Myo-inositol in the treatment of male factor infertility

Abstract

About 187 million couples worldwide suffer from infertility, with the male factor being diagnosed in 2070% of cases. The main cause of idiopathic infertility has been recognized as the adverse effects of reactive oxygen species. On the one hand, the cellular antioxidant defense is a highly efficient multilevel system; therefore, the pharmacological targets may vary. On the other hand, antioxidant enzymes (superoxide dismutase, catalase, peroxidase) have high activity and specificity, which limits the pharmacological capabilities of direct antioxidants. Indirect methods, such as the normalization of mitochondrial function, are more promising. Mitochondria play a key role in providing energy for sperm motility (one of the main factors of male fertility). Myo-inositol (MI) derivatives involved in cell signaling regulate intracellular Ca2+ ion levels affecting mitochondrial oxidative metabolism and adenosine triphosphate production. Thus, mitochondrial antioxidants are of particular interest for therapeutic strategies. Currently, various routes and regimens of MI use in the treatment of males with oligo-astheno-teratozoospermia (OAT) are being considered in clinical practice. MI-based oral nutraceutical complexes for the treatment of male factor infertility contain both direct and indirect antioxidants. In vitro studies revealed damage to mitochondrial cristae in the sperm intermediate tract in patients with OAT. Experimental studies have demonstrated that mitochondrial structure is restored when sperm are incubated in an MI-containing medium. Clinical studies confirmed that sperm incubation in such an environment leads to increased sperm motility and viability in patients with OAT. Intravaginal administration of MI showed increased total sperm motility and an increased proportion of progressively motile sperm. It is the progressive motility that is considered the best marker for identifying quality and healthy sperm. This type of sperm is usually used for in vitro fertilization techniques. In addition, intravaginal MI administration improved the quality of cervical mucus and reduced its viscosity and crystallization. The effect of intravaginal MI on cervical mucus can be considered as an additional independent factor in increasing fertility.