Regulation of sperm function by reactive oxygen species

Abstract

Sperm capacitation can be increased by the addition of reactive oxygen species (ROS) and decreased by antioxidants. Broadly consistent results have been achieved with a wide variety of methods and across different species. Exposure to ROS increases protein tyrosine phosphorylation consequent on an increase in cAMP and activation of tyrosine kinase and inhibition of tyrosine phosphatase. The measurement of ROS production by sperm is complicated by contamination of suspensions by leukocytes, laying many studies open to doubt. In human sperm the observation that extracellular NADPH could support superoxide production detected with the chemiluminescent probe lucigenin and had physiological effects similar to hydrogen peroxide led to the suggestion that they contained NADPH oxidase activity to generate ROS to support capacitation. However, the realization that lucigenin can signal superoxide artefactually, combined with failure to detect superoxide production using spin trapping techniques or to detect NADPH oxidase components in mature sperm, and confirmation of old reports that NADPH solution contains substantial amounts of hydrogen peroxide due to autoxidation, have undermined this hypothesis. Although the presence of significant NADPH oxidase activity in mature human sperm now seems less likely, other observations continue to suggest that they can make ROS in some way. There is stronger evidence that animal sperm can make ROS although these may be mainly of mitochondrial origin.

Cryopreservation of a small number of human sperm using enzymatically fabricated, hollow hyaluronan microcapsules handled by conventional ICSI procedures

“…In addition, when ICSI is Capsule Hollow HA microcapsules can be used for the cryopreservation of a small number of sperm without producing adverse effects on sperm quality. performed using a small number of sperm, it takes a much longer time until sperm injection, causing the accumulation of reactive oxygen species [3,4]. Such changes in culture conditions have been shown to be involved in the lipid peroxidation of cell membranes, nuclear DNA fragmentation, and delay of embryo development [5][6][7][8].…”

Spermatozoa Epididymal Maturation in the Mexican Big-Eared Bat (Corynorhinus Mexicanus)

“…Many important tasks related to these processes appear to be under redox control [Leclerc et al 1997;de Lamirande et al 1997;Lewis and Aitken 2001;Ford 2004]. We have recently shown [Arenas-Ríos et al 2007] that, in C. mexicanus, redox equilibrium of the micro-environments associated with the milieus by which mammalian spermatozoa must progress during its transit through the epididymis seems to be specifically and differentially controlled with the compartmentalization of epididymal functions.…”

Physiological and Pathological Roles of Free Radicals in Male Reproduction

“…During transit and storage in the epididymis, spermatozoa undergo membrane, nuclear and enzymatic remodeling, involving the release, attachment and rearrangement of surface proteins [6,30,51]. Such changes are based on the assembly of several signal transduction pathways necessary for the subsequent ability of spermatozoa to undergo hyperactivation and capacitation.…”

“…Mitochondria require such protection as their proper function is crucial for metabolism, cell cycle control and oxidative balance [51,53,54].…”

“…More importantly, a direct relationship has been reported between male fertility and phospholipid hydroperoxide glutathione peroxidase (PHGPx; GPx4), a selenoprotein that is highly expressed in testicular tissue and has a prominent role in the formation of the mitochondrial capsule [51,53,54]. Glutathione peroxidases remove peroxyl (ROO • ) radicals from various peroxides, including hydrogen peroxide [13].…”