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.

Cl- is required for HCO3- entry necessary for sperm capacitation in guinea pig: involvement of a Cl-/HCO3- exchanger (SLC26A3) and CFTR.

Our previous study demonstrated the involvement of cystic fibrosis transmembrane conductance regulator (CFTR) in transporting bicarbonate that is necessary for sperm capacitation; however, whether its involvement is direct or indirect remains unclear. The present study investigated the possibility of a Cl-/HCO3- exchanger (solute carrier family 26, number 3 [SLC26A3]) operating with CFTR during guinea pig sperm capacitation. Incubating sperm in media with various concentrations of Cl- resulted in varied percentages of capacitated sperm in a concentration-dependent manner.

Cystic fibrosis transmembrane conductance regulator is vital to sperm fertilizing capacity and male fertility.

Cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel, mutations of which cause cystic fibrosis, a disease characterized by defective Cl(-) and HCO(3)(-) transport. Although >95% of all CF male patients are infertile because of congenital bilateral absence of the vas deferens (CBAVD), the question whether CFTR mutations are involved in other forms of male infertility is under intense debates. Here we report that CFTR is detected in both human and mouse sperm.

Critical role of CFTR in uterine bicarbonate secretion and the fertilizing capacity of sperm.

Cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-activated Cl- channel expressed in a wide variety of epithelial cells, mutations of which are responsible for hallmark defective Cl- and HCO3- secretion seen in cystic fibrosis (CF). However, the physiological role of CFTR in reproductive tracts is far from understood although infertility has been observed in CF patients of both sexes. Previously we have demonstrated the expression of CFTR in the female reproductive tract and the involvement of CFTR in mediating anion secretion by the endometrium.

[Immunogenicity of recombinant human zona pellucida-3 peptides expressed in E. coli and efficacy of their antisera to inhibit in vitro human sperm-egg binding].

The present study was aimed to analyze the immunogenicity of recombinant human zona pellucida-3 peptides (r-huZP3a(22 approximately 176) and r-huZP3b(177 approximately 348)) expressed in E. coli through immunizing rabbits, and to evaluate the efficacy of their polyclonal antisera against r-huZP3a(22 approximately 176) and r-huZP3b(177 approximately 348) to inhibit in vitro human sperm-egg binding respectively. Male New Zealand rabbits were immunized using r-huZP3a(22 approximately 176) or r-huZP3b(177 approximately 348) as antigen respectively, which was purified through an improved method of preparative gel polyacryulamide gel electrophoresis.

GABA, progesterone and zona pellucida activation of PLA2 and regulation by MEK-ERK1/2 during acrosomal exocytosis in guinea pig spermatozoa.

We investigated whether GABA activates phospholipase A2 (PLA2) during acrosomal exocytosis, and if the MEK-ERK1/2 pathway modulates PLA2 activation initiated by GABA, progesterone or zona pellucida (ZP). In guinea pig spermatozoa prelabelled with [14C]arachidonic acid or [14C]choline chloride, GABA stimulated a decrease in phosphatidylcholine (PC), and release of arachidonic acid and lysoPC, during exocytosis. These lipid changes are indicative of PLA2 activation and appear essential for exocytosis since inclusion of aristolochic acid (a PLA2 inhibitor) abrogated them, along with exocytosis.

Involvement of CFTR in uterine bicarbonate secretion and the fertilizing capacity of sperm.

Cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-activated chloride channel expressed in a wide variety of epithelial cells, mutations of which are responsible for the hallmark defective chloride secretion observed in cystic fibrosis (CF). Although CFTR has been implicated in bicarbonate secretion, its ability to directly mediate bicarbonate secretion of any physiological significance has not been shown. We demonstrate here that endometrial epithelial cells possess a CFTR-mediated bicarbonate transport mechanism.