Activation of GABAA receptor/Cl- channel and capacitation in rat spermatozoa: HCO3- and Cl- are essential.
This study was designed to determine whether HCO(3)(-) and Cl(-) are required for the activation of the GABA(A) receptor/Cl(-) channel (GBRC) by GABA and the subsequent capacitation of rat sperm. Spermatozoa from adult Sprague Dawley rats were incubated in four different media: modified complete rat fertilization medium (mRFM), Cl(-)-deficient (Cl(-)-DF) mRFM, HCO(3)(-)-DF mRFM, and Cl(-)-DF HCO(3)(-)-DF mRFM, with or without GBRC agonists (GABA and progesterone) or GBRC antagonists (bicuculline and picrotoxin) for 0-6 h under capacitating conditions. Sperm capacitation and hyperactivation were assessed by chlortetracycline staining and computer-assisted sperm analysis, respectively. The results showed that GABA added to the mRFM accelerated capacitation and hyperactivation, followed by increase in the acrosome reaction, reaching maximum value after 5 h. Progesterone also accelerated sperm capacitation and hyperactivation. Bicuculline and picrotoxin, antagonists of GABA, blocked the effects of both GABA and progesterone acceleration of sperm capacitation and hyperactivation. Sperm capacitation required both Cl(-) and HCO(3)(-). These results indicate that activation of GBRC may contribute to sperm capacitation and hyperactivation, and that both HCO(3)(-) and Cl(-) are essential. This is the first report of a close relationship between HCO(3)(-)/Cl(-) transport and the activation of GBRC in rat sperm capacitation and hyperactivation.
Jin
Jian-Yuan
JY
Unit of Reproductive Physiology, Zhejiang Academy of Medical Sciences, Hangzhou, Zhejiang, China.
Chen
Wen-Ying
WY
Zhou
Cheng Xi
CX
Chen
Zhang-Hui
ZH
Yu-Ying
Yuan
Y
Ni
Ya
Y
Chan
Hsiao Chang
HC
Shi
Qi-Xian
QX
D000818:Animals; D018118:Chloride Channels / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism; D058785:GABA-A Receptor Agonists; D008297:Male; D010472:Perchlorates / Q000378:metabolism*; D051381:Rats; D011963:Receptors, GABA-A / Q000378:metabolism*; D013075:Sperm Capacitation; D013094:Spermatozoa / Q000378:metabolism* / Q000502:physiology; D013194:Staining and Labeling
D018118:Chloride Channels; D002712:Chlorides; D058785:GABA-A Receptor Agonists; C062606:GABA-benzodiazepine receptor-chloride ionophore complex; D010472:Perchlorates; D011963:Receptors, GABA-A; C494474:perchlorate