From Myo-inositol to D-chiro-inositol molecular pathways.

OBJECTIVE: Inositol is a carbocyclic sugar polyalcohol. By epimerization of its hydroxyl groups, nine possible stereoisomers can be generated, two of major physiological and clinical relevance: myo-inositol and D-chiro-inositol. Myo-inositol and D-chiro-inositol are normally stored in kidney, brain and liver and are necessary for functions, such as signal transduction, metabolic flux, insulin signaling, regulation of ion-channel permeability, stress response and embryo development. In this narrative review, we summarize the mechanisms by which myo-inositol and D-chiro-inositol can be synthesized and absorbed and their possible role in the etiopathogenesis of neural tube defects. MATERIALS AND METHODS: We performed an online search in the PubMed database using the following keywords: "inositol", "D-chiro-inositol", "myo-inositol", "neural tube defects and inositol". RESULTS: Inositol requirements are partly met by dietary intake, while the rest is synthesized endogenously. Inositol deficiency may be involved in the pathogenesis of diseases, such as metabolic syndrome, spina bifida (a neural tube defect), polycystic ovary syndrome and diabetes. Supplementation of the two inositol stereoisomers, D-chiro-inositol and myo-inositol is important to prevent these conditions. CONCLUSIONS: Inositol is fundamental for signal transduction in the brain, kidneys, reproductive organs and other tissues in response to neurotransmitters, hormones and growth factors. Various genes are involved in inositol metabolism and associated pathways. Altered inositol concentrations are observed in several diseases. Analysis of the genes involved in inositol metabolism may provide important information for the clinical management of these conditions.

Effect of metabolic and antioxidant supplementation on sperm parameters in oligo-astheno-teratozoospermia, with and without varicocele: A double-blind placebo-controlled study.

Since sperm require high energy levels to perform their specialised function, it is vital that essential nutrients are available for spermatozoa when they develop, capacitate and acquire motility. However, they are vulnerable to a lack of energy and excess amounts of reactive oxygen species, which can impair sperm function, lead to immotility, acrosomal reaction impairment, DNA fragmentation and cell death. This monocentric, randomised, double-blind, placebo-controlled trial investigated the effect of 6 months of supplementation with l-carnitine, acetyl-l-carnitine and other micronutrients on sperm quality in 104 subjects with oligo- and/or astheno- and/or teratozoospermia with or without varicocele. In 94 patients who completed the study, sperm concentration was significantly increased in supplemented patients compared to the placebo (p = .0186). Total sperm count also increased significantly (p = .0117) in the supplemented group as compared to the placebo group. Both, progressive and total motility were higher in supplemented patients (p = .0088 and p = .0120, respectively). Although pregnancy rate was not an endpoint of the study, of the 12 pregnancies that occurred during the follow-up, 10 were reported in the supplementation group. In general, all these changes were more evident in varicocele patients. In conclusion, supplementation with metabolic and antioxidant compounds could be efficacious when included in strategies to improve fertility.