Ginsenoside Re promotes human sperm capacitation through nitric oxide-dependent pathway.

The regulation of sperm capaci- tation is important for successful fertilization. Ginseno- sides, the biologically effective components of ginseng, have been found to enhance intracellular nitric oxide (NO) production and the latter has recently been indicated to play a significant role in modulation of sperm functions. We investigated the effect of Ginseno- side Re on human sperm capacitation in vitro and the mechanism by which the Ginsenosides play their roles. Spermatozoa were separated by Percoll and incubated with 0, 1, 10, or 100 mM of Ginsenoside Re. The percentages of spontaneous and lysophosphatidylcho- line (LPC)-induced acrosome reaction (AR), as a measure of sperm capacitation, were assayed with fluorescein isothiocyanate-conjugated Pisum sativum agglutinin (FITC-PSA). The intracellular cGMP level was measured by ( 3 H) cGMP radioimmunoassay system. The results showed that the percentages of both spontaneous and LPC-induced AR and intracel- lular cGMP level were significantly enhanced by Ginsenoside Re with a concentration-dependent man- ner. Sodium nitroprusside (SNP, 100 nM), a NO donor, mimicked the effects of Ginsenoside Re. And pretreatment with a NOS inhibitor N o -nitro-L-arginine methyl ester (L-NAME, 100 mM) or a NO scavenger N-acetyl-L-cysteine (LNAC, 1 mM) completely blocked the effects of Ginsenoside Re. Furthermore, the AR- inducing effect of Ginsenoside Re was significantly reduced in the presence of the soluble guanylate cyclase inhibitor LY83583 or cGMP-dependent protein kinase (PCK) inhibitor KT5823, whereas addition of the cGMP analogue 8-Br-cGMP significantly increased the AR of human spermatozoa. Data suggested that Ginsenoside Re is beneficial to sperm capacitation and AR, and that the effect is accomplished through NO/ cGMP/PKG pathway. Mol. Reprod. Dev. 74: 497- 501, 2007. 2006 Wiley-Liss, Inc.