Acrosome reaction in the cumulus oophorus revisited: involvement of a novel sperm-released factor NYD-SP8

Fertilization is a process involving multiple steps that lead to the final fusion of one sperm and the oocyte to form the zygote. One of the steps, acrosome reaction (AR), is an exocytosis process, during which the outer acrosome membrane fuses with the inner sperm membrane, leading to the release of acrosome enzymes that facilitate sperm penetration of the egg investments. Though AR has been investigated for decades, the initial steps of AR in vivo, however, remain largely unknown. A well elucidated model holds the view that AR occurs on the surface of the zona pellucida (ZP), which is triggered by binding of sperm with one of the ZP glycosylated protein, ZP3. However, this model fails to explain the large number of 'falsely' acrosome-reacted sperms found within the cumulus layer in many species examined. With the emerging evidence of cross-talk between sperm and cumulus cells, the potential significance of AR in the cumulus oophorus, the outer layer of the egg, has been gradually revealed. Here we review the acrosome status within the cumulus layer, the cross-talk between sperm and cumulus cells with the involvement of a novel sperm-released factor, NYD-SP8, and re-evaluate the importance and physiological significance of the AR in the cumulus in fertilization.

NYD-SP27, a novel intrinsic decapacitation factor in sperm / 亚洲男科学杂志(英文版)

Prior to fertilization sperm has to undergo an activation process known as capaciation, leading to the acrosome reaction. Till now, little is known about the mechanism for preventing premature capacitation in sperm although decapacitation factors from various sources have been thought to be involved. In this study, we report that NYD-SP27, an isoform of phospholipase C Zeta 1 (PLCZ1), is localized to the sperm acrosome in mouse and human spermatozoa by immunofluorescence using a specific antibody. Western blot and double staining analyses show NYD-SP27 becomes detached from sperm, as they undergo capacitation and acrosome reaction. The absence of HCO3-, a key factor in activating capacitation, from the capacitation-inducing medium prevents the loss of NYD-SP27 from sperm. The anti-NYD-SP27 antibody also prevents the loss of NYD-SP27 from sperm, reduced the number of capacitated sperm, inhibited the acrosome reaction induced by ATP and progesterone, and inhibited agonist-induced PLC-coupled Ca2+ mobilization in sperm, which can be mimicked by the PLC inhibitor, U73122. These data strongly suggest that NYD-SP27 is a physiological inhibitor of PLC that acts as an intrinsic decapacitation factor in sperm to prevent premature capacitation and acrosome reaction.

Effect of Huoxiang-zhengqi liquid on HCO(3)(-) secretion by intact porcine distal airway epithelium / 生理学报

The short-circuit current (I(SC)) technique was used to examine the effects of cAMP-evoking agents, forskolin/IBMX, and a Chinese medicinal formula, Huoxiang-zhengqi liquid (HZL) on HCO(3)(-) secretion by intact porcine distal airway epithelium. The freshly isolated airway epithelial tissue displayed a transepithelial basal current of (94.9±8.2) μA/cm(2), 16.6% and 62.7% of which was inhibited by amiloride (epithelial Na(+) channel blocker, 100 μmol/L) and NPPB (cystic fibrosis transmembrane conductance regulator Cl(-) channel blocker, 100 μmol/L). Substitution of Cl(-) with impermeable gluconate(-) in the K-H bath solution resulted in a basal current of (54.0±6.7) μA/cm(2), which could be abolished by further removal of HCO(3)(-) in the solution, indicating HCO(3)(-) secretion under unstimulated conditions. Application of forskolin/IBMX (10 μmol/L/100 μmol/L) stimulated an increase of (13.8±1.9) μA/cm(2) in I(SC) which could be blocked by Cl(-) channel inhibitor DPC. With Cl(-) and Cl(-)/HCO(3)(-) substitution, forskolin/IBMX evoked an increase of (7.3±0.5) μA/cm(2) in HCO(3)(-)-dependent, DPC-inhibitable I(SC) (I(HCO(3))). Noticeably, basolateral application of HZL (10 μL/mL) in normal K-H solution evoked an I(SC) of (15.9±2.4) μA/cm(2). The EC(50) of this I(SC) was (6.1±1.4) μL/mL. When substituting Cl(-), HZL stimulated an increase of (7.4±1.9) μA/cm(2) in I(HCO(3)), suggesting HZL-induced HCO(3)(-) secretion. After pretreating the epithelial tissues with forskolin/IBMX in Cl(-)-free K-H solution, HZL induced a further increase of (8.4±0.9) μA/cm(2) in I(HCO(3)), and pretreating tissues with HZL did not significantly affect the subsequent forskolin/IBMX-induced I(HCO(3)) response, indicating that HZL- and forskolin/IBMX-induced I(HCO(3)) responses appeared to be independent and be most likely mediated via different cellular mechanisms. Our results suggest that HCO(3)(-) can be secreted by porcine distal airway epithelium under unstimulated and stimulated conditions, and the stimulatory effect of HZL on HCO(3)(-) secretion in the distal airway epithelium shows HZL to be a hopeful new agonist for distal airway HCO(3)(-) secretion that could be of therapeutic significance.

Effects of Bak Foong Pill and its active components on body functions and gastrointestinal epithelial ion transport / 生理学报

Bak Foong Pill has been used traditionally for treating gynecological disorders for several centuries but also with a newly modified formula for treating postmenopausal symptoms. Cumulating evidence indicates that Bak Foong Pill acts on multi-systems and affects various organ functions. The present review discusses the effects of Bak Foong Pill and its active components on overall body function, with particular focus on the gastrointestinal epithelial ion transport and the related underlying mechanisms.

The role of extracellular ATP in the male reproductive tract / 生理学报

In addition to its well established role as a neurotransmitter, extracellular ATP has been considered as a paracrine/autocrine factor, either released from sperm or epithelial cells, in the male reproductive tract and shown to play a versatile role in modulating various reproductive functions. This review summarizes the signal pathways through which ATP induces anion secretion by the epithelia of the epididymis, as well as its epithelium-dependent modulation of smooth muscle contraction of the vas deferens. Finally, the overall role of ATP in coordinating various reproductive events in the male genital tract is discussed.

Epithelial ion channels in the regulation of female reproductive tract fluid microenvironment: implications in fertility and infertility / 生理学报

An optimal fluid microenvironment in the female reproductive tract is considered to be crucial for successful reproductive events. Fluid absorption and secretion across the reproductive tract epithelia largely depends on electrolyte transport through the apically and basolaterally located ion channels, working together with an array of other transporters. This review will discuss the role of epithelial sodium channel (ENaC) and the cystic fibrosis transmembrane conductance regulator (CFTR) in regulating the fluid volume and composition of the reproductive tract and their importance in various reproductive events such as sperm capacitation and implantation. Disturbance of the fluid microenvironment due to defects or abnormal regulation of these ion channels as causes for a number of pathological conditions, such as ovarian hyperstimulation syndromes, hydrosalpinx and infertility, is also discussed.

Bicarbonate secretion by the female reproductive tract and its impact on sperm fertilizing capacity / 生理学报

The luminal fluid environment of the female reproductive tract is considered critical for the sperm to undergo a series of molecular events leading to the final acquisition of their fertilizing capacity. It has been shown that the fluid in the female reproductive tract contains high content of HCO3- and it plays an important role in sperm functions including sperm motility, capacitation, hyperactivation and acrosome reaction. This review summarizes the effects of HCO3- on sperm functions occurring in the female reproductive tract and discusses the transport mechanisms involved in mediating uterine HCO3- secretion. New evidence is also presented to show possible cause of female infertility due to defective HCO3- transporting mechanism.

Basolateral membrane mechanisms involved in ligustrazine-stimulated anion secretion in rat distal colon / 生理学报

The present study investigated the cellular mechanism underlying the effect of ligustrazine on the ion transport in rat distal colon using the short-circuit current (I(SC)) technique. In freshly isolated colonic strips, basolateral addition of ligustrazine stimulated a rise in I(SC), which was resistant to basolateral application of neuronal sodium channel blocker tetrodotoxin (TTX), but inhibited by 55.2% by basolateral pretreatment with prostaglandin inhibitor indomethacin. The ligustrazine-induced I(SC) increase was inhibited by apical application of Cl(-) channel blockers diphenylamine-2,2'-dicarboxylic acid (DPC) and glibenclamide. Basolaterally administered bumetanide, an inhibitor of Na(+)-K(+)-2 Cl(-) cotransporter, inhibited ligustrazine-evoked current increases by 85.2% and basolateral exposure to Ba(2+), a non-specific potassium channels blocker, and blocked the current by more than 90%, indicating that basolateral Na(+)-K(+)-2 Cl(-) cotransporter and K(+) channels played an important role in the effect of ligustrazine. The results suggested that ligustrazine could stimulate rat distal colon (-) secretion that is mediated by basolateral Na(+)-K(+)-2 Cl(-) cotransporter and K(+) channel.

Regulation of Na+ absorption and Cl- secretion in the endometrium: switching mechanisms

No abstract available.