Endocrine Factors and Their Effects on Placentation

Abstract

The endocrinology of human pregnancy involves endocrine and metabolic changes that result from physiological alterations at the boundary between mother and fetus. Known as the feto-placental unit, this interface is a major site of protein and hormone production and secretion. Many of the endocrine and metabolic changes that occur during pregnancy can be directly attributed to hormonal signals originating from this unit. Maternal adaptations to hormonal changes that occur during pregnancy directly affect the development of the fetus and placenta. Gestational adaptations that take place in pregnancy include establishment of a receptive endometrium, implantation and the maintenance of early pregnancy, modification of the maternal system in order to provide adequate nutritional support for the developing fetus, and preparation for parturition and subsequent lactation. As described already, a successful human pregnancy requires cytotrophoblasts from the fetal portion of the placenta to adopt tumor-like properties. So, migration and invasion of cytotrophoblasts into the maternal endometrium are key events in human placentation. Trophoblast infiltration of maternal decidua and spiral arteries is regulated by a fine balance between the production of multiple metalloproteinases (MMP) such as MMP1–MMP16 (gelatinases, collagenases, and stromelysins), their physiological activators, and their inhibitors (TIMP1 and TIMP2) (Cohen and Bischof 2007). Many factors have been shown to regulate invasive capacities of EVTs. Some cytokines, such as adiponectin, interleukin (IL) IL-6, IL-10, and IL-11, leukemia inhibitory factor, CCNs, epidermal growth factor, angiotensin II, and leptin, have recently been described to modulate synthesis and release of one or more of these MMPs and TIMPs (Castellucci et al. 2000; Gonzalez et al. 2001; Qiu et al. 2004). In this chapter we will describe the key endocrine/cytokine factors involved in early placentation.