γ-氨基丁酸诱发人精子顶体反应及其受精能力

GABA INITIATES THE ACROSOME REACTION AND FERTILIZING ABILITY IN HUMAN SPERM

本文的目的是为了探讨γ-氨基丁酸（GABA）是否可激发人精子顶体反应（AR）。受精能力及其可能的作用方式。实验采用金霉素荧光染色法（CFC）、胞内游离Ca2＋测定和精子穿透去透明带仓鼠卵（SPA）试验，分别评价GABA诱发人精子AR及其穿卵能力。结果表明：CABA可诱发人获能精子发生AR，且随精子获能进程而显著增加，并存在明显的量效关系，该作用可被P4加强。GABA还可明显地激发胞内钙［Ca2＋］i升高。然而，GABA诱发精子AR不仅可被Ca2＋螫合剂EGTA所桔抗，而且为Ca2＋通道阻滞剂La3＋所阻断。此外，GABA还可明显地促进人精子的穿卵能力。据此推论，GABA通过Ca2＋介导，调节人精子AN，促进受精率提高。上述结果为激活精子表而GABAA受体及其引起信息传递的研究奠定了基础。

The present study was undertaken to investigate whether GABA induced the acrosome reaction (AR) and fertilizing ability, as well as its POssible mode of action in human spermatozoa. Spermatozoa from fifteen health fertile men isolated by the swim-up techniqUe were preincubated in a modified Bac with 0.35% BSA for 1-11 h under 5% CO2 in 95% air at 37℃. Aliquots of spermatozoa were collected at 0, 1, 3, 5,7, 9 and 11 h of incubation for evaluation of foe AR by chlortetracycline (CTC)staining. The sperm penetration assay (SPA) was carried out by using the zona-free hamster oocyte test. Intracellulax calcium ([ Ca2+ ]i ) concentrations were detendned by means of fluorescent probe Frua-2/AM. GABA at 1 .25 Umol/L significantly induced the AR in human spermatozoa preincubated for 3 h, with a maximal response in preincubated for 9 h, and the effect changed in a concentration- dependent manner. The maximal stimulatory effect was observed with 1.25 wmoaL GABA, and the AR then decreased markedly with further increase of GABA concentration to 10 wmoaL. EXPosure of preincubated spermatozoa to GABA in combination with progesterone resulted in a higher proportion of the AR as compared with that obtained with each agonist applied alone. In addition, GABA prompted a rapid increase in interacellular [ Ca2+ ]i. Furthermore, the AR indllced by GABA was prevented by inclusion of 1 rrirnoUL EGTA or 100 wmoaL aam +. also, GABA enhanced significantly the ability of spermatozoa penetrating zona-free harnster oocytes and the index of fertilization. These results indicate that GABA may be involved in the modulation of the AR and the fertilization process in capacitated human sperfnatozoa thlough a calcium mediated mechanism, thus opening up posibilities for studies of signal transductions thlough activation of the GABAA receptor present on the sperm surface.