The Ratio of MI to DCI and Its Impact in the Treatment of Polycystic Ovary Syndrome: Experimental and Literature Evidences

Myo-inositol (MI) and d-chiro-inositol (DCI), two second messengers of insulin in various insulin-dependent processes, are implicated in polycystic ovary syndrome (PCOS). MI and DCI exert distinct functions in insulin signaling. While MI is involved in the activation of glucose transporters and glucose utilization, DCI is mainly involved in the glycogen synthesis. At ovarian level, MI plays a pivotal role in the FSH signaling while DCI promotes insulin-dependent androgen synthesis. Although MI and DCI fulfill different roles, often their biological activities are confused. A key point is the physiological plasma ratio of 40:1, between MI and DCI, in healthy subjects. It was shown in the PCOS treatment the efficacy of therapies based on the restoration of the appropriate MI:DCI ratio, in such a way as to prompt a new approach in the researches and clinical trials. Moreover, it has been demonstrated that MI is able to increase oocyte and sperm cell quality, opening new possibilities to assisted reproduction technology (ART). With the aim to clarify these two sets of issues and answer a number of research questions and also to develop future studies, the International Consensus Conference on myo- and d-chiro-inositol in obstetrics and gynecology was held in Florence in 2013. In this chapter are summarized the main conclusions on MI and DCI and the role of MI in ART.