Insights into pH regulatory mechanisms in mediating spermatozoa functions

Abstract

Regulation of pH in spermatozoa is a complex and dynamic process as sperm cells encounter different pH gradients during their journey from testes to the site of fertilization in female genital tract. The precise regulations of pH in sperm cells regulate the sperm functions such as motility, hyperactivity, capacitation, and acrosome reaction. Electrophysiological, pharmacological, and molecular studies have revealed the presence of different ion channels and exchanger systems which regulate intracellular pH in sperm cells as well as regulate sperm functions. Recent studies also have shown the potential involvement of pH in the regulation of fertility competence of sperm cells, and alterations in pH have shown to impede sperm functions. This mini-review discusses the probable mechanisms involved in pH regulation in sperm cells and how pH is involved in regulation of various sperm functions.

Influence of the digestive/reproductive tract microbiota on chicken egg production beyond host genetics

“…Lactobacillusor other lactic acid bacteria-dominant communities were detected less abundant in the uterus and isthmus (~14.03%) and the relative abundance was lower than that of the mature human vaginal microbiota (~50%) [69]. Consistent with a recent study in chickens [66], this finding may be related to the alkaline pH value in the chicken reproductive tract that maintains sperm motility [70,71], in contrast to the low pH in humans that prevents pathogen infection and growth [72][73][74]. Exiguobacterium is a genus of bacilli and a member of the low-GC phylum Firmicutes; it has been found in areas covering a wide range of temperatures, pH values, salinity and other conditions [75], and it also produces organic acids and hydrolytic enzymes [76], even having some potential function in the degradation of toxic substances [77].…”

“…Six Bacteroidetes bacterial taxa were detected as isthmus-associated, Bacteroides species are thought to play a vital role in the breakdown of polysaccharides into simpler compounds that related to host immunity [88]. Acidic pH [68] and alkaline pH [70,71] values were observed in the chicken digestive and reproductive sites respectively. Thus, we speculate that the reproductive microbiota plays a vital role in improving protective immunity, defending against invasion of the reproductive tract by harmful bacterial and adaptation to pH levels.…”

Molecular Changes Induced by Oxidative Stress that Impair Human Sperm Motility

“…Indeed, the compromise of both of these parameters has been well documented in the context of cryopreservation [84][85][86][87] in which post-thaw sperm samples typically experience a burst of ROS and high levels of OS [85,86,88]. Sperm motility is also highly sensitive to pH and ion concentration (reviewed in [89]). The disruption of sperm membrane integrity alters the diffusion of ions across the membrane and dysregulates the function of ion pumps and channels, especially as those ion channels that are regulated by PUFAs (reviewed in [90]).…”

Capacitation-associated alkalization in human sperm is differentially controlled at the subcellular level

“…Additionally, pH i mediates the development of hyperactivated motility, a special kind of sperm movement characterized by asymmetrical flagellar beating, and which is necessary for successful fertilization (Mishra et al, 2018;Suarez, 2008). Such hyperactivation is mediated by the CATSPER1-CATSPER4 proteins and its auxiliary subunits (hereafter referred to generically as CATSPER), which are sperm-specific Ca 2+ channels that are activated by alkaline pH i through interaction with EFCAB9, a pHtuned Ca 2+ sensor that controls CATSPER gating (Hwang et al, 2019).…”