists, and then exposed to 1 micromol/L (for human) or 5 micromol/L (for guinea pigs) calcium ionophore A 23187 for 15 min. The capacitation effect and HAM were assessed by using the chlortetracycline (CTC) staining method and phase-contrast microscopy. Motility was 80% 85% after all additions. The results showed that addition of GABA or P(4) at 5 micromol/L to the incubation medium resulted in a significant increase in the sum of B (characteristic of capacitated cell) and AR (acrosome recation) pattern (65.9% and 61.7% respectively), corresponding to capacitated spermatozoa in human, as compared to the control (37.3%). Likewise, the capacitating effect of GABA on spermatozoa in guinea pigs showed a concentration-dependent increase from 1 to 10 micromol/L(AR: 27.0 +/- 1.9% to 51.6 +/-2.8%). In addition, P(4) potentiated the capacitating effect of GABA when combined with GABA in the capacitation stage. The capacitating effect of GABA was mimicked by a GABAA receptor agonist muscimol. However, this effect was completely blocked by a GABA(A) receptor antagonist (-)-bicuculline and a GABA(A)/Cl(-) receptor antagonist picrotoxin. Furthermore, GABA markedly increased the HAM of P(4) on guinea pig spermatozoa, which was mediated obviously by the influx of extracellular Ca(2+) because the GABA-induced AR could be prevented by EGTA. These results indicate that GABA and P(4) are involved in the capacitation of spermatozoa in both human and guinea pigs through a GABA(A) receptor-mediated mechanism.