Pregnancy-associated homeostasis and dysregulation: lessons from genetically modified animal models

Physiological alterations occur in many organ systems during pregnancy. These changes are necessary for the adaptation to pregnancy-specific physiological processes in mother and fetus, and the placenta plays a critical role in the maintenance of homeostasis in pregnancy. Dysregulation of these functional feto-maternal interactions leads to severe complications. There have been many attempts to create animal models that mimic the hypertensive disorders of pregnancy, especially pre-eclampsia. In this review, we summarize the physiology of pregnancy and placental function, and discuss the placental gene expression in normal pregnancy. In addition, we assess a number of established animal models focusing on a specific pathogenic mechanism of pre-eclampsia, including genetically modified mouse models involving the renin−angiotensin system. Validation of these animal models would contribute significantly to understanding the basic principles of pregnancy-associated homeostasis and the pathogenesis of pre-eclampsia.