Leptin action in normal and pathological pregnancies

Abstract

Leptin is now considered an important signalling molecule of the reproductive system, as it regulates the production of gonadotrophins, the blastocyst formation and implantation, the normal placentation, as well as the foeto-placental communication. Leptin is a peptide hormone secreted mainly by adipose tissue, and the placenta is the second leptin-producing tissue in humans. Placental leptin is an important cytokine which regulates placental functions in an autocrine or paracrine manner. Leptin seems to play a crucial role during the first stages of pregnancy as it modulates critical processes such as proliferation, protein synthesis, invasion and apoptosis in placental cells. Furthermore, deregulation of leptin levels has been correlated with the pathogenesis of various disorders associated with reproduction and gestation, including polycystic ovary syndrome, recurrent miscarriage, gestational diabetes mellitus, pre-eclampsia and intrauterine growth restriction. Due to the relevant incidence of the mentioned diseases and the importance of leptin, we decided to review the latest information available about leptin action in normal and pathological pregnancies to support the idea of leptin as an important factor and/or predictor of diverse disorders associated with reproduction and pregnancy.

Keywords: gestational diabetes; growth restriction; leptin; placenta; polycystic ovary syndrome; pre-eclampsia; recurrent miscarriage; reproduction.

Figure 1

Leptin action during the first stages of pregnancy. Leptin seems to play a crucial role during the first stages of pregnancy as it modulates critical processes such as implantation and placentation, as well as foetus development. The figure summarizes the most important actions of leptin during early gestation (green), highlighting its role in the maternal–foetal interface. It is also shown the different type of cell which expresses leptin receptor (LEPR) and produce leptin (violet). CT: cytotrophoblast, ST: syncytiotrophoblasts.

Figure 2

Leptin association pregnancy disorders. Deregulation of leptin levels has been correlated with the pathogenesis of various disorders associated with reproduction and gestation, including polycystic ovary syndrome (PCOS), recurrent miscarriage (RM), gestational diabetes mellitus (GDM), pre‐eclampsia (PE) and intrauterine growth restriction (IUGR). The figure summarizes the link between leptin and the mentioned diseases, including suggested causes and consequences of these pathologies.