Selenium and male reproduction

Selenium deficiency has long been documented to result in impaired male fertility in rats, mice and boars. The prominent feature of selenium-deficient spermatozoa is a distorted architecture of the mid piece, where normally the mitochondria are embedded into a keratinous matrix called the mitochondrial capsule. This material, which contains most of the selenium of sperm, is composed of oxidatively cross-linked proteins, a major component being the selenium phospholipid hydroperoxide glutathione peroxidase (PHGPx). PHGPx is abundantly synthesized in round spermatids under indirect control of testosterone. In late phase of spermatogenesis, the active soluble peroxidase is transformed into an enzimatically inactive structural protein by an oxidative process that is not understood in detail. Likely, it involves oligomerization of PHGPx itself, cross-linking of PHGPx with the sperm mitochondrion-associated cysteine-rich protein (SMCP) and other cysteine-rich proteins and selenadisulfide reshuffling with or without the aid of thioredoxin-glutathione reductase.