Adiponectin and reproduction.

Adiponectin is an adipocyte-derived cytokine that acts as a major regulator of insulin sensitivity. Adiponectin deficiency can result in severe diabetes and metabolic disorders in humans. Since its discovery, our understanding of adiponectin's biological functions has expanded from insulin sensitization properties to new effects on inflammation, immunology, and human reproduction. Indeed, both obesity and excessive leanness are associated with reproductive dysfunction. The objective of this chapter is to review such biological actions and the potential roles of adiponectin on human reproduction. There is accumulative evidence for direct effects of this adipokine on the late stages of folliculogenesis and on the development of a functional placenta. In addition, clinical and genomic studies associate hypoadiponectinemia with pregnancy-related disorders, including polycystic ovarian syndrome.